Comparison of Doppler,oscillometric, auricular and carotid arterial blood pressure measurements in isoflurane anesthetized New Zealand white rabbits

ObjectiveTo assess agreement between carotid arterial pressure and auricular arterial, thoracic limb Doppler or thoracic limb oscillometric blood pressure measurements.Study designProspective experimental study.AnimalsSix adult New Zealand white rabbits.MethodsRabbits were anesthetized with isoflurane in oxygen at 1, 1.5 and 2 MAC on two separate occasions. Catheters in the auricular and the contralateral external carotid artery were connected to calibrated pressure transducers via non-compliant tubing. Inflatable cuffs of width equal to approximately 40% of the limb circumference were placed above the carpus on both thoracic limbs with a Doppler transducer placed distal to the cuff on one. Systolic (SAP) and mean (MAP) arterial blood pressure measurements were obtained at each dose, on each occasion. Agreement between measurement techniques was evaluated by repeated measures Bland Altman analysis with carotid pressure as the reference. Variation in bias over the measurement range was evaluated by regression analysis.ResultsCarotid MAP and SAP ranged from 20 to 65 mmHg and 37 to 103 mmHg respectively. Bias and 95% limits of agreement for auricular and oscillometric MAP were 7 (0–14) and ?5 (?21–11) mmHg, respectively, and for auricular, oscillometric and Doppler SAP were 23 (8–37), ?2 (?24–20) and 13 (?14–39) mmHg, respectively. Bias varied significantly over the measurement range (p < 0.001) for all three SAP techniques but not for MAP measurements.Conclusions and clinical relevanceLimits of agreement for all measurements were large but less so for MAP than SAP. Variation in bias with SAP should be considered when using these measurements clinically.     

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

Objective

To 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.

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 mmHgResultsA 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.     

Comparison of high definition oscillometric and Doppler ultrasound devices with invasive blood pressure in anaesthetized dogs

Objective To use the American College of Veterinary Internal Medicine (ACVIM) validation criteria to evaluate the performance of high definition oscillometric (HDO) and Doppler blood pressure measurement techniques against invasive blood pressure measurements in anaesthetized dogs. Study design Prospective clinical study. Animals Twenty client‐owned dogs. Materials and Methods Invasive blood pressure was measured using a catheter inserted into a pedal artery and an electronic transducer. The sites of cuff placement for the HDO measurements were the mid antebrachium or the proximal tail and, for the Doppler technique, the distal tibia. Agreement between invasive and non‐invasive blood pressure measurements was estimated by the Bland–Altman method. Results Only 10% and 34% of Doppler measurements were within 10 and 20 mmHg of invasive blood pressure values, respectively. The Doppler device failed to meet the ACVIM validation criteria for blood pressure measurement devices. The best agreement between HDO and invasive blood pressure measurement technique was observed for mean arterial blood pressure (MAP); 67% and 95% of readings were within 10 and 20 mmHg of invasive blood pressure values respectively. In addition, 52% and 87% of diastolic arterial blood pressure (DAP) measurements were within 10 and 20 mmHg of invasive readings. High definition oscillometric readings did not meet ACVIM recommended limits for SAP. Conclusion and clinical relevance The Doppler technique overestimated and the HDO device showed limited agreement with invasive blood pressure measurement in anaesthetized dogs. High definition oscillometry met most of the ACVIM requirements for MAP and DAP while the Doppler technique did not.     

Comparison of femoral and auricular arterial blood pressure monitoring in pigs

Objective To compare arterial blood pressure measurements obtained from the femoral and auricular arteries in anaesthetized pigs. Study design Prospective experimental study. Animals Fifteen female Large White pigs were used weighing 21.3 ± 2.3 kg. Methods The pigs were anaesthetized with tiletamine/zolazepam and xylazine administered intramuscularly, and anaesthesia maintained with isoflurane delivered in oxygen/nitrogen. Arterial oxygen partial pressures were maintained between 11.3 and 13.3 kPa and PaCO₂ between 4.6 and 6.0 kPa. Monitoring included electrocardiogram, capnography and invasive blood pressure. The auricular and femoral arteries were catheterized for continuous systolic (SAP), diastolic (DAP) and mean arterial pressure (MAP) measurements. Measurements were recorded every 15 minutes. Statistical analysis involved a Bland–Altman plot analysis. Results The mean difference ± confidence intervals between the femoral and the auricular arterial diastolic, systolic and mean blood pressure measurements during hypotension were 2 ± 7, 2 ± 5 and 2 ± 5 mmHg respectively. In conditions of normotension mean difference ± confidence intervals, of femoral and auricular arterial blood pressure measurements of diastolic, systolic and mean blood pressure were 4 ± 5, 3 ± 7 and 4 ± 4 mmHg respectively. In conditions of increased arterial blood pressure, mean difference ± confidence intervals, of femoral and auricular arterial blood pressure measurements of diastolic, systolic and mean blood pressure were 4 ± 5, 3 ± 8 and 4 ± 4 mmHg respectively. Conclusion Auricular artery catheterization is easier and quicker to perform. Pressure measurements from the auricular artery compared well with the femoral artery. Clinical relevance We found that auricular arterial blood pressures were similar to femoral arterial values under the conditions of this experiment. We did not test extremes of blood pressure or significant alterations in body temperature.     

Comparison of arterial blood pressure measurements obtained invasively or oscillometrically using a Datex S/5 Compact monitor in anaesthetised adult horses

Objective

To assess agreement between noninvasive blood pressure (NIBP) oscillometrically-derived values from a multiparameter monitor (Datex Ohmeda S/5 Compact) with those obtained by invasive blood pressure (IBP) measurement in anaesthetised horses undergoing elective surgery.

Doppler blood pressure measurement in pigs during anaesthesia

To determine the accuracy of Doppler blood pressure measurement in anaesthetised pigs eight large white pigs (Sus scrofa) were anaesthetised with zolazepam and tiletamine as Zoletil 100 (4 mg/kg) and xylazine (2 mg/kg) by intramuscular injection followed by isoflurane in 100% oxygen. Blood pressure measurements were recorded using a Doppler probe on the radial artery and a catheter in the femoral artery connected to a transducer. The sample mean of the Doppler measurements were compared with the sample mean of the invasive systolic arterial blood pressure while accounting for the heart rate, end-tidal CO₂ and temperature. The predicted error of the Doppler was greatest when pigs were hypotensive and normothermic: 11 mmHg (CI: 6–15). Doppler measurements should be interpreted with caution in anaesthetised pigs that are hypotensive and normothermic.     

Comparison of respiratory function during TIVA and isoflurane anaesthesia in ponies Part II: breathing patterns and transdiaphragmatic pressure

ObjectiveTo compare breathing patterns and transdiaphragmatic pressure during total intravenous (TIVA) and isoflurane anaesthesia in ponies.Study designExperimental, cross–over study.AnimalsSix healthy ponies weighing 286 (233–388) ± 61 kg, age 13 (9–16) ± 3 years.MethodsFollowing premedication with romifidine [80 μg kg^?1 intravenously (IV)], general anaesthesia was induced with midazolam (0.06 mg kg^?1 IV) and ketamine (2.5 mg kg^?1 IV) and maintained with either isoflurane (Fe’Iso = 1.1%) (T-ISO) or an IV combination of romifidine (120 μg kg^?1 per hour), midazolam (0.09 mg kg^?1 hour^?1) and ketamine (3.3 mg kg^?1 hour^?1) (T-TIVA), while breathing 60% oxygen (FIO₂). The circumference changes of the rib cage (RC) and abdominal compartment (ABD) were recorded using respiratory ultrasonic plethysmography (RUP). Balloon tipped catheters were placed in the distal oesophagus and the stomach and maximal transdiaphragmatic pressure (P_{di max)} was calculated during Mueller's manoeuvre.ResultsThe breathing pattern T-ISO was more regular and respiratory rate significantly lower compared with T-TIVA. Ponies in T-TIVA showed regularly appearing sighs, which were never observed in T-ISO. Different contribution of the RC and ABD compartments to the breathing pattern was observed with a smaller participation of the RC to the total volume change during T-ISO. Transdiaphragmatic pressures (mean 13.7 ± SD 8.61 versus 23.4 ± 7.27 cmH₂O, p < 0.0001) were higher in T-TIVA compared to T-ISO. The sum of the RC and ABD circumferential changes was lower during T-TIVA compared to T-ISO (6.32 ± 4.42 versus 11.72 ± 4.38 units, p < 0.0001).Conclusion and clinical relevanceMarked differences in breathing pattern and transdiaphragmatic pressure exist during inhalation- and TIVA and these should be taken into account for clinical estimation of anaesthetic depth.     

Indirect measurement of blood pressure using a pulse oximeter in isoflurane anesthetized dogs

Objective: To determine the accuracy of indirect blood pressure (BP) measurements obtained with a pulse oximeter as compared with direct measurements in dogs under isoflurane anesthesia. The Doppler and oscillometric BP monitors were included for comparison. Design: Prospective, experimental study. Animals: Twenty healthy dogs (23 ± 8 kg) anesthetized for research or teaching. Interventions: Dogs were anesthetized with propofol or thiopental and maintained using positive pressure ventilation with isoflurane in 100% O₂. Random adjustment of BP was achieved by inhalant adjustment or dopamine infusion to achieve low (≤85 mmHg), normal (90–120 mmHg), or high systolic BP (≥125 mmHg). Triplicate measurements for BP were taken with direct (dorsal pedal artery), Doppler (forelimb), oscillometric (same forelimb), and plethysmographic (pulse oximeter on tongue) methods. Measurements and main results: Using regression analysis and a modified Bland–Altman's technique, the lowest bias was achieved with the Doppler. Systolic BP readings at low, normal, and high BP were within 10 mmHg of direct recordings 95%, 70%, and 30% of the time for pulse oximetry; 95%, 85%, and 55% of the time for Doppler; 42%, 65%, and 30% of the time for oscillometric determination, respectively. Oscillometric mean BP readings were within 10 mmHg of direct measurements 53%, 60%, and 45% of the time, respectively. Conclusions: The pulse oximeter is an acceptable method for measuring BP in anesthetized dogs if assessment of trends is sufficient. All indirect methods showed greater bias and poorer precision at high BP. The Doppler may be the preferred indirect method.     

A clinical comparison between a non‐invasive blood pressure monitor using high definition oscillometry (Memodiagnostic MD 15/90 Pro) and invasive arterial blood pressure measurement in anaesthetized dogs

ObjectiveTo compare high definition oscillometry (HDO) to invasive blood pressure measurement in anaesthetized dogs.Study designProspective, clinical trial.AnimalsFifty dogs weighing 1.95–79 kg (mean 23.5 kg).Materials and methodsAnaesthetic and peri–anaesthetic management was chosen according to each dog's physical status and anaesthetist's preference. Direct arterial blood pressure measurements were performed using a catheter placed in the dorsal pedal artery and an electronic pressure transducer connected to a multiparameter monitor. Non–invasive blood pressure measurements were performed using an appropriately sized cuff placed around the tail base. Comparisons between the two methods were made using Bland and Altman plots. The data are reported as mean bias (lower, upper limits of agreement). Further analysis was performed after separating the data into the following categories based on invasive mean arterial blood pressure (MAP): high (MAP > 100 mmHg), medium (70 mmHg < MAP < 100 mmHg) and low (MAP < 70 mmHg) blood pressure (BP). The two methods were compared as used clinically.ResultsEight hundred measurement pairs for invasive and HDO BP readings were compared. Overall, the HDO measured lower values for SAP and DAP but higher for MAP than the invasive method. The lowest bias (upper, lower limits of agreement) were obtained for MAP, ?1 (?22, 19) mmHg. The biggest discrepancy between the methods was reflected by a large bias (limits of agreement) 5 (?34, 45) mmHg, was for SAP. The results for DAP were between those for SAP and MAP with a bias (limits of agreement) of 3 (?20, 27) mmHg. When the values were separated into the pressure range categories the HDO measured higher in the high, medium and low BP groups, with the exception of SAP in the low BP group.ConclusionsWhen considering the mean bias, the accuracy of HDO compared well with direct arterial blood pressure, but the precision was poor, as determined by wide limits of agreement.Clinical relevanceUsing trends and serial measurements rather than a single measurement for clinical decision making is recommended with both methods, when used as reported here.     

Indirect oscillometric and direct blood pressure measurements in anesthetized and conscious neonatal foals

Objective: To investigate the agreement between indirect oscillometric and direct blood pressure measurement in the equine neonate. Design: Prospective observational study. Setting: University Veterinary Teaching Hospital. Animals: Ten crossbred foals of 30–46 hours of age. Interventions: Six animals (Group 1) were anesthetized. Four animals (Group 2) were restrained on a mat. All animals were instrumented with a catheter in the greater metatarsal artery and an oscillometric blood pressure cuff over the coccygeal artery. Blood pressure was varied with dobutamine, phenylephrine, nitroprusside, and increased depth of anesthesia (Group 1) or dopamine (Group 2). Measurements and main results: Simultaneous direct and indirect blood pressure measurements were obtained from the greater metatarsal artery and the coccygeal artery, respectively. There was good agreement between the 2 methods for mean and diastolic blood pressures in both groups, but not for systolic pressure. The agreement was best in mean blood pressure of anesthetized foals (mean bias –1.07; limits of agreement – 9.39, 7.25 mmHg). Conclusions: Indirect oscillometry appears to be an acceptable method for measuring mean arterial blood pressure in both anesthetized and conscious neonatal foals, and may be a valid method of monitoring critically ill foals.     

Agreement between invasive and oscillometric arterial blood pressure measurement using a high-definition oscillometric device in normotensive New Zealand White rabbits using two different anaesthetic protocols

ObjectiveTo use American College of Veterinary Internal Medicine (ACVIM) criteria to evaluate a high-definition oscillometric (HDO) blood pressure monitoring device versus invasive blood pressure (IBP) measurement in normotensive rabbits anaesthetized with two different anaesthetic protocols.Study designProspective experimental study.AnimalsA group of 20 healthy adult New Zealand White rabbits weighing 4.36 ± 0.37 kg (mean ± standard deviation).Materials and methodsRabbits were premedicated with butorphanol 0.5 mg kg^–1 and midazolam 0.5 mg kg^–1 subcutaneously (SC, group BMA) or ketamine 25 mg kg^–1 and medetomidine 0.4 mg kg^–1 SC (group KM). Anaesthesia was induced with alfaxalone administered intravenously (group BMA) or isoflurane by face mask (group KM) and maintained with isoflurane in oxygen. IBP was measured from the central auricular artery. The cuff for the HDO monitor was placed distal to the left elbow and distal to the left tarsus. Agreement between invasive and HDO measurements was evaluated using Bland–Altman method.ResultsIn group KM there was better agreement between the HDO device and IBP when the cuff was placed on the thoracic limb, with 100% and 91% of the readings for mean (MAP) and diastolic arterial pressure (DAP), respectively, within 10 mmHg of the IBP measurements. The agreement, although worse, also met the ACVIM criteria for systolic arterial pressure (SAP; 53% of the readings within 10 mmHg). In group BMA, the device met the criteria with the cuff on the thoracic limb only, and only for MAP and DAP (73% and 75% of the measurements within 10 mmHg of the IBP, respectively) but not for SAP (12%).Conclusion and clinical relevanceThe HDO device met most of the ACVIM criteria for noninvasive blood pressure measurement in anaesthetized rabbits, specifically when the cuff was placed distal to the elbow and the anaesthetic protocol included ketamine and medetomidine.     

Comparison of the arterial blood gas,arterial oxyhaemoglobin saturation and end-tidal carbon dioxide tension during sevoflurane or isoflurane anaesthesia in rabbits

The effects of sevoflurane or isoflurane on arterial blood gas, arterial oxyhaemoglobin saturation and end-tidal CO2 tension were monitored during induction and maintenance of anaesthesia in 10 premedicated New Zealand White (NZW) rabbits.For induction, the anaesthetic agents were delivered via a face-mask. After induction was completed, an endotracheal tube was introduced for maintenance of anaesthesia for a period of 90 minutes. Changes in heart rate, respiratory rate, arterial blood gas, arterial oxyhaemoglobin saturation, blood pH and end-tidal CO2 tension were recorded. Although sevoflurane and isoflurane produce similar cardiopulmonary effects in premedicated rabbits, sevoflurane provides a smoother and faster induction because of its lower blood/gas partition coefficient. Thus sevoflurane is probably a more suitable agent than isoflurane for mask induction and maintenance. Its lower blood solubility also makes sevoflurane more satisfactory than isoflurane for maintenance of anaesthesia because it allows the anaesthetist to change the depth of anaesthesia more rapidly.     

Effects of cuff size and position on the agreement between arterial blood pressure measured by Doppler ultrasound and through a dorsal pedal artery catheter in anesthetized cats

ObjectiveTo compare the effects of cuff size/position on the agreement between arterial blood pressure measured by Doppler ultrasound (ABP_Doppler) and dorsal pedal artery catheter measurements of systolic (SAP_invasive) and mean arterial pressure (MAP_invasive) in anesthetized cats.Study designProspective study.AnimalsA total of eight cats (3.0–3.8 kg) for neutering.MethodsDuring isoflurane anesthesia, before surgery, changes in end-tidal isoflurane concentrations and/or administration of dopamine were performed to achieve SAP_invasive within 60–150 mmHg. Cuff sizes 1, 2 and 3 (bladder width: 20, 25 and 35 mm, respectively) were placed on distal third of the antebrachium, above the tarsus and below the tarsus for ABP_Doppler measurements. Agreement between ABP_Doppler and SAP_invasive or between ABP_Doppler and MAP_invasive was compared with reference standards for noninvasive blood pressure devices used in humans and small animals.ResultsMean bias and precision (±standard deviation) between ABP_Doppler and SAP_invasive met veterinary standards (≤10 ± 15 mmHg), but not human standards (≤5 ± 8 mmHg), with cuffs 1 and 2 placed on the thoracic limb (7.4 ± 13.9 and –5.8 ± 9.5 mmHg, respectively), and with cuff 2 placed proximal to the tarsus (7.2 ± 12.4 mmHg). Cuff width-to-limb circumference ratios resulting in acceptable agreement between ABP_Doppler and SAP_invasive were 0.31 ± 0.04 (cuff 1) and 0.42 ± 0.05 (cuff 2) on the thoracic limb, and 0.43 ± 0.05 (cuff 2) above the tarsus. ABP_Doppler showed no acceptable agreement with MAP_invasive by any reference standard.Conclusions and clinical relevanceThe agreement between ABP_Doppler and SAP_invasive can be optimized by placing the occlusive cuff on the distal third of the antebrachium and above the tarsus. In these locations, cuff width should approach 40% of limb circumference to provide clinically acceptable estimations of SAP_invasive. Doppler ultrasound cannot be used to estimate MAP_invasive in cats.     

Validation of oscillometric blood pressure measurement using a Datex S/5 Compact multiparameter monitor in anaesthetized adult dogs

ObjectiveTo compare noninvasive (NIBP) with invasive blood pressure (IBP) measurements from a Datex S/5 Compact monitor in anaesthetized adult dogs, and to evaluate it according to the American College of Veterinary Internal Medicine (ACVIM) and the Association for the Advancement of Medical Instrumentation (AAMI) criteria.Study designProspective clinical study.AnimalsA group of 34 client-owned adult dogs.MethodsDogs were anaesthetized for different surgical procedures using different anaesthetic protocols. IBP was measured using a catheter placed in a dorsal pedal artery. A blood pressure cuff was placed over the contralateral dorsal pedal artery for NIBP measurement. Data were recorded using the Datex iCollect program, and paired readings were matched every 3 minutes for 60 minutes. Bland-Altman and error grid analyses were used to estimate the agreement between IBP and NIBP measurements, and its clinical significance, respectively. Data were reported as mean bias [lower, upper limits of agreement (LoA)].ResultsThe Datex S/5 monitor conformed to most ACVIM criteria. The correlation coefficient was less than 0.9 for systolic, diastolic, and mean arterial pressures (MAP). The best agreement between the noninvasive and invasive methods was observed for MAP, with LoA (–17 to 13 mmHg) and higher percentage of NIBP readings within 5 (55.6%), 10 (81.7%) and 20 (98.6%) mmHg of the IBP values. The Datex S/5 NIBP technology did not meet the AAMI validation criteria and less than 95% of the paired measurements were found within the green zone of the error grid analysis.Conclusions and clinical relevanceThe Datex S/5 monitor conformed to most ACVIM criteria but not with the more rigorous AAMI standards. Despite good agreement between IBP and NIBP for MAP measurements, care must be taken when using this device to guide therapeutic interventions of blood pressure in anaesthetized healthy adult dogs.     

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 evaluation of the Surgivet V60046, a non invasive blood pressure monitor in anaesthetized dogs

OBJECTIVE: To compare the performance of the Surgivet Non-Invasive Blood Pressure (NIBP) monitor V60046 with an invasive blood pressure (IBP) technique in anaesthetized dogs. STUDY DESIGN: A prospective study. ANIMALS: Thirty-four dogs, anaesthetized for a variety of procedures. METHODS: Various anaesthetic protocols were used. Invasive blood pressure measurement was made using a catheter in the femoral or the pedal artery. A cuff was placed on the contralateral limb to allow non invasive measurements. Recordings of arterial blood pressures (ABPs) were taken at simultaneous times for a range of pressures. For analysis, three pressure levels were determined: high [systolic blood pressure (SAP) > 121 mmHg], normal (91 mmHg < SAP < 120 mmHg) and low (SAP < 90 mmHg). Comparisons between invasive and non invasive measurements were made using Bland-Altmann analysis. RESULTS: The NIBP monitor consistently underestimated blood pressure at all levels. The lowest biases and greatest precision were obtained at low and normal pressure levels for SAP and mean arterial pressure (MAP). At low blood pressure levels, the biases +/- 95% confidence interval (CI) were 1.9 +/- 2.96 mmHg (SAP), 8.3 +/- 2.41 mmHg diastolic arterial pressure (DAP) and 3.5 +/- 2.09 mmHg (MAP). At normal blood pressure levels, biases and CI were: 1.2 +/- 2.13 mmHg (SAP), 5.2 +/- 2.32 mmHg (DAP) and 2.1 +/- 1.54 mmHg (MAP). At high blood pressure levels, the biases and CI were 22.7 +/- 5.85 mmHg (SAP), 5.5 +/- 3.13 mmHg (DAP) and 9.4 +/- 3.52 mmHg (MAP). In 90.6% of cases of hypotension (MAP < 70 mmHg), the low blood pressure was correctly diagnosed by the Surgivet. CONCLUSIONS: Measurement of blood pressure with the indirect monitor allowed detection of hypotension using either SAP or MAP. The most accurate readings were determined for MAP at hypotensive and normal levels. The monitor lacked accuracy at high pressures. CLINICAL RELEVANCE: When severe challenges to the cardiovascular system are anticipated, an invasive method of recording ABP is preferable. For routine usage, the Surgivet monitor provided a reliable and safe method of NIBP monitoring in dogs, thereby contributing to the safety of anaesthesia by providing accurate information about the circulation.