Effects of doxapram HCl on laryngeal function of normal dogs and dogs with naturally occurring laryngeal paralysis

OBJECTIVES: To compare the effects of IV doxapram on glottic size and arytenoid motion in normal dogs and in dogs with laryngeal paralysis. STUDY DESIGN: Prospective experimental and clinical trials. ANIMALS: Six healthy dogs weighing 24.5 +/- 3.9 kg and six dogs weighing 27.4 +/- 11.5 kg suspected of having laryngeal paralysis. METHODS: Dogs were pre-medicated with acepromazine and butorphanol, and a light plane of anesthesia was induced with isoflurane by mask. Videoendoscopic examination of laryngeal function was recorded before (baseline) and after IV doxapram administration. Normalized glottal gap area (NGGA) at maximal inspiration and expiration, and percentage change in height, width, area, and NGGA were calculated with measurements from digitized images of the glottal gap. RESULTS: Active arytenoid motion was present in all normal dogs at baseline. After doxapram administration, depth of respiration appeared greater, but arytenoid motion, as measured by percentage change in NGGA, and in area and width, did not significantly increase in normal dogs. No arytenoid motion was detected in dogs with laryngeal paralysis at baseline; however, rima glottidis NGGA of dogs with laryngeal paralysis was greater at inspiration and expiration than normal dogs. After doxapram administration, dogs with laryngeal paralysis developed paradoxical arytenoid motion and significant, negative percentage change in area (-61%) and NGGA (-145%) because of inward collapse of the arytenoids during inspiration. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of doxapram during laryngeal examination is useful for differentiating normal dogs from dogs with laryngeal paralysis. Dogs with laryngeal paralysis may suffer extreme glottic constriction with vigorous respirations, and may require intubation during examination.     

The effects of doxapram hydrochloride (dopram-V) on laryngeal function in healthy dogs

Laryngeal dysfunction is assessed most accurately by direct visualization of the larynx under a light plane of anesthesia. If the plane of anesthesia used is too deep, laryngeal structures may appear paralyzed and remain in a paramedian position. Doxapram hydrochloride is a known respiratory stimulant. We hypothesized that doxapram would significantly increase intrinsic laryngeal motion in healthy anesthetized dogs. The goal of this study was to evaluate the effect of doxapram on the area of rima glottidis (RG) in healthy dogs. Thirty healthy dogs were studied. Dogs were premedicated with butorphanol tartrate (0.22 mg/kg IV), acepromazine maleate (0.05 mg/kg SC), and glycopyrrolate (0.005 mg/kg SC), followed by induction with propofol (4 mg/kg IV). Intrinsic laryngeal motion observed in each dog was recorded on videotape after induction. Doxapram then was administered (2.2 mg/kg IV) and respirations again were recorded. Representative breaths for each dog were photographed during 4 phases of respiration (inspiration at rest, inspiration with doxapram, expiration at rest, and expiration with doxapram). The area of the RG then was calculated by using a computer-assisted analysis program. Results of each category were compared by using a 1-way analysis of variance; P < or = .05 was considered significant. Doxapram visibly increased respiratory effort, and was associated with increased intrinsic laryngeal motion. Compared to the resting state, the area of the RG was significantly increased after doxapram administration during both inspiration and expiration. We propose the routine use of doxapram during laryngoscopy to increase intrinsic laryngeal motion and aid in the diagnosis of laryngeal dysfunction.     

A multisite case report on the clinical use of sevoflurane in dogs

The purpose of this report was to evaluate the clinical safety and efficacy of sevoflurane as an inhalant anesthetic in dogs. Subjective and objective data from 196 clinical cases utilizing sevoflurane as the maintenance anesthetic was collected at three sites. After preanesthetic evaluation, the attending anesthesiologist assigned the dogs to one of the following six anesthetic protocols: protocol 1, oxymorphone premedication and thiopental induction; protocol 2, oxymorphone/acetylpromazine premedication and thiopental induction; protocol 3, xylazine/butorphanol premedication and thiopental induction; protocol 4, opioid premedication and propofol induction; protocol 5, optional premedication and mask induction with sevoflurane in oxygen; and protocol 6, optional premedication and optional induction. The average quality of induction, maintenance, and recovery was good to excellent in all protocols. The three most common side effects during maintenance and recovery were hypotension, tachypnea, and apnea. Sevoflurane produces anesthesia in dogs comparable to the other inhalation anesthetics currently used (i.e., halothane and isoflurane) for diagnostic or therapeutic procedures.     

Effects of preanesthetic administration of morphine on gastroesophageal reflux and regurgitation during anesthesia in dogs

OBJECTIVE: To determine the effect of morphine administered prior to anesthesia on the incidence of gastroesophageal reflux (GER) in dogs during the subsequent anesthetic episode. ANIMALS: 90 dogs (30 dogs/group). PROCEDURE: The randomized prospective clinical study included healthy dogs with no history of vomiting. Dogs were scheduled to undergo elective orthopedic surgery. Food was withheld for (mean+/-SD) 17.8+/-4.1 hours prior to induction of anesthesia. The anesthetic protocol included acepromazine maleate, thiopental, and isoflurane. Dogs were randomly selected to receive morphine at various dosages (0, 0.22, or 1.10 mg/kg, IM) concurrent with acepromazine administration prior to induction of anesthesia. A sensor-tipped catheter was used to measure esophageal pH, and GER was defined as a decrease in pH to < 4 or an increase to > 7.5. RESULTS: 40 dogs had acidic reflux, and 1 had biliary reflux. Proportions of dogs with GER were 8 of 30 (27%), 15 of 30 (50%), and 18 of 30 (60%) for morphine dosages of 0, 0.22, and 1.10 mg/kg, respectively. Mean duration of GER was 91.4+/-56.8 minutes. There was no significant association between GER and age, weight, vomiting after preanesthetic medication, administration of antimicrobials, or start of surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Most healthy dogs vomit after a large dose of morphine, but vomiting does not increase the likelihood of GER during the subsequent anesthetic episode. Administration of morphine prior to anesthesia substantially increases the incidence of GER during the subsequent anesthetic episode.     

Comparison of the effects of alfaxalone and propofol with acepromazine,butorphanol and/or doxapram on laryngeal motion and quality of examination in dogs

Objective

To compare the effects of alfaxalone and propofol, with and without acepromazine and butorphanol followed by doxapram, on laryngeal motion and quality of laryngeal examination in dogs.

Laryngeal function in normal dogs administered isoflurane following partial clearance of alfaxalone or propofol

ObjectiveTo assess laryngeal function in normal dogs administered isoflurane following partial clearance of alfaxalone or propofol.Study designRandomized experimental crossover study.AnimalsA group of 12 purpose-bred, male Beagle dogs.MethodsDogs were randomly assigned to one of two treatments: alfaxalone–isoflurane (ALF-ISO) or propofol–isoflurane (PRO-ISO) and anesthetized for three video laryngoscopy examinations. The alternate treatment occurred after ≥ 14 days interval. Examinations were performed after induction of anesthesia (LS-A), after 20 minutes of breathing isoflurane via a facemask (LS-B) and after a further 20 minutes of isoflurane (LS-C). Parameters of objective laryngeal function included inspiratory rima glottidis surface area (RGSA-I), expiratory rima glottidis surface area (RGSA-E) and % RGSA increase, calculated from three consecutive respiratory cycles in the final 15 seconds of each video laryngoscopy examination. The % RGSA increase was calculated using [(RGSA-I – RGSA-E)/RGSA-E] × 100. Subjective laryngeal function was evaluated independently by two experienced surgeons blinded to treatment.ResultsThe % RGSA increase within each treatment was greater for LS-B and LS-C than for LS-A (ALF-ISO: p = 0.03, PRO-ISO: p = < 0.001). There was no difference within each treatment from LS-B compared with LS-C. RGSA-I increased within each treatment from LS-A to both LS-B and LS-C (ALF-ISO: p = 0.002) and to LS-C (PRO-ISO: p = 0.006). Subjective laryngeal function scores improved from LS-A to LS-C.Conclusions and clinical relevanceLaryngeal function improved from postinduction examination following either 20 or 40 minutes of anesthesia with isoflurane via facemask. This study demonstrates that isoflurane may have a lesser effect on arytenoid abduction activity compared with more commonly used intravenous induction anesthetics (alfaxalone and propofol).     

Effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy

OBJECTIVE: To determine the effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy. DESIGN: Randomized, controlled clinical trial. ANIMALS: 22 clinically normal client-owned dogs. PROCEDURE: 60 minutes before induction of anesthesia, 11 dogs were given ketoprofen (2 mg/kg [0.9 mg/lb], i.m.), and the other 11 were given saline (0.9% NaCl) solution. Dogs were premedicated with glycopyrrolate, acepromazine, and butorphanol and anesthetized with thiopental; anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by an experienced surgeon, and butorphanol was given 15 minutes before completion of the procedure. Objective behavioral scores and numerical pain scores at rest and with movement were recorded every 2 hours for 12 hours after surgery and then every 4 hours for an additional 12 hours. RESULTS: Preoperative administration of ketoprofen did not reduce the dose of thiopental required to induce anesthesia or the end-tidal concentration of isoflurane required to maintain anesthesia. Activity levels and median objective behavioral scores were significantly higher 4 and 6 hours after surgery in dogs given ketoprofen than in dogs given saline solution. However, mean numerical pain scores in dogs given ketoprofen were not significantly different from scores for dogs given saline solution at any time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that preoperative administration of ketoprofen does not reduce anesthetic requirements in dogs undergoing elective ovariohysterectomy but may reduce signs of pain after surgery. Results also suggest that the objective behavioral score may be a more sensitive measure of acute postoperative pain than traditional numerical pain scores.     

Clinical comparison of recovery from total intravenous anesthesia with propofol and inhalation anesthesia with isoflurane in dogs

The characteristics of recovery from total intravenous anesthesia (TIVA) with propofol and inhalation anesthesia with isoflurane was clinically compared in 149 client-owned dogs that anesthetized for surgical or diagnostic procedures. In all dogs, anesthesia was induced with an intravenous injection of propofol following premedication with acepromazine or diazepam. As a result, 58 dogs anesthetized with propofol-TIVA showed slower but smoother recovery than 91 dogs anesthetized with isoflurane anesthesia. The dogs stood at 34.5 +/- 19.3 and 27.7 +/- 17.2 min after propofol-TIVA and isoflurane anesthesia, respectively. Adverse effects, including hypersalivation, neurologic excitement (paddling, muscle tremor/twitching, opisthotonos) and vomiting/retching, were observed in similar infrequent incidences during the recovery from both anesthetic protocols. Propofol-TIVA is suggested to be an alternative anesthetic protocol for canine practice.     

Respiratory reflexes in response to upper-airway administration of sevoflurane and isoflurane in anesthetized, spontaneously breathing dogs

OBJECTIVE: To evaluate the respiratory effects occurring during administration of sevoflurane or isoflurane to the upper airway in dogs. STUDY DESIGN: A prospective, randomized study. ANIMALS: Twelve healthy adult beagles (6 males, 6 females). METHODS: At least 2 weeks after undergoing permanent tracheostomy, dogs were premedicated with acepromazine-buprenorphine, and anesthesia was induced with thiopental and maintained with alpha-chloralose. The upper airway was functionally isolated so that the inhalant could be administered to the upper airway while dogs were breathing 100% O2 via the tracheostomy. Respiratory reflexes in response to the administration of sevoflurane or isoflurane at concentrations of 1.2, 1.8, and 2.4 times the minimal alveolar concentration (MAC) (administered in 100% O2 at a flow rate of 5 L/min) were recorded. Reflexes in response to administration of each anesthetic were also recorded following upper-airway administration of lidocaine. RESULTS: Respiratory reflexes elicited by upper-airway administration of each anesthetic were characterized by a dose-dependent increase in expiration time, with a resultant decrease in respiratory minute ventilation and increase in end-tidal PCO2. The magnitude of these responses was greater with isoflurane than with sevoflurane at 1.8 and 2.4 MAC. These reflexes were abolished after lidocaine nebulization into the upper airway. CONCLUSION: Isoflurane induces greater reflex inhibition of breathing than does sevoflurane when the anesthetic is inhaled into the upper airway at concentrations used for mask induction.     

Influence of halothane, isoflurane, and sevoflurane on gastroesophageal reflux during anesthesia in dogs

OBJECTIVE: To determine whether maintenance of anesthesia with halothane or sevoflurane is associated with a lower incidence of gastroesophageal reflux (GER) than the use of isoflurane in dogs undergoing orthopedic surgery. ANIMALS: 90 dogs. PROCEDURES: Dogs were evaluated during elective orthopedic surgery. Dogs with a history of vomiting or that had received any drugs that would alter gastrointestinal tract function were excluded from the study. The anesthetic protocol used was standardized to include administration of acepromazine maleate and morphine prior to induction of anesthesia with thiopental. Dogs were allocated to receive halothane, isoflurane, or sevoflurane to maintain anesthesia. A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastroesophageal reflux was defined as an esophageal pH < 4 or > 7.5. RESULTS: 51 dogs had 1 or more episodes of acidic GER during anesthesia. Reflux was detected in 14 dogs receiving isoflurane, 19 dogs receiving halothane, and 18 dogs receiving sevoflurane. In dogs with GER, mean +/- SD time from probe placement to onset of GER was 36 +/- 65 minutes and esophageal pH remained < 4 for a mean of 64% of the measurement period. There was no significant association between GER and start of surgery or moving a dog on or off the surgery table. Dogs that developed GER soon after induction of anesthesia were more likely to regurgitate. CONCLUSIONS AND CLINICAL RELEVANCE: Maintenance of anesthesia with any of the 3 commonly used inhalant agents is associated with a similar risk for development of GER in dogs.     

The effect of four anesthetic protocols on splenic size in dogs

Objective To characterize the effects of four anesthetic protocols on the size of the spleen during surgery in dogs. Study design Prospective experimental trial. Animals Twenty‐four beagle dogs, 1.1 ± 0.3 years of age and weighing 10.9 ± 2.7 kg. Methods Dogs were allocated to receive one of four anesthetic protocols: 1 – pre‐medication with acepromazine and butorphanol, induction with thiopental; 2 – pre‐medication with acepromazine and butorphanol, induction with propofol; 3 – pre‐medication with medetomidine and butorphanol, induction with propofol; and 4 – pre‐medication with medetomidine and butorphanol, induction with ketamine and diazepam. Anesthesia was then maintained with halothane. At laparotomy, the spleen length, width, and height were measured, these were measured again just prior to closure of the abdomen. Splenic area and volume were calculated. Hematocrit and total serum protein (TSP) were measured before and after induction and during laparotomy. Results Splenic volume was greatest after protocol 4 (161.2 ± 40.2 cm³; p < 0.05) and was least after protocol 2. The differences in volume were because of differences in length, width, and height between groups. There was no significant change in area, length, or width over the study period. Hematocrit decreased significantly in all dogs but at different times. The decrease occurred after pre‐medication if acepromazine was administered, at induction following protocol 3 and during surgery following protocol 4. Conclusions If splenic volume is to be minimized during surgery, then acepromazine and propofol should be used in the anesthetic protocol. The administration of medetomidine, diazepam, and ketamine will produce a greater splenic volume. Lack of correlation between hematocrit and spleen size following the anesthetic protocols studied suggests sequestration of red blood cells in nonsplenic sites.     

Transnasal laryngoscopy for the diagnosis of laryngeal paralysis in dogs

Four dogs with clinical signs of laryngeal paralysis and three normal dogs were evaluated with transnasal laryngoscopy. Six of these dogs subsequently underwent standard laryngoscopy. For transnasal laryngoscopy, a video endoscope was passed through the left nasal passage after intramuscular sedation and topical anesthesia. The laryngeal opening was observed during spontaneous ventilation. Laryngeal paralysis was diagnosed in four dogs and was confirmed with traditional laryngoscopy in three dogs. Normal motion of the arytenoid cartilages was present in the other three dogs; however, two required mechanical stimulation of the laryngeal mucosa for full evaluation. Transnasal laryngoscopy provided a means for diagnosing laryngeal paralysis in dogs without general anesthesia.     

Partial neuromuscular block impairs arytenoid abduction during hypercarbic challenge in anesthetized dogs

Objective

To evaluate the effect of two levels of partial neuromuscular block (NMB) on arytenoid abduction, tidal volume (V_T) and peak inspiratory flow (PIF) in response to a hypercarbic challenge in anesthetized dogs.

The effect of four anesthetic protocols on the spleen in dogs

Splenic enlargement following administration of barbiturates has been well described in dogs; other agents have not been investigated. This study aimed to compare the effects of four anesthetic protocols on splenic size.
Twenty-four fasted Beagle dogs scheduled for laparotomy were allocated to one of the four groups. Group 1: acepromazine and butorphanol followed by induction with thiopental; Group 2: acepromazine and butorphanol followed by induction with propofol; Group 3: medetomidine and butorphanol followed by induction with propofol; Group 4: medetomidine and butorphanol followed by induction with ketamine and diazepam. Anesthesia was maintained with halothane in oxygen, intravenous fluids were administered. Splenic length, width and height were measured once when the abdomen was opened and again just prior to closure. Spleens were also traced, the image was digitized, and the area was calculated. PCV and total solids were measured before and after pre-medication, after induction, and each time the spleen was measured. Data were analyzed using a Repeated Measures anova with splenic variables indexed by body surface area and dose of induction agent as a covariate.
Area and width of the spleens were less in the dogs of Groups 2 and 3 than in those of the other groups. Splenic area and length did not change significantly during surgery. Dosage of propofol was not significantly different between Groups 2 and 3. Baseline PCV was not significantly different among groups and decreased significantly in all dogs, but at different times. In Groups 1 and 2, the decrease occurred after pre-medication, in Group 3 at induction, and in Group 4 during surgery. A significant decrease in TS occurred in all groups during surgery.
We concluded that the use of propofol resulted in smaller spleen size during surgery than that following the use of thiopental. Multiple factors influenced the PCV.     

Comparison of Three Clinical Techniques for the Diagnosis of Laryngeal Paralysis in Dogs

Objectives— To evaluate laryngeal function using 3 diagnostic techniques: echolaryngography (EL), transnasal laryngoscopy (TNL), and laryngoscopy per os (LPO).
Study Design— Prospective clinical study.
Animals— Dogs with laryngeal paralysis (n=5) and control dogs (n=10); 5 age- and breed-matched dogs and 5 young, breed-matched dogs.
Methods— Laryngeal function was evaluated in conscious dogs using EL. All examinations were recorded and evaluated by separate, blinded observers upon completion of the study. The methods were compared with a standard evaluation incorporating all clinical knowledge of the case (STD) using sensitivity, specificity, positive, and negative predictive values.
Results— Three dogs with bilateral laryngeal paralysis requiring surgery were diagnosed as unilaterally affected or normal on EL. Three dogs had paradoxic motion on TNL and LPO, 2 of those were considered normal on EL, and 1 had no motion on EL. Paralysis was diagnosed in 1 age-matched and 3 young control dogs on EL. LPO and TNL falsely diagnosed lack of arytenoid movement in 2 age-matched controls and 1 young control. Two age-matched and 1 young control dog were misdiagnosed as paralyzed with TNL and LPO.
Discussion— Direct observation of the larynx allowed better evaluation of laryngeal function compared with EL. TNL did not require induction of anesthesia, but did not improve the ability to assess laryngeal function compared with LPO.
Conclusions— EL was not as effective as direct observation of the larynx. TNL did not improve the evaluation of laryngeal function compared with LPO.
Clinical Relevance— We use LPO combined with knowledge of the clinical history and physical examination to diagnose laryngeal paralysis in preference to EL and TNL.     

Pre-anesthetic meperidine: associated vomiting and gastroesophageal reflux during the subsequent anesthetic in dogs

OBJECTIVE: To determine the effect of meperidine administered prior to anesthesia on the incidence of vomiting before, and gastroesophageal reflux (GER) and regurgitation during, the subsequent period of anesthesia in dogs. STUDY DESIGN: Randomized, controlled trial. ANIMALS: A total of 60 healthy dogs, 4.3 +/- 2.3 years old, and weighing 35.5 +/- 13.1 kg. METHODS: Dogs were admitted to the study if they were healthy, had no history of vomiting, and were scheduled to undergo elective orthopedic surgery. The anesthetic protocol used was standardized to include thiopental and isoflurane in oxygen. Dogs were randomly selected to receive one of the following pre-medications: morphine (0.66 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM), meperidine (8.8 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM) or meperidine alone (8.8 mg kg(-1) IM). A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastro-esophageal reflux was judged to have occurred if there was a decrease in esophageal pH below four or an increase above 7.5. RESULTS: No dogs vomited after the administration of meperidine, but 50% of dogs vomited after the administration of morphine. When compared with morphine, treatment with meperidine alone or combined with acepromazine before anesthesia was associated with a 55% and 27% reduction in absolute risk of developing GER, respectively. Dogs receiving meperidine alone were significantly less sedate than other dogs in the study, and required more thiopental to induce anesthesia. Arterial blood pressure and heart rate were not significantly different between groups at the start of the measurement period. Cutaneous erythema and swelling were evident in four dogs receiving meperidine. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of meperidine to healthy dogs prior to anesthesia was not associated with vomiting and tended to reduce the occurrence of GER, but produced less sedation when compared with morphine. Meperidine is not a useful addition to the anesthetic protocol if prevention of GER is desired.     

THE ROLE OF ULTRASOUND IN THE ASSESSMENT OF LARYNGEAL PARALYSIS IN THE DOG

Forty dogs with clinical signs suggestive of upper respiratory tract disease underwent echolaryngography and laryngoscopy. Laryngoscopy was used as the definitive technique to diagnose laryngeal paralysis. The ultrasound investigation accurately indicated the presence of the paralysis and confirmed the uni- or bilateral nature of the disorder. Findings indicative of laryngeal paralysis included asymmetry or absence of motion of the cuneiform processes (30/30), abnormal arytenoid movement (16/30), paradoxical movement (9/30), caudal displacement of the larynx (2/30) and laryngeal collapse (1/30). Thirty dogs were found to be afflicted with laryngeal paralysis and ten had normal laryngeal motility.     

Traumatic endotracheal intubation in the cat

BACKGROUND: Orotracheal intubation is a commonly performed procedure in the cat, but it is not without complications. Tracheal rupture has been reported in cats, but trauma to the arytenoids from intubation has not been documented. OBSERVATIONS: An otherwise healthy, 5-year-old male domestic shorthair cat presented for total ear canal ablation to resolve intractable otitis media and externa. The cat was premedicated with glycopyrrolate, hydromorphone, and acepromazine. Anesthesia was induced with diazepam and ketamine, and maintained with isoflurane in oxygen. During orotracheal intubation, the larynx was poorly visualized and excessive force was used to perform intubation. Subsequently, blood was observed in the larynx and laryngoscopy revealed a tear lateral to the patient's right arytenoid which had been created during intubation. The larynx was re-intubated normally and the cat suffered no obvious ill effects from the trauma to the larynx. CONCLUSIONS: Direct observation and proper technique must be employed during orotracheal intubation in cats in an attempt to avoid laryngeal trauma.     

An experimental evaluation of castellated laryngofissure and bilateral arytenoid literalisation for the relief of laryngeal paralysis in dogs

The aim of this study was to compare the efficacy of 2 surgical procedures for providing an adequate laryngeal airway in dogs after surgically induced laryngeal paralysis. The laryngeal function of 10 healthy, adult experimental dogs was assessed by clinical examination, laryngoscopy, arterial blood gas measurement and analysis of tidal breathing flow-volume loops before, and after, bilateral recurrent laryngeal neurectomy. A castellated laryngofissure with vocal fold resection was done on 5 dogs and bilateral arytenoid cartilage lateralisation performed on the remaining 5 dogs. Six weeks later, the laryngeal function of the 10 dogs was reassessed, before the dogs were killed and a necropsy performed. The visible changes in laryngeal structure were recorded. Both surgical procedures alleviated some of the airway obstruction caused by the bilateral recurrent laryngeal neurectomy, but bilateral arytenoid cartilage lateralisation produced more consistent clinical improvement, a wider rima glottidis, increased inspiratory air flow and a significant increase in post-operative arterial oxygen tension.     

Neuromuscular pedicle graft for restoration of arytenoid abductor function in dogs with experimentally induced laryngeal hemiplegia

Left laryngeal hemiplegia was induced by resection of the left recurrent laryngeal nerve in 12 dogs. A neuromuscular pedicle graft formed from the first cervical nerve and sternothyroideus muscle was transplanted after 1 week to the denervated cricoarytenoideus dorsalis muscle in 8 dogs. The remaining 4 dogs served as controls. Left arytenoid abduction was blindly evaluated by laryngoscopy with video photography at time 0, at 1 week, and at 19 weeks in all dogs. At 19 weeks, biopsy specimens of the left cricoarytenoideus dorsalis muscle and the neuromuscular pedicle were taken from 4 of the treatment dogs, and biopsy specimens of the left cricoarytenoideus dorsalis muscle were taken from the 4 control dogs. All biopsy specimens were blindly evaluated by histologic and histochemical examination. At 36 to 44 weeks, the remaining 4 treatment dogs, from which biopsy specimens had not been taken, were reevaluated by use of laryngoscopy with video photography. Complications and difficulties encountered during surgery included hemorrhage in the area of the cricoarytenoideus dorsalis muscle, location of a branch of the first cervical nerve that was long enough to prevent tension at the graft site, orientation of the muscle pedicle in the cricoarytenoideus dorsalis muscle without the use of an operating microscope, and preservation of the terminal portion of the first cervical nerve while forming the neuromuscular pedicle. Results of the arytenoid movement evaluations revealed improvement in arytenoid abductor function in the treatment group, compared with that in the control group at 19 weeks. Arytenoid abduction in the treatment group at this time, however, was still significantly decreased (P less than 0.05), compared with presurgical movement evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)