BackgroundIn the immediate postoperative period, obese patients are more likely to exhibit hypoxaemia due to atelectasis and impaired respiratory mechanics, changes which can be attenuated by non-invasive ventilation (NIV). The aim of the study was to evaluate the duration of any effects of early initiation of short term pressure support NIV vs. traditional oxygen delivery via venturi mask in obese patients during their stay in the PACU.MethodsAfter ethics committee approval and informed consent, we prospectively studied 60 obese patients (BMI 30-45) undergoing minor peripheral surgery. Half were randomly assigned to receive short term NIV during their PACU stay, while the others received routine treatment (supplemental oxygen via venturi mask). Premedication, general anaesthesia and respiratory settings were standardized. We measured arterial oxygen saturation by pulse oximetry and blood gas analysis on air breathing. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 1 h, 2 h, 6 h and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05.ResultsThere were no differences at the first assessment. During the PACU stay, pulmonary function in the NIV group was significantly better than in the controls (p < 0.0001). Blood gases and the alveolar to arterial oxygen partial pressure difference were also better (p < 0.03), but with the addition that overall improvements are of questionable clinical relevance. These effects persisted for at least 24 hours after surgery (p < 0.05).ConclusionEarly initiation of short term NIV during in the PACU promotes more rapid recovery of postoperative lung function and oxygenation in the obese. The effect lasted 24 hours after discontinuation of NIV. Patient selection is necessary in order to establish clinically relevant improvements.Trial Registration#DRKS00000751; http://www.germanctr.de

These results suggest that the integration of a pre-anesthesia assessment clinic in anesthetic patient care is not favorable from the patients' point of view because getting to know the anesthetist who will deliver anesthesia is of paramount importance to most patients. In cases where a pre-anesthetic assessment clinic is indispensable, other measures to build up confidence compensating for the lack of personal patient-physician relationship should be developed. In this respect, the promotion of a corporate identity of the whole anesthesia department may be beneficial. Furthermore, keeping the waiting time as short as possible should be a high priority as this item was rated the second most important factor.

SummaryObesity impairs peri-operative lung function. To evaluate the impact of pressure support ventilation vs pressure controlled ventilation in moderately obese adults upon early postoperative lung function, we randomly assigned 68 moderately obese patients (body mass index 25-35 kg.m )2 )undergoing minor surgery to receive intra-operative ventilation either with pressure support or pressure controlled ventilation. We performed intra-operative blood gas analysis and measured pulse oximetry saturation, spirometry values at pre-operative assessment (baseline) and at 10 min, 30 min, 2 h and 24 h after extubation. The intra-operative oxygenation index (arterial partial pressure of oxygen ⁄ fraction of inspired oxygen) in the pressure support ventilation group was significantly improved over time (p < 0.0001). Postoperatively, the pressure support ventilation group also had better lung function and oxygenation values than did the pressure controlled ventilation group (p < 0.005). We conclude that pressure support ventilation better maintains lung function than pressure controlled ventilation in moderately overweight patients scheduled for minor surgery.

Patient-controlled analgesia (PCA) is one of the well established methods for the treatment of postoperative pain. A cochrane-review concluded that PCA is associated with better postoperative pain ratings and improved patient-satifaction compared to traditional way of administering opioids. Some prerequisites concerning patient selection, education of the patient and the medical staff, and supervision during PCA therapy are mandatory for a safe use of PCA. Current PCA modalities (intravenous and epidural routes of application) are expanded by newer, less invasive routes of drug administration, e.g. by the iontophoretic transdermal and the sublingual route. Their role in improving safety and the quality of pain therapy on the one hand side, and costs on the other hand side are discussion.

Respiratory impairment is common after general anesthesia, largely due to a reduction of functional residual capacity resulting in ventilation/perfusion mismatch and atelectasis [1-3]. Obesity, increased age, and duration of surgery are major factors reinforcing the occurrence of atelectasis [4-6]. Compression atelectasis due to increased abdominal pressure in the supine position, more pronounced when using neuromuscular blocking agents, absorption atelectasis due increased inspired fraction of oxygen, hypoventilation and upper airway collapse also contribute [7-10]. Recruitment maneuver followed by PEEP proofed to be effective in increasing functional residual capacity and reducing atelectasis and pulmonary shunting [11]. Nevertheless atelectasis within the postoperative period is still common. Thus several other factors may have a predictive value in terms of postoperative respiratory impairment and atelectasis. Residual effects of neuromuscular blocking agents or hypnotics as well as duration of surgery are well known anesthesia and surgery related predictors for lung function impairment within the immediate postoperative period and patients related predictors are as follows age, BMI and gender [12]. We designed prospective, observational, blinded study to evaluate the impact of these factors and reveal possible interactions within a large study population. Methods Study population The study was approved by the Ethics Committee of the University of Marburg (Germany), and written consent was obtained. Between 2005 and 2009 we studied 397 patients with BMI between 25-40 (ASA II-III) undergoing minor surgery (Table 1/2). In order to minimize potential factors interfering with postoperative lung function measurements (e.g. increased postoperative pain sensations) patients