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UPDATE ON ANESTHESIA MANAGEMENT FOR INFANTS AND CHILDREN Edmond C. Bloch, MB, ChB, FFARCS
During the past decade, pediatric anesthesia has matured into an important subspecialty of anesthesia. Major texts have appeared, and the literature has grown remarkably. Journals and societies devoted to the specialty have been established, and training to high standards is available in leading institutions in Europe and North America. The fully trained pediatric anesthesiologist is board certified in anesthesiology and has had a year or more of fellowship training in pediatric anesthesia. Many such physicians are also board certified in pediatrics and intensive care. THE OUTCOME
Despite this development, Motoyama, in an interesting review, 37 points out that the mortality rate relating to anesthesia in children is three to four times greater than in the general population. This ratio has not changed in 30 years. The dominant causes continue to be hypoxia related to airway or pulmonary complications and inappropriate management of fluids and blood volume. These are not the inevitable consequences of anesthesia, are eminently preventable, and are largely the result of human error. Unfortunately, all human beings, irrespective of ability and experience, make errors. 3 It is also obvious to any interested observer that many trained anesthesiologists who are otherwise very proficient are uncomfortable and indeed incompetent when it comes to dealing with children. It seems that the reasons for this are inadequate training and experience. This was emphasized in a review of perioperative deaths among children, which is subtitled "Standards of care are high, but those who don't care for children regularly shouldn't care for them at all."25 From the Division of Pediatric Anesthesiology, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
SURGICAL CLINICS OF NORTH AMERICA VOLUME 72 • NUMBER 6 • DECEMBER 1992
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PREOPERATIVE CONSIDERATIONS What Investigations?
What preoperative investigations are needed for anesthesia? This question often arises in the surgical clinic. A succinct history and physical examination are routine. Beyond that, in the absence of specific indications, routine laboratory tests have been found to contribute little to patient care and could reasonably be eliminated. 21 , 26 Certainly, routine urinalysis is in this category. 40 Nevertheless, most anesthesiologists would, as a minimum, probably require a hematocrit value in otherwise healthy children. Roy et al" reviewed the value of routine preoperative testing in pediatric patients and concluded that healthy patients aged 5 years and older Who are scheduled for minor surgery do not require routine hemoglobin determinations. They also questioned the value of such determinations in children aged 1 to 5 years. Communication between surgeon and anesthesiologist would, as always, be advisable to avert lastminute problems. Cough and Rhinorrhea
The child with a history of a recent fever, cough, and rhinorrhea raises doubts about the wisdom of embarking on anesthesia for elective surgery. Is this picture the precursor of a serious illness (e.g., measles, meningitis), a viral infection, or simply an allergy? The immediate concerns of the anesthesiologist are threefold. First, an irritable upper respiratory tract predisposes to cough and to laryngospasm with hypoxia during both induction and emergence. Second, the likelihood of postoperative complications (retention of secretions, atelectasis, pneumonia) is significantly increased. Finally, a generalized viral syndrome may affect the myocardium, occasionally resulting in a fatal dysrhythmia. A helpful guide to assessment is provided by the parent's response to the question: "Has your child been sick?" Symptoms such as lethargy, loss of appetite, somnolence, sweating, and abnormal behavior would, in the author's opinion, support postponement of the operation, as would an elevated body temperature and an abnormal white cell evaluation. On the other hand, some 15% to 20% of the population suffers from some type of respiratory allergy.l7 This and other conditions such as chronic sinusitis causing a nasal discharge are not contraindications to elective surgery. The surgical procedure must be considered. As an example, a poor candidate would be one for thoracic or abdominal surgery because of the reluctance or inability to cough effectively postoperatively, whereas this would not apply to a minor procedure on a limb. The postponement of surgery creates a hardship for the family. They may have traveled a long way to the hospital, and the parents may have taken time off from work and may not be able to do so soon again. They also may not be able to again afford the time and expense of travel and overnight lodgings. All these factors are of concern to the anesthesiologist, although the patient's welfare remains the primary consideration. If the decision is made to postpone the procedure, it would be wise to reschedule it for no sooner than 2 full weeks after the disappearance of symptoms. In fact, one study suggests that it is during this period that complications can be most troublesome. 52 A thoughtful and comprehensive review by Berry is recommended for further reading. 6
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NPO Status
Prolonged starvation and dehydration (NPO) should no longer be condoned in the management of the child awaiting surgery and anesthesia. A recent study 48 has indicated that clear fluids given up to 2 hours before induction of anesthesia do not increase the risk of pulmonary aspiration in children. As pointed out by the accompanying review,14 this has the additional benefit of avoiding the induction of anesthesia in a hypovolemic and hypoglycemic patient. Other studies 34, 46, 48, 50, 57 found no difference in gastric pH or residual volume between those patients who fasted for 8 or more hours versus those who fasted for 2 or 3 hours. This finding has led several pediatric anesthesia services, including our own, to alter their NPO requirements. These studies and their outcome do not apply to the patient with a disease process that predisposes to a "full stomach" and vomiting (e.g., trauma, shock, ileus, peritonitis, bowel obstruction) or to gastroesophageal reflux. In these patients, preoperative intravenous hydration, a 4- to 6-hour NPO period, and pretreatment with ranitidine 2.0 mglkg and 0.3 M sodium citrate (Bicitra) 0.5 mllkg orally is advisable. Premedication
The child's aversion to "needle sticks" has resulted in various premedication strategies ranging from none at all through pharmacologic methods to parental support only. Preoperative atropine, considered an essential when ether was in vogue, is now used selectively by some and often routinely omitted by others. Sedation and anxiolysis can be achieved by the nasal, oral, and rectal routes. Innovations include fentanyl lollipops and midazolam candy; these drugs can also be administered nasally and, in the case of midazolam, rectally. The Parent at Induction
For some years, it has been our practice to allow a parent to be present during induction of anesthesia in children over 6 months of age. Pediatric psychologists agreed that this age restriction was reasonable, as young infants easily take to an appropriate stranger and seem unaffected by separation from the parent. We have no upper age limit to this practice but have found that most older adolescents are happy to proceed without a parent present. In our experience, the child benefits enormously from the comfort, reassurance, and emotional support provided by the parent (Fig. 1). As a consequence, we have been able to abolish pharmacologic premedication with all its uncertainties and timing difficulties. The occasional parent declines the privilege, but most are appreciative of it, and we have had no inappropriate behavior on the part of the parent or other untoward incidents. Mediastinal Masses
A child with a mediastinal mass may present for cervical lymph node biopsy to establish a diagnosis or for excision of the mass. Case reports in the anesthetic literature 35 describe the problems encountered, and some document
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Figure 1. The child readily accepts the mask while being comforted by the mother.
intraoperative deaths. 39 One component of the problem is compression of the intrathoracic airways by the bulk of the mass any time during anesthesia or during emergence. This pressure is associated with loss of respiratory muscle tone, particularly after the use of muscle relaxants. Airway obstruction may be partial or complete. The other component of the problem is right ventricular outflow obstruction or pulmonary artery compression. Spontaneous ventilation should be preserved whenever possible. In the event of difficulties, a change in patient position or intubation with a rigid bronchoscope should be considered. Timely preoperative consultation with the anesthesiologist is mandatory to establish risk factors and to decide on the best course of action. A history of dyspnea on exertion or related to posture is very significant. Examination of the lung fields may reveal abnormal breath sounds. The intrathoracic airway must be evaluated by pulmonary function tests including flow-volume loops in the supine and upright positions, which are the most sensitive indicators of airway obstruction. Chest radiography (anteroposterior and lateral views) and a CT scan are also needed. If the anesthesiologist considers the hazards of general anesthesia to be prohibitive, an alternate treatment strategy will be required. This may be either biopsy using local anesthesia or radiation therapy or chemotherapy to reduce tumor bulk. If these are not possible or acceptable, consideration will have to be given to general anesthesia with rigid bronchoscopy and cardiopulmonary bypass standby.
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MONITORING Pulse Oximetry
In the past, the anesthesiologist relied on cyanosis or bradycardia to be alerted to hypoxemia. Much earlier warning is now provided by the pulse oximeter, which has been shown in many studies to provide a high degree of accuracy. Additionally, changes in the amplitude of the bar graph or in the waveform provide evidence of vasoconstriction or vasodilation. This is useful in the evaluation of intravascular volume status." In addition, vasodilatation resulting from sympathetic blockade is useful evidence of the onset of supplementary regional analgesia in an anesthetized child 60 following procedures such as spinal and epidural analgesia or stellate ganglion and axillary plexus blocks. Pulse oximetry is probably the most significant technologic advance in pediatric anesthesia and intensive care in the last decade. Failure to use pulse oximetry in the operating room, in the postanesthesia care unit, in the intensive care area, and during the transport of sick pediatric patients would be very difficult to justify. The American Society of Anesthesiologists, in publishing Standards for Basic Intra-operative Monitoring,53 effective on January 1, 1991, states that "a quantitative method of assessing oxygenation such as pulse oximetry shall be employed." The same body also "encourages" the use of capnography to confirm correct placement of the endotracheal tube and for monitoring of the adequacy of ventilation. This facility now is often combined with the monitoring of the concentration of anesthetic gases and vapors by infrared analysis or mass spectrography. Intraoperative transesophageal echocardiography to monitor cardiac function is currently of very limited use in pediatric patients. Small probes are being developed, but at present, the smallest ones are too large to be used in children weighing less than 25 to 30 kg (Fiona Clements, MD, personal communication, December 1991). In cardiac surgery, epicardial echo and Doppler color flow imaging have been found useful. 56 Automated Data Acquisition
Record keeping is an essential part of anesthesia monitoring. In some respects, manually generated records are self-defeating in that they distract the anesthesiologist from patient observation while data are being entered. Many such records are illegible, untidy, crowded with acronyms and abbreviations, and indecipherable to the point of being useless. Automated computer-generated record-keeping systems have developed to the extent that they are considered cost effective and efficient. They are being installed in major institutions as part of the hospital's data retrieval and storage system and are legally acceptable. INDUCTION OF ANESTHESIA Anesthetic Agents
Propofol (Diprivan) is a new intravenous induction agent. Its main attraction is that recovery is more rapid and complete than after pentothal, and it is therefore useful for short procedures and for ambulatory anesthesia. New
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muscle relaxants (alcuronium and vecuronium) have properties that make it possible to avoid the undesirable effects of the older products. The relaxant of choice for patients with renal or hepatic insufficiency is alcuronium, because its degradation is by other metabolic pathways. Vecuronium is useful in highrisk patients or in patients with a history of allergies because it does not stimulate histamine release and has no effect on hemodynamic parameters. Two recently introduced non-depolarizing muscle relaxants, doxacurium23 and mivacurium,22 have not yet gained widespread acceptance. The search for an ultra-short-acting non-depolarizing muscle relaxant to replace succinylcholine has made progress in that the newer ones mentioned above have a shorter duration of action than pancuronium or curare. Masseter Spasm and Malignant Hyperthermia
Masseter spasm following the administration of succinylcholine for tracheal intubation presents as resistance to passive opening of the mouth prior to laryngoscopy. It may be the result of too small a dose of the relaxant,35 but its association with malignant hyperthermia remains suspect and is widely debated. 3O Some anesthesiologists may elect to postpone the procedure pending investigation of the patient for malignant hyperthermia. Others mayor may not administer dantrolene before proceeding with the anesthetic with a heightened awareness and with meticulous monitoring. Malignant hyperthermia remains one of the pediatric anesthesiologist's most serious concerns. Enthusiastic research in both Europe and the United States aims at elucidating the etiology and also finding a noninvasive diagnostic test to replace the halothane-caffeine contracture test, which is available at relatively few centers and requires the patient's presence for a muscle biopsy. Expert advice for dealing with a case is available through a hotline maintained by The Malignant Hyperthermia Association (MHAUS; phone number 209-6344917).
ENDOTRACHEAL INTUBATION Awake Intubation
Awake intubation in the neonatal infant is performed as a routine by some anesthesiologists. Others will reserve it for the neonate who is at risk of regurgitation and aspiration, or when they are confronted with an airway known to be or seemingly difficult. The technique has fallen into disrepute with the realization that it is accompanied by hypertension and an increase in intracranial pressure,20 which may result in intraventricular hemorrhage in the newborn. Newer Aids to Intubation
Newer methods have been described for dealing with the difficult pediatric airway.19 Most are the result of advances in technology, which have produced the pediatric version of the Bullard laryngoscope 7 (Fig. 2, Circon Corporation, Stamford, Connecticut), the light wand1 (Fig. 3, Aaron Medical Industries, St. Petersburg, Florida), and flexible fiberoptic bronchoscopes of 2.2-mm external
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Figure 2. The Bullard laryngoscope. 7
diameter suitable for use with a 3.0-mm inner-diameter endotracheal tube (Olympus Corporation, Lake Success, New York). The light wand is a flexible lighted stylet that is inserted down an endotracheal tube (a 5.5 mm inner diameter is the smallest that can be used with it). In a darkened room, the assembly is passed down the anesthetized pharynx and, guided by transillumination of the tissues of the neck, advanced through the glottis, whereupon
Figure 3. The light wand.'
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the endotracheal tube is advanced over the wand into the trachea, and the wand is withdrawn. The laryngeal mask airway (Fig. 4, Colgate Medical, Reading Barks, England) has become popular since Brain described it in 1983. 8 It was approved for use in the United States in late 1991. It resembles a small anesthetic face mask, to which is attached a short length of tubing. It is introduced much like an oral airway and positioned in the hypopharynx just above the larynx. There is no need to visualize the glottis or to insert an endotracheal tube, and, in one of its four sizes, the mask can be used with both spontaneous and controlled ventilation for all patients more than a few weeks of age. 36 THERMAL REGULATION
Metabolic heat production is not depressed by anesthesia unless the patient is paralyzed, when it is reduced by approximately 25%. However, thermal regulation is affected by anesthesia and the circumstances surrounding it, such as exposure of the patient to cold operating rooms and surfaces and during transportation to and from the operating suite. All are not agreed on the efficacy of the various measures used to preserve thermal balance. Heated humidified inspired gas mixtures do not contribute much, but they are of significant benefit in preserving ciliary and bronchomotor function and in liquefying secretions. The blanket circulating warm water under the patient has been shown not to be useful in patients weighing more than 10 kg;24 in fact, it would seem better to place the blanket over the patient when possible. Overhead heating by infrared lights is not as effective as simply covering the patient with a sheet or blanket, which will reduce the heat lost by convection and radiation to surrounding cold surfaces. To be avoided is the unnecessary exposure of the patient during transport and during induction of anesthesia and surgical preparation, as well as of the viscera during surgery.
Figure 4. The laryngeal mask airway.8
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It is generally agreed that the lower quarter of the esophagus is the best site for obtaining temperature measurements. If it is iriaccessible, the nasopharynx may be used. Rectal temperature probes are best avoided; perforation of the rectum by a temperature probe has been reported in the neonate, and we have seen one such case with a fatal outcome in our hospital. REGIONAL ANESTHESIA
Bier, in 1889, was the first to publish a study of the use of regional anesthesia in children. His techniques gained enthusiastic acceptance for several years but progressively fell into disuse, and by the end of the Second World War, regional anesthesia in children had been almost completely abandoned. IS The conscious child was, and still is, a poor candidate for regional anesthesia because most children have a healthy fear of needles, and it is extremely difficult if not impossible to place the needle accurately in a frightened child in whom the margin for error is small. However, the modern pediatric anesthesiologist has safer and more effective means of dealing with this situation, and the past few years have seen a reintroduction and expansion of the use of regional anesthesia in children. For Surgical Procedures
When used as a component of general anesthesia, epidural or spinal anesthesia reduces or may even abolish the stress response to surgery and permits a reduction in the amount of anesthetic agent used; this shortens recovery time. If used in this way for abdominal procedures, regional anesthesia provides a measure of muscle relaxation and will also, by autonomic blockade, markedly reduce bowel distention during surgery. It reduces the incidence of postoperative nausea and vomiting, and it provides a very effective way of managing immediate postoperative pain without the side effects of narcotics (respiratory depression, urinary retention, nausea and vomiting, pruritus). There is the additional benefit of facilitating postoperative physical therapy and other procedures applied for the reduction of postoperative complications. The disadvantages of regional anesthesia include the extra time needed to perform the procedure and to allow it to become effective, the technical skill and dexterity required, and the fear of complications and legal ramifications. Absolute contraindications are the absence of consent by the parent or patient, progressive neurologic disease, coagulopathy, local infection, and anatomic aberrations. The maximum doses for infiltration when performing peripheral nerve blocks or field blocks are lidocaine 4 to 6 mg/kg and bupivacaine 2.5 to 3.0 mg/kg. The higher doses are for use only with epinephrine 1:200,000,62 which must not be used for the penis or the digits. Spinal Anesthesia
Subarachnoid block ("spinal anesthesia") is used mostly for inguinal hernia repair in the formerly premature infant with bronchopulmonary dysplasia. In patients with bronchopulmonary dysplasia, this technique is attractive in that general anesthesia and endotracheal intubation are avoided. Interestingly, these infants are not prone to the hypotension seen in older children and adults
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following subarachnoid block, but they are, like other children in their clinical category, at risk to develop postoperative apneic spells. A recent report"' describes disturbing complications in that, of 45 patients, 20 required supplementary general anesthesia, 6 required assisted ventilation perioperatively, and 5 had apneic spells postoperatively. Epidural Anesthesia
Caudal epidural anesthesia is often used to supplement general anesthesia and to provide postoperative anesthesia below the umbilicus. Above this level, lumbar or thoracic epidural anesthesia is preferred. Specially designed pediatric kits are available for these techniques. Some complications of regional anesthesia that may concern the surgeon include vomiting and urinary retention. Busoni and Andreuccetti,'3 in their series of 763 caudal epidural anesthesia cases, found no urinary retention and vomiting in only 5% of patients, whereas two other groups59, 64 report a 30% incidence of vomiting in series totalling 88 caudal epidural anesthetics. Vomiting13 and urinary retention58 occur more frequently when morphine is added to the local anesthetic mixture.62 Therapeutic Applications
The sympathetic blockade resulting ftom regional anesthesia has been used to treat upper 2• and lower limb ischemia in patients with meningococcal septicemia,>' 55 chronic vascular disease/7 vasospasm following trauma33 or vascular cannulation in the intensive care unit 45 or radiology department, and accidental intra-arterial injection. 5 Stellate ganglion blockade may control lifethreatening tachydysrhythmia. 42 POSTOPERATIVE CONSIDERATIONS Nausea and Vomiting
Postoperative nausea or vomiting may be anticipated in about 10% of patients. It is more likely in the patient who has experienced it after a previous anesthetic and following certain procedures (abdominal or strabismus surgery). It is seen more frequently between the ages of 3 and 5 years. Current prophylaxis is by the intravenous administration of droperidol 0.02 mg/kg on induction" and intravenous metoclopramide 0.15 mg/kg on arrival in the recovery area. 10 Postoperative Apnea
Life-threatening postoperative apnea has been identified in young, formerly premature infants after they have received general anesthesia,3l, 52 and it is more likely to occur in those with a history of apneic spells. Infants are considered to have been born prematurely when they have been born at less than 37 weeks of gestation, as determined by a Dubowitz evaluation' • at birth. The postconceptional age at which postanesthesia apnea ceases to be a concern ranges from 44 to 60 weeks, with no clear agreement. In our institution, preterm
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infants who are younger than 60 weeks' postconceptional age28 when subjected to general or regional anesthesia must be monitored continuously for at least 12 hours postoperatively. If the infant has a postoperative apneic event during that time, monitoring must be continued until at least 12 apnea-free hours have elapsed. These patients, sometimes admitted as day cases, must remain in the hospital overnight or longer if necessary. In the term infant, postoperative apnea is not common, but if there is a history of apnea, these infants should be dealt with in the same way as the ex-preemie. PAIN MANAGEMENT Divine is the work to overcome pain. HIPPOCRATES (460-370 BC)
A thorough review by Lloyd-Thomas32 is recommended to those interested in the problem of postoperative pain. We are reminded of the unfounded belief that the magnitude of the response to pain in children, especially in infants and neonates, is not as great as in adults. The justification for this erroneous assumption is the fear of administering suitable analgesics in adequate doses, of errors in dosage, of cardiovascular or respiratory depression, and of depressed levels of consciousness. Evidence that pain is underrated and undertreated in children is therefore not surprising. There has been an increasing amount of scientific evidence that neonates respond to pain. Arnand and Hickey, in an excellent review,' cite neuroanatomic, neurochemical, hormonal, metabolic, physiological, and behavioral evidence to support this. New Techniques
New routes for the administration of drugs have been described, together with their efficacy and complications. These techniques include the transmucosal, nasal, buccal, and trans dermal routes for the administration of fentanyl, sufentanil, and midazolam. The neuraxis provides two routes for pain management. Epidural bupivacaine will prOvide 4 to 6 hours of analgesia; this can be extended for as long as 20 hours by the addition of morphine, although possibly at the cost of a higher incidence of vomiting. 59, 64 Intrathecal morphine provides prolonged analgesia after procedures as diverse as exploratory laparotomy, craniofacial reconstruction,54 and spinal fusion. '6 Respiratory depression following epidural or intrathecal opiates in children is unpredictable, and its incidence varies. Valley and Bailey58 reviewed 136 patients who had received epidural caudal morphine and found that respiratory depression increases with higher doses (0.075-0.100 mglkg) and is more frequent under 1 year of age. They found the incidence of side effects (dose 0.070 mg/kg) to be urinary retention 51%, of whom 70% needed catheterization; vomiting 7.7%; and pruritus 3.1%. Respiratory monitoring in an intensive care setting for as long as 24 hours is strongly advised for every pediatriC patient who receives opiates via the epidural or intrathecal routes. Patient-controlled Analgesia
A good description of patient-controlled analgesia is provided by Scherpereel.·7 This is a drug delivery system for the control of acute pain using
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negative feedback technology in a closed loop system in which the patient plays an active role. It overcomes the problems of the traditional analgesic protocol, which is not suited to all patients because of individual differences in drug pharmacokinetics and pharmacodynamics. It also eliminates the underprescribing of opiates by physicians in pediatric patients for fear of dangerous side effects. Safe and effective delivery of these drugs on patient demand can be achieved by using various intravenous delivery systems, modes, and dosing parameters. The device is programmed by the physician to provide on-demand dosing (where a constant predetermined dose is self administered) or a constant minimum-rate ("background") infusion plus on-demand dosing. The physician also sets the incremental dose per demand, the lockout interval, and the maximum dose per unit of time. There is no doubt that patient-controlled analgesia provides better pain management. The patient or parent is given decisional control, relief is almost immediate and independent of nurse availability, and opiate requirements are decreased. Patients often choose less than the available total dose of analgesic, thereby balancing pain relief against side effects. Morphine sulfate and meperidine (Demerol) have been approved for patient-controlled use, but other drugs have been used. In most children over 5 years of age, patient-controlled analgesia can replace intramuscular injections. Mowbray and Gaukroger38 describe its satisfactory use in three older children for as long as 41 days, during which time no patient developed tolerance or clinical signs of dependence. The principles of demand analgesia are now being investigated using other agents such as local anaesthetics and via other routes, mainly the epidural space. Patientcontrolled analgesia and epidural opioids are fast becoming the methods of choice for the management of postoperative and long-term pain in children in many hospitals. A New Analgesic
The narcotics remain the primary analgesics, but because of their wellknown undesirable effects, the search for alternative agents continues. Ketorolac tromethamine (Toradol), at present not approved for use in children, is an inhibitor of prostaglandin synthesis and a powerful non-opioid analgesic. It is available in a syringe ready for intramuscular injection. Studies in adults have shown intramuscular ketorolac to be as effective as63 or even superior to41 intramuscular morphine after major surgery. When administered by continuous intramuscular infusion, it reduced patient-controlled morphine use by 49% .'2 There were no serious side effects, and ventilatory depression was insignificant when compared with that caused by morphine! SUMMARY
This review aims at providing the pediatric surgeon with an update on the most important issues in pediatric anesthesia and the changes that have taken place over the last few years. Many practices, entrenched in tradition, are being modified in the light of research that has provided new knowledge, drugs, and techniques. Pediatric anesthesia requires dedication, a sense of anticipation, meticulous attention to detail, and an individual who derives enormous satisfaction from the pleasure to be had from dealing with these small patients and their families.
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References 1. Ainsworth QP, Howells TH: Transilluminated tracheal intubation. Br J Anaesth 62:494-497, 1989 2. Anderson CTM, Berde CB, Sethna NF, et al: Meningococcal purpura fulminans: Treatment of vascular insufficiency in a 2-year-old child with lumbar epidural sympathetic blockade. Anesthesiology 71:463-464, 1989 3. AlInut MF: Human factors in accidents. Br J Anaesth 59:856, 1987 4. Arnand KJS, Hickey PR: Pain and its effects in the human neonate and fetus. N Engl J Med 317:1321-1329, 1987 5. Berger JL, Nimier M, Desmonts JM: Continuous axillary plexus block in the treatment of accidental intraarterial injection of cocaine [letter]. N Eng! J Med 318:930, 1988 6. Berry FA: The child with the runny nose. In Anesthetic Management of Difficult and Routine Pediatric Patients. New York, Churchill Livingstone, 1986, pp 349-367 7. Borland LM, Casselbrant M: The Bullard laryngoscope: A new oral laryngoscope (pediatric version). Anesth Analg 70:105-108, 1990 8. Brain AIJ: The laryngeal mask. Br J Anaesth 55:801-804, 1983 9. Bravo LJC, Mattie H, Spierdyk J: The effects on ventilation of ketorolac in comparison with morphine. Eur J Clin Pharmacol 35:491-494, 1988 10. Broadman LM, Cerruzi W: Metodopramide reduces the incidence of vomiting following strabismus surgery. Anesthesiology 72:245-248, 1990 11. Brown RE, James JT, Weaver RG, et al: Low dose droperidol vs standard dose droperidol for prevention of vomiting after strabismus surgery. Anesth Analg 70:S37, 1990 12. Bums JW, Aitken HA, Bullingham CS, et aI: Double-blind comparison of the morphine sparing effect of continuous and intermittent intramuscular administration of ketorolac. Br J Anaesth 67:235-238, 1991 13. Busoni P, Andreuccetti T: The spread of caudal analgesia in children: A mathematical model. Anaesth Intensive Care 14:140, 1986 14. Cote CJ: NPO after midnight for children-A reappraisal. Anesthesiology 72:589592,1990 15. Dalens BJ: Historical perspectives. In Pediatric Regional Anesthesia. Boca Raton, Florida, CRC Press, 1990, p 3 16. Dalens B, Tanguy A: Intrathecal morphine for spinal fusion in children. Spine 13:494498,1988 17. Dodge RR, Brown B: The prevalence and incidence of asthma and asthma-like symptoms in a general population sample. Am Rev Respir Dis 122:567,1980 18. Dubowitz L, Dubowitz V, Goldgerg C: Oinical assessment of gestational age in the newborn infant. J Pediatr 77:1-10, 1970 19. France NK, Beste OJ: Anesthesia for pediatric ear, nose, and throat surgery. In Gregory GA (ed): Pediatric Anesthesia. New York, Churchill Livingstone, 1989, pp 1122-1130 20. Friesen RH, Honda AT, Thieme RE: Changes in anterior fontanel pressure in preterm neonates during tracheal intubation. Anesth Analg 66:874-878, 1987 21. Gonzalez Alvarez MI, Reig del Moral C, Herrera Martin M, et aI: Value of routine preoperative tests in children. An Esp Pediatr 23:26-30, 1985 22. Goudsouzian NG, Alifimoff JK, Eberly C, et al: Neuromuscular and cardiovascular effects of mivacurium in children. Anesthesiology 70:237-242, 1989 23. Goudsouzian NG, Alifimoff JK, Liu LM, et al: Neuromuscular and cardiovascular effects of doxacurium in children anaesthetised with halothane. Br J Anaesth 62:263268,1989 24. Goudsouzian NG, Morris RH, Ryan JF: The effects of a warming blanket on the maintenance of body temperatures in anesthetized infants and children. Anesthesiology 39:351-353, 1973 25. Gough MM: Perioperative deaths among children. Br Med J 300:1606, 1990 26. Kaplan EB, Scheiner LB, Boeckmann AJ, et al: The usefulness of preoperative laboratory screening. JAMA 253:3576-3581, 1985 27. Koman LA, Urbaniak JR: Ulnar artery insufficiency: A guide to treatment. J Hand Surg [Am] 6:16-24, 1981
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28. Kurth CD, Spitzer AR, Broennie AM, et al: Postoperative apnea in preterm infants. Anesthesiology 66:483-488, 1987 29. Lagarde MRG, Poppers PJ: Stellate ganglion block: A therapeutic modality for arterial insufficiency of the arm in premature infants. Anesthesiology 61:203-204, 1884 30. Littleford JA, Patel LR, Bose D, et al: Masseter muscle spasm in children: Implications of continuing the triggering anesthetic. Anesth Analg 72:151-160, 1991 31. Liu LMP, Cote q, Goudsouzian NG, et al: Life threatening apnea in infants recovering from anesthesia. Anesthesiology 59:506-510, 1983 32. Lloyd-Thomas AR: Pain management in pediatric patients. Br J Anaesth 64:85-104, 1990 33. Macmillan RR, West DM, Desai KM: Brachial plexus block in upper limb ischemia. Anaesthesia 37:215-216, 1982 34. Maltby JR, Sutherland AD, Sale JP, et al: Preoperative oral fluids: Is a five-hour fast justified prior to elective surgery? Anesth Analg 65:1112-1116, 1986 35. Matthews AJ, Vernon JM: Masseter spasm in Williams syndrome. Anesthesia 46:706, 1991 36. Mason DG, Bingham RM: The laryngeal mask in children. Anaesthesia 45:760-763, 1990 37. Motoyama EK: Safety and outcome in pediatric anesthesia. In Motoyama EK, Davis PJ (eds): Smith's Anesthesia for Infants and Children. St Louis, CV Mosby, 1990, pp 847-856 38. Mowbray MJ, Gaukroger PB: Long-term patient-controlled analgesia in children. Anaesthesia 45:941-943, 1990 39. Neuman GG, Weingarten AE, Abramowitz RM, et al: The anesthetic management of the patient with an anterior mediastinal mass. Anesthesiology 60:144-177, 1984 40. O'Connor ME, Drasner K: Preoperative laboratory testing of children undergoing elective surgery. Anesth Analg 70:176-180, 1990 41. O'Hara DA, Fragen RJ, Kinzer RN, et al: Ketorolac tromethamine as compared with morphine sulfate for treatment of postoperative pain. Clin Pharmacol Ther 41:556561, 1987 42. Parris WCV, Reddy BC, White HW, et al: Stellate ganglion blocks in pediatric patients. Anesth Analg 72:552-556, 1991 43. Partridge BL: Use of pulse oximetry as a noninvasive indicator of intravascular volume status. J Clin Monit 3:263-268, 1987 44. Roy WL, Lehrman J, McIntyre BG: Is preoperative hemoglobin testing justified in children undergoing minor elective surgery? Can J Anaesth 38:700-703, 1991 45. Sanchez V, Segedin ER, Moser M, et al: Role of lumbar sympathectomy in the pediatric intensive care unit. Anesth Analg 67:794-797, 1988 46. Sandhar BK, Goresky GV, Maltby JR, et al: Effects of oral liquids and ranitidine on gastric volume and pH in children undergoing outpatient surgery. Anesthesiology 71:327-330, 1989 47. Scherpereel P: Analgesie controlee par Ie patient (ACP) (patient-controlled analgesia). Ann Fr Anesth Reanim 10:269-283, 1991 48. Schreiner MS, Triebwasser A, Keon TP: Ingestion of liquids compared with preoperative fasting in pediatric patients. Anesthesiology 72:593-597, 1990 49. Sibert KS, Biondi JW, Hirsch NP: Spontaneous respiration during thoracotomy in a patient with a mediastinal mass. Anesth Analg 66:904-907, 1987 50. Splinter WM, Stewart JA, Muir JG: The effect of preoperative apple juice on gastric contents, thirst and hunger in children. Can J Anaesth 36:55-58, 1898 51. Stewart DJ: Preterm infants are more prone to complications following minor surgery than term infants. Anesthesiology 56:304-306, 1982 52. Tait AR, Ketcham TR, Klein MJ, et al: Perioperative respiratory complications in patients with upper respiratory tract infections. Anesthesiology 59:A433, 1983 53. The American Society of Anesthesiologists: Standards for Basic Intra-operative Monitoring, 1991. Park Ridge, Illinois, The American Society of Anesthesiologists, 1991 54. Tobias JD, Deshpande JK, Wetzel RC, et al: Postoperative analgesia: Use of intrathecal morphine in children. Clin Pediatr 29:44-48, 1990 55. Tobias JD, Haun SE, Helfaer M, et al: The use of continuous caudal block to relieve lower-extremity ischemia caused by vasculitis in a child with meningococcemia. J Pediatr 115:1019-1021, 1989
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56. Ungerleider RM, Greeley WI, Sheikh KH, et al: Routine use of intraoperative epicardial echo and Doppler color imaging to guide and evaluate repair of congenital heart lesions: A prospective study. } Thorac Cardiovasc Surg 100:297-309, 1990 57. van der Walt }H, Carter }A: The effect of different preoperative feeding regimens on plasma glucose and gastric volume and pH in infancy. Anaesth Intensive Care 14:352-359, 1986 58. Valley RD, Bailey AG: Caudal morphine for postoperative analgesia in infants and children: A report of 138 cases. Anesth Analg 72:120-124, 1991 59. Vater M, Wandless }: Caudal or dorsal nerve block? A comparison of two local anesthetic techniques for postoperative analgesia following day case circumcision. Acta Anaesthesiol Scan 29:175-179, 1985 60. Vegfors M, Sjoberg F, Tryggvason B, et al: Assessment of peripheral blood flow using a pulse oximeter. } Clin Monit 6:1-4, 1990 61. Webster AC, McKishnie }D, Keynon CF, et al: Spinal anaesthesia for inguinal hernia repair in high-risk neonates. Can} Anaesth 38:281-286, 1991 62. Wolf AR, Hughes D, Hobbs A}, et al: Combined morphine-bupivacaine caudals for reconstructive penile surgery in children: Systemic absorption of morphine and postoperative analgesia. Anaesth Intensive Care 19:17-21, 1991 63. Yee}p, Koshiver }E, Allbon C: Comparison of intramuscular ketorolac tromethamine and morphine sulfate for analgesia after major surgery. Pharmacotherapy 6:253-261, 1986 64. Yeoman PM, Cooke R, Hain W: Penile block for circumcision? A comparison with caudal blockade. Anaesthesia 383:862-866, 1983
Address reprint requests to Edmond C. Bloch, MB, ChB, FFARCS Division of Pediatric Anesthesiology Department of Anesthesiology Room 3409 Duke University Medical Center Durham, NC 27710
PEDIATRIC SURGERY
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UPDATE ON ANESTHESIA MANAGEMENT FOR INFANTS AND CHILDREN Edmond C. Bloch, MB, ChB, FFARCS
During the past decade, pediatric anesthesia has matured into an important subspecialty of anesthesia. Major texts have appeared, and the literature has grown remarkably. Journals and societies devoted to the specialty have been established, and training to high standards is available in leading institutions in Europe and North America. The fully trained pediatric anesthesiologist is board certified in anesthesiology and has had a year or more of fellowship training in pediatric anesthesia. Many such physicians are also board certified in pediatrics and intensive care. THE OUTCOME
Despite this development, Motoyama, in an interesting review, 37 points out that the mortality rate relating to anesthesia in children is three to four times greater than in the general population. This ratio has not changed in 30 years. The dominant causes continue to be hypoxia related to airway or pulmonary complications and inappropriate management of fluids and blood volume. These are not the inevitable consequences of anesthesia, are eminently preventable, and are largely the result of human error. Unfortunately, all human beings, irrespective of ability and experience, make errors. 3 It is also obvious to any interested observer that many trained anesthesiologists who are otherwise very proficient are uncomfortable and indeed incompetent when it comes to dealing with children. It seems that the reasons for this are inadequate training and experience. This was emphasized in a review of perioperative deaths among children, which is subtitled "Standards of care are high, but those who don't care for children regularly shouldn't care for them at all."25 From the Division of Pediatric Anesthesiology, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
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PREOPERATIVE CONSIDERATIONS What Investigations?
What preoperative investigations are needed for anesthesia? This question often arises in the surgical clinic. A succinct history and physical examination are routine. Beyond that, in the absence of specific indications, routine laboratory tests have been found to contribute little to patient care and could reasonably be eliminated. 21 , 26 Certainly, routine urinalysis is in this category. 40 Nevertheless, most anesthesiologists would, as a minimum, probably require a hematocrit value in otherwise healthy children. Roy et al" reviewed the value of routine preoperative testing in pediatric patients and concluded that healthy patients aged 5 years and older Who are scheduled for minor surgery do not require routine hemoglobin determinations. They also questioned the value of such determinations in children aged 1 to 5 years. Communication between surgeon and anesthesiologist would, as always, be advisable to avert lastminute problems. Cough and Rhinorrhea
The child with a history of a recent fever, cough, and rhinorrhea raises doubts about the wisdom of embarking on anesthesia for elective surgery. Is this picture the precursor of a serious illness (e.g., measles, meningitis), a viral infection, or simply an allergy? The immediate concerns of the anesthesiologist are threefold. First, an irritable upper respiratory tract predisposes to cough and to laryngospasm with hypoxia during both induction and emergence. Second, the likelihood of postoperative complications (retention of secretions, atelectasis, pneumonia) is significantly increased. Finally, a generalized viral syndrome may affect the myocardium, occasionally resulting in a fatal dysrhythmia. A helpful guide to assessment is provided by the parent's response to the question: "Has your child been sick?" Symptoms such as lethargy, loss of appetite, somnolence, sweating, and abnormal behavior would, in the author's opinion, support postponement of the operation, as would an elevated body temperature and an abnormal white cell evaluation. On the other hand, some 15% to 20% of the population suffers from some type of respiratory allergy.l7 This and other conditions such as chronic sinusitis causing a nasal discharge are not contraindications to elective surgery. The surgical procedure must be considered. As an example, a poor candidate would be one for thoracic or abdominal surgery because of the reluctance or inability to cough effectively postoperatively, whereas this would not apply to a minor procedure on a limb. The postponement of surgery creates a hardship for the family. They may have traveled a long way to the hospital, and the parents may have taken time off from work and may not be able to do so soon again. They also may not be able to again afford the time and expense of travel and overnight lodgings. All these factors are of concern to the anesthesiologist, although the patient's welfare remains the primary consideration. If the decision is made to postpone the procedure, it would be wise to reschedule it for no sooner than 2 full weeks after the disappearance of symptoms. In fact, one study suggests that it is during this period that complications can be most troublesome. 52 A thoughtful and comprehensive review by Berry is recommended for further reading. 6
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NPO Status
Prolonged starvation and dehydration (NPO) should no longer be condoned in the management of the child awaiting surgery and anesthesia. A recent study 48 has indicated that clear fluids given up to 2 hours before induction of anesthesia do not increase the risk of pulmonary aspiration in children. As pointed out by the accompanying review,14 this has the additional benefit of avoiding the induction of anesthesia in a hypovolemic and hypoglycemic patient. Other studies 34, 46, 48, 50, 57 found no difference in gastric pH or residual volume between those patients who fasted for 8 or more hours versus those who fasted for 2 or 3 hours. This finding has led several pediatric anesthesia services, including our own, to alter their NPO requirements. These studies and their outcome do not apply to the patient with a disease process that predisposes to a "full stomach" and vomiting (e.g., trauma, shock, ileus, peritonitis, bowel obstruction) or to gastroesophageal reflux. In these patients, preoperative intravenous hydration, a 4- to 6-hour NPO period, and pretreatment with ranitidine 2.0 mglkg and 0.3 M sodium citrate (Bicitra) 0.5 mllkg orally is advisable. Premedication
The child's aversion to "needle sticks" has resulted in various premedication strategies ranging from none at all through pharmacologic methods to parental support only. Preoperative atropine, considered an essential when ether was in vogue, is now used selectively by some and often routinely omitted by others. Sedation and anxiolysis can be achieved by the nasal, oral, and rectal routes. Innovations include fentanyl lollipops and midazolam candy; these drugs can also be administered nasally and, in the case of midazolam, rectally. The Parent at Induction
For some years, it has been our practice to allow a parent to be present during induction of anesthesia in children over 6 months of age. Pediatric psychologists agreed that this age restriction was reasonable, as young infants easily take to an appropriate stranger and seem unaffected by separation from the parent. We have no upper age limit to this practice but have found that most older adolescents are happy to proceed without a parent present. In our experience, the child benefits enormously from the comfort, reassurance, and emotional support provided by the parent (Fig. 1). As a consequence, we have been able to abolish pharmacologic premedication with all its uncertainties and timing difficulties. The occasional parent declines the privilege, but most are appreciative of it, and we have had no inappropriate behavior on the part of the parent or other untoward incidents. Mediastinal Masses
A child with a mediastinal mass may present for cervical lymph node biopsy to establish a diagnosis or for excision of the mass. Case reports in the anesthetic literature 35 describe the problems encountered, and some document
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Figure 1. The child readily accepts the mask while being comforted by the mother.
intraoperative deaths. 39 One component of the problem is compression of the intrathoracic airways by the bulk of the mass any time during anesthesia or during emergence. This pressure is associated with loss of respiratory muscle tone, particularly after the use of muscle relaxants. Airway obstruction may be partial or complete. The other component of the problem is right ventricular outflow obstruction or pulmonary artery compression. Spontaneous ventilation should be preserved whenever possible. In the event of difficulties, a change in patient position or intubation with a rigid bronchoscope should be considered. Timely preoperative consultation with the anesthesiologist is mandatory to establish risk factors and to decide on the best course of action. A history of dyspnea on exertion or related to posture is very significant. Examination of the lung fields may reveal abnormal breath sounds. The intrathoracic airway must be evaluated by pulmonary function tests including flow-volume loops in the supine and upright positions, which are the most sensitive indicators of airway obstruction. Chest radiography (anteroposterior and lateral views) and a CT scan are also needed. If the anesthesiologist considers the hazards of general anesthesia to be prohibitive, an alternate treatment strategy will be required. This may be either biopsy using local anesthesia or radiation therapy or chemotherapy to reduce tumor bulk. If these are not possible or acceptable, consideration will have to be given to general anesthesia with rigid bronchoscopy and cardiopulmonary bypass standby.
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MONITORING Pulse Oximetry
In the past, the anesthesiologist relied on cyanosis or bradycardia to be alerted to hypoxemia. Much earlier warning is now provided by the pulse oximeter, which has been shown in many studies to provide a high degree of accuracy. Additionally, changes in the amplitude of the bar graph or in the waveform provide evidence of vasoconstriction or vasodilation. This is useful in the evaluation of intravascular volume status." In addition, vasodilatation resulting from sympathetic blockade is useful evidence of the onset of supplementary regional analgesia in an anesthetized child 60 following procedures such as spinal and epidural analgesia or stellate ganglion and axillary plexus blocks. Pulse oximetry is probably the most significant technologic advance in pediatric anesthesia and intensive care in the last decade. Failure to use pulse oximetry in the operating room, in the postanesthesia care unit, in the intensive care area, and during the transport of sick pediatric patients would be very difficult to justify. The American Society of Anesthesiologists, in publishing Standards for Basic Intra-operative Monitoring,53 effective on January 1, 1991, states that "a quantitative method of assessing oxygenation such as pulse oximetry shall be employed." The same body also "encourages" the use of capnography to confirm correct placement of the endotracheal tube and for monitoring of the adequacy of ventilation. This facility now is often combined with the monitoring of the concentration of anesthetic gases and vapors by infrared analysis or mass spectrography. Intraoperative transesophageal echocardiography to monitor cardiac function is currently of very limited use in pediatric patients. Small probes are being developed, but at present, the smallest ones are too large to be used in children weighing less than 25 to 30 kg (Fiona Clements, MD, personal communication, December 1991). In cardiac surgery, epicardial echo and Doppler color flow imaging have been found useful. 56 Automated Data Acquisition
Record keeping is an essential part of anesthesia monitoring. In some respects, manually generated records are self-defeating in that they distract the anesthesiologist from patient observation while data are being entered. Many such records are illegible, untidy, crowded with acronyms and abbreviations, and indecipherable to the point of being useless. Automated computer-generated record-keeping systems have developed to the extent that they are considered cost effective and efficient. They are being installed in major institutions as part of the hospital's data retrieval and storage system and are legally acceptable. INDUCTION OF ANESTHESIA Anesthetic Agents
Propofol (Diprivan) is a new intravenous induction agent. Its main attraction is that recovery is more rapid and complete than after pentothal, and it is therefore useful for short procedures and for ambulatory anesthesia. New
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muscle relaxants (alcuronium and vecuronium) have properties that make it possible to avoid the undesirable effects of the older products. The relaxant of choice for patients with renal or hepatic insufficiency is alcuronium, because its degradation is by other metabolic pathways. Vecuronium is useful in highrisk patients or in patients with a history of allergies because it does not stimulate histamine release and has no effect on hemodynamic parameters. Two recently introduced non-depolarizing muscle relaxants, doxacurium23 and mivacurium,22 have not yet gained widespread acceptance. The search for an ultra-short-acting non-depolarizing muscle relaxant to replace succinylcholine has made progress in that the newer ones mentioned above have a shorter duration of action than pancuronium or curare. Masseter Spasm and Malignant Hyperthermia
Masseter spasm following the administration of succinylcholine for tracheal intubation presents as resistance to passive opening of the mouth prior to laryngoscopy. It may be the result of too small a dose of the relaxant,35 but its association with malignant hyperthermia remains suspect and is widely debated. 3O Some anesthesiologists may elect to postpone the procedure pending investigation of the patient for malignant hyperthermia. Others mayor may not administer dantrolene before proceeding with the anesthetic with a heightened awareness and with meticulous monitoring. Malignant hyperthermia remains one of the pediatric anesthesiologist's most serious concerns. Enthusiastic research in both Europe and the United States aims at elucidating the etiology and also finding a noninvasive diagnostic test to replace the halothane-caffeine contracture test, which is available at relatively few centers and requires the patient's presence for a muscle biopsy. Expert advice for dealing with a case is available through a hotline maintained by The Malignant Hyperthermia Association (MHAUS; phone number 209-6344917).
ENDOTRACHEAL INTUBATION Awake Intubation
Awake intubation in the neonatal infant is performed as a routine by some anesthesiologists. Others will reserve it for the neonate who is at risk of regurgitation and aspiration, or when they are confronted with an airway known to be or seemingly difficult. The technique has fallen into disrepute with the realization that it is accompanied by hypertension and an increase in intracranial pressure,20 which may result in intraventricular hemorrhage in the newborn. Newer Aids to Intubation
Newer methods have been described for dealing with the difficult pediatric airway.19 Most are the result of advances in technology, which have produced the pediatric version of the Bullard laryngoscope 7 (Fig. 2, Circon Corporation, Stamford, Connecticut), the light wand1 (Fig. 3, Aaron Medical Industries, St. Petersburg, Florida), and flexible fiberoptic bronchoscopes of 2.2-mm external
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Figure 2. The Bullard laryngoscope. 7
diameter suitable for use with a 3.0-mm inner-diameter endotracheal tube (Olympus Corporation, Lake Success, New York). The light wand is a flexible lighted stylet that is inserted down an endotracheal tube (a 5.5 mm inner diameter is the smallest that can be used with it). In a darkened room, the assembly is passed down the anesthetized pharynx and, guided by transillumination of the tissues of the neck, advanced through the glottis, whereupon
Figure 3. The light wand.'
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the endotracheal tube is advanced over the wand into the trachea, and the wand is withdrawn. The laryngeal mask airway (Fig. 4, Colgate Medical, Reading Barks, England) has become popular since Brain described it in 1983. 8 It was approved for use in the United States in late 1991. It resembles a small anesthetic face mask, to which is attached a short length of tubing. It is introduced much like an oral airway and positioned in the hypopharynx just above the larynx. There is no need to visualize the glottis or to insert an endotracheal tube, and, in one of its four sizes, the mask can be used with both spontaneous and controlled ventilation for all patients more than a few weeks of age. 36 THERMAL REGULATION
Metabolic heat production is not depressed by anesthesia unless the patient is paralyzed, when it is reduced by approximately 25%. However, thermal regulation is affected by anesthesia and the circumstances surrounding it, such as exposure of the patient to cold operating rooms and surfaces and during transportation to and from the operating suite. All are not agreed on the efficacy of the various measures used to preserve thermal balance. Heated humidified inspired gas mixtures do not contribute much, but they are of significant benefit in preserving ciliary and bronchomotor function and in liquefying secretions. The blanket circulating warm water under the patient has been shown not to be useful in patients weighing more than 10 kg;24 in fact, it would seem better to place the blanket over the patient when possible. Overhead heating by infrared lights is not as effective as simply covering the patient with a sheet or blanket, which will reduce the heat lost by convection and radiation to surrounding cold surfaces. To be avoided is the unnecessary exposure of the patient during transport and during induction of anesthesia and surgical preparation, as well as of the viscera during surgery.
Figure 4. The laryngeal mask airway.8
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It is generally agreed that the lower quarter of the esophagus is the best site for obtaining temperature measurements. If it is iriaccessible, the nasopharynx may be used. Rectal temperature probes are best avoided; perforation of the rectum by a temperature probe has been reported in the neonate, and we have seen one such case with a fatal outcome in our hospital. REGIONAL ANESTHESIA
Bier, in 1889, was the first to publish a study of the use of regional anesthesia in children. His techniques gained enthusiastic acceptance for several years but progressively fell into disuse, and by the end of the Second World War, regional anesthesia in children had been almost completely abandoned. IS The conscious child was, and still is, a poor candidate for regional anesthesia because most children have a healthy fear of needles, and it is extremely difficult if not impossible to place the needle accurately in a frightened child in whom the margin for error is small. However, the modern pediatric anesthesiologist has safer and more effective means of dealing with this situation, and the past few years have seen a reintroduction and expansion of the use of regional anesthesia in children. For Surgical Procedures
When used as a component of general anesthesia, epidural or spinal anesthesia reduces or may even abolish the stress response to surgery and permits a reduction in the amount of anesthetic agent used; this shortens recovery time. If used in this way for abdominal procedures, regional anesthesia provides a measure of muscle relaxation and will also, by autonomic blockade, markedly reduce bowel distention during surgery. It reduces the incidence of postoperative nausea and vomiting, and it provides a very effective way of managing immediate postoperative pain without the side effects of narcotics (respiratory depression, urinary retention, nausea and vomiting, pruritus). There is the additional benefit of facilitating postoperative physical therapy and other procedures applied for the reduction of postoperative complications. The disadvantages of regional anesthesia include the extra time needed to perform the procedure and to allow it to become effective, the technical skill and dexterity required, and the fear of complications and legal ramifications. Absolute contraindications are the absence of consent by the parent or patient, progressive neurologic disease, coagulopathy, local infection, and anatomic aberrations. The maximum doses for infiltration when performing peripheral nerve blocks or field blocks are lidocaine 4 to 6 mg/kg and bupivacaine 2.5 to 3.0 mg/kg. The higher doses are for use only with epinephrine 1:200,000,62 which must not be used for the penis or the digits. Spinal Anesthesia
Subarachnoid block ("spinal anesthesia") is used mostly for inguinal hernia repair in the formerly premature infant with bronchopulmonary dysplasia. In patients with bronchopulmonary dysplasia, this technique is attractive in that general anesthesia and endotracheal intubation are avoided. Interestingly, these infants are not prone to the hypotension seen in older children and adults
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following subarachnoid block, but they are, like other children in their clinical category, at risk to develop postoperative apneic spells. A recent report"' describes disturbing complications in that, of 45 patients, 20 required supplementary general anesthesia, 6 required assisted ventilation perioperatively, and 5 had apneic spells postoperatively. Epidural Anesthesia
Caudal epidural anesthesia is often used to supplement general anesthesia and to provide postoperative anesthesia below the umbilicus. Above this level, lumbar or thoracic epidural anesthesia is preferred. Specially designed pediatric kits are available for these techniques. Some complications of regional anesthesia that may concern the surgeon include vomiting and urinary retention. Busoni and Andreuccetti,'3 in their series of 763 caudal epidural anesthesia cases, found no urinary retention and vomiting in only 5% of patients, whereas two other groups59, 64 report a 30% incidence of vomiting in series totalling 88 caudal epidural anesthetics. Vomiting13 and urinary retention58 occur more frequently when morphine is added to the local anesthetic mixture.62 Therapeutic Applications
The sympathetic blockade resulting ftom regional anesthesia has been used to treat upper 2• and lower limb ischemia in patients with meningococcal septicemia,>' 55 chronic vascular disease/7 vasospasm following trauma33 or vascular cannulation in the intensive care unit 45 or radiology department, and accidental intra-arterial injection. 5 Stellate ganglion blockade may control lifethreatening tachydysrhythmia. 42 POSTOPERATIVE CONSIDERATIONS Nausea and Vomiting
Postoperative nausea or vomiting may be anticipated in about 10% of patients. It is more likely in the patient who has experienced it after a previous anesthetic and following certain procedures (abdominal or strabismus surgery). It is seen more frequently between the ages of 3 and 5 years. Current prophylaxis is by the intravenous administration of droperidol 0.02 mg/kg on induction" and intravenous metoclopramide 0.15 mg/kg on arrival in the recovery area. 10 Postoperative Apnea
Life-threatening postoperative apnea has been identified in young, formerly premature infants after they have received general anesthesia,3l, 52 and it is more likely to occur in those with a history of apneic spells. Infants are considered to have been born prematurely when they have been born at less than 37 weeks of gestation, as determined by a Dubowitz evaluation' • at birth. The postconceptional age at which postanesthesia apnea ceases to be a concern ranges from 44 to 60 weeks, with no clear agreement. In our institution, preterm
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infants who are younger than 60 weeks' postconceptional age28 when subjected to general or regional anesthesia must be monitored continuously for at least 12 hours postoperatively. If the infant has a postoperative apneic event during that time, monitoring must be continued until at least 12 apnea-free hours have elapsed. These patients, sometimes admitted as day cases, must remain in the hospital overnight or longer if necessary. In the term infant, postoperative apnea is not common, but if there is a history of apnea, these infants should be dealt with in the same way as the ex-preemie. PAIN MANAGEMENT Divine is the work to overcome pain. HIPPOCRATES (460-370 BC)
A thorough review by Lloyd-Thomas32 is recommended to those interested in the problem of postoperative pain. We are reminded of the unfounded belief that the magnitude of the response to pain in children, especially in infants and neonates, is not as great as in adults. The justification for this erroneous assumption is the fear of administering suitable analgesics in adequate doses, of errors in dosage, of cardiovascular or respiratory depression, and of depressed levels of consciousness. Evidence that pain is underrated and undertreated in children is therefore not surprising. There has been an increasing amount of scientific evidence that neonates respond to pain. Arnand and Hickey, in an excellent review,' cite neuroanatomic, neurochemical, hormonal, metabolic, physiological, and behavioral evidence to support this. New Techniques
New routes for the administration of drugs have been described, together with their efficacy and complications. These techniques include the transmucosal, nasal, buccal, and trans dermal routes for the administration of fentanyl, sufentanil, and midazolam. The neuraxis provides two routes for pain management. Epidural bupivacaine will prOvide 4 to 6 hours of analgesia; this can be extended for as long as 20 hours by the addition of morphine, although possibly at the cost of a higher incidence of vomiting. 59, 64 Intrathecal morphine provides prolonged analgesia after procedures as diverse as exploratory laparotomy, craniofacial reconstruction,54 and spinal fusion. '6 Respiratory depression following epidural or intrathecal opiates in children is unpredictable, and its incidence varies. Valley and Bailey58 reviewed 136 patients who had received epidural caudal morphine and found that respiratory depression increases with higher doses (0.075-0.100 mglkg) and is more frequent under 1 year of age. They found the incidence of side effects (dose 0.070 mg/kg) to be urinary retention 51%, of whom 70% needed catheterization; vomiting 7.7%; and pruritus 3.1%. Respiratory monitoring in an intensive care setting for as long as 24 hours is strongly advised for every pediatriC patient who receives opiates via the epidural or intrathecal routes. Patient-controlled Analgesia
A good description of patient-controlled analgesia is provided by Scherpereel.·7 This is a drug delivery system for the control of acute pain using
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negative feedback technology in a closed loop system in which the patient plays an active role. It overcomes the problems of the traditional analgesic protocol, which is not suited to all patients because of individual differences in drug pharmacokinetics and pharmacodynamics. It also eliminates the underprescribing of opiates by physicians in pediatric patients for fear of dangerous side effects. Safe and effective delivery of these drugs on patient demand can be achieved by using various intravenous delivery systems, modes, and dosing parameters. The device is programmed by the physician to provide on-demand dosing (where a constant predetermined dose is self administered) or a constant minimum-rate ("background") infusion plus on-demand dosing. The physician also sets the incremental dose per demand, the lockout interval, and the maximum dose per unit of time. There is no doubt that patient-controlled analgesia provides better pain management. The patient or parent is given decisional control, relief is almost immediate and independent of nurse availability, and opiate requirements are decreased. Patients often choose less than the available total dose of analgesic, thereby balancing pain relief against side effects. Morphine sulfate and meperidine (Demerol) have been approved for patient-controlled use, but other drugs have been used. In most children over 5 years of age, patient-controlled analgesia can replace intramuscular injections. Mowbray and Gaukroger38 describe its satisfactory use in three older children for as long as 41 days, during which time no patient developed tolerance or clinical signs of dependence. The principles of demand analgesia are now being investigated using other agents such as local anaesthetics and via other routes, mainly the epidural space. Patientcontrolled analgesia and epidural opioids are fast becoming the methods of choice for the management of postoperative and long-term pain in children in many hospitals. A New Analgesic
The narcotics remain the primary analgesics, but because of their wellknown undesirable effects, the search for alternative agents continues. Ketorolac tromethamine (Toradol), at present not approved for use in children, is an inhibitor of prostaglandin synthesis and a powerful non-opioid analgesic. It is available in a syringe ready for intramuscular injection. Studies in adults have shown intramuscular ketorolac to be as effective as63 or even superior to41 intramuscular morphine after major surgery. When administered by continuous intramuscular infusion, it reduced patient-controlled morphine use by 49% .'2 There were no serious side effects, and ventilatory depression was insignificant when compared with that caused by morphine! SUMMARY
This review aims at providing the pediatric surgeon with an update on the most important issues in pediatric anesthesia and the changes that have taken place over the last few years. Many practices, entrenched in tradition, are being modified in the light of research that has provided new knowledge, drugs, and techniques. Pediatric anesthesia requires dedication, a sense of anticipation, meticulous attention to detail, and an individual who derives enormous satisfaction from the pleasure to be had from dealing with these small patients and their families.
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Address reprint requests to Edmond C. Bloch, MB, ChB, FFARCS Division of Pediatric Anesthesiology Department of Anesthesiology Room 3409 Duke University Medical Center Durham, NC 27710
