Nocturnal negative pressure ventilation

In this study, 25 patients between the ages of 12 and 24 years who had neuromuscular diseases, a vital capacity less than 50 percent of predicted, and a history suggestive of nocturnal hypoventilation were observed with overnight monitoring of end-tidal CO2 (EtCO2) and O2 saturation (SaO2). Those patients with a strong clinical history and evidence of nocturnal hypoventilation (increased EtCO2 of 50 to 70 torr and decreased SaO2 [less than 90 percent]) (10 patients) were placed on nocturnal negative pressure ventilation (NNPV). Admission, treatment, and posttreatment arterial blood gases were analyzed by paired statistical "t" tests. Comparison of mean PaO2 values obtained on admission with those obtained during treatment revealed a greater than 97.5 percent confidence (p = 0.025; n = 7). Mean PaO2 values obtained after treatment (off negative pressure ventilation [NPV], awake during daytime) were 65.9 +/- 18.2 mmHg and 79.0 + 14.5 mmHg, respectively (p = 0.005; n = 6). Comparison of post-treatment PaO2 values as a percentage of admission (pretest) values showed a significant change at the 0.5 percent level with an applied Wilcoxan Signed-ranks Matched-pairs Test. The mean PaCO2 values obtained upon admission and those obtained during treatment were 53.7 +/- 15.1 mmHg and 48.1 +/- 14.2 mmHg, respectively (p = 0.05; n = 7), and comparison mean PaCO2 values obtained upon admission and after treatment were 57.9 +/- 16.0 mmHg and 51.2 +/- 7.0 mmHg, respectively (p = 0.1; n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)