[Clinical study of mechanical ventilation in acute cardiogenic pulmonary edema patients]

To study the application of mechanical ventilation in acute cardiogenic pulmonary edema (ACPE), and compare the changes in hemodynamics between continuous positive airway pressure proportional pressure support (CPAP-PPS) with continuous positive airway pressure-pressure support ventilation (CPAP-PSV).

Non-invasive and invasive ventilation were performed in 77 ACPE patients. At the initiation of invasive ventilation and the phase of low assist ventilation in 61 patients who were treated with mechanical ventilation longer than 24 hours, hemodynamics was monitored by partial CO(2) rebreathing method (non-invasive cardiac output, NICO) cardiopulmonary management system, and then compared the changes in the two kinds of ventilation under medicinal intervention.

Among 33 of 61 ACPE patients underwent non-invasive ventilation, 24 were successful, and the ratio was 72.7%. Among 33 patients with invasive ventilation (including 5 in whom ventilation was switched to non-invasive mode), 11 failed. Biphasic positive airway pressure/pressure support ventilation (BIPAP/PSV) was used in pressure controlled ventilation, with high pressure (Phigh) 16-24 cm H(2)O (1 cm H(2)O=0.098 kPa), time of high pressure (Thigh) 1.5 seconds, positive end expiratory pressure (PEEP) 6-15 cm H(2)O, fractional concentration of inspired oxygen (FiO(2)) 0.5, cardiac output (CO)/cardiac index (CI) was significantly improved compared with those of initial ventilation in successful ones in invasive group, and the improvement was more significant in PPS compared with PSV in low assist ventilation (all P<0.001). Those in whom invasive ventilation was failed had a low CI (<1.5 L.min(-1).m(-2)) even under drug intervention.

Hemodynamic monitoring should be performed when medicinal intervention and non-invasive/invasive ventilation are given to ACPE patients. Pressure controlled ventilation is recommended, and PEEP should be individualized (normally 6-15 cm H(2)O). Spontaneous ventilation should be restored as soon as possible, CPAP-PPS mode is practicable in patients in whom weaning of mechanical ventilation is difficult.