OBSTRUCTIVE SLEEP APNEA PAPERS; GENERAL
Katz I, Stradling J, Slutsky AS, Zamel N and Hoffstein V; Do patients
with obstructive sleep apnea have thick necks? Am Rev Respir Dis 1990;141:1228-1231.
Study of 123 obese patients with obstructive sleep apneas showed that external
neck circumference correlated with respiratory disturbance index. Patient’s
weight appeared to correlate best with neck size, which was roughly linear above
neck circumferences of 16 inches and greater.
Gall R, Isaac L and Kryger M; Quality of life in mild obstructive sleep
apnea. Sleep 1993;16:S59-61.
42 adult males with RDIs <20 had impaired POMS (Profile of mood states),
Katz adjustment scale and another psychosocial symptom check list.
My comment; paper is reinforcing the fact that that even mild sleep apnea can
have deleterious effects.
Chervin RD, sleepiness, fatigue, tiredness and lack of energy in obstructive
sleep apnea. CHEST, 2000; 118:372-379.
Significant article showing that sleepiness is not the most frequent subjective
complaint associated with significant Obstructive Sleep Apnea. Observational
study of 190 men and women with a mean age of 49 years, AHI of 32 and a MSLT
of 7 minutes. Subjects more frequently reported problems with fatigue, tiredness,
and lack of energy than sleepiness (57%, 61%, 62% vs. 47%) Almost 40% felt that
lack of energy was their most significant symptom vs. 22% for sleepiness. In
all domains, women complained more frequently than men of the aforementioned
symptoms. Other interesting points from the article;
1. Patients with higher AHIs were no more likely to report frequent sleepiness
or lack of energy…
2. MSLT sleepiness was not correlated with level of symptom complaint scores.
3. Compared to women, men often have more severe sleep apnea, indistinguishable
MSLs or MSLTs, and less subjective sleepiness as measured by the Epworth sleepiness
scale (ESS)
4. Up to 80% of Obstructive Sleep Apnea is undiagnosed in the USA; the lack
of a complaint of sleepiness should not dissuade the practitioner from doing
a sleep evaluation if other clinical evidence is present.
Le Bon O, Hoffmann G, Tecco J, Staner L, Noseda A, et al. Mild to moderate
sleep respiratory events-one negative night may no be enough. CHEST
2000;118:353-359.
Showed that a significant number of patients with Obstructive Sleep Apnea had
a negative initial PSG. 243 men and women who were mildly to moderately over
weight (BMI 28.7±5.8) were studied. 113 (67%) had AHIs <20 had a repeat
study. 54% of the patients increased their RDI on the second night, while 28%
had a decreased RDI on the second night study. Mean RDI increased from 12.3
to 15.5 with the largest changes occurring in the number and indices of apneas
19.9 to 28.3. No factor analyzed correlated with an increased RDI the second
night except the AHI on the first night.
Other conclusions from this study:
1. Showed that a first night effect occurred in patients with Obstructive Sleep
Apnea. There was a considerable night-to-night variability in AHIs and microarousal
indices
2. Non-respiratory microarousals were more frequent on the first night whereas
respiratory associated micro arousal indices were more frequent on the second
night study.
3. A clear first night effect was seen in the N1 study when compared to the
N2 PSG: (in minutes)
a. Increased total sleep time (308.6 vs. 407.3)
b. Reduced sleep efficiency (71.9 vs. 77.9)
c. Prolonged sleep latency (41 vs. 31)
d. Increased stage shifts (37.7 vs. 33.5)
e. Increased WASO (73.2 vs. 64.8)
f. Increased numbers of wakenings hour (7.9 vs. 6.2)
g. SWS (37.9 vs. 42.2)
h. REM (42.5 vs. 49.9)
i. REM latency, min (95.5 vs. 88)
Black J, Guilleminault C, Colrain JM and Carrillo O. Upper airway resistance
syndrome; central electroencephalograph power and changes in breathing effort.
Am J Respir Crit Care Med 2000;162:406-411.
The upper airways resistance syndrome (UARS) is defined by the following criteria
1. Excessive daytime sleepiness (EDS) and tiredness
2. Progressive increases in respiratory effort as measured by esophageal pressure
(Pes) terminated by an arousal (AR)
3. UARS events most common in Stage II sleep
Recently this group has noticed increased respiratory effort not associated
with an AR. Present study expanded the definition of an arousal to include changes
in the EEG not measured by standard PSG by using Fast Fourier Transformations
for approximately one half minute before and after the nadir of Pes. Low frequency
bands (delta) were increased more frequently around the time of these events.
Delta power was increased (alpha and theta were also increased) in both arousal
and non-arousal events. Most often between 2 and 6 seconds before and after
events. Showed an example of an event demonstrating a run of delta waves during
an event. (this group comments that they have reported “hypersyncronus”
delta activity associated with respiratory events with and without AR activity
previously.
5/15 (33%) of patients studied did not snore.
Fietze I, Quispe-Bravo S, Schiller W, Rottig J, Penzel T et al, Respiratory
arousals in mild Obstructive Sleep Apnea syndrome. Sleep 1999;22:583-
Studied respiratory events that did not meet strict apnea and hypopnea criteria
that were associated with arousals. (AR) Researchers divided ARs into R type
associated with respiratory events or M type associated with body movements.
Patients were younger, X¯ 42 years with low RDIs, X¯ of 10. BMI moderately
increased at 28. All patients complained of sleepiness and snoring. Pts had
diagnostic and three Continuous Positive Airway Pressure adjustment nights.
Respiratory events were scored by any visible reduction in effort or flow, which
were associated with an AR. The R index X¯ was 5.2 and the M index X¯
was 9.7. Continuous Positive Airway Pressure lowered the RDI and the R index
to P<0.001 and P<0.01 respectively. R index means reduced from 5.2 to
1.2. The M index did not change significantly. MSL increased, as did subjective
well-being.
Sanders MH, Kern NB, Costantino P, Stiller RA, Studnicki K, Coates J,
Orris S Schimerman S.Adequacy of prescribing positive airway pressure therapy
by mask for sleep apnea on the basis of a partial-night trial Am Rev Respir
Dis; 1993;147:116
“…data indicate…OSA and satisfactory prescription for (CPAP) can be established during a single psg study in a majority of patients, a substantial proportion of them will require alteration of that prescription on a subsequent night because of inadequate pressure, changing tolerance of the patient-device interface, or change of the positive pressure modality. “
Methods
50 consecutive patients; CPAP initiated at 5cm H20 pressure with upward titration
in increments of 2.5 com of H20 (PSG PPp)…patient-device interface was
changed during the study as mandated by patient intolerance, including claustrophobia,
inability to breath exclusively through the nose, nasal congestion and/or discomfort…”
Subsequent to the split night study a full CPAP titration was done (PSG PPF)
Results
48/50 nocturnal studies 2 were day sleepers.
Total sleep time during the diagnostic part of the study (PSGD) was 90 ±
24 minutes.
While there was a considerable difference in sleep stages between the PSGD and
the PSG PPp and PSG PPF the sleep stages were similar in the partial and full
CPAP trials. (That is, the sleep stages were similar for both CPAP adjustment
attempts. 7/50 patients had no REM sleep on the final prescription for CPAP
on the PSGD night, but 5 of those had it on the PSG PPF titration.
31/50 or 62% had no change in CPAP Rx after the PSG PPF; 11/50 required a 2.5
cm increase and 3/50 a 5 cm H20 increase. The change in CPAP pressure was not
related at all to any change in interface. 15/50 or 30% required an interface
change. Seven patients were changed to BiPap on the PSG PPF night.
Comment; Appears that the so-called split night study diagnosing and CPAP adjustment can be an effective way to save money by reducing the number of sleep studies required to diagnose and treat OSA. Thirty eight percent of the patients, however, did need an alteration in the CPAP pressure prescription
Fletcher E; Role of nocturnal oxygen therapy in obstructive sleep apnea, when
should it be used? Chest 1990;98:1497-1504.
This dated summary article reviews the older literature well. A few summary
points from the conclusion are useful.
1. Use of 02 in Obstructive Sleep Apnea increases the 02 nadir, but may increase
respiratory acidosis. No deleterious effects of this acidotic increase have
been shown.
2. Many of the studies on use of 02 in Obstructive Sleep Apnea used large and
not clinically relevant doses of 02.
3. There is an increase in apnea duration, but the overall time in apnea may
be less. Apnea frequency was also reduced. The fall in desaturation was reduced
by 50%.
4. 02 therapy in some studies greatly reduced the number of central and mixed
apneas, but increased the relative number of obstructive apneas.