Chest
Volume 93, Issue 6, June 1988, Pages 1199-1205
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Obstructive Sleep Apnea and Cephalometric Roentgenograms: The Role of Anatomic Upper Airway Abnormalities in the Definition of Abnormal Breathing During Sleep

https://doi.org/10.1378/chest.93.6.1199Get rights and content

In a six-month period, 157 obstructive sleep apnea syndrome (OSAS) patients seen consecutively in clinic had standardized cephalometric roentgenograms and underwent polygraphic monitoring during sleep. Different variables, including cephalometric landmarks, body mass index (BMI), and polygraphic results (particularly degree of O2 saturation and number of abnormal breathing events), were statistically analyzed. As a rule, OSAS patients had upper airway anatomic abnormalities and an elevated BMI: massive obesity was associated with less anatomic abnormality, less nocturnal sleep disruption, and longer total sleep time (TST). Patients having a high respiratory disturbance index (RDI) were more likely to have upper airway anatomic abnormalities; they slept for a shorter time and had increased stage 1 non-rapid eye movement (NREM) sleep but decreased stage 3 and 4 and REM sleep. Long mandibular plane to hyoid bone (MP-H) distance and width of the posterior airway space (PAS) (space behind the base of the tongue) were statistically significant predictors of elevated RDI. The cephalometric variables were much less useful for predicting frequency of O2 saturation drops below $0 percent. The patient population can be subdivided into (a) patients with clear anatomic abnormalities and low BMI, (b) patients with morbid obesity with few abnormal cephalometric measurements, and (c) patients who have variably increased BMI and abnormal cephalometric measurements. This is the largest group. We concluded that standardized cephalometric roentgenograms can be useful in determining the appropriate treatment for OSAS patients.

Section snippets

Patient Population

None of the 157 patients meeting the above or preselected criteria was eliminated from the study. It consisted of 143 men, with a mean age of 49.4 ±11.3 (SD) years (median 50, range 21 to 74), and 14 women, mean age, 51.0 ±10.4 years (median 51.5, range 32 to 68) (Table 1). Ail had cephalometric roentgenograms and one night of polygraphic monitoring as part of the experimental protocol. The BMI (weight × 10,000/height2) was calculated by the method of Khosla and Lowe.10

Polysomnographic Recordings and Definition of Breathing Abnormalities

The variables monitored

DISCUSSION

The different analyses demonstrate, once again, that obesity—indicated by BMI—is an important factor in the definition of RDI and O2-80-I. This population is overweight. Based on epidemiologic data, one expects 26.7 percent of the US male population aged 40 to 65 years to have a BMI >27.8.13 We found that more than 50 percent of our population had a BMI >29 kg/m2 (median, 29.7). But obesity is not the only risk factor for OSAS; cephalometric measurements are also significant, for the definition

ACKNOWLEDGMENT

We would like to thank Boyd Hayes and David Cobasko for providing technical assistance and Alison Grant for editing the manuscript.

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Supported by General Clinical Research grant 00070 funded by the National Institutes of Health.

Manuscript received August 10; revision accepted December 17.

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