Page 444 - Clinical Application of Mechanical Ventilation

410 Chapter 12

respiratory failure or ARDS when compared to similar patients who are in the
PP improves oxygenation standard supine position (Gattinoni et al., 2001; Meade, 2002; Rialp et al., 2002).
parameters rapidly but it does
not increase the survival rate
of patients with acute respira- Indications and Contraindications. The primary indication for PP is ARDS with in-
tory failure or ARDS. creasing oxygen index (OI) of .30% while supine and during mechanical ventila-
tion. OI requires measurement of the mean airway pressure (mPaw), F O , and
I
2
PaO . See equation below and Appendix 1 for example to calculate the OI.
2
(mPaw * F O )
OI = I 2
PaO 2
Contraindications for PP include increased intracranial pressure, hemodynamic
instability, unstable spinal cord injury, recent abdominal or thoracic surgery, flail
chest, and inability to tolerate PP.
Procedure. If no contraindication for PP exists, the patient is turned to a prone posi-
After 1 hour of PP, an
improvement of the OI by tion for at least 1 hour (stabilization period). After 1 hour, the PaO /F O ratio and
2
I
2
.20% of baseline value sug- the mPaw are measured. An improvement of the OI by ≥20% of baseline value
gests beneficial response.
suggests beneficial response to PP.
For optimal improvement in oxygenation and more stable improvement in the
OI, pediatric patients should remain in the PP for a period longer than 12 hours.
The procedure for PP (preparing the patient, placing the patient in PP and SP) has
been fully described by Relvas et al. in 2003. For adult patients, the duration of PP
should be 6 hours or more depending on patient response and tolerance (Gattinoni
et al., 2001; Meade, 2002).

Complications. Complications of PP include accidental extubation, hemodynamic
instability, pressure wounds or ulcers, residual obstructive and restrictive lung de-
fects, and brachial plexopathy (Curley et al., 2000; Goettler et al., 2002; Neff
brachial plexopathy: Decreased
movement or sensation in the arm et al., 2003; Relvas et al., 2003).
and shoulder.
Tracheal Gas Insufflation

Tracheal gas insufflation (TGI) is a technique that uses a small catheter to pro-
tracheal gas insufflation (TGI):
Use of a small catheter to provide vide a continuous or phasic gas flow directly into the endotracheal tube during
a continuous or phasic gas flow mechanical ventilation. Slusky and Menon described in 1987 the use of a constant-
directly into the trachea during
mechanical ventilation. flow device in conjunction with ventilation. Over the years, innovations have been
made on similar techniques.
Procedure. TGI introduces 5 to 20 L/min of oxygen or air into the endotracheal
TGI introduces 5 to 20 L/
min of oxygen or air into the (ET) tube during mechanical ventilation. This flow is in addition to the flow pro-
endotracheal (ET) tube during vided by the ventilator. The flow provided by the TGI is regulated by a controller
mechanical ventilation.
and is directed through a small catheter to the distal end of the ET tube. The
gas exits the ET tube and arrives just above the carina (Valley Inspired Products,
Burnsville, MN).
The insufflation may be continuous or phasic. In continuous-flow TGI, the gas
flow goes into the airway during inspiration and expiration. Some undesirable effects
of continuous TGI include drying of secretions, mucosal tissue damage, increased
tidal volume delivery, development of auto-PEEP, and increased effort to trigger the
ventilator. In phasic TGI, the gas flow goes into the airway during the last half of

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