Respiratory drive can be evaluated by airway occlusion pressure or hypercapnic ventilatory response .
To date, no previous clinical study has evaluated respiratory drive measured by a hypercapnic ventilatory response in patients with PMV.
There was also no significant difference in respiratory function between the two groups except hypercapnic ventilatory response (Table 2).
The hypercapnic ventilatory response ([mathematical expression not reproducible]) was 0.40 L/min/mmHg [+ or -] 0.16 L/min/mmHg in the weaning-success group compared with 0.28 L/min/mmHg [+ or -] 0.12 L/min/mmHg in the weaning-failure group (P = .036) (Figure 2).
We called this ratio the hypercapnic ventilatory response. 4) The ratio of the change in [P.sub.0.1] to baseline [P.sub.a]C[O.sub.2] ([delta][P.sub.0.1]/[P.sub.a]C[O.sub.2]).
Weaning failure patients had lower increases in [P.sub.0.1] and [V.sub.E] to hypercapnia (Figure 1) and lower hypercapnic respiratory drive response and hypercapnic ventilatory response value than successfully weaned COPD patients (Table 2).
The threshold values for each index with the fewest false classification were: baseline [P.sub.a]C[O.sub.2] 55 mmHg, hypercapnia test [P.sub.a]C[O.sub.2] 73 mmHg, hypercapnic respiratory drive response 0.20 cm[H.sub.2]O/mmHg, hypercapnic ventilatory response 0.30 l/min/mmHg, [delta][P.sub.0.1]/[P.sub.a]C[O.sub.2] 0.08 cm[H.sub.2]O/mmHg and [delta][V.sub.E]/[P.sub.a]C[O.sub.2] 0.08 l/min/mmHg.
Fourteen out of 15 patients (93.3%) with hypercapnic respiratory drive response and hypercapnic ventilatory response lower than the threshold value failed the weaning process, whereas 18 of 29 patients (62.1%) with hypercapnic drive response or hypercapnic ventilatory response, or both, higher than the threshold value, were successfully weaned (odds ratio 22.9 (confidence interval 95%: 2.6 to 199); P <0.001).
The setpoint for [PaCO.sup.2] is higher during sleep than wakefulness, and the hypercapnic ventilatory response
curve is shifted to the right throughout all stages of sleep as compared with wakefulness.
(2) Tibetans have greater hypoxic and hypercapnic ventilatory responses
, larger lungs, better lung functions and greater lung diffusing capacities than low landers.
In control of breathing, controller gain refers to the chemoresponsiveness of the system [i.e., chemosensitivity (hypoxic and hypercapnic ventilatory responses
) plus responsiveness] (121).
We have shown abnormalities in both awake hypoxic and hypercapnic ventilatory responses
in the methadone patients that would lead to this instability," Dr.