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[Use of noninvasive mechanical ventilation to avoid intubation during acute respiratory insufficiency]
F Brijker1, F J van den Elshout, A de Rijk
1Afd. Longziekten: Ziekenhuis Rijnstate, Arnhem.
Objective:
To determine the value of noninvasive mechanical ventilation in patients with acute respiratory insufficiency.
Design:
Descriptive.
Methods:
Noninvasive mechanical ventilation was considered in all patients with acute respiratory insufficiency in the intensive care unit of the Rijnstate Hospital, Arnhem, the Netherlands, between 1 June 1998 and 31 January 1999. Indication for mechanical ventilation was: respiratory frequency > or = 28/min, and PaCO2 > 6.0 kPa, pH < 7.35, and/or PaO2 < 8.0 kPa. Patients were intubated immediately in case of systolic blood pressure < 90 mmHg, cardiac or respiratory arrest, coma or a severely diminished consciousness. The other patients received noninvasive mechanical ventilation by nasal or full face mask (pressure support: 10-20 cmH2O; positive end expiratory pressure (PEEP): 0-5 cmH2O). Patients were intubated if the respiratory frequency or the level of consciousness or a blood gas value deteriorated.
Results:
Of the 97 patients who needed ventilation support, 67 were immediately intubated. Noninvasive mechanical ventilation was administered in the other 30 (31%) patients, 22 men and 8 women with a mean age of 67 years (SD: 15). Causes for acute respiratory failure were: chronic obstructive pulmonary disease (COPD) (n = 12); pneumonia (n = 6); heart failure (n = 4); and other (n = 8). Median characteristics at baseline in the noninvasive mechanical ventilation group: acute physiology and chronic health evaluation (APACHE) II score: 17 (range: 1-25); respiratory frequency: 30/min (28-59); pH: 7.33 (6.99-7.54); PaCO2: 9.3 kPa (3.2-18.7); PaO2: 7.4 kPa (4.2-13.4); SaO2: 85% (63-95). Intubation was avoided in 9/30 (30%) of all patients and in 7/12 (58%) of the patients with COPD. Intubation was needed in 21/30 patients (70%): in 8/30 (27%) immediately because of clinical deterioration within 2 hours and in 13/30 (43%) after a mean period of stabilisation of 6 hours (2-16).
Conclusion:
Noninvasive mechanical ventilation prevented intubation in over half of the selected patients presenting with acute respiratory failure due to an exacerbation of COPD. The method appears to be less successful in acute respiratory failure due to other causes.