Correspondence oedema had resolved. Omeprazole [3] might be a suitable alternative to ranitidine if this patient required another Caesarean section in the future. We have reported the case to the Committee on Safety of Medicines and the drug manufacturers. It would be interesting to know of any other similar cases.
Guy's Hospital, London SEI 9RT
J.E.S. BARRY R. MADAN P.B. HEWITT
36 1
References [I] TORDOFF SG, S W E N E Y BP. Acid aspiration prophylaxis in 288
obstetric anaesthetic departments in the United Kingdom. Anaesthesia 1990; 4 5 776-80. [2] GREERS IA, FELLOWS K. Anaphylactoid reaction to ranitidine in labour. British Journal of Clinical Practice 1990; 44: 78. [3] GINT, EWART MC, YAUG, OH TE. Effect of oral omeprazole on intragastric pH and volume in women undergoing elective Caesarean section. British Journal of Anaesrhesia 1990; 6 5 616-9.
The upside down facemask again We read with interest the letter from Drs Northwood and Wade (Anaesthesia 1991; 46: 319) on the use of an upside down Rendell-Baker Soucek mask in patients with a permanent tracheostomy, and applied a similar technique to a different situation. We had been having difficulty in obtaining an airtight seal with a facemask during induction of anaesthesia for patients undergoing transnasal surgery of the pituitary. As many of these patients are acromegalic and the largest mask in our department is a size 5 the problem is fairly obvious! We therefore decided to turn the mask upside down such that the nasal portion of the mask lay over the jaw, whilst the ODA pinched the patient's nose. This, together with the use of a suitable oral airway, proved very
successful in three patients enabling us to ventilate adequately the lungs by hand. Indeed in two of these patients the normal 'chin' portion of the mask actually occluded the nares thus obviating the need to pinch the nostrils. This technique has also proved to be very useful at the end of this and other types of nasal surgery when the presence of nasal packing can make the use of a facemask difficult.
Royal Hallamshire Hospital, GIossop Road, Shefield SIO 2JF
W.C. EDMONDSON A. RUSHTON
Another use for paediatric masks Pre-oxygenation or induction of inhalation anaesthesia through a paediatric mask on the tracheostomy, as described by Drs Northwood and Wade (Anaesthesia 1991; 46: 319), would seem a useful suggestion with the advantage, particularly for infants and children, of not further reducing the available lumen as do the alternatives of wedging a connection or tube into the tracheostomy tube. On occasion, paediatric masks have proven useful to cover the nose only. A 12-year-old, 36 kg male was first seen with a hard, walnut-sized swelling of the right anterior mandible, when 7 years old. Four years elapsed before his next visit to the hospital, little changed, when a biopsy suggested fibrous dysplasia. A year later he came again, complaining of bleeding from an intra-oral swelling, and his haemoglobin was found to be 5 g.dl-'. He was much discomforted by his appearance (Figs 1 and 2) and kept face and neck wrapped in a towel exposing only eyes upwards. A surgical biopsy under general anaesthesia caused profuse bleeding and transfusion of 2 1 of plasmalyte and two units of packed red cells. During the wait for the histology report his haemoglobin fell to 3.8 g.dl-' necessitating more transfusions. These events made the parents extremely reluctant to consent to more surgery for fear of losing their son. At both surgical biopsy and mandible resection inhalation anaesthesia was induced through a paediatric mask over the nose. Lignocaine 4% was applied to the glottis with a Macintosh spray and a 6.5 mm cuffed nasotracheal tube inserted blindly. Lack of access prevented placement of a pharyngeal pack. The plan was to move to the X ray department for angiography and selective vessel embolisation, but an assistant supporting the tumour relaxed at an injudicious time and a section of its attachment tore, precipitating brisk bleeding,
Fig. I .
362
Correspondence
Fig. 2.
fortunately controlled by local pressure, and thence the surgery. In a 3 h procedure the mandible was resected through the premolar regions, Kirchner wires placed, and the mouth floor and buccal mucosa sutured. Anaesthesia included halothane, alcuronium, droperidol, fentanyl, trimetaphan and labetalol. The tracheal tube was removed after 72 h and the patient returned from ICU to the general ward.
In the second postoperative week, salbutamol nebulisation was prescribed for slight wheezing in the chest and the patient soon after discharged with a supply of salbutamol. Only 2 days later at outpatient follow-up, grunting and stridor prompted admission to the ENT ward. A 1 cm length of tracheal stenosis 1.5 cm below the vocal cords was seen at endoscopy and a supraclavicular lymph node biopsy proved full of caseous material. The patient’s trachea was kept intubated for 5 days and antituberculosis medication commenced. Chest X ray showed a mass of mediastinal and lower cervical nodes compressing the trachea. Tracheal biopsy histology reported nonspecific mixed inflammation. After four more general anaesthetics to examine the airways, remove a granuloma and dilate the trachea the patient was once more discharged. The resected specimen measured 20 cm x 17 cm x 17 cm, weighed 3.52 kg and had the histology of ossifying fibroma (probably juvenile or aggressive type).
King Edward VIII Hospital Durban, South Africa
R. WILLIAMSON
‘On/off’ switches on anaesthetic machines Over recent years it has become customary for newly purchased anaesthetic machines to have incorporated a pneumatic switch. This interrupts the flow of all anaesthetic gases apart from the emergency oxygen flush when in the ‘off position. In our view this merely provides another possible source for failure of the gas supply to the patient if the switch malfunctions [l]. We wish to present a case where this in fact occurred, confirming our suspicions. An anaesthetic machine (MIE Cavendish 460) was fully checked by the anaesthetist pre-operatively. Testing included a single hose disconnection test, after the completion of which gas was seen to flow through both the nitrous oxide and oxygen flowmeters. Pipeline and cylinder pressures were checked, as was the security of all connections. The indicator adjacent to the on/off switch was green, with the switch in the up, ‘on’, position. A few minutes later, following the transfer of an anaesthetised patient from the anaesthetic room into the operating theatre, the on/off indicator, which was in the on position, still showed green, but no gas was delivered from the machine other than from the emergency oxygen flush; the nitrous oxide and oxygen flowmeters were open. The patient was returned to the anaesthetic room and the anaesthetic machine was exchanged for another, older, type which did not have a pneumatic on/off switch. This machine worked satisfactorily, allowing anaesthesia and surgery to proceed uneventfully. Subsequent examination of the anaesthetic machine revealed that the switch could be placed in a neutral position, interrupting the gas supply, but with the indicator remaining in the green, ‘on’ position. The pneumatic switch, although robust, clearly has the potential to malfunction after a modest period of use (1 year). Although no overt abnormality was detected when the switch was removed from the machine it was examined and replaced by the MIE service engineer. We are of the opinion that the incorporation of such switches into anaesthetic machines does not enhance patient safety. Royal Hospital for Sick Children, Glasgow G3 8SJ
S.R. HAYNFS C.J. BEST
Reference [I] BEST CJ. Monitoring for anaesthesia. Lancer 1987; ii: 1033-4.
A reply
Thank you for the opportunity to reply to the letter from Drs Haynes and Best. MIE machines, like many other modern anaesthetic machines, are, as Drs Best and Haynes mention, fitted with ‘mains’ on/off switches primarily to turn off the basal flow of oxygen. The switch fitted to the Cavendish 460 in question is a standard component and is purely pneumatic. The action of the switch is designed so that it is extremely difficult to set in a neutral position. With the tests we have carried out, on the actual switch removed from the machine, it has proven impossible to set the switch in a neutral position and at the same time prevent gas flow. Also, the flow indicator adjacent to the switch on our machines can only change from red to green if gas actually flows. We are therefore at a loss as to how this incident has happened. Our engineer, who was called to the hospital and replaced the switch, could not simulate the fault described even after an hour of switching the machine on and off repeatedly. We have had no other reports of this nature in the 6 years we have been fitting these switches, which hopefully shows that the incorporation of such a switch does not compromise patient safety. T. LONGMAN Director of Technical Sales, M & IE, Sowton Industrial Estates, Exeter EX2 7 N A
Guy's Hospital, London SEI 9RT
J.E.S. BARRY R. MADAN P.B. HEWITT
36 1
References [I] TORDOFF SG, S W E N E Y BP. Acid aspiration prophylaxis in 288
obstetric anaesthetic departments in the United Kingdom. Anaesthesia 1990; 4 5 776-80. [2] GREERS IA, FELLOWS K. Anaphylactoid reaction to ranitidine in labour. British Journal of Clinical Practice 1990; 44: 78. [3] GINT, EWART MC, YAUG, OH TE. Effect of oral omeprazole on intragastric pH and volume in women undergoing elective Caesarean section. British Journal of Anaesrhesia 1990; 6 5 616-9.
The upside down facemask again We read with interest the letter from Drs Northwood and Wade (Anaesthesia 1991; 46: 319) on the use of an upside down Rendell-Baker Soucek mask in patients with a permanent tracheostomy, and applied a similar technique to a different situation. We had been having difficulty in obtaining an airtight seal with a facemask during induction of anaesthesia for patients undergoing transnasal surgery of the pituitary. As many of these patients are acromegalic and the largest mask in our department is a size 5 the problem is fairly obvious! We therefore decided to turn the mask upside down such that the nasal portion of the mask lay over the jaw, whilst the ODA pinched the patient's nose. This, together with the use of a suitable oral airway, proved very
successful in three patients enabling us to ventilate adequately the lungs by hand. Indeed in two of these patients the normal 'chin' portion of the mask actually occluded the nares thus obviating the need to pinch the nostrils. This technique has also proved to be very useful at the end of this and other types of nasal surgery when the presence of nasal packing can make the use of a facemask difficult.
Royal Hallamshire Hospital, GIossop Road, Shefield SIO 2JF
W.C. EDMONDSON A. RUSHTON
Another use for paediatric masks Pre-oxygenation or induction of inhalation anaesthesia through a paediatric mask on the tracheostomy, as described by Drs Northwood and Wade (Anaesthesia 1991; 46: 319), would seem a useful suggestion with the advantage, particularly for infants and children, of not further reducing the available lumen as do the alternatives of wedging a connection or tube into the tracheostomy tube. On occasion, paediatric masks have proven useful to cover the nose only. A 12-year-old, 36 kg male was first seen with a hard, walnut-sized swelling of the right anterior mandible, when 7 years old. Four years elapsed before his next visit to the hospital, little changed, when a biopsy suggested fibrous dysplasia. A year later he came again, complaining of bleeding from an intra-oral swelling, and his haemoglobin was found to be 5 g.dl-'. He was much discomforted by his appearance (Figs 1 and 2) and kept face and neck wrapped in a towel exposing only eyes upwards. A surgical biopsy under general anaesthesia caused profuse bleeding and transfusion of 2 1 of plasmalyte and two units of packed red cells. During the wait for the histology report his haemoglobin fell to 3.8 g.dl-' necessitating more transfusions. These events made the parents extremely reluctant to consent to more surgery for fear of losing their son. At both surgical biopsy and mandible resection inhalation anaesthesia was induced through a paediatric mask over the nose. Lignocaine 4% was applied to the glottis with a Macintosh spray and a 6.5 mm cuffed nasotracheal tube inserted blindly. Lack of access prevented placement of a pharyngeal pack. The plan was to move to the X ray department for angiography and selective vessel embolisation, but an assistant supporting the tumour relaxed at an injudicious time and a section of its attachment tore, precipitating brisk bleeding,
Fig. I .
362
Correspondence
Fig. 2.
fortunately controlled by local pressure, and thence the surgery. In a 3 h procedure the mandible was resected through the premolar regions, Kirchner wires placed, and the mouth floor and buccal mucosa sutured. Anaesthesia included halothane, alcuronium, droperidol, fentanyl, trimetaphan and labetalol. The tracheal tube was removed after 72 h and the patient returned from ICU to the general ward.
In the second postoperative week, salbutamol nebulisation was prescribed for slight wheezing in the chest and the patient soon after discharged with a supply of salbutamol. Only 2 days later at outpatient follow-up, grunting and stridor prompted admission to the ENT ward. A 1 cm length of tracheal stenosis 1.5 cm below the vocal cords was seen at endoscopy and a supraclavicular lymph node biopsy proved full of caseous material. The patient’s trachea was kept intubated for 5 days and antituberculosis medication commenced. Chest X ray showed a mass of mediastinal and lower cervical nodes compressing the trachea. Tracheal biopsy histology reported nonspecific mixed inflammation. After four more general anaesthetics to examine the airways, remove a granuloma and dilate the trachea the patient was once more discharged. The resected specimen measured 20 cm x 17 cm x 17 cm, weighed 3.52 kg and had the histology of ossifying fibroma (probably juvenile or aggressive type).
King Edward VIII Hospital Durban, South Africa
R. WILLIAMSON
‘On/off’ switches on anaesthetic machines Over recent years it has become customary for newly purchased anaesthetic machines to have incorporated a pneumatic switch. This interrupts the flow of all anaesthetic gases apart from the emergency oxygen flush when in the ‘off position. In our view this merely provides another possible source for failure of the gas supply to the patient if the switch malfunctions [l]. We wish to present a case where this in fact occurred, confirming our suspicions. An anaesthetic machine (MIE Cavendish 460) was fully checked by the anaesthetist pre-operatively. Testing included a single hose disconnection test, after the completion of which gas was seen to flow through both the nitrous oxide and oxygen flowmeters. Pipeline and cylinder pressures were checked, as was the security of all connections. The indicator adjacent to the on/off switch was green, with the switch in the up, ‘on’, position. A few minutes later, following the transfer of an anaesthetised patient from the anaesthetic room into the operating theatre, the on/off indicator, which was in the on position, still showed green, but no gas was delivered from the machine other than from the emergency oxygen flush; the nitrous oxide and oxygen flowmeters were open. The patient was returned to the anaesthetic room and the anaesthetic machine was exchanged for another, older, type which did not have a pneumatic on/off switch. This machine worked satisfactorily, allowing anaesthesia and surgery to proceed uneventfully. Subsequent examination of the anaesthetic machine revealed that the switch could be placed in a neutral position, interrupting the gas supply, but with the indicator remaining in the green, ‘on’ position. The pneumatic switch, although robust, clearly has the potential to malfunction after a modest period of use (1 year). Although no overt abnormality was detected when the switch was removed from the machine it was examined and replaced by the MIE service engineer. We are of the opinion that the incorporation of such switches into anaesthetic machines does not enhance patient safety. Royal Hospital for Sick Children, Glasgow G3 8SJ
S.R. HAYNFS C.J. BEST
Reference [I] BEST CJ. Monitoring for anaesthesia. Lancer 1987; ii: 1033-4.
A reply
Thank you for the opportunity to reply to the letter from Drs Haynes and Best. MIE machines, like many other modern anaesthetic machines, are, as Drs Best and Haynes mention, fitted with ‘mains’ on/off switches primarily to turn off the basal flow of oxygen. The switch fitted to the Cavendish 460 in question is a standard component and is purely pneumatic. The action of the switch is designed so that it is extremely difficult to set in a neutral position. With the tests we have carried out, on the actual switch removed from the machine, it has proven impossible to set the switch in a neutral position and at the same time prevent gas flow. Also, the flow indicator adjacent to the switch on our machines can only change from red to green if gas actually flows. We are therefore at a loss as to how this incident has happened. Our engineer, who was called to the hospital and replaced the switch, could not simulate the fault described even after an hour of switching the machine on and off repeatedly. We have had no other reports of this nature in the 6 years we have been fitting these switches, which hopefully shows that the incorporation of such a switch does not compromise patient safety. T. LONGMAN Director of Technical Sales, M & IE, Sowton Industrial Estates, Exeter EX2 7 N A
