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- Author or Editor: Charles T. Talbot x
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Abstract
OBJECTIVE
To define reference intervals (RIs) for arterial blood gas (aBG) measurements in healthy, nonsedated, dolichocephalic, and mesocephalic (nonbrachycephalic) dogs at approximately 1,535 m above sea level and compare these findings with healthy, nonsedated, brachycephalic dogs living at the same altitude.
ANIMALS
120 adult nonbrachycephalic dogs and 20 adult brachycephalic dogs.
METHODS
Cases were prospectively enrolled from October 2021 to June 2022. Dogs were enrolled from the community or after presentation for wellness examinations or minor injuries including lacerations, nail injuries, and lameness. Physical examinations and systolic blood pressure (sBP) measurements were obtained before blood sample collection. Arterial blood was collected from the dorsal pedal artery or femoral artery. After data collection, brachycephalic dogs underwent pre- and postexercise tolerance assessments.
RESULTS
The mean and RI values for arterial pH (7.442; 7.375 to 7.515), partial pressure of oxygen in arterial blood (Pao 2; 78.3; 59.2 to 92.7 mm Hg), partial pressure of carbon dioxide in arterial blood (Paco 2; 28.0; 21.5 to 34.4 mm Hg), saturation of arterial oxygen (Sao 2; 98.4; 84.3% to 101.4%), HCO3 (18.9; 14.9 to 22.4 mmol/L), concentration of total hemoglobin (ctHb; 17.5; 13.4 to 21.1 g/dL), and sBP (133; 94 to 180 mm Hg) were established for healthy nonbrachycephalic dogs at 1,535-m altitude. All aBG measurements were statistically and clinically different from those previously reported for dogs at sea level. Brachycephalic dogs had significantly lower Pao 2 and Sao 2 (P = .0150 and P = .0237, respectively) and significantly higher ctHb (P = .0396) compared to nonbrachycephalic dogs acclimatized to the same altitude; the nonbrachycephalic RIs were not transferable to the brachycephalic dogs for Pao 2.
CLINICAL RELEVANCE
This study represents the first collation of aBG measurements for healthy nonbrachycephalic dogs acclimatized to an altitude of 1,535 m. Additionally, this study identified differences in arterial oxygenation measurements between brachycephalic and nonbrachycephalic dogs. RIs in brachycephalic dogs need to be established.
Abstract
OBJECTIVE
To determine if tissue oxygen saturation (StO2) correlates with oxygen delivery (DO2) and/or cardiac output (CO) in a canine hemorrhagic shock model.
ANIMALS
8 healthy purpose-bred dogs.
METHODS
Dogs were anesthetized, and hemorrhagic shock was induced by withdrawing up to 60% of total blood volume, targeting a mean arterial pressure (MAP) of 40 mm Hg. The withdrawn blood was returned to the patient in 2 equal aliquots. Data was collected at 4 time points: 10 minutes after MAP was stabilized under anesthesia (time point [TP]-1), 10 minutes after up to 60% of blood volume was removed to target a MAP of 40 mm Hg (TP2), 10 minutes after the return of 50% of shed blood (TP3), and 10 minutes after the return of the remaining 50% of shed blood (TP4). Total blood volume withdrawn, StO2, CO, heart rate, and MAP were recorded, and DO2 was calculated at each TP.
RESULTS
Mean StO2 significantly decreased between TP1 (77.8% [± 9.54]) and TP2 (44.8% [± 19.5]; P < .001 vs TP1). Mean StO2 increased to 63.1% (± 9.85) at TP3, but remained significantly lower compared to TP1 (P = .002). There was no difference between mean StO2 at TP4 (82.5% [± 12.6]) versus TP1 (P = .466). StO2 has a strong, positive correlation to both CO (r = 0.80; P < .001) and DO2 (r = 0.75; P < .001).
CLINICAL RELEVANCE
A decrease in StO2 may be used in conjunction with physical examination findings and diagnostic parameters to support a diagnosis of shock. The return of shed blood was correlated with increases in StO2, DO2, and CO, suggesting that StO2 may be used as a marker of adequate resuscitation.
Abstract
OBJECTIVE
To determine whether shock index (SI) positively correlates with percentage blood loss and negatively correlates with cardiac output (CO) in a canine hemorrhagic shock model and whether SI and metabolic markers may be used as end point targets for resuscitation.
ANIMALS
8 healthy Beagles.
PROCEDURES
Between September and December 2021, dogs underwent general anesthesia for experimental induction of hypotensive shock, with the total volume of blood removed, CO, heart rate, systolic blood pressure, base excess, blood pH, and concentrations of hemoglobin, lactate, ionized calcium recorded, and SI calculated at 4 time points (TPs): after anesthetic induction when the dog had been stable for 10 minutes (TP1), 10 minutes after the mean arterial pressure stabilized to a target of 40 mm Hg following jugular removal of up to 60% blood volume to induce hemorrhagic shock (TP2), 10 minutes after autotransfusion of 50% of the removed blood (TP3), and 10 minutes after autotransfusion of the remaining 50% of the removed blood (TP4).
RESULTS
Mean SI increased between TP1 (1.08 ± 0.35) and TP2 (1.90 ± 0.73) and did not return to the prehemorrhage values for TP3 or TP4. SI correlated positively with percentage blood loss (r = 0.583) and negatively with CO (r = –0.543).
CLINICAL RELEVANCE
An increase in SI may support diagnosis of hemorrhagic shock; however, SI cannot be used as the sole end point of resuscitation. Significant differences in blood pH, base excess, and lactate concentration suggested they may be useful markers of hemorrhagic shock and need for blood transfusion.
