### Description

Gluck and Corgian used a scoring system to evaluate patients receiving long-term mechanical ventilation at the time of admission to a long-term ventilator unit. This can help identify patients who can be eventually weaned. The authors are from Finch University of Health Sciences and Rush-Presbyterian-St. Luke's Medical Center in Chicago.

Parameters determined on admission to the long-term ventilator unit:

(1) rapid shallow breathing (RSB)

(2) dead space to tidal volume ratio (VD / VT)

(3) static lung compliance

(4) airway resistance in cm H2O per liter per second.

(5) PaCO2 in mm Hg

where:

• Rapid shallow breathing = f / VT = (frequency of breaths per minute) / (tidal volume in liters)

• The dead space to tidal volume ratio can be calculated from the PaCO2 and PCO2 of the expired air (see Respiratory Dead Space Volume, above).

• Static lung compliance was calculated by dividing the tidal volume delivered during the plateau maneuver by the plateau pressure, minus the any positive end-expiratory pressure (PEEP) that the patient was receiving.

• I am not sure of the units for static compliance. If reported in L per cm H2O this should be around 0.262, or 262 mL per cm H2O. The values scored seem to match values for maximal static recoil pressures in cm H2O (see Grippi et al, page 543).

• Airway resistance was calculated by dividing the difference between the peak and plateau pressure by the inspiratory flow, using the square wave inspiratory flow pattern.

Parameter

Finding

Points

rapid shallow breathing

> 180

2

120 – 180

1

< 120

0

VD / VT

> 0.74

2

0.64 - 0.74

1

< 0.64

0

static lung compliance

< 32

2

32 – 36

1

> 36

0

airway resistance

> 17

2

9 – 17

1

< 9

0

PaCO2 in mm Hg

> 64

1

<= 64

0

score =

= SUM(points for all 4 parameters)

Interpretation:

• minimum score: 0

• maximum score: 9

Score

Likelihood of Weaning

4 - 9

unlikely

3

indeterminate

0 - 2

likely