674
Correspondence
3. MCCONN,R. & DELGUERCIO, L.R.M. (1971) The respiratory function of blood and the effect of steroids. Annals of Surgery, 174,436.
haemoglobin dissociation. Critical Care Medicine, 1, 26. 5 . LILLIHEI, R.C. & MACCLEAN, L.D. (1959) Physio-
4. BRYAN-BROWN, C.W.S., BAEK,S.M., M A K A R A L I , G. & SHOEMAKER, W.C. (1973) Consumable oxygen: study of oxygen availability in relation to oxy-
logical approach to successful treatment of endotoxic shock in the experimental animal. Archires of Surgery, 78,464.
Anaesthesia and the carcinoid syndrome during manipulation of the tumour) we have not Drs Mason and Steane (Anaesthesia, 1976, 31, 228) found them to pose serious threats to the patient’s provided an excellent account and survey of the literature concerning the anesthetic management wellbeing. Particular care is necessary following such procedures as bowel resection, cholecystectomy or of patients undergoing surgery for the carcinoid liver biopsy all of which may enhance fluid and syndrome. Our own experience of this condition leads us to believe that hypovalaemia before surgery protein loss. Hepatic artery ligation may be followed is a major complicating factor and one which may by necrosis of liver metastases with transiently well be overlooked. increased bradykinin liberation and, again, falls in blood pressure may occur. However, in all these We have found that severe hypotension during or conditions, the maintenance of normovolaemia after surgery is one of the greatest problems and we minimises the disturbance and severe or protracted do not believe that this is always due to circulating bradykinins since in none of our patients was the hypotension can be avoided. fall in blood pressure accompanied by flushing or We would also like to stress the importance of adequate intraoperative analgesia in these patients bronchospasm; hypovolaemia seemed to be a more and underline the need for meticulous postoperative likely cause. A history of flushing and of diarrhoea intensive care. should alert the anaesthetist to the co-existence of, occasionally, quite severe dehydration as should signs of poor tissue perfusion and a reduced urinary Ziekenhuis Ziekenzorg, J.W. KLEINE output. Surprisingly, however, we have found Vereniging Ziekenzorg, Y.H.KHOUW biochemical homeostasis to be well preserved. De Ruyterlaan 5, M.G. HEERES Preoperative preparation to ensure an adequate circulating blood volume minimises the fluctuations 7511 Enschede, in blood pressure during and after surgery and, Nederlands. The editor regrets the delay in publishing this letter. although some alterations do occur (particularly The safe use of sodium nitroprusside We were very interested to see the correspondence (Anaesthesia, 1979, 34,74) following Dr P.V. Cole’s paper ‘The safe use of sodium nitroprusside’ (Anaesthesia 1978, 33, 473) and would like to comment on the two points raised by Drs Verner, Smith and Cole-namely the method of ventilation and the type of pressure monitoring employed. We have studied the respiratory effects of induced hypotension with nitroprusside. Spontaneous, ventilation with halothane following diazepam premedication (which we find very satisfactory) was not associated with carbon dioxide levels similar to those described by Dr Cole after opiate premedication. Further we found that artificial ventilation does not prevent the fall in arterial oxygen tension that occurs when nitroprusside is infused. We would suggest that an FIo, of 50% is safer than 40% in the older patient. Dr Cole prefers artificial ventilation as it enables him to reduce the total dosage of nitroprusside used. Certainly young fit patients d o occasionally require total doses of nitroprusside which could exceed 1-5 mg/kg but we prefer to change over to trimetaphan, rather than resort to
artificial ventilation (which increases central venous pressure and therefore venous oozing, and also abolishes a valuable monitor of cerebral perfusionthe rate and rhythm of respiration). Trimetaphan produces a drier operative field, the ultimate aim in these resistant patients, and avoids nitroprusside toxicity. With regard to monitoring, we feel that an arterial line is the method of choice. The continuous display of blood pressure during the infusion of such a potent drug makes control of the rate of administration much easier as alterations in response are instantly visible. Royal Infirmary of Edinbrrgh, buriston Place, Edinburgh EH3 9 YW
J.A.W. WILDSMITH G.B. DRUMMOND W.R. MACRAE
Reference 1. WILDSMITH, J.A.W., DRUMMOND, G.B. & MACRAE, W.R. (1975) Blood gas changes during induced
hypotension with sodium nitroprusside. British Journal of Anaesthesia, 41, 1205.
Correspondence
3. MCCONN,R. & DELGUERCIO, L.R.M. (1971) The respiratory function of blood and the effect of steroids. Annals of Surgery, 174,436.
haemoglobin dissociation. Critical Care Medicine, 1, 26. 5 . LILLIHEI, R.C. & MACCLEAN, L.D. (1959) Physio-
4. BRYAN-BROWN, C.W.S., BAEK,S.M., M A K A R A L I , G. & SHOEMAKER, W.C. (1973) Consumable oxygen: study of oxygen availability in relation to oxy-
logical approach to successful treatment of endotoxic shock in the experimental animal. Archires of Surgery, 78,464.
Anaesthesia and the carcinoid syndrome during manipulation of the tumour) we have not Drs Mason and Steane (Anaesthesia, 1976, 31, 228) found them to pose serious threats to the patient’s provided an excellent account and survey of the literature concerning the anesthetic management wellbeing. Particular care is necessary following such procedures as bowel resection, cholecystectomy or of patients undergoing surgery for the carcinoid liver biopsy all of which may enhance fluid and syndrome. Our own experience of this condition leads us to believe that hypovalaemia before surgery protein loss. Hepatic artery ligation may be followed is a major complicating factor and one which may by necrosis of liver metastases with transiently well be overlooked. increased bradykinin liberation and, again, falls in blood pressure may occur. However, in all these We have found that severe hypotension during or conditions, the maintenance of normovolaemia after surgery is one of the greatest problems and we minimises the disturbance and severe or protracted do not believe that this is always due to circulating bradykinins since in none of our patients was the hypotension can be avoided. fall in blood pressure accompanied by flushing or We would also like to stress the importance of adequate intraoperative analgesia in these patients bronchospasm; hypovolaemia seemed to be a more and underline the need for meticulous postoperative likely cause. A history of flushing and of diarrhoea intensive care. should alert the anaesthetist to the co-existence of, occasionally, quite severe dehydration as should signs of poor tissue perfusion and a reduced urinary Ziekenhuis Ziekenzorg, J.W. KLEINE output. Surprisingly, however, we have found Vereniging Ziekenzorg, Y.H.KHOUW biochemical homeostasis to be well preserved. De Ruyterlaan 5, M.G. HEERES Preoperative preparation to ensure an adequate circulating blood volume minimises the fluctuations 7511 Enschede, in blood pressure during and after surgery and, Nederlands. The editor regrets the delay in publishing this letter. although some alterations do occur (particularly The safe use of sodium nitroprusside We were very interested to see the correspondence (Anaesthesia, 1979, 34,74) following Dr P.V. Cole’s paper ‘The safe use of sodium nitroprusside’ (Anaesthesia 1978, 33, 473) and would like to comment on the two points raised by Drs Verner, Smith and Cole-namely the method of ventilation and the type of pressure monitoring employed. We have studied the respiratory effects of induced hypotension with nitroprusside. Spontaneous, ventilation with halothane following diazepam premedication (which we find very satisfactory) was not associated with carbon dioxide levels similar to those described by Dr Cole after opiate premedication. Further we found that artificial ventilation does not prevent the fall in arterial oxygen tension that occurs when nitroprusside is infused. We would suggest that an FIo, of 50% is safer than 40% in the older patient. Dr Cole prefers artificial ventilation as it enables him to reduce the total dosage of nitroprusside used. Certainly young fit patients d o occasionally require total doses of nitroprusside which could exceed 1-5 mg/kg but we prefer to change over to trimetaphan, rather than resort to
artificial ventilation (which increases central venous pressure and therefore venous oozing, and also abolishes a valuable monitor of cerebral perfusionthe rate and rhythm of respiration). Trimetaphan produces a drier operative field, the ultimate aim in these resistant patients, and avoids nitroprusside toxicity. With regard to monitoring, we feel that an arterial line is the method of choice. The continuous display of blood pressure during the infusion of such a potent drug makes control of the rate of administration much easier as alterations in response are instantly visible. Royal Infirmary of Edinbrrgh, buriston Place, Edinburgh EH3 9 YW
J.A.W. WILDSMITH G.B. DRUMMOND W.R. MACRAE
Reference 1. WILDSMITH, J.A.W., DRUMMOND, G.B. & MACRAE, W.R. (1975) Blood gas changes during induced
hypotension with sodium nitroprusside. British Journal of Anaesthesia, 41, 1205.
