Br.J. Anaesth. (1978), 50, 937
CHANGES IN PLASMA CONCENTRATION OF ADRENALINE AND NORADRENALINE IN ANAESTHETIZED PATIENTS DURING SODIUM NITROPRUSSIDE-INDUCED HYPOTENSION W. A. L. RAWLINSON, A. B. LOACH AND C. R. BENEDICT SUMMARY
The use of sodium nitroprusside (sodium nitrosopentacyanoferrate, SNP) to induce arterial hypotension during neurosurgical anaesthesia was described first by Moraca and others (1962) and its use during surgery of intracranial aneurysms by Siegel, Moraca and Green (1971). Hypotension is known to stimulate baroreceptors and is thought to lead to increased sympatho-adrenal activity. Some indication of sympatho-adrenal medullary function may be obtained from changes in plasma concentrations of adrenaline and noradrenaline (Nikki et al., 1972). Therefore, the plasma adrenaline and noradrenaline concentrations were measured before, during and after infusion of SNP in two groups of patients during general anaesthesia. One group consisted of young, healthy adults undergoing elective middle ear surgery; the other consisted of patients undergoing neurosurgery following subarachnoid haemorrhage. PATIENTS AND METHODS
We investigated five healthy patients (three males and two females, aged 18-34 yr) undergoing middle W. A. L. RAWLINSON, M.A., B.M., B.CH., F.F.A.R.C.S. ; A. B. LOACH, M.A., M.B., F.F.A.R.C.S.; Nuffield Department of Anaesthetics. C. R. BENEDICT,* M.B., B.S., D.PHIL., MRC
and University Department of Clinical Pharmacology. Radcliffe Infirmary, Oxford OX2 6HE. * Present address: Johns Hopkins Hospital, Baltimore, U.S.A. 0007-0912/78/0050-0937 $01.00 75
ear surgery (group 1), and eight patients (three males and five females, aged 40-62 yr) undergoing neurosurgery for subarachnoid haemorrhage (group 2). Papaveretum 15-20 mg and hyoscine 0.3-0.4 mg was given i.m. to the patients in group 1 1 h before induction of anaesthesia. The patients in group 2 received droperidol 0.1 mg kg" 1 and atropine 0.6 mg i.m. Anaesthesia was induced with thiopentone 4 mg kg" 1 and suxamethonium 1 mg kg" 1 , the larynx was sprayed with 5 ml of 4% lignocaine, and the trachea was intubated. The lungs were ventilated artificially to normocapnia with 66% nitrous oxide in oxygen. Tubocurarine 0.5 mg kg" 1 was given initially, and anaesthesia was supplemented with increments of fentanyl 0.05-0.1 mg every 30 min. Arterial pressure was monitored continuously with an indwelling arterial cannula connected to a transducer and an oscilloscope with a digital display. The e.c.g. was monitored continously. SNP was administered as 0.01 % solution in normal saline using a 100-ml "Metriset" infusion set via a catheter inserted into the superior vena cava. The rate of infusion of SNP was sufficient to provide adequate hypotension for good operating conditions. No attempt was made to reduce mean arterial pressure to less than 60mmHg, as this was not necessary. The total dose • of SNP was always less than the recommended maximum of 1.5 mg kg - 1 (5 (imol kg" 1 ) (Vesey, Cole and Simpson, 1975, 1976). © Macmillan Journals Ltd 1978
Downloaded from http://bja.oxfordjournals.org/ at University of Sussex on August 24, 2015
Changes in plasma concentrations of adrenaline and noradrenaline were measured when sodium nitroprusside (SNP) was used for the induction of hypotension in healthy adults undergoing middle ear surgery (group 1) and patients undergoing neurosurgery for subarachnoid haemorrhage (group 2). The mean catecholamine concentrations before the infusion of SNP were four to five times greater in group 2 than in group 1. Group 1 showed significant increases in plasma catecholamines during hypotension induced with SNP, the increase correlating significantly with the degree of hypotension and the rate of infusion of SNP. Group 1 showed an increase in heart rate of about 10%, which could not be related to the catecholamine concentrations. In group 2, changes in plasma catecholamines following infusion of SNP were inconsistent. This may have been because the sympatho-adrenal medullary system was already maximally active and was unable to respond further to induced hypotension.
BRITISH JOURNAL OF ANAESTHESIA
938 Measurement of plasma catecholamine concentrations
RESULTS
The plasma adrenaline and noradrenaline concentrations before SNP was infused were considerably higher in group 2 than in group 1 (ratios of concentrations in group 2/group 1 for adrenaline = 5.28 and for noradrenaline = 4.45). These differences are statistically significant (adrenaline P
CHANGES IN PLASMA CONCENTRATION OF ADRENALINE AND NORADRENALINE IN ANAESTHETIZED PATIENTS DURING SODIUM NITROPRUSSIDE-INDUCED HYPOTENSION W. A. L. RAWLINSON, A. B. LOACH AND C. R. BENEDICT SUMMARY
The use of sodium nitroprusside (sodium nitrosopentacyanoferrate, SNP) to induce arterial hypotension during neurosurgical anaesthesia was described first by Moraca and others (1962) and its use during surgery of intracranial aneurysms by Siegel, Moraca and Green (1971). Hypotension is known to stimulate baroreceptors and is thought to lead to increased sympatho-adrenal activity. Some indication of sympatho-adrenal medullary function may be obtained from changes in plasma concentrations of adrenaline and noradrenaline (Nikki et al., 1972). Therefore, the plasma adrenaline and noradrenaline concentrations were measured before, during and after infusion of SNP in two groups of patients during general anaesthesia. One group consisted of young, healthy adults undergoing elective middle ear surgery; the other consisted of patients undergoing neurosurgery following subarachnoid haemorrhage. PATIENTS AND METHODS
We investigated five healthy patients (three males and two females, aged 18-34 yr) undergoing middle W. A. L. RAWLINSON, M.A., B.M., B.CH., F.F.A.R.C.S. ; A. B. LOACH, M.A., M.B., F.F.A.R.C.S.; Nuffield Department of Anaesthetics. C. R. BENEDICT,* M.B., B.S., D.PHIL., MRC
and University Department of Clinical Pharmacology. Radcliffe Infirmary, Oxford OX2 6HE. * Present address: Johns Hopkins Hospital, Baltimore, U.S.A. 0007-0912/78/0050-0937 $01.00 75
ear surgery (group 1), and eight patients (three males and five females, aged 40-62 yr) undergoing neurosurgery for subarachnoid haemorrhage (group 2). Papaveretum 15-20 mg and hyoscine 0.3-0.4 mg was given i.m. to the patients in group 1 1 h before induction of anaesthesia. The patients in group 2 received droperidol 0.1 mg kg" 1 and atropine 0.6 mg i.m. Anaesthesia was induced with thiopentone 4 mg kg" 1 and suxamethonium 1 mg kg" 1 , the larynx was sprayed with 5 ml of 4% lignocaine, and the trachea was intubated. The lungs were ventilated artificially to normocapnia with 66% nitrous oxide in oxygen. Tubocurarine 0.5 mg kg" 1 was given initially, and anaesthesia was supplemented with increments of fentanyl 0.05-0.1 mg every 30 min. Arterial pressure was monitored continuously with an indwelling arterial cannula connected to a transducer and an oscilloscope with a digital display. The e.c.g. was monitored continously. SNP was administered as 0.01 % solution in normal saline using a 100-ml "Metriset" infusion set via a catheter inserted into the superior vena cava. The rate of infusion of SNP was sufficient to provide adequate hypotension for good operating conditions. No attempt was made to reduce mean arterial pressure to less than 60mmHg, as this was not necessary. The total dose • of SNP was always less than the recommended maximum of 1.5 mg kg - 1 (5 (imol kg" 1 ) (Vesey, Cole and Simpson, 1975, 1976). © Macmillan Journals Ltd 1978
Downloaded from http://bja.oxfordjournals.org/ at University of Sussex on August 24, 2015
Changes in plasma concentrations of adrenaline and noradrenaline were measured when sodium nitroprusside (SNP) was used for the induction of hypotension in healthy adults undergoing middle ear surgery (group 1) and patients undergoing neurosurgery for subarachnoid haemorrhage (group 2). The mean catecholamine concentrations before the infusion of SNP were four to five times greater in group 2 than in group 1. Group 1 showed significant increases in plasma catecholamines during hypotension induced with SNP, the increase correlating significantly with the degree of hypotension and the rate of infusion of SNP. Group 1 showed an increase in heart rate of about 10%, which could not be related to the catecholamine concentrations. In group 2, changes in plasma catecholamines following infusion of SNP were inconsistent. This may have been because the sympatho-adrenal medullary system was already maximally active and was unable to respond further to induced hypotension.
BRITISH JOURNAL OF ANAESTHESIA
938 Measurement of plasma catecholamine concentrations
RESULTS
The plasma adrenaline and noradrenaline concentrations before SNP was infused were considerably higher in group 2 than in group 1 (ratios of concentrations in group 2/group 1 for adrenaline = 5.28 and for noradrenaline = 4.45). These differences are statistically significant (adrenaline P
