Sedation in intensive care: morphine and renal function

Abstract

Intravenous morphine infusions have been administered to 12 critically-ill patients during controlled ventilation. Acute oliguric renal failure was present in 4 patients, who were treated with a combination of haemofiltration and haemodialysis. Severity of physiological disturbance was assessed using a modified APACHE Score, level of sedation by a linear-analogue scale, and blood morphine levels by high-pressure liquid chromatography. Morphine clearance was impaired in renal failure, and was dependent on haemofiltration volumes; accumulation of morphine did not occur during this form of treatment. Conscious level was clearly more closely related to the degree of physiological disturbance than blood morphine levels; and for a given blood morphine level, depression of consciousness was more pronounced the greater the degree of physiological disturbance. Use of a physiological sickness score may help to clarify some of the factors influencing cerebral function during critical illness. Careful clinical monitoring of level of sedation is important in patients with oliguric renal failure receiving morphine, and haemofiltration appears to reduce the risk of morphine accumulation in these patients.

Influence of sedation on morbidity and mortality in the intensive care unit

“…1,16,17 Most of the patients in intensive therapy need analgesia, sedation or both, and these are administered in 30 to 50% of seriously ill patients. 1 In recent national survey carried out by the Brazilian Intensive Care Association, 18 fentanyl was the analgesic agent most often used by Brazilian specialists.…”

Opioids and renal function

“…13 Renal replacement therapies might influence morphine clearance, producing a decrease in morphine plasma concentration of 75% with hemofiltration and 45% with dialysis. 15 These techniques appear to extract both morphine and M6G efficiently; M6G is able to pass easier through artificial kidney membrane. 31 Critically ill patients with severe renal failure who required hemofiltration or hemodiafiltration with high-efficiency or highflux membranes while receiving an intravenous infusion of morphine were studied.…”

Haemodynamic and oxygen transport effects of propofol infusion in critically ill adults

“…The infusion protocol was based on pharmacokinetic data from critically ill patients, and was geared to achieve and maintain a blood concentration of around 1 pg.ml-' [q. In fact all patients were excessively sedated at this concentration, probably reflecting their severity of illness (APACHE I1 mean 23; range 15-3 1) since it has been shown that the higher a patient's APACHE I1 score the less will be the sedation requirement [14]. At the end of the study period, propofol infusion rates were reduced to clinically appropriate rates.…”