Comparison between mainstream (Capnostat 5) and a low-flow sidestream capnometer (Capnostream) in mechanically ventilated, sevoflurane-anesthetized rabbits using a Bain coaxial delivery system.

OBJECTIVE: To evaluate agreement between end-tidal carbon dioxide (Pe'CO2) and PaCO2 with sidestream and mainstream capnometers in mechanically ventilated anesthetized rabbits, with two ventilatory strategies. STUDY DESIGN: Prospective experimental study. ANIMALS: A total of 10 New Zealand White rabbits weighing 3.6 ± 0.3 kg (mean ± standard deviation). METHODS: Rabbits anesthetized with sevoflurane were intubated with an uncuffed endotracheal tube (3.0 mm internal diameter) and adequate seal. For Pe'CO2, the sidestream capnometer sampling adapter or the mainstream capnometer was placed between the endotracheal tube and Bain breathing system (1.5 L minute-1 oxygen). PaCO2 was obtained from arterial blood collected every 5 minutes. A time-cycled ventilator delivered an inspiratory time of 1 second and 12 or 20 breaths minute-1. Peak inspiratory pressure was initially set to achieve Pe'CO2 normocapnia of 35-45 mmHg (4.6-6.0 kPa). A total of five paired Pe'CO2 and PaCO2 measurements were obtained with each ventilation mode for each capnometer. Anesthetic episodes were separated by 7 days. Agreement was assessed using Bland-Altman analysis and linear mixed models; p < 0.05. RESULTS: There were 90 and 83 pairs for the mainstream and sidestream capnometers, respectively. The mainstream capnometer underestimated PaCO2 by 12.6 ± 2.9 mmHg (proportional bias 0.44 ± 0.06 mmHg per 1 mmHg PaCO2 increase). With the sidestream capnometer, ventilation mode had a significant effect on Pe'CO2. At 12 breaths minute-1, Pe'CO2 underestimated PaCO2 by 23.9 ± 8.2 mmHg (proportional bias: 0.81 ± 0.18 mmHg per 1 mmHg PaCO2 increase). At 20 breaths minute-1, Pe'CO2 underestimated PaCO2 by 38.8 ± 5.0 mmHg (proportional bias 1.13 ± 0.10 mmHg per 1 mmHg PaCO2 increase). CONCLUSIONS AND CLINICAL RELEVANCE: Both capnometers underestimated PaCO2. The sidestream capnometer underestimated PaCO2 more than the mainstream capnometer, and was affected by ventilation mode.

Agreement of caudal aortic arterial blood pressure with oscillometry using two cuff widths placed on the thoracic or pelvic limbs of sevoflurane-anesthetized rabbits.

OBJECTIVE: To evaluate agreement with central systemic arterial pressure of an oscillometer and two cuff widths placed on the thoracic or pelvic limbs. STUDY DESIGN: Prospective experimental study. ANIMALS: A group of nine New Zealand White rabbits weighing 3.5 ± 0.3 kg. METHODS: Rabbits were sedated with dexmedetomidine and midazolam, then anesthetized with ketamine and sevoflurane. The femoral artery was surgically exposed and a 20 gauge, 5 cm catheter inserted to measure systolic (SAP), mean (MAP) and diastolic (DAP) blood pressure at the iliac artery and caudal aorta junction. Adjustments of vaporizer dial and dobutamine infusion provided a range of invasive blood pressure (IBP). Two measurements of IBP were recorded during the oscillometer cycling phase, and the mean value was used in analyses. Oscillometer cuffs of bladder width 2.0 cm (S1) and 2.5 cm (S2) were placed proximal to the carpus and tarsus. Cuff width to circumference ratio was calculated. Oscillometer SAP, MAP and DAP were paired with corresponding IBP values. Agreement was assessed using linear mixed models (p < 0.05). RESULTS: Cuff ratios for both limbs were 41% (S1 cuff) and 50% (S2 cuff) and 122-139 paired observations were obtained. There was significant limb × cuff interaction with SAP and MAP. The oscillometer overestimated SAP and MAP on the pelvic limb and underestimated SAP and MAP on the thoracic limb. For SAP, the oscillometer overestimated by constant bias (-19 ± 2 mmHg) and proportional bias (0.28 ± 0.02 mmHg per 1 mmHg increase). For MAP, the oscillometer underestimated by constant bias (4 ± 2 mmHg) and was worse with S2 on the thoracic limb. Overestimation was similar between cuffs on the pelvic limb. For DAP, the oscillometer underestimated by constant bias (15 ± 2 mmHg). CONCLUSIONS AND CLINICAL RELEVANCE: Cuff S1 on the thoracic limb provided best estimation of MAP.

The use of veterinary point-of-care ultrasound by veterinarians: A nationwide Canadian survey.

This survey assessed how veterinary point-of-care ultrasound (VPOCUS), including abdominal and thoracic focused assessment with sonography for trauma (AFAST, TFAST), is used across Canada. Seventy-four veterinarians completed an online survey; 88% (65/74) used ultrasound, 94% (61/65) performed AFAST, and 69% (45/65) performed TFAST. Reasons for not performing VPOCUS included no machine/poor quality machine, lack of experience/confidence, and lack of training/education. Abdominal effusion, and pleural and pericardial effusion were the most frequently diagnosed AFAST and TFAST pathologies, respectively. Lung and cardiovascular ultrasound examinations were infrequently performed. Subpleural consolidation was rarely included in VPOCUS. Most respondents performed VPOCUS, with AFAST being more frequently and confidently preformed than TFAST. More training, education, and standardization of techniques appear to be key elements to help build confidence and experience, particularly with regard to TFAST applications and diagnosis.

Utilisation de l'échographie au lieu d'intervention par les vétérinaires : une enquête pancanadienne. Cette enquête visait à évaluer comment l'échographie au lieu d'intervention vétérinaire (VPOCUS), incluant l'évaluation abdominale et thoracique avec l'échographe pour un trauma (AFAST, TFAST), est utilisée à travers le Canada. Soixante-quatorze vétérinaires ont complété une enquête en ligne; 88 % (65/74) utilisait l'échographie, 94 % (61/65) effectuaient AFAST et 69 % (45/65) effectuaient TFAST. Les raisons invoquées pour ne pas effectuer VPOCUS incluaient aucun appareil/équipement de pauvre qualité, manque d'expérience/confiance et manque de pratique/formation. Les effusions abdominales de même que les effusions pleurales et péricardiques étaient les pathologies AFAST et TFAST les plus fréquemment diagnostiquées, respectivement. Les examens échographiques pulmonaires et cardiovasculaires étaient effectués peu fréquemment. La consolidation sub-pleurale était rarement incluse dans les VPOCUS. La plupart des répondants réalisaient VPOCUS, avec AFAST effectué plus fréquemment et avec plus de confiance que TFAST. Plus de pratique, de formation et de standardisation des techniques semblent des éléments clés pour aider à bâtir la confiance et l'expérience, particulièrement en ce qui concerne les applications et le diagnostic des TFAST.(Traduit par Dr Serge Messier).