Effects of suture tension during unilateral cricoarytenoid lateralization on canine laryngeal resistance in vitro

Evaluation of two unilateral laryngoplasty techniques and their effect on arytenoid cartilage abduction in cats

OBJECTIVES

The aim of this study was to evaluate two unilateral laryngoplasty (arytenoid lateralisation) techniques for use in the surgical management of laryngeal paralysis in cats.

METHODS

Left cricoarytenoid abduction (lateralisation) was performed in 20 ex vivo cat larynges; 10 following complete cricoarytenoid disarticulation (group LAA-dis) and 10 following no cricoarytenoid disarticulation (group LAA-nodis). For both groups, left arytenoid abduction (LAA) was measured in the resting and postoperative larynges using image analysis software. Measurements were evaluated using the Mann-Whitney U-test. For both groups, dorsal images of the postoperative larynges were assessed visually for evidence of epiglottic coverage of the entrance to the larynx.

RESULTS

The mean percentage increase in LAA was 311.5% and 199.4% (P <0.006) for group LAA-dis (complete cricoarytenoid disarticulation) and group LAA-nodis (no cricoarytenoid disarticulation), respectively. In both groups, there was no evidence of a lack of epiglottic coverage of the entrance of the larynx for any of the postoperative larynges.

CONCLUSIONS AND RELEVANCE

Placement of a single, tensioned suture between the muscular process of the left arytenoid cartilage and the caudolateral aspect of the ipsilateral cricoid cartilage (unilateral cricoarytenoid lateralisation) resulted in abduction of the left arytenoid cartilage and a corresponding increase in the area of the rima glottidis on the operated side. The clinical significance of the difference in outcome between left cricoarytenoid abduction following complete cricoarytenoid disarticulation and abduction following no cricoarytenoid disarticulation remains unclear, and both might be considered appropriate for the surgical management of laryngeal paralysis in the cat.

Description and evaluation of a novel transoral endoscopic arytenopexy in canine cadavers

OBJECTIVE

To describe the transoral endoscopic arytenopexy (TEA) and evaluate its effects on the rima glottis area (RGA) and laryngeal epiglottic-glottic seal (LEGS). We hypothesize the TEA will be a feasible surgical technique and the TEA will provide a significant increase in RGA with minimal change to the LEGS.

STUDY DESIGN

Canine cadaveric model.

ANIMALS

Fifteen medium- to large-breed canine cadavers.

METHODS

Endoscopic photos of the larynx were taken with the epiglottis open for baseline RGA measurement and closed for baseline measurement of exposed RGA and LEGS. A custom endoscopic gag port (EGP) facilitated the TEA, performed by suturing the lateral aspect of the left arytenoid soft tissues to adjacent pharyngeal wall across the piriform recess. Endoscopic photos were repeated to measure changes in RGA and LEGS. A computerized planimetric analysis program was used to calculate baseline RGA and LEGS. The RGA was reported in % change from baseline. The LEGS was reported as intact or altered. A nonparametric Wilcoxon signed-rank test was used to compare baseline to post-TEA RGA.

RESULTS

The mean baseline RGA was 0.52 ± 0.28 cm³ and mean post-TEA RGA was 0.78 ± 0.37 cm³ (p-value < .0001). The LEGS remained intact post-TEA in all cadavers.

CONCLUSIONS

The TEA was technically feasible and resulted in an increase in RGA while maintaining the LEGS.

CLINICAL SIGNIFICANCE

The TEA may provide a minimally invasive addition to the established techniques for reducing airway resistance while minimizing the impact on the LEGS.

Effects of a novel, 3D printed bilateral arytenoid abductor on canine laryngeal airway resistance ex vivo

Background

Laryngeal paralysis is a disease process most commonly seen in older, large breed dogs. When both arytenoid cartilages are affected dogs can develop life-threatening respiratory compromise, therefore surgical intervention is recommended. While there are multiple surgical procedures that have been described to treat laryngeal paralysis, there remains a considerable risk for postoperative complications, most commonly aspiration pneumonia. The objective of this ex vivo experimental study was to evaluate the effects of a novel, 3D printed bilateral arytenoid abductor on laryngeal airway resistance in canine cadaver larynges. Laryngeal airway resistance was calculated for each specimen before (control) and after placement of a 3D printed, bilateral arytenoid abductor. The airway resistance was measured at an airflow of 10 L/min with the epiglottis closed and at airflows ranging from 15 L/min to 60 L/min with the epiglottis open. The effects of the bilateral arytenoid abductor on laryngeal airway resistance were evaluated statistically.

Results

With the epiglottis open, median laryngeal airway resistance in all larynges with a bilateral arytenoid abductor were significantly decreased at airflows of 15 L/min (0.0cmH2O/L/sec), 30 L/min (0.2cmH2O/L/sec), and 45 L/min (0.2cmH2O/L/sec) compared to the controls 15 L/min (0.4cmH2O/L/sec; P = 0.04), 30 L/min (0.9cmH2O/L/sec; P = 0.04), and 45 L/min (1.2cmH2O/L/sec; P = 0.04). When the epiglottis was closed, there was no significant difference in laryngeal resistance between the control (18.8cmH₂O/L/sec) and the abducted larynges (18.1cmH₂O/L/sec; P = 0.83).

Conclusions

Placement of a bilateral arytenoid abductor reduced laryngeal resistance in canine cadaver larynges compared to the controls when the epiglottis was open. With the epiglottis closed, there was no loss of laryngeal resistance while the device abducted the arytenoid cartilages. The results of this ex vivo study is encouraging for consideration of further evaluation of the bilateral arytenoid abductor to determine an appropriate material and tolerance of this device in vivo.

Comparison of immediate and short-term outcomes of cricoarytenoid and thyroarytenoid lateralization in dogs with idiopathic laryngeal paralysis

OBJECTIVE

To compare the immediate and short-term outcomes of thyroarytenoid lateralization (TAL) and cricoarytenoid lateralization (CAL) for the treatment of canine laryngeal paralysis in dogs.

STUDY DESIGN

A prospective, clinical trial.

ANIMALS

Fourteen client-owned dogs referred to our hospital because of bilateral laryngeal paralysis.

METHODS

Dogs with confirmed laryngeal paralysis were randomly assigned to the CAL or TAL group. Video images of the rima glottidis obtained preoperatively, immediately postoperatively (t0), and 15 days postoperatively (t1) were digitized. The rima glottidis area was measured using image-analysis software. An increase in the rima glottidis area was expressed as a percentage of the preoperative area.

RESULTS

The rima glottidis area increased by a mean of 152% at t0 and 127% at t1 for the TAL group and 205% at t0 and 199% at t1 for the CAL group compared with preoperative values. The increase in the rima glottidis area differed (P < .05) between the 2 groups at all postoperative time points. A reduction of the area occurred at t1 in both groups. There was no difference between t0 and t1 (P > .05) in the CAL group but there was a large difference (P < .05) in the TAL group.

CONCLUSION

Cricoarytenoid lateralization and TAL were both effective for surgical abduction of the arytenoid cartilage. Although a reduction (P < .05) in the rima glottidis area occurred in the TAL group at t1, we observed no associated clinical signs.

CLINICAL SIGNIFICANCE

Cricoarytenoid lateralization and TAL result in good short-term outcomes in dogs with laryngeal paralysis.

Effect of Cricoarytenoid Joint Preservation and Suture Tension on Arytenoid Lateralization

The objective of this experimental study was to evaluate the effects of cricoarytenoid (CA) joint preservation versus disarticulation on rima glottidis (RG) area with the epiglottis open and closed under both low and high suture tension. Canine cadaver larynges were used. A unilateral arytenoid lateralization (UAL) was performed with low or high suture tension and with the CA joint preserved or disarticulated. Rima glottidis area was measured with the epiglottis in an open and closed position. Results indicated that RG area was increased over baseline when UAL was performed with both low and high suture tension when the epiglottis was in an open position. High suture tension resulted in a greater increase in RG area compared to low suture tension, both when the CA was preserved and disarticulated. There was no difference in RG area when the CA was disarticulated versus preserved at either suture tension. Rima glottidis area was not significantly increased over baseline when the epiglottis was in a closed position except in the group with CA joint preservation and high suture tension. Although this study suggests that UAL can be performed with or without CA disarticulation, further studies are warranted before UAL without CA disarticulation can be recommended clinically.

Minimally invasive unilateral arytenoid lateralization in dogs: A cadaveric study

The aim of this study was to develop a minimally invasive thyroarytenoid lateralization technique (MITAL). Eleven unilateral MITAL procedures were performed on 11 canine cadavers. Two hypodermic needles were passed through the skin into the lumen of the larynx, penetrating the thyroid and arytenoid cartilages. Suture material was passed through the needles to lateralize the arytenoid cartilage. A rigid endoscope was used to visualize needle insertion and suture material placement. A key-hole approach to the larynx was performed and the suture material was knotted on the lateral aspect of the thyroid cartilage. The change in the rima glottidis area was recorded as were the duration of the procedure and complications encountered. The landmarks for needle insertion were easily palpated, and a significant increase in the area of the rima glottidis was documented after performing unilateral MITAL. In conclusion, unilateral MITAL is a quick, minimally invasive procedure which increases the area of the rima glottidis in cadaveric dogs.

Intralaryngeal thyroarytaenoid lateralisation using the Fast-Fix 360 system: a canine cadaveric study

Introduction

Laryngeal paralysis is a condition in which failure of arytaenoid abduction results in a reduced rima glottidis cross-sectional area. The most commonly performed surgical techniques rely on unilateral abduction of the arytaenoid, requiring a lateral or ventral surgical approach to the larynx.

Aims and objectives

The aim of the study was to investigate a novel minimally invasive intralaryngeal thyroarytaenoid lateralisation technique, using the Fast-Fix 360 meniscal repair system.

Materials and methods

Larynges were harvested from large breed canine cadavers. With the aid of Kirschner wires placed between the centre of the vocal process and the centre of an imaginary line between the cranial thyroid fissure and the cricothyroid articulation, the mean insertion angle was calculated.

Results

The Fast-Fix 360 delivery needle inserted intralaryngeally (n=10), according to a simplified insertion angle (70°), resulted in thyroid penetration (>2.5 mm from margin) in all patients. The Fast-Fix was applied unilaterally at 70° with the first toggle fired on the lateral aspect of the thyroid cartilage and inside the laryngeal cavity on retraction. The suture was tightened. Preprocedural (61.06±9.21 mm2) and postprocedural (138.37±26.12 mm2) rima glottidis cross-sectional area was significantly different (P<0.0001). The mean percentage increase in rima glottidis cross-sectional area was 125.96 per cent (±16.54 per cent).

Conclusion

Intralaryngeal thyroarytaenoid laterlisation using the Fast-Fix 360 meniscal repair system ex vivo increased the rima glottidis cross-sectional area significantly.

Changes in rima glottidis area and lack of laryngeal epiglottic-glottic seal after unilateral cricoarytenoid lateralization ex vivo

OBJECTIVE

To evaluate variation in rima glottidis (RG) area and lack of epiglottic-glottic seal (LEGS) of the canine larynx associated with different suture anchor points in the arytenoid and cricoid cartilages, dissection of the cricoarytenoid joint capsule, section of the interarytenoid band, and disarticulation of the cricothyroid joint.

STUDY DESIGN

Experimental study.

ANIMALS

Cadaveric canine larynges (n = 18).

METHODS

Larynges were assigned to 2 groups: group 1 = intact cricothyroid articulation and group 2 = cricothyroid articulation sharply sectioned. In each group, the arytenoid cartilage was lateralized successively as follows: (a) intact cricoarytenoid articulation, (b) cricoarytenoid articulation sharply sectioned, and (c) division of the interarytenoid band. Each variation was performed initially with the suture passed dorsally into the cricoid cartilage then with the suture passed laterally. Each time, the increase of rima glottis area (%) and the LEGS (mm(2) ) were measured.

RESULTS

Rima glottis area (RGA): when the suture was placed dorsally, division of the interarytenoid band resulted in a significant increase in RGA compared with groups with an intact band. Laryngeal distortion: when the suture through the cricoid cartilage was dorsal, LEGS increased with section of the cricothyroid articulation, dissection of cricoarytenoid articulation, and division of the interarytenoid band.

CONCLUSION

Unilateral arytenoid lateralization results in some degree of LEGS with a misalignment of the epiglottis over the RG. Our results revealed that the optimal RGA associated with the minimal LEGS was obtained with dorsal placement of a cricoarytenoid suture when the cricothyroid joint and the interarytenoid band were intact.

Laryngeal disease in dogs and cats

The most common disease process involving the larynx is laryngeal paralysis, which occurs much more frequently in dogs than in cats. Diagnosis of laryngeal paralysis requires close attention to anesthetic plane and coordination of respiratory effort with laryngeal motion. Surgical arytenoid lateralization improves respiration and quality of life in dogs with laryngeal paralysis; however, aspiration pneumonia is a recognized complication, and generalized neuropathy can progress. Laryngeal collapse can result from any cause of chronic upper airway obstruction, but is most often associated with unaddressed brachycephalic airway syndrome. Laryngeal neoplasia, while generally uncommon, occurs more frequently in cats than in dogs.

Less invasive unilateral arytenoid lateralization: a modified technique for treatment of idiopathic laryngeal paralysis in dogs: technique description and outcome

OBJECTIVE

To (1) describe a modification of conventional unilateral cricoarytenoid lateralization (UCAL), called less-invasive unilateral cricoarytenoid lateralization (LI-UCAL) for treatment of idiopathic laryngeal paralysis (LP); (2) report clinical outcome of LI-UCAL; and (3) describe the effect of early discharge after surgery.

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Dogs (n = 22).

METHODS

Medical records (January 2009 to October 2011) of dogs diagnosed with idiopathic LP that had LI-UCAL were reviewed. Signalment, clinical signs, laboratory tests, imaging, concurrent medical conditions, information from the anesthesia record, and hospitalization time were documented. Follow-up was obtained by direct examination, questionnaire, and review of medical records from referring veterinarians.

RESULTS

Dogs included in the study had variable degrees and duration of respiratory distress before surgery. Median surgery time was 32 minutes. Median hospitalization was 6 hours, and median follow-up was 427 days. Long-term respiratory function, as reported by owners at last follow-up, improved in 95.5% of dogs after surgery; exercise tolerance improved by 90%. Major complications included death secondary to aspiration pneumonia (9%), aspiration pneumonia from which dogs recovered within 3 days after administration of antimicrobials (9%), and development of right-sided laryngeal collapse that required right sided LI-UCAL (4.5%). At long-term follow-up, 95.5% of owners were satisfied with the surgical outcome.

CONCLUSION

LI-UCAL is a feasible surgical technique and resulted in improvement of clinical signs related to LP. Calm recoveries without adverse effects such as respiratory distress were associated with early discharge. LI-UCAL could be considered an alternative to conventional UCAL.

Video-assisted unilateral cricoarytenoid laryngoplasty in 14 dogs with bilateral idiopathic laryngeal paralysis

BACKGROUND

Unilateral cricoarytenoid laryngoplasty is commonly performed for treatment of idiopathic laryngeal paralysis in dogs. Determination of the appropriate tension applied to the suture can be difficult, particularly for the novice surgeon.

OBJECTIVE

To describe a technique for video-assisted unilateral cricoarytenoid laryngoplasty (VAUCAL) and to report short-term outcome in dogs undergoing VAUCAL.

ANIMALS AND METHODS

Dogs (n = 14) with bilateral idiopathic laryngeal paralysis undergoing VAUCAL between August 2011 and May 2013 were evaluated. A cricoarytenoid suture was tensioned under video observation of the rima glottidis using a 5-mm rigid endoscope. Real-time visualization of arytenoid abduction during suture tensioning, and final arytenoid position were assessed. Requirement for additional intravenous anesthestic, intra- and post-operative complications and short-term outcomes were documented.

RESULTS

Adequate, real-time visualization of the larynx during tensioning of the cricoarytenoid suture was accomplished in 13/14 dogs. Additional intravenous anesthesia was required in 5/14 dogs to facilitate reintubation. Final arytenoid position was considered inadequate in two dogs on post-operative trans-oral laryngeal examination. Recurrence of clinical signs occurred in one dog three months following initial surgery. Owner outcome was deemed good (n = 8) or excellent (n = 6).

CONCLUSIONS

VAUCAL is a feasible technique to permit direct real-time visualization of the larynx during tensioning of the cricoarytenoid suture, and enables assessment of final arytenoid position intra-operatively by the operating surgeon.

CLINICAL IMPORTANCE

VAUCAL allows the operating surgeon to assess arytenoid abduction intra-operatively, at the time of knot placement. This technique may be particularly useful for the novice surgeon or surgeon in training.

Effects of unilateral arytenoid lateralization technique and suture tension on airway pressure in the larynx of canine cadavers

OBJECTIVE

To evaluate effects of the arytenoid lateralization technique and suture tension on airway pressure in the canine larynx.

SAMPLE

7 canine cadaver larynges.

PROCEDURES

Negative pressure was elicited aboral to the larynx. Airway pressure was measured at airflows of 15 to 120 L/min before and after thyroarytenoid lateralization (TAL), cricoarytenoid lateralization (CAL), and combined TAL and CAL (cricothyroarytenoid lateralization [CTAL]) at 100 and 500 g of suture tension and with sectioning of the sesamoid cartilage (SSC) and disarticulation of the cricothyroid joint (DCTJ). Rima glottidis area (RGA) was measured. Effects of technique, modification, and suture tension on pressure and RGA were evaluated statistically.

RESULTS

Increased suture tension significantly reduced airway pressure for TAL at 30 L/min, CAL at 45 to 120 L/min, and CAL after SSC and DCTJ at 60, 75, and 105 to 120 L/min. The CAL and CTAL caused significantly lower airway pressures than did TAL > 30 L/min, but SSC and DCTJ did not significantly reduce pressure. All procedures, except TAL at 100 g of tension, resulted in a significant RGA increase from baseline. The CAL and CTAL caused a significantly greater RGA than did TAL. For TAL at 100 g of tension, SSC significantly increased RGA.

CONCLUSIONS AND CLINICAL RELEVANCE

CAL and CTAL caused lower airway pressures than did TAL. No significant pressure differences were detected between CAL and CTAL; SSC and DCTJ had little effect on pressure. Pressure may be a more sensitive indicator of airflow than is RGA in the larynx of canine cadavers.

Intraoperative evaluation of the larynx following unilateral arytenoid lateralization for acquired idiopathic laryngeal paralysis in dogs

The purposes of this study were to describe a modified surgical technique in which intraoperative extubation was performed to evaluate abduction of the arytenoid cartilage prior to tying the suture and to assess outcome and complication rates associated with this procedure. Medical records from 30 client-owned dogs with acquired idiopathic laryngeal paralysis were retrospectively reviewed. All clients were contacted by telephone to obtain follow-up information regarding their dog. Six of the 30 surgeries required additional dissection (primarily around the craniodorsal aspect of the cricoarytenoid joint) after the initial intraoperative laryngeal examination. The procedures in 29 of the 30 dogs were deemed a success by the owners. Three (10%) dogs developed postoperative aspiration pneumonia. One of these dogs required long-term antibiotic therapy. Twenty-nine dogs returned to normal activity, and none of the dogs had any exercise intolerance associated with respiratory difficulties. Three owners reported that their dogs were able to swim, and one dog hunted postoperatively. Results of this study suggest that intraoperative laryngeal examination may help limit postoperative complications by allowing for direct, intraoral visualization of the arytenoid cartilage. This enables a surgeon to modify the soft tissue dissection around the cricoarytenoid joint to ensure that adequate abduction is apparent.