Swallowing activity assessed by ambulatory impedance-pH monitoring predicts awake and asleep periods at night

Links Between Swallowing and Consciousness: A Narrative Review

This literature review explores a wide range of themes addressing the links between swallowing and consciousness. Signs of consciousness are historically based on the principle of differentiating reflexive from volitional behaviors. We show that the sequencing of the components of swallowing falls on a continuum of voluntary to reflex behaviors and we describe several types of volitional and non-volitional swallowing tasks. The frequency, speed of initiation of the swallowing reflex, efficacy of the pharyngeal phase of swallowing and coordination between respiration and swallowing are influenced by the level of consciousness during non-pathological modifications of consciousness such as sleep and general anesthesia. In patients with severe brain injury, the level of consciousness is associated with several components related to swallowing, such as the possibility of extubation, risk of pneumonia, type of feeding or components directly related to swallowing such as oral or pharyngeal abnormalities. Based on our theoretical and empirical analysis, the efficacy of the oral phase and the ability to receive exclusive oral feeding seem to be the most robust signs of consciousness related to swallowing in patients with disorders of consciousness. Components of the pharyngeal phase (in terms of abilities of saliva management) and evoked cough may be influenced by consciousness, but further studies are necessary to determine if they constitute signs of consciousness as such or only cortically mediated behaviors. This review also highlights the critical lack of tools and techniques to assess and treat dysphagia in patients with disorders of consciousness.

Post-reflux swallow-induced peristaltic wave (PSPW): physiology, triggering factors and role in reflux clearance in healthy subjects

BACKGROUND AND AIMS

The underlying physiology of post-reflux swallow-induced peristaltic wave (PSPW) is unclear. We aimed to: 1) calculate the probability of a random association between reflux and PSPW; 2) characterize factors that could underlie triggering of PSPW and 3) assess the chemical clearance effect of PSPW in healthy asymptomatic subjects.

METHODS

A total of 251 impedance-pH tracings from healthy asymptomatic subjects were analysed. Twenty consecutive tracings from this pool with 20-40 reflux episodes/24 h and a PSPW index higher than 50% were separately analyzed to evaluate the probability of a random association between reflux and PSPW. The characteristics of reflux episodes followed by a PSPW were compared with those not associated with PSPW.

RESULTS

A mean time interval of 29.3 s between a reflux episode and the first swallow captured 71% of total reflux episodes, and 67% of accompanying swallows were non-random. Compared to reflux without PSPW, reflux episodes with PSPW were more frequently acidic (P = 0.048), mixed with gas (P < 0.0001), of high proximal extent (P < 0.0001), while awake (P < 0.0001), and with shorter chemical clearance time (P = 0.040). High proximal extent, gas presence and occurring while awake were independent factors associated with PSPW (P < 0.0001).

CONCLUSION

Using a time window between reflux and PSPW of around 30 s, the probability of a chance association is around 30%. Reflux episodes with high proximal extent, containing gas and occurring while awake are important factors associated with PSPW in healthy subjects. Reflux episodes with PSPW have a shorter chemical clearance time.

A Novel Sleep Positioning Device Reduces Gastroesophageal Reflux: A Randomized Controlled Trial

GOAL

We hypothesized that sleeping left-side down with the head/torso elevated reduces recumbent gastroesophageal reflux (GER).

BACKGROUND

Previous studies show that sleeping with head of bed elevated or on wedge reduces GER and lying left-side down reduces GER versus right-side down and supine. No prior studies have evaluated the potential compounding effects of lying in an inclined position combined with lateral positioning on GER.

STUDY

We evaluated a sleep-positioning device (SPD) consisting of an inclined base and body pillow that maintains lateral position while elevating the head/torso. This was a single institution, randomized controlled trial involving 20 healthy volunteers receiving 4 six-hour impedance-pH tests. After placement of reflux probe, subjects returned home, ate standardized meal, and lay down in randomly assigned positions: SPD right-side down (SPD-R), SPD left-side down (SPD-L), standard wedge any position (W), or flat any position (F). A wireless accelerometer documented position during each study. Number of reflux episodes (RE) and esophageal acid exposure (EAE) were calculated over 6 hours.

RESULTS

Significantly less EAE occurred during sleeping SPD-L versus sleeping W, SPD-R, and F. The most EAE occurred during sleeping SPD-R despite use of the positioning device. RE were significantly less SPD-L than SPD-R. Patients sleeping SPD-L and SPD-R spent the majority of first 2 hours and greater than half of 6 hours in assigned position. Patients sleeping W and F averaged more time supine than right or left.

CONCLUSIONS

The sleep positioning device maintains recumbent position effectively. Lying left-side down, it reduces recumbent esophageal acid exposure.