Computed Tomography Assessment of Tidal Lung Overinflation in Domestic Cats Undergoing Pressure-Controlled Mechanical Ventilation During General Anesthesia.

Objective: This study aimed to evaluate lung overinflation at different airway inspiratory pressure levels using computed tomography in cats undergoing general anesthesia. Study Design: Prospective laboratory study. Animals: A group of 17 healthy male cats, aged 1.9-4.5 years and weighing 3.5 ± 0.5 kg. Methods: Seventeen adult male cats were ventilated in pressure-controlled mode with airway pressure stepwise increased from 5 to 15 cmH2O in 2 cmH2O steps every 5 min and then stepwise decreased. The respiratory rate was set at 15 movements per min and end-expiratory pressure at zero (ZEEP). After 5 min in each inspiratory pressure step, a 4 s inspiratory pause was performed to obtain a thoracic juxta-diaphragmatic single slice helical CT image and to collect respiratory mechanics data and an arterial blood sample. Lung parenchyma aeration was defined as overinflated, normally-aerated, poorly-aerated, and non-aerated according to the CT attenuation number (-1,000 to -900 HU, -900 to -500 HU, -500 to -100 HU, and -100 to +100 HU, respectively). Result: At 5 cmH2O airway pressure, tidal volume was 6.7± 2.2 ml kg-1, 2.1% (0.3-6.3%) of the pulmonary parenchyma was overinflated and 84.9% (77.6%-87.6%) was normally inflated. Increases in airway pressure were associated with progressive distention of the lung parenchyma. At 15 cmH2O airway pressure, tidal volume increased to 31.5± 9.9 ml kg-1 (p < 0.001), overinflated pulmonary parenchyma increased to 28.4% (21.2-30.6%) (p < 0.001), while normally inflated parenchyma decreased 57.9% (53.4-62.8%) (p < 0.001). Tidal volume and overinflated lung fraction returned to baseline when airway pressure was decreased. A progressive decrease was observed in arterial carbon dioxide partial pressure (PaCO2) and end-tidal carbon dioxide (ETCO2) when the airway pressures were increased above 9 cmH2O (p < 0.001). The increase in airway pressure promoted an elevation in pH (p < 0.001). Conclusions and Clinical Relevance: Ventilation with 5 and 7 cmH2O of airway pressure prevents overinflation in healthy cats with highly compliant chest walls, despite presenting acidemia by respiratory acidosis. This fact can be controlled by increasing or decreasing respiratory rate and inspiratory time.

Tomography, Radiography, and Rhinoscopy in Diagnosis of Benign and Malignant Lesions Affecting the Nasal Cavity and Paranasal Sinuses in Dogs: Comparative Study.

Canine nasal and paranasal diseases have variable causes. Presumptive diagnosis is based on clinical manifestations; however, high similarity of clinical signs often calls for diagnostic imaging modalities and rhinoscopy before a definitive diagnosis can be reached. This study sets out to determine the value of rhinoscopy, radiography, and computed tomography (CT) of the head for canine nasal and paranasal disease diagnosis using a purposely developed comparative score. In all, 20 dogs presenting with clinical signs consistent with nasal disease were used. Patients were submitted to radiographic, CT, and rhinoscopic assessment; rhinoscopy-guided biopsy collection was performed in cases presenting with tissue proliferation, ulceration, or other nasal mucosal lesions. Rhinoscopy and rhinoscopy combined with CT significantly contributed to nasal disease diagnosis. Rhinoscopy and CT are complementary diagnostic modalities. Rhinoscopy proved helpful for confirmation of presumptive diagnosis and allowed image-assisted biopsy collection whereas CT contributed to effective determination of lesion extension and involvement of adjacent structures. Yet, histologic confirmation remains vital for definitive diagnosis.

Tomografia computadorizada de mastocitomas em cães: avaliação pré e pós-tratamento quimioterápico / Computed tomography of mast cell tumors in dogs: assessment before and after chemotherapy

Foram avaliados, por meio da tomografia computadorizada, 19 cães com mastocitomas tratados com quimioterapia. Aspectos como contorno, atenuação, realce pós-contraste e presença de clivagem com estruturas adjacentes foram avaliados. Aplicaram-se os critérios RECIST e a mensuração volumétrica das lesões para se avaliar a resposta ao tratamento. Quanto à atenuação, os mastocitomas se mostraram como lesões homogêneas ou heterogêneas, com tendência a limites definidos e contornos regulares e apresentaram realce moderado após administração do contraste iodado intravenoso. Os métodos RECIST e a mensuração volumétrica apresentaram uma excelente concordância na classificação da resposta terapêutica, fornecendo um bom parâmetro da resposta ao tratamento instituído. O exame de tomografia computadorizada se mostrou útil na delimitação do tumor e importante ferramenta no planejamento das margens cirúrgicas.

Nineteen dogs with mast cell tumors treated with chemotherapy were evaluated by computed tomography (CT). Were evaluated aspects related to contours, attenuation, post-contrast enhancement and presence of cleavage with adjacent structures. The RECIST criteria and volumetric measurement of lesions were performed to assess the response to treatment. The mast cell tumors presented a homogeneous or heterogeneous attenuation, presented more frequently a well delineated and regular contours and moderate enhancement after intravenous administration of the iodinated contrast media. The methods RECIST and volumetric measurements showed an excellent agreement to the classification of therapeutic response, providing a good parameter of the response to treatment. The CT examination proved to be useful in the delimitation of the tumor and an important tool for planning of surgical margins.

Revisão anatômica do seio venoso sagital dorsal no crânio de cães braquicéfalos / Anatomic features of the dorsal venous sinus in skull of brachycephalous dogs

Os seios venosos do crânio realizam a drenagem do cérebro e da medula espinhal, a fim de manter a homeostasia e o perfeito funcionamento do sistema nervoso central. Lesões na rede venosa cerebral podem causar déficits severos tais como hemiplegia, hemorragia, coma e morte. Os seios venosos são importantes pontos de referência para a realização de técnicas cirúrgicas de acesso ao cérebro. Este estudo visou analisar o trajeto do seio venoso sagital dorsal no crânio de cães braquicéfalos. Os animais braquicéfalos possuem crânios curtos e com características biométricas específicas. Foram utilizados 8 crânios de cães da raça Boxer, que foram submetidos à injeção de látex com pigmento corado e sulfato de bário. Após a perfusão, foram feitas radiografias contrastadas e imagens de tomografia computadorizada para relacionar o seio venoso com a estrutura óssea e dimensões relativas da calota craniana. Os crânios apresentaram índice cefálico (IC) médio de 91,24±8,34mm e índice crânio-facial (ICF) médio de 2,89±0,23mm. As mensurações do seio venoso sagital dorsal, relativas à calota craniana, apresentaram os seguintes valores médios: Area = 10,18±4,69mm²; D1 = 11,84±2,35mm; D2 = 19,57±2,61mm; D3 = 17,88±2,31mm; D4 = 25,32±5,68mm; e D5= 24,84±4,40mm.

The dorsal venous sinuses of the Dura mater perform the cerebral and spinal cord drainage to keep homeostasis of the Central Nervous System. Injuries in the cerebral venous network may cause severe deficits, including hemiplegia, hemorrhage, coma and death. The main landmark for neurologic surgery is the Dura mater venous sinus. The aim of this study is to analyse the pathway of the Sinus sagittalis dorsalis in the brachycephalous skull, as the brachycephalous dogs have specific characteristics. The skulls were taken from 8 Boxer dogs and venous perfusion with latex and barium sulfate solution was performed. After the perfusion, radiographies and tomographies were obtained to relate the dorsal sagittal sinus and the skull averages. The cephalic index showed mean values of 91.24±8.34cm, and the cranio-facial index was 2.89±0.23cm. The venous sinus mensuration interface to the skull was: Area = 10.18±4.69mm²; D1 = 11.84±2.35mm; D2 = 19.57±2.61mm; D3 = 17.88±2.31mm; D4 = 25.32±5.68mm e D5 = 24.84±4.40mm.