Noninvasive nasal mask ventilation beyond the ICU for an exacerbation of chronic respiratory insufficiency

Abstract

Study objective: To assess the usefulness of noninvasive nasal mask ventilation (NMV) in the treatment of an exacerbation of chronic respiratory insufficiency in patients stable enough to be admitted to a non-ICU ward.

Design: A prospective study in which the beneficial effect of NMV was compared with conservative treatment.

Setting: A ward of respiratory medicine of a tertiary-referral teaching hospital.

Patients: The study group included 15 patients with acute respiratory acidosis. These patients had pH less than 7.35 and PaCO2 more than 60 mm Hg, respiratory rate of 30 breaths or less per minute, hemodynamic stability, and alertness and willingness of cooperation with the NMV treatment. The control group consisted of 16 patients who fulfilled the same arterial blood gas requirements, retrospectively selected from the discharge forms of the ward of respiratory medicine for the year 1993.

Interventions: Patients underwent NMV for two sessions per day (one in the morning and one in the afternoon), each session lasting 4 h. A volumetric respirator (Monnal D; Taema; Paris, France) was used in four patients with restrictive disease. A positive-pressure ventilator (DP90; Taema; Paris, France) was used in 11 patients with obstructive disease. Control patients received standard medical, oxygen, and chest physical therapy.

Results: As compared with pre-NMV values, mean pH was significantly higher at 4 h of NMV after the patient's ventilatory adaptation (t = 8.814, p < 0.001) and at the end of NMV (t = 12.06, p < 0.001). Ventilatory support also produced a significant improvement in hypercapnia (pre-NMV vs NMV after the patient's ventilatory adaptation, t = 6.675, p < 0.001; pre-NMV vs post-NMV, t = 6.976, p < 0.001). Posttreatment pH and PaCO2 values were significantly higher and lower, respectively, in NMV-treated patients than in controls. At the end of treatment, a significantly higher PaO2/FIO2 ratio was documented in the study group than in controls (post-NMV vs posttreatment, t = 2.846, p < 0.01).

Conclusions: NMV associated with standard treatment may be more beneficial than conservative treatment alone for improving blood gas exchange in patients with chronic respiratory insufficiency admitted to the hospital (but not the ICU) for an episode of acute decompensation and respiratory acidosis.