Respiratory Diseases and the Fire Service

Commonly Used Laboratory Investigations
Complete blood count (polycythemia)
Arterial blood gas (obesity hypoventilation syndrome)
Electrocardiogram
Echocardiogram (right heart failure)
Pulmonary function testing (lung volume and saw tooth pattern on flow volume loop)
Cephalometrogram
Table 2-11.4: Commonly Used Laboratory Investigations
Treatment of OSA
The goals of treatment of OSAS are to alleviate excessive daytime sleepiness
(EDS) and to reduce the frequency of apnea-hypopnea (AHI) to levels not
associated with increased cardiovascular and cerebrovascular risk. Attenuation
of disruptively intense snoring may have important social implications, however,
if the snoring is primary and not associated with OSA, then treatment of such
snoring should be decided on its own merits.
Mild OSA (AHI = 6 – 15 events/hour) has not been clearly associated with
increased cardiovascular and cerebrovascular risk. Thus, those with mild OSA
who lack sleepiness may be best treated with education regarding the causes
and risks of OSA, counseling with regard to good sleep hygiene, diet and weight
loss, avoidance of alcohol, sedatives, and antihistamines, and possibly use of
positional therapy (techniques to avoid sleeping supine). 19 Even for people who
lack OSA, regular sleep-wake hours, sufficient sleep hours (most adults require
7 – 8 hours of sleep per day), exposure to sunlight in the early morning, daily
exercise (30 – 60 minutes/day but not within two hours of bedtime), limiting
caffeine consumption, and completing the evening meal three or four hours
before bedtime should be encouraged strongly. Weight loss has been shown
to reduce mean AHI. 20,21
People with mild OSA and coexisting EDS and people with moderate or severe
OSA (AHI = 16 – 29 events/hour, and 30 or more events/hour, respectively) with
or without EDS need additional treatment specifically directed to attenuating
the frequency of apnea and hypopnea. In successfully doing so, sleep becomes
less fragmented so that daytime alertness is restored. Furthermore, the
apnea-hypopnea-hypoxia associated release of catecholamines and proinflammatory
mediators is sufficiently attenuated to remove cardiovascular
and cerebrovascular risks from OSAS. CPCP, invented by Sullivan in 1981, 22
is the most commonl-prescribed and overall most effective treatment of
OSAS and has replaced tracheostomy (now rarely performed for OSAS) as the
treatment of choice. Regular CPAP use has been shown to improve quality of
life, reduce daytime sleepiness, improve neuropsychiatric function, 23,24 reduce
the need for medication to treat hypertension, and reduce the risk for adverse
cardiovascular and cerebrovascular events among people with OSAS. 25 With
CPAP treatment, positive airway pressure (PAP) is applied to the nose, or nose
and mouth, through nasal “pillows”, nasal mask, or full facemask that covers
the nose and the mouth. The PAP is transmitted across the nasal and oral
cavities to the pharynx. Optimal PAP is determined during an overnight sleep
study and it is that PAP that keeps the pharynx open (like an air splint) while
the person sleeps in all positions and all sleep stages so that the AHI while
using CPAP is < 6 events per hour (Figure 2-11.3).
Chapter 2-11 • Sleep Apnea Syndrome 183