Pain relief in patients on ventilators

Effect of routine administration of analgesia on energy expenditure in critically ill patients

Measurement of gas exchange using portable metabolic carts to indirectly determine energy expenditure (EE) has been a recent advance in the nutritional management of mechanically ventilated, critically ill patients. Although administration of large doses of morphine has been shown to significantly decrease EE, the influence on EE of morphine given in routine amounts to critically ill patients has not been studied previously. We examined the effect of morphine administration (given as bolus IV injections of 0.10 mg/kg every two hours and continuous IV infusion at 0.05 mg/kg/hr) on EE during rest and various ICU activities in seven mechanically ventilated patients. Morphine administration resulted in a significant reduction in resting EE and total EE of 6.0 and 8.6 percent, respectively. However, EE associated with activities (ie, chest x-ray examination and chest physiotherapy) were not significantly affected by morphine administration. Both bolus and continuous IV morphine infusion had similar effects on EE. Administration of routine doses of morphine significantly decreases total EE in critically ill patients. This should be considered an important factor influencing measurements of EE.

Nitrous oxide for blood pressure control after coronary artery surgery: a dose-response hemodynamic study in postoperative patients

The inhaled anesthetic nitrous oxide is used for sedation in the coronary care unit and has been advocated as an antihypertensive agent in patients after a cardiac operation. To delineate the hemodynamic effects of nitrous oxide after cardiac surgery, we studied 11 patients with a mean age of 63 years who had undergone isolated coronary artery bypass grafting. All patients had major coronary artery disease and normal preoperative hemodynamic function. When patients were in stable condition in the intensive care unit, hemodynamic measurements were made at an inspired oxygen concentration of 40% with progressive doses of nitrous oxide (0, 10, 20, 40, and 60%). Measured and calculated hemodynamic data were compared using analysis of variance. Nitrous oxide caused significant decreases in mean arterial pressure in a dose-related fashion; pressure fell 6 mm Hg at 10% nitrous oxide and 11 mm Hg at 60% nitrous oxide (6 and 13% decreases). These changes were not associated with significant alteration in pulmonary artery pressure or cardiac index. Left ventricular stroke work index decreased significantly with the administration of nitrous oxide. We conclude that, in patients with normal hemodynamic and ventricular function, the administration of nitrous oxide for its sedative and antihypertensive effects is safe in the postoperative period and may be useful, especially in patients who are candidates for early extubation.

The techniques used to sedate ventilated patients. A survey of methods used in 34 ICUs in Great Britain

A survey of sedation techniques for ventilated patients was performed by visiting 34 Intensive Care Units in Great Britain and Northern Ireland. The opiates in frequent used were phenoperidine (21 units - 62% of units), papaveretum (11 - 32%) and morphine (9-26%). Many units used more than one opiate. Levorphanol, buprenorphine, pethidine, fentanyl and codeine were little used. Frequent use of diazepam was found in 22 units (64%), of lorazepam in 11 (32%) and of Althesin in four (12%). Other sedative drugs, droperidol, chlormethiazole, chlorpromazine and ketamine were sued on an occasional basis. Continuous sedation using nitrous oxide was employed in nine (26%) of units-for more than 24 h in six (18%). All units used pancuronium - 31 (91%) used in frequently. Curare was in frequent use in five units (15%). There was wide variation in the way in which the drugs were used. A compromise between the ideal and the practicable method was common, depending more upon shortage of trained nursing staff than upon lack of funds for equipment or expensive drugs. The depth of sedation thought to be ideal depended on the state of the patient as well as the usual practice in the ICU - however a majority (23 = 67%) of units aimed to keep most patients well sedated and detached from the ICU environment. The use of very large doses of opiate to obtain the stress response was thought helpful in only six units (18%) and then in a minority of patients.