MILAN—Noninvasive pressure support ventilation (PSV) is effective in treating acute cardiogenic pulmonary edema (ACPE), but the long treatment duration assumed to be required has relegated noninvasive PSV to the ICU. An uncontrolled, prospective trial now demonstrates that a 90-minute trial of noninvasive PSV can obviate intubation and ICU admission in almost three quarters of ACPE patients who do not improve with oxygen and medical treatment in the emergency department.[1]

“This kind of treatment could be very useful in resolving … pulmonary insufficiency in ACPE,” said author Gaetano Iapichino, MD. “Because results were quite quickly obtained,” he noted, “we succeeded in reducing the number of patients admitted to the ICU.”

Noninvasive PSV and invasive mechanical ventilation are known to reduce respiratory workload and thus cardiac load in ACPE patients for whom medical treatment is insufficient. Because emergency departments are typically unequipped to deliver such forms of ventilation, these patients generally require ICU admission. Unfortunately, ICU resources are frequently overextended, said Dr. Iapichino, Director of the Institute of Anesthesiology and Critical Care at University of Milan. In an effort to minimize ICU admissions, he and colleagues tested short-term noninvasive PSV in the emergency department.

Full–face-mask PSV was administered to 54 ACPE patients who were unresponsive to medical therapy. Another four patients did not tolerate the mask and were transferred to an ICU. In the first phase of the study, noninvasive PSV was administered to 19 patients until efficacy was shown (ie, dyspnea resolved and both hemodynamic parameters and peripheral perfusion improved); a 15-minute weaning test was then conducted to establish whether the patients could breathe independently. After an interim analysis, the investigators limited the duration of noninvasive PSV to a maximum of 90 minutes before weaning in another 35 patients. Noninvasive PSV was administered for an average of 118 min and 77 min during the first and second study phases, respectively.

The condition of five of the 54 patients progressively worsened despite noninvasive PSV, and weaning attempts failed in another six; those patients were transferred to an ICU. Among the 43 successfully treated patients, noninvasive PSV enhanced hemodynamic and respiratory parameters: Arterial blood pH, oxygen and carbon dioxide tension, oxygen saturation, mean blood pressure, and heart rate improved significantly. Notably, these patients could be moved to medical wards rather than ICUs.

WHO SHOULD RECEIVE NONINVASIVE PSV?

Similar success rates (76% and 73%) in the two phases of the trial suggest that a 90-minute trial of noninvasive PSV is appropriate for many ACPE patients. However, odds of treatment failure were more than 10 times higher in patients with mean arterial blood pressure below 95 mm Hg than in other patients. Normal or low arterial pressures in these patients may reflect decreased left ventricular function and insufficient cardiac reserve, Dr. Iapichino explained. The presence of chronic obstructive pulmonary disease associated with ACPE also increased risk of requiring invasive ventilation (odds ratio, 9.4). Thus, for ACPE patients who are not candidates for a noninvasive PSV trial, “don’t lose time,” Dr. Iapichino stressed. “Go ahead with invasive mechanical ventilation.”

—Mimi Zucker, PhD

Reference
1. Giacomini M, Iapichino G, Cigada M, et al. Short-term noninvasive pressure support ventilation prevents ICU admittance in patients with acute cardiogenic pulmonary edema. Chest. 2003;123:2057-2061.

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