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Mechanical Ventilation in Nontraditional Settings 607

gas volume to increase. For users of a non-pressure-compensated ventilator while
traveling by air, the set tidal volume should be decreased during ascent to prevent
hyperinflation.
Conversely, during landing of an airplane, an increasing barometric pressure
causes the gas density to increase. A higher gas density compresses the gas vol-
ume. This means the delivered volume decreases during landing. To compensate
for loss of volume, the set tidal volume should be increased during descent.
One study estimates that the tidal volume can be reduced by 3% per 1,000 ft of
One study estimates ascent or increased by 3% per 1,000 ft of descent (Schedler et al., 2007). Another
that the tidal volume can be method for volume compensation is to monitor the ventilator outputs (tidal vol-
reduced by 3% per 1,000 ft of
ascent (or increased by 3% per ume, frequency, and minute ventilation) and make adjustments to the tidal volume
1,000 ft of descent). and frequency during ascent and descent.

Portable Oxygen Concentrator

Most commercial airplanes use 8,000 ft of cabin pressure altitude at any cruis-
ing altitude or speed. At this cabin pressure, it is equivalent to a barometric
pressure of 564 mm Hg or a P O of 59 mm Hg. Since arterial oxygen satura-
2
A
tion is in part determined by the gas tension, a reduced P O can lead to hy-
2
A
poxia and associated physiologic changes (e.g., hyperventilation, tachycardia,
tachypnea).
Altitude hypoxia affects all individuals, but it exerts a more profound in-
fluence on those with preexisting heart or lung diseases. Hypoxia induced by
high altitudes can be treated with supplemental oxygen. For intermittent users
of ventilators, oxygen therapy is recommended while breathing spontaneously.
Prophylactic oxygen therapy reduces the work of breathing and alleviates the
development of ventilatory failure due to prolonged exacerbation (Luks et al.,
2007).
The Air Carrier Access Act does not require airlines to provide oxygen during
The Air Carrier Access Act flights. Some airlines charge a fee for providing supplemental oxygen per flight
does not require airlines to
provide oxygen during flights. segment. Airlines may allow passengers to bring a portable oxygen concentrator
(POC) on board. Again, as with a portable ventilator, planning must be made
ahead of time to ensure smooth and safe travel. In 2005, the FAA approved sev-
eral POCs for air travel. Examples of the approved POCs that weigh less than
10 lbs, along with their maximum battery duration, include: AirSep FreeStyle
(4.4 lbs, 10 hrs), Delphi Central Air (9.8 lbs, 3 hrs 25 min), Inogen One G2
(7 lbs, 8 hrs), Invacare XPO2 (6 lbs, 7 hrs), Inova Labs LifeChoice (4.9 lbs,
5 hrs), and Phillips Respironics EverGo (8.5 lbs, 12 hrs).
Since airlines are not required to provide direct-current electricity for the
POC, a passenger must bring along sufficient batteries to power the POC. The
The rule of thumb is to rule of thumb is to have enough battery life to power the POC for at least 150%
have enough battery life to
power the POC for at least of the one-way travel time. The POC and batteries must be able to fit under the
150% of the one-way travel seat or on the lap. Refer to the Federal Aviation Administration website (www
time.
.faa.gov) for current rules and regulations on air travel with a POC or portable
ventilator.

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