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1.
OBJECTIVE: To determine the effect of a commercially available nasal strip on airway mechanics in exercising horses. ANIMALS: 6 horses (5 Standardbreds and 1 Thoroughbred). PROCEDURE: Horses exercised on a treadmill at speeds corresponding to 100 and 120% of maximal heart rate with and without application of a commercially available nasal strip. Concurrently, tracheal pressures, airflow, and heart rate were measured. Peak inspiratory and expiratory tracheal pressures, airflow, respiratory frequency, and tidal volume were recorded. Inspiratory and expiratory airway resistances were calculated by dividing peak pressures by peak flows. Endoscopic examination of the narrowest point of the nasal cavity (ie, nasal valve) was performed in 1 resting horse before, during, and after application of a nasal strip. RESULTS: During exercise on a treadmill, peak tracheal inspiratory pressure and inspiratory airway resistance were significantly less when nasal strips were applied to horses exercising at speeds corresponding to 100 and 120% of maximal heart rate. Application of the nasal strip pulled the dorsal conchal fold laterally, expanding the dorsal meatus. CONCLUSIONS AND CLINICAL RELEVANCE: The commercially available nasal strip tented the skin over the nasal valve and dilated that section of the nasal passage, resulting in decreased airway resistance during inspiration. The nasal strip probably decreases the amount of work required for respiratory muscles in horses during intense exercise and may reduce the energy required for breathing in these horses.  相似文献   

2.
OBJECTIVE: To determine the effect of a tongue-tie on upper airway mechanics in clinically normal horses exercising on a treadmill following sternothyrohyoid myectomy. ANIMALS: 6 Standardbreds. PROCEDURE: Upper airway mechanics were measured with horses exercising on a treadmill at 5, 8, and 10 m/s 4 weeks after a sternothyrohyoid myectomy was performed. Pharyngeal and tracheal inspiratory and expiratory pressures were measured by use of transnasal pharyngeal and tracheal catheters connected to differential pressure transducers. Horses were fitted with a facemask and airflow was measured by use of a pneumotachograph. Horses underwent a standardized exercise protocol on a treadmill at 5, 8, and 10 m/s with and without a tongue-tie in a randomized cross-over design. Inspiratory and expiratory airflow, tracheal pressure, and pharyngeal pressure were measured, and inspiratory and expiratory resistances were calculated. RESULTS: We were unable to detect an effect of a tongue-tie on any of the respiratory variables measured. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that a tongue-tie does not alter upper airway mechanics following sternothyrohyoid myectomy in clinically normal horses during exercise.  相似文献   

3.
REASONS FOR PERFORMING STUDY: Nasopharyngeal collapse has been observed in horses as a potential cause of exercise intolerance and upper respiratory noise. No treatment is currently available and affected horses are often retired from performance. OBJECTIVE: To determine the effect of bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction on nasopharyngeal function and airway pressures in exercising horses. METHODS: Endoscopic examinations were performed on horses at rest and while running on a treadmill at speeds corresponding to HRmax50, HRmax75 and HRmax, with upper airway pressures measured with and without bilateral glossopharyngeal nerve block. RESULTS: Bilateral glossopharyngeal nerve block caused stylopharyngeus muscle dysfunction and dorsal nasopharyngeal collapse in all horses. Peak inspiratory upper airway pressure was significantly (P = 0.0069) more negative at all speeds and respiratory frequency was lower (P = 0.017) in horses with bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction compared to control values. CONCLUSIONS: Bilateral glossopharyngeal nerve anaesthesia produced stylopharyngeus muscle dysfunction, dorsal pharyngeal collapse and airway obstruction in all horses. POTENTIAL RELEVANCE: The stylopharyngeus muscle is probably an important nasopharyngeal dilating muscle in horses and dysfunction of this muscle may be implicated in clinical cases of dorsal nasopharyngeal collapse. Before this information can be clinically useful, further research on the possible aetiology of stylopharyngeus dysfunction and dysfunction of other muscles that dilate the dorsal and lateral walls of the nasopharynx in horses is needed.  相似文献   

4.
Reasons for performing the study: Dynamic laryngeal collapse (DLC) associated with poll flexion is a performance limiting dynamic upper airway disorder commonly diagnosed in Coldblooded trotters. An inspiratory obstruction occurs when affected horses are driven with tension on the reins, inducing poll flexion. To date, surgical treatment and conservative management have failed to improve racing performance in affected horses. Objectives: To test the efficacy of an external device, the modified checkrein, in limiting poll flexion, diminishing laryngeal collapse and improving airway mechanics when horses are driven on a treadmill with tension on the reins and test the hypothesis that the modified checkrein will limit poll flexion thereby improving endoscopic appearance of the larynx and reduce airway obstruction in harness racehorses affected with DLC. Methods: Fourteen Norwegian Coldblooded trotter (NCT) racehorses previously diagnosed with DLC associated with poll flexion exercised on a high‐speed treadmill at speeds that resulted in heart rate >200 beats/min. Upper airway videoendoscopy recordings, tracheal pressures and video recordings of the head and neck position were collected while horses exercised with the conventional checkrein on Day 1 and the modified checkrein on Day 2. Results: The modified checkrein successfully limited poll flexion as measured by no change in head position parameters between phases of no rein tension and phases of rein tension. Endoscopic scores were significantly improved (arytenoids cartilage collapse P<0.0001; vocal fold collapse P<0.0001) and tracheal peak inspiratory pressures were significantly less negative (P = 0.0162) when horses were fitted with the modified checkrein compared to the conventional checkrein. Conclusions and potential relevance: The modified checkrein successfully limited poll flexion and also prevented upper airway obstruction in NCT horses affected with DLC associated with poll flexion. The modified checkrein seems promising in offering a method of conservative management in harness racehorses affected with this disorder.  相似文献   

5.
REASONS FOR PERFORMING STUDY: It has long been recognised that the production of abnormal respiratory sounds by horses during exercise is frequently associated with upper airway obstructions. Respiratory acoustic measurements have shown promise in investigation of upper airway disorders in man and, more recently, in horses with experimentally-induced obstructions. OBJECTIVES: To evaluate sounds from exercising horses with naturally occurring dynamic obstructions of the upper respiratory tract and to compare these with those from normal horses in order to determine whether different obstructions produce characteristic spectral patterns. METHODS: The audio signal, airflow and videoendoscopic images were recorded simultaneously during an incremental exercise test on a high-speed treadmill. RESULTS: Spectral analysis of the audio signal showed marked differences between control and clinically afflicted horses. Dorsal displacement of the soft palate was characterised by a narrow low frequency (20-80 Hz) peak during expiration. Horses with dynamic laryngeal collapse produced inspiratory sounds characterised by a broad band high frequency spectral component in the range 1.1-2.7 kHz. CONCLUSIONS AND POTENTIAL RELEVANCE: Spectral analysis of respiratory sounds in horses has potential as a diagnostic technique for field use especially when facilities for high-speed treadmill assessment are not practicable.  相似文献   

6.
OBJECTIVE: To determine the effect of a tongue-tie on upper airway mechanics in exercising horses. ANIMALS: 5 Standardbreds. PROCEDURE: Peak inspiratory and expiratory tracheal and pharyngeal pressures and airflow were measured while horses exercised on a treadmill with and without a tongue-tie. Respiratory rate was also measured. Horses ran at speeds that corresponded to 50 (HR50), 75, 90 (HR90), and 100% of maximal heart rate. The tongue-tie was applied by pulling the tongue forward out of the mouth as far as possible and tying it at the level of the base of the frenulum to the mandible with an elastic gauze bandage. Peak inspiratory and expiratory tracheal, pharyngeal, and translaryngeal resistance, minute ventilation, and tidal volume were calculated. Data were analyzed by use of 2-way repeated-measures ANOVA. For post hoc comparison of significant data, the Student-Newman-Keuls test was used. RESULTS: We were unable to detect significant differences between groups for peak inspiratory or expiratory tracheal or pharyngeal resistance, peak pressure, peak expiratory flow, tidal volume, respiratory rate, or minute ventilation. Horses that ran with a tongue-tie had significantly higher peak inspiratory flows, compared with horses that ran without a tongue-tie. In the post hoc comparison, this effect was significant at 4 m/s, HR50, and HR90. CONCLUSION AND CLINICAL RELEVANCE: Application of a tongue-tie did not alter upper respiratory mechanics in exercising horses and may be beneficial in exercising horses with certain types of obstructive dysfunction of the upper airways. However, application of a tongue-tie does not improve upper airway mechanics in clinically normal horses.  相似文献   

7.
Reasons for performing study: Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses. Objective: To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy. Methods: Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined. Results: Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations. Conclusions: Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy. Potential relevance: This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function.  相似文献   

8.
Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38 degrees incline). Inspiratory and expiratory airflows (VImax, VEmax, respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE, respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3- values. Heart rate (HR) was determined with an HR monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (LRLN; base line), 14 days after LRLN, 30 days after ventriculectomy (44 days after LRLN), and 14 days after prosthetic laryngoplasty (58 days after LRLN). Before LRLN (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased HR, respiratory frequency, VImax, VEmax, PuI, PuE, Hb, and PaCO2 values and decreased PaO2, pH, and HCO3- values; inspiratory and expiratory impedances were unchanged. After LRLN, inspiratory impedance and PuI were significantly (P less than 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The VImax and respiratory frequency were significantly (P less than 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE, VEmax, HR, PaO2, pH, Hb, or expiratory impedance values.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
The efficacy of a nerve muscle pedicle (NMP) graft in restoring upper airway function was evaluated in exercising horses with induced left laryngeal hemiplegia. The NMP graft was created from the first cervical nerve and the omohyoideus muscle and transplanted into the left cricoarytenoideus dorsalis muscle. Seven adult Standardbreds were trained to exercise on a treadmill inclined at 6.38 degrees. With the horses at rest and exercising at 4.2 and 7.0 m/s, the following variables were recorded: peak inspiratory and expiratory transupper airway pressures (defined as the pressure difference between a lateral tracheal catheter and a mask catheter), peak inspiratory and expiratory air flow, inspiratory and expiratory impedance, tidal volume, minute ventilation, heart rate, and respiratory frequency. Measurements were made before left recurrent laryngeal neurectomy (LRLN), 28 days after LRLN, and 12, 24, and 52 weeks after the NMP graft (n = 5) or sham operation (n = 2). Before LRLN, exercise increased inspiratory and expiratory air flow and transupper airway pressure, whereas the impedance was unchanged. After LRLN, transupper airway inspiratory pressure and impedance were significantly greater and inspiratory air flow was significantly less than baseline values at 7.0 m/s. The sham operation did not improve airway function. Twelve weeks after insertion of the NMP graft, inspiratory impedance and inspiratory air flow were significantly different (improved) from LRLN values. Twenty-four weeks after insertion of the NMP graft, inspiratory impedance was not significantly different from LRLN values.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
OBJECTIVES: To determine (1) if the cricothyroid muscle had respiratory-related electromyographic (EMG) activity that increased with respiratory effort and (2) if bilateral cricothyroid myotomy resulted in vocal fold instability and collapse in exercising horses. STUDY DESIGN: Experimental. ANIMALS: Seven (3 EMG; 4 cricothyroid myotomy) Standardbred horses. METHODS: Three horses exercised on a treadmill at speeds corresponding to the speed that produced maximum heart rate (HR(max)), 75% of maximum heart rate (HR(75%max)), and 50% of maximum heart rate (HR(50%max)) for 60 seconds at each speed while EMG activity of the cricothyroid muscle and nasopharyngeal pressures were measured. Another 4 normal horses were exercised on the treadmill at HR(max) and HR(75%max) for 60 seconds at each speed before and after bilateral cricothyroid myotomy. Upper airway pressures were measured and videoendoscopic examinations were performed and videotaped at each speed. RESULTS: Peak phasic EMBG activity of the cricothyroid muscle was coincident with inspiration and increased with treadmill speed. Bilateral cricothyroid myotomy resulted in vocal fold collapse in all horses. Mean peak inspiratory pressures were significantly more negative compared with control values at both HR(max) and HR(75%max). CONCLUSIONS: Cricothyroid muscle dysfunction may be implicated in vocal fold collapse and likely causes inspiratory airway obstruction in exercising horses. CLINICAL RELEVANCE: Conditions compromising cricothyroid muscle function or motor innervation could result in vocal fold collapse.  相似文献   

11.
OBJECTIVE: To report the effect of unilateral laser vocal cordectomy on respiratory noise and airway function in horses with experimentally induced laryngeal hemiplegia (LH). STUDY DESIGN: Experimental study. ANIMALS: Six Standardbred horses without upper airway abnormalities at rest or during high-speed treadmill exercise. METHODS: Respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)) were measured before (baseline) and 14 days after induction of LH by left recurrent laryngeal neurectomy, and again 30, 60, 90, and 120 days after endoscopically assisted laser cordectomy of the left vocal cord. Data were collected with the horses exercising on a treadmill at a speed producing maximum heart rate (HR(max)). RESULTS: In horses exercising at HR(max), induction of LH caused a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)). The sound intensity of formant 1 (F(1)) was unaffected by induction of LH. Laser vocal cordectomy had no effect on SL, or on the sound intensity of F(1) and F(3). At 30, 60, 90, and 120 days after surgery, P(Ui) and the sound intensity of F(2) were significantly reduced, but these variables remained significantly different from baseline values. CONCLUSIONS: Unilateral laser vocal cordectomy did not effectively improve upper airway noise in horses with LH. The procedure decreased upper airway obstruction to the same degree as bilateral ventriculocordectomy. CLINICAL RELEVANCE: Currently, laser vocal cordectomy cannot be recommended for the treatment of upper airway noise in horses with LH.  相似文献   

12.
The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at least 14 days after prosthetic larynogoplasty. Increasing treadmill speed from period A to period D progressively increased heart rate, respiratory frequency, peak inspiratory flow, and peak expiratory flow, but inspiratory resistance and expiratory resistance remained unchanged. Neither left recurrent laryngeal neutrectomy nor prosthetic laryngoplasty affected heart rate, respiratory frequency, peak expiratory flow, or expiratory resistance when compared with those values at the control measurement periods. Left recurrent laryngeal neurectomy resulted in inspiratory flow limitation at peak inspiratory flow of approximately 25 L/s, and increased inspiratory resistance at periods D and E. Subsequent prosthetic laryngoplasty alleviated the flow limitation and reduced inspiratory resistance at measurement periods D and E.  相似文献   

13.
Reason for performing study: Dynamic laryngeal collapse (DLC) associated with poll flexion is a newly diagnosed upper respiratory tract obstructive disorder that causes poor racing performance. Objectives: To determine if Norwegian Coldblooded Trotters (NCTs) affected with DLC associated with poll flexion differ from normal, elite NCTs based on simple airway mechanics measurements. Methods: Five normal elite NCTs and 6 NCTs diagnosed previously with DLC underwent treadmill videoendoscopy while tracheal pressures were measured continuously. Alternating head positions were used such that horses were exercised with free head carriage and induced poll flexion at heart rates >200 beats/min. Results: Peak inspiratory tracheal pressures were significantly more negative for horses with DLC compared to the elite horses. This difference was only significant during the exercise phases when the poll region was flexed, P = 0.0015. Head position significantly affected peak inspiratory pressure for both elite and affected horses, P<0.0001. Conclusions and clinical relevance: Induced poll flexion significantly affected peak inspiratory pressure (PIP) in all horses; however, PIPs were significantly more negative in those affected with DLC. Based upon the tracheal pressure measurements recorded in this study, DLC in NCTs is a severe obstructive upper respiratory tract disorder that is induced by poll flexion.  相似文献   

14.
REASONS FOR PERFORMING STUDY AND OBJECTIVE: To review the prevalence of single and complex forms of dynamic airway obstructions within a large group of Thoroughbred horses in training referred for investigation of poor performance. METHODS: Video-endoscopic recordings of the upper respiratory tract made during a standardised treadmill exercise test of 600 Thoroughbred racehorses were reviewed and analysed in real time and slow motion to identify dynamic collapse by the tissues bordering onto the pharyngeal and laryngeal airways. RESULTS: Dynamic collapse within the nasopharynx or larynx was confirmed in 471 of the 600 horses. Dorsal displacement of the soft palate (DDSP; 50%) and palatal instability (33%) were the disorders most frequently identified. It was concluded that deglutition is not a significant event in the triggering of DDSP. Complex forms of dynamic collapse were present in 30% of the horses with upper respiratory tract obstructions. A significant influence of age on the prevalence of DDSP and dynamic laryngeal collapse was identified. There was an increased risk of DDSP in younger horses, and of laryngeal collapse in older horses. No association with gender or format of racing was identified. CONCLUSIONS AND POTENTIAL RELEVANCE: Palatal instability and DDSP comprised the most frequently encountered forms of dynamic collapse within the upper respiratory tract of the Thoroughbred racehorses in this study and are probably expressions of the same nasopharyngeal malfunction. Complex obstructions, i.e. where more than one structure collapses into the airway, occur frequently and therefore treatments that address solitary disorders may often be unsuccessful. Younger horses were found to be at greater risk of sustaining DDSP while older horses seemed more at risk to vocal cord collapse but not to collapse of the arytenoid cartilage itself.  相似文献   

15.
OBJECTIVE: To report dynamic collapse of the apex of the left corniculate process under the right corniculate process into the airway at the dorsal apposition of the paired arytenoid cartilages during exercise as a cause of upper airway dysfunction in horses. DESIGN: Retrospective study. ANIMALS: Fifteen horses with a history of poor performance and/or upper respiratory tract noise during exercise. METHODS: Video recordings of all horses referred for upper airway evaluation using high-speed treadmill videoendoscopy (HSTV) between January 1998 and December 2003 were reviewed. Records of horses that developed dynamic collapse of the apex of the left corniculate process into the airway were included. Clinical history, age, gender, breed, and use of the horse were retrieved. RESULTS: Of 309 horses referred for examination for poor performance and/or upper respiratory tract noise during exercise, 15 (4.9%) had collapse of the apex of the left corniculate process under the right and into the airway at the dorsal apposition between the paired arytenoid cartilages during HSTV. There were 3 females and 13 males, aged from 2 to 5 years. Five horses had previous surgery for left recurrent laryngeal neuropathy (RLN): 2 had nerve muscle pedicle graft and 3 had laryngeal prosthesis. During HSTV, all 15 horses had progressive collapse of the apex of the left corniculate process under the right at the dorsal apposition of the 2 arytenoid cartilages, and into the dorsal aspect of the rima glottidis. Review of video recordings revealed that collapse of the apex of the corniculate process was followed by progressive collapse of the left aryepiglottic fold and left vocal fold. The ventral aspect of the left corniculate cartilage maintained abduction in all horses. Two horses also had progressive collapse of the right vocal fold, 1 had rostral displacement of the palatopharyngeal arch, and another had dorsal displacement of the soft palate. CONCLUSIONS: Dynamic collapse of the apex of the left corniculate process of the arytenoid cartilage under the right is an uncommon cause of upper airway dysfunction in horses and the pathogenesis is unclear. We speculate that the left arytenoideus transversus muscle is unable to support the dorsal apposition between the arytenoid cartilages. This loss of support allows the elastic cartilage of the left corniculate process to collapse under the right and into the airway, as inspiratory pressure increases during exercise. This condition may be associated with an unusually advanced neuropathy of the adductor components of the left recurrent laryngeal nerve and may be an unusual manifestation of RLN; however, this is speculative and further investigation is required to determine its cause. CLINICAL RELEVANCE: Dynamic collapse of the apex of the left corniculate process and into the airway at the dorsal apposition between the paired arytenoid cartilages can only be diagnosed during HSTV. It is an uncommon cause of upper airway dysfunction but may affect the athletic potential of racing Thoroughbreds and Standardbreds.  相似文献   

16.
REASONS FOR PERFORMING STUDY: Recent studies have evaluated surgical techniques aimed at reducing noise and improving airway function in horses with recurrent laryngeal neuropathy (RLN). These techniques require general anaesthesia and are invasive. A minimally invasive transnasal surgical technique for treatment of RLN that may be employed in the standing, sedated horse would be advantageous. OBJECTIVE: To determine whether unilateral laser-assisted ventriculocordectomy (LVC) improves upper airway function and reduces noise during inhalation in exercising horses with laryngeal hemiplegia (LH). METHODS: Six Standardbred horses were used; respiratory sound and inspiratory transupper airway pressure (Pui) measured before and after induction of LH, and 60, 90 and 120 days after LVC. Inspiratory sound level (SL) and the sound intensities of formants 1, 2 and 3 (Fl, F2 and F3, respectively), were measured using computer-based sound analysis programmes. In addition, upper airway endoscopy was performed at each time interval, at rest and during treadmill exercise. RESULTS: In LH-affected horses, Pui, SL and the sound intensity of F2 and F3 were increased significantly from baseline values. At 60 days after LVC, Pui and SL had returned to baseline, and F2 and F3 values had improved partially compared to LH values. At 90 and 120 days, however, SL increased again to LH levels. CONCLUSIONS: LVC decreases LH-associated airway obstruction by 60 days after surgery, and reduces inspiratory noise but not as effectively as bilateral ventriculocordectomy. POTENTIAL RELEVANCE: LVC may be recommended as a treatment of LH, where reduction of upper airway obstruction and respiratory noise is desired and the owner wishes to avoid risks associated with a laryngotomy incision or general anaesthesia.  相似文献   

17.
An extralaryngeal approach to partial arytenoidectomy in the horse was developed by in vitro experiments on isolated larynges and then on intact equine cadavers. The goals of the approach were to preserve the laryngeal mucosa, eliminate the need for a laryngotomy or tracheotomy, and minimize postoperative complications. The new approach was evaluated in seven horses with normal upper respiratory tracts. Left laryngeal hemiplegia was surgically created, and, after a 30-day convalescence, left partial arytenoidectomy was performed using an extralaryngeal approach. The left-to-right hemilaryngeal ratio was calculated before and after left recurrent laryngeal neurectomy and 60 days after partial arytenoidectomy. Left partial arytenoidectomy was successfully completed in all horses without performing a laryngotomy or tracheotomy. Preservation of the laryngeal mucosa (6/7 horses) and apparent stabilization of the adjacent soft tissue (6/7 horses) was achieved. In one horse, a 1 -cm laryngeal mucosal tear healed without complication, and in another some collapse of adjacent soft tissue occurred when a retention suture failed. The mean left-to-right hemilaryngeal ratio was significantly increased compared to horses with left laryngeal hemiplegia, but it remained significantly less than the pre-recurrent laryngeal neurectomy ratio (p < .05). Coughing, aspiration, and airway narrowing were not observed. Partial arytenoidectomy could be reliably performed through an extralaryngeal approach in horses with a normal underlying arytenoid cartilage with preservation of the laryngeal mucosa.  相似文献   

18.
OBJECTIVE: To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA). STUDY DESIGN: Repeated measures under the following conditions: Control, RLN, LPVC, and MPA. ANIMALS: Six horses. METHODS: Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HR(max)). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial 2, upper airway pressure and airflow were determined. Tracheobronchial aspirates were performed after exercise to quantify airway contamination. RESULTS: Compared with control, RLN significantly increased inspiratory impedance and worsened exercise-induced hypoxemia. At 80% HR(max), LPVC restored most variables to control values. At 100% HR(max), LPVC improved all variables, but did not restore minute volume, arterial pH, and PaCO(2). At 80% HR(max), MPA restored all variables except bicarbonate to control values. At 100% HR(max), MPA improved all variables, but did not statistically restore minute ventilation or bicarbonate level. Only minor differences were noted between LPVC and MPA. Both resulted in equivalent tracheal contamination. CONCLUSIONS: Airway mechanics and arterial blood gas values were not restored to normal after either LPVC or MPA in horses exercising at HR(max). This does not affect ventilation at sub-maximal exercise, but has clinical implications at HR(max). Both procedures diminish normal laryngeal protective mechanisms. CLINICAL RELEVANCE: At sub-maximal exercise intensities both LPVC and MPA restore airway ventilation to normal. At maximal exercise the superiority of LPVC over MPA is slight.  相似文献   

19.
Reflex responses of the upper airway muscles during experimental nasal and tracheal occlusions were studied in 21 anesthetized dogs breathing through the nose or a tracheostomy (tracheal cannula). Out of them, five animals were examined for maintained negative and positive pressures applied to the isolated upper airway. When the nose was occluded at end-expiration during three consecutive breathings, the electromyographic (EMG) activity of alae nasi (AN) and posterior cricoarytenoid (PCA) muscle markedly increased. The upper airway was subjected to negative pressure, -2.41 approximately -3.04 kPa (n = 34) by these nasal occlusions. The activity of upper airway muscles was also increased by tracheal occlusions. However, such augmentation of PCA activity was much less in tracheal occlusions than nasal occlusions, whereas there was the smaller difference in AN activity between both occlusions. During nasal occlusions, a prolongation of the inspiratory time (TI) was observed. Furthermore, maintained negative pressure applied to the isolated upper airway provoked an augmentation of PCA activity. Such an augmented EMG activity of PCA and the prolongation of TI were largely diminished by sectioning the superior laryngeal nerves. These results proves that the upper airway muscles play an important role to protect the upper airway from collapsing by nasal occlusions. In addition, it is suggested that a lack of lung volume feedback is substantially concerned with the activation of AN, while negative pressure in the upper airway is essential to stimulate PCA.  相似文献   

20.
REASONS FOR PERFORMING STUDY: Laryngoplasty is the technique of choice for treatment of laryngeal hemiplegia, with the aim of improving airway function and/or eliminating respiratory noise. However, there are no quantitative data in the literature describing the effect of laryngoplasty on upper airway noise or its relationship to upper airway mechanics in horses with laryngeal hemiplegia. OBJECTIVES: To determine whether laryngoplasty reduces respiratory noise in exercising horses with laryngeal hemiplegia; and to establish whether the degree of upper airway obstruction can be predicted by upper airway noise, or the degree of arytenoid abduction correlated with airway obstruction and noise production. METHODS: Six Standardbred horses with normal upper airways during maximal exercise were used. Respiratory sounds and inspiratory transupper airway pressure (Pui) were measured in all horses before and after induction of laryngeal hemiplegia and 30, 60 and 90 days after laryngoplasty. Inspiratory sound level (SL) and the sound intensity of the 3 inspiratory formants (F1, F2 and F3, respectively) were measured using a computer-based sound analysis programme. The degree of abduction was graded by endoscopic visualisation 1, 30, 60 and 90 days post operatively. Linear regression analysis was used to determine correlations between Pui, sound indices and grades of arytenoid abduction. RESULTS: In laryngeal hemiplegia-affected horses, Pui, inspiratory SL and the sound intensity of F1, F2 and F3 were significantly increased. At 30 days following laryngoplasty, the sound intensity of F1 and Pui returned to baseline values. The sound intensities of F2, F3 and SL were significantly improved from laryngeal hemiplegia values at 30 days post operatively, but did not return to baseline at any measurement period. Sound level, F2 and F3 were significantly correlated with Pui (P<0.05), but the correlations were weak (r2 = 0.26, 035 and 0.40, respectively). Grade of abduction and F2 were positively and significantly correlated (P<0.006, r2 = 0.76). Grade of arytenoid abduction and Pui were not correlated (P = 0.12). CONCLUSIONS: Laryngoplasty reduced inspiratory noise in laryngeal hemiplegia-affected horses by 30 days following surgery, but did not return it to baseline values. While upper airway noise and Pui were correlated, this relationship was insufficiently strong to predict Pui from noise in individual animals. The degree of arytenoid abduction was not correlated with Pui, but was positively correlated with noise production. POTENTIAL RELEVANCE: Laryngoplasty reduces upper airway noise in horses with laryngeal hemiplegia, but is not as effective as bilateral ventriculocordectomy in this regard, although respiratory noise reduction occurs more rapidly than with bilateral ventriculocordectomy. Residual noise during exercise cannot be used as a predictor of improvement in upper airway function in individual horses following laryngoplasty. The degree of arytenoid abduction obtained following surgery does not affect upper airway flow mechanics. Interestingly, we found that the greater the arytenoid abduction, the louder the respiratory noise.  相似文献   

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