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Background The physicochemical properties of propofol could allow diffusion across the alveolocapillary membrane and a measurable degree of pulmonary propofol elimination. The authors tested this hypothesis and showed that propofol can be quantified in expiratory air and that propofol breath concentrations reflect blood concentrations. This could allow real-time monitoring of relative changes in the propofol concentration in arterial blood during total intravenous anesthesia. Methods The authors measured gas-phase propofol using a mass spectrometry system based on ion-molecule reactions coupled with quadrupole mass spectrometry which provides a highly sensitive method for on-line and off-line measurements of organic and inorganic compounds in gases. In a first sequence of experiments, the authors sampled blood from neurosurgery patients undergoing total intravenous anesthesia and performed propofol headspace determination above the blood sample using an auto-sampler connected to the mass spectrometry system. In a second set of experiments, the mass spectrometry system was connected directly to neurosurgery patients undergoing target-controlled infusion via a T piece inserted between the endotracheal tube and the Y connector of the anesthesia machine, and end-expiratory propofol concentrations were measured on-line. Results A close correlation between propofol whole blood concentration and propofol headspace was found (range of Pearson r, 0.846-0.957; P < 0.01; n = 6). End-expiratory propofol signals mirrored whole blood values with close intraindividual correlations between both parameters (range of Pearson r, 0.784-0.985; n = 11). Conclusion Ion-molecule reaction mass spectrometry may allow the continuous and noninvasive monitoring of expiratory propofol levels in patients undergoing general anesthesia.

Spontaneous pain, hyperalgesia as well as sensory abnormalities, autonomic, trophic, and motor disturbances are key features of Complex Regional Pain Syndrome (CRPS). This study was conceived to comprehensively characterize the interaction of these symptoms in 118 patients with chronic upper limb CRPS (duration of disease: 43±23 months). Disease-related stress, depression, and the degree of accompanying motor disability were likewise assessed. Stress and depression were measured by Posttraumatic Stress Symptoms Score and Center for Epidemiological Studies Depression Test. Motor disability of the affected hand was determined by Sequential Occupational Dexterity Assessment and Michigan Hand Questionnaire. Sensory changes were assessed by Quantitative Sensory Testing according to the standards of the German Research Network on Neuropathic Pain. Almost two-thirds of all patients exhibited spontaneous pain at rest. Hand force as well as hand motor function were found to be substantially impaired. Results of Quantitative Sensory Testing revealed a distinct pattern of generalized bilateral sensory loss and hyperalgesia, most prominently to blunt pressure. Patients reported substantial motor complaints confirmed by the objective motor disability testings. Interestingly, patients displayed clinically relevant levels of stress and depression. We conclude that chronic CRPS is characterized by a combination of ongoing pain, pain-related disability, stress and depression, potentially triggered by peripheral nerve/tissue damage and ensuing sensory loss. In order to consolidate the different dimensions of disturbances in chronic CRPS, we developed a model based on interaction analysis suggesting a complex hierarchical interaction of peripheral (injury/sensory loss) and central factors (pain/disability/stress/depression) predicting motor dysfunction and hyperalgesia.

Background— The risk of preoperative anemia in patients undergoing heart surgery has not been described precisely. Specifically, the impact of low hemoglobin per se or combined with other risk factors on postoperative outcome is unknown. Thus, we determined the effects of low preoperative hemoglobin and comorbidities on postoperative adverse outcomes in patients with coronary artery bypass graft in a large comprehensive multicenter study. Methods and Results— The Multicenter Study of Perioperative Ischemia investigated 5065 patients with coronary artery bypass graft at 70 institutions worldwide, collecting ≈7500 data points per patient. In 4804 patients who received no preoperative transfusions, we determined the association between lowest preoperative hemoglobin levels and in-hospital cardiac and noncardiac morbidity and mortality and the impact of concomitant risk factors, assessed by EuroSCORE, on this effect. In patients with EuroSCORE cerebral; P Conclusions— Anemic patients undergoing cardiac surgery have an increased risk of postoperative adverse events. Importantly, the extent of preexisting comorbidities substantially affects perioperative anemia tolerance. Therefore, preoperative risk assessment and subsequent therapeutic strategies, such as blood transfusion, should take into account both the individual level of preoperative hemoglobin and the extent of concomitant risk factors.

The persistent variability in red blood cell transfusion practice in coronary artery bypass graft (CABG) patients, despite established guidelines, suggests inappropriate use. Our objective was to determine the impact of postoperative red blood cell (RBC) transfusion in entirely stable CABG patients. We investigated a cohort of 940 stable CABG patients from the 5,065 patients enrolled in the Multicenter Study of Perioperative Ischemia Epidemiology II (EPI II) Study with (1) low to moderate risk profile; (2) postoperative hemoglobin levels ≥ 10 g/dL; (3) minimal postoperative blood loss, and (4) no evidence of any morbid event on the day of surgery. RBC transfusion was assessed during the first 24 postoperative hours and multiorgan outcomes as well as markers of resource utilization from postoperative day one to hospital discharge. Transfused patients (N =190, 20.2 %) were more likely to suffer myocardial infarction (OR, 1.89; 95 % CI, 1.08 to 3.29; P = 0.02); renal dysfunction (OR, 3.35; 95 % CI, 1.01 to 11.1; P = 0.04); renal failure requiring dialysis (OR, 4.01; 95 % CI, 0.99 to 16.2; P = 0.05); and/or harvest site wound infection (OR, 5.45; 95 % CI, 1.87 to 15.9; P = 0.001). RBC transfusion was shown to be an independent predictor of composite morbidity outcome, cardiac morbidity, and harvest site wound infection in multivariate analysis. In transfused patients, the mean duration of hospitalization was increased by 2.5 days (14.4 days vs. 11.9 days; P < 0.001). In CABG patients with low to moderate mortality risk profiles, adequate hemoglobin values and low bleeding rates, postoperative RBC transfusion is associated with an increased risk for cardiac, renal and infectious morbidity, as well as increased health care expenses, without any detectable benefit.