Tom Pedersen

Perioperative hemorrhage may depend on coagulation competence and this study evaluated the influence of coagulation competence on blood loss during cystectomy due to bladder cancer. Forty patients undergoing radical cystectomy were included in a randomized controlled trial to receive either lactated Ringer’s solution or Dextran 70 (Macrodex ®) that affects coagulation competence. By thrombelastography evaluated coagulation competence, Dextran 70 reduced “maximal amplitude” (MA) by 25 % versus a 1 % reduction with the administration of lactated Ringer’s solution (P 1500 ml) compared to only four patients (22 %) in the lactated Ringer’s group (P = 0.04). With the use of Dextran 70 vs. lactated Ringer’s solution during cystectomy, a relation between hemorrhage and coagulation competence is demonstrated. Significant bleeding develops based on an about 25 % reduction in thrombelastography determined maximal amplitude. A multivariable model including maximal amplitude discriminates patients with severe perioperative bleeding during cystectomy. The study was accepted on January 7th, 2013 at www.clinicaltrialsregister.eu EudraCT 2012-005040-20 .

The aim of this chapter is to clarify the effect of perioperative monitoring with pulse oximetry and to identify the adverse outcomes that might be prevented or improved by its use. Trials were identified by computerized searches of The Cochrane Library, MEDLINE and EMBASE, and by checking the reference lists of trials and review articles. All controlled trials that randomized patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room, were included in the search. Pulse oximetry monitoring was shown to substantially reduce the extent of perioperative hypoxaemia, enabling the detection and treatment of hypoxaemia and related respiratory events, and promoting several changes in patient care. The implementation of perioperative pulse oximetry monitoring does not significantly reduce the number of postoperative complications, but the question remains whether pulse oximetry can improve outcomes in other situations. Pulse oximetry has been adopted all over the world in clinical practice as a tool that guides anaesthesiologists in the daily management of patients: in teaching situations, in emergencies, and especially in the care of children. Given the relatively small number of patients studied in these trials and the rare events being sought, the studies of perioperative monitoring with pulse oximetry were not able to show an improvement in the outcomes studied.

Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and consequently, correction of perioperative events that might cause postoperative complications or even death. Only a few randomised clinical trials of pulse oximetry have been performed during anaesthesia and in the recovery room which describe perioperative hypoxaemic events, postoperative cardiopulmonary complications and cognitive dysfunction. To study the effect of perioperative monitoring with pulse oximetry to clearly identify the adverse outcomes that might be prevented or improved by the use of pulse oximetry. Trials were identified by computerised searches of the Cochrane Library, MEDLINE, EMBASE, and by checking the reference lists of trials and review articles. All controlled trials that randomised patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room. We collected data in relation to events detectable by pulse oximetry, any serious complications that occurred during anaesthesia or in the postoperative period, intra- or postoperative mortality, and duration of recovery or intensive care stay. Formal statistical synthesis of individual trials was not performed in view of the variety of outcomes studied. Searching identified six reports; four studies with data from a total of 21,773 patients were considered eligible for analysis. Only two studies specifically addressed the outcomes in question; both found no effect on the rate of postoperative complications using perioperative pulse oximetry. Two studies used hypoxaemia detectable by pulse oximetry to assess the value of perioperative monitoring, although outcomes were not given. It was found that hypoxaemia was reduced in the pulse oximetry group both in the operating theatre and in the recovery room. During observation in the recovery room, the incidence of hypoxaemia in the pulse oximetry group was 1.5-3 times less. The postoperative cognitive function using the Wechsler memory scale and continuous reaction time was independent of perioperative monitoring with pulse oximetry. The other study showed that postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group. The two groups did not differ in cardiovascular, respiratory, neurologic, or infectious complications. The duration of hospital stay was a median of 5 days in both groups, and an equal number of in-hospital deaths was registered in the two groups. The studies confirmed that pulse oximetry can detect hypoxaemia and related events. However, we have found no evidence that pulse oximetry affects the outcome of anaesthesia. The conflicting subjective and objective results of the studies, despite an intense, methodical collection of data from a relatively large population, indicates that the value of perioperative monitoring with pulse oximetry is questionable in relation to improved reliable outcomes, effectiveness and efficiency.

Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and, consequently, correction of perioperative events that might otherwise cause postoperative complications or even death. The aim of the study was to clarify the effect of perioperative monitoring with pulse oximetry and to identify the adverse outcomes that might be prevented or improved by its use. Trials were identified by computerized searches of the Cochrane Library, MEDLINE, EMBASE, and by checking the reference lists of trials and review articles. All controlled trials that randomized patients to either pulse oximetry or no pulse oximetry during the perioperative period, including in the operating and recovery room, were included in the study. The search identified six reports. Of these 6 reports, 4 studies with data from 21,773 patients were considered eligible for analysis. Two studies specifically addressed the outcomes in question; both found no effect on the rate of postoperative complications using perioperative pulse oximetry. Hypoxemia was reduced in the pulse oximetry group both in the operating room and in the recovery room. During observation in the recovery room, the incidence of hypoxemia in the pulse oximetry group was 1.5-3 times less. There were postoperative complications in 10% of the patients in the oximetry group and in 9.4% in the control group. The duration of hospital stay was a median of 5 days in both groups, and an equal number of in-hospital deaths was registered in both groups. The studies confirmed that pulse oximetry could detect hypoxemia and related events. However, given the relatively small number of patients studied and the rare events being sought, the studies were not able to show an improvement in various outcomes.

This article illustrates the basic principles of evidence-based medicine and the work within the Cochrane Collaboration and the Cochrane Anesthesia Review Group. It describes how important randomized controlled trials and systematic reviews are in providing the best evidence to answer clinically relevant questions.