Acupunct Med2010;28:115-119 doi:10.1136/aim.2009.001867
Original papers


Immediate effect of acupuncture on the sleep pattern of patients with obstructive sleep apnoea

Anaflávia O Freire1,
Gisele C M Sugai2,
Sônia Maria Togeiro1,
Luiz Eugênio Mello3,
Sérgio Tufik1
Introduction

The pathogenesis of obstructive sleep apnoea (OSA) is complex but it is probably due to a combination of an anatomically small pharyngeal airway1 in conjunction with a sleep-related decline in upper airway dilator muscle activity.2 Control of upper airway muscle activity is complex. Factors that may affect upper airway muscle activity include direct input from the brainstem respiratory central pattern generator,3 chemoreceptive inputs,4 vagal input due to changes in lung volume5 and a tonic wakefulness drive that is present in the respiratory system.6 During wakefulness, patients with OSA have augmented activity of upper airway muscle such as the genioglossus muscle and tensor palatine.7 This increased activity is thought to represent a neuromuscular compensatory mechanism for an anatomically small and more collapsible pharyngeal airway. At sleep onset, this augmented upper airway dilator muscle activity is diminished or lost in association with pharyngeal collapse.8

We have recently demonstrated that acupuncture is more effective than placebo treatment (sham acupuncture)—providing significant changes in the respiratory events assessed by polysomnography, and improving the quality of life of patients with OSA.9 Manual acupuncture (MA) has been practised for thousands of years in China for the treatment of various diseases.10 Only in the past century has its potent alternative, electroacupuncture (EA), been used with increasing frequency in clinical and basic research,11 and several studies suggest that the results of EA and MA differ.12 EA causes the release of β-endorphin and adrenocorticotrophic hormone into plasma, whereas MA releases only β-endorphin.13 In addition to possible differences between EA and MA, a number of studies have suggested that EA at different frequencies causes different types of responses.13 14 Further evaluation showed that low-frequency (2 Hz) EA activated many more somatic afferents than high-frequency stimulation such as 10 and 20 Hz.15 These findings suggest that the central nervous system might have a frequency-specific response to peripheral electric stimulation.16
Between January 2007 and August 2008, we screened individuals for inclusion in this research. Eligible patients had a significant symptomatic OSA confirmed by a full polysomnographic (PSG) study with an AHI >15/h and <30/h (moderate OSA), were aged 30–70 years and were all acupuncture naïve. Patients with a high alcohol intake (>80 g/day), morbid obesity, significant lung disease, neurological disease, intellectual deficit, problems in the skeletal facial framework, central apnoea, insomnia, who had already undergone oropharyngeal operations, who had been treated with continuous positive airway pressure or oral devices and were taking any hypnotic drugs were excluded.


Material and methods


Trial design and participants

Between January 2007 and August 2008, we screened individuals for inclusion in this research. Eligible patients had a significant symptomatic OSA confirmed by a full polysomnographic (PSG) study with an AHI >15/h and <30/h (moderate OSA), were aged 30–70 years and were all acupuncture naïve. Patients with a high alcohol intake (>80 g/day), morbid obesity, significant lung disease, neurological disease, intellectual deficit, problems in the skeletal facial framework, central apnoea, insomnia, who had already undergone oropharyngeal operations, who had been treated with continuous positive airway pressure or oral devices and were taking any hypnotic drugs were excluded
A total of 40 patients were eligible for the study and were submitted to a new PSG at the start of the study. They were randomly allocated by a blinded independent researcher to the following four groups: MA group, EA 10 Hz group, EA 2 Hz group and control group (n=10 each group). After randomisation, study procedures remained blind except for the researcher who applied MA/EA. All patients signed an informed consent form after receiving details of the possible risks ,The ethical committee of the Universidade Federal de São Paulo approved the study protocol (number 0503/06). The study was conducted according to a strict protocol.
Needle type: MA and EA

We used single-use, sterile, cooper-handle, prepacked needles with guide tubes, 40×0.25 mm (Dongbang Acupunture; Boryeong City, South Korea). Before insertion of the needles all the points were sterilised with ethanol. The location and depth of insertions were as described in traditional texts.17 The points used were as follows: LU6, LU7, LI4, LI20, GV20, CV23, ST36, ST40, SP6, KI6. An extra point is located between the hyoid bone and the menton symphysis (Shanglianquan).

For EA the electrodes were placed in the points of the neck (deep enough to reach the genioglossus muscle —CV23 and Shanglianquan) (figure 1) and also along the body in LI4 and ST36. The electrodes were connected to LI4 and ST36 at both sides. The EA stimulation, consisting of 0.45 ms2 wave pulses at 2 or 10 Hz, was delivered by a constant current EA machine (Plexus AP 585 electrostimulator; Accurate Pulse/Biotherapy, Lautz, Brazil) to produce a moderate muscle twitch. The intensity of stimulation was typically 0.6–0.8 mA.
The choice of acupoints was based on their specific characteristics, as already described.9 In the MA group the needles were inserted and manually stimulated until the deqi sensation of heaviness and numbness was elicited.18 All acupuncture procedures were done by an experienced doctor, specialist in acupuncture, according to traditional Chinese medicine acupuncture methods.18 Body needles were left in situ for 30 min in the ventral part of the body. Immediately after the acupuncture or electroacupuncture stimulation the subjects were prepared for the PSG recordings.
Sleep recordings were scored according to the criteria of Rechtshaffen and Kales19 and respiratory events were considered according to the criteria published by the American Academy of Sleep Medicine in 1999.20 Two blinded experienced doctors assessed all the results.
Statistical analysis

Baseline characteristics of the patients were recorded as the median and compared between groups by the Kruskal–Wallis test. The results among groups were compared before and after the procedures by the Kruskal–Wallis test. The differences between the groups before and after the procedures were compared using a Mann–Whitney test.21 The level of statistical significance was set at 0.05. All data were computer-analysed using Statview software.Comparison of the results between the groups after treatment showed that the MA group and the EA 10 Hz group significantly differed from both the EA 2 Hz and control groups in all the respiratory parameters, specifically in the primary outcome the AHI (figure 2). Those differences were supported by significant changes in other outcomes. The EA 10 Hz group differed from the control group and EA 2 Hz in the respiratory events (p=0.006; p=0.025, respectively). The MA was significant different only from the control group

Discussion

The results of our study demonstrate that median frequency EA 10 Hz and MA exerts better immediate effects than low frequency EA 2 Hz in reducing the AHI as well as the number of nocturnal respiratory events of patients presenting with moderate OSA. In a previous study our group showed that MA was effective in providing significant changes in polysomnographic evaluations as well as in the quality of life of patients with OSA after 10 weekly sessions of acupuncture.9 The speculative hypothesis for this improvement was the involvement of serotonergic pathways22 23 in the responses mediated by acupuncture as well as its anti-inflammatory effect.24
p=0.015). Nevertheless, in the Hypopnoea Index the MA differed from the control group and EA 2 Hz (p=0.010; p=0.034, respectively) and the EA 10 Hz group only differed from the control group (p=0.019). No adverse events occurred during the trial.