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BACKGROUND: Mechanical insufflation-exsufflation (MI-E) uses positive and negative pressures to assist weak cough and help clear airway secretions. Laryngeal visualization during MI-E has revealed that inappropriate upper airway responses can impede its efficacy. However, the dynamics of pressure transmission in the upper airways during MI-E is unclear, as are the relationships between anatomical structure, pressure and airflow. RESEARCH QUESTION: Can airflow resistance through the upper airway and the larynx feasibly be calculated during MI-E, and if so, how are the pressures transmitted to the trachea? STUDY DESIGN AND METHODS: Cross-sectional study of ten healthy adults, where MI-E was provided with and without active cough, employing pressure settings +20/-40 and ±40 cmH2O. Airflow and pressure at the level of the facemask were measured using a pneumotachograph, while pressure transducers (positioned via transnasal fiberoptic laryngoscopy) recorded pressures above the larynx and within the trachea. Upper airway resistance (Ruaw) and translaryngeal resistance (Rtl) were calculated (cmH2O/L/sec) and compared to direct observations via laryngoscopy. RESULTS: Positive pressures reached the trachea effectively, while negative tracheal pressures during exsufflation were approximately half of the intended settings. Insufflation pressure increased slightly when passing through the larynx. Participant effort influenced tracheal pressures and the resistances, with findings consistent with laryngoscopic observations. During MI-E, resistance appears dynamic, with Ruaw exceeding Rtl. Inappropriate laryngeal closure increased Rtl during both positive and negative pressures. INTERPRETATION: Upper airway and translaryngeal resistance can feasibly be calculated during MI-E. The findings indicate different transmission dynamics for positive and negative pressures, and that resistances are influenced by participant effort. The findings support using lower insufflation pressures and higher negative pressures in clinical practice.
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Obstrucción de las Vías Aéreas , Enfermedades de la Laringe , Laringe , Disfunción de los Pliegues Vocales , Humanos , Disfunción de los Pliegues Vocales/diagnóstico , Toma de Decisiones , Laringoscopía , Obstrucción de las Vías Aéreas/diagnóstico , Diagnóstico Diferencial , Pliegues Vocales , Disnea/diagnósticoRESUMEN
Objective: Exercise-induced laryngeal obstruction is an important cause of exertional dyspnoea. The diagnosis rests on visual judgement of relative changes of the laryngeal inlet during continuous laryngoscopy exercise (CLE) tests, but we lack objective measures that reflect functional consequences. We aimed to investigate repeatability and normal values of translaryngeal airway resistance measured at maximal intensity exercise. Methods: 31 healthy nonsmokers without exercise-related breathing problems were recruited. Participants performed two CLE tests with verified positioning of two pressure sensors, one at the tip of the epiglottis (supraglottic) and one by the fifth tracheal ring (subglottic). Airway pressure and flow data were continuously collected breath-by-breath and used to calculate translaryngeal resistance at peak exercise. Laryngeal obstruction was assessed according to a standardised CLE score system. Results: Data from 26 participants (16 females) with two successful tests and equal CLE scores on both test sessions were included in the translaryngeal resistance repeatability analyses. The coefficient of repeatability (CR) was 0.62â cmH2O·L-1·s-1, corresponding to a CR% of 21%. Mean±sd translaryngeal airway resistance (cmH2O·L-1·s-1) in participants with no laryngeal obstruction (n=15) was 2.88±0.50 in females and 2.18±0.50 in males. Higher CLE scores correlated with higher translaryngeal resistance in females (r=0.81, p<0.001). Conclusions: This study establishes translaryngeal airway resistance obtained during exercise as a reliable parameter in respiratory medicine, opening the door for more informed treatment decisions and future research on the role of the larynx in health and disease.
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BACKGROUND: Exercise-induced laryngeal obstruction (EILO) is a common cause of exertional breathing problems in young individuals, caused by paradoxical inspiratory adduction of laryngeal structures, and diagnosed by continuous visualization of the larynx during high-intensity exercise. Empirical data suggest that EILO consists of different subtypes, possibly requiring different therapeutic approaches. Currently applied treatments do not rest on randomized controlled trials, and international guidelines based on good evidence can therefore not be established. This study aims to provide evidence-based information on treatment schemes commonly applied in patients with EILO. METHODS AND ANALYSIS: Consenting patients consecutively diagnosed with EILO at Haukeland University Hospital will be randomized into four non-invasive treatment arms, based on promising reports from non-randomized studies: (A) standardized information and breathing advice only (IBA), (B) IBA plus inspiratory muscle training, (C) IBA plus speech therapy, and (D) IBA plus inspiratory muscle training and speech therapy. Differential effects in predefined EILO subtypes will be addressed. Patients failing the non-invasive approach and otherwise qualifying for surgical treatment by current department policy will be considered for randomization into (E) standard or (F) minimally invasive laser supraglottoplasty or (G) no surgery. Power calculations are based on the main outcomes, laryngeal adduction during peak exercise, rated by a validated scoring system before and after the interventions. ETHICS AND DISSEMINATION: The study will assess approaches to EILO treatments that despite widespread use, are insufficiently tested in structured, verifiable, randomized, controlled studies, and is therefore considered ethically sound. The study will provide knowledge listed as a priority in a recent statement issued by the European Respiratory Society, requested by clinicians and researchers engaged in this area, and relevant to 5-7% of young people. Dissemination will occur in peer-reviewed journals, at relevant media platforms and conferences, and by engaging with patient organizations and the healthcare bureaucracy.
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BACKGROUND: The laryngeal tie-forward (LTF) procedure is commonly used to treat intermittent dorsal displacement of the soft palate (iDDSP). There is a wide range in reported efficacy of treating horses with and without a definitive diagnosis of iDDSP. OBJECTIVES: To evaluate the racing performance of harness racehorses in which iDDSP had been definitely diagnosed and treated solely with the LTF procedure. STUDY DESIGN: Retrospective case series. METHODS: Ninety-five harness racehorses were treated with LTF for confirmed iDDSP. A definite diagnosis of iDDSP was made with high-speed treadmill or overground endoscopy. Upper respiratory tract (URT) disorders, short-term complications, and horses returning for recurrence of URT problems were recorded. Performance before and after LTF was assessed by reviewing career race records and comparing performance index (PI), and racing speed marks from the baseline, preoperative, and postoperative periods. The effect of basihyoid-cricoid (BC) net distance shortened on racing performance was assessed. RESULTS: Postoperatively, PI increased in 36/54 (67%, 95% CI 54%-79%) of experienced racehorses, and 44/67 (66%, 54%-77%) established or improved their racing speed mark relative to the preoperative period. As a group, PI decreased by a mean (SE) of 0.9 (0.17) points (P < .001) prior to diagnosis/surgery. Postoperatively, PI increased by 0.5 (0.16) points (P = .003), and racing speed improved by 0.83 (0.22) s (P < .001). Twenty-five percent (17%-34%) and 49% (39%-60%) of horses did not demonstrate a decline in PI and racing speed prior to diagnosis, respectively. Net BC distance shortening did not affect performance postoperatively. Twenty of 95 horses (21%, 13%-29%) had confirmed recurrence of iDDSP 46-708 days postoperatively. MAIN LIMITATIONS: Not all horses were evaluated with exercising endoscopy postoperatively. Racehorses inevitably develop other racing-related problems which confound studies of this nature. CONCLUSIONS: This study provides scientific support for the use of LTF to treat iDDSP in harness racehorses although iDDSP seems to affect harness racehorses differently as individuals.
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AIMS: A cardiopulmonary exercise test (CPET) is the gold standard to evaluate symptom-limiting exercise intolerance, while continuous laryngoscopy performed during exercise (CLE) is required to diagnose exercise-induced laryngeal obstruction. Combining CPET with CLE would save time and resources; however, the CPET data may be distorted by the extra equipment. We therefore aimed to study whether CPET with CLE influences peak oxygen uptake (V'O2 peak) and other gas exchange parameters when compared to a regular CPET. METHODS: Forty healthy athletes without exercise-related breathing problems, 15-35â years of age, performed CPET to peak exercise with and without an added CLE set-up, in randomised order 2-4â days apart, applying an identical computerised treadmill protocol. RESULTS: At peak exercise, the mean difference (95% confidence interval) between CPET with and without extra CLE set-up for V'O2 peak, respiratory exchange ratio (RER), minute ventilation (V'E) and heart rate (HR) was 0.2 (-0.4 to 0.8)â mL·kg-1·min-1, 0.01(-0.007 to 0.027)â units, 2.6 (-1.3 to 6.5)â L·min-1 and 1.4 (-0.8 to 3.5)â beats·min-1, respectively. Agreement (95% limits of agreement) for V'O2 peak, RER and V'E was 0.2 (±3.7)â mL·kg-1·min-1, 0.01 (±0.10)â units and 2.6 (±24.0)â L·min-1, respectively. No systematic or proportional bias was found except for the completed distance, which was 49â m (95% CI 16 to 82â m) longer during CPET. CONCLUSION: Parameters of gas exchange, including V'O2 peak and RER, obtained from a maximal CPET performed with the extra CLE set-up can be used interchangeably with data obtained from standard CPET, thus preventing unnecessary additional testing.
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BACKGROUND: Bits have often been incriminated as a cause of upper respiratory tract obstruction in horses; however, no scientific studies are available to confirm or refute these allegations. Clinical signs of dynamic laryngeal collapse associated with poll flexion (DLC) are induced when susceptible horses are ridden or driven into the bit. OBJECTIVE: To determine whether use of Dr Cook's™ Bitless Bridle, instead of a conventional snaffle bit bridle, would reduce the severity of DLC in affected horses measured objectively using inspiratory tracheal pressures. STUDY DESIGN: Intervention study using each horse as its own control in a block randomised order. METHODS: Nine Norwegian Swedish Coldblooded trotters previously diagnosed with DLC were exercised on two consecutive days using a standardised high-speed treadmill protocol with either a conventional bridle with a snaffle bit, or Dr Cook's™ Bitless Bridle. Head and neck position, rein tension, inspiratory tracheal pressure measurements, and laryngeal videoendoscopy recordings were obtained. A heart rate greater than 200 bpm, and similar degrees of poll flexion/head height, had to be achieved in both bridles for the individual horse's data to be included for comparison. RESULTS: Seven horses' data met the inclusion criteria. The change in mean inspiratory tracheal pressure between free and flexion phases in the bitless bridle (-15.2 ± 12.3 cmH2 O) was significantly greater (P < .001) than in the snaffle bit bridle (-9.8 ± 7.9 cmH2 O). Mean inspiratory pressure during the free phase was significantly (P < .001) more negative with the snaffle bit bridle (-32.3 ± 6.3 cmH2 O), vs the bitless bridle (-28.5 ± 6.9 cmH2 O). Mean pressures in flexion phase, snaffle bridle (-42.1 ± 10.8 cmH2 O), vs bitless bridle (-43.7 ± 15.6 cmH2 O) where not significantly different between bridles (P = .2). MAIN LIMITATION: Small sample size due to difficulty recruiting suitable clinical cases. CONCLUSIONS: This study could not provide any clear evidence that the effect of a snaffle bit in a horse's mouth influences the development or severity of DLC. Instead, head and neck angles induced by rein tension seem to be the key event in provoking DLC in susceptible horses.
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Obstrucción de las Vías Aéreas , Enfermedades de los Caballos , Laringe , Obstrucción de las Vías Aéreas/veterinaria , Animales , Enfermedades de los Caballos/prevención & control , Caballos , Noruega , SueciaRESUMEN
Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac disease and lack of fitness are the major differentials in both species. Laryngoscopic examination during exercise should be performed from rest to peak exertion to allow for a comprehensive diagnosis, including where the airway collapse begins, and thereafter how it progresses. Dynamic disorders with most visual similarity between humans and equines are: aryepiglottic fold collapse (both species); equine dynamic laryngeal collapse (DLC) relative to some forms of human combined supraglottic/glottic collapse; and epiglottic retroversion (both species). Quantitative grading techniques, such as airway pressure measurement, that have proven effective in veterinary research are currently being piloted in human studies. Conditions that appear visually similar are treated in comparable ways. The similarities of anatomy and certain types of dynamic collapse would suggest that the equine larynx provides a good model for human upper respiratory tract obstruction during exercise. Thus, close collaboration between veterinarians and medical personal may lead to further advancements in understanding pathophysiologic processes, and enhance the development of improved diagnostic tests and treatments that will benefit both species.
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OBJECTIVES/HYPOTHESIS: To determine if simultaneous tracheal and supraglottic pressure measurement performed during a continuous laryngoscopy exercise (CLE) test is possible, tolerable, and feasible, and if so, whether measurements can be used to determined airflow resistance over the larynx, thus providing an objective outcome measure for the CLE test, the gold standard for diagnosing exercise-induced laryngeal obstruction. STUDY DESIGN: Explorative descriptive clinical study. METHODS: A CLE test was performed with the addition of two pressure sensors (Mikro-Cath 825-0101; Millar, Houston, TX) placed at the epiglottic tip and at the fifth tracheal ring. To place sensors, laryngeal anesthesia and a channel scope were required. Tolerability and feasibility was determined by a Likert score and subjective indication from subjects and operators. Adjustments to the technique were made to increase tolerability. The pressure data were continuously collected and analyzed for artifacts, drifts, frequency response, and used with flow data to calculate translaryngeal resistance. RESULTS: All subjects (n = 7) completed all procedures. Two main areas of concern were identified regarding tolerability: application of topical anesthesia to the larynx and nasal discomfort due to the added diameter of the laryngoscope. Protocol adjustments improved both. Pressure data were obtained from all procedures in all subjects, were consistent, and followed physiological trends. CONCLUSIONS: Continuous measurement of the translaryngeal pressure gradient during a CLE test is possible, feasible, and tolerable. A CLE test with direct measurement of the translaryngeal pressure gradient might become a valuable tool in the objective assessment of respiratory function, and normal values should be established in health and disease. LEVEL OF EVIDENCE: NA Laryngoscope, 129:2748-2753, 2019.