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 μg 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.

BACKGROUND: Noninvasive ventilation (NIV) is increasingly utilized outside the ICU for patients with acute respiratory failure. However, success and failure risk factors and patient safety aspects have been poorly explored in this setting. So far, no study has evaluated the perspective of the patient, despite the known high relevance of patient participation for NIV success. METHODS: We prospectively interviewed (following a standard questionnaire) the patients successfully treated with NIV for acute respiratory failure outside the ICU. Subjects were interviewed 24–48 hours after NIV suspension. Exclusion criteria: NIV failure, patient not competent, patient unwilling to participate in the study, patient transferred to the ICU. RESULTS: Forty-five consecutive patients were included in the study. Only 20% participated in the initial setting of NIV parameters. More than 40% reported they never had the possibility to discuss the NIV treatment. Eighty percent reported they were never asked to try another interface. All subjects knew how to call for help, but only one fourth had been trained to remove the mask, and 22% reported not being able at all to remove the mask if needed. One half of the subjects reported having received help immediately when needed, but 15% waited more than 3 min. All subjects reported complications, and 18% reported respiratory worsening while on NIV. CONCLUSIONS: Subjects reported a low level of involvement in the initial setting of NIV treatment, low satisfaction about communication with the caring staff, and a suboptimal safety level in case of emergency.