Br.J. Anaesth. (1975), 47, 1309

EFFECTS OF PENTOLINIUM ON BLOOD SUGAR AND SERUM POTASSIUM CONCENTRATIONS DURING ANAESTHESIA AND SURGERY N. R. FAHMY AND G. E. BATTIT SUMMARY

Although the use of ganglion-blocking agents to produce deliberate hypotension has been an accepted technique for many years, the effects of these drugs on metabolism have received little attention. The present study reports the effects of pentolinium tartrate (Ansolysen), a clinically useful ganglion-blocking agent, on blood sugar and serum potassium concentrations during general anaesthesia in man. PATIENTS AND METHODS

The studies were conducted on 20 adult patients between the ages of 32 and 69 yr. All underwent total hip replacement under general anaesthesia after a period of food and fluid deprivation. None had clinical or laboratory evidence of pre-existing fluid or electrolyte imbalance, or endocrine, hepatic or renal disease. No family history of diabetes mellitus NABIL R . FAHMY, M.D., F.F.A.R.C.S., GEORGE E . BATTIT, M.D.,

Anaesthesia Laboratories, Harvard Medical School, at the Massachusetts General Hospital, Boston, Massachusetts 02114, U.S.A. Presented in part at the Annual Meeting of the Southern Society of Anesthesiologists, Williamsburg, Virginia, March 20-22, 1975. Correspondence to N. R. F.

was elicited in any patient. The investigation had been approved by the Human Studies Committee at the Massachusetts General Hospital and consent for the study was obtained after the nature of the investigation was explained to each patient. Premedication consisted of morphine sulphate 0.1 mg/kg and hyoscine 0.4mg/70kg (reduced to 0.2 mg/70 kg in patients over 65 yr), given i.m. 1 hr before the induction of anaesthesia. The subjects were divided into two groups of 10. In the control group the arterial pressure was maintained within each patient's normal range, while in the study group arterial hypotension was induced using pentolinium i.v. Anaesthesia was induced with halothane (1-2%), in nitrous oxide and oxygen (3 : 2 litre/min). Endotracheal intubation was performed when a sufficient depth of anaesthesia was achieved, and anaesthesia was maintained with halothane (0.5-1%) in nitrous oxide and oxygen, using a circle system with a soda-lime absorber. Tubocurarine 0.3 mg/kg was administered to provide muscular relaxation. Ventilation was controlled throughout the procedure to maintain Pa COi within the range 35-40 mm Hg. Repeated measurements of Pa COj were obtained. Arterial and right atrial pressures were measured using

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Blood sugar and serum potassium (K+) concentrations were measured before, during and 60 min after surgery in two groups of 10 non-diabetic patients during nitrous oxide/ halothane/tubocurarine anaesthesia. In the control group the arterial pressure was maintained within the patients' normal ranges, while in the study group pentolinium was administered i.v. (average 22 mg per patient) to achieve and maintain a mean arterial pressure of 50mmHg (+10SEM). In the normotensive group the blood sugar concentration increased markedly and significantly during surgery and in the early postoperative period while the serum K + concentration was essentially unchanged. In the hypotensive group pentolinium produced a striking modification of the surgeryinduced hyperglycaemic response (but not to hypoglycaemic values) as well as a small but significant decrease in serum K+ concentration. The observed increase in the blood sugar concentration may be part of the autonomic response to surgical stress. Two mechanisms can explain the reduction in serum K+ concentration: (1) decreased hepatic glycogenolysis and (2) attenuation of the suppressive effect of adrenaline on insulin release, both effects being secondary to the ganglion-blocking property of pentolinium. These results are in contrast to the widely held belief that ganglion-blocking drugs cause hypoglycaemia.

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BRITISH JOURNAL OF ANAESTHESIA

All patients had fasting blood sugar and serum potassium determinations on the day before operation. Seven arterial blood samples were obtained from each patient: before induction (event 1), 45 min after induction of anaesthesia but before pentolinium administration or start of surgery, or both (event 2), 15, 60 and 90 min after surgery had begun (events 3, 4 and 5), 15 min before conclusion of the operation (event 6) and 1 hr after the termination of

surgery (event 7). The samples were analysed for blood sugar, Po 2 , Pco 2 , pH, serum potassium and serum sodium. The blood sugar concentration was measured (within 1 hr of sampling) in duplicate as total reducing substances by the Auto Analyzer (Technicon) ferricyanide method. The reproducibility of this colorimetric technique is within 2%. Determinations by this method agree within 5% when compared with the glucose oxidase technique. The concentrations of serum electrolytes were determined using an Instrumentation Laboratories flame photometer, Model 143, the laboratory error of which is ±0.1 m-equiv/litre for potassium and + 2 m-equiv/ litre for sodium. Blood gas tensions and pH values were determined with standard electrodes at 37 °C and the values were corrected to the measured body temperature (Kelman and Nunn, 1966). Data analyses were performed using the Student t test with P< 0.05 accepted as the level of significance. In either group the sample before surgery (event 2) from each patient was considered as the control and subsequent samples were compared with it (paired data). The two groups were related to each other (unpaired data) by comparing the data from samples drawn at each event. RESULTS

Table I shows the statistical analysis of the data, and figure 1 illustrates the average percentage changes in the blood glucose and serum potassium concentrations.

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pressure transducers (Hewlett-Packard type 267 BC) and were recorded continuously, together with lead II of the e.c.g., on a Sanborn 4-channel pen recorder. In the study group, pentolinium tartrate was administered (45 min after induction) by i.v. injection before surgery and, at varying intervals thereafter, in doses sufficient to maintain the mean arterial pressure at 50 mm Hg (+ 10 SEM). The average dose was 22 mg per patient. Absence of the post-Valsalva arterial pressure overshoot, as well as steady hypotension, tachycardia and pupillary dilatation, were considered to be evidence of adequate ganglion blockade. Physiological saline was infused at a rate of 5 ml/kg/hr. Albumin (5% in saline) and packed red cells were administered to replace the measured blood loss which was determined by weighing sponges and measuring the volume of blood collected in the suction bottles. In the study group, 405 ml (SEM 41 ml) of albumin and 245 ml (SEM 22 ml) of packed red cells were infused, while in the control group 595 ml (SEM 50) of albumin and 535 ml (SEM 50) of packed red cells were used during the investigation. No glucose was administered during the study.

TABLE I. Comparison of blood sugar (mg/100 ml), serum potassium (m-equivllitre) and mean arterial pressure (mm Hg) before and after pentolinium or start of surgery. (Values are mean + SEM; n.s. — not significant) After start of surgery (min)

15 min UClUiC

C11U

f\C\ m i nflftpr \}\J llllii a l l v l

induction

Baseline

15

60

90

of surgery

surgery

Study group (n = 10) Blood sugar

79-2 ± 4 0

86-8±5-l

Serum K+

3-86 ±006

3-86 + 006

Mean arterial pressure 92-8 ±2-54

86-8 + 2-47

86-8 ±5-4 n.s. 3-68 + 0-08 P < 0-005 57-9 ±1-84 P < 0-005

94-8 ± 4 0 P

Effects of pentolinium on blood sugar and serum potassium concentrations during anaesthesia and surgery.

Blood surgar and serum potassium (K+) concentrations were measured before, during and 60 min after surgery in two groups of 10 non-diabetic patients d...
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