[Ventilatory and hemodynamic effects of continuous positive airway pressure in dogs with acute cardiogenic pulmonary edema].

OBJECTIVE: To investigate the ventilatory and hemodynamic effects of continuous positive airway pressure (CPAP) in acute cardiogenic pulmonary edema (ACPE) in dogs. METHODS: Cardiac output (CO), heart rate (HR), blood pressure (BP), pulmonary artery wedge pressure (PAWP), central venous pressure (CVP) and intrathoracic negative pressure (Pt) were measured. These parameters were recorded at spontaneous breath, 5 cm H2O, 10 cm H2O, and 15 cm H2O CPAP in ten dogs before (healthy state) and after the induction of ACPE. RESULTS: When ACPE occurred, the dogs showed rapid breath, higher Pt [-(10.90 +/- 0.75) versus -(4.90 +/- 0.09) cm H2O], decreased CVP and CO [(10.1 +/- 0.4) versus (8.0 +/- 0.7) mm Hg and (1.52 +/- 0.13) versus (0.85 +/- 0.09) L/min, respectively], increased PAWP [(9.64 +/- 0.54) versus (17.77 +/- 0.79) mm Hg, all P < 0.05]. The correlation coefficient of the change of CVP and the change of Pt was 0.78 (P < 0.01). The addition of 5 or 10 cm H2O CPAP decreased Pt [-(6.53 +/- 0.11), -(5.14 +/- 0.25) cm H2O], which resulted in increased cardiac function. CO was also increased [(1.45 +/- 0.11), (1.24 +/- 0.11) L/min], with decreased PAWP [(15.80 +/- 0.55), (17.40 +/- 0.70) mm Hg; P < 0.05]. After the application of 15 cm H2O CPAP, Pt reached nearly zero [-(0.82 +/- 0.37) cm H2O], CO decreased to (0.82 +/- 0.07) L/min and PAWP increased to (19.23 +/- 0.73) mm Hg (P < 0.05). CONCLUSIONS: ACPE induced rapid breath, elevated Pt and decreased CVP and CO. Proper CPAP can improve CO by regulating Pt, hence the improvement of other hemodynamic parameters.

[A retrospective study on the treatment of patients with chronic obstructive pulmonary disease by face mask mechanical ventilation].

OBJECTIVE: To assess the effect and the influencing factors in face mask mechanical ventilation (FMMV) for the treatment of COPD with respiratory failure (RF), and to compare the efficacy and efficiency of FMMV with endotracheal intubation mechanical ventilation (ETMV). METHODS: From 1991 to 2001, 4 ventilating periods were named initial, middle, late, and extending stage according to ventilators, face masks and mechanical ventilating methods. The results of FMMV in the 4 periods were compared. The results in patients with FMMV who reached the endotracheal intubation criteria were also compared with those in ETMV ones from 1988 to 1990. RESULTS: 385 patients with COPD and RF were admitted to RICU. The proportion of FMMV in all MV patients increased [48% (11/23), 79% (15/19), 85% (29/34), 91% (223/246)]; at the same time the effective rate of FMMV [46% (5/11), 67% (10/15), 83% (24/29), 89% (198/223)] and the total effective rate [71% (35/49), 71% (20/28), 81% (34/42), 88% (234/266)] also increased. 83 percent of the patients who suffered from severe disturbances of consciousness in the late and extending stage were successfully weaned from FMMV. Complications including the rates of nasal bridge erosion [27% (3/11), 13% (2/15), 7% (2/29), 2% (4/223)] and the rates of stomach distension [46% (5/11), 40% (6/15), 21% (6/29), 5% (11/223)] all decreased. The ventilation times and length of stay were significantly shorter than those in patients with ETMV. The rate of nosocomial pneumonia and the mortality of inpatients were significantly lower. CONCLUSION: The ventilating techniques, ventilators and face masks were the main factors influencing FMMV results. FMMV could be used rationally for most COPD patients with RF as a valuable alternative to ETMV.