A low-cost portable simulator of a domestic cat larynx for teaching endotracheal intubation

ObjectiveTo design and construct an affordable simulator of the cat larynx for training intubation maneuvers and to share the designs for its fabrication.Study designResearch and development study.AnimalsA domestic cat.MethodsThe cadaver of a cat, dead by natural causes, was frozen in sternal recumbency with the neck extended and the mouth wide open. A computed tomography image was acquired and used to construct a digital three-dimensional (3D) model of the pharynx and trachea. A digitally adapted model was 3D-printed and used to generate a silicone model of these structures, which was placed within a wooden container. The quality of the simulator was assessed by 46 veterinary anesthesiologists and veterinarians with experience in tracheal intubation maneuvers, and their opinions were obtained through an anonymous questionnaire.ResultsSeveral preliminary prototypes were assessed regarding stability, texture and cost. Finally, a silicone model of a cat larynx (LaryngoCUBE) was produced and encased in a wooden container. Results from the questionnaire showed high scores regarding anatomy, tissue texture and intubation maneuver realism, compared with the real procedure.Conclusionsand clinical relevance Use of LaryngoCUBE as a training tool may improve the skills of students and reduce the use of animals for teaching endotracheal intubation. Blueprints and computational models are provided online so that the simulator can be fully reproduced.     

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.     

Effect of intravenous fentanyl on cough reflex and quality of endotracheal intubation in cats

ObjectiveTo assess the effects of intravenous (IV) fentanyl on cough reflex and quality of endotracheal intubation (ETI) in cats.Study designRandomized, blinded, negative controlled clinical trial.AnimalsA total of 30 client-owned cats undergoing general anaesthesia for diagnostic or surgical procedures.MethodsCats were sedated with dexmedetomidine (2 μg kg^–1 IV), and 5 minutes later either fentanyl (3 μg kg^–1, group F) or saline (group C) was administered IV. After alfaxalone (1.5 mg kg^–1 IV) administration and 2% lidocaine application to the larynx, ETI was attempted. If unsuccessful, alfaxalone (1 mg kg^–1 IV) was administered and ETI re-attempted. This process was repeated until successful ETI. Sedation scores, total number of ETI attempts, cough reflex, laryngeal response and quality of ETI were scored. Postinduction apnoea was recorded. Heart rate (HR) was continuously recorded and oscillometric arterial blood pressure (ABP) was measured every minute. Changes (Δ) in HR and ABP between pre-intubation and intubation were calculated. Groups were compared using univariate analysis. Statistical significance was set as p < 0.05.ResultsThe median and 95% confidence interval of alfaxalone dose was 1.5 (1.5–1.5) and 2.5 (1.5–2.5) mg kg^–1 in groups F and C, respectively (p = 0.001). The cough reflex was 2.10 (1.10–4.41) times more likely to occur in group C. The overall quality of ETI was superior in group F (p = 0.001), with lower laryngeal response to ETI (p < 0.0001) and ETI attempts (p = 0.045). No differences in HR, ABP and postinduction apnoea were found.Conclusions and clinical relevanceIn cats sedated with dexmedetomidine, fentanyl could be considered to reduce the alfaxalone induction dose, cough reflex and laryngeal response to ETI and to improve the overall quality of ETI.     

Use of neuromuscular blockade with rocuronium bromide for intubation in cats

ObjectiveTo determine whether neuromuscular blockade with rocuronium bromide (RB) would improve endotracheal intubation (EI) conditions in comparison with topical lidocaine hydrochloride (LH).Study designRandomized prospective study.AnimalsForty seven healthy cats of unspecified breed, aged 17 ± 11 months and weighing 2.8 ± 0.8 kg, undergoing elective procedures.MethodsAnesthesia was induced with xylazine (XZ) (1.1 mg kg^?1 IM) and tiletamine‐zolazepam (XTZ) (7 mg kg^?1 IM) and EI was attempted. Cats which could not be intubated at the first attempt (n = 34), were randomly medicated with either 0.1 mL LH 10% spray on the laryngeal mucosa (n = 17) or 0.6 mg kg^?1 intravenous RB (n = 17). Sixty seconds later, a second attempt at EI was performed. The effect of both drugs was assessed using a previously published scale (Sandor Agoston). EI conditions associated with laryngoscopy, vocal cord position and movement, cough, patient movement, time and attempts needed in order to perform EI were recorded. Heart rate and end‐expired CO₂ concentration were monitored.ResultsGroups were comparable in age, weight, gender and hematological parameters. Clinically acceptable EI conditions were not significantly different between RB and LH assisted groups (p = 0.31). However, there was a significant difference in cough, vocal cord movement and position between the RB and the LH groups. The group intubated at the first attempt and receiving neither RB nor LH coughed persistently (11/13). The cats receiving RB had to be ventilated for 10–28 minutes.Conclusions and clinical relevanceThe present study shows that, when used in cats anesthetized with XTZ, RB paralyzes the internal laryngeal muscles keeping the vocal cords in an intermediate position (paramedial) 60 seconds after being administered. RB is an effective alternative to LH to overcome the airway protective reflexes when performing EI but requires ventilatory support until the paralysis wears off.     

Multiple cutaneous histiocytomas in a cat

A 15-year-old domestic long haired cat developed nodular cutaneous masses over the right shoulder that were removed surgically. Similar masses developed in multiple cutaneous sites over the following three years. In each case, the lesions were characterized by diffuse dermal infiltration by histiocytic cells with a low mitotic rate and evidence of epidermotropism. The neoplastic population uniformly expressed class II molecules of the Major Histocompatibility Complex, but did not express the T and B lymphoid markers CD3 and CD79. Perivascular aggregates of CD3⁺ T lymphocytes were located at the deep margins of the tumour nodules. The clinical, histopathological and immunohistochemical features of these tumours are consistent with cutaneous histiocytoma. This tumour has not been previously well-documented in the cat.     

Identification of domestic cat hepadnavirus from a cat blood sample in Japan

The hepatitis B virus (Hepadnaviridae) induces chronic hepatitis and hepatic cancer in humans. A novel domestic cat hepadnavirus (DCH) was recently identified in several countries, however, the DCH infection status of cats in Japan is unknown. Therefore, we investigated the DCH infection rate of 139 cat samples collected in Japan. We identified one positive blood sample (0.78%) from a 17-year-old female cat with chronically elevated alanine aminotransferase. Phylogenetic analysis demonstrated that the DCH strain identified in this study is genetically different from strains in other countries. Further investigations are required to elucidate the evolution of DCH and the impact of DCH infection on hepatic diseases in domestic cats.     

Staphyloma in a cat

A unilateral scleral staphyloma in an 18-month-old, female spayed Domestic Short-haired cat was treated with excision, primary closure and fascial graft. Other ocular abnormalities noted on examination included iris coloboma, anterior cortical cataract, focal lens equator flattening and retinal dysplasia. The staphyloma was presumed to be congenital in origin.     

Incomplete tracheal intussusception in a dog

An 18-year-old male miniature poodle had a chronic nonproductive cough. On radiographic examination, an opacification resembling a foreign body was noticed within the trachea at the level of the sixth cervical vertebra. When the trachea was examined endoscopically, a circumferential flap-like lesion was found. To differentiate the invagination from an annular mass, thoracic computed tomography (CT) of the trachea was performed. There was cranial displacement and invagination of a tracheal segment creating the flap-like lesion. Tracheal intussusception should be considered as a cause of an annular tracheal mass.     

Nocardial peritonitis in a cat

Objective To illustrate a successfully managed case of nocardial peritonitis in a cat.
Design Case report.
Animal An 8 year old neutered male Burmese cat presented for nonspecific signs of depression, anorexia, pallor and mild dehydration. Pyrexia, loss of weight and abdominal distension developed despite treatment with amoxycillin-clavulanate and supportive therapy.
Procedure Various medical and surgical procedures were used.
Results Haematology revealed severe inflammatory left shift. Biochemistry showed mild prerenal azotemia. A "ground glass" appearance to the abdomen was seen on radiographs. Fluid collected by abdominocentesis contained "sulphur granules" and had characteristics of a septic exudate. Laparotomy allowed drainage of peritoneal fluid and extensive lavage of the peritoneal cavity. Culture of the fluid revealed Nocardia sp. Sensitivity testing resulted in a change of antimicrobial therapy to trimethoprim-sulphadiazine.
Conclusion Response to surgical drainage and change in antibacterial therapy was excellent. No toxic side effects were encountered during the 3 months course of trimethoprim-sulphonamide. The cat made a complete recovery.     

The effects of two endotracheal tube cuff inflation pressures on liquid aspiration and tracheal wall damage in horses

OBJECTIVE: To investigate the effect of endotracheal tube cuff inflation pressure on the occurrence of liquid aspiration and tracheal wall damage. STUDY DESIGN: Prospective, randomized experimental study. ANIMALS: Ten healthy horses, weighing 535 +/- 55 kg. METHODS: Horses were anesthetized, orotracheally intubated, placed in dorsal recumbency, and maintained on isoflurane in oxygen with controlled ventilation for 175 +/- 15 minutes. The horses were randomly assigned to an endotracheal cuff pressure of 80-100 or 120 cm H2O. The cuff pressure was continuously monitored and maintained at a constant pressure. Methylene blue in saline was instilled proximal to the cuff. After euthanasia, the trachea was opened distal to the endotracheal tube tip to check for evidence of dye leaking past the cuff. The cervical trachea was then resected and opened longitudinally for gross and histologic examinations. RESULTS: No blue staining was found distal to the cuff in any horse. Visual examination of the tracheal mucosa revealed hyperemic and hemorrhagic lesions at the site of the cuff contact. Histologic changes included epithelium attenuation or erosion, submucosal neutrophilic infiltration, and submucosal hemorrhages. Lesions were absent or less extensive in the lower cuff pressure group as compared to the high cuff pressure group. CONCLUSIONS: The endotracheal tube cuff produced a seal sufficient to prevent leakage in both groups. Tracheal wall damage was more severe and occurred more frequently in the higher cuff pressure group. CLINICAL RELEVANCE: Tracheal mucosal damage induced by cuff inflation is pressure-dependent. Cuff pressure monitoring is recommended.     

Evaluation of laryngeal mask as an alternative to endotracheal intubation in cats anesthetized under spontaneous or controlled ventilation

OBJECTIVE: To compare the cardiorespiratory effects and incidence of gastroesophageal reflux with the use of a laryngeal mask airway (LMA) or endotracheal tube (ET) in anesthetized cats during spontaneous (SV) or controlled ventilation (CV). STUDY DESIGN: Prospective randomized experimental trial. ANIMALS: Thirty-two adult crossbred cats, weighing 2.7 +/- 0.4 kg. METHODS: The cats were sedated with intramuscular (IM) methotrimeprazine (0.5 mg kg(-1)) and buprenorphine (0.005 mg kg(-1)), followed 30 minutes later by induction of anesthesia with intravenous (IV) thiopental (12.5-20 mg kg(-1)). An ET was used in 16 cats and an LMA in the remaining 16 animals. Anesthesia was maintained with 0.5 minimum alveolar concentration (0.6%) of halothane in oxygen using a Mapleson D breathing system. Cats in both groups were further divided into two equal groups (n = 8), undergoing either SV or CV. Neuromuscular blockade with pancuronium (0.06 mg kg(-1)) was used to facilitate CV. Heart and respiratory rates, direct arterial blood pressure, capnometry (PE'CO2) and arterial blood gases were measured. Gastric reflux and possible aspiration was investigated by intragastric administration of 5 mL of radiographic contrast immediately after induction of anesthesia. Cervical and thoracic radiographs were taken at the end of anesthesia. Data were analyzed using anova followed by Student-Newman-Keuls, Kruskal-Wallis or Friedman test where appropriate. RESULTS: Values for PaCO2 and PE'CO2 were higher in spontaneously breathing cats with the LMA when compared with other groups. Values of PaO2 and hemoglobin oxygen saturation did not differ between groups. Gastroesophageal reflux occurred in four of eight and two of eight cats undergoing CV with ET or LMA, respectively. There was no tracheal or pulmonary aspiration in any cases. CONCLUSIONS AND CLINICAL RELEVANCE: The use of an LMA may be used as an alternative to endotracheal intubation in anesthetized cats. Although aspiration was not observed, gastric reflux may occur in mechanically ventilated animals.     

Comparison of blind and endoscopic-guided orotracheal intubation on laryngeal and tracheal damage in domestic rabbits (Oryctolagus cuniculus)

ObjectiveTo compare blind and endoscopic-guided techniques for orotracheal intubation in rabbits and the number of intubation attempts with laryngeal/tracheal damage.Study designProspective, randomized experimental study.AnimalsA total of 24 healthy, intact female New Zealand White rabbits, weighing 2.2 ± 0.2 kg (mean ± standard deviation).MethodsRabbits were randomly assigned to blind (group B) or endoscopic-guided (group E) orotracheal intubation with a 2.0 mm internal diameter uncuffed tube. Intramuscular (IM) alfaxalone (7 mg kg^–1), hydromorphone (0.1 mg kg^–1) and dexmedetomidine (0.005 mg kg^–1) were administered, and additional IM alfaxalone (3–5 mg kg^–1) and dexmedetomidine (0.025 mg kg^–1) were administered to rabbits with strong jaw tone. An intubation attempt was defined as the advancement of the endotracheal tube from the incisors to the laryngeal entrance. Tracheal intubation was confirmed via capnography and anesthesia was maintained with isoflurane for 2 hours. Following euthanasia, laryngeal and tracheal tissues were submitted for histopathology. Quality of anesthesia for orotracheal intubation, intubation procedure and tissue damage were numerically scored. Data were analyzed using Poisson regression, Spearman’s correlation, t test, mixed anova, Mann–Whitney U test, Friedman and Chi square tests as appropriate.ResultsMedian (range) intubation attempts were 2 (1–8) and 1 (1–3) for groups B and E, respectively. More rabbits in group E (91.6%) required additional alfaxalone and dexmedetomidine than in group B (16.7%). Median (range) cumulative histopathology scores were 6 (3–10) and 6 (2–9) for groups B and E, respectively. Scores were highest in the cranial trachea, but there was no difference between groups and no correlation between laryngeal/tracheal damage and the number of intubation attempts.Conclusions and clinical relevanceBoth orotracheal intubation techniques were associated with laryngeal/tracheal damage. Although blind orotracheal intubation was associated with a higher number of attempts, the tissue damage was similar between groups.     

B-cell conjunctival lymphoma in a cat

A bilateral conjunctival neoplasm was surgically removed from a 13-year-old Domestic Short-haired female cat and examined by histopathology. The neoplasm was infiltrative, nonencapsulated and composed of large sheets of densely packed, round to polygonal cells. Neoplastic cells were variably sized with scant to modest amounts of cytoplasm and oval to round nuclei. On immunohistochemistry the neoplastic cells stained positively for BLA.36 and negative for CD-3 antibodies. On the basis of histopathology and immunohistochemical findings, a diagnosis of conjunctival B-cell lymphoma was made. This is the first case with immunohistochemical characterization of conjunctival lymphoma in a cat.     

Tracheal trauma and pneumonia secondary to endotracheal intubation in a horse undergoing general anaesthesia,computerised tomography and myelography

Endotracheal intubation is commonly performed in horses undergoing general anaesthesia to avoid fluid aspiration and provide mechanical ventilation and inhalational anaesthetic agents. Secondary laryngeal and tracheal trauma following intubation is not rare. This case report describes the successful treatment of a horse with laryngeal and tracheal trauma secondary to intubation during myelography. Based on other clinical reports and clinical experience, movement of the endotracheal tube during myelography was considered the most likely cause of the damage. This case underscores the importance of monitoring horses for development of respiratory signs after general anaesthesia for computerised tomography and myelography.