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and intestinal lymphatic trunks that drain into the thoracic duct. 6 Lymphatic hypertension has been proposed as a possible reason that TDL for treatment of chylothorax may fail 13 ; CCA may prevent lymphatic hypertension by allowing direct drainage
Hypertension in dogs is increasingly recognized as a complication of several diseases such as renal dysfunction, 1 hyper- and hypothyroidism, 2 hyperadrenocorticism, 3 diabetes mellitus, 4 pheochromocytoma, hepatic disease, 5 and intracranial
ultrasonographic methods in the detection of systolic hypertension in dogs . J Vet Intern Med 2003 ; 17 : 65 – 72 . 10.1111/j.1939-1676.2003.tb01325.x 30. Evans R Horstman C Conzemius M . Accuracy and optimization of force platform gait analysis in
SUMMARY
Objective
To determine reliability of noninvasive methods of arterial oxyhemoglobin saturation (SpO2 ), end-tidal CO2 concentration (PEtCO2 and blood pressure (BP) determination during periods of hypoxemia and systemic arterial BP perturbations.
Animals
7 healthy, conditioned dogs weighing 19 to 22 kg.
Procedure
3 pulse oximeters, 2 capnometers, and 2 oscillometric BP monitors were used to measure oxygen-carrying capacity of the blood, heart rate, ventilatory status and arterial BP changes during hypoxemia, and altered arterial BP. Pulse oximeter-derived SpO2 and PEtCO2 were determined during rapidly induced plateaus of hypoxia (decreased fractional inspired oxygen concentration [FiO2 ) and altered systemic arterial BP. A lead-II ECG was used to monitor heart rate.
Results
Pulse oximetry provided an accurate assessment of fractional oxyhemoglobin saturation (SaO2 ) at SpO2 > 70%. As SaO2 decreased from 70%, the magnitude of the SpO2 error increased (20% error at SpO2 < 30%). The PEtCO2 was accurate at PaCO2 , ranging from 30 to 55 ± 5 mm of Hg under all experimental conditions. When PaCO2 was > 55 mm of Hg, both capnometers produced values that were as much as 20 mm of Hg less than the corresponding PaCO2 . Mean BP was least dependent on pulse wave quality, consistently underestimating mean arterial BP by approximately 10 mm of Hg.
Conclusions and Clinical Relevance
The pulse oximeters tested provided an accurate estimation of SaO2 at SpO2 > 70%. A PEtCO2 value > 55 mm of Hg may represent hypercapnia that is more profound than indicated. Systolic BP determinations were most accurate during hypotensive states and least accurate during hypertension. Diastolic BP measurements were generally more accurate during hypertension than normotension. Accuracy is not appreciably affected by hypotension resulting from vasodilation or blood loss. The tendency to underestimate systemic arterial BP should not interfere with trend detection during unstable clinical conditions. (Am J Vet Res 1998;59:205–212)
oscillometric monitor in anesthetized pigs subjected to changes in ABP, (2) test the ability of the device to track directional changes in ABP, and (3) assess the ability of the device to detect arterial hypotension and hypertension in reference to direct
Abstract
Objective
To determine sedative, analgesic, and basic cardiovascular effects of xylazine administered to pigs.
Animals
6 two-month-old Landrace x Large White pigs.
Procedure
Xylazine was administered IV at increasing dosages (1, 2, 4, 8, and 16 mg/kg of body weight) to otherwise unmedicated, conscious pigs, and the aforementioned effects were determined before xylazine administration and 2, 5, 10, and 15 minutes later. Then a higher xylazine dosage was given after the 15-minute measurements were taken.
Results
None of the xylazine dosages induced sufficient analgesia to prevent painful response to tail clamping; considerable excitation with vocalization and without appreciable sedative effect was observed at all dosages. At lower dosages, cardiovascular effects were characterized by bradycardia and biphasic blood pressure response; initial hypertension was followed by hypotension. At higher dosages, severe hypotension with moderate bradycardia was followed by marked bradycardia and return to normal baseline values or slight increase in blood pressure.
Conclusion
Xylazine did not induce adequate sedative or analgesic effects in pigs at any dosage tested; however, cardiovascular effects were considerable. These effects of xylazine differ from those observed in other domestic species. (Am J Vet Res 1997;58:99–102)
tepoxalin treatment. Systemic hypertension had also been diagnosed in the dog prior to inclusion in the study; however, systolic arterial blood pressure (170 mm Hg) did not change as a result of tepoxalin treatment. In contrast, the serum creatinine
Summary
In an effort to better understand the role of vasodilators in the management of pulmonary hypertension associated with chronic heartworm disease (hwd), pulmonary hemodynamic measurements were obtained from 7 experimentally infected, anesthetized dogs before and after hydralazine administration (mean dose, 1.96 mg/kg of body weight). Five dogs were maintained on room air, while 2 were maintained on 100% oxygen during the hydralazine study. The hemodynamic effect of hydralazine in dogs with hwd was evaluated, using heart rate, cardiac index, mean pulmonary artery pressure, mean arterial pressure, total pulmonary resistance, total systemic resistance, total systemic resistance/total pulmonary resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, and left and right ventricular double products ([mean arterial pressure × heart rate] and [mean pulmonary artery pressure × heart rate], respectively). Responders were defined as those in which total pulmonary resistance decreased ≥ 20% without an increase in mean pulmonary arterial pressure and in which heart rate increase was ≤ 10%. Comparison was also made between maximal hemodynamic effect of hydralazine with that after 100% oxygen administration for 15 minutes to previously normoxemic dogs (n = 5). Significance was determined if P < 0.05, using the paired t-test.
Hydralazine induced significant reductions in mean pulmonary and systemic arterial pressures and total pulmonary resistance, with no significant change in heart rate, cardiac index, total systemic resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, or right and left ventricular double products. Four (57%) of the 7 dogs studied were considered responders. Pretreatment cardiac index, mean pulmonary artery pressure, and total pulmonary resistance did not allow differentiation of responders from nonresponders. However, pretreatment right ventricular end diastolic pressure was significandy less in responders than in nonresponders. Two dogs sustained hypotension after hydralazine administration, but no dogs had significant tachycardia. In dogs with experimentally induced hwd, treatment with hydralazine had significantly greater effect on cardiac index and mean pulmonary and systemic arterial pressures and resistance than did administration of 100% oxygen. These data indicate that further study of vasodilators for treatment of hwd-induced pulmonary hypertension may be warranted.
the American College of Veterinary Internal Medicine (ACVIM) consensus statement on hypertension has similar recommendations for veterinary patients. 3 Chimpanzees ( Pan troglodytes ) are a common species in zoological institutions and often serve in
have been noted, possibly related to underlying hypertension. 4 In most instances of cardiovascular death, animals are found dead without premonitory clinical signs observed by caretakers. 1 The most common necropsy finding is myocardial fibrosis