The impact of off-pump coronary artery bypass surgery on postoperative renal function.

OBJECTIVES: A number of risk factors have been recognised for postoperative renal dysfunction following on-pump coronary artery bypass surgery (CABG). There are, however, few studies that have evaluated the potential reno-protective effects of off-pump CABG in the presence of other confounding risk factors. The aim of this study was to determine if off-pump CABG reduces the risk of renal injury. METHODS: Serum creatinine values (preoperatively and day 1, 2 and 4 postoperatively) and other clinical data were prospectively collected on 1580 consecutive patients who underwent first-time CABG from 2002 to 2005. Creatinine clearance was calculated using the Cockcroft and Gault equation. The effect of on-pump vs. off-pump CABG on renal function was analysed, adjusting for age, gender, diabetes mellitus, left ventricular (LV) function and preoperative creatinine clearance, using multiple regression analysis. RESULTS: One thousand one hundred and forty-five (73%) patients underwent on-pump CABG and 435 (27%) underwent off-pump CABG. The two groups were similar with respect to age, gender and diabetes. Two hundred and seventy-four (17%) patients were females and 274 (17%) patients had diabetes. Multivariate analysis demonstrated significantly lower creatinine clearance postoperatively in patients with diabetes (P<0.001) and advanced age (P<0.001). The on-pump group had significantly lower postoperative creatinine clearance in comparison to the off-pump group (P= 0.01). The effect remained consistent after adjusting for potential risk factors (age, diabetes, gender, LV function and preoperative creatinine clearance) in the multivariate analysis. CONCLUSION: Off-pump surgery is associated with a reduction in postoperative renal injury.

Effect of glycaemic control on complications following cardiac surgery: literature review.

INTRODUCTION: No uniform consensus in the UK or Europe exists, for glycaemic management of patients with Diabetes or pre-diabetes undergoing cardiac surgery. OBJECTIVE: [i] Determine the relationship between glycaemic control and cardiac surgical outcomes; [ii] Compare current vs gold standard management of patients with Diabetes or pre-diabetes undergoing cardiac surgery. METHODS: Searches of MEDLINE, NHS Evidence and Web of Science databases were completed. Articles were limited to those in English, German and French. No date limit was enforced.13,232 articles were identified on initial literature review, and 50 relevant papers included in this review. RESULTS: No national standards for glycaemic control prior to cardiac surgery were identified. Upto 30% of cardiac surgical patients have undiagnosed Diabetes. Cardiac surgical patients without Diabetes with pre-operative hyperglycaemia have a 1 year mortality double that of patients with normoglyacemia, and equivalent to patients already diagnosed with Diabetes. Pre- and peri-operative hyperglycaemia is associated with worse outcomes. Evidence regarding tight glycaemic control vs moderate glycaemic control is conflicting. Tight control may be more effective in patients without Diabetes with pre-/peri-operative hyperglycaemia, and moderate control appears more effective in patients with pre-existing Diabetes. Patients with well controlled Diabetes may achieve comparable outcomes to patients without Diabetes with similar glycaemic control. CONCLUSIONS: Pre / peri-operative hyperglycaemia is associated with worse outcomes in both patients with, and without Diabetes undergoing CABG. This review supports the pre-operative screening, and optimisation of glycaemic control in patients undergoing cardiac surgery. Optimal glycaemic management remains unclear and clear guidelines are needed.

The prolongation of local anaesthetic action with dextran. The effect of molecular weight.

Field blocks of the inguinal region were performed in two groups of patients, in one group using a mixture of 0.5% bupivacaine, 1:200 000 adrenaline and dextran 110 and in the second group using a mixture of 0.5% bupivacaine, 1:200 000 adrenaline and dextran 150; the study being performed in a double-blind fashion. The dextran 150 mixture produced a highly significant increase (p less than 0.01) in the duration of the block when compared with the dextran 110 mixture. The authors conclude that the use of dextran of increasing molecular weight increases the duration of action of local anaesthetics correspondingly.

Vaginal delivery in a patient with a phaeochromocytoma. A case report.

In pregnancy complicated by phaeochromocytoma, successful management has usually entailed elective Caesarean section followed by removal of the tumour. We report a successful vaginal delivery, undertaken under extradural blockade, in a patient with proven phaeochromocytoma.

Effect of etomidate on the auditory evoked response in man.

The effect of etomidate on the auditory evoked response was examined in a double-blind study carried out before the start of surgery. Fourteen patients were anaesthetized with 70% nitrous oxide and oxygen after induction with thiopentone. Ventilation was controlled. Seven of the patients received a continuous infusion of etomidate, increasing in five equal steps from 0.01 mg kg-1 min-1 to 0.05 mg kg-1 min-1 over a period of 50 min. The other seven received similarly an equivalent volume of saline. The patients given etomidate were easily distinguishable from those given saline, solely on the basis of changes in the early cortical peaks Pa and Nb. In the etomidate group the latencies of these peaks increased and their amplitudes decreased. These changes were linearly related to serum etomidate concentration. There was no effect of etomidate on the brainstem response.

Selective effect of althesin on the auditory evoked response in man.

The auditory evoked response (AER) has been studied in six patients before the induction of general anaesthesia, during anaesthesia with nitrous oxide in oxygen and mechanical ventilation, then with a stepwise increasing rate of infusion of Althesin ranging from 18 micrograms kg-1 min 1 to 90 micrograms kg-1 min-1. The sections of the AER examined in this study were the brainstem waves I, III and V and the early cortical waves Pa and Nb. There were dose-related changes in latency and amplitude of waves Pa and Nb, latency increasing and amplitude diminishing with increasing concentrations of alphaxalone as measured in venous blood. In contrast, there were no changes in either latency or amplitude of the brainstem waves. This is consistent with other work suggesting that Althesin has little effect on neuronal function below the level of the superior colliculus.

Effect of isoflurane on the auditory evoked response in man.

We have examined the effects of isoflurane (0.6-2.9% end-tidal) on the auditory evoked response (AER) in six patients before elective surgery. Isoflurane produced significant dose-related changes in the AER: reductions in amplitude and increases in latency of the cortical waves Pa and Nb, and increases in the latency of the brainstem waves III and V. When isoflurane was compared with halothane and enflurane using an MAC-based comparison, we found no differences in the effect of the three agents on the amplitude of the early cortical waves, although the latencies showed significant differences. The consistent dose-related effect on the amplitudes of the cortical waves implies that the AER could be a promising index of the depth of anaesthesia.

Bronchiolectasis caused by positive end-expiratory pressure.

Bronchiolectasis in patients with respiratory failure who are ventilated artificially with positive end-expiratory pressure (PEEP) appears to be associated with increased physiologic dead space. We found that the survival rate of 40 patients ventilated with PEEP was not significantly different from that of a control series of patients not receiving PEEP. Pulmonary function values, including the dead-space/tidal-volume ratio, returned to normal for the five PEEP patients in whom these variables were measured.