Limited predictability of maximal muscular pressure using the difference between peak airway pressure and positive end-expiratory pressure during proportional assist ventilation (PAV)

Table 1 Patient demographics and respiratory mechanics

Case	Age (years)/Sex	Diagnosis	Days on MV/ETT size (mm)/ΔP_ETT (cmH₂O)	Baseline FiO₂/PEEP (cmH₂O)	E_rs (cmH₂O/L)	E_cw (cmH₂O/L)	R_max (cmH₂O/L/S)	R_min (cmH₂O/L/S)	ΔP_oes/ΔP_aw
1	61/M	Emphysema, dementia	13/7.5/3.73	0.35/0	21.71	9.96	22.38	10.37	0.94
2	88/M	Pneumonia, COPD	7/7.0/4.92	0.40/8	15.28	5.57	27.11	21.55	1.03
3	80/F	UTI	9/7.5/3.61	0.25/8	18.24	3.93	10.05	7.99	1.00
4	67/F	MRSA bacteraemia	8/7.5/4.05	0.30/6	32.62	9.52	11.08	7.21	1.11
5	80/F	UTI, old stroke	4/7.5/5.36	0.40/6	21.18	6.06	22.29	17.93	0.91
6^b	88/F	UTI, CHF	4/7.5/5.99	0.40/6	30.51	12.54	21.26	16.73	0.92
7	54/F	Pneumonia, old stroke	18/7.0^a/1.97^a	0.30/6	23.04	5.13	17.25	13.69	1.03
8	67/M	Pneumonia	4/7.5/3.93	0.40/6	16.74	3.00	12.46	9.31	0.92
9	79/F	Pneumonia, CHF	8/7.5/6.07	0.30/6	23.98	6.28	22.02	16.95	0.81
10	74/M	COPD	3/7.5/3.71	0.30/6	7.73	4.24	23.52	13.35	1.11
11^c	84/F	UTI, parkinsonism, asthma	4/7.5/3.86	0.35/6	21.61	6.72	20.88	13.34	0.77

^aTracheostomy tube and ΔP_ETT only an approximation as equation only available for an 8.0-mm tracheostomy. ^bCheyne-Stokes breathing noted. ^cEvident abdominal muscle contraction noted. FiO ₂ inspired oxygen fraction, ETT endotracheal tube, CHF congestive heart failure, COPD chronic obstructive pulmonary disease, E _rs passive respiratory system elastance, E _cw passive chest wall elastance, F female; M male, MV mechanical ventilation, MRSA methicillin-resistant Staphylococcus aureus, PEEP positive end-expiratory pressure, Rmax passive maximum end-inspiratory resistance, Rmin passive minimum (airway) end-inspiratory resistance, UTI urinary tract infection, ΔP _oes /ΔP _aw ratio of oesophageal pressure drop to airway pressure drop during airway occlusion, ΔP _ETT pressure loss through endotracheal or tracheostomy tube

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