Outpatient
Inguinal
Herniorrhaphy
in Premature
Infants:
Is it Safe?
By John H. Melone, Marshall 2. Schwartz, Kenneth R.T. Tyson, Clifford C. Marr, Stephen K. Greenholz, Jay E. Taub, and Victor J. Hough
Sacramento, California 0 Because postoperative apnea and bradycardia in premature infants following inguinal herniorrhaphy remains a concern, outpatient repair has not been recommended. We have been performing outpatient inguinal herniorrhaphy in premature infants and the present study reviews our experience. Between 1985 and 1990,1,294 outpatient inguinal herniorrhaphies were performed. Gf this group 124 patients (9.6%) were identified as being premature ( 5 36 weeks gestational age). Average ages were: gestational age 32.7 weeks (range, 24 to 36 weeks); postnatal age 12.6 weeks (range, 3 to 24 weeks); and postconceptional age (gestational plus postnatal) 45.3 weeks (range, 34 to 59 weeks). Twenty-two infants previously required ventilatory support, 11 patients had apnea/ bradycardia, and 9 patients developed bronchopulmonary dysplasia. General anesthesia (usually nitrous oxide and fluothane) was used in all patients and 75% underwent endotracheal intubation. The average operating room time was 40 minutes (range, 20 to 115 minutes) and the average recovery room time was 94 minutes (range, 30 to 240 minutes). There were no perioperative deaths. One patient became apneic immediately after extubation in the operating room. No further episodes were noted after 4 hours of observation. Another patient following discharge had a brief apneic episode at home while on an apnea monitor, which was relieved with gentle stimulation. Both patients had no further sequelae. Bradycardia to 80 beats/min was noted in two patients, and resolved spontaneously in the recovery room. Laryngospasm after extubation in the operating room occurred in two patients, one of whom required brief reintubation and the other resolved spontaneously. Two patients required postoperative ventilation: one was extubated in the recovery room and the other was hospitalized for 24 hours. This series did not demonstrate the high postoperative incidence of apnea and bradycardia as previously reported. This was true even for those infants with a prior history of apnea and bradycardia. Although the reasons for the decreased incidence of apnea/bradycardia are unclear, it is important to note that preoperative and intraoperative narcotics were not used and muscle relaxation was infrequently used (14%). There was only one postdischarge emergency room visit and no patients required admission following discharge from the outpatient surgery center. On the basis of our experience, routine inpatient inguinal herniorrhaphy in infants born prematurely does not appear to be necessary. Outpatient inguinal herniorrhaphy can be performed in this patient group with minimal morbidity and no mortality. Copyright o 1992 by W.B. Saunders Company INDEX WORDS:
lnguinal herniorrhaphy
in premature
infants.
I
NGUINAL herniorrhaphy in infants generally is considered to be an outpatient surgical procedure. However, because of an increased incidence of apnea and bradycardia following general anesthesia in infants born prematurely, it has been recommended that inguinal herniorrhaphy be performed as JournalofPec/iarric
Surgery, Vol 27, No 2 (February),
1992:
pp 203-208
an inpatient procedure to allow postoperative observation for up to 24 hours.‘-’ Over the past several years we have been performing outpatient inguinal herniorrhaphy under general anesthesia in infants born prematurely. The present study reviews our experience with particular emphasis on safety and morbidity. MATERIALS AND METHODS From 19X5 to 1990. L,294 outpaitent inguinal herniorrhaphies were performed at a free-standing outpatient surgery unit. Of this group 124 patients (9.6%) were identified as being premature at birth (2 36 weeks gestational age) and this subgroup of infants forms the basis of this study. All socioeconomic circumstances were represented in this group. The medical records of these patients were reviewed and data were collected on birth and surgery weight, past medical history, hemoglobin level, American Society of Anesthesiologists (ASA) physical status class, anesthetic regimen. intubation, operating and recovery room time, and complications or side effects of anesthesia or surgery. Outcome and potential complications were accessed by telephone usually within 3 days of operation (average, 2.6 days; range, 1 to 10 days) using a standardized questionnaire, and by follow-up visit I to 2 weeks postoperatively. Follow-up was successful in 98% of the patients. The gestational, postnatal. and postconceptional ages, as well as birth weight data are shown in Table I and Fig 1.The past medical history and complications of prematurity arc shown in Table 2.
Status at the Time Technique
ofOperation and Anesthetic
At the time of inguinal herniorrhaphy. the average postconceptional age was 45.3 weeks (range, 34 to 59 weeks) and the average weight at operation was 4.485 g (range, 2.295 to 9.977 g). Note that 67 infants (54%) were below 46 weeks postconceptional age (Fig 1). The average hemoglobin was Il.6 g/dL (range. 7.5 to 16 g/dL). The ASA class as determined by the attending anesthesiologist was: class 1, 52%; class 11,48%. General anesthesia was used in all patients (Table 3) and administered by attending anesthesiologists. The most frequent inhalation anesthetic combinations were nitrous oxide and fluothane (60%) and nitrous oxide and forane (12%). Only 17 infants (14%) received a muscle relaxant. Endotracheal intubation was used in 93 patients (757~).
From the Department of SuGeger?i,Universi~ of Califomiu. Davis School of Medicine, and The Sutter Surgery Center. Sacramento, CA. Presented at the 22nd Annual Meeting of the American Pediatric Surgical Association, Lake Buena Vista, Florida, Mav 15-18. 1991. Address reprint requests to Marshall 2. Schwartz, MD. Department of Surgery. University of California, Davis Medical Center, 4301 X St, Sacramento, CA 95817. Copyright 0 1992 by W.B. Saunders Companv 0022.346819212702.0013$03.OOJO 203
MELONE ET AL
204
Table 1. Demographic Data Collected From the Medical Records of 124 Infants Born Prematurely Who Underwent
Table 2. Past Medical History in 124 Infants Born Prematurely Who
Outpatient
Underwent
Herniorrhaphy Average
Gestational age (wk) Postnatal age at surgery (wk) Postconceptional age at surgery (wk) Birth weight(g)
32.7 12.6 45.3 7.727
Range
24-36 3-24 34-59 453.3,401
Surgical Procedure Infants underwent either unilateral or bilateral inguinal herniorrhaphy. High ligation of the hernia sac was accomplished after dividing the external oblique fascia to gain exposure to the inguinal canal and separation of the hernia sac from the spermatic vessels and vas deferens. The average operating time was 40 minutes (range, 20 to 115 minutes).
Recovey Room Observation All patients were closely observed in the recovery room by vital signs including continuous heart rate monitoring. Apnea, bradycardia, or cyanosis were recorded when observed. Oral fluids were begun prior to discharge from the recovery room. RESULTS
There were no perioperative deaths in this series of patients. The postanesthesia/postoperative problems are summarized in Table 4. Because the number of these problems was small, no statistical correlation could be identified between the events and the presence of apnea preoperatively or the anesthetic regimen. Operating Room Outcome
One patient became apneic immediately after extubation. Spontaneous ventilation resumed following stimulation and reintubation was not required. This infant was observed for an additional 4 hours in the recovery room and did not have any further episodes of apnea. This same infant was brought to the emergency room 3 days following surgery for a
3 p!
16
II
14
= * r: .s h
12
6
6
8
4
No. of Patients
Prior ventilatory support
22
Apnea
11
Bradycardia
10
Bronchopulmonary dysplasia
9
Prior home apnea monior use
12
Asthma
4
Bronchitis
3
Pneumonia
8
Recent upper respiratory tract infection
4
presumed apneic episode. The infant was examined by the emergency room personnel, found to be normal, and discharged. Bradycardia to 80 beats/min was noted in one patient intraoperatively. This was transient and resolved quickly and spontaneously. Laryngospasm was observed in two patients following extubation in the operating room. One patient was briefly reintubated and subsequently extubated uneventfully in the recovery room. Laryngospasm in the other patient resolved spontaneously in the operating room. Two patients were noted to have respiratory difficulty following extubation in the operating room. One of these patients was reintubated in the operating room and subsequently extubated in the recovery room. A second patient was reintubated for possible aspiration following extubation. This infant was admitted for observation, uneventfully extubated 24 hours later, and discharged. This patient was the only one in the series of 124 patients who required postoperative hospitalization. Recovery Room Outcome
The average length of stay in the recovery room was 94 minutes (range, 30 to 240 minutes). One patient had a brief episode of bradycardia in the recovery room while sleeping. This was reversed by gentle stimulation and was without apparent sequelae. There were no other documented episodes of bradycardia noted in the charts for any of the remaining patients while in the recovery room. Table 3. Regimen Used for Anesthesia in 124 Infants Born
10
Prematurely Who Underwent
8
0
lnguinal Herniorrhaphy
AnestheticRegimen
$2 z’
lnguinal Herniorrhaphy
PastMedical History
3233343538373839404142434445404748485051525354555651 505D60 Postconceptional
Age (weeks)
Fig 1. Distribution of postconceptional ages (gestational age plus postnatal age) for 124 infants born prematurely who underwent inguinal herniorrhaphy.
No. of Patients
Nitrous oxide and fluothane
75
Nitrous oxide and forane
15
Nitrous oxidelfluothaneisuccinylcholine
11
Nitrous oxide/fluothane/forane
8
Fluothane
6
Nitrous oxide/forane/succinylcholine
4
Nitrous oxide/fluothane/atropine
3
Nitrous oxide/forane/succinyIcholine/atropine
2
OUTPATIENT
HERNIORRHAPHY IN PREMATURE INFANTS
Table 4. Postanesthesia-Related Herniorrhaphy
Problems Following lnguinal
in 8 Infants Born Prematurely NO.
Problem
of Patients
Outcome
Apnea
2
Resolved spontaneously.
Bradycardia
2
Resolved spontaneously.
Laryngospasm
2
Brief reintubation in 1 patient, the other patient resolved spontaneously.
Respiratory
2
difficulty
One patient was extubated in the recovery room. A second patient was reintubated, admitted for possible aspiration, and extubated 24 hours later.
Outcome Following Discharge One patient was noted to have a brief apneic episode at home several hours following discharge from the outpatient surgery center recovery room, which was relieved with gentle stimulation. This patient had a history of apnea, was on an apnea monitor prior to the surgery and remained on the apnea monitor following discharge from the surgery center. Thus, there were no patients who required hospitalization following discharge from the recovery room for any reason, including apnea or bradycardia. It is of note that with a 98% follow-up, only one patient had a documented episode of apnea within 24 hours of discharge from the outpatient surgery center recovery room. As noted previously, one patient was reintubated in the recovery room and hospitalized because of emesis and possible aspiration. No radiographic or clinical evidence of aspiration was noted and the patient was extubated successfully the following day and discharged. DISCUSSION An increasing percentage of extremely premature infants are able to survive because of marked improvements in neonatal care. One of the common sequela of prematurity is the development of an inguinal hernia.” Considerable debate has occurred regarding the appropriate timing and postoperative environment for inguinal herniorrhaphy in this unique group of patients.‘-5 Much of the concern has centered around the well-documented increased incidence of apnea associated with prematurity and following general anesthesia. In an article published in 1982, Steward’ noted that 12% of 33 infants born prematurely developed apnea up to 12 hours following general anesthesia. Two of these patients had had a prior history of apnea. Unfortunately, the specific time of the apnea episode following the completion of
205
anesthesia within this 1Zhour time frame was not identified for each patient. Apparently none of the patients with apnea required intubation. On the basis of his observations, Steward concluded that patients with a history of apnea, and particularly those under 46 weeks postconceptional age should be monitored for 24 hours postoperatively as an inpatient. In 1983 Liu et al2 evaluated 41 premature infants ( < 37 weeks gestation), 15 of whom had a preanesthetic history of apnea. Six of these 15 infants required prolonged ventilation following their operative procedure. Unfortunately, the length of ventilation or hospitalization was not stated. In addition, major surgical procedures were performed in 3 of the 6 patients who required prolonged ventilation. Thus, only 3 of 41 patients who were born premature and had inguinal herniorrhaphy required prolonged postanesthesia ventilation. Two of these patients were receiving theophylline for apnea preoperatively and the third patient received curare as one of the anesthetic agents, a medication known to increase the risk of postanesthesia apnea.’ On the basis of their experience Liu et al concluded that infants under 46 weeks postconceptional age and with a history of apnea, “should be admitted to the hospital postoperatively and closely monitored for 24 hours.“’ An editorial appearing in the same issue of AnesthesioZogy’ states that, “Based on the limited amount of information available, it is difficult to state with certainty that this is the correct conclusion.” However, these editorialists further state that unessential surgery for preterm infants less than 44 weeks postconceptional age should be delayed. When the operative procedure cannot be delayed, they recommended that the patients be hospitalized for postoperative observation for at least 18 hours. Rescorla and Grosfeld” reviewed their experience with inguinal herniorrhaphy in premature infants. Thirty infants were under 36 weeks gestational age. Two of the 30 premature infants required postoperative mechanical ventilation for apnea and bradycardia but the length of ventilation and hospitalization were not stated. On the basis of their experience they recommended that preterm infants requiring inguinal herniorrhaphy should be managed as inpatients and carefully observed postoperatively. Welborn et al’ evaluated 21 patients, (less than 37 weeks gestation at the time of birth) who subsequently underwent general anesthesia for inguinal herniorrhaphy. No episodes of apnea or bradycardia were identified. However, 8 patients developed “periodic breathing,” which they defined as apnea lasting 3 to 15 seconds separated by less than 20 seconds of normal breathing. Bradycardia was not associated with periodic breathing. All of these patients were less than 44 weeks
206
postconceptional age. None of their patients required prolonged intubation or mechanical ventilation. In a well-studied group of 47 preterm infants ( < 37 weeks gestation) who underwent general anesthesia before 60 postconceptional weeks, Kurth et al4 identified 18 patients who had prolonged (> 15 seconds) apnea following general anesthesia. Thirteen patients required only manual stimulation, and 4 patients had spontaneous recovery. Only one patient required reintubation for repeated prolonged apnea. Seventytwo percent of the patients had their initial apnea event within 2 hours of anesthesia. The authors concluded that “infants younger than 60 postconceptional weeks should be monitored continuously for at least 12 hours postoperatively.” In a 1987 report Mayhew et al5 evaluated 35 premature infants who underwent elective inguinal herniorrhaphy as inpatients. They noted that 4 patients required postoperative ventilation for apnea. Of note is that of the 7 infants who received pancuronium, 4 patients required postanesthesia ventilation. Unfortunately, the length of ventilation for these 4 patients was not stated in the publication. In reviewing the potential risk factors for postanesthetic apnea, the authors found that the best correlation was with a preoperative history of apnea or significant pulmonary disease. It is generally accepted that postanesthesia apnea is more likely to occur in infants born prematurely rather than at full term. On the basis of this observation and the articles cited above, it has been recommended that inpatient observation is necessary following general anesthesia for inguinal herniorrhaphy in infants born prematurely. However, on review of the information presented in these same publications, it is not clear that the data cited support the need for routine inpatient observation beyond the recovery room. The timing of the apnea episodes were not well defined in the patients cited in these articles. However, it would appear, based on available information contained in the articles, that the apnea episodes and other significant respiratory events occurred very soon after extubation, or that it was elected not to extubate the infant immediately following cessation of anesthesia because of documented apnea. The nondepolarizing muscle relaxant pancuronium was used in several of the patients cited in the literature that required prolonged intubation. It was pointed out both by Liu et al2 and Mayhew et al5 that pancuronium seemed to lead to a higher incidence of postanesthesia respiratory complications. The incidence of apnea was remarkably low in the present patient series. The basis for this is not entirely clear. However, pancuronium was not used, and the muscle
MELONE ET AL
relaxant succinylcholine was used in only 17 patients (of a total of 124 patients). In addition, preoperative and intraoperative narcotics were not used. It is important to note that the low incidence of apnea was in spite of the fact that 67 of the patients were less than 46 weeks postconceptional age, 28 of the patients were less than 41 weeks postconceptional age, and 11 patients had a previous history of apnea. It would seem logical to accept the recommendation that premature infants requiring inguinal herniorrhaphy be observed as inpatients postoperatively. However, one has to ask what benefits would be derived from inpatient observation in those infants that are extubated shortly after the completion of the operative procedure and appear to be doing well 1 to 2 hours later. Certainly, close observation by trained personnel using monitoring equipment can be advantageous. However, monitoring equipment such as apnea monitors are available for home use. These monitors were frequently used in our patient series. Although it may appear that trained personnel are necessary for postanesthesia observation, it has been our experience that those infants likely to require those skills (such as intubation) declare themselves early following surgery and anesthesia. In the majority of infants postanesthesia with delayed-onset apnea, stimulation alone is all that is necessary. In addition, hospital personnel are likely to lack familiarity with each patient’s breathing patterns, etc. In contrast, a reliable parent is familiar with his/her infant’s normal respiratory pattern and may well have had prior experience with apnea. We found that many of the families were familiar with apnea monitors because their infants were placed on them following hospital discharge. Perhaps the most relevant fact is that in our review of the literature we were not able to identify any patients that required intubation beyond two to three hours postanesthesia. In our own patient series none of the infants required admission to a hospital once they had been discharged from the outpatient recovery room. Finally, hospitalization is not without its own risks and one can not ignore the expense incurred with routine inpatient care following inguinal herniorrhaphy in this patient population. We believe that outpatient herniorrhaphy under general anesthesia can be a safe treatment plan for infants that are born prematurely. We base this conclusion primarily on our own experience, but also because of a lack of objective data in the literature to support the recommendation that 24-hour inpatient observation following general anesthesia for inguinal herniorrhaphy should be mandatory in infants born prematurely. However, we do not mean to imply that
OUTPATIENT
HERNIORRHAPHY
IN PREMATURE
207
INFANTS
all infants born prematurely will be candidates for outpatient herniorrhaphy, or that all outpatient surgical facilities should embrace this approach.
ACKNOWLEDGMENT The authors thank Ben Antonio and John Bringas for their assistance in data collection.
REFERENCES 1. Steward DJ: Preterm infants are more prone to complications following minor surgery than are term infants. Anesthesiology 56:304-306, 1982 2. Liu LMP, Cote CJ, Goudsouzian NG, et al: Life threatening apnea in infants recovering from anesthesia. Anesthesiology 59:506510,1983 3. Rescorla FJ. Grosfeld JL: Inguinal hernia repair in the perinatal period and early infancy: Clinical considerations. J Pediatr Surg 19:832-837. 1984 4. Kurth CD, Spitzer AR, Broennle AM, et al: Postoperative apnea in preterm infants. Anesthesiology 66:483-488, 1987
5. Mayhew JF, Bourke DL, Guinee WS: Evaluation of the premature infant at risk for postoperative complications. Can J Anaesth 34:627-631, 1987 6. Harper RG. Garcia A, Sia C: Inguinal hernia: A common problem of premature infants weighing 1000 gms or less at birth. Pediatrics 56:112-115, 1975 7. Gregory GA, Steward DJ: Life-threatening perioperative apnea in the ex-“premie.” Anesthesiology 59:495-498. 1983 8. Welborn LG, Ramirez N, Oh TH. et al: Evaluation of anesthetic risks in premature infants. Anesthesiology 61:A417. 1984 (abstr)
Discussion D.A. Cuniano (Columbus, OH): Since premature infants comprise upwards of 10% of patients requiring inguinal herniorrhaphy, their admission status certainly has clinical relevance to all of us in this room. In Columbus, we have also been concerned about this group of patients and we recently embarked on a perspective study which was conducted by Dr Daniel Teitelbaum, our pediatric surgical trainee. He collaborated with the members of our Anesthesiology Department and over a l-year period, they prospectively evaluated 40 full-term infants and 62 preterm infants with a postconceptual age of less than 60 weeks. They evaluated all patients with no selection criteria other than age. The infants were monitored continuously by pulse oximetry as well as a pneumocardiogram. The monitoring occurred in the recovery room, postrecovery room, and in the patient’s room for those infants who required hospitalization. Unfortunately, the preterm infants in Columbus, OH, do much more poorly than the infants in California. In our study, the authors concluded that two major problems occurred in the preterm infant. In the recovery room, there was a 28% incidence of significant apnea and bradycardia, which required vigorous stimulation in order to be relieved. More importantly, 20% of the preterm infants had a significant apneic event up to 4 to 10 hours following their operation. So this was well beyond the period of their discharge from the recovery room setting and all of these events occurred in the patient’s room. I have basically three questions for the authors. The discrepancy between the results in Columbus and the results you have given us today might be explained by a couple of factors. First of all, since you used a
retrospective analysis, could there have been some hidden prior selection criteria so that less healthy or vigorous preterm infants were excluded from being outpatients? Second, the infants in your study were monitored in the recovery room by vital signs and heart rate. Since pulse oximetry and pneumocardiograms were not used, could you have missed episodes of oxygen desaturation, apnea, or bradycardia because you did not employ these monitors? Third, your patients remained in the recovery room for up to 4 hours following operation, long enough to be given oral fluids. Is this routine practice in your hospital, since most of the major teaching centers are not staffed adequately in order to keep patients in the recovery room setting for this length of time? In conclusion, of most concern, I think, is your general recommendation that all preterm infants can be safely handled as outpatients. It would seem that several caveats need to be in place. First, a highly experienced group of anesthesiologists; second, acceptance of potential medicolegal liability because even one cardiorespiratory catastrophe could be disastrous in this patient population; and third, a unique outpatient facility would be necessary in order to achieve your excellent results. A. Browne (Portland, ME): I’m certainly glad you have brought this subject to our attention and I applaud your results. However, I think you need to explain to us how you did it. What did you do differently from all of the other anesthesiologists and surgeons in North America? Is there a difference in your anesthesia technique? If people are going to read this and say “I can go to the local surgicenter and have my hernia fixed,” we have to have a technique
208
that we can tell the surgicenter personnel about and you haven’t really pointed out what was the difference in what you did. K. Georgeson (Birmingham, AL): How long did the infants stay in their room before discharge? M. Gauderer (Cleveland, OH): I have one comment and one question. The comment is that prematurity is really a spectrum. We are seeing an increase in extremely low birth weight infants, children with a birth weight under 1,500 g are surviving. So I think it is very important to define the type of premature that we are really talking about. The question is what was the operating room time? The authors defined operating time but not the time in the operating room. I think that that can be markedly increased by operating on prematures. J. Langer (Hamilton, Ontario): Since both pain and pain control agents may affect the incidence of apnea in premature babies, I wonder if you could comment on what kind of analgesia was used in your series? J.C. German (Orange County, CA): Diller Groff reported about 10 years ago that these premature infants, as well as other infants with high-risk criteria, have longer operating and recovery room times. And, all of us know who assist residents in doing the tiny prematures that it just does take a longer time. Also these infants in our own experience tend to declare themselves on emergence from anesthesia in that they develop periodic breathing and they take a long time to extubate so that operating room time itself is really a lot longer in our experience. So this has to be looked at and it sounds like everybody is trying to look at the same thing. R. Pearl (Washington, D.C.): Which patients were excluded from this study? J. Melone (response): Dr Caniano, regarding the issue that you raised as did Dr Pearl, there was no selection process once the infants were discharged from the neonatal unit. Therefore, this is an inclusive rather than exclusive series. Your second question referred to possible missed episodes of oxygen desaturation. It is possible that very brief desaturation
MELONE ET AL
episodes may have occurred. However, they did not appear to be clinically significant either in the recovery room where the patients were monitored for apnea and bradycardia or at home. Regarding the question of oral fluids postoperatively, all of the infants were given oral fluids usually within 30 minutes of arrival in the recovery room. Finally, you asked if it is safe to treat all infants born prematurely that require inguinal herniorrhaphy in an outpatient unit. We would suggest that this be determined by individual judgement based on your assessment of the patient’s risk and the outpatient environment available to you. On the basis of our experience in our setting it was safe. Dr Brown asked what did we do differently regarding the anesthetic technique? The cause for our low incidence of postanesthesia apnea is not clear. However, attending anesthesiologists performed the anesthesia and they did not use narcotics preoperatively or intraoperatively. Also, in only 14% of infants did they use muscle relaxants. We are not sure if these factors led to our lower incidence of apnea and bradycardia. Previous publications have suggested that muscle relaxants, especially pancuronium, increase the risk of apnea. Dr Jorgesen, all infants were discharged directly home from the recovery room. Regarding your question on how we convinced our anesthesiologists: The outpatient facility that was used was one of the first free-standing units to be opened in the mid-1970s. Several of the anesthesiologists, already being pioneers, were willing to take on a new challenge. We had observed that inpatient herniorrhaphy in this group of patients did not seem necessary and suggested that we do them as outpatients. They agreed. Dr Gauderer, the operating room time as we reported it included the time from induction to completion of anesthesia. Dr Langer, Tylenol was used for pain control. Dr Hatch, we have done well with our approach and, therefore, have not felt a need to try other alternatives.
Inguinal
Herniorrhaphy
in Premature
Infants:
Is it Safe?
By John H. Melone, Marshall 2. Schwartz, Kenneth R.T. Tyson, Clifford C. Marr, Stephen K. Greenholz, Jay E. Taub, and Victor J. Hough
Sacramento, California 0 Because postoperative apnea and bradycardia in premature infants following inguinal herniorrhaphy remains a concern, outpatient repair has not been recommended. We have been performing outpatient inguinal herniorrhaphy in premature infants and the present study reviews our experience. Between 1985 and 1990,1,294 outpatient inguinal herniorrhaphies were performed. Gf this group 124 patients (9.6%) were identified as being premature ( 5 36 weeks gestational age). Average ages were: gestational age 32.7 weeks (range, 24 to 36 weeks); postnatal age 12.6 weeks (range, 3 to 24 weeks); and postconceptional age (gestational plus postnatal) 45.3 weeks (range, 34 to 59 weeks). Twenty-two infants previously required ventilatory support, 11 patients had apnea/ bradycardia, and 9 patients developed bronchopulmonary dysplasia. General anesthesia (usually nitrous oxide and fluothane) was used in all patients and 75% underwent endotracheal intubation. The average operating room time was 40 minutes (range, 20 to 115 minutes) and the average recovery room time was 94 minutes (range, 30 to 240 minutes). There were no perioperative deaths. One patient became apneic immediately after extubation in the operating room. No further episodes were noted after 4 hours of observation. Another patient following discharge had a brief apneic episode at home while on an apnea monitor, which was relieved with gentle stimulation. Both patients had no further sequelae. Bradycardia to 80 beats/min was noted in two patients, and resolved spontaneously in the recovery room. Laryngospasm after extubation in the operating room occurred in two patients, one of whom required brief reintubation and the other resolved spontaneously. Two patients required postoperative ventilation: one was extubated in the recovery room and the other was hospitalized for 24 hours. This series did not demonstrate the high postoperative incidence of apnea and bradycardia as previously reported. This was true even for those infants with a prior history of apnea and bradycardia. Although the reasons for the decreased incidence of apnea/bradycardia are unclear, it is important to note that preoperative and intraoperative narcotics were not used and muscle relaxation was infrequently used (14%). There was only one postdischarge emergency room visit and no patients required admission following discharge from the outpatient surgery center. On the basis of our experience, routine inpatient inguinal herniorrhaphy in infants born prematurely does not appear to be necessary. Outpatient inguinal herniorrhaphy can be performed in this patient group with minimal morbidity and no mortality. Copyright o 1992 by W.B. Saunders Company INDEX WORDS:
lnguinal herniorrhaphy
in premature
infants.
I
NGUINAL herniorrhaphy in infants generally is considered to be an outpatient surgical procedure. However, because of an increased incidence of apnea and bradycardia following general anesthesia in infants born prematurely, it has been recommended that inguinal herniorrhaphy be performed as JournalofPec/iarric
Surgery, Vol 27, No 2 (February),
1992:
pp 203-208
an inpatient procedure to allow postoperative observation for up to 24 hours.‘-’ Over the past several years we have been performing outpatient inguinal herniorrhaphy under general anesthesia in infants born prematurely. The present study reviews our experience with particular emphasis on safety and morbidity. MATERIALS AND METHODS From 19X5 to 1990. L,294 outpaitent inguinal herniorrhaphies were performed at a free-standing outpatient surgery unit. Of this group 124 patients (9.6%) were identified as being premature at birth (2 36 weeks gestational age) and this subgroup of infants forms the basis of this study. All socioeconomic circumstances were represented in this group. The medical records of these patients were reviewed and data were collected on birth and surgery weight, past medical history, hemoglobin level, American Society of Anesthesiologists (ASA) physical status class, anesthetic regimen. intubation, operating and recovery room time, and complications or side effects of anesthesia or surgery. Outcome and potential complications were accessed by telephone usually within 3 days of operation (average, 2.6 days; range, 1 to 10 days) using a standardized questionnaire, and by follow-up visit I to 2 weeks postoperatively. Follow-up was successful in 98% of the patients. The gestational, postnatal. and postconceptional ages, as well as birth weight data are shown in Table I and Fig 1.The past medical history and complications of prematurity arc shown in Table 2.
Status at the Time Technique
ofOperation and Anesthetic
At the time of inguinal herniorrhaphy. the average postconceptional age was 45.3 weeks (range, 34 to 59 weeks) and the average weight at operation was 4.485 g (range, 2.295 to 9.977 g). Note that 67 infants (54%) were below 46 weeks postconceptional age (Fig 1). The average hemoglobin was Il.6 g/dL (range. 7.5 to 16 g/dL). The ASA class as determined by the attending anesthesiologist was: class 1, 52%; class 11,48%. General anesthesia was used in all patients (Table 3) and administered by attending anesthesiologists. The most frequent inhalation anesthetic combinations were nitrous oxide and fluothane (60%) and nitrous oxide and forane (12%). Only 17 infants (14%) received a muscle relaxant. Endotracheal intubation was used in 93 patients (757~).
From the Department of SuGeger?i,Universi~ of Califomiu. Davis School of Medicine, and The Sutter Surgery Center. Sacramento, CA. Presented at the 22nd Annual Meeting of the American Pediatric Surgical Association, Lake Buena Vista, Florida, Mav 15-18. 1991. Address reprint requests to Marshall 2. Schwartz, MD. Department of Surgery. University of California, Davis Medical Center, 4301 X St, Sacramento, CA 95817. Copyright 0 1992 by W.B. Saunders Companv 0022.346819212702.0013$03.OOJO 203
MELONE ET AL
204
Table 1. Demographic Data Collected From the Medical Records of 124 Infants Born Prematurely Who Underwent
Table 2. Past Medical History in 124 Infants Born Prematurely Who
Outpatient
Underwent
Herniorrhaphy Average
Gestational age (wk) Postnatal age at surgery (wk) Postconceptional age at surgery (wk) Birth weight(g)
32.7 12.6 45.3 7.727
Range
24-36 3-24 34-59 453.3,401
Surgical Procedure Infants underwent either unilateral or bilateral inguinal herniorrhaphy. High ligation of the hernia sac was accomplished after dividing the external oblique fascia to gain exposure to the inguinal canal and separation of the hernia sac from the spermatic vessels and vas deferens. The average operating time was 40 minutes (range, 20 to 115 minutes).
Recovey Room Observation All patients were closely observed in the recovery room by vital signs including continuous heart rate monitoring. Apnea, bradycardia, or cyanosis were recorded when observed. Oral fluids were begun prior to discharge from the recovery room. RESULTS
There were no perioperative deaths in this series of patients. The postanesthesia/postoperative problems are summarized in Table 4. Because the number of these problems was small, no statistical correlation could be identified between the events and the presence of apnea preoperatively or the anesthetic regimen. Operating Room Outcome
One patient became apneic immediately after extubation. Spontaneous ventilation resumed following stimulation and reintubation was not required. This infant was observed for an additional 4 hours in the recovery room and did not have any further episodes of apnea. This same infant was brought to the emergency room 3 days following surgery for a
3 p!
16
II
14
= * r: .s h
12
6
6
8
4
No. of Patients
Prior ventilatory support
22
Apnea
11
Bradycardia
10
Bronchopulmonary dysplasia
9
Prior home apnea monior use
12
Asthma
4
Bronchitis
3
Pneumonia
8
Recent upper respiratory tract infection
4
presumed apneic episode. The infant was examined by the emergency room personnel, found to be normal, and discharged. Bradycardia to 80 beats/min was noted in one patient intraoperatively. This was transient and resolved quickly and spontaneously. Laryngospasm was observed in two patients following extubation in the operating room. One patient was briefly reintubated and subsequently extubated uneventfully in the recovery room. Laryngospasm in the other patient resolved spontaneously in the operating room. Two patients were noted to have respiratory difficulty following extubation in the operating room. One of these patients was reintubated in the operating room and subsequently extubated in the recovery room. A second patient was reintubated for possible aspiration following extubation. This infant was admitted for observation, uneventfully extubated 24 hours later, and discharged. This patient was the only one in the series of 124 patients who required postoperative hospitalization. Recovery Room Outcome
The average length of stay in the recovery room was 94 minutes (range, 30 to 240 minutes). One patient had a brief episode of bradycardia in the recovery room while sleeping. This was reversed by gentle stimulation and was without apparent sequelae. There were no other documented episodes of bradycardia noted in the charts for any of the remaining patients while in the recovery room. Table 3. Regimen Used for Anesthesia in 124 Infants Born
10
Prematurely Who Underwent
8
0
lnguinal Herniorrhaphy
AnestheticRegimen
$2 z’
lnguinal Herniorrhaphy
PastMedical History
3233343538373839404142434445404748485051525354555651 505D60 Postconceptional
Age (weeks)
Fig 1. Distribution of postconceptional ages (gestational age plus postnatal age) for 124 infants born prematurely who underwent inguinal herniorrhaphy.
No. of Patients
Nitrous oxide and fluothane
75
Nitrous oxide and forane
15
Nitrous oxidelfluothaneisuccinylcholine
11
Nitrous oxide/fluothane/forane
8
Fluothane
6
Nitrous oxide/forane/succinylcholine
4
Nitrous oxide/fluothane/atropine
3
Nitrous oxide/forane/succinyIcholine/atropine
2
OUTPATIENT
HERNIORRHAPHY IN PREMATURE INFANTS
Table 4. Postanesthesia-Related Herniorrhaphy
Problems Following lnguinal
in 8 Infants Born Prematurely NO.
Problem
of Patients
Outcome
Apnea
2
Resolved spontaneously.
Bradycardia
2
Resolved spontaneously.
Laryngospasm
2
Brief reintubation in 1 patient, the other patient resolved spontaneously.
Respiratory
2
difficulty
One patient was extubated in the recovery room. A second patient was reintubated, admitted for possible aspiration, and extubated 24 hours later.
Outcome Following Discharge One patient was noted to have a brief apneic episode at home several hours following discharge from the outpatient surgery center recovery room, which was relieved with gentle stimulation. This patient had a history of apnea, was on an apnea monitor prior to the surgery and remained on the apnea monitor following discharge from the surgery center. Thus, there were no patients who required hospitalization following discharge from the recovery room for any reason, including apnea or bradycardia. It is of note that with a 98% follow-up, only one patient had a documented episode of apnea within 24 hours of discharge from the outpatient surgery center recovery room. As noted previously, one patient was reintubated in the recovery room and hospitalized because of emesis and possible aspiration. No radiographic or clinical evidence of aspiration was noted and the patient was extubated successfully the following day and discharged. DISCUSSION An increasing percentage of extremely premature infants are able to survive because of marked improvements in neonatal care. One of the common sequela of prematurity is the development of an inguinal hernia.” Considerable debate has occurred regarding the appropriate timing and postoperative environment for inguinal herniorrhaphy in this unique group of patients.‘-5 Much of the concern has centered around the well-documented increased incidence of apnea associated with prematurity and following general anesthesia. In an article published in 1982, Steward’ noted that 12% of 33 infants born prematurely developed apnea up to 12 hours following general anesthesia. Two of these patients had had a prior history of apnea. Unfortunately, the specific time of the apnea episode following the completion of
205
anesthesia within this 1Zhour time frame was not identified for each patient. Apparently none of the patients with apnea required intubation. On the basis of his observations, Steward concluded that patients with a history of apnea, and particularly those under 46 weeks postconceptional age should be monitored for 24 hours postoperatively as an inpatient. In 1983 Liu et al2 evaluated 41 premature infants ( < 37 weeks gestation), 15 of whom had a preanesthetic history of apnea. Six of these 15 infants required prolonged ventilation following their operative procedure. Unfortunately, the length of ventilation or hospitalization was not stated. In addition, major surgical procedures were performed in 3 of the 6 patients who required prolonged ventilation. Thus, only 3 of 41 patients who were born premature and had inguinal herniorrhaphy required prolonged postanesthesia ventilation. Two of these patients were receiving theophylline for apnea preoperatively and the third patient received curare as one of the anesthetic agents, a medication known to increase the risk of postanesthesia apnea.’ On the basis of their experience Liu et al concluded that infants under 46 weeks postconceptional age and with a history of apnea, “should be admitted to the hospital postoperatively and closely monitored for 24 hours.“’ An editorial appearing in the same issue of AnesthesioZogy’ states that, “Based on the limited amount of information available, it is difficult to state with certainty that this is the correct conclusion.” However, these editorialists further state that unessential surgery for preterm infants less than 44 weeks postconceptional age should be delayed. When the operative procedure cannot be delayed, they recommended that the patients be hospitalized for postoperative observation for at least 18 hours. Rescorla and Grosfeld” reviewed their experience with inguinal herniorrhaphy in premature infants. Thirty infants were under 36 weeks gestational age. Two of the 30 premature infants required postoperative mechanical ventilation for apnea and bradycardia but the length of ventilation and hospitalization were not stated. On the basis of their experience they recommended that preterm infants requiring inguinal herniorrhaphy should be managed as inpatients and carefully observed postoperatively. Welborn et al’ evaluated 21 patients, (less than 37 weeks gestation at the time of birth) who subsequently underwent general anesthesia for inguinal herniorrhaphy. No episodes of apnea or bradycardia were identified. However, 8 patients developed “periodic breathing,” which they defined as apnea lasting 3 to 15 seconds separated by less than 20 seconds of normal breathing. Bradycardia was not associated with periodic breathing. All of these patients were less than 44 weeks
206
postconceptional age. None of their patients required prolonged intubation or mechanical ventilation. In a well-studied group of 47 preterm infants ( < 37 weeks gestation) who underwent general anesthesia before 60 postconceptional weeks, Kurth et al4 identified 18 patients who had prolonged (> 15 seconds) apnea following general anesthesia. Thirteen patients required only manual stimulation, and 4 patients had spontaneous recovery. Only one patient required reintubation for repeated prolonged apnea. Seventytwo percent of the patients had their initial apnea event within 2 hours of anesthesia. The authors concluded that “infants younger than 60 postconceptional weeks should be monitored continuously for at least 12 hours postoperatively.” In a 1987 report Mayhew et al5 evaluated 35 premature infants who underwent elective inguinal herniorrhaphy as inpatients. They noted that 4 patients required postoperative ventilation for apnea. Of note is that of the 7 infants who received pancuronium, 4 patients required postanesthesia ventilation. Unfortunately, the length of ventilation for these 4 patients was not stated in the publication. In reviewing the potential risk factors for postanesthetic apnea, the authors found that the best correlation was with a preoperative history of apnea or significant pulmonary disease. It is generally accepted that postanesthesia apnea is more likely to occur in infants born prematurely rather than at full term. On the basis of this observation and the articles cited above, it has been recommended that inpatient observation is necessary following general anesthesia for inguinal herniorrhaphy in infants born prematurely. However, on review of the information presented in these same publications, it is not clear that the data cited support the need for routine inpatient observation beyond the recovery room. The timing of the apnea episodes were not well defined in the patients cited in these articles. However, it would appear, based on available information contained in the articles, that the apnea episodes and other significant respiratory events occurred very soon after extubation, or that it was elected not to extubate the infant immediately following cessation of anesthesia because of documented apnea. The nondepolarizing muscle relaxant pancuronium was used in several of the patients cited in the literature that required prolonged intubation. It was pointed out both by Liu et al2 and Mayhew et al5 that pancuronium seemed to lead to a higher incidence of postanesthesia respiratory complications. The incidence of apnea was remarkably low in the present patient series. The basis for this is not entirely clear. However, pancuronium was not used, and the muscle
MELONE ET AL
relaxant succinylcholine was used in only 17 patients (of a total of 124 patients). In addition, preoperative and intraoperative narcotics were not used. It is important to note that the low incidence of apnea was in spite of the fact that 67 of the patients were less than 46 weeks postconceptional age, 28 of the patients were less than 41 weeks postconceptional age, and 11 patients had a previous history of apnea. It would seem logical to accept the recommendation that premature infants requiring inguinal herniorrhaphy be observed as inpatients postoperatively. However, one has to ask what benefits would be derived from inpatient observation in those infants that are extubated shortly after the completion of the operative procedure and appear to be doing well 1 to 2 hours later. Certainly, close observation by trained personnel using monitoring equipment can be advantageous. However, monitoring equipment such as apnea monitors are available for home use. These monitors were frequently used in our patient series. Although it may appear that trained personnel are necessary for postanesthesia observation, it has been our experience that those infants likely to require those skills (such as intubation) declare themselves early following surgery and anesthesia. In the majority of infants postanesthesia with delayed-onset apnea, stimulation alone is all that is necessary. In addition, hospital personnel are likely to lack familiarity with each patient’s breathing patterns, etc. In contrast, a reliable parent is familiar with his/her infant’s normal respiratory pattern and may well have had prior experience with apnea. We found that many of the families were familiar with apnea monitors because their infants were placed on them following hospital discharge. Perhaps the most relevant fact is that in our review of the literature we were not able to identify any patients that required intubation beyond two to three hours postanesthesia. In our own patient series none of the infants required admission to a hospital once they had been discharged from the outpatient recovery room. Finally, hospitalization is not without its own risks and one can not ignore the expense incurred with routine inpatient care following inguinal herniorrhaphy in this patient population. We believe that outpatient herniorrhaphy under general anesthesia can be a safe treatment plan for infants that are born prematurely. We base this conclusion primarily on our own experience, but also because of a lack of objective data in the literature to support the recommendation that 24-hour inpatient observation following general anesthesia for inguinal herniorrhaphy should be mandatory in infants born prematurely. However, we do not mean to imply that
OUTPATIENT
HERNIORRHAPHY
IN PREMATURE
207
INFANTS
all infants born prematurely will be candidates for outpatient herniorrhaphy, or that all outpatient surgical facilities should embrace this approach.
ACKNOWLEDGMENT The authors thank Ben Antonio and John Bringas for their assistance in data collection.
REFERENCES 1. Steward DJ: Preterm infants are more prone to complications following minor surgery than are term infants. Anesthesiology 56:304-306, 1982 2. Liu LMP, Cote CJ, Goudsouzian NG, et al: Life threatening apnea in infants recovering from anesthesia. Anesthesiology 59:506510,1983 3. Rescorla FJ. Grosfeld JL: Inguinal hernia repair in the perinatal period and early infancy: Clinical considerations. J Pediatr Surg 19:832-837. 1984 4. Kurth CD, Spitzer AR, Broennle AM, et al: Postoperative apnea in preterm infants. Anesthesiology 66:483-488, 1987
5. Mayhew JF, Bourke DL, Guinee WS: Evaluation of the premature infant at risk for postoperative complications. Can J Anaesth 34:627-631, 1987 6. Harper RG. Garcia A, Sia C: Inguinal hernia: A common problem of premature infants weighing 1000 gms or less at birth. Pediatrics 56:112-115, 1975 7. Gregory GA, Steward DJ: Life-threatening perioperative apnea in the ex-“premie.” Anesthesiology 59:495-498. 1983 8. Welborn LG, Ramirez N, Oh TH. et al: Evaluation of anesthetic risks in premature infants. Anesthesiology 61:A417. 1984 (abstr)
Discussion D.A. Cuniano (Columbus, OH): Since premature infants comprise upwards of 10% of patients requiring inguinal herniorrhaphy, their admission status certainly has clinical relevance to all of us in this room. In Columbus, we have also been concerned about this group of patients and we recently embarked on a perspective study which was conducted by Dr Daniel Teitelbaum, our pediatric surgical trainee. He collaborated with the members of our Anesthesiology Department and over a l-year period, they prospectively evaluated 40 full-term infants and 62 preterm infants with a postconceptual age of less than 60 weeks. They evaluated all patients with no selection criteria other than age. The infants were monitored continuously by pulse oximetry as well as a pneumocardiogram. The monitoring occurred in the recovery room, postrecovery room, and in the patient’s room for those infants who required hospitalization. Unfortunately, the preterm infants in Columbus, OH, do much more poorly than the infants in California. In our study, the authors concluded that two major problems occurred in the preterm infant. In the recovery room, there was a 28% incidence of significant apnea and bradycardia, which required vigorous stimulation in order to be relieved. More importantly, 20% of the preterm infants had a significant apneic event up to 4 to 10 hours following their operation. So this was well beyond the period of their discharge from the recovery room setting and all of these events occurred in the patient’s room. I have basically three questions for the authors. The discrepancy between the results in Columbus and the results you have given us today might be explained by a couple of factors. First of all, since you used a
retrospective analysis, could there have been some hidden prior selection criteria so that less healthy or vigorous preterm infants were excluded from being outpatients? Second, the infants in your study were monitored in the recovery room by vital signs and heart rate. Since pulse oximetry and pneumocardiograms were not used, could you have missed episodes of oxygen desaturation, apnea, or bradycardia because you did not employ these monitors? Third, your patients remained in the recovery room for up to 4 hours following operation, long enough to be given oral fluids. Is this routine practice in your hospital, since most of the major teaching centers are not staffed adequately in order to keep patients in the recovery room setting for this length of time? In conclusion, of most concern, I think, is your general recommendation that all preterm infants can be safely handled as outpatients. It would seem that several caveats need to be in place. First, a highly experienced group of anesthesiologists; second, acceptance of potential medicolegal liability because even one cardiorespiratory catastrophe could be disastrous in this patient population; and third, a unique outpatient facility would be necessary in order to achieve your excellent results. A. Browne (Portland, ME): I’m certainly glad you have brought this subject to our attention and I applaud your results. However, I think you need to explain to us how you did it. What did you do differently from all of the other anesthesiologists and surgeons in North America? Is there a difference in your anesthesia technique? If people are going to read this and say “I can go to the local surgicenter and have my hernia fixed,” we have to have a technique
208
that we can tell the surgicenter personnel about and you haven’t really pointed out what was the difference in what you did. K. Georgeson (Birmingham, AL): How long did the infants stay in their room before discharge? M. Gauderer (Cleveland, OH): I have one comment and one question. The comment is that prematurity is really a spectrum. We are seeing an increase in extremely low birth weight infants, children with a birth weight under 1,500 g are surviving. So I think it is very important to define the type of premature that we are really talking about. The question is what was the operating room time? The authors defined operating time but not the time in the operating room. I think that that can be markedly increased by operating on prematures. J. Langer (Hamilton, Ontario): Since both pain and pain control agents may affect the incidence of apnea in premature babies, I wonder if you could comment on what kind of analgesia was used in your series? J.C. German (Orange County, CA): Diller Groff reported about 10 years ago that these premature infants, as well as other infants with high-risk criteria, have longer operating and recovery room times. And, all of us know who assist residents in doing the tiny prematures that it just does take a longer time. Also these infants in our own experience tend to declare themselves on emergence from anesthesia in that they develop periodic breathing and they take a long time to extubate so that operating room time itself is really a lot longer in our experience. So this has to be looked at and it sounds like everybody is trying to look at the same thing. R. Pearl (Washington, D.C.): Which patients were excluded from this study? J. Melone (response): Dr Caniano, regarding the issue that you raised as did Dr Pearl, there was no selection process once the infants were discharged from the neonatal unit. Therefore, this is an inclusive rather than exclusive series. Your second question referred to possible missed episodes of oxygen desaturation. It is possible that very brief desaturation
MELONE ET AL
episodes may have occurred. However, they did not appear to be clinically significant either in the recovery room where the patients were monitored for apnea and bradycardia or at home. Regarding the question of oral fluids postoperatively, all of the infants were given oral fluids usually within 30 minutes of arrival in the recovery room. Finally, you asked if it is safe to treat all infants born prematurely that require inguinal herniorrhaphy in an outpatient unit. We would suggest that this be determined by individual judgement based on your assessment of the patient’s risk and the outpatient environment available to you. On the basis of our experience in our setting it was safe. Dr Brown asked what did we do differently regarding the anesthetic technique? The cause for our low incidence of postanesthesia apnea is not clear. However, attending anesthesiologists performed the anesthesia and they did not use narcotics preoperatively or intraoperatively. Also, in only 14% of infants did they use muscle relaxants. We are not sure if these factors led to our lower incidence of apnea and bradycardia. Previous publications have suggested that muscle relaxants, especially pancuronium, increase the risk of apnea. Dr Jorgesen, all infants were discharged directly home from the recovery room. Regarding your question on how we convinced our anesthesiologists: The outpatient facility that was used was one of the first free-standing units to be opened in the mid-1970s. Several of the anesthesiologists, already being pioneers, were willing to take on a new challenge. We had observed that inpatient herniorrhaphy in this group of patients did not seem necessary and suggested that we do them as outpatients. They agreed. Dr Gauderer, the operating room time as we reported it included the time from induction to completion of anesthesia. Dr Langer, Tylenol was used for pain control. Dr Hatch, we have done well with our approach and, therefore, have not felt a need to try other alternatives.
