I 102
Correspondence
At follow-up the child was well. The fits were not due to severe head injury, and the unrousable state was apparently postictal. The potential consequences in a child with a severe head injury and developing cerebral oedema could have been disastrous. If a condenser humidifier must be
added it should be appropriate for the size of the child and without the catheter mount. St. James University Hospital. Leeds LS9 7TF
L.M. Fox
The human wedge
I read with interest the article ‘The human wedge’, describing an important manoeuvre tp relieve aortocaval compression during resuscitation in late pregnancy (Anaesthesia 1992; 47: 433-4). I found it unusual that the picture presented would depict the supine patient wedged with the right side downward for a number of reasons. Clinically, I have always moved the uterus to the left in order to avoid caval occlusion, while recognising that this may predispose to pressure on the aorta. This may reduce uterine blood flow (and fetal oxygenation) but would tend to augmentation of maternal blood pressure, cardiac filling and peripheral resistance, all desirable during maternal resuscitation. The aorta may be more resistant to compression than the inferior vena cava due to higher intravascular pressure (when present) and to the intrinsic fibromuscular structure of the vessel itself. During resuscitation, the return of maternal haemodynamics is paramount and I would argue that wedging to the right may still allow some caval compression. The authors suggested that chest compression was ‘better’ under wedged conditions, because the incidence of correct compressions was 66.6% vs 32.5% when delivered strictly supine. The most common cause of incorrect
compression was reportedly due to excessive force. I would ask if it is possible that these differences in ‘correctness’ may be systematic errors in the study design. Perhaps the real message is that compression force is inherently less in the wedged position. This question needs to be answered and the proper techniques systematically taught. Basic life support training courses routinely teach techniques of infant, child and adult management. It is time to incorporate the specific technique of life support of the fourth ‘type’ of human, the term pregnant female, into all training programmes. Riverside Hospital, Toledo, Ohio 43604, USA
P.M. KEMPEN
The Editor replies The author of the human wedge amended his paper at the proof stage to indicate that the left lateral was the preferred position. However, because of an oversight this information was not included in the final version.
Capnography and broncho-oesophageal fistula
We report a patient in whom the use of a capnograph enabled a diagnosis of broncho-oesophageal fistula to be made during the course of a rigid oesophagoscopy under general anaesthesia. A 55-year-old woman with carcinoma of the oesophagus was scheduled to undergo rigid oesophagoscopy and oesophageal dilatation under general anaesthesia. After preoxygenation, anaesthesia was induced using a rapid sequence technique with cricoid pressure. Induction was with propofol and suxamethonium and maintenance with nitrous oxide, enflurane and vecuronium. Orotracheal intubation was performed using a 7.5 rnm I.D. ‘south facing’ tracheal tube and capnography was commenced using a Datex Normocap capnograph (Datex Division Instrumentarium Corp., Helsinki, Finland). At oesophagoscopy an encircling stricture was seen at the level of 18 cm from the lips. The surgeon (G.J.) commented that he could see bubbles formed by gas emerging via the lumen of the oesophagus from below the stricture. The origin of this gas was discussed. If this was coming from the stomach the intention was to go ahead with dilatation of the stricture, if from a broncho-oesophageal fistula, then oesophageal dilatation would be contra-indicated. The sampling tube from the capnograph was passed down the lumen of the rigid oesophagoscope and the capnograph showed the presence of CO, in the gas emerging from the lumen of the stricture. This, however,
was not diagnostic, as it is well known that gastric gas contains COz. To further investigate this situation, the inspired gases were altered to contain 8% CO, for a few breaths. Within two breaths, there was a marked change in the readings displayed by the capnograph; instead of cycling between 0% and 5% it was now cycling between 8% and approximately 6%, and these changes were reversed when the COz was stopped. It was thus possible to say with confidence that there was a broncho-oesophageal stricture and the investigation was terminated at this point, with no dilatation being performed. The rest of the anaesthetic, and recovery were unremarkable. We believe that this is the first time that the pre-operative diagnosis of a broncho-oesophageal fistula with a capnograph has been reported. The advantage of added safety with capnography during general anaesthesia can be augmented by using it to trace the path of respiratory gases in patients with abnormal anatomy. It is worthy of notc that this is only possible using an anaesthetic machine with which the use of C 0 2 is still permitted. In the absence of this, one might consider using a volatile agent meter to perform a similar function, although in this case there was not one available. Singleton Hospitrtl. Swansea
Capnography and awareness
We wish to report two cases in which problems were caused during general anaesthesia by inadvertent depression of the emergency oxygen flush button. Both cases involved emergency Caesarean section and in both instances a pre-
anaesthetic check of the Boyles International machine found everything to be in order, including the oxygen flush button which correctly delivered high flow oxygen. In the first case anaesthesia was induced with a rapid
Correspondence
At follow-up the child was well. The fits were not due to severe head injury, and the unrousable state was apparently postictal. The potential consequences in a child with a severe head injury and developing cerebral oedema could have been disastrous. If a condenser humidifier must be
added it should be appropriate for the size of the child and without the catheter mount. St. James University Hospital. Leeds LS9 7TF
L.M. Fox
The human wedge
I read with interest the article ‘The human wedge’, describing an important manoeuvre tp relieve aortocaval compression during resuscitation in late pregnancy (Anaesthesia 1992; 47: 433-4). I found it unusual that the picture presented would depict the supine patient wedged with the right side downward for a number of reasons. Clinically, I have always moved the uterus to the left in order to avoid caval occlusion, while recognising that this may predispose to pressure on the aorta. This may reduce uterine blood flow (and fetal oxygenation) but would tend to augmentation of maternal blood pressure, cardiac filling and peripheral resistance, all desirable during maternal resuscitation. The aorta may be more resistant to compression than the inferior vena cava due to higher intravascular pressure (when present) and to the intrinsic fibromuscular structure of the vessel itself. During resuscitation, the return of maternal haemodynamics is paramount and I would argue that wedging to the right may still allow some caval compression. The authors suggested that chest compression was ‘better’ under wedged conditions, because the incidence of correct compressions was 66.6% vs 32.5% when delivered strictly supine. The most common cause of incorrect
compression was reportedly due to excessive force. I would ask if it is possible that these differences in ‘correctness’ may be systematic errors in the study design. Perhaps the real message is that compression force is inherently less in the wedged position. This question needs to be answered and the proper techniques systematically taught. Basic life support training courses routinely teach techniques of infant, child and adult management. It is time to incorporate the specific technique of life support of the fourth ‘type’ of human, the term pregnant female, into all training programmes. Riverside Hospital, Toledo, Ohio 43604, USA
P.M. KEMPEN
The Editor replies The author of the human wedge amended his paper at the proof stage to indicate that the left lateral was the preferred position. However, because of an oversight this information was not included in the final version.
Capnography and broncho-oesophageal fistula
We report a patient in whom the use of a capnograph enabled a diagnosis of broncho-oesophageal fistula to be made during the course of a rigid oesophagoscopy under general anaesthesia. A 55-year-old woman with carcinoma of the oesophagus was scheduled to undergo rigid oesophagoscopy and oesophageal dilatation under general anaesthesia. After preoxygenation, anaesthesia was induced using a rapid sequence technique with cricoid pressure. Induction was with propofol and suxamethonium and maintenance with nitrous oxide, enflurane and vecuronium. Orotracheal intubation was performed using a 7.5 rnm I.D. ‘south facing’ tracheal tube and capnography was commenced using a Datex Normocap capnograph (Datex Division Instrumentarium Corp., Helsinki, Finland). At oesophagoscopy an encircling stricture was seen at the level of 18 cm from the lips. The surgeon (G.J.) commented that he could see bubbles formed by gas emerging via the lumen of the oesophagus from below the stricture. The origin of this gas was discussed. If this was coming from the stomach the intention was to go ahead with dilatation of the stricture, if from a broncho-oesophageal fistula, then oesophageal dilatation would be contra-indicated. The sampling tube from the capnograph was passed down the lumen of the rigid oesophagoscope and the capnograph showed the presence of CO, in the gas emerging from the lumen of the stricture. This, however,
was not diagnostic, as it is well known that gastric gas contains COz. To further investigate this situation, the inspired gases were altered to contain 8% CO, for a few breaths. Within two breaths, there was a marked change in the readings displayed by the capnograph; instead of cycling between 0% and 5% it was now cycling between 8% and approximately 6%, and these changes were reversed when the COz was stopped. It was thus possible to say with confidence that there was a broncho-oesophageal stricture and the investigation was terminated at this point, with no dilatation being performed. The rest of the anaesthetic, and recovery were unremarkable. We believe that this is the first time that the pre-operative diagnosis of a broncho-oesophageal fistula with a capnograph has been reported. The advantage of added safety with capnography during general anaesthesia can be augmented by using it to trace the path of respiratory gases in patients with abnormal anatomy. It is worthy of notc that this is only possible using an anaesthetic machine with which the use of C 0 2 is still permitted. In the absence of this, one might consider using a volatile agent meter to perform a similar function, although in this case there was not one available. Singleton Hospitrtl. Swansea
Capnography and awareness
We wish to report two cases in which problems were caused during general anaesthesia by inadvertent depression of the emergency oxygen flush button. Both cases involved emergency Caesarean section and in both instances a pre-
anaesthetic check of the Boyles International machine found everything to be in order, including the oxygen flush button which correctly delivered high flow oxygen. In the first case anaesthesia was induced with a rapid
