Perioperative cardiac biomarkers: the utility and timing.

PURPOSE OF REVIEW: We presume that biomarkers will improve identification of patients at risk, leading to interventions and treatments that reduce perioperative adverse events. Risk stratification is multifactorial, and a biomarker must add information to this process, thereby redistributing patients to either higher or lower risk categories, to improve the allocation of expensive and risky interventions. This review focuses on the utility of three cardiac biomarkers in perioperative management. RECENT FINDINGS: Using newly defined epidemiologic criteria, three distinct molecules, brain natriuretic peptide (BNP), troponin (cTn), and glycosylated hemoglobin (HbA1c) emerge as potentially useful in perioperative medicine. A meta-analysis shows, in vascular surgery, BNP improves risk stratification. Four articles highlight the utility of postoperative cTn measurements in cases of myocardial injury. These articles show that most injury is not infarction, and they present preliminary evidence of the populations that will benefit from structured surveillance protocols. HbA1c is shown to improve the prediction of mortality, but there are questions whether this risk is modifiable. SUMMARY: The findings here suggest an expanded role for postoperative cTn surveillance; however, the precise populations that benefit, or the interventions required, are not yet defined. The encouraging data for the other two biomarkers need more investigations before adopting them into routine clinical use.

Incidence of urinary retention in patients with thoracic patient-controlled epidural analgesia (TPCEA) undergoing thoracotomy.

Up to 100% of patients treated with epidural analgesia can experience urinary retention, which may be related to dermatomal level of the epidural block, epidural medication, and surgical procedure. This study was designed to identify the incidence of urinary retention in patients who receive thoracic patient-controlled epidural analgesia (TPCEA) after thoracotomy. Forty-nine patients were enrolled and received epidural infusion of ropivacaine 0.2% or mixture of bupivacaine 0.1% with hydromorphone 0.015 mg/mL. Epidural catheter placement level was verified by chest X-rays. Indwelling urinary catheters were removed between 12 and 48 h after surgery when no longer required for fluid monitoring. Four hours later, patients were assessed for urinary retention using bladder ultrasound. Residual bladder volume was recorded, and urinary retention was defined as an inability to void or a bladder volume of greater than 600 mL at 4 h. Twenty-four hours after the catheter removal, patients completed a questionnaire to assess their perception of the indwelling catheter before and after its removal. Five participants (approximately 10%) with epidural catheters between T3 and T5 with bupivacaine/hydromorphone epidural solution were recatheterized. No association was established between catheter level, drug type, infusion rate, and urinary retention. Although 76% of patients did not report any physical discomfort with the indwelling urinary catheter, 66% felt relief after its removal and 18% did not ambulate with the inserted urinary catheter. The incidence of postoperative urine retention was low (10%), indicating that unless required for other purposes, indwelling urinary catheters may be removed between 12 and 48 h after surgery while receiving TPCEA.

Comparison of propofol-based versus volatile-based anaesthesia and postoperative sedation in cardiac surgical patients: a prospective, randomized, study.

BACKGROUND: Clinical trials have shown conflicting results regarding the use of volatile anaesthesia before or after an ischaemic insult in cardiac surgical patients and its effect on myocardial injury. This may be attributable to the failure of continuing volatile agents into the early postoperative period. We hypothesised that combined volatilebased anaesthesia and postoperative sedation would decrease the extent of myocardial injury after coronary artery bypass grafting (CABG) when compared with an intravenous, propofol-based approach. This study aimed to assess the feasibility of the perioperative protocol and investigate whether volatile anaesthesia provides cardioprotection in patients undergoing CABG. METHODS: Randomized, controlled trial enrolling 157 patients with preserved left ventricular function scheduled for elective or urgent on-pump CABG. Patients received either volatile- or propofol-based anaesthesia and postoperative sedation. Volatile sedation in the ICU was provided with the use of the AnaConDa® device (Sedana Medical, Uppsala, Sweden). The primary outcome was myocardial injury measured by serial troponin measurement at the beginning of surgery, 2, 4 and 12-16 h after ICU admission. The secondary outcome was cardiac performance expressed as cardiac index (CI) and the need for inotropic and vasopressor drug support. The peak postoperative troponin level was defined as the highest level at any time in the first 16 h after surgery. RESULTS: 127 patients completed the study protocol, 60 patients in the volatile group and 67 patients in the propofol group. Troponin levels were similar between groups at all of the measured time points. There were no differences in cardiac index or vasoactive drug support except for the immediate post- cardiopulmonary bypass (CPB) period when patients in the volatile group had low systemic vascular resistance, high CI and required more vasopressors. There was no difference in postoperative kidney function, intensive care unit discharge or hospital discharge time. CONCLUSIONS: The use of volatile-based anaesthesia and postoperative sedation did not confer any cardioprotection compared with propofol-based anaesthesia and sedation in patients who had good left ventricular function and were undergoing CABG.