Sleep-disordered Breathing and Hypotension, 2001, Guilleminault et al.

[nataliezzz]

Sleep-disordered Breathing and Hypotension
Christian Guilleminault, John L. Faul, Riccardo Stoohs
https://www.atsjournals.org/doi/10.1164/ajrccm.164.7.2011036 (PDF available)

Abstract

We investigated the presence of low blood pressure (BP) in 4,409 subjects referred for overnight polysomnography. A low resting arterial BP (systolic BP < 105 mm Hg, diastolic BP < 65 mm Hg) was present in 101 subjects (2.3%). Low BP was more prevalent in subjects with upper airway resistance syndrome (UARS) (23%) than in subjects with obstructive sleep apnea syndrome (OSAS) (0.06%), parasomnia (0.7%), restless leg syndrome (0.9%), or psychological insomnia (0.9%). In order to investigate BP homeostasis, we conducted polysomnography followed by tilt-table testing on 15 subjects with orthostatic intolerance (OI) and UARS, five normotensive subjects with UARS, five subjects with insomnia and low BP, 15 subjects with OSAS, and 15 healthy control subjects. Fifteen subjects with UARS and OI and 15 healthy controls also underwent 24-h ambulatory BP monitoring. Subjects with OI and UARS had lower mean daytime systolic (119 ± 28 mm Hg) and diastolic (75 ± 18 mm Hg) BP than did control subjects (131 ± 35 mm Hg and 86 ± 19 mm Hg, respectively) (p < 0.05). During tilt-table testing, subjects with UARS and a history of OI had a greater decrease in systolic BP (27 ± 3 mm Hg) than did control subjects (7.5 ± 1.6 mm Hg), subjects with OSAS (6.8 ± 1.2 mm Hg), normotensive subjects with UARS (7.2 ± 0.84 mm Hg), or hypotensive insomniacs (7.4 ± 1.1 mm Hg) (p < 0.01). We conclude that approximately one fifth of subjects with UARS have low BP and complain of OI. Tilt-table testing may be indicated to confirm orthostatic intolerance in subjects with UARS.

 

[nataliezzz]

Low BP in this study was considered <105/65; usually it is considered <90/60. Still, the fact that all 15 UARS patients meeting their criteria for low BP who underwent tilt table testing had orthostatic hypotension seems striking.

Some relevant excerpts from the paper:

All subjects with UARS and low BP complained of OI and cold peripheries.

During tilt-table testing, subjects with low BP and UARS who had a history of orthostatic intolerance had a faster resting HR (90 ± 5 beats/min [bpm]) than did either control subjects (72 ± 4 bpm) or subjects with OSAS (74 ± 5 bpm) (p < 0.01).

The coexistence of resting tachycardia and orthostatic hypotension (demonstrable in this study during tilt-table testing) is suggestive of clinically significant hypovolemia. This study was not designed to measure blood or plasma volume; however, OI and OH were not present in other groups of subjects with sleep-disordered breathing (normotensive subjects with OSAS, hypotensive subjects with insomnia, and UARS patients with normal BP). This difference could not be attributed to differences in age or BMI between the five diagnostic groups

All of the UARS patients had normal 30:15 R-R interval ratios during tilt table testing, "which argues against a diagnosis of autonomic neuropathy" (see explanation below):

In normal subjects there is a characteristic biphasic HR response to head-up tilt. There is an immediate shortening of the R–R interval that is most pronounced around the 15th beat after standing, followed by a lengthening of the interval (relative bradycardia) that is greatest around the 30th beat after standing. The R–R intervals at beats 15 and 30 are measured on the ECG. The ratio of 30:15 has been demonstrated as characteristic of a normal response; subjects with an abnormal absence of rebound bradycardia will have a ratio of 1 or less, whereas the normal ratio will be 1.04 or more.

A 30:15 R–R ratio of > 1.0 is considered normal, but a 30:15 ratio of < 1.0 is suggestive of autonomic neuropathy. The values for 30:15 R–R ratios (24) were 1.22 ± 0.05, 1.23 ± 0.04, 1.28 ± 0.05, 1.15 ± 0.03, and 1.2 ± 0.04 in the UARS, control, OSAS, normotensive UARS, and hypotensive UARS groups, respectively

This was the criteria for UARS:

complaints of tiredness, fatigue, or sleepiness; presence of abnormal scores on sleepiness and/or fatigue scales (18, 19); apnea-hypopnea index (AHI) < 5 events/h; presence of respiratory event- related arousal (RERAs) at > 5 events/h (22); lowest oxygen saturation > 89%; recording of Pes crescendos terminated with arousal; and a Pes reversal (with a frequency of at least 5 events/h and the possibility that RERAs and Pes crescendos overlap)

All of the UARS patients in the study had an abnormally small oral cavity based on objective measurements:

Subjects with UARS were also examined by an otolaryngologist. A craniofacial evaluation performed by a specialist indicated the presence of at least one of the following: crossbite, long face, high-arched hard palate with narrow maxilla, and small mandible with either decreased anteroposterior length or decreased intermolar distance (20, 23). The anatomic findings always resulted in a small oral cavity impacting on the resting position of a normal-size tongue.

The index calculated on the basis of oral cavity measurements was abnormal in all subjects (20). Only three subjects had wisdom teeth (23). Cephalometric radiographs demonstrated an abnormally small airway space behind the base of the tongue (in 87 of 89 subjects).