Effects of cuff size and position on the agreement between arterial blood pressure measured by Doppler ultrasound and through a dorsal pedal artery catheter in anesthetized cats.

OBJECTIVE: To compare the effects of cuff size/position on the agreement between arterial blood pressure measured by Doppler ultrasound (ABPDoppler) and dorsal pedal artery catheter measurements of systolic (SAPinvasive) and mean arterial pressure (MAPinvasive) in anesthetized cats. STUDY DESIGN: Prospective study. ANIMALS: A total of eight cats (3.0-3.8 kg) for neutering. METHODS: During isoflurane anesthesia, before surgery, changes in end-tidal isoflurane concentrations and/or administration of dopamine were performed to achieve SAPinvasive within 60-150 mmHg. Cuff sizes 1, 2 and 3 (bladder width: 20, 25 and 35 mm, respectively) were placed on distal third of the antebrachium, above the tarsus and below the tarsus for ABPDoppler measurements. Agreement between ABPDoppler and SAPinvasive or between ABPDoppler and MAPinvasive was compared with reference standards for noninvasive blood pressure devices used in humans and small animals. RESULTS: Mean bias and precision (±standard deviation) between ABPDoppler and SAPinvasive met veterinary standards (≤10 ± 15 mmHg), but not human standards (≤5 ± 8 mmHg), with cuffs 1 and 2 placed on the thoracic limb (7.4 ± 13.9 and -5.8 ± 9.5 mmHg, respectively), and with cuff 2 placed proximal to the tarsus (7.2 ± 12.4 mmHg). Cuff width-to-limb circumference ratios resulting in acceptable agreement between ABPDoppler and SAPinvasive were 0.31 ± 0.04 (cuff 1) and 0.42 ± 0.05 (cuff 2) on the thoracic limb, and 0.43 ± 0.05 (cuff 2) above the tarsus. ABPDoppler showed no acceptable agreement with MAPinvasive by any reference standard. CONCLUSIONS AND CLINICAL RELEVANCE: The agreement between ABPDoppler and SAPinvasive can be optimized by placing the occlusive cuff on the distal third of the antebrachium and above the tarsus. In these locations, cuff width should approach 40% of limb circumference to provide clinically acceptable estimations of SAPinvasive. Doppler ultrasound cannot be used to estimate MAPinvasive in cats.

Age-related changes of the cerebral ventricles of healthy domestic cats / Alterações senis dos ventrículos cerebrais de gatos domésticos hígidos

This study aimed to determine age-related changes of the cerebral ventricles of healthy non-brachycephalic domestic cats by the acquisition of brain MRI images of 12 adult (1 to 6 years), 11 mature (7 to11 years) and 10 geriatric (12 years or more) cats. Our hypothesis is that the cerebral ventricular system of cats expands with increasing age. The possibility of the evidence of the olfactory bulb cavities and temporal horns of the lateral ventricles were evaluated in this study. Volumes of the olfactory bulb cavities, lateral ventricles (including the temporal horns), third ventricle, mesencephalic aqueduct and fourth ventricle were measured and corrected for the intracranial volume. Significant differences were found between the adult and mature groups in relation to the geriatric one for the variable related to the evidence of the temporal ventricular horns, which were most frequently visualized in geriatric cats. Percentage of the right lateral and third ventricles volume by intracranial volume were significantly higher in geriatric cats compared to the adults. The results of this study demonstrate that ventricular dilation tends to occur with advancing age in cats, as well as the increase in the frequency of the temporal ventricular horn evidence, as had been indicated in the hypothesis of the study.(AU)

O estudo objetivou a determinação das alterações senis dos ventrículos cerebrais de gatos domésticos hígidos não braquicefálicos pela aquisição de imagens encefálicas de 12 indivíduos adultos (1 a 6 anos), 11 maduros (7 a 11 anos) e 10 geriátricos (12 anos de idade ou mais) por ressonância magnética. Nossa hipótese é de que o sistema ventricular dos gatos se expande com o avanço da idade. A possibilidade de evidenciação das cavidades do bulbo olfatório e dos cornos temporais dos ventrículos laterais foi avaliada nesse estudo. Os volumes das cavidades do bulbo olfatório, ventrículos laterais (incluindo os cornos temporais), terceiro ventrículo, aqueduto mesencefálico e quarto ventrículo foram mensurados e corrigidos de acordo com o volume intracraniano. Diferenças significativas foram encontradas entre os grupos dos adultos e maduros em relação aos geriátricos para a variável referente à evidenciação dos cornos temporais, que foram visualizados de forma mais frequente nos gatos geriátricos. A porcentagem do volume do ventrículo lateral direito e do terceiro ventrículo em relação ao volume intracraniano foi significativamente maior nos animais geriátricos em comparação aos adultos. Os resultados desse estudo demonstram que a dilatação ventricular tende a ocorrer com o avanço da idade nos gatos, assim como o aumento na frequência da evidenciação dos cornos temporais, como havia sido indicado na hipótese do estudo.(AU)

Brain parenchymal changes during normal aging in domestic cats / Alterações do parênquima cerebral durante a senilidade em gatos domésticos

This study aimed to identify changes related to brain parenchyma as advancing age in healthy domestic cats. Our hypothesis is that cats suffer cerebral and cerebellar atrophy and show focal changes in signal intensity of the brain parenchyma in accordance with the progression of age. Twelve adult (1 to 6 years), eleven mature (7 to11 years) and ten geriatric non-brachycephalic cats (12 years or more of age) underwent brain magnetic resonance imaging (MRI). There were no changes in signal intensity and contrast uptake in brain parenchyma of the cats. Geriatric animals showed significantly lower average thickness of the interthalamic adhesion and percentage of the cerebral parenchyma volume in relation to intracranial volume than those found in the adult group. No significant differences were found between groups for cerebral volume, cerebellar volume and percentage of cerebellar volume in relation to intracranial volume. The results of this study indicate that atrophy of the cerebral parenchyma, including the interthalamic adhesion, occurs with age in domestic cats, confirming the hypothesis of the study. However, the results did not corroborate the hypothesis that cats show cerebellar atrophy and focal changes in signal intensity of the brain parenchyma with advancing age.(AU)

Este estudo objetivou a identificação de alterações no parênquima cerebral relacionadas ao avanço da idade em gatos domésticos saudáveis. Nossa hipótese é de que os gatos sofrem atrofia cerebral e cerebelar, além de alterações focais na intensidade do sinal do parênquima cerebral, de acordo com a progressão da idade. Doze gatos não braquicéfalos adultos (1 a 6 anos), onze maduros (7 a 11 anos) e dez geriátricos (12 anos ou mais) foram submetidos à ressonância magnética encefálica. Não foram observadas alterações na intensidade do sinal e na captação de contraste do parênquima encefálico nos gatos. Os animais geriátricos apresentaram médias da espessura da adesão intertalâmica e porcentagem do volume do parênquima cerebral, em relação ao volume intracraniano, significativamente menores a aquelas encontradas no grupo dos adultos. Não foram encontradas diferenças significativas entre os grupos para volume cerebral, volume cerebelar e porcentagem de volume cerebelar em relação ao volume intracraniano. Os resultados deste estudo indicam que a atrofia do parênquima cerebral, incluindo a adesão intertalâmica, ocorre com o avanço da idade em gatos domésticos, confirmando a hipótese do estudo. No entanto, os resultados não corroboraram a hipótese de que os gatos apresentam atrofia cerebelar e alterações focais na intensidade do sinal do parênquima encefálico com a progressão da idade.(AU)

Changes in pulse pressure variation and plethysmographic variability index caused by hypotension-inducing hemorrhage followed by volume replacement in isoflurane-anesthetized dogs.

OBJECTIVE: To compare changes in pulse pressure variation (PPV) and plethysmographic variability index (PVI) induced by hemorrhage followed by volume replacement (VR) in isoflurane-anesthetized dogs. ANIMALS: 7 healthy adult dogs. PROCEDURE: Each dog was anesthetized with isoflurane and mechanically ventilated. End-tidal isoflurane concentration was adjusted to maintain mean arterial pressure (MAP) at 60 to 70 mm Hg before hemorrhage. Controlled hemorrhage was initiated and continued until the MAP decreased to 40 to 50 mm Hg, then autologous blood removed during hemorrhage was retransfused during VR. Various physiologic variables including PPV and PVI were recorded immediately before (baseline) and after controlled hemorrhage and immediately after VR. RESULTS: Mean ± SD PPV and PVI were significantly increased from baseline after hemorrhage (PPV, 20 ± 6%; PVI, 18 ± 4%). After VR, the mean PPV (7 ± 3%) returned to a value similar to baseline, whereas the mean PVI (10 ± 3%) was significantly lower than that at baseline. Cardiac index (CI) and stroke index (SI) were significantly decreased from baseline after hemorrhage (CI, 2.07 ± 0.26 L/min/m(2); SI, 20 ± 3 mL/beat/m(2)) and returned to values similar to baseline after VR (CI, 4.25 ± 0.63 L/min/m(2); SI, 36 ± 6 mL/beat/m(2)). There was a significant positive correlation (r(2) = 0.77) between PPV and PVI after hemorrhage. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that both PPV and PVI may be useful for identification of dogs that respond to VR with increases in SI and CI (ie, dogs in the preload-dependent limb of the Frank-Starling curve).

Effects of dexmedetomidine on pulse pressure variation changes induced by hemorrhage followed by volume replacement in isoflurane-anesthetized dogs.

OBJECTIVES: To evaluate the effects of dexmedetomidine (DEX) on changes in pulse pressure variation (PPV) induced by hemorrhage followed by volume replacement (VR) during isoflurane (ISO) anesthesia. DESIGN: Prospective, randomized, crossover study. SETTING: Research laboratory at a veterinary teaching hospital. ANIMALS: Eight adult dogs. INTERVENTIONS: Anesthesia was maintained with 1.3 times the minimum alveolar concentration (MAC) of ISO alone or ISO with DEX (ISO-DEX, 1.6 µg/kg [bolus], followed by 2 µg/kg/h). Atropine was administered 30 minutes prior to hemorrhage in the ISO-DEX treatment. Ventilation was controlled (tidal volume of 12 mL/kg, positive end-expiratory pressure of 7 cm H2 O, respiratory rate of 16-20/min) under neuromuscular blockade. After recording baseline data, progressive withdrawal of 10%, 20%, and 30% of blood volume (HV10 , HV20 , and HV30 , respectively [measurements during hemorrhage, indicating x% of blood volume removed]) was followed by VR with autologous blood. MEASUREMENTS AND MAIN RESULTS: In 4 of 8 ISO dogs, hemorrhage decreased mean arterial pressure (MAP) < 60 mm Hg. Based on mean arterial pressure after hemorrhage, dogs were assigned to hypotensive (HG) and normotensive (NG) groups post hoc. During ISO, stroke index and cardiac index decreased with hemorrhage (P < 0.05), while VR normalized or increased these variables. The PPV (%, mean [range]) was increased by hemorrhage from 7 (5-9) to 20 (12-27) and 27 (17-40) at HV20 and HV30 , respectively, only in ISO dogs in the HG; PPV returned to baseline after VR. Dexmedetomidine caused increases in systemic vascular resistance (in dogs in HG and NG), and prevented the increase in PPV with hemorrhage. CONCLUSIONS: During ISO anesthesia, PPV increases in individuals prone to developing hypotension from hypovolemia. Because DEX prevents the increase in PPV associated with hypovolemia, PPV should not be used to guide VR in dogs that have been given DEX.