Yuichi Yatsu

Evaluation of density area in dorsal lung region during prone position using transesophageal echocardiography

ObjectiveTo evaluate the changes of density area in the dorsal lung regions of acute respiratory distress syndrome patients during prone position using transesophageal echocardiography. DesignRetrospective clinical study. SettingGeneral intensive care unit in a university hospital. PatientsTen patients with acute respiratory distress syndrome who underwent prone position therapy. InterventionsDensity areas in the left dorsal lung region were observed using transesophageal echocardiography before and after patients were in the prone position for 2 hrs. In five patients, a pediatric transesophageal echocardiography probe was left in the esophagus and used for observation during the prone procedure. Measurements and Main ResultsChanges of density area and Pao2/Fio2 were observed. The density areas decreased after prone position compared with those of preprone position (preprone 11.4 ± 5.1 cm2, after prone 5.6 ± 3.5 cm2, mean ± sd, p < .01, respectively). There was also a significant correlation between the percentage change of density area and Pao2/Fio2 (r = .47, p < .05) after prone position. During prone position, the density area decreased; however, there was no correlation between the percent changes of density area and Pao2/Fio2. ConclusionIt was possible to observe the change in density area during prone position using transesophageal echocardiography. The change of density area estimated with transesophageal echocardiography during prone position was useful to estimate the effectiveness of the procedure.

Exposure to Cigarette Smoke Impairs Alveolar Macrophage Functions during Halothane and Isoflurane Anesthesia in Rats

BACKGROUND Smoking alters numerous alveolar macrophage functions and is an important risk factor for postoperative pulmonary complications. The authors therefore tested the hypothesis that smoke exposure impairs antimicrobial and proinflammatory responses in alveolar macrophages during halothane and isoflurane anesthesia with mechanical ventilation. METHODS Thirty control rats and 30 rats exposed to cigarette smoke were mechanically ventilated with 1.5 minimum alveolar concentration halothane and isoflurane. Ten smoke-exposed and control animals were assigned to one of three different anesthetic durations (0, 2, and 6 h). The fraction of aggregated cells and cell distribution were determined. Opsonized and unopsonized phagocytosis was measured. Microbicidal activity was determined as the ability to kill Listeria monocytogenes. The expression of interleukin (IL)-1alpha, IL-1beta, IL-6, macrophage inflammatory protein-2, interferon-gamma, and tumor necrosis factor-alpha was measured by semiquantitative reverse-transcription polymerase chain reaction. Pulmonary lavage concentrations of these cytokines were measured by enzyme-linked immunosorbent assay. RESULTS During both halothane and isoflurane anesthesia, the fraction of aggregated macrophages increased, whereas unopsonized and opsonized phagocytosis and microbicidal activity decreased significantly over time in both groups. Responses observed in smoke-exposed rats were almost twice as great as those observed in the control rats. Gene expression and production of all proinflammatory cytokines except IL-6 increased 2-20-fold during anesthesia. The increases in IL-1beta, interferon-gamma, and tumor necrosis factor-alpha in the control rats were 1.5-8 times greater than those in the smoke-exposed rats. CONCLUSION Antimicrobial and proinflammatory responses of alveolar macrophages during anesthesia were markedly suppressed by smoke exposure. Our data suggest that smoke exposure reduces the efficacy of immune defenses during anesthesia.

A New Method to Estimate Regional Pulmonary Blood Flow Using Transesophageal Echocardiography

BACKGROUND:We report a novel method to estimate regional blood flow in the atelectatic lung using transesophageal echocardiography in an experimental dog model. To verify the efficacy of the method, we investigated the ability of this experimental model to detect changes in regional pulmonary blood flow. METHODS:Fourteen anesthetized and ventilated mongrel dogs were randomized into an isoproterenol group (n = 7) or a dopamine group (n = 7). To produce an atelectatic lesion, 60 mL/kg of saline was infused into the left pleural space. The velocity time integral (VTI) derived from pulse Doppler was evaluated as an index of blood flow in the atelectatic lesion. To investigate the response of the method to changes in blood flow, the VTI and the shunt fraction (Qs/Qt) were measured during systemic administration of isoproterenol 0.05 &mgr;g · kg−1 · min−1 (as a pulmonary vasodilator) and dopamine 10 &mgr;g · kg−1 · min−1 (as a pulmonary vasoconstrictor). RESULTS:Both VTI and Qs/Qt were increased significantly by isoproterenol administration. There was a significant correlation between the percentage changes of VTI and Qs/Qt with isoproterenol administration (r2 = 0.50, P < 0.001). Both VTI and Qs/Qt were unchanged during administration of dopamine. CONCLUSIONS:Transesophageal echocardiography may be useful in detecting changes in regional pulmonary blood flow in an atelectatic lesion.