Epidural fentanyl effect on cardiac output and hepatic blood flow.

Epidural opioids provide high quality analgesia with no clinically apparent effect on the circulation or on specific organ blood flow. Little investigative data is available to support these impressions of circulatory stability. Ten patients presenting for thoracotomy were studied at rest preoperatively to determine if epidural fentanyl had any effect on the systemic circulation or hepatic blood flow. Intravascular pressure measurements, cardiac output estimation using the dye-dilution technique and estimation of altered hepatic blood flow by measuring the clearance of indocyanine green were performed. No significant changes in heart rate, perfusion pressure, cardiac output or hepatic blood flow were detected following the administration of fentanyl 50 micrograms into the epidural space.

Bed rest and postlumbar puncture headache. The effectiveness of 24 hours' recumbency in reducing the incidence of postlumbar puncture headache.

A prospective, blind, randomised trial was undertaken to determine if the incidence of postlumbar puncture headache is significantly altered by 24 hours' recumbency. One hundred and two patients were allocated randomly to rest supine in bed for either 4 or 24 hours after spinal anaesthesia for urological or gynaecological surgery. A standardised spinal anaesthetic technique was applied that incorporated the use of a 22-gauge needle. All patients were followed-up prospectively to determine if there was a difference in the incidence of postlumbar puncture headache between the two groups. Five patients (11.6%) who were recumbent for 4 hours developed postlumbar puncture headache, a result which was not statistically significantly different from the seven patients (11.9%) in the other group who complained of postlumbar puncture headache.

An experimental in vivo study of the canine internal mammary artery and its response to vasoactive drugs.

The internal mammary artery is clearly the preferred conduit for most patients undergoing coronary artery bypass grafting. However, the hemodynamic responses of this graft to vasoactive agents immediately after bypass have not been documented. We have therefore studied blood flow in the canine internal mammary artery after anastomosis to the left anterior descending artery, and its response to epinephrine, metaraminol, isoproterenol, and calcium chloride. Blood flow in the internal mammary artery clearly paralleled changes in systolic blood pressure with perfusion pressure being of prime importance in maintaining flow in the internal mammary artery. No deleterious effect of systemic vasoconstricting agents was demonstrated. We suggest that the administration of these drugs is safe in patients with internal mammary artery grafts.

Reliability of estimation of pulmonary artery wedge pressures during coronary artery bypass surgery.

The ability to reliably estimate pulmonary artery wedge pressure measurements using the clinical and basic cardiovascular parameters was assessed in fifty-six patients having elective coronary artery bypass surgery. The patients were divided into three groups: Group 1 had normal left ventricular function (22 patients), Group 2 had moderate left ventricular dysfunction (20 patients) and Group 3 had more severe left ventricular dysfunction (14 patients). The percentages of correct pulmonary artery wedge pressure estimations were 55%, 56% and 52% in Groups 1, 2 and 3 respectively. We conclude that pulmonary artery wedge pressure measurements can only be reliably estimated from the clinical situation and basic cardiovascular parameters on about 50% of occasions and that the reliability of the estimation does not vary between groups with different left ventricular performance.