Experimental evaluation of four airway devices in anaesthetized New Zealand White rabbits.

OBJECTIVE: To compare airway management during induction of anaesthesia, spontaneous ventilation (SV) and controlled mechanical ventilation (CMV), using an endotracheal tube (ETT), laryngeal mask (LM), rabbit-specific supraglottic airway device (v-gel) or facemask (FM). STUDY DESIGN: Prospective randomized crossover experiment. ANIMALS: Ten New Zealand White rabbits. METHODS: After premedication, rabbits were randomly allocated to four groups: 1) ETT; 2) LM; 3) v-gel or 4) FM. The required dose of propofol, duration and number of attempts to place an airway device and leakage during SV and CMV at different peak inspiratory pressures (6, 10, 12, 14 and 16 cmH2O) were recorded. Computed tomography (CT) of the head, neck and abdomen were performed before and after CMV. RESULTS: Significantly less propofol and time [2.0±0.5 mg kg-1, 82±34 seconds, p<0.001] were needed to place the FM compared to the three other groups [v-gel 5.1±2.1 mg kg-1, 302±124 seconds; LM 4.8±1.2 mg kg-1, 275±89 seconds; ETT 5.5±1.4 mg kg-1, 315±147 seconds]. A leak > 25% of the tidal volume occurred at the lowest pressure in FM [median (range), 6 (6-8) cmH2O], which was significantly lower than with v-gel [16 (6-no leak at 16) cmH2O], LM [>16 (6-no leak at 16)] or ETT [>16 (no leak at 16) cmH2O] (p<0.001). On CT images, the height and width of the larynx were significantly smaller with v-gel in comparison to FM and LM (p=0.004). A significant increase in the amount of gas in the stomach (p=0.007), but not gastric volume, was detected in FM and LM. CONCLUSIONS AND CLINICAL RELEVANCE: The v-gel is a practical alternative to LM and ETT for airway management and CMV, but can compress the larynx. The FM is easily placed, but significant leakage occurs during CMV.

Clinical evaluation of the v-gel supraglottic airway device in comparison with a classical laryngeal mask and endotracheal intubation in cats during spontaneous and controlled mechanical ventilation.

OBJECTIVE: To compare airway management during induction of anaesthesia, in spontaneous ventilation and controlled mechanical ventilation (CMV), using a cat-specific supraglottic airway device (the v-gel), a classical laryngeal mask (LM) or an endotracheal tube (ETT). STUDY DESIGN: Prospective, randomized clinical trial. ANIMALS: Forty-five healthy cats. METHODS: After premedication, cats were randomly allocated to one of three groups to secure the airway: 1) v-gel; 2) LM; or 3) ETT (cuff pressure: 20 cm H2O). Cats were anaesthetized for elective procedures. The dose of propofol necessary to insert the v-gel, LM or ETT, the number of attempts required to achieve insertion and leakage during spontaneous ventilation and CMV at different peak inspiratory pressures (8, 10, 12, 14 and 16 cm H2O) were recorded. Leakage of >20% of tidal volume was considered as a criterion for exclusion. Significance was set at a p-value of <0.05. RESULTS: Cats in the v-gel group required a median (range) of 3 mg kg(-1) (2-5 mg kg(-1)) of propofol for successful placement, which was significantly less than the 5 mg kg(-1) (3-7 mg kg(-1)) required for endotracheal intubation (p = 0.005). No significant difference in the total dose of propofol was observed between the v-gel and LM [3 mg kg(-1) (2-7 mg kg(-1))] groups or the ETT and LM groups. Significantly more cats in the ETT group were excluded for leakage of >20% during CMV at all pressure settings. CONCLUSIONS AND CLINICAL RELEVANCE: The v-gel is a practical alternative to the LM and ETT for securing the airway after induction of anaesthesia and for CMV up to 16 cm H2O in healthy cats. The v-gel can be inserted at a more superficial level of anaesthesia than the ETT and showed significantly less leakage during CMV than the ETT.

Comparison of the effects of various airway devices on hemodynamic response and QTc interval in rabbits under general anesthesia.

UNLABELLED: In this study, we aimed to compare the effects of various airway devices on QTc interval in rabbits under general anesthesia. The subjects were randomly separated into four groups: Group ETT, Group LMA, Group PLA, Group V-gel. Baseline values and hearth rate, mean arterial pressure and ECG was obtained at the 1st, 5th and 30th minutes after administration of anesthesia and placement of airway device and, QTc interval was evaluated. Difference was observed between ET group and V-gel group in the 5th minute mean arterial pressure values (p < 0.05). It was observed that QTc intervals at the 1st and 5th minute in the ET group significantly increased when compared with the other groups (p < 0.05). Again, it was observed that QTc interval of ET group at the 15th and 30th minute was longer when compared with PLA and V-gel groups (p < 0.05). It was also observed that QTc interval of LMA Group at the 5th minute after intubation significantly increased when compared with V-gel group (p < 0.05). It was observed that HR values of ETT group at the 1st, 5th and 15th minutes after intubation increased with regards to PLA and V-gel groups (p < 0.05). It was determined that the 30th minute hearth rate of ETT group was higher when compared to V-gel group (p < 0.05). CONCLUSION: In our study we observed that V-gel Rabbit affected both hemodynamic response and QT interval less than other airway devices.

Comparison of effects of classic LMA, cobraPLA and V-gel rabbit on QTc interval.

AIM: We aimed to compare the effects of three different supraglottic airway devices, the classic LMA, PLA, and V-gel, on hemodynamics and QTc in rabbits under general anesthesia. METHOD: The rabbits were divided into four groups: Group C (n=5) control group with no airway device used, Group L (n=5, classic LMA), Group P (n=5, CobraPLA) and Group V (n=5, V-gel-rabbit). Basal values of heart rate (HR), mean arterial pressure (MAP) and ECG for QTc interval were measured and the measurements were evaluated at 1, 5, 15, and 30 minutes after inserting the airway device RESULTS: The values of HR, MAP and QTc in Group V at minutes 1 and 5 were significantly different to those in Group L and Group P (p<0.05). DISCUSSION: The classic-LMA and cobraPLA cover a wide part of the perilaryngeal area with cuffs inflated to about 60 cmH2O of pressure resulting in mucosal compression. As V-gel rabbit does not have a cuff, it covers a smaller part of the laryngopharyngeal area, and thus does not cause mucosal compression, and the hemodynamic response is weaker. CONCLUSION: When comparing hemodynamic responses to other supraglottic airway devices, the response to V-gel rabbit is minimal and we consider that similar studies using the I-gel on humans are required (Fig. 5, Ref. 31).

Placement of the feline V-gel Advanced supraglottic airway device and tracheal selectivity during controlled mechanical ventilation: a clinical and tomodensitometric evaluation.

OBJECTIVES: The aims of the study was to assess the placement of the V-gel Advanced (V-gel-A) and to evaluate tracheal selectivity during controlled mechanical ventilation, using CT. METHODS: In this prospective clinical study, 20 healthy cats undergoing general anaesthesia for an elective procedure underwent four successive CT scans from the nose to the mid-abdomen: at baseline (no device); after the placement of the V-gel-A, after a controlled mechanical ventilation (CMV) period of 5 mins; and after the placement of an endotracheal tube (ETT). Using both a purpose designed position score and a gas score estimating the quantity of gas in different digestive regions, the position of the V-gel-A and presence of gas in the digestive tract at each step were evaluated. Number of attempts and times required to place the V-gel-A and ETT were recorded and compared. RESULTS: The V-gel-A was found to be correctly placed, with position scores of 3/5 in six cats, 4/5 in 13 cats and 5/5 in one cat. Imperfect positioning was due to minor axial rotation or incomplete occlusion of the oesophagus by the tip of the device. The gas scores significantly increased after placement of the V-gel-A compared with baseline and after CMV was initiated. Correct positioning of the device was mostly achieved at the first attempt; no significant difference was found in the time required to place V-gel-A vs ETT, nor in the number of attempts (P >0.05). CONCLUSIONS AND RELEVANCE: The V-gel-A was clinically easy to place and use in both spontaneous and controlled ventilation. The device properly fitted the larynx and was never observed to occlude the airway. However, incomplete occlusion of the oesophagus was frequently observed and may lead to a lack of complete tracheal selectivity.

Computational fluid dynamics comparison of the upper airway velocity, pressure, and resistance in cats using an endotracheal tube or a supraglottic airway device.

Intoduction: In veterinary medicine, airway management of cats under general anesthesia is performed with an endotracheal tube (ETT) or supraglottic airway device (SGAD). This study aims to describe the use of computational fluid dynamics (CFD) to assess the velocities, pressures, and resistances of cats with ETT or SGAD. Methods: A geometrical reconstruction model of the device, trachea, and lobar bronchi was carried out from computed tomography (CT) scans that include the head, neck, and thorax. Twenty CT scans of cats under general anesthesia using ETT (n = 10) and SGAD (n = 10) were modeled and analyzed. An inspiratory flow of 2.4 L/min was imposed in each model and velocity (m/s), general and regional pressures (cmH2O) were computed. General resistance (cmH2O/L/min) was calculated using differential pressure differences between the device inlet and lobar bronchi. Additionally, regional resistances were calculated at the device's connection with the breathing circuit (region A), at the glottis area for the SGAD, and the area of the ETT exit (bevel) (region B) and the device itself (region C). Results: Recirculatory flow and high velocities were found at the ETT's bevel and at the glottis level in the SGAD group. The pressure gradient (Δp) was more enhanced in the ETT cases compared with the SGAD cases, where the pressure change was drastic. In region A, the Δp was higher in the ETT group, while in regions B and C, it was higher in the SGAD group. The general resistance was not statistically significant between groups (p = 0.48). Higher resistances were found at the region A (p = <0.001) in the ETT group. In contrast, the resistance was higher in the SGAD cases at the region B (p = 0.001). Discussion: Overall, the provided CT-based CFD analysis demonstrated regional changes in airway pressure and resistance between ETT and SGAD during anesthetic flow conditions. Correct selection of the airway device size is recommended to avoid upper airway obstruction or changes in flow parameters.

Success of placement and complications during v-gel placement and maintenance of anaesthesia.

OBJECTIVES: Airway management during anaesthesia in cats is always a demanding task and is associated with several complications. The aim of this study was to evaluate the practicability and complications during feline-specific laryngeal mask placement in anaesthetised cats as an alternative to endotracheal intubation. METHODS: In this prospective clinical study, laryngeal masks were placed in 148 anaesthetised cats. Success of placement was evaluated by capnography. RESULTS: Placement was possible at the first attempt in 136 cats, at the second attempt in eight cats and at the third attempt in one cat. In one cat, placement was not possible. Two cats were excluded. Failure to position the laryngeal mask at the first attempt was not different between laryngeal mask sizes (P = 0.313) or positioning during placement (P = 0.406). In nine cats, the laryngeal mask dislocated during the procedure. Dislocation occurred more often in the dorsal position than in the sternal (P = 0.018) and right lateral positions (P = 0.046). Mucous obstruction of the laryngeal mask occurred in one of these cats and regurgitation in another. Material-related issues, such as disconnection of the parts of the laryngeal mask and leakage of the balloon, were observed in 2/8 laryngeal masks. CONCLUSIONS AND RELEVANCE: The placement of a feline-specific laryngeal mask was easy to perform. In about 7% of the cases, replacement of the device was required due to mispositioning or dislocation. Full monitoring, including capnography, should be provided to uncover dislocation and airway obstruction immediately.

Evaluation of Alternative Power Sources for Operating CDC Mosquito Surveillance Traps.

Several portable, rechargeable lithium-ion (Li-Ion) cell phone power banks were compared with standard 6-V gel lead-acid batteries as alternative power sources for operating mosquito surveillance equipment. In laboratory trials, ToughTested® (TT)16000 and 24000, Goal Zero Venture™ 70, and Griffin Survivor® units either met or exceeded that of sealed 6-V batteries when operating the Centers for Disease Control and Prevention (CDC) suction light traps (with incandescent light on) for an average of 24 h. No significant difference was found when continually operating traps powered by either the TT16000 or Goal Zero Venture 70 units compared with 6-V batteries (at approximately 57 h). The TT24000 unit was the only Li-Ion power bank that exceeded this threshold at an average of approximately 73 h. In field studies, there was no significant difference in species diversity or abundance of mosquitoes among the above 4 power sources when operating CDC light traps for 24 h compared with 6-V batteries. Our results indicate that portable Li-Ion cell phone power banks ≥10,050 mAh may be suitable replacements for 6-V gel lead-acid batteries when operating these light traps, especially if weight and size constraints influence the extent of mosquito surveillance during deployments.

Comparison of endoscopic endotracheal intubation and the v-gel supraglottic airway device for spontaneously ventilating New Zealand white rabbits undergoing ovariohysterectomy.

BACKGROUND: Due to the technical difficulties with endotracheal intubation of rabbits, a prospective, randomised, controlled study was performed to compare a rabbit-specific supraglottic airway device (SGAD), the v-gel, with endoscopic endotracheal intubation (EEI) in spontaneously breathing rabbits undergoing ovariohysterectomy. METHODS: Fourteen adult female New Zealand white rabbits were randomly allocated to one of two groups based on the method of airway establishment: EEI or v-gel SGAD. Anaesthesia was induced with ketamine and xylazine and maintained using isoflurane in 100 per cent oxygen. Comparisons were made between groups based on placement time of endotracheal tube/SGAD, number of attempts and adjustments, the necessity to increase isoflurane concentrations to maintain a surgical plane of anaesthesia, arterial blood gas values, gross laryngeal evaluation, and laryngotracheal histopathology. RESULTS: Both techniques resulted in elevated arterial pCO2 levels, but the v-gel was associated with more elevated pCO2 in comparison with EEI (P=0.045). Airway trauma was histologically present but clinically negligible in both groups, with no statistically significant differences observed between techniques (P>0.05). Placement time of the v-gel was significantly faster (P=0.003) and required less technical skill than EEI, but was more easily displaced when changing the animal's position (P=0.004). CONCLUSION: The v-gel is a practical alternative to EEI for securing the airway of healthy spontaneously ventilating rabbits, provided a capnograph is utilised to ensure continuous placement. Both airway techniques appear safe and effective with few complications, as long as intermittent positive pressure ventilation can be employed to correct hypercapnia.

Anaesthetic and Perioperative Management of 14 Male New Zealand White Rabbits for Calvarial Bone Surgery.

Calvarial bone surgery on rabbits is frequently performed. This report aims to document a simple and practical anaesthetic and perioperative management for this procedure. Fourteen male New Zealand white rabbits were included in the study. Subcutaneous (SC) dexmedetomidine, ketamine and buprenorphine ± isoflurane vaporized in oxygen administered through a supraglottic airway device (V-gel®) provided clinically suitable anaesthesia. Supplemental oxygen was administered throughout recovery. Monitoring was clinical and instrumental (pulse-oximetry, capnography, invasive blood pressure, temperature, arterial blood gas analysis). Lidocaine was infiltrated at the surgical site and meloxicam was injected subcutaneously as perioperative analgesia. After surgery, pain was assessed five times daily (composite behavioural pain scale and grimace scale). Postoperative analgesia included SC meloxicam once daily for four days and buprenorphine every 8 h for three days (unless both pain scores were at the lowest possible levels). Rescue analgesia (buprenorphine) was administered in case of the score > 3/8 in the composite pain scale, >4/10 on the grimace scale or if determined necessary by the caregivers. Airway management with a V-gel® was possible but resulted in respiratory obstruction during the surgery in two cases. Hypoventilation was observed in all rabbits. All rabbits experienced pain after the procedure. Monitoring, pain assessments and administration of postoperative analgesia were recommended for 48 h.

Assessment of v-gel supraglottic airway device placement in cats performed by inexperienced veterinary students.

Endotracheal intubation has been associated with several complications in cats. The v-gel supraglottic airway device (SGAD) has been developed to adapt to the unique oropharynx of the cat and to overcome these complications. Thirty-three cats were randomly assigned to receive an endotracheal tube (ETT group) or a v-gel SGAD (v-gel group) after induction of general anaesthesia. Third year veterinary students without previous clinical experience placed these devices under direct supervision of an anaesthesiologist. Amount of propofol, number of attempts, time required to secure the airway, leakage around the device, signs of upper airway discomfort and food consumption were compared between the two groups. The v-gel group required less propofol (P=0.03), less time (P<0.01) and fewer attempts (P<0.01) to secure the cats' airway. The incidence of leakage was lower for the v-gel group immediately after placement of the device (P<0.01) and 60 minutes after induction of general anaesthesia (P=0.04). Cats that received the v-gel SGAD presented a lower incidence of upper airway discomfort immediately after the device was removed (P=0.03) and recorded a higher food consumption score (P=0.03). The v-gel SGAD is a feasible way to secure the airway of healthy cats when performed by inexperienced personnel.