Correspondence and in detailed written instructions presented with the kit, is that having obtained vascular access with the 18 gauge needle, the Arrow safety syringe is left attached to the needle and the guidewire passed down the central lumen of the syringe and needle; the syringe and needle are then removed as a unit. This technique has the potential to allow inadvertent arterial puncture to remain unrecognised until after the vessel has been dilated and the multilumen catheter introduced. Alternative techniques to aid recognition of inadvertent arterial cannulation include: ( I ) removal of the syringe from the needle to observe the flow and colour of the blood from the needle hub; (2) transduction of vascular pressure directly from the needle, which also requires removal of the syringe from the needle; (3) blood gas analysis of the aspirate. There are other factors which I believe contribute to the loss of discriminatory sensitivity during venepuncture and passage of the guidewire. The syringe plunger moves with a hesitant and sticking movement within the barrel, due to resistance of the plunger on the metal central lumen of the syringe. No clear idea of the pressure within or of the force required to aspirate blood to the syringe is obtained. In passing down the central lumen of the syringe, the guidewire passes through a valve designed to prevent air leaking down the lumen into the patient and to prevent leakage of blood in the opposite direction. This valve presents a resistance to the passage of the guidewire with subsequent loss of feel for increased resistance due for example to misplacement of the wire. For these reasons I consider that the Arrow safety syringe is a misnomer and recommend that it not be used routinely for detection of a vessel or for passage of the guide wire. Launceston General Hospital. Launceston, Tasmania, Australia
S. FRASER
directly through the syringe without disconnecting it from the needle. Prior to the invention of the Raulerson syringe by D r Dan Raulerson, the syringe had to be disconnected from the introducer needle before advancing a guidewire through the needle into the vessel during attempted cannulation. Thus, three potential problems were addressed: ( I ) loss of vessel access may result during the process of disconnecting the syringe from the needle, since the needle tip tends to move; (2) the risk of air embolisation during spring-wire introduction is reduced, since the needle is not open to the atmosphere; (3) the blood is better contained. The Arrow Raulerson syringe not only allows for the capability of passing a spring-wire guide, it does function as a standard, ordinary syringe. Thus, during vessel cannulation, the Raulerson syringe can be used to aspirate blood and then detached from the needle so the guidewire can be passed, as is traditional practice. Our current instructions indicate the importance of not relying on the colour of the blood as an accurate indicator of the vessel cannulated. In addition, each Raulerson syringe kit includes a transduction probe (20 G x 3.5 inch blunt needle) for insertion into the syringe plunger. The transduction probe interrupts the valves in the syringe plunger and allows the pressure from the vessel cannulated to be transduced without disconnecting the syringe from the needle. Pressure waveform transduction has been shown to be a reliable indicator o f venous cannulation [l]. Finally, the loss of feel described by D r Fraser is one of physician preference and perception. This is certainly not a universal statement and again, if desired, the Raulerson syringe can be detached from the needle and the guidewire inserted in the usual fashion. The advantages of the Raulerson syringe, coupled with the use of the transduction probe, offers many physicians a n important enhancement to successful vessel cannulation. Arrow International, Reading, Pennsylvania 19610, USA
A reply
Dr Fraser’s points are well taken, but it is important to recognise that the Arrow Raulerson syringe offers the optional feature of allowing the guidewire to be passed
215
P.J. MCGREGOR
Reference [I] JOB= DR, SCWARTZ AJ, GREENHOW DE, STEPHENSON LW, ELLISONN. Safer jugular vein cannulation recognition of arterial puncture and preferential use of the external jugular route. Anesthesiology October 1983; 353-5.
Supplementary oxygen causing surgical emphysema Further to the editorial ‘Supplementary oxygen potential for disaster’ (Anaesthesia 1991; 46: 905-6) we report a problem we encountered recently following the use of supplementary oxygen. A 12-year-old girl with Down’s syndrome underwent posterior spinal fusion to correct her scoliosis; the operation and anaesthetic were uneventful. At operation a right subclavian central line was inserted. A postoperative chest X ray showed n o pneumothorax. Postoperatively she was extremely restless despite adequate pain relief with an intravenous morphine infusion. She required oxygen therapy, without which her oxygen saturation fell to 84%. She was unable to tolerate oxygen via a facemask and we were unable to use nasal cannulae as she had a 12 FG nasogastric tube in her left nostril. It was decided to provide supplementary oxygen via a 6 FG suction catheter placed in her right nostril to a depth of 3 cm and secured at this distance by sticking the catheter to her cheek with
adhesive tape. Oxygen was delivered a t a flow of 0.5 I.min-I. Recovery was uneventful until 60 h postoperatively when it was noted that she had developed marked swelling of the right side of her face and neck extending from just above the clavicle to above the orbit. O n clinical examination this was found to be surgical emphysema. It was significant that she had removed her central line several hours earlier. An occlusive dressing had been placed over the exit site. No emphysema was seen below the right clavicle. Fortunately at no time was her airway compromised. It was suspected that oxygen via the nasal catheter might have been the cause of the surgical emphysema. The catheter was therefore removed, but with some difficulty, as it seemed adherent to the nasal mucosa. A chest X ray was repeated and again showed no pneumothorax. The surgical emphysema gradually reduced over the following 3 days, but was noted to fluctuate with nose blowing.
We pesume that a small mucosal tear deither with insertion or movement of the nasal catheter and that continual oxygen flow caused the surgical emphysema. Surgical emphysema of this origin could well compromise the airway and is another potentially serious complication of oxygen therapy delivered by this route.
lbe -’fle Although the aims of prwedication may be disputed, whether they be anxiolytk, amnesic,sedative or ‘narcotic’, or indeed whether premeditation is necessary at all, a large body of clinical opinion recognises a ‘well-premedicated‘ patient The possibility of repeated anaesthesia really necessitates that the ‘&ectiveness’ of premedication be recorded objectively. The following Scoring system has been elabor-
Queen Mary’s Hospital for Children, Carshalton, SurreySM54NR
P. NEWMAN
P. RADFORD B.J. EPPEL
of premedcation ated over the years and has been found to be most useful: 0, no effect; I , subjective effect only; 2, subjective and objective effect but awake; 3, sleeping but responds to normal conversation; 4, not responsive to normal conversation. The Royal Surrey County Hospital, Guildford GU2 5 X X
J.M. LEIGH
Smbmtmmm opioids: the painles approach
Dr Teillol-Foo’s observations on the use of an indwelling intramuscular cannula for postoperative analgesia (Anaesthesia 1991; 46c 897) are interesting and should certainly be consided before committing patients to repeated intramuscular injections. If one of the aims of the anaesthetist is to relieve pain, we should not accept that the barbaric idlidion of a 20 gauge needle (or 21 gauge as we would use) is justified by its end result. In central Nottinghamshire we have recently introduced an acute pain service and, as in many other centres, we make wide use of patient controlled analgesia, but as we have a paucity of equipment we run a subcutaneous regimen alongside. This involves an indwelling cannula, usually a 20 gauge Venflon, which is sited subcutaneously during anaesthesia, either on the chest wall or the anterior thigh (especially ifa regional block has been used). Nurses are requested to give a variable dose of opioid (usually morphine) according to a rigid protocol. The success of this method depends upon the enthusiasm of the nurses, who willingly assess patients’ pain hourly and give appropriate quantities of drug, despite some difficulties with the Controlled Drug Register. Motivation is enhanced by their observing a great improvement in postoperative pain relief. All risk of &stick injury at the patient site is avoided as the injection is given via the V e d o n port; the small ‘deadspace’ is usually only relevant at the first administration and, as this dose is usually the largest, say 1 ml, this should not be significant. Nurses are instructed not to dilute drugs not to flush the cannulae. It has been shown that absorption from both subcuta-
neous and intramuscular sites follows a similar time course and that the absorption profile in a particular patient is more reproducible via the same subcutaneous site than via several different intramuscular ones. The actual injection may not be entirely painless and some patients do describe a mild irritation at the cannula tip, although all questioned would agree that the regimen is far superior to the intramuscular method. Unfortunately, we have not found that the regimen produces any significant reduction in nausea and vomiting and, as antiemetics cause a local skin reaction when given subcutaneously, such injections cannot be combined with the opioid, except perhaps when using low dose droperidol. It may, of course, be necessary to administer an occasional bolus dose of opioid to a patient who does not have an indwelling cannula. We believe that such injections could also be prescribed subcutaneously and, therefore, we can see no further role for intramuscular opioids, unless they are to be combined with an antiemetic. We freely admit that we are not the first to advocate subcutaneous injections of opioids and perhaps not the first to suggest the use of an indwelling cannula, but, from our recent experience we would confidently recommend this technique be used more widely, even by our more sceptical immediate colleagues. Comparison of this regimen with that of Dr Teillol-Foo would be worthwhile. ManSJield Hospitals, Nottinghamshire
P.T. BULL M.J. MOWBRAY S.J. MARKHAM
Burns due to pulse oximetry
A 4-month-old baby, whose lungs were ventilated for 14 days for ventilatory failure secondary to bronchiolitis, suffered burns to his big toe related to the site of application of a pulse oximeter probe (Fig. I). The probe involved was a Nellcor N25 oxisensor and was combined with a Hewlett Packard HP Model 66s monitor and module. Prior to the discovery of the bum, the patient had no periods of poor peripheral perfusion and there had been no problems with the pulse oximeter trace. On the 13th day he was noted to have blistering beneath the pulse oximeter probe on two-thirds of the circumference of his left big toe, and a similar but smaller lesion on the right big toe. These
had not been present during examination earlier in the day and had not been noticed during routine rotation of the position of the probe. This consists of movement of the probe to another limb every 3 h and is standard practice for the nurses on the intensive care unit. The pulse oximeter probe was removed and the light source felt to be hotter than usual. The lesions have been managed conservatively and are resolving satisfactorily. The pulse oximeter probe was returned to the manufacturer for assessment. Following this episode, the heat production from a number of similar probes was tested. Six pulse oximeter probes were suspended in a Drager 8000 incubator main-
S. FRASER
directly through the syringe without disconnecting it from the needle. Prior to the invention of the Raulerson syringe by D r Dan Raulerson, the syringe had to be disconnected from the introducer needle before advancing a guidewire through the needle into the vessel during attempted cannulation. Thus, three potential problems were addressed: ( I ) loss of vessel access may result during the process of disconnecting the syringe from the needle, since the needle tip tends to move; (2) the risk of air embolisation during spring-wire introduction is reduced, since the needle is not open to the atmosphere; (3) the blood is better contained. The Arrow Raulerson syringe not only allows for the capability of passing a spring-wire guide, it does function as a standard, ordinary syringe. Thus, during vessel cannulation, the Raulerson syringe can be used to aspirate blood and then detached from the needle so the guidewire can be passed, as is traditional practice. Our current instructions indicate the importance of not relying on the colour of the blood as an accurate indicator of the vessel cannulated. In addition, each Raulerson syringe kit includes a transduction probe (20 G x 3.5 inch blunt needle) for insertion into the syringe plunger. The transduction probe interrupts the valves in the syringe plunger and allows the pressure from the vessel cannulated to be transduced without disconnecting the syringe from the needle. Pressure waveform transduction has been shown to be a reliable indicator o f venous cannulation [l]. Finally, the loss of feel described by D r Fraser is one of physician preference and perception. This is certainly not a universal statement and again, if desired, the Raulerson syringe can be detached from the needle and the guidewire inserted in the usual fashion. The advantages of the Raulerson syringe, coupled with the use of the transduction probe, offers many physicians a n important enhancement to successful vessel cannulation. Arrow International, Reading, Pennsylvania 19610, USA
A reply
Dr Fraser’s points are well taken, but it is important to recognise that the Arrow Raulerson syringe offers the optional feature of allowing the guidewire to be passed
215
P.J. MCGREGOR
Reference [I] JOB= DR, SCWARTZ AJ, GREENHOW DE, STEPHENSON LW, ELLISONN. Safer jugular vein cannulation recognition of arterial puncture and preferential use of the external jugular route. Anesthesiology October 1983; 353-5.
Supplementary oxygen causing surgical emphysema Further to the editorial ‘Supplementary oxygen potential for disaster’ (Anaesthesia 1991; 46: 905-6) we report a problem we encountered recently following the use of supplementary oxygen. A 12-year-old girl with Down’s syndrome underwent posterior spinal fusion to correct her scoliosis; the operation and anaesthetic were uneventful. At operation a right subclavian central line was inserted. A postoperative chest X ray showed n o pneumothorax. Postoperatively she was extremely restless despite adequate pain relief with an intravenous morphine infusion. She required oxygen therapy, without which her oxygen saturation fell to 84%. She was unable to tolerate oxygen via a facemask and we were unable to use nasal cannulae as she had a 12 FG nasogastric tube in her left nostril. It was decided to provide supplementary oxygen via a 6 FG suction catheter placed in her right nostril to a depth of 3 cm and secured at this distance by sticking the catheter to her cheek with
adhesive tape. Oxygen was delivered a t a flow of 0.5 I.min-I. Recovery was uneventful until 60 h postoperatively when it was noted that she had developed marked swelling of the right side of her face and neck extending from just above the clavicle to above the orbit. O n clinical examination this was found to be surgical emphysema. It was significant that she had removed her central line several hours earlier. An occlusive dressing had been placed over the exit site. No emphysema was seen below the right clavicle. Fortunately at no time was her airway compromised. It was suspected that oxygen via the nasal catheter might have been the cause of the surgical emphysema. The catheter was therefore removed, but with some difficulty, as it seemed adherent to the nasal mucosa. A chest X ray was repeated and again showed no pneumothorax. The surgical emphysema gradually reduced over the following 3 days, but was noted to fluctuate with nose blowing.
We pesume that a small mucosal tear deither with insertion or movement of the nasal catheter and that continual oxygen flow caused the surgical emphysema. Surgical emphysema of this origin could well compromise the airway and is another potentially serious complication of oxygen therapy delivered by this route.
lbe -’fle Although the aims of prwedication may be disputed, whether they be anxiolytk, amnesic,sedative or ‘narcotic’, or indeed whether premeditation is necessary at all, a large body of clinical opinion recognises a ‘well-premedicated‘ patient The possibility of repeated anaesthesia really necessitates that the ‘&ectiveness’ of premedication be recorded objectively. The following Scoring system has been elabor-
Queen Mary’s Hospital for Children, Carshalton, SurreySM54NR
P. NEWMAN
P. RADFORD B.J. EPPEL
of premedcation ated over the years and has been found to be most useful: 0, no effect; I , subjective effect only; 2, subjective and objective effect but awake; 3, sleeping but responds to normal conversation; 4, not responsive to normal conversation. The Royal Surrey County Hospital, Guildford GU2 5 X X
J.M. LEIGH
Smbmtmmm opioids: the painles approach
Dr Teillol-Foo’s observations on the use of an indwelling intramuscular cannula for postoperative analgesia (Anaesthesia 1991; 46c 897) are interesting and should certainly be consided before committing patients to repeated intramuscular injections. If one of the aims of the anaesthetist is to relieve pain, we should not accept that the barbaric idlidion of a 20 gauge needle (or 21 gauge as we would use) is justified by its end result. In central Nottinghamshire we have recently introduced an acute pain service and, as in many other centres, we make wide use of patient controlled analgesia, but as we have a paucity of equipment we run a subcutaneous regimen alongside. This involves an indwelling cannula, usually a 20 gauge Venflon, which is sited subcutaneously during anaesthesia, either on the chest wall or the anterior thigh (especially ifa regional block has been used). Nurses are requested to give a variable dose of opioid (usually morphine) according to a rigid protocol. The success of this method depends upon the enthusiasm of the nurses, who willingly assess patients’ pain hourly and give appropriate quantities of drug, despite some difficulties with the Controlled Drug Register. Motivation is enhanced by their observing a great improvement in postoperative pain relief. All risk of &stick injury at the patient site is avoided as the injection is given via the V e d o n port; the small ‘deadspace’ is usually only relevant at the first administration and, as this dose is usually the largest, say 1 ml, this should not be significant. Nurses are instructed not to dilute drugs not to flush the cannulae. It has been shown that absorption from both subcuta-
neous and intramuscular sites follows a similar time course and that the absorption profile in a particular patient is more reproducible via the same subcutaneous site than via several different intramuscular ones. The actual injection may not be entirely painless and some patients do describe a mild irritation at the cannula tip, although all questioned would agree that the regimen is far superior to the intramuscular method. Unfortunately, we have not found that the regimen produces any significant reduction in nausea and vomiting and, as antiemetics cause a local skin reaction when given subcutaneously, such injections cannot be combined with the opioid, except perhaps when using low dose droperidol. It may, of course, be necessary to administer an occasional bolus dose of opioid to a patient who does not have an indwelling cannula. We believe that such injections could also be prescribed subcutaneously and, therefore, we can see no further role for intramuscular opioids, unless they are to be combined with an antiemetic. We freely admit that we are not the first to advocate subcutaneous injections of opioids and perhaps not the first to suggest the use of an indwelling cannula, but, from our recent experience we would confidently recommend this technique be used more widely, even by our more sceptical immediate colleagues. Comparison of this regimen with that of Dr Teillol-Foo would be worthwhile. ManSJield Hospitals, Nottinghamshire
P.T. BULL M.J. MOWBRAY S.J. MARKHAM
Burns due to pulse oximetry
A 4-month-old baby, whose lungs were ventilated for 14 days for ventilatory failure secondary to bronchiolitis, suffered burns to his big toe related to the site of application of a pulse oximeter probe (Fig. I). The probe involved was a Nellcor N25 oxisensor and was combined with a Hewlett Packard HP Model 66s monitor and module. Prior to the discovery of the bum, the patient had no periods of poor peripheral perfusion and there had been no problems with the pulse oximeter trace. On the 13th day he was noted to have blistering beneath the pulse oximeter probe on two-thirds of the circumference of his left big toe, and a similar but smaller lesion on the right big toe. These
had not been present during examination earlier in the day and had not been noticed during routine rotation of the position of the probe. This consists of movement of the probe to another limb every 3 h and is standard practice for the nurses on the intensive care unit. The pulse oximeter probe was removed and the light source felt to be hotter than usual. The lesions have been managed conservatively and are resolving satisfactorily. The pulse oximeter probe was returned to the manufacturer for assessment. Following this episode, the heat production from a number of similar probes was tested. Six pulse oximeter probes were suspended in a Drager 8000 incubator main-
