Acute kidney injury in major gynaecological surgery: an observational study.

OBJECTIVE: To assess the prevalence, outcomes and cost associated with acute kidney injury (AKI) defined by consensus risk, injury, failure, loss, and end-stage kidney (RIFLE) criteria after gynaecologic surgery. DESIGN: Retrospective single-centre cohort study. SETTING: Academic medical centre. SAMPLE: Two thousand three hundred and forty-one adult women undergoing major inpatient gynaecologic surgery between January 2000 and November 2010. METHODS: AKI was defined by RIFLE criteria as an increase in serum creatinine greater than or equal to 50% from the reference creatinine. We used multivariable regression analyses to determine the association between perioperative factors, AKI, mortality and cost. MAIN OUTCOME MEASURES: AKI, combined major adverse events (hospital mortality, sepsis or mechanical ventilation), 90-day mortality and hospital cost. RESULTS: Overall prevalence of AKI was 13%. The prevalence of AKI was associated with the primary diagnosis. Of women with benign tumour surgeries, 5% (43/801) experienced AKI compared with 18% (211/1159) of women with malignant disease (P < 0.001). Only 1.3% of the whole cohort had evidence of urologic mechanical injury. In a multivariable logistic regression analysis, AKI patients had nine times the odds of a major adverse event compared to patients without AKI (adjusted odds ratio 8.95, 95% confidence interval 5.27-15.22). We have identified several readily available perioperative factors that can be used to identify patients at high risk for AKI after in-hospital gynaecologic surgery. CONCLUSIONS: AKI is a common complication after major inpatient gynaecologic surgery associated with an increase in resource utilisation and hospital cost, morbidity and mortality.

Impairment of vascular endothelial function by high-potassium storage solutions.

High-potassium cold storage solutions are currently used to preserve myocardial function during heart transplantation. However, the effects of high potassium concentration on vascular endothelial function are not well known. We therefore tested vascular rings for endothelial-dependent and endothelial-independent relaxation during storage in normokalemic, normothermic buffers and then in buffers supplemented with 10 to 110 mmol/L KCl. Maximal endothelial-dependent relaxation was significantly reduced at all high potassium concentrations. Endothelial-independent relaxation was impaired only with 80 and 110 mmol/L KCl buffers. Both endothelial-dependent relaxation and endothelial-independent relaxation returned to normal values after washout of excess potassium. Similarly, endothelial-dependent relaxation and endothelial-independent relaxation were assessed in rings after 24 hours of hypothermic storage in normokalemic Krebs buffer, and in buffers containing 20 and 110 mmol/L KCl. Maximal endothelial-dependent relaxation was significantly reduced after preservation in the high-potassium solutions, whereas endothelial-independent relaxation was not impaired. We conclude that there is significant impairment of endothelial function after cold storage in a high-potassium buffer. Inadequate washout of potassium during normothermic conditions may lead to further functional impairment of vascular responsiveness. A low-potassium storage medium is recommended for improved vascular protection.

Denervation of transplanted porcine lung causes airway obstruction.

Lung transplantation can be complicated by a form of small airway obstruction known as bronchiolitis obliterans. We tested the hypothesis that lung denervation causes small airway obstruction in young pigs (10 +/- 1 weeks). Control pigs had an innervated native lobe, and study pigs had either a denervated native lobe or a denervated transplant lobe. Transplanted pigs received standard immunosuppression. At 10 weeks we measured isolated left lobe pulmonary mechanics. Dynamic resistance in both study groups was significantly higher than in the lobectomy group, whereas dynamic compliance in both study groups was significantly lower than in the lobectomy group. No significant difference in resistance or compliance was noted between the transplant and reimplant groups. Histologic changes consistent with rejection were noted in the transplant lobes. We conclude that the small airway obstruction noted in this model is due to operative denervation rather than to immunosuppression or rejection.

The influence of preoperative shock on outcome in sequential endocardial resection for ventricular tachycardia.

Sequential endocardial resection was used in 92 consecutive patients to treat ventricular tachycardia. All patients had coronary artery disease with previous myocardial infarction. All patients had repeated cycles of mapping and resection of arrhythmogenic foci in the normothermic beating heart until ventricular tachycardia was no longer inducible. Eighty-six patients (93%) survived to hospital discharge. The survival rate in patients normotensive at the time of operation was 98% and in patients in shock at the time of operation, 43%. By Cox regression analysis, preoperative shock was the significant predictor (p less than 0.001) of operative mortality. Seventy-four of the 86 operative survivors (86%) had no sustained ventricular tachycardia at initial postoperative electrophysiologic study when receiving no antiarrhythmic drugs. Eighty-three of the 86 operative survivors (97%) had no sustained ventricular tachycardia at final postoperative electrophysiologic study when using antiarrhythmic drugs as needed. After a median follow-up of 21 months (range 1 to 79 months) there were 4 sudden cardiac deaths, 12 other cardiac deaths, and 3 noncardiac deaths. There were no documented nonfatal episodes of sustained monomorphic ventricular tachycardia after hospital discharge. Use of the sequential endocardial resection technique is effective in curing ventricular tachycardia with low operative morbidity and mortality.

Operative risks of the implantable defibrillator versus endocardial resection.

Both map-guided endocardial resection (ER) and the automatic implantable cardioverter defibrillator (AICD) are currently used for surgical treatment of patients who have sustained ventricular tachyarrhythmias. Some authors have preferred AICD implant due to a lower published operative mortality rate. To determine if there is a discrepancy in mortality rates between the two techniques, we analyzed hospital survival in 46 patients undergoing ER and in 44 patients undergoing AICD implantation during the same 3-year period. Two ER patients (4%) died before hospital discharge. Two patients (4%) died after AICD implantation. At predischarge electrophysiologic study five patients (11%) had inducible ventricular tachycardia and received antiarrhythmic drug therapy after ER. In contrast 35 of 42 patients surviving AICD placement received chronic long-term antiarrhythmic therapy (p less than 0.05 compared to ER). Our experience shows that ER and AICD placement may be carried out with similar procedure-related mortality and morbidity rates. Lower operative risks should not be a reason for choosing the AICD over ER for surgical treatment of ventricular tachyarrhythmias. The AICD may actually improve the results of ER by offering an alternative to ventriculotomy in poor-risk surgical candidates.

Anatomic analysis of removed prosthetic heart valves: causes of failure of 33 mechanical valves and 58 bioprostheses, 1980 to 1983.

The details of heart valve prosthesis-associated problems are not widely known. This study investigated the etiologies of the failures of 91 valves, 33 mechanical prostheses and 58 bioprostheses, obtained at reoperation (83) or autopsy (eight) at the Brigham and Women's Hospital during the 42-month period from mid- 1980 through 1983, one to 264 months (mean, 72 months) after valve replacement. Analysis was by gross, histologic, radiographic, and microbiologic examination, as well as review of clinical records. Overall causes of failure included paravalvular leak (15 per cent), thrombosis (7 per cent), tissue overgrowth (8 per cent), degeneration or mechanical failure (43 per cent), and endocarditis (19 per cent). Endocarditis and paravalvular leak were equally frequent with mechanical prostheses and bioprostheses. In addition, thrombosis (18 per cent), tissue overgrowth (21 per cent), and structural failure (12 per cent) were all important failure modes for mechanical prostheses. Sterile degeneration was the overwhelming cause of failure for bioprostheses, accounting for the failure of 35 of 58 (60 per cent) of those recovered. Sterile degeneration took several forms: calcification, with or without cuspal tears (27 cases, 47 per cent of bioprostheses; mean, 77 months, range, 44 to 108 months) and cuspal defects without calcification (eight cases, 14 per cent; mean, 59 months, range, eight to 122 months). In general, calcification increased with time after implantation, but the propensity for the mineralization of bioprostheses varied widely among patients. Four torn valves that had been in place for more than six years had radiographically undetectable calcific deposits. The results of this study indicate that paravalvular leak and endocarditis are frequent causes of failure for all valve types. No clear failure mode predominates with mechanical valve prostheses, although some designs have specific inherent limitations. In contrast, degeneration, especially that related to mineralization, is the most important cause of the late failure of contemporary bioprostheses.