Evaluation of arterial blood gases and arterial blood pressures in brachycephalic dogs.
ABSTRACT Brachycephalic dogs (BD) are prone to congenital upper airway obstruction (brachycephalic syndrome, BS). In humans suffering from sleep apnea, upper airway obstruction is known to cause hypertension. There is no information regarding the influence of BS in dogs on cardiorespiratory physiology.
BD are prone to lower P(a) O(2), higher P(a) CO (2), and hypertension compared with meso- or dolicocephalic dogs (MDD).
Eleven BD and 11 MDD.
After a questionnaire was completed by the owner, a physical examination was performed. Height and thoracic circumferences were measured. Arterial blood gases, electrolyte concentrations, and packed cell volume (PCV) were measured. Systolic (SAP), mean (MAP), and diastolic (DAP) arterial blood pressure recordings were performed.
A total of 7 French and 4 English bulldogs met the inclusion criteria. The control group consisted in 6 Beagles, 2 mixed breed dogs, 1 Staffordshire Bull Terrier, 1 Parson Russell Terrier, and 1 Australian Cattle Dog. Statistically, BD had lower P(a) O(2), higher P(a) CO2, and higher PCV when compared with controls (86.2 ± 15.9 versus 100.2 ± 12.6 mmHg, P = .017; 36.3 ± 4.6 versus 32.7 ± 2.6 mmHg, P = .019; 48.2 ± 3.5 versus 44.2 ± 5.4%, P = .026, respectively). Also, they had significantly higher SAP (177.6 ± 25.0 versus 153.5 ± 21.7 mmHg, P = .013), MAP (123.3 ± 17.1 versus 108.3 ± 12.2 mmHg, P = .014), and DAP (95.3 ± 19.2 versus 83.0 ± 11.5 mmHg, P = .042). BD with a P(a) CO (2) >35 mmHg were significantly older than those with a P(a) CO (2) ≤35 mmHg (58 ± 16 and 30 ± 11 months, P = .004).
Results of this study suggest that some BD are prone to lower P(a) O(2), higher P(a) CO (2), and hypertension when compared with MDD. Age may be a contributing factor.
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ABSTRACT: To evaluate the effect of dilution of blood samples with sodium heparin on blood gas, electrolyte, and lactate measurements in dogs. Sample Population-Venous blood samples collected from 6 adult dogs of various breeds. Syringes were prepared with anticoagulant via 1 of 4 techniques, and the residual volume of liquid heparin in each type of prepared syringe was determined. Blood gas values and other selected clinicopathologic variables were measured in whole blood samples after collection (baseline) and after aliquots of the samples were diluted with heparin via 1 of the 4 manual syringe techniques. By use of a tonometer, whole blood samples were adjusted to 1 of 3 oxygen concentrations (40, 100, or 600 mm Hg) and the PO2 values were measured at baseline and subsequent to the 4 heparin dilutions. The 4 syringe techniques resulted in 3.9%, 9.4%, 18.8%, and 34.1% dilutions of a 1-mL blood sample. Compared with baseline values, dilution of blood samples with liquid heparin significantly changed the measured values of PCO2, PO2, and base deficit and concentrations of electrolytes and lactate. Of the variables assessed, measurement of ionized calcium concentration in blood was most affected by heparin dilution. These findings in dogs indicate that dilution of blood samples with heparin can be a source of preanalytical error in blood gas, electrolyte, and lactate measurements. Limiting dilution of blood samples with heparin to < 4% by volume via an evacuation technique of syringe heparinization is recommended.American Journal of Veterinary Research 04/2005; 66(4):656-60. · 1.35 Impact Factor
- The American journal of physiology 05/1953; 173(1):77-81. · 3.28 Impact Factor
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ABSTRACT: The chemoreflexes are important modulators of sympathetic activation. The peripheral chemoreceptors located in the carotid bodies respond primarily to hypoxaemia. Central chemoreceptors located in the region of the brainstem respond to hypercapnia. Activation of either the hypoxic or hypercapnic chemoreflex elicits both hyperventilation and sympathetic activation. During apnoea, when the inhibitory influence of stretch of the pulmonary afferents is eliminated, there is a potentiation of the sympathetic response to both hypoxia and hypercapnia. This inhibitory influence of the pulmonary afferents is more marked on the sympathetic response to peripheral compared with central chemoreceptor activation. The arterial baroreflexes also have a powerful inhibitory influence on the chemoreflexes. This inhibition is again more marked with respect to the peripheral compared with central chemoreflexes. In patients with hypertension, there is a marked increase in the sympathetic and ventilatory response to hypoxaemia. During apnoea, with elimination of the inhibitory influence of breathing, the sympathetic response in untreated mild hypertensive patients is strikingly greater than that seen in matched normotensive controls. This potentiated peripheral chemoreflex sensitivity in hypertension may be explained in part by impaired baroreflex function in these patients. Enhanced peripheral chemoreflex sensitivity is also evident in patients with obstructive sleep apnoea. This peripheral chemoreflex enhancement is not explained by obesity, as obese individuals have a selective potentiation of the central chemoreceptors with peripheral chemoreflex responses similar to those seen in lean controls. Increased sensitivity to hypoxaemia has important implications in patients with obstructive sleep apnoea who experience repetitive and severe hypoxaemic stress. Tonic activation of the chemoreflex may also contribute to the high levels of sympathetic activity evident even during normoxic daytime wakefulness in sleep apnoea patients. Administration of 100% oxygen in patients with sleep apnoea results in reductions in heart rate, blood pressure and central sympathetic outflow. In patients with heart failure, the central chemoreflex response to hypercapnia is markedly and selectively enhanced. This increased central chemoreflex sensitivity may contribute to the development of central sleep apnoea in heart failure patients. Administration of 100% oxygen does not lower sympathetic activity in patients with heart failure, providing further evidence against any peripheral chemoreflex potentiation. The peripheral and central chemoreflexes have powerful effects on sympathetic activity in both health and disease and may contribute importantly to disease pathophysiology, particularly in conditions such as hypertension, obstructive sleep apnoea and heart failure.Acta Physiologica Scandinavica 04/2003; 177(3):377-84. · 2.55 Impact Factor