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.

Unsedated transnasal endoscopy with ultrathin endoscope as a screening tool for research studies.

OBJECTIVES/HYPOTHESIS: Asymptomatic subjects volunteering for research studies are generally stratified as healthy based on a questionnaire, medical interviewing, and physical examination. The aim of this study was to evaluate the prevalence of upper gastrointestinal (GI) abnormalities in healthy asymptomatic volunteers using unsedated transnasal esophagogastroduodenoscopy (T-EGD) with an ultrathin endoscope as an additional screening tool. STUDY DESIGN: A prospective study from one academic medical center with extensive experience in T-EGD. METHODS: Consecutive 150 subjects volunteering for research studies were initially screened by using a gastroesophageal reflux disease (GERD) questionnaire, interviewing, and examination. Based on these, they were stratified as healthy asymptomatic volunteers or with GERD. Unsedated T-EGD was then performed by a faculty member who was blinded to the results of the initial assessment. RESULTS: On initial assessment using GERD questionnaire, medical interviewing, and physical examination, of the total 150 consecutive research volunteers, 83 (average age 33 ± 16 years; 46 females, 37 males) subjects were healthy asymptomatic volunteers and 67 (average age 36 ± 15 years; 35 females, 32 males) had symptoms of GERD. On T-EGD, GI pathology was found in 15 of 83 (18%) healthy asymptomatic volunteers as compared to 24 of 67 (36%) stratified as having GERD (P < .01). The esophageal abnormalities found in healthy asymptomatic volunteers were esophagitis (13.3%), Barrett's esophagus (2.4%), hiatus hernia (2.4%), and gastritis (2.4%). CONCLUSIONS: A small but significant number of asymptomatic subjects have abnormal upper GI findings. Hence, transnasal unsedated endoscopy can be considered as a screening tool to stratify subjects as healthy, especially when considering them for research studies.

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.