Colloid osmotic pressure after hemorrhage and replenishment with Oxyglobin Solution, hetastarch, or whole blood in pregnant sheep

Objective To compare plasma colloid osmotic pressure (COP) of both maternal and fetal blood, before and after hemorrhage, and replenishment with Oxyglobin Solution (Biopure Corporation, Cambridge, MA, USA), hetastarch or whole blood in pregnant ewes. Study design Prospective, randomized study. Animals A total of 17 adult Rambouillet ewes at 131 (128–133) [median (minimum, maximum)] days gestation, weighing 56 (46, 63) kg. Methods Ewes and fetuses were chronically instrumented with catheters in a maternal jugular vein, maternal carotid artery and fetal femoral artery. Twenty milliliters per kilograms of blood were removed from each ewe over 1 hour. The ewes were then given 20 mL kg^?1 of either Oxyglobin Solution (n = 5), hetastarch (n = 6), or autologous whole blood (n = 6) IV. Maternal plasma COP was measured before hemorrhage, after hemorrhage, after replenishment, and 1 and 2 hours later. Fetal plasma COP was measured after maternal hemorrhage and 2 hours after maternal volume replenishment. Results Median COP of all ewes before hemorrhage was 20 (16, 24) mm Hg and after hemorrhage (p < 0.05), decreased to 16 (11, 19) mm Hg. After volume replenishment, the COP of the Oxyglobin Solution group was 22 (21, 25) mm Hg, the autologous whole blood group was 17 (16, 22) mm Hg and the hetastarch group was 20 (17, 21) mm Hg. The COP of the Oxyglobin Solution group was significantly greater (p < 0.05) than the COP of the hetastarch group immediately and 60 minutes after volume replenishment, and greater (p < 0.05) than that of the autologous whole blood group at 60 minutes after volume replenishment. The COP of all the fetuses after maternal hemorrhage was 16 (12, 19) mm Hg and at 120 minutes after maternal volume replenishment was 15 (11, 18) mm Hg. There were no differences in COP between or within any of the fetal groups. Conclusions When used to treat blood loss, Oxyglobin Solution increases plasma COP more than an equal volume of hetastarch in the first hour following administration. Maternal administration of Oxyglobin Solution did not alter fetal COP. Clinical relevance Oxyglobin Solution is a more potent colloid than hetastarch. Oxyglobin Solution did not appear to translocate fluid from the fetal to maternal circulation.     

Effect of body position on the arterial partial pressures of oxygen and carbon dioxide in spontaneously breathing,conscious dogs in an intensive care unit

Objective – To evaluate the effect of body position on the arterial partial pressures of oxygen and carbon dioxide (PaO₂, PaCO₂), and the efficiency of pulmonary oxygen uptake as estimated by alveolar‐arterial oxygen difference (A‐a difference). Design – Prospective, randomized, crossover study. Setting – University teaching hospital, intensive care unit. Animals – Twenty‐one spontaneously breathing, conscious, canine patients with arterial catheters placed as part of their management strategy. Interventions – Patients were placed randomly into lateral or sternal recumbency. PaO₂ and PaCO₂ were measured after 15 minutes in this position. Patients were then repositioned into the opposite position and after 15 minutes the parameters were remeasured. Measurements and Main Results – Results presented as median (interquartile range). PaO₂ was significantly higher (P=0.001) when patients were positioned in sternal, 91.2 mm Hg (86.0–96.1 mm Hg), compared with lateral recumbency, 86.4 mm Hg (73.9–90.9 mm Hg). The median change was 5.4 mm Hg (1.1–17.9 mm Hg). All 7 dogs with a PaO₂<80 mm Hg in lateral recumbency had improved arterial oxygenation in sternal recumbency, median increase 17.4 mm Hg with a range of 3.8–29.7 mm Hg. PaCO₂ levels when patients were in sternal recumbency, 30.5 mm Hg (27.3–32.7 mm Hg) were not significantly different from those in lateral recumbency, 32.2 mm Hg (28.3–36.0 mm Hg) (P=0.07). The median change was ?1.9 mm Hg (?3.6–0.77 mm Hg). A‐a differences were significantly lower (P=0.005) when patients were positioned in sternal recumbency, 21.7 mm Hg (17.3–27.7 mm Hg), compared with lateral recumbency, 24.6 mm Hg (20.4–36.3 mm Hg). The median change was ?3.1 mm Hg (?14.6–0.9 mm Hg). Conclusions – PaO₂ was significantly higher when animals were positioned in sternal recumbency compared with lateral recumbency, predominantly due to improved pulmonary oxygen uptake (decreased A‐a difference) rather than increased alveolar ventilation (decreased PaCO₂). Patients with hypoxemia (defined as PaO₂<80 mm Hg) in lateral recumbency may benefit from being placed in sternal recumbency. Sternal recumbency is recommended to improve oxygenation in hypoxemic patients.     

Potential risks,prognostic indicators,and diagnostic and treatment modalities affecting survival in dogs with presumptive aspiration pneumonia: 125 cases (2005–2008)

Objective – To evaluate a clinical population of dogs diagnosed with presumptive aspiration pneumonia (AP) and determine diagnostic and treatment modalities contributing to survival. Design – Retrospective study. Setting – A university veterinary teaching hospital in an urban setting. Animals – One hundred and twenty‐five dogs with presumed AP treated from 2005 to 2008. Interventions – None. Measurements and Main Results – Dogs with presumptive AP identified by a review of medical records had an overall survival of 81.6% (102/125). Male large‐breed dogs (mean 24.9 kg; 82/125) were overrepresented and were more likely to develop AP in this study population. Recent anesthesia had been performed in 16% (20/125), and vomiting was reported in 64% (80/125). The most common radiographic findings were a predominantly alveolar pattern (187/272, [68.8%] total lung lobes) in the right middle lung lobe (80/115, [69.6%]). A mean of 2 lung lobes were involved radiographically, and the relationship between survival and the number of lung lobes affected was statistically significant (P=0.04). Neutrophilia with a left shift was common with no significant change on consecutive daily evaluations. The mean PaO₂ was 77.7 mm Hg (SD, 17.5 mm Hg) (range, 40.7–100 mm Hg) with a median alveolar‐arterial gradient of 41.1 mm Hg (range, 8.1–81.8 mm Hg). In this study population, 37.6% (47/125) of dogs had microbial cultures performed and of these, 76.6% (36/47) were positive for growth; Escherichia coli (38.8%), Mycoplasma spp. (21.3%), Pasturella spp. (19.1%), and Staphylococcus spp. (17%) were the most common isolates in either single or multiagent infections. No treatment modality was statistically associated with increased survival. Colloid therapy was a negative prognostic indicator. Conclusions – In this study the overall prognosis for AP was good. Patients with only 1 affected lung lobe appeared more likely to survive. Supportive treatment modalities are warranted for the hospitalized patient, although no individual treatment method was found to be clearly superior to others.     

Evaluation of an indirect oscillometric blood pressure monitor in normotensive and hypotensive anesthetized dogs

Objective – To determine the accuracy and precision of an oscillometric noninvasive blood pressure device as a predictor of invasive direct blood pressure in healthy anesthetized hypotensive and normotensive dogs. Design – Prospective observational study. Setting – University teaching hospital. Animals – Eight crossbred adult dogs. Interventions – Anesthesia was induced with propofol and maintained with isoflurane. A catheter was placed in the dorsal pedal artery to record systolic, mean, and diastolic arterial blood pressures (aSAP, aMAP, and aDAP, respectively). The noninvasive blood pressure device cuff was placed around the contralateral front limb to record noninvasive systolic, mean, and diastolic blood pressure (nSAP, nMAP, and nDAP). Two states of blood pressure (BP) were studied: baseline state was established by keeping end‐tidal isoflurane concentration at 1.2±0.1%. The hypotensive state was achieved by maintaining the same isoflurane concentration while withdrawing approximately 40% of the animal's blood volume until aMAP was stable at approximately 40 mm Hg. At the end of the study, blood was returned to the animal and it was allowed to recover from anesthesia. Measurements and Main Results – Agreement between the direct and indirect BP measurements was determined by the Bland‐Altman method. The SAP and MAP but not DAP bias varied significantly between each BP state. Normotensive absolute biases (mean [SD]) for SAP, MAP, and DAP were ?14.7 mm Hg (15.5 mm Hg), ?16.4 mm Hg (12.1 mm Hg), and ?14.1 mm Hg (15.8 mm Hg), respectively. Absolute biases during the hypotensive state for SAP, MAP, and DAP were ?32 mm Hg (22.6 mm Hg), ?24.2 mm Hg (19.5 mm Hg), and ?16.8 mm Hg (17.2 mm Hg), respectively. Conclusion – The oscillometric device was not reliably predictive of intra‐arterial BP during hypotension associated with acute hemorrhage.     

Measurement of plasma colloid osmotic pressure in normal thoroughbred neonatal foals

A normal plasma colloid osmotic pressure (COP) interval was established for foals and compared to values for adult horses. Plasma samples were obtained from 38 Thoroughbred foals that had normal findings on postfoaling examination and 10 healthy Thoroughbred adult horses. Samples were analyzed using a commercially available colloid osmometer. Fifty samples were obtained from 38 foals. Twelve foals had 2 samples taken, 1 during the 1st 24 hours of life and the 2nd between 24 and 72 hours of life. For foals with 2 samples, only 1 randomly selected value was used in group analysis. Total plasma protein, albumin, and globulin concentrations were measured on all samples from foals. The mean measured plasma COP for foals was 18.8 +/- 1.9 mm Hg for the 38 samples analyzed. Measured plasma COP did not differ significantly over the time period examined for either the 12 paired samples (P = .13) or with regression analysis of the 38 samples (P = .13). Calculation of mean COP, based on previously published quadratic equations using total protein, albumin, and globulin concentrations, underestimated mean measured foal COP values except for when total protein measured by refractometer was used in the Landis-Pappenheimer equation. In conclusion, the plasma COP interval (95% CI: 15.0 mm Hg, 22.6 mm Hg) obtained for healthy foals in this study was found to be lower than that of healthy adult Thoroughbreds (20.6 +/- 0.7 mm Hg, P = .006).     

Comparison of ultrasonic Doppler flow monitor,oscillometric, and direct arterial blood pressure measurements in ill dogs

Objective – To compare blood pressure measurements obtained via ultrasonic Doppler flow monitor (DOP) and 2 oscillometric noninvasive blood pressure monitors (CAR and PAS) to invasive blood pressure (IBP) in hospitalized, conscious dogs with a range of blood pressures. Design – Prospective clinical study. Setting – University teaching hospital. Animals – Eleven client‐owned dogs aged between 4 months and 11.5 years (median 6 y), and weighing between 5.8 and 37.5 kg (median 30.2 kg). Interventions – Blood pressure measurement. Measurements and Main Results – Three consecutive measurements of systolic, diastolic, and mean arterial pressure (MAP) were recorded for each of the 3 indirect devices (only systolic for DOP), along with concurrent IBP measurements. The data were categorized into 3 groups: hypotensive (direct MAP<80 mm Hg), normotensive (80 mm Hg≤direct MAP≥100 mm Hg), and hypertensive (direct MAP>100 mm Hg). Each indirect method was compared with the corresponding direct arterial pressure using the Bland‐Altman method. Within the hypotensive group, each indirect method overestimated the corresponding IBP. Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements underestimated the corresponding IBP. The remaining indirect measurements overestimated the corresponding IBP. Within the hypertensive group, DOP and CAR systolic measurements underestimated the corresponding IBP, and the remaining indirect measurements overestimated the corresponding IBP. In hypertensive dogs oscillometric systolic measurements were more accurate than MAP. In hypotensive dogs MAP measurements were more accurate than systolic measurements. All indirect measurements were most accurate in hypertensive dogs. Conclusions – The noninvasive blood pressure monitors in our study did not meet the validation standards set in human medicine. However, CAR diastolic and MAP measurements within the normotensive group, CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were close to these standards. All indirect measurements showed greater bias during hypotension. Precision was poorer for all indirect systolic measurements than for MAP.     

Clinical comparison of three methods to measure blood pressure in nonsedated dogs

OBJECTIVE: To determine arterial blood pressure in client-owned dogs, using direct arterial puncture, oscillometry, and Doppler ultrasonography in a clinical setting. DESIGN: Prospective study. ANIMALS: 8 clinically normal client-owned dogs. PROCEDURE: Blood pressures of nonsedated dogs were measured simultaneously, using each of the 3 methods. Mean values obtained were compared with published mean values. Ability of noninvasive methods (Doppler ultrasonography and oscillometry) to accurately predict results of the invasive method, and relationships between blood pressure and age, body weight, and degree of patient anxiety were determined. RESULTS: Calculated ranges of values (mean +/- 2 SD) determined by direct arterial puncture were: systolic pressure, 114 to 194 mm Hg; diastolic pressure, 66 to 102 mm Hg; and mean pressure, 85 to 129 mm Hg. Ranges determined by use of oscillometry were: systolic, 110 to 190 mm Hg; diastolic, 35 to 107 mm Hg; and mean, 78 to 138 mm Hg. Ultrasonographic and oscillometric values did not accurately predict direct values, but mean values of systolic and mean pressures were similar among methods. Relationships were not detected between age or body weight and blood pressure. Significant differences in blood pressure were not detected between anxious and nonanxious dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Mean values of systolic, diastolic, and mean arterial blood pressure measured in nonsedated client-owned dogs, using invasive and noninvasive methods in a clinical setting, are comparable with those determined for acclimatized, trained, or sedated dogs. However, results of noninvasive methods may not accurately reflect direct values.     

Indirect arterial blood pressure measurement in nonsedated Irish wolfhounds: reference values for the breed

Arterial blood pressure measurements were obtained from 158 healthy Irish wolfhounds using the oscillometric technique to establish reference values for the breed. In contrast to other sight hounds, Irish wolfhounds have low arterial blood pressure. Mean systolic pressure for the group was 116.0 mm Hg. Mean diastolic pressure was 69.2 mm Hg, and the mean value for mean arterial pressure was 87.8 mm Hg. Blood pressure measurements were higher in older wolfhounds than in young dogs. There was no difference between systolic and mean arterial blood pressures in lateral recumbency compared to standing position. However, diastolic pressure was slightly lower when standing. Calm dogs had lower pressure than anxious wolfhounds. There was a significant interaction between the effects of age, gender, and mood on systolic, diastolic, and mean arterial blood pressure values.     

Direct colloid osmometry in healthy New World camelids

Background: Direct colloid osmometry provides an objective assessment of the oncotic effects of crystalloid or colloidal fluid therapy, which is especially useful in monitoring fluid therapy of critically ill camelids due to their tendency toward nonspecific hypoproteinemia with increased risk of developing edema and ascites. Objectives: The aims of this study were to measure colloid osmotic pressure (COP) of alpacas and llamas, determine its correlation with concentrations of total protein (TP) and total solids (TS), as well as both albumin (A) and globulin (G) concentrations in the same model (A+G), and evaluate the effects of sample type and storage conditions on COP. Methods: Blood was collected from clinically healthy alpacas (n=23) and llamas (n=22) into heparin tubes. COP of fresh whole blood (COP_FB) and plasma (COP_FP) was determined using a membrane osmometer. For 20 alpacas, COP of refrigerated whole blood (COP_RB) and frozen plasma (COP_FrP) was also measured. Correlations between COP_FB and TS, TP, and A+G concentrations were assessed by simple and multiple regression analysis to model potential predictors. Results: Median COP_FB from alpacas (24.6 mmHg, range 19.3–28.1) was not significantly different from that of llamas (25.3 mmHg, range 22.5–33.7). Sample type or storage conditions did not affect COP. Measured COP had a strong positive linear correlation with TS, TP, and A+G concentrations in alpacas (r²=.7, .74, and .88, respectively). In llamas, COP correlated best with TS concentration (r²=.59), whereas correlation with TP and A+G concentrations was poor (r²=.19 and .25, respectively). Conclusion: COP can be measured using heparinized whole blood or plasma, either fresh or stored. Direct measurement is recommended whenever quantitative knowledge of COP is required in clinical or research setting. Further studies are needed to verify if the poor association of COP with TP found in this study can be generalized to llamas.     

Continuous positive airway pressure administered via face mask in tranquilized dogs

Objective – To evaluate the tolerance of a continuous positive airway pressure (CPAP) mask in tranquilized dogs and compare PaO₂ in arterial blood in dogs receiving oxygen with a regular face mask or CPAP mask set to maintain a pressure of 2.5 or 5 cm H₂O. Design – Prospective, randomized clinical study. Setting – University teaching hospital. Animals – Sixteen client‐owned dogs without evidence of cardiopulmonary disease were studied. Interventions – Eight animals were randomly assigned to each of 2 treatment groups: group A received 2.5 cm H₂O CPAP and group B received 5 cm H₂O CPAP after first receiving oxygen (5 L/min) by a regular face mask. Animals were tranquilized with acepromazine 0.05 mg/kg, IV and morphine 0.2 mg/kg, IM. An arterial catheter was then placed to facilitate blood sampling for pHa, PaO₂, and PaCO₂ determinations before and after treatments. Direct mean arterial pressure, heart rate, respiratory rate, and temperature were also recorded after each treatment. Measurements and Main Results – CPAP administration was well tolerated by all animals. The mean arterial pressure, heart rate, respiratory rate, temperature, PaCO₂, and pHa, did not differ at any time point between groups. Differences were seen in oxygenation; in group A, PaO₂ significantly increased from a mean of 288.3±47.5 mm Hg with a standard mask to a mean of 390.3±65.5 mm Hg with the CPAP mask and in group B, PaO₂ increased similarly from 325.0±70.5 to 425.2±63.4 mm Hg (P<0.05); no differences were detected between the 2 CPAP treatments. Conclusions – In healthy tranquilized dogs noninvasive CPAP is well tolerated and increases PaO₂ above values obtained when using a regular face mask.     

Effect of antivenin dose on outcome from crotalid envenomation: 218 dogs (1988–2006)

Objective – To determine whether the dose of antivenin administered is associated with a difference in survival of crotalid‐envenomated dogs. A secondary objective was to determine whether other covariables affect survival. Design – Retrospective study (1988–2006). Setting – Private referral center and university small animal teaching hospital. Animals – Two hundred and eighteen dogs with evidence of crotalid envenomation and treatment with equine‐derived antivenin. Interventions – Administration of antivenin. Measurements and Main Results – Patient signalment, physical and clinicopathologic data at time of presentation, treatments, complications of antivenin therapy, length and cost of hospitalization, and outcome were recorded. Confidence intervals were determined for the difference in median number of vials administered and for median dosage for patients that lived versus died. Penalized logistic regression was performed to evaluate the effect of other covariables on survival. The median age of affected dogs was 3 years (range 6 w–12 y) with a median weight of 25.7 kg (range 1.95–86.4 kg). The median number of antivenin vials administered was 1.0 (range 1.0–10.0). Acute and chronic reactions were reported in 7% (16/218) and 0.9% (2/218) of dogs, respectively. Nine of 218 dogs (4.1%) died. The median number of vials administered to the nonsurvivors and survivors were 2.0 (range 1–5 vials) and 1.0 (range 1–10 vials), respectively. The median number of vials received was significantly different in dogs that died versus those that lived (P<0.05). Increased heart rate (P=0.02) and petechiation (P=0.04) were associated with decreased likelihood of survival, while diphenhydramine (P=0.02) and fluoroquinolone (P=0.046) administration was associated with increased likelihood of survival. The median duration of hospitalization was 1.0 day (range 2 h–22 d). The median cost of hospitalization was US$1592.00 (range US$267.20–US$6738.00). Conclusion – The administration of more vials of antivenin is potentially associated with negative outcome; however, a causal relationship has not been established. Controlled, prospective studies are needed to optimize antivenin administration.     

Variance of indirect blood pressure measurements and prevalence of hypertension in clinically normal dogs

In a series of 3 studies, indirect blood pressure measurements were obtained to define normal variance, identify hypertension, and estimate the prevalence of hypertension in apparently healthy dogs. In part 1, we measured values in 5 clinically normal dogs twice weekly for 5 weeks in a home setting. Mean +/- SD systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) was 150 +/- 16 and 86 +/- 13 mm of Hg, respectively. The DAP significantly (P less than 0.01) decreased with repeated measurements over the 5-week period. In part 2, we assessed the variation between blood pressures measured in a clinic vs those measured in the home. Within a 2-week period, measurements were obtained from 10 clinically normal dogs in a private veterinary clinic and again in their home. Significant differences were not observed between clinic and home measurements of SAP and DAP; however, heart rate was significantly (P less than 0.05) higher in the clinic. In part 3, SD about the SAP and DAP mean values were determined in 102 clinically normal dogs. Canine hypertensive status was determined, using statistical methods and data from 102 clinically normal dogs. Values of SAP greater than 202 mm of Hg and DAP greater than 116 mm of Hg were determined to be 2 SD beyond the mean and, therefore, were interpreted to be hypertensive. Approximately 10% of the 102 apparently healthy dogs measured in this study were considered hypertensive on the basis of these criteria. In addition, a border zone of suspected hypertension was estimated, using the mean + 1.282 SD. The SAP border zone was between 183 and 202 mm of Hg, whereas the DAP border zone was between 102 and 113 mm of Hg. Of the 102 dogs, 12 had values within these zones of suspected hypertension.     

Effect of adenosine infusion on isoflurane MAC in dogs.

Adenosine is a potent analgesic in people and reduces the MAC of halothane in dogs. The purpose of this study was to determine whether adenosine reduces the MAC of isoflurane in dogs. Seven beagles (four males and three females) were anesthetized and randomly assigned to receive adenosine (0.3 mg kg^–1 minute^–1; 6 mL kg^–1 hour^–1, IV) or saline (0.9%, 6 mL kg^–1 hour^–1IV). After an interval of ≥7 days, each dog was reanesthetized and treated with the alternate infusion. Anesthesia was induced and maintained with isoflurane in oxygen. Dogs were intubated and instrumented for measurement of mean systemic arterial blood pressure and airway concentration of isoflurane and end‐tidal partial pressure of carbon dioxide. The MAC for isoflurane was determined using the tail‐clamp technique. Baseline MAC values were 1.25 (1.15, 1.35)% [median (minimum, maximum)] and 1.25 (1.05, 1.45)% before the saline and adenosine treatments, respectively. After 2 hours of infusion with saline or adenosine, MAC values were not different (p = 0.156) and were 1.25 (0.95, 1.35)% and 1.05 (1.00, 1.25)%, respectively. Two hours following the end of each infusion, the MAC values for saline and adenosine treatment groups differed significantly (p = 0.015), but by no more than the normal variation inherent in this study, and were 1.15 (1.15, 1.35)% and 1.05 (1.05, 1.25)%, respectively. Mean arterial blood pressure was 93 (74, 123) mm Hg for saline treated dogs and 67 (52, 72) mm Hg (p = 0.008) during adenosine infusion. End‐tidal carbon dioxide was not different between the two treatment groups. We conclude that adenosine administered at 0.3 mg kg^–1 minute^–1had no effect on isoflurane MAC in dogs, but decreased mean arterial blood pressure.     

Indication,management, and outcome of brachycephalic dogs requiring mechanical ventilation

Objectives – To evaluate the frequency, and need for mechanical ventilation (MV) in a population of brachycephalic dogs (BD) compared with non‐BD. Also, to describe the pre‐MV abnormalities, ventilator settings used, the cardiovascular and pulmonary monitoring results and complications encountered in the same BD population. In addition, we sought to identify factors associated with successful weaning and describe outcomes of BD requiring MV. Design – Retrospective observational study (1990–2008). Setting – University Small Animal Teaching Hospital. Animals – Fifteen BD managed with MV. Interventions – None. Measurements and Main Results – Signalment, indication for MV, ventilator settings, arterial blood gas values, duration of MV, complications, and outcome were recorded for each patient enrolled in study. BD were more likely to receive MV than non‐BD (P=0.036). Out of the 15 dogs that fulfilled the inclusion criteria 7 (47%) underwent MV for impending respiratory fatigue, 6 (40%) for hypoxemia and 2 for hypercapnea. The most common underlying disease was aspiration pneumonia. Duration of MV ranged from 2 to 240 hours (median 15 hours). Seven patients were weaned (47%). Seven dogs had a temporary tracheostomy tube and 5 of them (71%) were weaned. Dogs that were weaned had a significantly greater preweaning trial PaO₂/FiO₂ ratio than those that were not (359 ± 92 versus 210 ± 57 mm Hg, P=0.025). No significant difference for weaning success between dogs with and those without a tracheostomy was detected (P=0.132). The discharge rate was 27% (all from the respiratory fatigue group). Conclusion – Among all dogs admitted to ICU, BD were more likely to receive MV than non‐BD. Aspiration pneumonia was frequently identified as the underlying cause of respiratory compromise. The survival rate for BD undergoing MV was not markedly different from previous studies. Weaning of BD from MV may be facilitated by employing preemptive strategies such as performing tracheostomy tube placements.     

Evaluation of platelet function in dogs with cardiac disease using the PFA‐100 platelet function analyzer

Background: Cardiac disease has the potential to alter platelet function in dogs. Evaluation of platelet function using the PFA‐100 analyzer in dogs of multiple breeds and with a broad range of cardiac conditions would help clarify the effect of cardiac disease on platelets. Objectives: The objective of this study was to assess differences in closure time (CT) in dogs with cardiac disease associated with murmurs, when compared with that of healthy dogs. Methods: Thirty‐nine dogs with cardiac murmurs and turbulent blood flow as determined echocardiographically were included in the study. The dogs represented 23 different breeds. Dogs with murmurs were further divided into those with atrioventricular valvular insufficiency (n=23) and subaortic stenosis (n=9). Fifty‐eight clinically healthy dogs were used as controls. CTs were determined in duplicate on a PFA‐100 analyzer using collagen/ADP cartridges. Results: Compared with CTs in the control group (mean±SD, 57.6±5.9 seconds; median, 56.5 seconds; reference interval, 48.0–77.0 seconds), dogs with valvular insufficiency (mean±SD, 81.9±26.3 seconds; median, 78.0 seconds; range, 52.5–187 seconds), subaortic stenosis (71.4±16.5 seconds; median, 66.0 seconds; range, 51.5–95.0 seconds), and all dogs with murmurs combined (79.6±24.1 seconds; median, 74.0 seconds; range, 48.0–187 seconds) had significantly prolonged CTs (P<.01). Conclusions: The PFA‐100 analyzer is useful in detecting platelet function defects in dogs with cardiac murmurs, most notably those caused by mitral and/or tricuspid valvular insufficiency or subaortic stenosis. The form of turbulent blood flow does not appear to be an important factor in platelet hypofunction in these forms of cardiac disease.     

Comparison of cardiac output determined by arterial pulse pressure waveform analysis method (FloTrac/Vigileo) versus lithium dilution method in anesthetized dogs

Objective – To compare the determination of cardiac output (CO) via arterial pulse pressure waveform analysis (FloTrac/Vigileo) versus lithium dilution method. Design – Prospective study. Setting – University teaching hospital. Animals – Six adult dogs. Interventions – Dogs were instrumented for CO determinations using lithium dilution (LiDCO) and FloTrac/Vigileo methods. Direct blood pressure, heart rate, arterial blood gases, and end‐tidal isoflurane (ETIso) and CO₂ concentrations were measured throughout the study while CO was manipulated with different depth of anesthesia and rapid administration of isotonic crystalloids at 60 mL/kg/h. Measurements and Main Results – Baseline CO measurements were obtained at 1.3% ETIso and were lowered by 3% ETIso. Measurements were obtained in duplicate or triplicate with LiDCO and averaged for comparison with corresponding values measured continuously with the FloTrac/Vigileo method. For 30 comparisons between methods, a mean bias of ?100 mL/kg/min and 95% limits of agreement between ?311 and +112 mL/kg/min (212 mL/kg/min) was determined. The mean (mL/kg/min) of the differences of LiDCO?Vigileo=62.0402+?0.8383 × Vigileo, and the correlation coefficient (r) between the 2 methods 0.70 for all CO determinations. The repeatability coefficients for the individual LiDCO and FloTrac/Vigileo methods were 187 and 400 mL/kg/min, respectively. Mean LiDCO and FloTrac/Vigileo values from all measurements were 145 ± 68 mL/kg/min (range, 64–354) and 244 ± 144 mL/kg/min (range, 89–624), respectively. The overall mean relative error was 48 ± 14%. Conclusion – The FloTrac/Vigileo overestimated CO values compared with LiDCO and the relative error was high, which makes this method unreliable for use in dogs.     

Plasma Taurine Concentrations in Normal Dogs and in Dogs With Heart Disease

Plasma taurine concentrations were determined in 76 dogs with dilated cardiomyopathy (DCM), 28 dogs with acquired valvular disease (AVD), and 47 normal (control) dogs. The data were collected at 2 referral centers. The Animal Medical Center, New York, NY (AMC), and the University of California, Davis (UCD), and the studies were conducted independently. Different anticoagulants (sodium citrate at AMC and lithium heparin at UCD) were used to collect the plasma samples. Paired analysis of samples showed a significant difference in plasma taurine concentrations, depending on the anticoagulant used. Consequently, results from each clinic were analyzed separately. Plasma taurine concentrations were significantly higher in dogs with AVD (median, 133 nmol/mL; range, 25 to 229 nmol/mL) than in control dogs (median, 63 nmol/mL; range 44 to 224 nmol/mL) and dogs with DCM (median, 72 nmol/mL; range, 1 to 247 nmol/mL) at AMC (P= .001). The number of dogs with AVD at UCD was too small to draw meaningful conclusions. At UCD, the median plasma taurine concentration was 98 nmol/mL (range, 28–169 nmol/mL) in dogs with AVD, 75 nmol/mL (range, 0.1–184 nmol/mL) in dogs with DCM, and 88 nmol/mL (range 52–180 nmol/mL) in control dogs. There were no significant differences in plasma taurine concentrations between dogs with DCM and the control dogs at either hospital. Congestive heart failure and administration of cardiac medication had no significant effect on plasma taurine concentrations. Plasma taurine concentration was low (<25 nmol/mL) in 17% (13/76) of the dogs with DCM. Seven of the 13 dogs with low plasma taurine concentrations were Cocker Spaniels or Golden Retrievers. It was concluded that most dogs with DCM do not have low plasma taurine concentrations. However, certain breeds or individual dogs may have low plasma taurine concentrations in association with DCM. Whether this association is causal or not is unknown. The significance of the high plasma taurine concentrations in dogs with AVD is also unknown.     

Accuracy and precision of the portable StatPal II and the laboratory-based NOVA stat profile 1 for measurement of pH, P(CO2), and P(O2) in equine blood

OBJECTIVE: To investigate the accuracy and precision of the portable, battery-powered StatPal II and the laboratory-based NOVA StatProfile 1 blood gas and pH analyzers for use in analysis of equine blood. STUDY DESIGN: Patient sample comparison and whole blood tonometry. SAMPLE POPULATION: Patient sample comparison: 125 arterial or venous blood samples from 49 healthy, awake, or anesthetized horses or ponies. Tonometry: venous blood samples from 11 healthy Thoroughbred horses. MATERIALS AND METHODS: Arterial and venous blood taken from awake and anesthetized equine patients was placed in an ice-water bath, then analyzed within 30 minutes of collection. Bias and limits of agreement between analyzers in measurement of pH, P(CO2), and P(O2) were calculated according to the method of Bland and Altman. Tonometry, using analyzed gases with a range of P(O2) of 28 to 286 mm Hg and P(CO2) of 21 to 85 mm Hg, was performed on equine whole blood or blood with abnormally high (55%) or low (20%) hematocrit. Samples were introduced directly from the tonometer into the analyzers. Inaccuracy (% of target value) and imprecision (coefficient of variation) were determined for each instrument. In addition, results of analysis of blood samples introduced into the analyzers at 36 degrees C, 0 to 3 degrees C, and 22 degrees C were compared. RESULTS: In the patient sample comparisons, bias between analyzers (StatPal-NOVA) for measurement of P(O2) less than 60 mm Hg was -0.33+/-6.2 mm Hg (x +/-2 SD) and for P(O2) between 60 and 110 mm Hg bias was -1.48+/-9.2 mm Hg. Bias was 46.5+/-67 mm Hg (significantly different from bias at the lower P(O2) levels) for measurement of P(O2) values of 111 to 505 mm Hg, and at P(O2) values greater than 110 mm Hg, bias increased with increasing P(O2). During the course of the study, a significant shift in bias between instruments occurred for P(CO2) and pH measurement, coincident with a change of P(CO2) and pH electrodes in the NOVA and use of a new lot of StatPal sensors. Bias (StatPal-NOVA) for P(CO2) before and after the electrode change was -3.74+/-4.2 and -0.88+/-6.8 mm Hg, and bias for pH before and after the electrode change was 0.026+/-0.034 and -0.024+/-0.038. The change in bias was significant (P<.05). In the whole blood tonometry trials, mean recovered values of P(CO2) and P(O2) from blood with a normal hematocrit ranged from 94% to 109% of target values for StatPal and from 98% to 107% for NOVA. Imprecision ranged from 3.3% to 5.3% for StatPal and from 2.2% to 4.3% for NOVA. With extremes of hematocrit (55% and 20%), StatPal's mean recovered P(CO2) values were 115% and 112% of the target value of 21 mm Hg, whereas NOVA's recovered P(CO2) values were similar to those recovered from samples with normal hematocrit. Introduction of cold blood samples (0 to 3 degrees C) into StatPal resulted in P(CO2) readings that were approximately 2 mm Hg lower than those of 22 degrees C and 36 degrees C samples (P<.05). No other effects of sample temperature were found for either instrument. CONCLUSIONS: StatPal and NOVA are of similar accuracy and demonstrate acceptable precision for measurement of P(CO2) and P(O2) in equine blood with values in the normal arterial and venous range. Mean recovered values during tonometry differed by as much as 10% between instruments, indicating that they should not be used interchangeably for a single patient or for a group of subjects in a research setting. CLINICAL RELEVANCE: The StatPal is a portable blood gas analyzer of acceptable accuracy and precision, for clinical or investigational work in horses.     

Evaluation of a new oscillometric blood pressure monitor in isoflurane-anesthetized dogs

Objective This study was conducted to evaluate the performance of a new veterinary oscillometric noninvasive blood pressure (NIBP) monitor in anesthetized dogs. Study design Assessment was made to determine how closely indirect measurements were associated with direct measurements, and if there were statistically significant differences between the measurements by site. Animals Six mongrel dogs weighing 27.8 ± 2.9 kg. Methods Dogs were anesthetized with thiopental and maintained with isoflurane, which was delivered with controlled ventilation. Direct pressure measurements were obtained via a percutaneously placed arterial catheter. A range of systolic arterial pressures (SAP) were achieved by changing the isoflurane concentrations. Sites of cuff placement for indirect measurements were identified as metacarpus, metatarsus, and anterior tibial. Results At pressures below 80 mm Hg, indirect systolic measurements averaged 4 ± 3 mm Hg, higher than the direct values. At normal and high levels, indirect systolic measurements underestimated direct values by 18 ± 6 and 23 ± 6 mm Hg, respectively. Diastolic and mean pressure measurements followed the same trend, with indirect values being lower than the direct arterial pressures. Systolic, diastolic and mean arterial pressure measurements differed by cuff‐placement site. Conclusions When analyzed by site and level, indirect systolic and mean arterial blood pressures during hypotension were essentially the same as direct pressures. However, at pressures within the normal or high range, indirect measurements underestimated the direct pressures. Clinical relevance Noninvasive blood pressure measurements with a new oscillometric monitor provided an excellent means of detecting arterial hypotension in anesthetized dogs. The metatarsal site for cuff placement was slightly better than the metacarpal or anterior tibial site, considering that the regression line was closest to complete equality between the indirect and direct measurements for SAP.     

The Cardiac Biomarker NT-proBNP Is Increased in Dogs with Azotemia

Background: Amino‐terminal probrain natriuretic peptide (NT‐proBNP) has been proposed as a useful biomarker for heart disease in dogs. In humans, decreased glomerular filtration rate (GFR) increases NT‐proBNP. Objective: To investigate whether decreased GFR as indicated by plasma creatinine concentration is associated with increased NT‐proBNP in dogs without heart disease. Animals: Four groups of dogs: healthy (n= 39), azotemic (n= 36), heart disease (n= 37), and congestive heart failure (CHF) (n= 7) presented to 2 teaching hospitals. Methods: Prospective observational cohort study. Plasma creatinine concentration and NT‐proBNP were measured in every dog. Nonparametric tests were used to compare the differences among groups. The median and actual results for each group were compared with the manufacturer's recommended and previously published suggestions for cut‐off values for diagnosis of heart disease. Results: Median (range) plasma creatinine concentration was 1.47 (1.06–1.70), 4.36 (1.74–15.6), 1.22 (0.69–1.91), and 1.45 (0.63–1.64) mg/dL and median (range) NT‐proBNP was 118 (2–673), 556 (37–1,819), 929 (212–5,658), and 3,144 (432–5,500) pmol/L for the healthy, azotemic, heart disease, and CHF groups, respectively. Pair‐wise comparison indicated a significant difference among all groups for NT‐proBNP (P≤ .049). Plasma creatinine concentration was significantly higher in the azotemic group compared with other groups (P < .001) but there was no significant among other groups. Application of 3 recommended cut‐off values led to misclassification of dogs with azotemia as having heart disease. Conclusions: Azotemia results in NT‐proBNP being increased to concentrations reported as diagnostic of heart disease or heart failure in dogs. Care should be employed when interpreting the results of NT‐proBNP in patients with known or possible increased plasma creatinine concentration.