Lower versus higher hemoglobin threshold for transfusion in septic shock.

BACKGROUND: Blood transfusions are frequently given to patients with septic shock. However, the benefits and harms of different hemoglobin thresholds for transfusion have not been established. METHODS: In this multicenter, parallel-group trial, we randomly assigned patients in the intensive care unit (ICU) who had septic shock and a hemoglobin concentration of 9 g per deciliter or less to receive 1 unit of leukoreduced red cells when the hemoglobin level was 7 g per deciliter or less (lower threshold) or when the level was 9 g per deciliter or less (higher threshold) during the ICU stay. The primary outcome measure was death by 90 days after randomization. RESULTS: We analyzed data from 998 of 1005 patients (99.3%) who underwent randomization. The two intervention groups had similar baseline characteristics. In the ICU, the lower-threshold group received a median of 1 unit of blood (interquartile range, 0 to 3) and the higher-threshold group received a median of 4 units (interquartile range, 2 to 7). At 90 days after randomization, 216 of 502 patients (43.0%) assigned to the lower-threshold group, as compared with 223 of 496 (45.0%) assigned to the higher-threshold group, had died (relative risk, 0.94; 95% confidence interval, 0.78 to 1.09; P=0.44). The results were similar in analyses adjusted for risk factors at baseline and in analyses of the per-protocol populations. The numbers of patients who had ischemic events, who had severe adverse reactions, and who required life support were similar in the two intervention groups. CONCLUSIONS: Among patients with septic shock, mortality at 90 days and rates of ischemic events and use of life support were similar among those assigned to blood transfusion at a higher hemoglobin threshold and those assigned to blood transfusion at a lower threshold; the latter group received fewer transfusions. (Funded by the Danish Strategic Research Council and others; TRISS ClinicalTrials.gov number, NCT01485315.).

Hemodynamic perturbations during robot-assisted laparoscopic radical prostatectomy in 45° Trendelenburg position.

BACKGROUND: Robot-assisted laparoscopic radical prostatectomy has gained widespread use. However, circulatory effects in patients subjected to an extreme Trendelenburg position (45°) are not well characterized. METHODS: We studied 16 patients (ASA physical status I-II) with a mean age of 59 years scheduled for robot-assisted laparoscopic radical prostatectomy (45° head-down tilt, with an intraabdominal pressure of 11-12 mm Hg). Hemodynamics, echocardiography, gas exchange, and ventilation-perfusion distribution were investigated before and during pneumoperitoneum, in the Trendelenburg position and, in 8 of the patients, also after the conclusion of surgery. RESULTS: In the 45° Trendelenburg position, central venous pressure increased almost 3-fold compared with the initial value, with an associated 2-fold increase in mean pulmonary artery pressure and pulmonary capillary wedge pressure (P<0.01). Mean arterial blood pressure increased by 35%. Heart rate, stroke volume, cardiac output, and mixed venous oxygen saturation were unaffected during surgery, as were echocardiographic heart dimensions. After induction of anesthesia, isovolumic relaxation time was prolonged, with no further change during the study. Deceleration time was normal and stable. In the horizontal position after pneumoperitoneum exsufflation, filling pressures and mean arterial blood pressure returned to baseline levels. Pneumoperitoneum reduced lung compliance by 40% (P<0.01). Addition of the Trendelenburg position caused a further decrease (P<0.05). Arterial blood acid-base balance was normal. End-tidal carbon dioxide tension increased whereas arterial carbon dioxide was unaffected with unchanged ventilation settings. Pneumoperitoneum increased PaO2 (P<0.05). Ventilation-perfusion distribution, shunt, and dead space were unaltered during the study. CONCLUSIONS: Pneumoperitoneum and 45° Trendelenburg position caused 2- to 3-fold increases in filling pressures, without effects on cardiac performance. Filling pressures were normalized immediately after surgery. Lung compliance was halved. Gas exchange was unaffected. No perioperative cardiovascular complications occurred.

Effect of carbon dioxide pneumoperitoneum on development of atelectasis during anesthesia, examined by spiral computed tomography.

BACKGROUND: Anesthesia per se results in atelectasis development in the dependent regions of the lungs. The effect of pneumoperitoneum on atelectasis formation is not known. The aim of the current study was to measure by spiral computed tomography the effect of carbon dioxide pneumoperitoneum for laparoscopic surgery on the development of atelectasis, overall lung volume, and regional tissue volumes of gas and tissue. METHODS: Seven patients (American Society of Anesthesiologists physical status I), scheduled to undergo laparoscopic cholecystectomy, were observed. After induction of anesthesia, the patients were mechanically ventilated and positioned supine on the computed tomography table. Tomography of the lungs (10 mm spiral) was performed before and 10 min after induction of carbon dioxide pneumoperitoneum at an intraabdominal pressure of 11-13 mmHg. The Student t test was used for statistical analysis. A P value less than 0.05 was considered significant. RESULTS: Induction of pneumoperitoneum increased the mean atelectasis volume in the dependent lung regions by 66% (range, 11-170%). The overall lung volume and gas as well as tissue volume significantly decreased. Relative to the total lung volume, lung tissue volume increased, while gas volume decreased significantly. Both upper and lower lobes reacted the same way. A cranial displacement of the diaphragm between 1 and 3 cm (mean, 1.9 cm) was registered. CONCLUSION: Pneumoperitoneum at an intraabdominal pressure level of 11-13 mmHg increased the volume of atelectasis. Because lung tissue volume increased in the lung, there may have been an opening of previously closed vessels, which could explain previously seen increase in arterial oxygenation after induction of pneumoperitoneum.