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Objective: Impaired tubular esophageal motility is involved in the pathogenesis of gastroesophageal reflux disease, which, in turn, has been shown to cause nosocomial pneumonia in critically ill patients. As multiple factors are involved, this pilot study was undertaken to evaluate whether, similarly, impaired esophageal motility may contribute to nosocomial infections by determining esophageal motility in critically ill patients undergoing mechanical ventilation and sedation in comparison to that of a healthy control group., Design: Open, single-centered study., Patients and Methods: Fifteen consecutive ventilated intensive care unit (ICU) patients with different diseases and three regimens of analgo-sedation were included: group 1: no analgo-sedation, group 2: ketamine and benzodiazepines, and group 3: fentanyl and benzodiazepines. Six healthy volunteers were studied as controls. Twenty-four hour esophageal anterograde (propulsive) and retrograde motility changes were assessed by a manometry system., Results: The frequencies of contractions were 0.67 +/- 0.1/min (no analgo-sedation) 0.093 +/- 0.02 (ketamine) and 0.076 +/- 0.01 (fentanyl) (p < 0.05 as compared to controls). The amplitudes (% of maximum) were 98 % (control), 58 % (analgo-sedation), 38 % (ketamine) and 42 % (fentanyl; p < 0.05 for the comparison of fentanyl and ketamine with controls). Whereas the percentage of propulsive contractions was significantly decreased in patients (no sedation: 45 %, ketamine: 34 %; fentanyl: 35 %, p < 0.05) as compared to controls (72 %), the percentage of retrograde contractions increased: no sedation: 29 %, ketamine: 34 % and fentanyl: 37 % as compared to controls: 10 %, p < 0.05. Analysis according to the underlying diseases showed marked inhibition of motility parameters within any disease group in comparison with controls., Conclusions: Irrespective of the underlying disease, propulsive motility of the esophageal body is significantly reduced during any kind of sedation in critically ill patients. Possibly central as well peripheral drug-related effects are involved in such a depression. Twenty-four hour motility recordings appear to be a valuable and feasible method to quantify and analyze esophageal motor disorders in critically ill patients.

Objective: It is well known that lung embolism is associated with an increase in pulmonary vascular resistance. Since the mechanisms of pulmonary vascular reactions during embolism are still unclear, the aim of this study was to investigate the potential involvement of endothelin-1 (ET-1) and thromboxane A2 (TXA2) as mediators of the pulmonary artery pressure (PAP) increase after embolism using the selective ETA receptor antagonist LU135252 [1], the ETB receptor antagonist BQ788 [2], and the cyclooxygenase inhibitor diclofenac., Design: Prospective experimental study in rabbits., Setting: Experimental laboratory in a university teaching hospital., Subjects: 36 adult rabbits of either sex., Interventions: The experiments were performed in 36 isolated and ventilated rabbit lungs which were perfused with a buffer solution containing 10% of autologous blood. Embolism was induced by the injection of 0.75 ml air into the pulmonary artery., Measurements and Results: PAP and lung weight, reflecting edema formation, were continuously recorded. Perfusate samples were drawn intermittently to determine TXA2 and ET-1 concentrations. Air injection resulted in an immediate increase in PAP up to 22.8 +/- 1.4 mm Hg at 2.5 min (control, n = 6), which was parallelled by an enhanced generation of TXA2. No relevant edema formation occurred during the observation period. Pretreatment with the ETA receptor antagonist LU135252 significantly reduced the pressure reaction after air embolism (p < 0.001) whereas the ETB receptor antagonist BQ788 (n = 6) was without marked effects. The administration of diclofenac (n = 6) did not alter the PAP increase 2.5 min after embolism, but significantly reduced the pressure reaction during the further observation period (p < 0.001). The application of LU135252 and diclofenac together (n = 6) also significantly reduced the PAP increase from 2.5 min during the total observation period (p < 0.001)., Conclusions: The acute pressure reaction after air embolism is mainly mediated via ET-1 by an ETA receptor related mechanism. TXA2 seems to maintain this reaction for a longer time.

Objective: Of the animal models of human hemorrhagic shock, the volume-controlled hemorrhage model appears to come closer to the clinical situation than the commonly used pressure-controlled model, since the volume-controlled model allows regulatory adjustment of blood pressure. The effects of volume-controlled hemorrhage on local cerebral blood flow (LCBF) of conscious animals are not known. The present study investigates specific reaction patterns of LCBF in comparison to mean cerebral blood flow (CBF) during graded volume-controlled hemorrhagic shock in conscious rats., Methods: Conscious, spontaneously breathing, and minimally restrained rats were subjected to different degrees of volume-controlled hemorrhage (taking either 25, 30, 35, or 40 ml arterial blood/kg body weight (b.w.). Thirty minutes after the completion of blood taking, LCBF was determined during hemorrhagic hypovolemia using the autoradiographic iodo (14C) antipyrine method. A group of untreated rats (no hemorrhage) served as controls. LCBF was determined in 34 defined brain structures and mean CBF was calculated., Results: During less severe hemorrhage (25 and 30 ml/kg b.w.) mean CBF was significantly higher than in the control group (+19% and +25%). During severe hemorrhage (35 and 40 ml/kg b.w.) mean CBF remained unchanged compared to the control values, although significant increases in LCBF could be detected in many of the brain structures analyzed (maximum +44%). The mean coefficient of variation of CBF was increased, indicating a larger heterogeneity of LCBF values at shed blood volumes of 35 and 40 ml/kg b.w., Conclusions: A comprehensive and novel description of the local distribution of CBF during graded volume-controlled hemorrhage in conscious rats shows unexpected increases in LCBF and mean CBF. This "hypovolemic cerebral hyperemia" might be caused by endogenous hemodilution, thus maintaining the blood supply to the brain during hypovolemic shock.

Objective: Purpose of the study was to investigate the potential influence of norepinephrine (NE) on immune functions in terms of systemic and organ-specific bacterial clearance in rabbits., Design: To enable quantification of the clearance process, defined numbers of exogenous Escherichia coli (1.3 x 10(8) CFU) were injected intravenously 60 min after starting the NE infusion at a low dose (1 microgram/kg per min, n = 6), causing an increase (30 mmHg) in mean arterial pressure without affecting the oxygen uptake, and at a higher dose (7.5 micrograms/kg per min, n = 6), resulting in a marked decrease (20%) in oxygen uptake, after infusion of NaCl solution (control, n = 6). In additional experiments (n = 6) NE (1 microgram/kg per min) was tested in endotoxemia induced by simultaneous infusion of endotoxin (40 micrograms/kg per h). Parameters monitored were arterial pressure, oxygen uptake, and rates of bacterial elimination from the blood. At 180 min after E. coli injection, the animals were sacrificed, and tissue samples of liver, kidney, spleen, and lung were collected for bacterial counts., Results: NE infusion resulted in a dose-dependent prolonged elimination of the injected E. coli from the blood and in significantly higher (p < 0.05) numbers of CFU in liver and lung compared to the controls. Significant impairment of bacterial clearance was found after shock-producing endotoxemia, whereas simultaneous infusion of NE and endotoxin caused only a slightly delayed blood clearance of the injected bacteria., Conclusion: NE dose dependently affected bacterial clearance, which might be due to ischemia-derived hypoxic impairment of the phagocytosis and lysis function of the reticuloendothelial system, whereas NE improved elimination of bacteria in a state of endotoxic shock.

Objective: To assess the effects of the cyclooxygenase inhibitor diclofenac in a canine model of pulmonary occlusion and reperfusion of the left lower lobe (LLL)., Design: Twelve adult beagle dogs (13-17 kg) were randomly assigned to a control group (n = 6) and a diclofenac-treated group (n = 6). Animals in the treatment group received 20 mg diclofenac sodium/kg as a single dose both before the experiment and at the end of surgical preparation; six animals served as controls., Interventions: In the anesthetized animals, the left upper and middle lobes were resected. Circulation and ventilation of the LLL were selectively blocked by clamping. Complete occlusion of the LLL (30 min) was followed by periods of selective reperfusion (10 min, RP) and combined reperfusion and reventilation (120 min, RP/RV)., Measurements and Results: Reperfusion of the LLL resulted in a significant increase in pulmonary arterial pressure (Ppa) in the early RP/RV period as compared to baseline values (25.3 +/- 4.7 vs 15.8 +/- 1.9 mmHg, p < 0.05, paired t-test). This increase was significantly inhibited in the diclofenac-treated animals (17.0 +/- 2.0 mmHg, p < 0.01 vs controls, ANOVA). Gravimetrically determined extravascular lung water (EVLW) showed no significant difference in the continuously ventilated lobes of the right lung between diclofenac-treated animals (3.8 ml/g dry weight) and controls (3.9 +/- 0.9 ml/g dry weight) at the end of the experiment. EVLW, however, increased significantly in the LLL of control animals after 2 h of combined reperfusion and reventilation, whereas this increase was significantly inhibited in the diclofenac-treated animals (4.5 +/- 0.7 ml/g dry weight in the diclofenac group vs 6.5 +/- 1.3 ml/g dry weight in the control group, p < 0.05)., Conclusions: Diclofenac inhibits the increase in both pulmonary arterial pressure and EVLW during reperfusion and reventilation of LLL. Thus, these changes appear to be mediated by cyclooxygenase metabolites.