- by Dr Raghavendra K S Senses ENT care Center
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- Jun 14 2017
Correlation Between Retropalatal Collapse as Observed During Muller’s Maneuver to Severity of OSA
Objective of the study was to evaluate the reliability of Muller’s maneuver (MM) with the severity of obstructive sleep apnea (OSA) at the retropalatal level. Case series of 58 adult patients diagnosed to have OSA. Sleep apnoea clinic in a tertiary referral center in south India. Fifty-eight adult OSA patients underwent outpatient based MM under local anaesthesia. Collapse of hypopharynx and the retroglossal regions were assessed during a maximal inspiratory effort against the closed mouth and sealed nose (reverse valsalva). Correlation co efficient was used to compare MM grade with apnea–hypopnea index (AHI) scores. Severity of OSA based on AHI scores were compared with the results of Muller’s maneuver at the retropalatal level. The correlation coefficient was 0.213, hence no correlation was found, p value was 0.019, which was not statistically significant. MM is an useful tool for evaluation of upper airway collapse. The advantages include simplicity, cost-effectiveness, relatively easy to perform, thorough evaluation of upper airway. The pitfalls of the procedure includes the subjectiveness of the procedure and the fact that it is performed on awake patients and therefore remains an indirect estimation of obstruction that occurs during sleep. In our study, we did not find correlation between the severity of OSA based on the AHI scores and the collapse at the retropalate level assessed by the Muller’s maneuver.
Obstructive sleep apnea (OSA) is a challenging and an increasingly recognized condition which we come across in our daily practice. OSA primarily results from collapse of the upper airway during sleep. The understanding of the pathophysiology of OSA has evolved over the last several decades but it is not fully understood. The cause and mechanisms of this collapse are now thought to be multifactorial and multilevel, hence the evaluation of the upper airway plays a central role in assessing the patient.
These methods include manometry, radiographic studies including computed tomography, dynamic MRI, fluoroscopy and cephalometry and office procedure such as the Muller’s maneuver
MM has been used widely by clinicians during the pre operative evaluation of patients diagnosed with OSA. A review of literature shows positive correlation between MM and retro palatal collapse
Trudo et al. have demonstrated that retropalatal airway volume is significantly reduced during sleep, retroglossal volume remains unchanged in comparisons of sleep and wakefulness.
The present study aims to confirm the reliability of MM with the severity of OSA at the retropalatal level.
All patients underwent overnight polysomnography (PSG) in our hospital sleep laboratory. Data were recorded for stages of sleep, oxygen saturation and number of events of hypopnoea and apnea per hour. Apnea was defined as cessation of breathing for more than 10 s and hypopnoea was defined as 50 % reduction in airflow for more than 10 s associated with more than 4 % decrement in the oxygen saturation. The AHI was defined as sum of number of events of apnea and hypopnoea per hour. Oxygen saturation of more than 90 % was considered normal.
Fifty-eight consecutive patients were examined from August 2008 to December 2010. The mean age was 42.3 years. The gender distribution of the cases in our study was 53 (91 %) males and 5 (9 %) females. Severity of OSA included 3 (5.1 %) patients who had mild OSA, 9 (15.51 %) patients who had moderate and 46 (79.39 %) patients who had severe OSA. The mean AHI scores were 74.7.
The MM at the retropalate level showed, 12 patients (20.68 %) had grade 1 collapse, 23 patients (39.65 %) had grade 2 collapse, 22 patients (37.93 %) had grade 3 collapse and 1 patients (1.72 %) had grade 4 collapse.
Severity of OSA based on AHI scores were compared with the results of MM at the retropalatal level. The correlation co-efficient was 0.213, hence no correlation was found, p value was 0.019, which was not statistically significant.
Grade of Muller’s Maneuver at Retropalate Level
The MM is a subjective test that consists of making the subject to perform a forced inspiratory effort against an obstructed airway with the endoscopic visualization of the upper airway. The upper airway collapse is mainly assessed at three different levels. They are the hypopharynx, base of tongue and retropalate. The degrees of collapse are graded from 0–4.
MM is a useful tool used by the clinicians in the evaluation of upper airway collapse. The advantages include simplicity, cost-effectiveness, relatively easy to perform, thorough evaluation of upper airway and widespread availability
There are certain potential criticisms of the procedure which includes the subjectiveness of the procedure and the fact that it is performed on awake patients and therefore remains an indirect estimation of obstruction that occurs during sleep
n our study, we did not find correlation between the severity of OSA based on the AHI scores and the collapse at the retropalate level assessed by the Muller’s maneuver.
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