Models for Prediction of Ventilator Weaning and Survival in COPD Patients

 

Parameters based on assigned score:

(1) points for lifestyle prior to current episode

(2) points for cor pulmonale

(3) points for left ventricular failure

 

Parameters based on direct measurement:

(4) FEV1 as percent of predicted, expressed as decimal fraction

(5) serum albumin in g/dL (NOTE: The article gives this as mg/dL, which appears to be a typographic error).

(6) negative inspiratory force (NIF) in cm H2O

(7) tidal volume in mL

 

Parameter	Finding	Points
lifestyle	working	0
	independent in activities of daily living and fully ambulatory	1
	restricted in exercise ability but able to live on own and leave house	2
	housebound but able to perform self-care	3
	bed or chair bound	4
cor pulmonale on ECG	absent	0
	present	1
left ventricular failure (LVF)	absent (no pulmonary edema and LVEF >= 40%)	0
	present (pulmonary edema or LVEF < 40%)	1

 

probability of survival =

= EXP(X) / (1 + EXP(X))

 

X =

= (-3.52) – (0.74 * (points for lifestyle)) + (2.81 * (decimal fraction for FEV1 as percent of predicted)) + (1.54 * (serum albumin in g/dL)) – (1.04 * (points for cor pulmonale)) – (1.53 * (points for LVF))

 

probability of weaning based on premorbid data only =

= EXP(Y) / (1 + EXP(Y))

 

Y =

= (-2.27) – (0.88 * (points for lifestyle)) + (5.6 * (decimal fraction for FEV1 as percent of predicted)) + (1.33 * (serum albumin in g/dL))

 

probability of weaning based on all data =

= EXP(Z) / (1 + EXP(Z))

 

Z =

= (-7.94) – (0.48 * (points for lifestyle)) + (7.73 * (decimal fraction for FEV1 as percent of predicted)) + (1.42 * (serum albumin in g/dL)) + (0.058 * (negative inspiratory force in cm H2O)) + (0.0062 * (tidal volume in mL))