Effect of systemic alcohol and nicotine on airway protective reflexes

A predictive model for swallowing dysfunction after oral cancer resection

Aggressive therapy of oral cancers is associated with significant postoperative morbidity. Patients with feeding issues may require nutritional support. In our unit, patients identified as developing feeding issues are reactively referred for specialist input through a feeding issues multidisciplinary team meeting (FiMDT). Reactive feeding increases length of patient stay (LOS) and may contribute to patient morbidity. We aimed to develop a model to pre-emptively identify patients likely to develop feeding issues postoperatively, to facilitate the establishment of a preoperative referral pathway to increase patient flow. All referrals to a Head and Neck multidisciplinary team meeting over a five-year period were identified and preoperative factors were extracted. Linear regression was used to confirm that FiMDT was an independent predictor of LOS. Logistic regression was used to determine if referral to FiMDT could be predicted based on preoperative factors only. A total of 203 patients met inclusion criteria for analysis. Inpatient referral to FiMDT was an independent predictor of LOS. Significant predictors of inpatient FiMDT referral included tracheostomy, patient age, and alcohol intake. The resulting model was 90% sensitive and 93.8% specific with a threshold of 0.2. We have shown that inpatient FiMDT referral is an independent predictor of patient length of stay, and that the odds of referral can be robustly predicted. We aim to use this model in redirecting emphasis to a preoperative referral pathway for improved patient flow.

[Intraoperative Aspiration]

术中误吸是外科手术中常见的肺部并发症，麻醉和体位是导致术中误吸的主要因素。近年来，围手术期肺保护已受到外科和麻醉医师的广泛关注，如何加速术后康复进程，减少相关并发症发生，显著改善患者预后已成为当前外科治疗的主要目标。本文将以术中误吸为重点，从解剖、病理生理、表现、诊断、处理和预防等方面展开综述。

Unsuspected Critical Illness Among Emergency Department Patients Presenting for Acute Alcohol Intoxication

STUDY OBJECTIVE

Emergency department (ED) visits for acute alcohol intoxication are common, but this population is at risk for decompensation and occult critical illness. The purpose of this study is to describe the incidence and predictors of unsuspected critical illness among patients with acute alcohol intoxication.

METHODS

This was a retrospective observational study of ED patients from 2011 to 2016 with acute alcohol intoxication. The study cohort included patients presenting for alcohol intoxication, whose initial assessment was uncomplicated alcohol intoxication without any other active acute medical or traumatic complaints. The primary outcome was defined as the unanticipated subsequent use of critical care resources during the encounter or admission to an ICU. We investigated potential predictors for this outcome with generalized estimating equations.

RESULTS

We identified 31,364 eligible patient encounters (median age 38 years; 71% men; median breath alcohol concentration 234 mg/dL); 325 encounters (1%) used critical care resources. The most common diagnoses per 1,000 ED encounters were acute hypoxic respiratory failure (3.1), alcohol withdrawal (1.7), sepsis or infection (1.1), and intracranial hemorrhage (1.0). Three patients sustained a cardiac arrest. Presence of the following had an increased adjusted odds ratio (aOR) of developing critical illness: hypoglycemia (aOR 9.2), hypotension (aOR 3.8), tachycardia (aOR 1.8), fever (aOR 7.6), hypoxia (aOR 3.8), hypothermia (aOR 4.2), and parenteral sedation (aOR 2.4). The initial blood alcohol concentration aOR was 1.0.

CONCLUSION

Critical care resources were used for 1% of ED patients with alcohol intoxication who were initially assessed by physicians to have low risk. Abnormal vital signs, hypoglycemia, and chemical sedation were associated with increased odds of critical illness.

Maturation Modulates Pharyngeal-Stimulus Provoked Pharyngeal and Respiratory Rhythms in Human Infants

Pharyngeal-provocation induced aerodigestive symptoms in infants remain an enigma. Sources of pharyngeal provocation can be anterograde as with feeding, and retrograde as in gastroesophageal reflux. We determined maturational and dose-response effects of targeted pharyngeal-stimulus on frequency, stability, and magnitude of pharyngeal and respiratory waveforms during multiple pharyngeal swallowing responses in preterm-born infants when they were of full-term postmenstrual age (PMA). Eighteen infants (11 male) were studied longitudinally at 39.8 ± 4.8 weeks PMA (time-1) and 44.1 ± 5.8 weeks PMA (time-2). Infants underwent concurrent pharyngo-esophageal manometry, respiratory inductance plethysmography, and nasal airflow thermistor methods to test sensory-motor interactions between the pharynx, esophagus, and airway. Linear mixed models were used and data presented as mean ± SEM or %. Overall, responses to 250 stimuli were analyzed. Of the multiple pharyngeal swallowing responses (n = 160), with maturation (a) deglutition apnea duration decreases (p < 0.01), (b) number of pharyngeal waveform peaks and duration decreases for initial responses (p < 0.01), and subsequent responses have lesser variation and greater stability (p < 0.01). With increment in stimulus volumes we noted (a) increased prevalence (%) of pharyngeal responses (p < 0.05), (b) increased number of pharyngeal peaks (p < 0.05), yet pharyngeal frequency (Hz), variability, and stability remain unaffected (p > 0.05), and (c) respiratory changes were unaffected (p > 0.05). Initial and subsequent pharyngeal responses and respiratory rhythm interactions become more distinct with maturation. Interval oromotor experiences and volume-dependent increase in adaptive responses may be contributory. These mechanisms may be important in modulating and restoring respiratory rhythm normalcy.

Overstimulation of the inhibitory nervous system plays a role in the pathogenesis of neuromuscular and neurological diseases: a novel hypothesis

Based upon a thorough review of published clinical observations regarding the inhibitory system, I hypothesize that this system may play a key role in the pathogenesis of a variety of neuromuscular and neurological diseases. Specifically, excitatory overstimulation, which is commonly reported in neuromuscular and neurological diseases, may be a homeostatic response to inhibitory overstimulation. Involvement of the inhibitory system in disease pathogenesis is highly relevant, given that most approaches currently being developed for treating neuromuscular and neurological diseases focus on reducing excitatory activity rather than reducing inhibitory activity.

Upper gastrointestinal motility: prenatal development and problems in infancy

Deglutition, or swallowing, refers to the process of propulsion of a food bolus from the mouth into the stomach and involves the highly coordinated interplay of swallowing and breathing. At 34 weeks gestational age most neonates are capable of successful oral feeding if born at this time; however, the maturation of respiration is still in progress at this stage. Infants can experience congenital and developmental pharyngeal and/or gastrointestinal motility disorders, which might manifest clinically as gastro-oesophageal reflux (GER) symptoms, feeding difficulties and/or refusal, choking episodes and airway changes secondary to micro or overt aspiration. These problems might lead to impaired nutritional intake and failure to thrive. These gastrointestinal motility disorders are mostly classified according to the phase of swallowing in which they occur, that is, the oral preparatory, oral, pharyngeal and oesophageal phases. GER is a common phenomenon in infancy and is referred to as GERD when it causes troublesome complications. GER is predominantly caused by transient relaxation of the lower oesophageal sphincter. In oesophageal atresia, oesophageal motility disorders develop in almost all patients after surgery; however, a congenital origin of disordered motility has also been proposed. This Review highlights the prenatal development of upper gastrointestinal motility and describes the most common motility disorders that occur in early infancy.

Effect of aging on hypopharyngeal safe volume and the aerodigestive reflexes protecting the airways

OBJECTIVES/HYPOTHESIS

Studies on young volunteers have shown that aerodigestive reflexes are triggered before the maximum volume of fluid that can safely collect in the hypopharynx before spilling into the larynx is exceeded (hypopharyngeal safe volume [HPSV]). The objective of this study was to determine the influence of aging on HPSV and pharyngo-glottal closure reflex (PGCR), pharyngo-UES contractile reflex (PUCR), and reflexive pharyngeal swallow (RPS).

STUDY DESIGN

Comparison between two groups of different age ranges.

METHODS

Ten young (25 ± 3 standard deviation [SD] years) and 10 elderly (77 ± 3 SD years) subjects were studied. PGCR, PUCR, and RPS were elicited by perfusing water into the pharynx rapidly and slowly. HPSV was determined by abolishing RPS with pharyngeal anesthesia.

RESULTS

Frequency-elicitation of PGCR and PUCR were significantly lower in the elderly compared to the young during slow water perfusion (47% vs. 97% and 40% vs. 90%, respectively, P < .001). RPS was absent in five of the 30 (17%) slow injections in the elderly group. In these elderly subjects, HPSV was exceeded and laryngeal penetration of the water was seen. The threshold volume to elicit PGCR, PUCR, and RPS was significantly lower than the HPSV during rapid injections. Except for RPS, these volumes were also significantly lower than HPSV during slow injections.

CONCLUSIONS

PGCR, PUCR, and RPS reflexes are triggered at a threshold volume significantly lower than the HPSV in both young and elderly subjects. Lower frequency-elicitation of PGCR, PUCR, and RPS in the elderly can predispose them to the risks of aspiration.

Fatalities Due to Choking: Internal Occlusion of Airway

Deaths due to internal obstructions of the airway (choking) are preventable injuries that are often associated with underlying risk factors including neurologic impairment by disease, intoxication, or very young or old age.

We reviewed 138 decedents with accidental internal obstruction of the airway. Records including autopsy, toxicology, and investigators’ reports were reviewed for a five-year period. There were 138 choking deaths and the age ranged from one to 96 years (mean = 57). Neurologic disease (e.g., remote cerebral vascular events, dementia, developmental disorders) was the most common risk factor for fatal choking (51%), followed by acute alcohol intoxication (13%), psychiatric illness (8%), and young age (8%). In 8% of decedents, there was no identifiable risk factor following investigation, autopsy, and toxicological examinations. The choking episode most commonly occurred in residences (62%), followed by nursing home/long-term care facilities (20%), streets/parks (6%), restaurants/bars (4%), and schools (1%, including one culinary school). Meat was the most commonly identified food object (14%); non-food objects included drug packets.

It is exceedingly rare for a neurologically intact adult to choke to death on a bolus of food without another underlying, identifiable risk factor. For death investigation, it is important to have a high index of suspicion for choking, and one must be careful not to confuse terminal aspiration of gastric contents with a fatal blockage of the airway by a swallowed bolus of food. A risk factor should be sought in each choking death, as it usually is the underlying cause of death.

The effect of unilateral superior laryngeal nerve lesion on swallowing threshold volume

OBJECTIVES/HYPOTHESIS

The superior laryngeal nerve (SLN) is the major sensory nerve for the upper larynx. Damage to this nerve impacts successful swallowing. The first aim of the study was to assess the effect of unilateral SLN lesion on the threshold volume sufficient to elicit swallowing in an intact pig model; this volume was defined radiographically as the maximum bolus area visible in lateral view. The second aim was to determine if a difference existed between ipsilateral and contralateral function as a result of unilateral sensory loss, measured as the radiologic density of fluid seen in the valleculae. Finally, we determined whether there was a relationship between the threshold volume and the occurrence of aspiration after a unilateral SLN lesion.

STUDY DESIGN

Repeated measures animal study.

METHODS

Four female infant pigs underwent unilateral SLN lesion surgery. The maximum vallecular bolus area in lateral view and the relative vallecular density on each side in the dorsoventral view were obtained from videofluoroscopic recordings in both the prelesion control and postlesion experimental states.

RESULTS

In lateral view, the lesioned group had a larger maximum bolus area than the control group (P < .001). Although occasional left-right asymmetry in the dorsoventral view was observed, the vallecular densities were, on average, equal on both the left (intact) and right (lesioned) sides (P > .05). A bigger maximum bolus area did not predict aspiration in the lesioned group (P > .05).

CONCLUSIONS

Unilateral SLN lesions increased the swallowing threshold volume symmetrically in right and left valleculae, but the increased threshold may not be the main mechanism for the occurrence of aspiration.

Characterization of the upper esophageal sphincter response during cough

BACKGROUND

Vagal reflex initiated by esophageal stimulation and microaspiration can cause chronic cough in patients with gastroesophageal reflux disease (GERD). By raising intraabdominal pressure,cough can, in turn, predispose to GERD. The role of the upper esophageal sphincter (UES)in preventing esophagopharyngeal reflux during coughing is not well known. The aim of this study was to evaluate the UES response during coughing.

METHODS

We studied 20 healthy young (10 women; age, 27 ± 5 years) and 15 healthy elderly(nine women; age, 73 ± 4 years) subjects. Hard and soft cough-induced pressure changes in the UES, distal esophagus, lower esophageal sphincter, and stomach were determined simultaneously using high-resolution manometry and concurrent acoustic cough recordings.

RESULTS

Resting UES pressure was significantly higher in the young compared with the elderly subjects (42 ± 14 mm Hg vs 24 ± 9 mm Hg; P < .001). Cough induced a UES contractile response in all subjects. Despite lower UES resting pressures in the elderly subjects, the maximum UES pressure during cough was similar between the young and the elderly subjects (hard cough, 230 ± 107 mm Hg vs 278 ± 125 mm Hg, respectively; soft cough, 156 ± 85 mm Hg vs 164 ± 119 mm Hg, respectively; P not significant for both). The UES pressure increase over baseline during cough was significantly higher than that in the esophagus, lower esophageal sphincter, and stomach for both groups ( P < .001).

CONCLUSIONS

Cough induces a rise in UES pressure, and this response is preserved in elderly people. A cough-induced rise in UES pressure is significantly higher than that in the esophagus and stomach,thereby providing a barrier against retrograde entry of gastric contents into the pharynx.

Effects of postnatal environmental tobacco smoke on non-nutritive swallowing-breathing coordination in newborn lambs

While prenatal environmental tobacco smoke (ETS) exposure is a well-known risk factor for sudden infant death syndrome, the effect of postnatal ETS exposure is less clear. The objective of this study was to investigate the effect of postnatal ETS exposure on non-nutritive swallowing (NNS) and NNS-breathing coordination, which are crucial to prevent aspiration related-cardiorespiratory events. Eighteen newborn lambs (6 per group) were randomly exposed to either 10 cigarettes/day, 20 cigarettes/day or room air for 15 days. Lambs were instrumented for recording states of alertness, swallowing, electrocardiogram and breathing; recordings were performed in non-sedated lambs at the end of ETS exposure. Urinary cotinine/creatinine ratio confirmed relevant real-life exposure. Postnatal ETS exposure had no effect on NNS frequency but tended to decrease inspiratory NNS (p=0.07) during quiet sleep. No effect on respiratory or heart rate (p>0.6), apnea index (p=0.2) or sleep states (p=0.3) was observed. In conclusion, postnatal ETS exposure in lambs had only mild effects on NNS-breathing coordination.

Pharyngeal airway protective reflexes are triggered before the maximum volume of fluid that the hypopharynx can safely hold is exceeded

Aerodigestive reflexes triggered by pharyngeal stimulation can protect the airways by clearing fluid from the pharynx. The objective of this study was to determine the relationship between the maximum capacity of fluid that can safely dwell in the hypopharynx [hypopharyngeal safe volume (HPSV)] before spilling into the larynx and the threshold volumes required to trigger pharyngoglottal closure reflex (PGCR), pharyngo-upper esophageal sphincter contractile reflex (PUCR), and reflexive pharyngeal swallow (RPS). Twenty-five healthy volunteers (mean age 24 yr, 8 males) were studied in the semi-inclined supine position. PGCR, PUCR, and RPS were elicited using techniques of concurrent upper esophageal sphincter manometry and pharyngo-laryngoscopy. The hypopharynx was then anesthetized to abolish RPS. HPSV was determined by infusing water in the pharynx, and perfusion was stopped when the infusate reached the superior margin of the interarytenoid fold. The threshold volumes for triggering PGCR, PUCR, and RPS by slow and rapid injections before pharyngeal anesthesia were 0.18 ± 0.02 and 0.09 ± 0.02 ml; 0.20 ± 0.020 and 0.13 ± 0.04 ml; and 0.61 ± 0.04 and 0.4 ± 0.06 ml, respectively. All of the above volumes were significantly smaller than the HPSV (0.70 ± 0.06 ml, P < 0.01) except for the threshold volume to elicit RPS during slow perfusion, which was not significantly different (P = 0.23). We conclude that pharyngeal aerodigestive reflexes are triggered by both slow and rapid pharyngeal perfusion of water at significantly smaller volumes than the maximum capacity of the hypopharynx to safely hold contents without spilling into the airway. These reflexes thereby aid in prevention of aspiration.

Protective role of aerodigestive reflexes against aspiration: study on subjects with impaired and preserved reflexes

BACKGROUND & AIMS

Direct evidence to support the airway protective function of aerodigestive reflexes triggered by pharyngeal stimulation was previously demonstrated by abolishing these reflexes by topical pharyngeal anesthesia in normal subjects. Studies have also shown that these reflexes deteriorate in cigarette smokers. Aim of this study was to determine the influence of defective pharyngeal aerodigestive reflexes on airway protection in cigarette smokers.

METHODS

Pharyngoglottal Closure reflex; PGCR, Pharyngo-UES Contractile reflex; PUCR, and Reflexive Pharyngeal Swallow; RPS were studied in 15 healthy non-smokers (24.2±3.3 SD y, 7 males) and 15 healthy chronic smokers (27.3±8.1, 7 males). To elicit these reflexes and to evaluate aspiration, colored water was perfused into the hypopharynx at the rate of 1 mL/min. Maximum volume of water that can safely dwell in the hypopharynx before spilling into the larynx (Hypopharyngeal Safe Volume; HPSV) and the threshold volume to elicit PGCR, PUCR, and RPS were determined in smokers and results compared with non-smokers.

RESULTS

At baseline, RPS was elicited in all non-smokers (100%) and in only 3 of 15 smokers (20%; P<.001). None of the non-smokers showed evidence of laryngeal spillage of water, whereas 12 of 15 smokers with absent RPS had laryngeal spillage. Pharyngeal anesthesia abolished RPS reflex in all non-smokers resulting in laryngeal spillage. The HPSV was 0.61±0.06 mL and 0.76±0.06 mL in non-smokers and smokers respectively (P=.1).

CONCLUSIONS

Deteriorated reflexive pharyngeal swallow in chronic cigarette smokers predispose them to risks of aspiration and similarly, abolishing this reflex in non-smokers also results in laryngeal spillage. These observations directly demonstrate the airway protective function of RPS.

Diagnosis and management of oropharyngeal Dysphagia and its nutritional and respiratory complications in the elderly

Oropharyngeal dysphagia is a major complaint among older people. Dysphagia may cause two types of complications in these patients: (a) a decrease in the efficacy of deglutition leading to malnutrition and dehydration, (b) a decrease in deglutition safety, leading to tracheobronchial aspiration which results in aspiration pneumonia and can lead to death. Clinical screening methods should be used to identify older people with oropharyngeal dysphagia and to identify those patients who are at risk of aspiration. Videofluoroscopy (VFS) is the gold standard to study the oral and pharyngeal mechanisms of dysphagia in older patients. Up to 30% of older patients with dysphagia present aspiration-half of them without cough, and 45%, oropharyngeal residue; and 55% older patients with dysphagia are at risk of malnutrition. Treatment with dietetic changes in bolus volume and viscosity, as well as rehabilitation procedures can improve deglutition and prevent nutritional and respiratory complications in older patients. Diagnosis and management of oropharyngeal dysphagia need a multidisciplinary approach.