BRITISH JOURNAL OF ANAESTHESIA
1268 INADVERTENT ADMINISTRATION OF 1 0 0 % OXYGEN DURING ANAESTHESIA
N. J. PAYMASTER
Wirral HYPOTENSION FOLLOWING METOCLOPRAMIDE ADMINISTRATION DURING HYFOTENSIVE ANAESTHESIA FOR INTRACRANIAL ANEURYSM
Sir,—Four patients undergoing surgery for repair of a ruptured intracranial aneurysm developed hypotension following the i.v. administration of metoclopramide (Maxolon) as an anti-emetic. All four patients received the same anaesthetic technique TABLE I. Cardiovascular changes following the i.v. administration of metoclopramide 10 mg Before metoclopramide Type of aneurysm (Injection time) Mid-cer. (TA 40)* (TB 100)f Ant. com. (TA28) (TB 60) Ant. com. (TA 32) (TB 68) Post. com. (TA 32) (TB 84)
AP (mm Hg)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
135 80
98
68
90 60
70
54
110 ~70
83
68
120 75
90
64
CVP (mm Hg) 3.6
Type of aneurysm (Injection time) Mid-cer. (TA40) (TB 100) Ant. com. (TA 28) (TB 60) Ant. com. (TA 32) (TB 68) Post. com. (TA 32) (TB 84)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
CVP (mmHg)
85
68
72
2.4
60 70
56
56
—
50 90
67
75
4
55 100
80
70
8
AP (mm Hg)
ert
60 Changes in readings
Type of aneurysm (Injection time)
AP (mm Hg)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
CVP (mm Hg)
Mid cer. (TA40) (TB 100) Ant. com. (TA 28) (TB 60) Ant. com.
— 50
-30
+4
-1.2
20 -20
-14
+2
—
-16
+7
0
(TB 68) Post. com. (TA 32) (TB 84)
-20 15 -20
-10
+6
0
i r\ 10
13
* Time (s) from injection of drug to start in decrease in arterial pressure. •f Time (s) from injection of drug to return of arterial pressure to pre-injection values. AP = Arterial pressure ; M.a.p. = mean arterial pressure j CVP = central venous pressure. Mid cer. = Mid cerebral; ant. com. = anterior communicating; post, com = posterior communicating.
consisting of thiopentone, pancuronium, phenoperidine and nitrous oxide. An e.c.g., indwelling radial arterial line and central venous line, were used for monitoring. All results were recorded on a Sanborn hot-wire chart recorder. Arterial hypotension was induced, by the use of halothane and sodium nitroprusside, to a mean arterial pressure (m.a.p.) of 50 mm Hg. After the aneurysm was clipped the administration of these drugs was stopped. Shortly before closure of the dura, after the effects of the hypotensive agents had ceased, metoclopramide 10 mg was given. This was followed quickly by a decrease in arterial pressure (one patient showing a decrease of 50 mm Hg in systolic arterial pressure) and an increase in
Downloaded from http://bja.oxfordjournals.org/ at University of Manitoba on June 8, 2015
Sir,—Modern anaesthetic machines have a device (usually referred to as "the oxygen bypass" or "emergency oxygen") which enables the anaesthetist to administer high flows of 100% oxygen. When a patient is connected to an anaesthetic machine it is possible to overlook the fact that the emergency oxygen device is in the "on" position and is delivering 100% oxygen. This occurrence is most likely if the device operates quietly and uses a "push-pull" switch. The Cape Waine Mark II anaesthetic machine and ventilator has such a mechanism. Accidents have occurred in our operating theatre on two occasions when patients had been transferred from the anaesthetic room to the operating theatre and connected to a machine. On both occasions a junior anaesthetist failed to notice for some time that the emergency oxygen device was "on" and the paralysed patients received higher concentrations of oxygen than intended. The following day, not unexpectedlyj the patients complained of awareness during anaesthesia. Anaesthetists use the emergency oxygen device frequently at the termination of anaesthesia and, occasionally, during anaesthesia. Sometimes, it is left inadvertently in t i e "on" position after use. Incidents similar to those reported here probably occur more often than is generally believed. They could be avoided by a suitable audio-visual device fitted to the anaesthetic machine warning the anaesthetist that the machine is delivering 100% oxygen.
Maximum change after metoclopramide
1268 INADVERTENT ADMINISTRATION OF 1 0 0 % OXYGEN DURING ANAESTHESIA
N. J. PAYMASTER
Wirral HYPOTENSION FOLLOWING METOCLOPRAMIDE ADMINISTRATION DURING HYFOTENSIVE ANAESTHESIA FOR INTRACRANIAL ANEURYSM
Sir,—Four patients undergoing surgery for repair of a ruptured intracranial aneurysm developed hypotension following the i.v. administration of metoclopramide (Maxolon) as an anti-emetic. All four patients received the same anaesthetic technique TABLE I. Cardiovascular changes following the i.v. administration of metoclopramide 10 mg Before metoclopramide Type of aneurysm (Injection time) Mid-cer. (TA 40)* (TB 100)f Ant. com. (TA28) (TB 60) Ant. com. (TA 32) (TB 68) Post. com. (TA 32) (TB 84)
AP (mm Hg)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
135 80
98
68
90 60
70
54
110 ~70
83
68
120 75
90
64
CVP (mm Hg) 3.6
Type of aneurysm (Injection time) Mid-cer. (TA40) (TB 100) Ant. com. (TA 28) (TB 60) Ant. com. (TA 32) (TB 68) Post. com. (TA 32) (TB 84)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
CVP (mmHg)
85
68
72
2.4
60 70
56
56
—
50 90
67
75
4
55 100
80
70
8
AP (mm Hg)
ert
60 Changes in readings
Type of aneurysm (Injection time)
AP (mm Hg)
M.a.p. (mm Hg)
Heart rate (beat min" 1 )
CVP (mm Hg)
Mid cer. (TA40) (TB 100) Ant. com. (TA 28) (TB 60) Ant. com.
— 50
-30
+4
-1.2
20 -20
-14
+2
—
-16
+7
0
(TB 68) Post. com. (TA 32) (TB 84)
-20 15 -20
-10
+6
0
i r\ 10
13
* Time (s) from injection of drug to start in decrease in arterial pressure. •f Time (s) from injection of drug to return of arterial pressure to pre-injection values. AP = Arterial pressure ; M.a.p. = mean arterial pressure j CVP = central venous pressure. Mid cer. = Mid cerebral; ant. com. = anterior communicating; post, com = posterior communicating.
consisting of thiopentone, pancuronium, phenoperidine and nitrous oxide. An e.c.g., indwelling radial arterial line and central venous line, were used for monitoring. All results were recorded on a Sanborn hot-wire chart recorder. Arterial hypotension was induced, by the use of halothane and sodium nitroprusside, to a mean arterial pressure (m.a.p.) of 50 mm Hg. After the aneurysm was clipped the administration of these drugs was stopped. Shortly before closure of the dura, after the effects of the hypotensive agents had ceased, metoclopramide 10 mg was given. This was followed quickly by a decrease in arterial pressure (one patient showing a decrease of 50 mm Hg in systolic arterial pressure) and an increase in
Downloaded from http://bja.oxfordjournals.org/ at University of Manitoba on June 8, 2015
Sir,—Modern anaesthetic machines have a device (usually referred to as "the oxygen bypass" or "emergency oxygen") which enables the anaesthetist to administer high flows of 100% oxygen. When a patient is connected to an anaesthetic machine it is possible to overlook the fact that the emergency oxygen device is in the "on" position and is delivering 100% oxygen. This occurrence is most likely if the device operates quietly and uses a "push-pull" switch. The Cape Waine Mark II anaesthetic machine and ventilator has such a mechanism. Accidents have occurred in our operating theatre on two occasions when patients had been transferred from the anaesthetic room to the operating theatre and connected to a machine. On both occasions a junior anaesthetist failed to notice for some time that the emergency oxygen device was "on" and the paralysed patients received higher concentrations of oxygen than intended. The following day, not unexpectedlyj the patients complained of awareness during anaesthesia. Anaesthetists use the emergency oxygen device frequently at the termination of anaesthesia and, occasionally, during anaesthesia. Sometimes, it is left inadvertently in t i e "on" position after use. Incidents similar to those reported here probably occur more often than is generally believed. They could be avoided by a suitable audio-visual device fitted to the anaesthetic machine warning the anaesthetist that the machine is delivering 100% oxygen.
Maximum change after metoclopramide
