NPPV in Acute Lung Injury?

Abstract & Commentary

Synopsis: Although six of 12 patients with acute lung injury or acute respiratory distress syndrome were successfully managed with noninvasive ventilatory support in this case series, broad application of these results in other practice settings may be inappropriate.

Source: Rocker GM, et al. Chest 1999;115:173-177.

This paper describes the use of noninvasive positive-pressure ventilation (NPPV) in an anecdotal series of 12 episodes of ventilatory support in 10 patients with acute hypoxemic respiratory failure. NPPV was delivered via full-face mask using a Puritan Bennett 7200a ventilator in the pressure support mode. The patients were managed in the intensive care unit (ICU) of a tertiary referral center and university hospital in Nova Scotia, Canada.

The patients ranged in age from 25 to 89 years, and all were hemodynamically stable. Eight of 10 patients had medical disease (aspiration, bacteremia, fungemia, malaria, fat emboli, post-bone-marrow transplant, thrombotic thrombocytopenic purpura, and near-drowning); the other two patients had trauma (not otherwise specified) and burns with inhalation injury, respectively. APACHE II scores for the 10 patients averaged 16 (range, 11-29); their PaO2/FIO2 ratios prior to NPPV ranged from 50-277 mmHg (mean, 102). Two patients had two episodes of NPPV each. Rocker and colleagues state the European-American diagnostic criteria for acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS), although on two occasions only two thoracic quadrants were involved radiographically. Three patients died.

On nine occasions NPPV was used as the initial method of ventilatory assistance, and in six of these instances intubation was not required. NPPV was applied following planned (1) or unplanned (2) extubation in the other instances, and was unsuccessful in each case. Thus, NPPV was successful in six of 12 attempts in these patients. Rocker et al conclude that this is "a surprisingly high success rate" and recommend that this approach to ventilatory support "be considered for patients in stable condition in the early phase of ALI/ARDS."

COMMENT BY DAVID J. PIERSON, MD, FACP, FCCP

NPPV is now the standard of care for acute ventilatory failure due to exacerbations of chronic obstructive pulmonary disease (COPD), and it has also achieved good success in acute-on-chronic ventilatory insufficiency among patients with kyphoscoliosis and other neuromuscular or musculoskeletal disorders in which upper airway function is preserved. Similarly, both NPPV and continuous positive airway pressure (CPAP) have been found to be effective in avoiding invasive mechanical ventilation in patients with congestive heart failure with acute pulmonary edema. However, although there are anecdotal reports of the successful use of NPPV in acute severe asthma, these reports have been viewed skeptically by experienced clinicians and NPPV has seen little use in that setting.

This report suggests that NPPV may also have a role in managing patients with ALI/ARDS. I would take that conclusion with more than a few grains of salt, not because I doubt the veracity of Rocker et al’s report, but because of concerns about the generalizability of this small experience in a specific patient population.

In the county hospital and level 1 trauma center in which I practice, approximately 100 patients meet the European-American diagnostic criteria for ARDS each year. Half of these patients have multiple trauma, and half of the rest have nontraumatic surgical disease. Of the nonsurgical patients who develop ARDS, most have severe sepsis, overwhelming pneumonia, or drug overdose as their predisposition to the syndrome. In a practice environment with an aggressive prehospital rescue and transport system, most such patients are intubated in the field, in the emergency room, or in the operating room prior to arrival in the ICU. In my practice setting then, opportunities to manage patients with ALI/ARDS noninvasively are infrequent.

Although I believe it is important to place reported experiences such as those in this paper in the proper context of one’s own practice, I also agree that there are some patients in whom an attempt at NPPV would seem reasonable. As Rocker et al state, these would be patients with single-organ failure, who are hemodynamically stable, and in whom the duration of ventilatory support can be expected to be fairly brief. Such patients should be managed in an ICU setting, where appropriate monitoring can be carried out and the transition to invasive mechanical ventilation can be made promptly and safely if need be.

Noninvasive positive-pressure ventilation is the ventilatory support approach of choice in which of the following settings?

a. Status asthmaticus

b. Acute lung injury/acute respiratory distress syndrome

c. Acute ventilatory failure in chronic obstructive pulmonary disease

d. All of the above

e. None of the above