Transcatheter implantation of an aortic valve: anesthesiological management.

AIM: Transcatheter aortic valve implantation (TAVI) is an emergent alternative technique to surgery in high-risk patients with aortic stenosis. Here, we describe the anesthesiological management of patients undergoing TAVI at our institution over an 18-month period. METHODS: After a proper assessment of surgical risk and comorbidities, 69 patients underwent TAVI with the transfemoral/subclavian approach. Both Edwards-Sapien and Corevalve prostheses were implanted. The anesthetic regimen consisted of general anesthesia or local anesthesia plus sedation. RESULTS: Twenty-seven patients received general anesthesia, and 42 received local anesthesia plus sedation. Procedural complications included prosthesis embolization (2), ascending aorta dissection (1), ventricular fibrillation following rapid ventricular pacing (8), vascular access site complications (17), and the valve-in-valve procedure (1). Three patients had to be converted from local anesthesia to general anesthesia (one patient had refractory ventricular fibrillation, and two patients were restless). All patients were alive at the 30-day follow-up. Mechanical ventilation time was 8.5+/-0.03 h. Mean ICU stay was 20.1+/-2.89 h. Postoperative complications included acute renal dysfunction (11), advanced atrioventricular block (9), and stroke (1). Thirty-six out of 42 (86%) patients were alive at the 6-month follow-up. CONCLUSIONS: TAVI is feasible in high-risk patients who would not be able to undergo surgical valve replacement. Hemodynamic management is the main concern of intraoperative anesthesiological management. General or local anesthesia plus sedation are both valid alternative techniques that can be titrated according to patient characteristics. Close postoperative monitoring in the ICU is required.

Tricks and pitfalls regarding the hemodynamics of patients undergoing non-transplantation surgery for heart failure.

This paper aims to address the mechanisms responsible for poor perioperative cardiac performance, analyzing the pathophysiology of heart failure and the main hemodynamic parameters (contractility, preload, afterload, systemic vascular resistance, and pulmonary artery pressure) used in diagnosing patients and assessing their response to therapy. It will also discuss potential therapeutic approaches to cardiac surgery patients. With advances in monitoring and life support, our critically ill patients often become trapped in a sheer, impenetrable net of wires and tubes. Unfortunately, technology can seriously compromise patient safety if the data obtained is misinterpreted. While advanced technology has become a part of daily life in the Intensive Care Unit (ICU), there remains a crucial step that cannot be performed by computers: the link from sensors to patient status. We should always remember to look past the cables and monitors and to look at the patient. This would not only reduce the number of ever-present wires, but would also help improve patient outcome. The field of non-transplant cardiac surgery for heart failure is extremely challenging for the cardiac anesthesiologist. The high incidence of postoperative low cardiac output syndrome should mandate aggressive monitoring and therapy. Nevertheless, a comprehensive understanding of the pathophysiology of heart failure and the hemodynamic implications of surgical therapies is mandatory for optimal patient management. In particular, the presence of systolic dysfunction should not automatically rule out other potential causes of poor global cardiac performance.

Effect of morbid obesity on kinetic of desflurane: wash-in wash-out curves and recovery times.

AIM: The aim of this paper was to compare wash-in and wash-out curves of desflurane in morbidly obese and nonobese patients. METHODS: Fourteen patients (7 obese and 7 nonobese) were studied. In the nonobese patients, anaesthesia was started by administering 2 mg/kg propofol bolus and a target controlled effect site concentration of remifentanil set at 2.5 ng/mL. Obese patients were intubated using a flexible fiberoptic bronchoscopic technique facilitated by a target controlled effect site concentration of remifentanil set at 2.5 ng/mL. After endotracheal intubation, general anaesthesia was started by administering a 1.5 mg/kg propofol bolus dose. Ten minutes after induction of anaesthesia, 4% desflurane was administered for 30 min. Desflurane kinetics was determined by collecting end-tidal samples from first breaths at 1, 5, 10, 15, 20, 25 and 30 min. At last skin suture, the end-tidal concentration of desflurane was recorded from 5 consecutive breaths before their discontinuation, then the end-tidal samples of the inhalational agent were collected at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 min after terminating its administration. The period of time from discontinuation of desflurane to opening eyes, squeezing the observer's hand, extubation, stating the patients' name and providing date of birth was also recorded. RESULTS: The FA/FI ratio was higher in the nonobese group from the 10th to the 15th min. Wash-out curves of desflurane and recovery times were similar. CONCLUSION: Our results show that desflurane provides similar kinetic and recovery profiles in obese and nonobese patients.

Predictive performance of 'Servin's formula' during BIS-guided propofol-remifentanil target-controlled infusion in morbidly obese patients.

BACKGROUND: The aim of this study was to assess the predictive performance of 'Servin's formula' for bispectral index (BIS)-guided propofol-remifentanil target-controlled infusion (TCI) in morbidly obese patients. METHODS: Twenty patients (ASA physical status II-III, age 32-64 yr) undergoing bilio-intestinal bypass surgery, were recruited. Anaesthesia was induced by using a TCI of propofol with an initial target plasma concentration of 6 microg ml(-1), then adapted to maintain stable BIS values ranging between 40 and 50. A TCI of remifentanil was added to achieve pain control and haemodynamic stability. For propofol, weight was corrected as suggested by Servin and colleagues. With ideal body weight (IBW) corrected according to formula suggested by Lemmens and colleagues. For remifentanil, weight was corrected according to IBW. Arterial blood samples for the determination of blood propofol concentrations were collected at different surgical times. The predictive performance of propofol TCI was evaluated by examining performance accuracy. RESULTS: Median prediction error and median absolute prediction error were -32.6% (range -53.4%; -2.5%) and 33.1% (10.8%; 53.4%), respectively. Wobble median value was 5.9% (2.5%; 25.2%) while divergence median value was -1.5% h(-1) (-7.7; 33.8% h(-1)). CONCLUSION: Significant bias between predicted and measured plasma propofol concentrations was found while the low wobble values suggest that propofol TCI system is able to maintain stable drug concentrations over time. As already suggested before, a computer simulation confirmed that the TCI system performance could be significantly improved when total body weight is used.