Chest
Clinical Investigations in Critical CareNasal Positive Pressure Ventilation in Patients with Acute Respiratory Failure: Difficult and Time-Consuming Procedure for Nurses
Section snippets
Patients
Six consecutive patients were prospectively studied. A patient was eligible for this study when he was considered by the clinical team in charge as needing urgent intubation and mechanical ventilation but, for any reason, intubation was refused or deemed to be detrimental or hazardous (see individual case reports for details and indications for intubation). The duration of this study was 12 months (ie, between Feb 3, 1989, and Jan 5, 1990). During the same period, we intubated and ventilated a
CASE 1
This 49-year-old male patient had suffered from severe coronary artery disease for 15 years (two myocardial infarctions, followed by two coronary artery bypass grafts) when he received a heart transplant in 1987 because of left ventricular failure and persistent angina. Two years later, in the context of a cytomegalovirus infection probably induced by his immunosuppressive therapy (cyclosporine A, azathioprine, and prednisone), the patient developed neurologic symptoms; 15 days before admission
TECHNIQUES
For NPPV, we used respirators specifically designed for chronic domiciliary nocturnal ventilation, a technique with which we are accustomed (ie, Bennett Companion 2000, Kontron ABT 4100, or Draeger EV 800). All of these ventilators were used in the same way: assist-control mode; without PEEP; and breathing frequency, tidal volume, inspiratory:expiratory time ratio, and “trigger” function chosen according to the patient's comfort and arterial blood gas levels, after trial-and-error assays. The
RESULTS
Considered as a group, all six patients suffered from severe respiratory impairment (mean FEV1 <1 L) and acute-on-chronic respiratory acidosis (mean PaCO2, 9.8 kPa [74 mm Hg]) with a marked gas exchange abnormality (mean P[A-a]O2, 11 kPa [82 mm Hg]) (Table 2). In all patients, it was possible to lower the PaCO2 to some extent by using NPPV and to reverse the trend of steadily increasing hypercapnia; PaCO2 decreased by 33±13 percent (Fig 2), and there was a significant difference between the PaCO
DISCUSSION
Several elements of information can be derived from our study. First, nppv is feasible in acute respiratory failure, when only the possibility of lowering an increased PaCO2 is considered; however, in some patients, particularly the obstructive group, intubation appears to be ultimately unavoidable. It is unlikely that this technique will be considered as a way to buy time before intubation in such patients; endotracheal intubation is widely available, safe, and very often technically easy,1
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Manuscript received November 14; revision accepted April 8.