Direct Arterial Blood Pressure Research Articles

Canine preclinical safety evaluation of a multimodal nanoparticle agent (Nanotrast-CF800) for image-guided cancer surgery.

Surgical oncology often requires the use of contrast-enhanced cross-sectional imaging preoperatively to characterize solitary tumours and identify sentinel lymph nodes. Intraoperative optical guidance can effectively aid tissue-sparing tumour excision and locate sentinel lymph nodes. Nanotrast-CF800 (CF800) is a novel dual-modality contrast agent, which co-encapsulates iohexol and indocyanine green (ICG) within a liposomal nanoparticle. It was developed for preoperative and intraoperative imaging of solitary tumours and sentinel lymph node mapping and its efficacy has been demonstrated in preclinical animal models (Zheng et al. 2015). The objective of this study is to evaluate the safety profile of CF800 following intravenous administration in healthy dogs. Six research dogs were randomized into two groups. Group 1 received a low dose (1 mL/kg) and group 2 received a high dose (5 mL/kg). Dogs were placed under general anesthesia and a continuous rate infusion of CF800 was administered based on group allocation. Physiologic parameters including heart rate, respiratory rate, direct arterial blood pressure, cardiac output, and temperature were measured at set time points. Plasma concentrations of iohexol, ICG, and histamine were measured at set time points. Dogs underwent whole body computed tomography scans pre-injection, 2-, and 7-days post-injection (p.i.). Contrast enhancement was measured in select organ systems and great vessels at each time point. There were no significant changes in physiologic parameters following IV infusion of CF800 in all dogs. Plasma iohexol and ICG concentrations peaked at 1 day p.i., while histamine concentrations peaked at 30 minutes p.i. Significant contrast enhancement was noted within the liver, heart, aorta, and caudal vena cava on day 2 p.i., which was significantly different compared to baseline. Prolonged contrast retention within the liver was identified. Intravenous administration of CF800 was safe to use in healthy dogs with no significant systemic adverse effects.

Use of vasopressors for treatment of vasodilatory hypotension in dogs and cats by Diplomates of the American College of Veterinary Emergency and Critical Care.

To identify the most common practices of Diplomates of the American College of Veterinary Emergency and Critical Care (DACVECCs) as they relate to the recognition and treatment of hypotension in dogs and cats, particularly concerning the use of vasopressors in vasodilatory shock states. A survey regarding vasopressor use was sent to all active DACVECCs using the Veterinary Information Network. Questions focused on respondent characteristics, method of recognition of hypotension, triggers for initiation of vasopressor therapy, first- and second-line vasopressor choice, and methods of determining response to therapy. A total of 734 DACVECCs were invited to participate, and 203 Diplomates (27.7%) completed the survey. For both dogs and cats, the most common first-line vasopressor was norepinephrine (87.9% in dogs and 83.1% in cats). The most common second-choice vasopressor was vasopressin (44.2% in dogs and 39.0% in cats). Cutoff values for initiating vasopressor therapy varied between species and modality used for blood pressure measurement. In general, most DACVECCs chose to initiate vasopressor therapy at a Doppler blood pressure <90mmHg or a mean arterial pressure of <60 or <65mmHg when using oscillometric or direct arterial blood pressure measurements in dogs and cats. Most DACVECCs adhere to published human guidelines when choosing a first-line vasopressor. However, there is significant variability in blood pressure measurement technique, cutoffs for initiation of vasopressor use, and choice of second-line vasopressors.

Vascular hyperacetylation is associated with vascular smooth muscle dysfunction in a rat model of non-obese type 2 diabetes

BackgroundAdvanced type 2 diabetes mellitus (T2DM) accelerates vascular smooth muscle cell (VSMC) dysfunction which contributes to the development of vasculopathy, associated with the highest degree of morbidity of T2DM. Lysine acetylation, a post-translational modification (PTM), has been associated with metabolic diseases and its complications. Whether levels of global lysine acetylation are altered in vasculature from advanced T2DM remains undetermined. We hypothesized that VSMC undergoes dysregulation in advanced T2DM which is associated with vascular hyperacetylation.MethodsAged male Goto Kakizaki (GK) rats, a non-obese murine model of T2DM, and age-matched male Wistar rats (control group) were used in this study. Thoracic aortas were isolated and examined for measurement of global levels of lysine acetylation, and vascular reactivity studies were conducted using a wire myograph. Direct arterial blood pressure was assessed by carotid catheterization. Cultured human VSMCs were used to investigate whether lysine acetylation participates in high glucose-induced reactive oxygen species (ROS), a crucial factor triggering diabetic vascular dysfunction.ResultsThe GK rats exhibited marked glucose intolerance as well as insulin resistance. Cardiovascular complications in GK rats were confirmed by elevated arterial blood pressure and reduced VSMC-dependent vasorelaxation. These complications were correlated with high levels of vascular global lysine acetylation. Human VSMC cultures incubated under high glucose conditions displayed elevated ROS levels and increased global lysine acetylation. Inhibition of hyperacetylation by garcinol, a lysine acetyltransferase and p300/CBP association factor (PCAF) inhibitor, reduced high glucose-induced ROS production in VSMC.ConclusionThis study provides evidence that vascular hyperacetylation is associated with VSMC dysfunction in advanced T2DM. Understanding lysine acetylation regulation in blood vessels from diabetics may provide insight into the mechanisms of diabetic vascular dysfunction, and opportunities for novel therapeutic approaches to treat diabetic vascular complications.

ECHOCARDIOGRAPHY AND DIRECT ARTERIAL BLOOD PRESSURE MEASUREMENT IN CAPTIVE CHIMPANZEES (PAN TROGLODYTES) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL.

The effects of α-2 agonists on echocardiographic findings in great apes are not well documented, and knowledge of these effects would expand the understanding of cardiac examinations of chimpanzees under anesthesia with protocols using these drugs. Ten adult chimpanzees (Pan troglodytes), four males and six females, underwent echocardiographic examinations after anesthesia with dexmedetomidine, midazolam, and ketamine (phase 1). Four animals required isoflurane to achieve an adequate plane of anesthesia. Atipamezole was used to antagonize dexmedetomidine, and all remaining animals were placed on isoflurane (phase 2), and then a second echocardiogram was performed. Direct arterial blood pressure was monitored during the anesthetic event. Measurements and recordings were assessed for statistically significant differences between the two phases and sex. There were no significant differences between phases or sex for any two-dimensional echocardiographic measurement of systolic function, although interventricular septum thickness at end systole approached a significant decrease from phase 1 to phase 2 (P = 0.058) when sex was considered a between-subject factor. Left ventricular outflow tract (P = 0.017) and pulmonary artery (P = 0.028) velocities increased after reversal of the dexmedetomidine. Diastolic transmitral flow was consistent with grade 3 diastolic dysfunction (median early to late ventricular filling velocities (E/A) of 2.02, interquartile range [IQR], 1.53-2.13) with a nonsignificant decrease of E velocity and increase in A velocity and decreased E/A after reversal. Trace mitral and tricuspid regurgitation were common findings in the sample population. Arterial blood pressure significantly decreased between phase 1 and phase 2 (P < 0.01). All chimpanzees entered a hypotensive state (mean arterial pressure < 60 mm Hg) during phase 2. Although limited by the small number of chimpanzees, this study showed an increase in afterload, potential diastolic dysfunction, and a decrease in blood pressure after the antagonism of dexmedetomidine. Additional studies to further assess the effects of α-2 agonists in chimpanzees are warranted.

Evaluation of the effects of medial saphenous venous pressures as an indirect method of measurement of intra-abdominal pressures in the horse.

To evaluate the effect of changes in intra-abdominal pressure (IAP) on medial saphenous venous pressure (MSVP) and hemodynamics in normal horses. Experimental, in-vivo study. University Teaching Hospital. Convenience sample of 7 mixed breed horses; 5 geldings, and 2 mares. Pneumoperitoneum was induced in horses under standing sedation with carbon dioxide gas using a laparoscopic insufflator for a total of 60 minutes to simulate clinical elevation in IAP. Pressure was increased stepwise to 20mm Hg over 30 minutes, and maintained at that pressure for 30 minutes to evaluate the effect of sustained intra-abdominal hypertension. The MSVP and vital parameters were recorded, along with direct arterial blood pressure from the transverse facial artery. As IAP increased, MSVP increased in a stepwise manner, in concert with changes in IAP. The consistency in measurement between MSVP and IAP was high (intraclass correlation coefficient=0.92; P<0.001) and repeated measures correlation was excellent (r=0.98; P<0.001). Heart rate was unchanged over the course of the experiment (P=0.09), however, respiratory rate increased with increasing IAP (P<0.001). Arterial blood pressure also increased with insufflation (P<0.001), with a significant difference at an IAP of 15mm Hg (P=0.04). This report provides preliminary data demonstrating a strong correlation between equine MSVP and changes in IAP, similar to that observed in other species. Further investigations are needed to evaluate this relationship, and to confirm these results in clinical patients.

Doppler and oscillometric mean blood pressure best represent direct blood pressure measurements in anesthetized rhesus macaques (Macaca mulatta).

Indirect blood pressure measurements are often used to guide clinical decisions, but few studies have verified their agreement with direct arterial blood pressure in nonhuman primates. Here, the accuracy and precision of Doppler (DOP) and oscillometric (OS) [systolic (OSsys), mean (OSmean), and diastolic (OSdias)] blood pressure readings were assessed in rhesus macaques. DOP and OS were utilized to measure blood pressure values in nine anesthetized rhesus macaques, which were compared to direct measurements via a saphenous arterial catheter. All measurements were taken simultaneously every 5min for 60-240min. DOP and OSsys underestimated direct systolic arterial pressure with a bias ± precision of 10.21±6.37mmHg and 11.67±11.55mmHg, respectively. OSmean correlated well with direct mean arterial pressure with a bias ± precision of 7.25±7.35mmHg. DOP provided the better representation of systolic blood pressure, and OSmean provided a useful representation of mean arterial pressure in anesthetized rhesus macaques.

Evaluation of the Accuracy and Precision of the GE Dash 4000 Oscillometric Monitor for Blood Pressure Measurement in Anesthetized Female Dogs

Background: Indirect measurement of arterial blood pressure, such as the oscillometric method, is the most commonly used in clinical practice of dogs and cats. This method measures blood pressure values that are estimates of direct (invasive) arterial blood pressure values. Oscillometric devices are easy to use even for non-experienced personnel. However, there is considerable variation in accuracy and precision of blood pressure values measured by different oscillometric monitors. The present study aimed to determine the accuracy and precision of the GE Dash 4000 oscillometric monitor for arterial blood pressure measurement in anesthetized female dogs.Materials, Methods &amp; Results: Sixteen healthy adult female dogs received 0.3 mg/kg morphine as premedication and were anesthetized with propofol and isoflurane. A 22-gauge catheter was introduced into the dorsal pedal artery and connected to a rigid tubular system and a pressure transducer filled with heparinized solution to allow direct (invasive) measurement of systolic (SAP), mean (MAP) and diastolic arterial pressure (DAP). A blood pressure cuff was positioned proximal to the carpus and connected to the oscillometric device (GE-DASH 4000 monitor) in order to obtain indirect measurements of SAP, MAP and DAP. Cuff width was 40% of limb circumference. During anesthesia, invasive arterial blood pressure values were measured and recorded simultaneously with the oscillometric method. The Bland Altman method was used to evaluate agreement between the methods by calculating the bias (invasive - oscillometric) and limits of agreement. Percentages of differences between the methods with an error ≤ 10 mmHg and ≤ 20 mmHg were calculated. Results were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of noninvasive blood pressure methods. Weight and age of dogs were 7.6 ± 2.2 kg and 20 ± 17 months, respectively. A total of 195 pairs of measurements were obtained from 16 animals. Of these pairs, 146 were classified as normotension (SAP: 90 to 140 mmHg), 28 as hypertension (SAP &gt; 140 mmHg) and 21 as hypotension (SAP &lt; 90 mmHg). Bias values ± SD (95% limits of agreement) were: SAP, 5.0 ± 16.5 mmHg (-27.3 to 37.4 mmHg); MAP, -3.4 ± 14.3 mmHg (-31.4 to 24.6 mmHg); and DAP, 4.2 ± 11.8 mmHg (-18.9 to 27.4 mmHg). According to the ACVIM criteria, maximum values accepted for bias (± SD) are 10 ± 15 mmHg. Percentages of differences ≤ 10 mmHg and ≤ 20 mmHg were: SAP, 41% and 80%; MAP, 54% and 84%; and DAP, 64% and 91%. ACVIM recommendations are ≥ 50% for errors within 10 mmHg and ≥ 80% for errors within 20 mmHg.Discussion: MAP and DAP values obtained by the GE-DASH 4000 monitor matched the ACVIM criteria for validation of noninvasive methods. Conversely, SAP values did not meet all the criteria, and were not considered reliable. Limitations of the study include: a) most dogs were of low weight; b) the ACVIM criteria refer to SAP measurements, but in the present study, the same criteria were applied to MAP and DAP measurements; c) the majority of observations were obtained during normotension. We conclude that MAP and DAP measurements obtained by the GE Dash 4000 monitor met the ACVIM criteria for validation of noninvasive blood pressure monitors. Therefore, this monitor was considered to have adequate accuracy and precision for MAP and DAP measurements in anesthetized normotensive dogs. Under the conditions of this study, SAP measurements obtained by this monitor were not reliable.

Comparison of intraocular pressure, tear production and cardiorespiratory variables before and after induction of anaesthesia with either propofol or ketofol in dogs premedicated with midazolam

The objective of the present study was to compare the effects of propofol and ketofol on intraocular pressure, tear production and cardiorespiratory variables in dogs premedicated with midazolam. Six castrated adult mixed-breed dogs were used in a cross-over design with a one-week interval. Twenty minutes after premedication with midazolam (0.2 mg/kg), animals were assigned randomly to two groups and received either propofol (6 mg/kg) or ketofol (3 mg/kg; 1 : 1 mg/ml ratio) treatments intravenously. Intraocular pressure, tear production, heart rate, respiratory rate, rectal temperature and direct mean arterial blood pressure were measured at base (before induction), and at 5, 10, 15, 20 and 30 min after induction of anaesthesia. Blood gas samples were obtained at base (before induction), and at 5, 15 and 30 min after administration of treatments. Intraocular pressure showed significantly higher values at 5 min after induction in ketofol compared with propofol (16.1 ± 4.5 mm Hg vs 8.2 ± 1.2 mm Hg, respectively). There were no significant changes in tear production in either group. Significantly higher heart rate and mean arterial blood pressure were detected in ketofol at several time points. Respiratory depression occurred in both groups with no significant differences between them. In conclusion, although ketofol improved heart rate and mean arterial blood pressure and did not elicit more pronounced respiratory depression than propofol, it resulted in significantly higher values of intraocular pressure at 5 min after administration in dogs. Despite the small number of dogs in this study, our results indicate that ketofol should not be recommended for ophthalmic surgical procedures in dogs. Appropriate oxygenation should be provided when propofol is used for ophthalmic surgeries.

Short‐term Western Diet Induces Cardiometabolic Syndrome in Female Rats is Associated with Increased Cardiovascular Protein Lysine Acetylation.

The western diet (WD), which is rich in fat, carbohydrates, and refined sugars, is a major contributor to the global epidemic of metabolic syndrome in our modern society. Despite the well‐documented cardioprotection exhibited by the pre‐menopausal female population, studies have indicated that certain stressors may abolish this cardiovascular protection. Studies on the impact of the WD on the cardiometabolic profile of female cohorts remains limited. Lysine acetylation, a reversible posttranslational modification of histone and non‐histone proteins, has been closely associated with metabolic disorders. Based on these factors, we hypothesized that short‐term exposure to the WD alters cardiometabolic parameters in premenopausal rats and alters levels of lysine acetylation in the cardiovascular tissues. Adult female Wistar rats were randomized in two groups: Control Group (n=8) was assigned a regular chow diet and WD Group (n=12) received WD (40% fat, 43% carbohydrates, and 17% protein) for 17 weeks. Results showed that WD group exhibited increased body weight (376 ± 49 vs 305 ± 41g, p&lt;0.05), periabdominal fat content (30 ±11 vs 11 ±2g, p&lt;0.01), % body fat (8.1 ±1.0 vs 3.6 ±0.4%, p&lt;0.01), and serum triglyceride levels (56 ± 13 vs 25 ± 4 mg/dl, p&lt;0.01) compared to controls. Although the WD group exhibited significant increases in glucose intolerance (AUC: 17068.5 ± 730 vs. 13787.67± 814 a.u, p&lt;0.01) and insulin resistance (HOMA‐IR: 5.75 ± 0.9 vs. 3.25 ± 0.62 control, p&lt;0.05), no differences in fasting blood glucose and hemoglobin A1C were found. Using direct arterial blood pressure measurements via carotid artery catheterization, we observed increased systolic blood pressure (146.19 ±9.4 vs 126.22 ± 9.8 mmHg controls, p&lt;0.001), which is contradictory with previous studies. Our vascular reactivity studies revealed that short‐term WD markedly impaired endothelial‐dependent relaxation. Additionally, using DHE staining we found that aortas from the WD group exhibited augmented levels of oxidative stress (3.1‐fold increase vs. control, p&lt;0.001). Strikingly, levels of global lysine acetylation were markedly elevated in the aortas (2.2‐fold increase vs. control, p&lt;0.01) and heart (1.4‐fold increase vs. control, p&lt;0.05) of WD group. Levels of acetyltransferase PCAF were significantly upregulated in the aortas (2.2‐fold increase vs. control, p&lt;0.05). Interestingly, PCAF and deacetylase HDAC9 expression was diminished in hearts from WD group (30% reduction vs. control, p&lt;0.05) and (85% reduction vs. control, p&lt;0.05), respectively. Besides these cardiovascular alterations, the WD also led to the development of non‐alcoholic fatty liver disease (NAFLD) and robust increases in hepatic global lysine acetylation (3.0‐fold increase vs. control, p&lt;0.001). Taken together, our results demonstrated that, even under short‐term exposure, the WD negatively affects the metabolic and cardiovascular parameters of female rats and it is associated with elevated levels of global lysine acetylation in cardiometabolic tissues. This study will be further conducted to identify the specific proteins acetylated in blood vessels and heart from female population under WD regimes.Support or Funding InformationIn‐house Grant NYIT to MACSThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Non-invasive blood pressure measurement in ferrets (Mustela putorius furo) using high definition oscillometry

This study was conducted to validate the use of high definition oscillometry (HDO) for non-invasive blood pressure (NIBP) measurements in ferrets and to establish reference ranges for NIBP in minimally sedated, healthy, young adult ferrets (<4years of age). The bias, limits of agreement and correlation for HDO compared to direct arterial blood pressure (DABP) measurement were established in 14 anaesthetised ferrets. Measurements were performed at the forelimb, hind limb and tail under hypo- (<110mmHg), normo- (110–170mmHg) and hypertensive (>170mmHg) conditions. Although HDO correlated well with DABP (r>0.90), it showed significant proportional bias, whereby HDO generally underestimated DABP with hyper- and normotensive conditions, and overestimated DABP with hypotensive conditions. Measurements obtained from the hind limb showed higher bias than those obtained from the tail or forelimb (P<0.001). Based on the above, and for practical reasons, the tail was selected as the preferred site of cuff placement in ferrets. Subsequently, a cross-over study was performed in 10 ferrets to establish the minimum dose of butorphanol and midazolam needed to successfully obtain NIBP in 100% of cases. Using this dose (0.2mg/kg IM, each), reference intervals for NIBP from 63 healthy, young adult ferrets were established at 95–155mmHg (systolic), 69–109mmHg (mean) and 51–87mmHg (diastolic) arterial pressures.

Validity and reliability of Doppler ultrasonography and direct arterial blood pressure measurements in anaesthetized dogs weighing less than 5 kg

ObjectiveTo assess the validity and reliability of Doppler ultrasonography (DOP) as compared with invasive arterial blood pressure measurements in anaesthetized dogs weighing less than 5 kg. Study designControlled, prospective, clinical study. AnimalsA total of 41 privately owned dogs weighing less than 5 kg. MethodsThe dogs were anaesthetized, and an intra-arterial catheter was placed aseptically in the dorsal pedal artery of the pelvic limb to perform invasive blood pressure (IBP) measurement. The contralateral metatarsal surface of the foot was clipped in order to perform DOP. Both techniques were used to record blood pressure measurements every 5 minutes during surgical procedures. The blood pressure measurements were categorized into two groups: hypotensive [mean arterial pressure (MAP) < 60 mmHg] and normotensive (MAP between 60 and 120 mmHg). A linear mixed model was used to compare the DOP and IBP values. The results were evaluated according to the requirements of the American College of Veterinary Internal Medicine (ACVIM) guidelines for the validation of devices. ResultsDOP provided higher values compared to the systolic arterial blood pressure (SAP) and MAP of IBP measurements. The closest agreement between the two techniques was found for SAP; the bias was 8.8, and limits of agreement (LOA) were –32.9 and 50.4. Similar results were observed when the IBP technique was categorized. The closest agreement was for SAP in animals categorized as normotensive; the bias was 8.2, and LOAs were –32.8 and 49.2. The level of agreement between DOP and IBP did not meet the ACVIM recommendations. Conclusions and clinical relevanceOur results suggest there is poor agreement between DOP and IBP measurements in anaesthetized dogs weighing less than 5 kg. Hence, the use of DOP in these animals could be misleading.

The impact of MK-467 on sedation, heart rate and arterial blood pressure after intramuscular coadministration with dexmedetomidine in conscious cats

ObjectiveTo study the effects of MK-467, a peripheral α2-adrenoceptor antagonist, on sedation, heart rate and blood pressure after intramuscular (IM) coadministration with 25 μg kg−1 of dexmedetomidine in cats. Study designProspective, randomized, controlled, blinded, cross-over, experimental study. AnimalsA total of eight healthy, adult, neutered male cats. MethodsCats were administered five IM treatments at least 2 weeks apart, consisting of dexmedetomidine 25 μg kg−1 (D25), MK-467 600 μg kg−1 (M600) and D25 combined with 300, 600 and 1200 μg kg−1 of MK-467 (D25M300, D25M600 and D25M1200, respectively). Heart rate and direct arterial blood pressure were recorded via telemetry and sedation assessed prior to treatments and at intervals for 8 hours thereafter. ResultsHeart rate decreased significantly after all treatments with dexmedetomidine and remained below baseline up to 240 (D25), 20 (D25M300) and 3 minutes (D25M600 and D25M1200). Mean arterial pressure (MAP) increased with D25, remained unchanged with M600 and decreased over time with all combination treatments. The highest and lowest MAP after each treatment were 168±17 and 100±14 (D25), 157±18 and 79±11 (D25M300), 153±11 and 74±10 (D25M600), 144±12 and 69±7 (D25M1200) and 136±9 and 104±13 mmHg (M600). All treatments with dexmedetomidine produced sedation although its duration was significantly reduced by the addition of MK-467. Conclusions and clinical relevanceDexmedetomidine induced bradycardia and hypertension, which were attenuated by all three doses of MK-467. The duration of sedation was reduced by MK-467. MK-467 may improve the cardiovascular tolerance of IM dexmedetomidine in cats.

Clinical effects and pharmacokinetic variables of romifidine and the peripheral α2‐adrenoceptor antagonist MK‐467 in horses

ObjectivesTo investigate the effects of MK‐467 on sedation quality, and cardiopulmonary and pharmacokinetic variables in horses sedated intravenously (IV) with romifidine. Study designExperimental, randomized, crossover design. AnimalsSeven healthy mares. MethodsRomifidine (80 μg kg−1; R) and MK‐467 (200 μg kg−1; MK) were administered IV alone and in combination (R + MK). Levels of sedation and borborygmi were scored. Heart rate (HR), direct arterial blood pressure (ABP) and respiratory rate (fR) were recorded. Arterial and venous blood gas analyses were performed and venous plasma drug concentrations were measured. Pharmacokinetic parameters were calculated. Linear mixed modelling for repeated measures, contrasts of least square means by Bonferroni correction tests, one‐way anova for repeated measures with Bonferroni multiple comparison tests and paired Student's t‐tests were used to compare results within and between treatments as appropriate. Significance was set at p < 0.05. ResultsAfter R, ABP increased and HR and fR decreased significantly. After R + MK, HR, fR, systolic and mean ABP decreased. MK alone increased both HR and fR. After R, ABP was significantly higher than after R + MK. HR and fR were significantly higher after MK than after R and R + MK. Areas under the curve for sedation time were similar after R and R + MK. Intestinal activity decreased markedly after R and less after R + MK. Volume of distribution and clearance of romifidine were significantly higher and area under the concentration time curve extrapolated to infinity significantly lower after R + MK than after R. ConclusionsCombined romifidine and MK‐467 prevented the cardiovascular changes commonly seen with romifidine but did not affect sedation quality. Clinical relevanceCombined IV romifidine and MK‐467 can be used to attenuate the cardiovascular effects of romifidine, such as in horses with colic or undergoing general anaesthesia.

Indirect arterial blood pressure measurement in healthy anesthetized cats using a device that combines oscillometry with photoplethysmography.

We investigated the basic characteristics of indirect arterial blood pressure (ABP) measurement using a device that combines oscillometry and photoplethysmography in cats. Dobutamine was infused intravenously in four anesthetized cats. Direct ABP was measured by a catheter. Indirect ABP was measured from the left forelimb. Dobutamine significantly elevated both systolic arterial pressure (SAP) and mean arterial pressure (MAP) in a dose-dependent manner. The indirect SAP, MAP and diastolic arterial pressure (DAP) values were closely correlated with the direct ABP values (r=0.88, 0.89 and 0.83, respectively). The mean bias for SAP, MAP and DAP was 3.4, 0.2 and −2.4 mmHg, respectively. The indirect ABP measured by this device may be used to reliably monitor ABP changes in anesthetized cats.

Agreement of high definition oscillometry with direct arterial blood pressure measurement at different blood pressure ranges in horses under general anaesthesia

ObjectiveTo determine the agreement of high definition oscillometry (HDO) with direct arterial blood pressure measurements in normotensive, hypotensive and hypertensive horses during general anaesthesia. Study designExperimental study. AnimalsSeven healthy warmblood horses, aged 3–11 years, weighing 470–565 kg. MethodsMeasurements from a HDO device with the cuff placed around the base of the tail were compared with pressures measured invasively from the facial artery. High blood pressures were induced by intravenous (IV) administration of dobutamine (5 μg kg−1 minute−1) over ten minutes followed by norepinephrine (0.1 mg kg−1 IV) and low pressures by increasing the inspired fraction of isoflurane and administration of nitroglycerine (0.05 mg kg−1 IV). For analysis three pressure levels were determined: high (MAP>110 mmHg), normal (60 mmHg<MAP<110 mmHg) and low (MAP< 60 mmHg). Bland-Altman analysis was used for comparison between non-invasive and invasive measurements. ResultsA total of 245 paired measurements of systolic (SAP), mean (MAP) and diastolic (DAP) pressures were obtained. The HDO device underestimated blood pressure at hypertensive and normotensive levels and overestimated blood pressure at hypotensive levels. Best agreement was obtained for SAP and MAP within normotensive limits. At normotension, bias ± standard deviation for SAP, MAP and DAP were 0.1 ± 19.4 mmHg, 0.5 ± 14.0, 4.7 ± 15.6, respectively. At high pressure levels bias and SD were 26.1 ± 37.3 (SAP), 4.2 ± 19.4 (MAP), 1.5 ± 16.8 (DAP) and at low pressures -20.0 ± 20.9 (SAP), -11.4 ± 19.6 (MAP), -4.7 ± 20.1 (DAP), with HDO measurements at a MAP <50 mmHg often failing. Conclusion and clinical relevanceGood agreement with invasive arterial blood pressures was obtained with HDO at normotensive levels in horses. At high and low pressure ranges HDO was unreliable. Therefore, if haemodynamic instability is expected, invasive measurement remains preferable.

Noninvasive Hemodynamic Monitoring Devices

Noninvasive Hemodynamic Monitoring Devices

Effect of high zinc dose on haematological, lipids and protein patterns in dromedary camel- revised

Surgical lateralisation of the left carotid artery (LLCA) is frequently used to allow easy access to direct (invasive) arterial blood pressure and blood gas measurement in experimental settings. An experimental study was conducted in 15 dromedary camels of 2–12; average 4.9 ± 2.6 years and weighing 250–480, average 375.4 ± 74.3 kg. Animals were divided into 3 groups receiving one of 3 different surgical lateralization techniques. In group 1, the carotid was exposed over a continuous suture bed and covered with a wide skin flap. In group 2, a tunnel was made at the ventral part of skin flap to pass and cover the carotid artery. In Group 3, the carotid artery was loosely inserted subcutaneously between the sternocephalic and intertransverse muscles and held through a loop of non-absorbable suture material protruding with its free ends over the incision line to allow easier localisation and gentle grasping of the artery during experiment. Animals were observed for 7 days and any abnormalities noted. Base echocardiography was performed before collection of samples. Arterial and venous samples were collected twice from each group. Five animals died at variable period after the operations. Thrombosis in 4 animals (2 from group I and 2 from group II) was noted, and Post-mortem angiographaphy in one camel showed cerebral ischaemia.

The Cardiovascular Effects of Sevoflurane and Isoflurane After Premedication of Healthy Dogs Undergoing Elective Surgery

Sevoflurane and isoflurane are commonly used in veterinary anesthesia. The objective of this prospective, randomized, open-label clinical study was to compare the cardiovascular effects of sevoflurane and isoflurane via direct arterial blood pressure measurements and the lithium dilution cardiac output (LDCO) on premedicated healthy dogs undergoing elective tibial plateau leveling osteotomy (TPLO). Nineteen client-owned dogs were included. All dogs were premedicated with hydromorphone (0.05 mg/kg IV and glycopyrrolate 0.01 mg/kg subcutaneously). Ten dogs were anesthetized with sevoflurane and nine dogs were anesthetized with isoflurane. Eighteen dogs were instrumented with a dorsal pedal arterial catheter, and one dog had a femoral arterial catheter. All dogs had continuous, direct systolic (SAP), diastolic (DAP), and mean arterial (MAP) blood pressure readings as well as heart rate (HR), cardiac output (CO), cardiac index (CI), systemic vascular resistance (SVR), systemic vascular resistance index (SVRI), stroke volume variation (SVV), and pulse pressure variation (PPV) recorded q 5 min during the surgical procedure. There was no significant statistical difference in all parameters between the sevoflurane and isoflurane treatment groups. Both sevoflurane and isoflurane inhalant anesthetics appear to have similar hemodynamic effects when used as part of a multimodal anesthetic protocol in premedicated healthy dogs undergoing an elective surgical procedure.

High-definition oscillometry and direct arterial blood pressure measurement

High-definition oscillometry and direct arterial blood pressure measurement

Evaluation of a rapid pressor response test in healthy cats

To evaluate angiotensin I and angiotensin II rapid pressor response tests in healthy cats. 6 purpose-bred sexually intact male cats. Telemetric blood pressure (BP) implants were placed in all cats. After 2 weeks, cats were anesthetized for challenge with exogenous angiotensin I or angiotensin II. Continuous direct arterial BP was recorded during and immediately after IV administration of boluses of angiotensin I or angiotensin II at increasing doses. Blood pressure responses were evaluated for change in systolic BP (SBP), change in diastolic BP (DBP), and rate of increase of SBP by 4 observers. Following IV angiotensin I and angiotensin II administration, transient, dose-dependent increases in BP (mean ± SEM change in SBP, 25.7 ± 5.2 and 45.0 ± 9.1; change in DBP, 23.4 ± 4.7 mm Hg and 36.4 ± 7.8 mm Hg; for 100 ng of angiotensin I/kg and angiotensin II/kg, respectively) and rate of increase of SBP were detected. At angiotensin I and II doses < 2.0 ng/kg, minimal responses were detected, with greater responses at doses ranging from 20 to 1,000 ng/kg. A significant effect of observer was not found. No adverse effects were observed. The rapid pressor response test elicited dose-dependent, transient increases in SBP and DBP. The test has potential as a means of objectively evaluating the efficacy of various modifiers of the renin-angiotensin-aldosterone system in cats. Ranges of response values are provided for reference in future studies.