Table 1—

Ventilation settings, arterial blood gases and number of studies performed, classified by clinical situation

	Acute setting: ARF	At the start of long-term ventilation: CRF	At steady state: LTMV	p-value
Age yrs	69.5±16	60, 8±18*	65.6±16
BMI kg·cm⁻²	29.2±9	29.7±10	32.2±11	ns
FEV₁ L·s⁻¹	0.97±0.68^§	1.15±0.6*	1.09±0.53
FEV₁ % pred	40.9±19.7	45.3±17	45.5±18
FVC L	1.56±0.77^§	1.51±0.74	1.61±0.75	ns
FVC % pred	51.4±17	49.3±20	53.1±19
Mask type nasal/facial^#	36/33	41/12*	90/10*^,ƒ
IPAP cmH₂O	16.6±1.9	16.6±2.0	17.0±2.1	ns
EPAP cmH₂O	5.2±1.8	5.4±2.2	5.6±2.3	ns
Backup respiratory rate	14.5±1.10	14.0±1.5	14.1±1.3	ns
P_a,O₂ mmHg^¶,+	61.3±12.8	65.3±11.6	66.1±10.7*
P_a,CO₂ mmHg^¶,+	68.6±13.8	55.9±9.3*	44.8±8.3*^,ƒ
pH^¶,+	7.32±6.0	7.37±3.5*	7.40±2.8*^,ƒ
Number of traces per clinical situation	2.6±1.7	2.7±1.5	1.70±0.9*^,ƒ
Number of polygraphys/clinical situation	19/69	9/53^##	7/100*^,ƒ

Data are presented as mean±sd or n/n. ARF: acute respiratory failure; CRF: chronic respiratory failure; LTMV: long-term mechanical ventilation; BMI: body mass index; FEV₁: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity; IPAP: inspiratory positive airway pressure; EPAP: expiratory positive airway pressure; P_a,O₂; arterial oxygen tension; P_a,CO₂: arterial carbon dioxide tension; ns: nonsignificant. ^#: as the device makes it possible to set parameters for the type of mask used in order to abstract the amount of intentional leak, preference was given to the types of masks that could be preset in the device. If this was not possible, the mask used was that with the closest intentional leak. Accordingly, we previously measured the intentional leak for each mask in our laboratory; ^¶: breathing room air or under supplemental oxygen therapy; ⁺: prior to the start of the ventilation in ARF and during the first hour in the morning after the patient was disconnected from the ventilator in CRF and LTMV; ^§: data lacking in 10 patients of this group; ^ƒ: p<0.05 compared to CRF using the Mann–Whitney rank sum test; ^##: p<0.056 compared with ARF. *: p<0.05 compared to ARF.