Doppler study of the effects of inhaled nitric oxide and intravenous almitrine on regional pulmonary blood flows in patients with acute lung injury.

BACKGROUND: Lung ultrasound can be used at bedside to assess initial lung morphology in hypoxemic patients. We hypothesized that blood flow in consolidated lung and therefore effects of inhaled nitric oxide (iNO) and intravenous almitrine could be directly assessed using Doppler transesophageal echocardiography (TEE). METHODS: We conducted a prospective study including 13 ALI patients with consolidated left lower lobe (LLL). Regional arterial and venous flow signals within the consolidation were recorded with TEE using Doppler at baseline, after iNO (5 ppm), almitrine (4 µg/kg/min) and their combination. Pulmonary shunt (Qs/Qt) was measured using a Swan-Ganz catheter. Arterial and venous velocity time integral (VTI), peak velocity (Vmax) and mean velocity (Vmean) were measured. Patients were responders if PaO2 basal value increased by 20% after iNO or almitrine. RESULTS: In 7 NO responders, iNO decreased regional arterial VTI (8.1±1.9 vs. 6.7±1.6, P<0.05). In 8 almitrine responders, almitrine decreased regional arterial and venous VTI (from 6.7±2.0 to 4.5±2.3 cm and from 12.3±5.4 to 7.5±3.8 cm, respectively, P<0.05). For all patients, combination of iNO and almitrine decreased regional arterial and venous VTI (from 7.3±0.3 to 4.1±0.3 cm and from 12.6±0.7 to 6.7±0.8 cm, respectively, P<0.05). Arterial and venous Vmean and Vmax significantly decreased. Variations of arterial VTI and venous Vmean were correlated to variations of Qs/Qt (r=.71, P<.001 and r=.62, P<.01, respectively). CONCLUSION: Doppler of consolidated LLL allows assessment of regional pulmonary circulation in ICU settings. It detects changes in flow profiles resulting from the administration of NO and/or almitrine. Further applicability remains to be determined.

Minimum alveolar concentration of halogenated volatile anaesthetics in left ventricular hypertrophy and congestive heart failure in rats.

BACKGROUND: Although many physiological and pathological conditions affect minimal alveolar concentration (MAC), there are no reliable data on the MAC for halogenated anaesthetics during left ventricular hypertrophy (LVH) and congestive heart failure (CHF). The aim of this experimental study was to determine the MAC values of halothane, isoflurane, and sevoflurane in rats, at early and later stages of cardiomyopathic hypertrophy. METHODS: LVH was induced by ascending aortic stenosis in 3-4-week-old rats. LVH and CHF in each animal were assessed weekly by echocardiography. MAC of halothane, isoflurane, and sevoflurane was determined using the tail-clamp technique in spontaneously breathing rats from each group. Response vs no-response data were analysed using logistic regression analysis. Data are medians (95% confidence interval). RESULTS: The MAC of halothane [1.30% (1.26-1.34)], isoflurane [1.52% (1.48-1.57)], and sevoflurane [2.93% (2.78-3.07)] in rats with LVH was not different from sham-operated rats [respectively, 1.23% (1.20-1.26), 1.52% (1.47-1.56), and 2.90% (2.79-3.00)]. Conversely, the MAC of halothane [1.44 (1.39-1.50)] and isoflurane [1.74 (1.69-1.78)], but not sevoflurane [2.99 (2.93-3.06)], was significantly increased in rats with CHF. CONCLUSIONS: MAC values for halothane, isoflurane, and sevoflurane were unchanged in rats with pressure-induced overload LVH. Conversely, the MAC for halothane and isoflurane, but not sevoflurane, was significantly increased in rats with CHF.