Preliminary study evaluating the assessment of changes in pulmonary function associated with body positioning in dogs with suspected aspiration pneumonia.

OBJECTIVE: To evaluate the variability in arterial blood gas (ABG) assessment of pulmonary function with different body positioning in dogs with suspected aspiration pneumonia. KEY FINDINGS: The median differences in alveolar-arterial gradient, Pao2 , and Paco2 values in different recumbencies were not statistically significantly different, both within patients and across the study population. No difference was noted in ABG values in the subgroups with unilateral or bilateral disease or that were more affected on the right side versus the left side. SIGNIFICANCE: This preliminary study provides data that can be used to calculate appropriate sample sizes for subsequent studies investigating the impact of recumbency on pulmonary function in patients with aspiration pneumonia.

Cats undergoing spay with medetomidine, ketamine and butorphanol develop arterial oxygen desaturation independent of surgical positioning and increased intraocular pressure in Trendelenburg position.

INTRODUCTION: This study observed the effects of three different surgical positions on arterial blood oxygenation measured noninvasively by pulse oximetry (SpO2) and on intraocular pressure (IOP) in anaesthetised cats undergoing spay. A total of 222 female feral cats were anaesthetised for a large-scale trap-neuter-return program with an intramuscular combination of medetomidine (0.03 - 0.05 mg/kg), ketamine (7 - 10 mg/kg) and butorphanol (0.4 mg/kg). Cats were randomly allocated to undergo spay in either Trendelenburg (70° downward head tilt), lateral or dorsal recumbency. SpO2 and pulse rate were measured at baseline, prior to surgical positioning, after one minute in surgical position and in one-minute intervals after surgical incision. Intraocular pressure was measured before positioning and at the end of surgery. At the end of surgery, all cats were placed into left lateral recumbency and all parameters were revaluated after five minutes. No significant differences between the three positions were found regarding SpO2, but an increase over time was observed. In total, 52 ± 10% (mean ± SD) of cats were hypoxaemic (SpO2 < 90%) at baseline. SpO2 improved over time, but 27 ± 3% (mean ± SD) of the cats remained hypoxaemic at the end of surgery. Trendelenburg position increased IOP during surgery (mean 31 ± 6 mmHg, individual max. 48 mmHg, versus 17 ± 4 mmHg in dorsal/lateral recumbency) but normalised after 5 mins in lateral recumbence. All cats recovered well from surgery and were released within 24 hours post-anaesthesia. Surgical position was shown to have no notable influence on SpO2 during anaesthesia in cats not receiving oxygen supplementation, whereas Trendelenburg position led to increased IOP. Oxygen supplementation is recommended with this anaesthetic protocol, as hypoxaemia is frequently observed.

INTRODUCTION: Dans cette étude, on a observé les effets de trois positions chirurgicales différentes sur l'oxygénation du sang artériel mesurée de manière non invasive par oxymétrie de pouls (SpO2) et sur la pression intraoculaire (PIO) chez des chattes anesthésiées subissant une stérilisation. Un total de 222 chattes sauvages ont été, dans le cadre d'un large programme de piégeage-castration-libération, anesthésiées avec une combinaison de médétomidine (0,03 à 0,05 mg/kg), de kétamine (7 à 10 mg/kg) et de butorphanol (0,4 mg/kg) par voie intramusculaire. Les chattes ont été réparties au hasard pour subir une stérilisation en Trendelenburg (inclinaison de la tête à 70 ° vers le bas), en décubitus latéral ou dorsal. La SpO2 et la fréquence du pouls ont été mesurées au départ, avant le positionnement chirurgical, après une minute en position chirurgicale et à des intervalles d'une minute après l'incision chirurgicale. La pression intraoculaire a été mesurée avant le positionnement et à la fin de la chirurgie. À la fin de la chirurgie, toutes les chattes ont été placées en décubitus latéral gauche et tous les paramètres ont été réévalués après cinq minutes. Aucune différence significative entre les trois positions n'a été constatée concernant la SpO2, mais une augmentation au fil du temps a été observée. Au total, 52 ± 10% (moyenne ± SD) des chattes étaient hypoxémiques (SpO2.

Evaluation of cranial tibial translation in dogs: Diagnostic accuracy of radiographic method using a simple device.

A hand-made, radiolucent, custom-designed device having a mobile and a non-mobile platforms was used to objectively quantify the in vivo cranial tibial translation, in order to assess the functional status of cranial-cruciate-ligament (CrCL) in dogs. The hypothesis was that changes in CrCL integrity would result in detectable changes in tibial translation. To validate the diagnostic method, data from injured (PA, n = 32), contralateral (CO, n = 32) and healthy stifles (HE, n = 32) were compared. Normalized tibial translation (ΔN) of each stifle was measured in medio-lateral radiographic projection obtained before and during standard thrust force application, in PA (43.59±12.97%), CO (20.32±6.69%) and HE (12.22±3.77%). Comparing PA with HE and CO (ΔN cut-off value: 29.73%), diagnosis could be issued with very high probability. Comparing HE with CO (ΔN cut-off value: 14.80%), high performance was obtained. The translator device could be a useful tool to objectively quantify the in vivo tibial translation in dogs with CrCL rupture, before surgery and during post-operatory follow-up.

The effect of patient positioning on adrenal gland linear measurements estimated from computed tomographic images in healthy beagle dogs.

Considering that recumbency can lead to a change in localization, detectability of distinct margins and thus measurement of the organs and reconstruction quality, it is of value to evaluate the effect of positioning on the objective evaluation of abdominal organs in computed tomography (CT). The objective of the present study was to evaluate the effect of patient decubitus on adrenal gland CT biometry. For this purpose, 6 clinically healthy adult beagle dogs underwent CT examination in 4 recumbencies. The various adrenal gland's size measurements were performed by 2 observers. Statistical analyses revealed that repeatability and reproducibility was the highest on the ventral and right lateral recumbencies, respectively. Significant differences were found in the left adrenal gland's length between the different positions (P < 0.001) and the left adrenal gland's width of the cranial pole measured in the dorsal plane (P < 0.04). The measurements on the parasagittal images differed significantly for the left adrenal length (P = 0.01), cranial pole height (P = 0.03), the right adrenal gland's lateral limb's length (P = 0.05) and medial limb's caudal poles height (P < 0.01). The caudal pole height of the right adrenal gland's medial limb was significantly different (P < 0.01) in all positions on the transverse images. In addition, the adrenal position differed significantly, except for the left adrenal gland relative to the nearest renal vessel (P = 0.1). According to these results, it is recommended to perform a CT of adrenal glands always in the same recumbency. If adrenal glands are evaluated on images taken in various recumbencies, we suggest relying on the measurements made on transverse plane images.

Evaluation of postoperative complication rates in cats undergoing perineal urethrostomy performed in dorsal recumbency.

CASE SERIES SUMMARY: Medical records were reviewed for cats that underwent a perineal urethrostomy performed in dorsal recumbency for the treatment of urethral obstruction. Information, including signalment, reason for presentation, number of previous obstructions, surgery time, and perioperative and postoperative complications, were collected through a review of medical records and owner follow-up. The objective was to evaluate short- and long-term complications in cats that underwent perineal urethrostomy performed in dorsal recumbency for treatment of urethral obstruction. RELEVANCE AND NOVEL INFORMATION: No major or life-threatening complications, such as urethral stricture, re-obstruction, euthanasia due to lower urinary signs or chronic urinary tract infection, were reported. Short-term complications were limited to dysuria in 2/12 (16.7%) cats. Long-term follow-up was available for nine cats. The most common long-term complication seen in this population of cats was a single recurrence of urinary tract infection in 3/9 (33.3%) cats that resolved after a short course of empirical antibiotic therapy. Performing perineal urethrostomy in dorsal recumbency is safe and may have advantages to ventral recumbency due to improved visualization, allowing for more efficient dissection and improved accuracy in tissue apposition during closure. We believe this has been a major contributor to our reported reduced major postoperative complication rate.

Cardiopulmonary changes induced by retroperitoneal insufflation in healthy dogs in sternal recumbency with the abdomen unsupported.

This study assessed the effects of retroperitoneal carbon dioxide (CO2) insufflation on cardiopulmonary variables and intra-abdominal pressure (IAP) in mechanically ventilated dogs in sternal recumbency with the abdomen unsupported, following placement of a positioning kit and towels under the pectoral and pelvic regions. General anesthesia was induced in eight healthy adult male Beagles. A Swan-Ganz catheter was placed in the pulmonary artery via the jugular vein for cardiac output measurements. A Foley urethral catheter was placed to monitor transvesical IAP. A 10 mm balloon blunt-tip trocar was inserted into the retroperitoneal space. With a fixed respiratory rate and tidal volume by mechanical ventilation, insufflation pressure was sequentially increased from 0 to 10 mmHg in 5 mmHg increments, followed by desufflation. All variables were measured before insufflation, 5 min after the establishment of each insufflation pressure, and after desufflation. At 10 mmHg, the IAP was nearly equal to insufflation pressure. Cardiopulmonary function was not compromised at any point, although the cardiac index (CI), heart rate, mean arterial pressure (MAP), and mean pulmonary arterial pressure increased within normal ranges. End-tidal CO2 concentration, arterial CO2 partial pressure, and oxygen delivery index (DO2I) increased, whereas pH decreased, at 10 mmHg. CI, MAP, and DO2I did not recover to baseline after decompression. Thus, retroperitoneal CO2 insufflation up to 10 mmHg is well tolerated by mechanically ventilated dogs positioned in sternal recumbency with the abdomen unsupported, although sympathetic changes may occur with an insufflation pressure increase.

Comparison of various types of inert gas components on efficacy of an alveolar recruitment maneuver in dorsally recumbent anesthetized horses.

OBJECTIVE: To assess effects of nitrogen and helium on efficacy of an alveolar recruitment maneuver (ARM) for improving pulmonary mechanics and oxygen exchange in anesthetized horses. ANIMALS: 6 healthy adult horses. PROCEDURES: Horses were anesthetized twice in a randomized crossover study. Isoflurane-anesthetized horses in dorsal recumbency were ventilated with 30% oxygen and 70% nitrogen (treatment N) or heliox (30% oxygen and 70% helium; treatment H) as carrier gas. After 60 minutes, an ARM was performed. Optimal positive end-expiratory pressure was identified and maintained for 120 minutes. Throughout the experiment, arterial blood pressures, heart rate, peak inspiratory pressure, dynamic compliance (Cdyn), and Pao2 were measured. Variables were compared with baseline values and between treatments by use of an ANOVA. RESULTS: The ARM resulted in significant increases in Pao2 and Cdyn and decreases in the alveolar-arterial gradient in the partial pressure of oxygen in all horses. After the ARM and during the subsequent 120-minute phase, mean values were significantly lower for treatment N than treatment H for Pao2 and Cdyn. Optimal positive end-expiratory pressure was consistently 15 cm H2O for treatment N, but it was 10 cm H2O (4 horses) and 15 cm H2O (2 horses) for treatment H. CONCLUSIONS AND CLINICAL RELEVANCE: An ARM in anesthetized horses might be more efficacious in improving Pao2 and Cdyn when animals breathe helium instead of nitrogen as the inert gas.

The Elekta Fraxion™ system is not suitable for maxillary fixation in canine conformal radiation therapy techniques.

In this prospective, exploratory study, we evaluated the positioning accuracy in a group of 15 dogs undergoing fractionated stereotactic radiotherapy for tumors affecting the head, using a modified human maxillary fixation device (Elekta Fraxion™ system). Positioning was assessed using on-board volumetric imaging, with a six-degrees-of-freedom image registration technique. Prior to treatment delivery, CBCT images were obtained and patient alignment was corrected, in both translational and rotational planes, using a six-degrees-of-freedom robotic patient positioning system (HexaPOD Evo RT System). The maximum angular inter-fraction motions observed were 6.1° (yaw), 10.9° (pitch), and 4.5° (roll). The mean systematic translational errors were 4.7, 2.6, and 2.3 mm, mean random translational errors were 3.0, 2.2, and 2.5 mm, and mean overall translational errors were 2.4, 0.7, and 2.3 mm in the cranial-caudal, lateral, and dorsal-ventral directions, respectively. The mean systematic rotational errors were 1.17°, 0.77°, and 1.43°, the mean rotational random errors were 1.65°, 1.46°, and 1.34° and the mean overall rotational errors were 0.56°, 0.22°, and 0.29° in the yaw, pitch, and roll directions, respectively. The mean error of the three-dimensional vector was 6.9 mm with a standard deviation of 3.8 mm. Ninety-five percent of the three-dimensional vectors were <14.8 mm. This study demonstrates that this maxillary fixation device relies on six-degrees-of-freedom registration and an ability to apply corrections using a six-degrees-of-freedom couch for accurate patient positioning and tumor targeting. Its use in conformal radiation therapy in dogs is not recommended.

Efficacy of an alveolar recruitment maneuver for improving gas exchange and pulmonary mechanics in anesthetized horses ventilated with oxygen or a helium-oxygen mixture.

OBJECTIVE To evaluate efficacy of an alveolar recruitment maneuver (ARM) with positive end-expiratory pressures (PEEPs) in anesthetized horses ventilated with oxygen or heliox (70% helium and 30% oxygen). ANIMALS 6 healthy adult horses. PROCEDURES In a randomized crossover study, horses were anesthetized and positioned in dorsal recumbency. Volume-controlled ventilation was performed with heliox or oxygen (fraction of inspired oxygen [Fio2] > 90%). Sixty minutes after mechanical ventilation commenced, an ARM with PEEP (0 to 30 cm H2O in steps of 5 cm H2O every 5 minutes, followed by incremental steps back to 0 cm H2O) was performed. Peak inspiratory pressure, dynamic lung compliance (Cdyn), and Pao2 were measured during each PEEP. Indices of pulmonary oxygen exchange and alveolar dead space were calculated. Variables were compared with baseline values (PEEP, 0 cm H2O) and between ventilation gases by use of repeated-measures ANOVAs. RESULTS For both ventilation gases, ARM significantly increased pulmonary oxygen exchange indices and Cdyn. Mean ± SD Cdyn (506 ± 35 mL/cm H2O) and Pao2-to-Fio2 ratio (439 ± 36) were significantly higher and alveolar-arterial difference in Pao2 (38 ± 11 mm Hg) was significantly lower for heliox, compared with values for oxygen (357 ± 50 mL/cm H2O, 380 ± 92, and 266 ± 88 mm Hg, respectively). CONCLUSIONS AND CLINICAL RELEVANCE An ARM in isoflurane-anesthetized horses ventilated with heliox significantly improved pulmonary oxygen exchange and respiratory mechanics by decreasing resistive properties of the respiratory system and reducing turbulent gas flow in small airways.

Influence of neck position on commonly performed radiographic measurements of the cervical vertebral region in horses.

OBJECTIVE To determine the influence of various neck positions on cervical vertebral radiographic measurements in horses. ANIMALS 18 client-owned horses examined for lameness but free of cervical disease. PROCEDURES Laterolateral radiographs of the cervical vertebrae from C1 through T1 were acquired for each horse in 3 neck positions (low, neutral, and high). Minimum sagittal diameter, intravertebral sagittal diameter (intra-VSD) ratio, inter-VSD ratio, length of the articular processes joint ratio, vertebral alignment angle, and vertebral fossa angle were measured at each segment in each neck position. Values for the high and low positions were compared with those for the neutral position. RESULTS No significant differences from neutral position values were identified for minimum sagittal diameter, intra-VSD ratio, and vertebral fossa angle as measured in low and high neck positions. Compared with results in the neutral position, the high position resulted in a greater vertebral alignment angle at C3-4 and inter-VSD ratio at C4-5 and a lower length of the articular processes joint ratio at C2-3, C3-4, and C4-5; the low position resulted in a lower vertebral alignment angle at C4-5. However, all observed differences were small. CONCLUSIONS AND CLINICAL RELEVANCE Neck position influenced some radiographic measurements of the cervical vertebrae in horses free of cervical disease. However, because several of these measurements were not or were only minimally affected by neck position, some latitude in neck position may be possible without concern about substantially affecting radiographic measurements in this region.

Cardiorespiratory effects of a 7° reverse Trendelenburg position in anaesthetized horses: a randomized clinical trial.

OBJECTIVE: To evaluate the cardiorespiratory effects of a 7° reverse Trendelenburg position (RTP) in anaesthetized horses. STUDY DESIGN: Randomized, non-blinded clinical trial. ANIMALS: A total of 125 horses undergoing elective surgery in dorsal recumbency. METHODS: Horses were allocated to one of three weight classes and assigned to be positioned either on a horizontal table or on a table in 7° RTP, according to a randomized block design. In all horses, anaesthesia was maintained with isoflurane in oxygen and a constant rate infusion of romifidine. All horses were mechanically ventilated throughout anaesthesia, and routine cardiovascular monitoring and arterial blood gas analysis were performed at 15-minute intervals and relevant variables calculated. Data from the first 60 minutes of anaesthesia were compared between both positions using a mixed model analysis of variance. RESULTS: A significant interaction was found between position and weight class for the alveolar to arterial oxygen tension gradient and F-shunt: these variables were lower in RTP than in horizontal position in the two lowest weight classes and vice versa in the highest weight class. Arterial oxygen tension and oxygenation indices were significantly worse in the horses in the higher weight classes. CONCLUSIONS AND CLINICAL RELEVANCE: A 7° RTP did not result in clinically relevant changes in gas exchange or cardiovascular function. Horses with a higher body weight are at increased risk for hypoxaemia during anaesthesia in dorsal recumbency.

Influence of body position on the measurement of electrocardiographic waves in healthy dogs / Influência do posicionamento corporal na mensuração das ondas eletrocardiográficas em cães sadios

The agreement between the electrocardiographic waves measured from tracings recorded in right lateral recumbency and several other unusual body positions was assessed. Electrocardiograms were recorded in 160 healthy dogs in right lateral, left lateral, dorsal and sternal recumbencies, as well as in standing position. Considering the right lateral recordings as the gold standard, the lowest biases for the majority of ECG parameters were calculated from left lateral recordings, whereas the highest biases were documented from dorsal and standing positions. For the mean electrical axis, the dorsal recumbency produced the lowest bias, while the greatest one was identified in sternal position. An analysis of variance indicated differences when the means of P wave duration and amplitude, duration of QRS and QT, and mean electrical axis obtained in unusual positions were compared with right lateral. In conclusion, left lateral recumbency produced the most similar measurements as compared to right lateral, but the wide limits of agreement preclude the use and interpretation of these positions interchangeably.(AU)

A concordância entre a mensuração das ondas eletrocardiográficas a partir de traçados registrados em cães mantidos em decúbito lateral direito e em vários outros posicionamentos corporais foi avaliada nesta pesquisa. Para tanto, traçados eletrocardiográficos de 160 cães saudáveis foram registrados com os pacientes posicionados nos decúbitos lateral direito, lateral esquerdo, dorsal e esternal, assim como em posição quadrupedal. Tomando como padrão ouro os registros obtidos em decúbito lateral direito, as menores diferenças médias para a maioria dos parâmetros eletrocardiográficos foram obtidas a partir dos traçados registrados com o cão mantido em decúbito lateral esquerdo, enquanto as maiores diferenças médias foram documentadas nos registros obtidos nos decúbitos dorsal e quadrupedal. Para o eixo elétrico médio, o decúbito dorsal produziu a menor diferença média, enquanto a maior foi identificada no registro em posição esternal. A análise de variância mostrou diferenças entre as médias da duração e amplitude da onda P, duração do QRS e do intervalo QT e o eixo elétrico médico quando as posições não usuais foram comparadas com o decúbito lateral direito. Esta pesquisa mostrou que o decúbito lateral esquerdo produziu as medidas mais semelhantes quando comparado àquelas obtidas em decúbito lateral direito. No entanto, os limites de concordância amplos impedem que essas posições sejam utilizadas e interpretadas de maneira intercambiável.(AU)

Effect of intraoperative positioning on the diameter of the vertebral canal in cats during perineal urethrostomy (cadaveric study).

Objectives The objective of this study was to quantify the changes in the diameter of the vertebral canal in the lumbosacral and sacrococcygeal column (L6-Co2) in cats in dorsal and ventral recumbency, simulating real body positioning during a perineal urethrostomy. Methods Twenty-one male feline cadavers were enrolled in the study. All feline cadavers were evaluated by CT. Examinations were performed with the cadaver in a neutral position and dorsal and ventral recumbency. Sagittal vertebral canal diameters (VCDs) were obtained by measuring the distance between the ventral and dorsal aspects of the vertebral canal in the middle of the intervertebral space. Results A comparison of the VCDs between L6 and L7, L7 and S1, S3 and Co1 and Co1 and Co2 in neutral position vs dorsal recumbency revealed a reduction of 0.27 mm (14.6%; P <0.001) between S3 and Co1 and 0.26 mm (18.1%; P <0.001) between Co1 and Co2. No differences were seen when comparing L6-L7 and L7-S1. The VCDs were decreased in all segments when comparing neutral with ventral recumbency. This study revealed a reduction of 0.13 mm between L6 and L7 (3.3%; P = 0.003), 0.14 mm between L7 and S1 (4.1%; P = 0.003), 0.61 mm between S3 and Co1 (32.5%; P <0.001) and 0.63 mm between Co1 and Co2 (44.1%; P <0.001). Comparison of the VCD between dorsal and ventral recumbency in L6-L7, L7-S1, S3-Co1 and Co1-Co2 revealed a decrease in the VCDs in ventral recumbency of 0.13 mm (3.3%; P <0.001), 0.12 mm (3.6%; P <0.001), 0.34 mm (21.0%; P <0.001) and 0.37 mm (31.7%; P <0.001), respectively. Conclusions and relevance The results provide evidence that, from an anatomical point of view, perineal urethrostomy performed in dorsal recumbency is superior to ventral recumbency, but further clinical studies to verify these findings are necessary.

Implementation of immobilization accessories for positioning of small animals for radiation therapy / Implementação de acessórios de imobilização para o posicionamento de pequenos animais para a radioterapia

Radiation therapy is a modality that is presenting great advances in veterinary medicine worldwide. In Brazil, this therapeutic option is underachieved. The success of this method depends on several factors, including the use of appropriate accessories for protection and immobilization of patients. For the immobilization of small animals during treatment, in addition to sedation and anesthesia, immobilizing accessories, similar to those used in human radiotherapy, are used. This study aimed to present proposals for immobilizing accessories adapted to the positioning of small animals in order to be used in radiotherapy planning. In order to achieve results, accessories were made and tested in a living animal simulating a radiotherapy planning, which proved to be favorable to use in positioning small animals undergoing radiotherapy and for implementation processes.(AU)

A radioterapia é uma modalidade que tem apresentando grandes avanços dentro da medicina veterinária pelo mundo. No Brasil, essa opção terapêutica é pouco realizada. O sucesso dessa modalidade depende de vários fatores, entre eles, o uso de acessórios adequados para a proteção e imobilização dos pacientes. Para a imobilização dos pequenos animais durante o tratamento, além da sedação e da anestesia, são utilizados acessórios imobilizadores semelhantes aos usados na radioterapia humana. Devido a isso, este trabalho teve como objetivo de apresentar propostas de acessórios de imobilização adaptados ao posicionamento de pequenos animais para o uso nos planejamentos radioterápicos. Para a sua realização, foram confeccionados acessórios e testados em um animal vivo simulando um planejamento radioterápico, os quais mostraram ser favoráveis ao uso nos posicionamento de pequenos animais submetidos à radioterapia e para sua implementação.(AU)

Influência do posicionamento radiográfico no cálculo interobservador do ângulo do platô tibial em cães / Influence of radiographic positioning in the interobserver measuring of the tibial plateau angle in dogs

O objetivo deste trabalho foi demonstrar que o posicionamento radiográfico inadequado do membro pélvico de cães (imagens obliquadas) afeta a mensuração do ângulo do platô tibial (APT), levando à maior variação entre observadores. Foram realizadas duas projeções radiográficas nos membros pélvicos direito e esquerdo, uma em perfil verdadeiro e a outra com o membro obliquado em 21 cães provenientes do atendimento clínico cirúrgico do Hospital Veterinário da Universidade de Cuiabá, em Cuiabá-MT. Os critérios de inclusão foram cães livres de histórico ou afecção ortopédica nos membros pélvicos, pesando entre 15 e 40 quilos, sem predileção por raça ou sexo, entre dois e sete anos de idade. Foram obtidas 42 imagens radiográficas em perfil verdadeiro e 42 imagens radiográficas obliquadas. Três observadores com experiência em cálculo do APT fizeram as mensurações. Nos cálculos das imagens em perfil verdadeiro, o observador 1 obteve uma média de 23,35º ± 2,82; o observador 2, média de 23,88º ± 4,83; e o observador 3, média de 24,54º ± 4,01, não sendo encontrada diferença significativa entre o cálculo dos três avaliadores, P=0,944 (P > 0,05), nas imagens em perfil verdadeiro. Nos cálculos das imagens obliquadas, o observador 1 obteve uma média de 21,69º ± 4,22; o observador 2, média de 19,42º ± 5,92; e o observador 3, média de 22,64º ± 5,23, e foi encontrada diferença significativa entre o cálculo dos três observadores, P=0,016 (P < 0,05). Com esses dados, pôde-se demonstrar que a imagem radiográfica obliquada compromete o valor final do cálculo do ângulo do platô tibial em cães, levando à variação numérica estatisticamente significativa entre observadores. Conclui-se, assim, que um posicionamento correto do membro pélvico, em perfil verdadeiro, deve ser sempre utilizado para a obtenção de imagens, com o objetivo de mensurar o valor do APT.(AU)

This work aimed at demonstrating that an inadequate radiographic position of pelvic limbs of dogs, from a strict lateral radiographic view, resulted in oblique images, affecting the measurement of the tibial plateau angle (TPA). There were two radiographic projections of the right and the left pelvic limb, one in strict lateral radiographic view and another with inclined hind limb in 21 dogs from the clinical surgical assistance at Hospital Veterinário of Universidade de Cuiabá in Cuiabá-MT. Inclusion criteria were dogs free from pelvic hind limbs orthopedic affection records, weighing between 15 and 40 kilos, without a preference for breed or gender and ageing between two and seven years old. A total of 42 radiographic images in strict lateral radiographic view and 42 inclined limb radiographic views were obtained. Three observers with TPA calculation experience made measurements. In the calculus for the strict lateral radiographic view the first observer has reached an average of 23,35º ± 2,82, the second observer 23,88º ± 4,83 and the third observer 24,54º ± 4,01. No significant statistic differences among the calculus of the three evaluators p=0,944 (P>0,05) was found. In the calculus of the inclined limbs radiographic views the first observer reached an average of 21,69º ± 4,22, the second observer 19,42º ± 5,92 and the third observer 22,64º ±. 5,23. Significant statistic difference in the calculus of the three observers, p=0,016, that is to say, P<0,05 was found. The data indicated that the inclined limb radiographic image compromises the final value of the calculation of tibial plateau angle in dogs. Thus, correct positioning of the pelvic limb, in a strict lateral radiographic view, must be always used for obtaining images aiming at measuring the value of TPA.(AU)

Cardiopulmonary effects of pleural insufflation with CO2 during two-lung ventilation in dorsally recumbent anesthetized horses.

OBJECTIVE: To record the cardiopulmonary effects of pleural CO2 positive pressure insufflation in anesthetized horses. STUDY DESIGN: Prospective study. ANIMALS: Seven horses (mean ± standard deviation, 530.9 ± 68.1 kg) undergoing terminal surgery. METHODS: Horses were sedated with xylazine. Anesthesia was induced with ketamine-propofol and maintained with isoflurane, positive pressure ventilation, detomidine infusion, and butorphanol with the horses in dorsal recumbency. Baseline measurements were cardiac output, heart rate, pulmonary and systemic arterial and right atrial blood pressures, body temperature, expired and inspired gas concentrations, and arterial and mixed venous blood gases, electrolytes, glucose, and lactate concentrations. An 18 gauge 6.6 cm needle was inserted into the right pleural cavity midway between the sternum and dorsal midline in the sixth or seventh intercostal space for pleural pressure (PP) measurement. A 14 gauge 18 cm needle placed 5 cm below the previous needle allowed CO2 insufflation into the pleural cavity. All measurements were repeated after: needle insertion, at 2, 5, and 8 mmHg PPs, and after pleural gas removal (GR). Data were compared with baseline using one-way analysis of variance with repeated measures. p < 0.05 was considered significant. RESULTS: Actual PPs were within 1.1 mmHg of the targeted PP. Pulmonary systolic and mean arterial pressures, alveolar dead space to tidal volume ratio, and isoflurane requirements increased at 8 mmHg PP and GR. Cardiac index decreased at 5 mmHg PP. Stroke index decreased at 2 mmHg PP to GR. PaO2 decreased at 5 mmHg PP to GR. PaCO2 increased at 8 mmHg PP and GR. Oxygen delivery decreased at 5 and 8 mmHg PP. Intrapulmonary shunt fraction and lactate concentration increased with GR. CONCLUSIONS AND CLINICAL RELEVANCE: Severe adverse cardiopulmonary effects arise from CO2 positive pressure insufflation into the right hemithorax in dorsally recumbent isoflurane-anesthetized horses. PP should be ≤2 mmHg.

The effect of anesthetic drug choice on accuracy of high-definition oscillometry in laterally recumbent horses.

OBJECTIVE: To determine the accuracy of high-definition oscillometry (HDO) for arterial pressure measurement during injectable or inhalation anesthesia in horses. STUDY DESIGN: Prospective, clinical study. ANIMALS: Twenty-four horses anesthetized for procedures requiring lateral recumbency. METHODS: Horses were premedicated with xylazine, and anesthesia induced with diazepam-ketamine. Anesthesia was maintained with xylazine-ketamine-guaifenesin combination [TripleDrip (TD; n = 12) or isoflurane (ISO; n = 12)]. HDO was used to obtain systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, and heart rate (HR) using an 8-cm-wide cuff around the proximal tail. Invasive blood pressure (IBP), SAP, MAP, DAP and HR were recorded during HDO cycling. Bland-Altman analysis for repeated measures was used to compare HDO and IBP for all measurements. The generalized additive model was used to determine if means in the differences between HDO and IBP were similar between anesthetic protocols for all measurements. RESULTS: There were >110 paired samples for each variable. There was no effect of anesthetic choice on HDO performance, but more variability was present in TD compared with ISO. Skewed data required log-transformation for statistical comparison. Using raw data and standard Bland-Altman analysis, HDO overestimated SAP (TD, 3.8 ± 28.3 mmHg; ISO, 3.5 ± 13.6 mmHg), MAP (TD, 4.0 ± 23.3 mmHg; ISO, 6.3 ± 10.0 mmHg) and DAP (TD, 4.0 ± 21.2 mmHg; ISO, 7.8 ± 13.6 mmHg). In TD, 26-40% HDO measurements were within 10 mmHg of IBP, compared with 60-74% in ISO. Differences between HDO and IBP for all measurements were similar between anesthetic protocols. The numerical difference between IBP and HDO measurements for SAP, MAP and DAP significantly decreased as cuff width:tail girth ratio increased toward 40%. CONCLUSION AND CLINICAL RELEVANCE: More variability in HDO occurred during TD. The cuff width:tail girth ratio is important for accuracy of HDO.

Review of hypoxaemia in anaesthetized horses: predisposing factors, consequences and management.

OBJECTIVE: To discuss how hypoxaemia might be harmful and why horses are particularly predisposed to developing it, to review the strategies that are used to manage hypoxaemia in anaesthetized horses, and to describe how successful these strategies are and the adverse effects associated with them. DATABASES USED: Google Scholar and PubMed, using the search terms horse, pony, exercise, anaesthesia, hypoxaemia, oxygen, mortality, morbidity and ventilation perfusion mismatch. CONCLUSIONS: Although there is no evidence that hypoxaemia is associated with increased morbidity and mortality in anaesthetized horses, most anaesthetists would agree that it is important to recognise and prevent or treat it. Favourable anatomical and physiological adaptations of a horse for exercise adversely affect gas exchange once the animal is recumbent. Hypoxaemia is recognised more frequently in horses than in other domestic species during general anaesthesia, although its incidence in healthy horses remains unreported. Management of hypoxaemia in anaesthetized horses is challenging and often unsuccessful. Positive pressure ventilation strategies to address alveolar atelectasis in humans have been modified for implementation in recumbent anaesthetized horses, but are often accompanied by unpredictable and unacceptable cardiopulmonary adverse effects, and some strategies are difficult or impossible to achieve in adult horses. Furthermore, anticipated beneficial effects of these techniques are inconsistent. Increasing the inspired fraction of oxygen during anaesthesia is often unsuccessful since much of the impairment in gas exchange is a direct result of shunt. Alternative approaches to the problem involve manipulation of pulmonary blood away from atelectatic regions of the lung to better ventilated areas. However, further work is essential, with particular focus on survival associated with general anaesthesia in horses, before any technique can be accepted into widespread clinical use.