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Biomedical subjects

Reza Shaker

Publications and source records attributed to Reza Shaker.

At least 19 recordsLinked to original sources
PubMed2007

Impedance signature of pharyngeal gaseous reflux.

BACKGROUND: Pharyngeal impedance changes induced by various pharyngeal reflux events have not been characterized. OBJECTIVES: To characterize pharyngeal impedance changes induced by participant-perceived belching events. METHODS: We systematically evaluated pharyngeal impedance and pH changes related to 453 belch events in 11 gastroesophageal reflux disease, 10 reflux attributed-laryngitis patients and 16 controls. RESULTS: Of 453 belch events, 362 were analyzable. Of these, 72% occurred within 10 s, 93% within 20 s, 99% within 30 s and 100% within 40 s of the time that participants marked a belch event. In 15% impedance changes in the pharynx preceded, in 12% they were simultaneous and in 73% they occurred after the start of the impedance change in the proximal esophagus. Time interval between the two events ranged between 0.4+/-0.03 and 0.7+/-0.1 s. In all, there were three types of belch-induced impedance changes: (a) impedance increase, (b) impedance decrease and (c) multiphasic. Twenty percent of impedance events associated with belching had less than 50% change from baseline, whereas in 51% changes exceeded or were equal to 50%. Among events with a drop in pharyngeal impedance, only two satisfied the criteria for the liquid reflux event. CONCLUSIONS: Pharyngeal ventilation of gastric gaseous content seems to have a unique impedance signature. During pharyngeal gas reflux events, impedance changes may start before or after proximal esophageal changes. Belching may induce negative pharyngeal changes that do not meet the criteria for liquid reflux. These findings need to be taken into consideration in the analysis of pharyngeal reflux events.

Adult↗
PubMed2006

Human esophageal microvascular endothelial cells respond to acidic pH stress by PI3K/AKT and p38 MAPK-regulated induction of Hsp70 and Hsp27.

The heat shock response maintains cellular homeostasis following sublethal injury. Heat shock proteins (Hsps) are induced by thermal, oxyradical, and inflammatory stress, and they chaperone denatured intracellular proteins. Hsps also chaperone signal transduction proteins, modulating signaling cascades during repeated stress. Gastroesophageal reflux disease (GERD) affects 7% of the US population, and it is linked to prolonged esophageal acid exposure. GERD is characterized by enhanced and selective leukocyte recruitment from esophageal microvasculature, implying activation of microvascular endothelium. We investigated whether phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK regulate Hsp induction in primary cultures of human esophageal microvascular endothelial cells (HEMEC) in response to acid exposure (pH 4.5). Inhibitors of signaling pathways were used to define the contribution of PI3K/Akt and MAPKs in the heat shock response and following acid exposure. Acid significantly enhanced phosphorylation of Akt and MAPKs in HEMEC as well as inducing Hsp27 and Hsp70. The PI3K inhibitor LY-294002, and Akt small interfering RNA inhibited Akt activation and Hsp70 expression in HEMEC. The p38 MAPK inhibitor (SB-203580) and p38 MAPK siRNA blocked Hsp27 and Hsp70 mRNA induction, suggesting a role for MAPKs in the HEMEC heat shock response. Thus acidic pH exposure protects HEMEC through induction of Hsps and activation of MAPK and PI3 kinase pathway. Acidic exposure increased HEMEC expression of VCAM-1 protein, but not ICAM-1, which may contribute to selective leukocyte (i.e., eosinophil) recruitment in esophagitis. Activation of esophageal endothelial cells exposed to acidic refluxate may contribute to GERD in the setting of a disturbed mucosal squamous epithelial barrier (i.e., erosive esophagitis, peptic ulceration).

Actins↗
PubMed2006

Neonatal nociceptive somatic stimulation differentially modifies the activity of spinal neurons in rats and results in altered somatic and visceral sensation.

The role ofintramuscular, low pH saline injections during the neonatal period in the development and maintenance of visceral hyperalgesia has not been systematically studied. We aimed to investigate alterations in visceral sensation and neural circuitry that result from noxious stimuli in early life. Neonatal male Sprague-Dawley rats received sterile saline injections of pH 4.0 or 7.4 in the gastrocnemius muscle starting at postnatal day 8. Injections were given unilaterally every other day for 12 days ending on postnatal day 20. A third group received needle prick only on the same shedule as the second group, while a fourth group was left naïve. At 2 months of age, rats underwent assessment of cutaneous and deep somatic sensitivity using von Frey filaments and gastrocnemius muscle pinch, respectively. A visceromotor response (VMR) to graded colorectal distension (CRD; 10-80 mmHg for 30 s with 180 s interstimulus intervals) was recorded. Extracellular single-unit recordings from the thoracolumbar spinal neurons (T13-L1) were performed in adult pH 4.0 injected and naïve controls. There was no difference in the threshold for response to mechanical stimulation of the paw in rats injected with pH 4.0 saline compared to all other groups. Conversely, rats treated with pH 4.0 saline showed a significant bilateral reduction in withdrawal threshold to muscle pinch as adults (P < 0.05). At colorectal distensions > or = 20 mmHg, an increase in the VMR was observed in the pH 4.0 injected group compared to all other groups (P < 0.05). Spinal neurons were classified as short latency abrupt (SL-A) or short latency sustained (SL-S). Spontaneous firing of SL-S (20.6 +/- 2.2 impulses s(-1)), but not SL-A neurons (5.3 +/- 0.9 impulses s(-1)) in the pH 4.0 treated rats was significantly higher than in control rats (SL-S, 2.6 +/- 0.8 impulses s(-1); SL-A, 3.1 +/- 0.7 impulses s(-1)). The response of SL-S neurons to CRD in the pH 4.0 group was significantly higher at distension pressures > or = 20 mmHg. Nociceptive somatic stimulation in neonatal rats results in chronic deep somatic and visceral hyperalgesia in adulthood. Colorectal distension-sensitive SL-S neurons are primarily sensitized to neonatal somatic stimulation.

Action Potentials↗
PubMed2006

Correlation of glottal closure using concurrent ultrasonography and nasolaryngoscopy in children: a novel approach to evaluate glottal status.

OBJECTIVES: Endoscopic procedures to assess aerodigestive symptoms by evaluating glottal motion are not practical in neonates because of small nares, respiratory difficulties, or additional stress. Our objective was to determine the temporal correlation between concurrent nasolaryngoscopy (NLS) and ultrasonography (USG) evaluation of glottal motion. METHODS: Simultaneous USG of the glottis was performed in 10 subjects (5 males, 5 females, age = 4.5 months to 7.1 years) that underwent diagnostic flexible outpatient NLS. The USG transducer was placed on the anterior neck at the level of the vocal cords. The video signals from NLS and USG were integrated and synchronized into real-time cine loops of 1-min duration. RESULTS: Frame-by-frame evaluation of 10,800 frames identifying glottal opening and closure time was compared between the two modalities by three observers and the timing of glottal closure was marked. Two investigators, blinded to NLS images, identified ultrasonographically determined glottal closure with 99% and 100% accuracy, and the mean probability of missing a closure frame was 0.007 (95% CI = 0.0008-0.024). CONCLUSIONS: Temporal characteristics of glottal motion can be quantified by USG with perfect reliability and safety. This method can be useful in measuring the presence and the duration of laryngeal adduction.

Child↗
PubMed2006

Effect of maturation of the magnitude of mechanosensitive and chemosensitive reflexes in the premature human esophagus.

OBJECTIVES: To investigate the effect of esophageal mechanosensitive and chemosensitive stimulation on the magnitude and recruitment of peristaltic reflexes and upper esophageal sphincter (UES)-contractile reflex in premature infants. STUDY DESIGN: Esophageal manometry and provocation testing were performed in the same 18 neonates at 33 and 36 weeks postmenstrual age (PMA). Mechanoreceptor and chemoreceptor stimulation were performed using graded volumes of air, water, and apple juice (pH 3.7), respectively. The frequency and magnitude of the resulting esophago-deglutition response (EDR) or secondary peristalsis (SP), and esophago-UES-contractile reflex (EUCR) were quantified. RESULTS: Threshold volumes to evoke EDR, SP, or EUCR were similar. The recruitment and magnitude of SP and EUCR increased with volume increments of air and water in either study (P < .05). However, apple juice infusions resulted in increased recruitment of EDR in the 33 weeks group (P < .05), and SP in the 36 weeks group (P < .05). The magnitude of EUCR was also volume responsive (all media, P < .05), and significant differences between media were noted (P < .05). At maximal stimulation (1 mL, all media), sensory-motor characteristics of peristaltic and EUCR reflexes were different (P < .05) between media and groups. CONCLUSIONS: Mechano- and chemosensitive stimuli evoke volume-dependent specific peristaltic and UES reflexes at 33 and 36 weeks PMA. The recruitment and magnitude of these reflexes are dependent on the physicochemical properties of the stimuli in healthy premature infants.

Air↗
PubMed2006

Influence of sleep stages on esophago-upper esophageal sphincter contractile reflex and secondary esophageal peristalsis.

BACKGROUND & AIMS: Airways are most vulnerable to aspiration during sleep. Esophago-upper esophageal sphincter (UES) contractile reflex (EUCR) and secondary peristalsis (2P) have been proposed to protect the airway by reflexively contracting the UES and clearing the esophagus of refluxate, respectively. Our aim was to study EUCR and 2P elicitation in "awake" state, stage II, slow-wave (stage III/IV), and rapid eye movement (REM) sleep. METHODS: Thirteen healthy volunteers were studied in the supine position using concurrent UES and esophageal manometry and polysomnography. Threshold volume (Tvol) to trigger EUCR and 2P and changes in sleep stages were recorded during injection of 2.7 mL/min water into the proximal esophagus after sleep stages were confirmed. RESULTS: UES pressure progressively declined with deeper stages of sleep. Tvol for EUCR and 2P elicitation was not significantly different between the stage II and "awake" state (EUCR: 4.0 +/- 1.8 mL vs 6.1 +/- 3.6 mL stage II; 2P: 5.8 +/- 2.2 mL vs 8.0 +/- 4.0 mL stage II). Tvol for EUCR and 2P elicitation during REM sleep were significantly lower than during the stage II and "awake" state (REM EUCR: 2.2 +/- 1.1 mL; 2P: 3.5 +/- 1.2 mL). Arousal and cough preempted development of EUCR and 2P during slow-wave sleep. CONCLUSIONS: (1) EUCR/2P can be elicited in stage II and REM but is preempted by arousal in slow-wave sleep. (2) Tvol for EUCR/2P elicitation is significantly lower in REM, compared with the stage II and "awake" state, suggesting a heightened sensitivity of these reflexes during REM sleep. (3) Although UES pressure progressively declines with deeper stages of sleep, it can still reflexively contract during REM sleep, despite generalized hypotonia.

Adult↗
PubMed2006

Novel evidence for hypersensitivity of visceral sensory neural circuitry in irritable bowel syndrome patients.

BACKGROUND & AIMS: Visceral hypersensitivity in irritable bowel syndrome (IBS) patients has been documented by evaluation of perceived stimulations that can reflect abnormalities of both sensory neurocircuitry and cognitive processes. The presence of actual neurohypersensitivity in human beings has not been documented separately. Because subliminal stimulations are free from the influence of stimulus-related cognitive processes, functional magnetic resonance imaging (fMRI) cortical response to these stimuli can be considered a measure of activity of the neural circuitry alone. The aim of this study was to compare quantitatively the cerebral cortical fMRI activity response to equal subliminal stimulations between IBS patients and age-matched controls. METHODS: We studied 10 IBS patients and 10 healthy controls using a computerized barostat-controlled rectal distention device. fMRI activity volume and percent maximum signal intensity change for equal subliminal distention pressures were compared between controls and patients. RESULTS: Three levels of subliminal distention pressures (eg, 10, 15, and 20 mm Hg), were represented in both controls and patients and were analyzed for fMRI response. In all 3 distention levels the fMRI activity volume in IBS patients was significantly larger than age- and sex-matched controls (P < .05). The percent maximum signal intensity change was similar between IBS patients and controls. CONCLUSIONS: The volume of cerebral cortical activity response to equal subliminal distention pressures in IBS patients is significantly larger than in controls, documenting the existence of hypersensitivity of the neural circuitry in this patient group irrespective of stimulus-related cognitive processes.

Adult↗
PubMed2006

Treatment of chronic posterior laryngitis with esomeprazole.

OBJECTIVE: To evaluate the efficacy of acid-suppressive therapy with the proton pump inhibitor esomeprazole on the signs and symptoms of chronic posterior laryngitis (CPL) in patients with suspected reflux laryngitis. STUDY DESIGN: Prospective, multicenter, randomized, parallel-group trial that compared twice-daily esomeprazole 40 mg with placebo for 16 weeks. METHODS: Eligible patients had a history of one or more CPL symptoms (throat clearing, cough, globus, sore throat, or hoarseness) and laryngoscopic signs indicating reflux laryngitis based on CPL index (CPLI) scores measured during a screening laryngoscopy. Patients were randomized to treatment if their 7-day screening diary-card recordings showed a cumulative primary symptom score of 9 or higher and they had 3 or more days with moderately severe symptoms based on a 7-point scale. Efficacy was assessed by changes in symptoms as recorded by patients and investigators and by changes in CPLI scores based on laryngoscopic examinations. RESULTS: The patients' primary CPL symptom at final visit (primary efficacy end point) was resolved in 14.7% (14/95) and 16.0% (8/50) of patients in the esomeprazole and placebo groups, respectively (P=.799). Esomeprazole and placebo were not significantly different for change from baseline to the final visit in mean total CPLI (-1.66+/-2.13 vs. -2.0+/-2.55, respectively; P=.446) or any other secondary efficacy end points based on patient diary card or investigator assessments. CONCLUSION: This study provides no evidence of a therapeutic benefit of treatment with esomeprazole 40 mg twice daily for 16 weeks compared with placebo for signs and symptoms associated with CPL.

Adult↗
PubMed2006

Dickkopf homologs in squamous mucosa of esophagitis patients are overexpressed compared with Barrett's patients and healthy controls.

OBJECTIVES: Esophageal mucosal response to acid exposure varies from minimal changes to erosions/ulcerations and Barrett's metaplasia. While differences in acid contact time have been suggested, the reason for these different responses is not completely understood. The aim of this study was to identify and compare gene expression differences between normal distal and proximal squamous esophageal mucosa (SM) in esophagitis patients with that of healthy controls and Barrett's patients. METHODS: Gene microarray was performed on laser-capture microdissected epithelial cells isolated from biopsy specimens followed by real-time PCR. The effect of acidic pH (pH 4.5) on Dickkopf Homolog 1 (Dkk-1) expression in the human esophageal epithelial cell line (Het-1A) was determined. RESULTS: Gene microarray analysis demonstrated that the upregulation of five genes in the distal compared with the proximal SM in esophagitis patients was greater than the healthy controls and Barrett's patients. Overexpression of Dkk-1 and Dkk-4 was further confirmed by real-time PCR. Dkk-1 and Dkk-4 mRNA levels in the distal SM of the esophagitis patients were 7.0- and 3.1-fold higher, respectively, than in the distal SM of the Barrett's patients and 4.1- and 4.1-fold higher than in healthy controls, respectively. Dkk-1 protein expression in the distal esophagitis SM was also higher than the Barrett's patients and healthy controls. Acidic pH exposure of Het-1A cells resulted in Dkk-1 upregulation at the level of both mRNA and protein. CONCLUSIONS: Dkk-1 and Dkk-4 may potentially be involved in the development of different injuries in response to pathological gastroesophageal acid reflux.

Adolescent↗
PubMed2006

Effect of aging on bolus kinematics during the pharyngeal phase of swallowing.

Swallowing difficulty is a common complaint in the elderly and, although there are data for the biomechanics of liquid swallows, little is known about solid bolus motion, or kinematics, in the elderly. The aims of this study were as follows: 1) to characterize and compare solid and liquid bolus kinematics in the elderly and compare the findings with those in young subjects and 2) to correlate bolus kinematics and dynamics. Concurrent manometric-fluoroscopic techniques were used to study eight young and eight elderly subjects. The subjects performed four swallows each of 0.2-cm-diameter solid barium pellets and 5 ml of liquid barium during sagittal fluoroscopy and six-channel pharyngoesophageal manometry. Images were digitized for analysis of kinematic properties such as velocity and acceleration. Dynamic pressures were recorded and coordinated with kinematic events. Image analysis showed that velocity varied as the pellet passed through the hypopharynx, pharynx, and upper esophageal sphincter. In young subjects, pellet kinematics were characterized by two zones of pellet acceleration: one over the tongue base and another as the pellet passed through the upper esophageal sphincter. Although the elderly showed a similar zone of acceleration over the base of the tongue, the second zone of pellet acceleration was not seen. Decreasing pressure gradients immediately distal to the position of the solid pellet and liquid bolus characterized dynamics for all subjects. This decreasing pressure gradient was significantly larger in elderly than in young subjects. Bolus kinematics and dynamics were significantly altered among elderly compared with young subjects. Among these differences were the absence of hypopharyngeal bolus acceleration and a significant increase in the trans-sphincteric pressure gradient in the elderly.

Adolescent↗
PubMed2005

The effects of volatile salivary acids and bases on exhaled breath condensate pH.

RATIONALE: Recent studies have reported acidification of exhaled breath condensate (EBC) in inflammatory lung diseases. This phenomenon, designated "acidopnea," has been attributed to airway inflammation. OBJECTIVES: To determine whether salivary acids and bases can influence EBC pH in chronic obstructive pulmonary disease (COPD). METHODS: Measurements were made of pH, electrolytes, and volatile bases and acids in saliva and EBC equilibrated with air in 10 healthy subjects and 10 patients. RESULTS: The average EBC pH in COPD was reduced (normal, 7.24 +/- 0.24 SEM; range, 6.11-8.34; COPD, 6.67 +/- 0.18; range, 5.74-7.64; p = 0.079). EBCs were well buffered by NH(4)(+)/NH(3) and CO(2)/HCO(3)(-) in all but four patients, who had NH(4)(+) concentrations under 60 micromol/L, and acetate concentrations that approached or exceeded those of NH(4)(+). Saliva contained high concentrations of acetate (approximately 6,000 micromol/L) and NH(4)(+) (approximately 12,000 micromol/L). EBC acetate increased and EBC NH(4)(+) decreased when salivary pH was low, consistent with a salivary source for these volatile constituents. Nonvolatile acids did not play a significant role in determining pH of condensates because of extreme dilution of respiratory droplets by water vapor (approximately 1:12,000). Transfer of both acetic acid and NH(3) from the saliva to the EBC was in the gas phase rather than droplets. CONCLUSIONS: EBC acidification in COPD can be affected by the balance of volatile salivary acids and bases, suggesting that EBC pH may not be a reliable marker of airway acidification. Salivary acidification may play an important role in acidopnea.

Acetic Acid↗
PubMed2005

Epithelial lining fluid solute concentrations in chronic obstructive lung disease patients and normal subjects.

The exhaled breath condensate (EBC) method represents a new, noninvasive way to detect inflammatory and metabolic markers in the fluid that covers the airways [epithelial lining fluid (ELF)]. However, respiratory droplets represent only a very small and variable fraction of the EBC, most (approximately 99.99%) of which is water vapor. Our objective was to show that ELF concentrations could be calculated from EBC values by using any of three dilutional indicators (urea, total cations, and conductivity) in nine normal and nine chronic obstructive lung disease (COPD) subjects. EBC concentrations of Na(+), K(+), Ca(2+), Mg(2+), total cations, urea, and conductivity varied over a 10-fold range among individuals, but concentrations of these constituents (except Ca(2+)) remained well correlated (r(2) = 0.44-0.83, P < 0.001). Dilution (D) of respiratory droplets in water vapor was calculated by dividing plasma concentrations of the dilutional indicators by EBC concentrations. Estimates of D were not significantly different among these indicators, and urea D averaged 10,800 +/- 2,100 (SE) in normal and 12,600 +/- 3,300 in COPD subjects. Although calculated Na(+) concentrations in the ELF were less than one-half those in plasma, and concentrations of K(+), Ca(2+), and Mg(2+) exceeded those in plasma, total cation concentrations in ELF were not significantly different from those in plasma, indicating that ELF is isotonic in both normal and COPD subjects. EBC amylase concentrations (measured with an ultrasensitive procedure) indicated that saliva represented <10% of the respiratory (ELF) droplets in all but three samples. Dilutional and salivary markers are essential for interpretation of EBC studies.

Aged↗
PubMed2005

Attaining and maintaining isometric and isokinetic goals of the Shaker exercise.

Previous studies have shown that the Shaker Exercise is effective in restoring oral intake in patients with deglutitive failure due to upper esophageal sphincter (UES) dysfunction. Our aim was to determine (1) exerciser compliance among healthy older adults, (2) number of days required to attain the isometric (IM) and isokinetic (IK) exercise goals, (3) rate and reason for dropout of exercisers, and (4) complaints associated with performance of the exercise. Twenty-six nondysphagic older adults were enrolled from an independent-living community (66-93 yr) to perform the Shaker Exercise. Each participant completed a questionnaire on exercise performance and its associated difficulties three times a day for six weeks. Four randomly chosen nondysphagic participants underwent pre- and postexercise videofluoroscopic swallow studies for biomechanical measurements. Maximum anterior hyoid and laryngeal excursions, as well as maximum anteroposterior UES opening increased (p<0.05) following exercise. Duration to attain Shaker Exercise performance goals varied among participants. IK was more easily attained than IM. Only 50% and 70% of those enrolled initially were able to complete the exercise duration and attain its IK and IM goals, respectively. However, those who stayed in the program attained the IK and IM goals (100% and 74%, respectively). Most dropouts occurred in the first two weeks of exercise. Performance of the exercise was associated with mild muscle discomfort that resolved spontaneously after a couple of weeks. We concluded that although the Shaker Exercise can be performed independently, a structured and gradually progressive program is needed to attain the exercise goals completely.

Aged↗
PubMed2005

Swallow syncope in association with Schatzki ring and hypertensive esophageal peristalsis: report of three cases and review of the literature.

Syncope caused by swallowing-induced cardiac arrhythmia is an uncommon condition. The recognition of this syndrome is paramount but often difficult. We report three cases of deglutition syncope evaluated at our institution over a three-year period. Two patients had distal esophageal (Schatzki) ring and two had hypertensive peristaltic waves (commonly referred to as "nutcracker esophagus"), neither of which had been described before in association with deglutition syncope. Two patients underwent placement of a demand cardiac pacemaker with subsequent resolution of their syncopal symptoms, while the third patient refused any further intervention. Swallow syncope usually follows a benign course from a cardiac standpoint. Placement of a demand cardiac pacemaker can prevent recurrence of presyncopal and syncopal attacks and their untoward consequences.

Arrhythmias, Cardiac↗
PubMed2005

Laparoscopic Nissen fundoplication decreases gastroesophageal junction distensibility in patients with gastroesophageal reflux disease.

Laparoscopic Nissen fundoplication (LNF) is the surgical treatment of choice for gastroesophageal reflux disease (GERD). Post-LNF complications, such as gas bloat syndrome, inability to belch and vomit, and dysphagia, remain too common and prevent LNF from being more highly recommended. It remains controversial as to whether preoperative assessment can predict the development of post-LNF complications. Some authors have shown a correlation between pre-LNF manometry characteristics and post-LNF dysphagia, and others have not. We hypothesize that many post-LNF complications are caused by a decrease in the distensibility of the GEJ and that standard manometry is at best an indirect measure of this. The aim of this study is to directly measure the effect of LNF on gastroesophageal junction (GEJ) distensibility (GEJD). The lower esophageal sphincter (LES) of 15 patients undergoing LNF was characterized using standard manometry. The GEJD before and after a standardized LNF was measured using a specialized catheter, containing an infinitely compliant bag, placed within the LES. GEJD was measured, as dV/dP over volumes 5 to 25 mL distended at a rate of 20 mL/min. Mean dP +/- standard error of the mean for each volume was calculated, and distensibility curves were generated and compared. Measurements were also taken after abolishing LES tone by mid-esophageal balloon distension. Patient symptoms were recorded before and after surgery. Statistical analysis was performed by two-way repeated-measures analysis of variance, paired t test, and the Tukey test. Laparoscopic Nissen fundoplication led to a statistically significant increase in Delta pressure over each volume tested and therefore a significant decrease in the distensibility of the GEJ. Abolition of LES tone had no statistical effect on GEJD after fundoplication. There were no complications, and none of the patients developed the symptom of dysphagia postoperatively. These are the first direct measurements to show that LNF significantly reduces the distensibility of the GEJ. We hypothesize that the magnitude of this reduction may be the vital variable in the development of post-LNF complications and specifically post-LNF dysphagia. The intraoperative measurement of LES distensibility may provide a means for avoiding this feared and other post-LNF complications in the future.

Adult↗
PubMed2005

Utility of exhaled breath condensates in chronic obstructive pulmonary disease: a critical review.

PURPOSE OF REVIEW: Evaluation of the utility of exhaled breath condensates in chronic obstructive pulmonary disease. RECENT FINDINGS: Exhaled breath condensates have recently been introduced as a simple, noninvasive method of sampling respiratory fluid in inflammatory lung disorders, including chronic obstructive pulmonary disease. Increases in condensate concentrations of at least 12 markers of inflammation have been reported in these disorders. Furthermore, condensate pH appears to be decreased in both chronic obstructive lung disease and bronchial asthma. This has been referred to as acidopnea and could reflect airway acidification by inflammatory cells. Although safer and more convenient than bronchoalveolar lavage, interpretation of condensate data is complicated by uncertainty regarding the source of condensate solutes and by variable dilution of respiratory droplets from condensed water vapor, which represents more than 99.9% of condensate volumes. This dilution can be estimated from the dilution of plasma constituents such as urea or electrolytes. Because the principal buffer in condensate is NH4, much of which is derived from bacterial degradation of urea in the mouth, condensate pH measurements may not provide accurate estimates of airway pH. Nevertheless, acidification of condensate may be indicative of gastroesophageal reflux, which frequently occurs in obstructive lung diseases and may contribute to cough and bronchospasm. SUMMARY: It is too early to tell how useful condensate studies will be to pulmonary investigators and clinicians. Realization of the enormous potential of this approach will require a thorough understanding of the manner in which these solutions are generated and how they should be analyzed.

Acidosis, Respiratory↗