Effect of ketanserin on sodium nitroprusside requirements, arterial pressure control and heart rate following coronary artery bypass surgery.

In a double-blind, placebo controlled study ketanserin, a serotonin S2 antagonist, was administered to hypertensive patients who had undergone coronary artery bypass surgery. Patients were allocated randomly to receive placebo or ketanserin at an infusion rate of 0.05, 1 or 2 mg kg-1 h-1. Sodium nitroprusside was used as escape medication. Ketanserin reduced the nitroprusside requirements and improved the quality of arterial pressure control in all groups, and this was significant in the low- and high-dose groups. There was a significant decrease in heart rate in the low- and high-dose groups compared with placebo, and no effect in patients who received the medium dose of ketanserin. Ketanserin may be a useful treatment for hypertension following coronary artery surgery as it reduced arterial pressure without reflex tachycardia.

The influence of patient characteristics on the requirements for postoperative analgesia. A reassessment using patient-controlled analgesia.

The requirements for analgesia after upper abdominal surgery were evaluated in 100 patients who received morphine by way of a patient-controlled analgesia system. Hourly and cumulative 24-hour requirements were analysed for possible correlations with patient characteristics and for the patterns of consumption throughout the 24-hour study period. The level of pain relief was assessed by linear analogue pain scores at 4-6 hours and 24 hours. Male patients (n = 46) required significantly more morphine than female patients (n = 54) to achieve similar levels of pain relief (p less than 0.05). There was an inverse correlation between age and morphine consumption in both males and females (r = -0.684, p less than 0.00005 and r = -0.502, p less than 0.00005 respectively). No correlation was found between morphine consumption and patient weight. The pattern of hourly morphine consumption appeared to follow a diurnal rhythm, with peak times of demand at 0900 and 2000 hours. The variations in requirements for analgesia among patients and with time of day should be taken into account when a regimen for postoperative analgesia is prescribed.

The morphine sparing effects of diclofenac sodium following abdominal surgery.

A randomised, double-blind placebo controlled study was undertaken to assess the analgesic efficacy of diclofenac. Following major abdominal surgery and 12 hours later, patients received either placebo or diclofenac 75 mg intramuscularly and their cumulative morphine requirements administered by a patient-controlled system over 24 hours were compared. Pain scores were also measured. Arterial blood gases and coagulation studies were assessed pre- and postoperatively. Morphine consumption was significantly greater in the placebo group (59.5 compared to 38.5 mg, p less than 0.01). Pain scores were significantly lower in the diclofenac group at 4 hours, but not thereafter. Arterial carbon dioxide was significantly increased in the control groups. There was no significant change in platelet count within each group, but a significant difference between the groups (p less than 0.05).

Feedback during patient-controlled analgesia using a speech synthesizer.

Patients who use on-demand analgesia prefer voice feedback rather than buzzer tones to indicate operation of the apparatus. Twenty-four patients had experience of a patient-controlled analgesia apparatus which incorporated a sophisticated feedback of buzzer tones and a speech synthesizer. Of those who expressed a preference, fifteen preferred the speech synthesizer and only one preferred the buzzer tones. The speech synthesizer is a reliable, inexpensive and simple method of supplying feedback to patients when such apparatus is used.

Data collection and analysis from a respiratory inductance plethysmograph.

A respiratory inductance plethysmograph, Respitrace, was used to assess the respiratory effects of narcotic analgesia for the first 24 hours after surgery. Data were collected on-line from the plethysmograph with an Apple][+ microcomputer and stored on disc for later analysis of respiratory rates and tidal volumes, and also periods of central or obstructive apnoea using the difference in phase angle between the abdominal and respiratory components. This involved the measurement of, on average, more than 20,000 breaths per patient and techniques of data compression were required to store this amount of information on a single floppy disc. Frequent nursing interventions reduced the accuracy of tidal volume and phase angle measurements, but respiratory rates were obtained accurately breath by breath.