Direct Blood Pressure Research Articles

Enfermeiros de Unidade de Terapia Intensiva adulto: avaliação sobre medida direta e indireta da pressão arterial

Estudo descritivo e de corte transversal que teve como objetivo avaliar e autoavaliar o conhecimento de enfermeiros de Unidades de Terapia Intensiva adulto sobre medida direta e indireta da pressão arterial. Foram abordados 54 enfermeiros de três Unidades de Terapia Intensiva. Foi aplicado um questionário auto respondido com 65 questões (40 relacionadas à pressão arterial). Os enfermeiros apresentaram desempenho insuficiente no teste que avaliou conhecimento (nota média 4,6). Metade da amostra sentiu-se pouco satisfeita com relação ao que sabe sobre pressão arterial. Após responder o questionário os sujeitos autoavaliaram seu conhecimento como regular (48,2%), ruim (27,8%) e péssimo (9,3%), manifestando estarem conscientes em relação à importância do assunto para a prática. Os resultados do estudo mostram a necessidade de realização urgente de atividades de educação continuada para esta amostra, visto que são profissionais que atuam diretamente com um sinal vital prioritário no cuidado ao paciente crítico.

Renal Replacement Therapy in Healthy Adult Horses

Renal replacement therapy (RRT) has been implemented extensively in people to facilitate recovery from acute renal failure (ARF). RRT has not been explored in horses, but might provide a further treatment option in horses with ARF. To investigate efficacy and safety of RRT in horses. Five healthy adult horses. A prospective study was performed on horses restrained in stocks and intravenously connected to a commercial RRT machine to allow continuous venovenous hemodiafiltration to be performed for 6hours. The RRT machine was set at the following flow rates: blood flow rate 250mL/min; dialysate rate 3,000mL/h; prefilter replacement pump 3,000mL/h; and postfilter replacement pump rate 2,000mL/h. Balanced electrolyte solution was used as dialysate and replacement fluid. Heart rate, respiratory rate, body temperature, direct arterial blood pressure, urine output, and various clinicopathologic parameters were measured over the study period. Renal replacement therapy was successfully performed in horses, resulting in a mean creatinine clearance of 0.127mL/kg/min (68.9mL/min) and urea reduction ratio of 24%. No adverse effects were detected although a significant decrease in rectal temperature was observed (P≤.007). A significant increase in serum phosphorus (P≤.001) and decrease in BUN (P<.001) were also noted. A significant prolongation of prothrombin (P<.01) and partial thromboplastin time (P<.0001) were observed along with a decrease in platelet count (P≤.04). Renal replacement therapy can safely and effectively be used in adult horses.

Near real-time notification of gaps in cuff blood pressure recordings for improved patient monitoring

Blood pressure monitoring during anesthesia is an American Society of Anesthesiology standard. However, the anesthesia provider sometimes fails to engage the patient monitor to make periodic (generally every 3-5 min) measurements of Non-Invasive Blood Pressure (NIBP), which can lead to extended periods (>5 min) when blood pressure is not monitored. We describe a system to automatically detect such gaps in NIBP measurement and notify clinicians in real-time to initiate measurement. We applied a decision support system called the Smart Anesthesia Messenger (SAM) to notify the anesthesia provider if NIBP measurements have not been made in the last 7 min. Notification messages were generated only if direct arterial blood pressure was not being monitored. NIBP gaps were analyzed for 9 months before and after SAM notification was initiated (12,000 cases for each period). SAM notification was able to reduce the occurrence of extended NIBP gaps >15 min from 15.7 ± 4.5 to 6.7 ± 2.0 instances per 1,000 cases (p < 0.001). In addition, for extended gaps (>15 min) the mean gap duration declined from 23.1 ± 2.0 to 18.6 ± 1.1 min after SAM notification was initiated (p < 0.001). However, for 7-15 min gaps, SAM notification was not effective in reducing the occurrence. The maximum gap encountered before SAM was 64 min, while it was 27 min with SAM notification. Real-time notification using SAM is an effective way to reduce both the number of instances and the duration of inadvertent, extended (>15 min) gaps in blood pressure measurements in the operating room. However, the frequency of gaps <15 min could not be reduced using the current configuration of SAM.

The effects of unripe grape extract on systemic blood pressure, nitric oxide production, and response to angiotensin II administration

Background:Hypertension is the most common disease in the world. In Iranian folk medicine, unripe grape juice has been used as antihypertention remedy, but no data is documented for this popular belief. This study was designed to determine the effect of unripe grape extract (UGE) on blood pressure and the response to angiotensin II in rat.Materials and Methods:Unripe grape was collected, air dried, and extracted and concentrated. Four groups of Wistar rats received single doses of 125, 250, and 500 mg/kg of UGE or saline, respectively. The direct blood pressure and the serum nitrite level were measured one hour post UGE administration. The animals also were subjected to the infusion of various angiotensin II concentrations (100, 300, and 1000 μg/kg/min), and blood pressure was determined.Results:Mean arterial, systolic, and diastolic pressures (MAP, SP, and DP) in all UGE treated groups were less than the control group, but only at the dose of 125 mg/kg (Group 1) they were significantly different (P < 0.05). The level of nitrite in groups 1-3 were significantly greater than the control group (P < 0.05). No significant differences were detected for the MAP, SP, and DP to different concentrations of angiotensin II among these groups.Conclusion:UGE potentially attenuate MAP, SP, and DP via vasodilatation induced by nitric oxide production.

Comparison of Direct vs. Indirect Blood Pressure Measurements on Treadmill and Bicycle in Hypertensive Responders

Objectives: This study tested whether the systolic and diastolic blood pressures measured simultaneously by direct and indirect methods provide similar readings for blood pressure response during symptom-limited exercise on a treadmill and bicycle, and if it can be used to monitor blood pressure in hypertensive patients treated with β- blockers. Method: Comparisons were made with simultaneously determined intra-arterial catheter and auscultation measurements on a treadmill and bicycle. Eight hypertensive patients (41.9 ± 2.0 years) active participants in supervised aerobic programs (12.1 ± 1.2 METs work capacity) for at least 12 months were recruited to the study. Results: At rest, indirect systolic pressure was highly correlated with the direct method (r=0.85), with mean of 139 ± 7 and 134 ± 6 mmHg, respectively, at peak treadmill exercise (r=0.90), with mean of 198 ± 11 and 189 ± 9 and bicycle (r=0.92) with mean of 204 ± 10 196±9 mmHg respectively. Indirect diastolic blood pressure correlates well with intra-arterial at rest (r=0.82), with mean of 96 ± 11 and 88 ± 9 mmHg, respectively. However, at peak treadmill exercise, the correlation coefficient between the direct and the indirect methods was low (r=0.40), with mean of 105 ± 9 and 112 ± 12 mmHg, respectively. At peak bicycle exercise correlation was (r=0.58) with mean of 107 ± 9 and 112 ± 12 mmHg. Conclusions: These results suggest that at peak treadmill exercise and bicycle, the indirect method tends to bias low compared with direct therefore it is not valid for the assessment of diastolic pressure in hypertensive patients. Intensity should be considered when using cardiovascular variables as outcome measures.

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

This study was performed to evaluate three different noninvasive blood pressure measurement methods (NIBP) in comparison with direct blood pressure measurements in anesthetized dogs. Ten normal healthy Beagle dogs (mean age; 3.7 ± 1.01 yrs, mean body weight 10.2 ± 1.15 kg) were enrolled in this study. The BP was measured by three different methods, i.e., Doppler (DOP), oscillometric and high density oscillometric (HDO), simultaneously for 5 times in each subject under anesthesia at three different locations (right, left front legs and tail). The blood pressure value measured by Doppler method was the most close to the value measured by the direct method. Although the accuracy and consistency of the BP measured by 3 different non-invasive methods were differed by the method, all methods except conventional oscillometric method were acceptable for monitoring systolic blood pressure in anesthetic dogs and the inter-measurement variations in DOP and HDO was minimal enough not to affect the consistency of test result.

Serum Asymmetric Dimethylarginine Concentrations in Two Models of Experimentally Induced Hypertension

The aim of this study was to evaluate the effect of two models of hypertension on serum ADMA concentrations and whether the changes of serum ADMA concentrations are reversible by removing the cause of hypertension.Materials and Methods. 48 male wistar rats were randomly assigned into four groups: control, deoxycorticosterone acetate salt (DOCA-Salt), sham, and two kidneys one clip (2K1C). After 12 weeks, in half of the animals (n=6each group), serums were taken and direct blood pressure was measured. Then, DOCA injection was withdrawn and the animals received tap water and, in 2K1C group, renal clips were removed. After 12 weeks, direct blood pressure was measured and blood samples were taken.Results. Serum ADMA concentration in DOCA-Salt group was slightly higher than control, although it was not statistically significant. In 2K1C hypertensive group, serum ADMA concentration was significantly elevated compared to sham group (P&lt;0.05). Unclipping and reversal of hypertension returned serum ADMA level to sham group. There was a weak positive correlation between systolic blood pressure and serum ADMA concentration.Conclusion. increased serum ADMA concentration during hypertension is dependent on the model of hypertension, and removing the cause of hypertension could reduce it

Relation Between Blood Pressure Estimated by Pulse Wave Velocity and Directly Measured Arterial Pressure

Hypertension is the strongest risk factor in cardiac and cerebrovascular diseases among the Japanese. Even daily variations in blood pressure may become a risk, and repeated blood pressure measurement is recommended. Conventional Ambulatory Blood Pressure Monitoring (ABPM), however,may cause discomfort to examinees because they have to have their arms compressed and carry the monitor itself. The number of ABPMmeasurements is limited to about 1 every 15–30 minutes. We therefore attempted, working with medical and engineering teams, to develop a wearable blood pressure sensor that would place less burden on examinees, be less influenced by physical movement, and be usable for continuous blood pressure measurement. We then examined the clinical practicality of the sensor. We modified the existing Moens-Korteweg blood-pressure equation and developed a new systolic blood pressure calculation system that used electrocardiography and ear-lobe pulse waves because the ear lobe would receive little influence from physical movement. We chose three clinical cases from among intensive care unit subjects. We not only estimated their blood pressure using the systemwe developed but also measured arterial pressure directly with an intravascular catheter to see how estimated blood pressure followed actual changes in blood pressure and to evaluate the accuracy of estimated blood pressure. When systolic blood pressure estimated by using the pulse wave velocity method was compared with direct blood pressure measurement, we found that the method captured trends in blood pressure variations correctly. The difference was within ±10 mmHgfor all of the cases. In a comparison using the Bland-Altman method for the three clinical cases, the average difference was –0.4 mmHg, –1.0 mmHg, and –1.7 mmHg and standard deviation was 4.2 mmHg, 4.8 mmHg, and 4.3 mmHg, respectively, which indicated good agreement. Introducing such wearable blood pressure sensors into daily medical practice gets detailed information on continuous blood pressure variation while examinees move freely and the resulting information is used for better quality control of adult diseases. It is also expected that wearable blood pressure sensors can be used in emergency medical cases, in intensive care, and at remote sites.

Alfaxalone and medetomidine intravenous infusion to maintain anaesthesia in colts undergoing field castration

The use of alfaxalone and medetomidine administered as an i.v. infusion to maintain anaesthesia has not previously been reported in the horse. To investigate the use of alfaxalone in hydroxpropyl-beta-cyclodextrin (Alfaxan) and medetomidine infusion as a field anaesthetic for short-term surgical procedures in the horse. Alfaxalone-medetomidine anaesthesia is suitable for short-term field anaesthesia in horses. Eleven healthy colts underwent 45 min of anaesthesia with an i.v. infusion of alfaxalone (2 mg/kg bwt/h) and medetomidine (5 μg/kg bwt/h) for routine field castration. Horses were premedicated with i.v. acepromazine (0.03 mg/kg bwt), medetomidine (7 μg/kg bwt) and guaiphenesin (35 mg/kg bwt) before i.v. induction with alfaxalone (1 mg/kg bwt). Colts were intubated with an endotracheal tube and 100% oxygen insufflated at 10 l/min. The physiological variables monitored included pulse rate, respiratory rate, direct arterial blood pressure, arterial blood gases and the quality of the inductions and recoveries were scored. Overall, the anaesthetic period and surgical conditions were acceptable and the quality of the anaesthetic inductions and recoveries was good to excellent. All colts stood on their first attempt (mean ± s.d.) 37 ± 13.5 min after the infusion was stopped. During anaesthesia, cardiopulmonary data, presented as range of mean values at each time point were: heart rate: 45-47 beats/min; mean blood pressure: 104-112 mmHg; respiratory rate: 8 breaths/min; PaO2 : 117-172 mmHg; PaCO2 : 50-56 mmHg and pH 7.34-7.37. The co-administration of alfaxalone and medetomidine as an i.v. infusion after anaesthetic induction with alfaxalone was suitable for short-term field anaesthesia in the horse.

Plasma pharmacokinetics and pharmacodynamics of alfaxalone in neonatal foals after an intravenous bolus of alfaxalone following premedication with butorphanol tartrate

ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroid anaesthetic, alfaxalone, in neonatal foals after a single intravenous (IV) injection of alfaxalone following premedication with butorphanol tartrate. Study designProspective experimental study. AnimalsFive clinically healthy Australian Stock Horse foals of mean ± SD age of 12 ± 3 days and weighing 67.3 ± 12.4 kg. MethodsFoals were premedicated with butorphanol (0.05 mg kg−1 IV) and anaesthesia was induced 10 minutes later by IV injection with alfaxalone 3 mg kg−1. Cardiorespiratory variables (pulse rate, respiratory rate, direct arterial blood pressure, arterial blood gases) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and alfaxalone plasma concentrations were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. ResultsThe harmonic, mean ± SD plasma elimination half life (t½) for alfaxalone was 22.8 ± 5.2 minutes. The observed mean plasma clearance (Clp) and volume of distribution (Vd) were 19.9 ± 5.9 mL minute kg−1 and 0.6 ± 0.2 L kg−1, respectively. Overall, the quality of the anaesthetic inductions and recoveries was good and most monitored physiological variables were clinically acceptable in all foals, although some foals became hypoxaemic for a short period following recumbency. The mean durations of anaesthesia from induction to first movement and from induction to standing were 18.7 ± 7 and 37.2 ± 4.7 minutes, respectively. ConclusionsThe anaesthetic protocol used provided a predictable and consistent plane of anaesthesia in the five foals studied, with minimal cardiovascular depression. In foals, as in the adult horse, alfaxalone has a short elimination half life. Clinical relevanceAlfaxalone appears to be an adequate anaesthetic induction agent in foals and the pharmacokinetics suggest that, with continuous infusion, it might be suitable to provide more prolonged anaesthesia. Oxygen supplementation is recommended.

Mercury exposure and risk of hypertension in US men and women in 2 prospective cohorts.

Cross-sectional studies and animal experiments suggest that methylmercury exposure could increase the risk of hypertension. This relationship has not been evaluated in large prospective studies. Using data from previous nested case-control studies in 2 separate prospective cohorts, we measured toenail mercury, a valid biomarker of long-term methylmercury exposure, among 6045 US men and women free of hypertension at baseline. Geometric mean toenail mercury concentrations were 0.08 μg/g in the lowest quintile and 0.74 μg/g in the highest quintile, the latter corresponding with exposures ≈2.0-fold higher than the US Environmental Protection Agency reference dose. Participants were followed prospectively (mean±SD follow-up, 14.9±7.9 years) for a new self-report of physician-diagnosed hypertension (3540 cases), shown to be >95% sensitive and specific for diagnosing hypertension in these cohorts as compared with review of medical charts and direct blood pressure measurement, respectively. After adjustment for demographic, clinical, and lifestyle risk factors, the hazard ratio (95% CI) for incident hypertension in the highest versus lowest quintile of mercury exposure was 0.96 (0.84-1.09) in women, 0.82 (0.62-1.08) in men, and 0.94 (0.84-1.06) in both cohorts combined. Findings were similar when more extreme categories of mercury were compared (across deciles, with geometric mean levels in highest decile ≈2.9-fold higher than the reference dose) and in analyses stratified by fish or omega-3 consumption, selenium levels, body mass index, and age. These findings from 2 separate large prospective cohort studies do not support any clinically apparent adverse effects of methylmercury exposure on the risk of hypertension in men or women, including at levels ≤2.5-fold higher than the reference dose.

CARDIOVASCULAR EFFECTS OF VASOACTIVE SUBSTANCES IN PROLONGED ANESTHESIA IN DOGS

Knowledge of the influence of anesthesia in anesthetized animals at in vivo experiments is essential in order to interpret the results of investigations properly and correctly. In this study we researched cardiovascular effects of vasoactive substances (adrenalin, noepinephrine, dimethylphenylpiperazinium, acethylholin, histamine) in prolonged anesthesia of six hours in dogs. The cardiovascular effects of vasoactive substances were evaluated by direct blood pressure measurement, ecg monitoring and urine output measurement. The dose-effect curve of systolic (SAP) and diastolic (DAP) blood pressure were obtained for each of the vasoactive substances. The differences between cardiovascular effects of vasoactive substances at the beginning and at the end of prolonged anesthesia were tested. There were statistically significant differences (p&lt;0.05) in changes of blood pressure at the beginning and at the end of prolonged anesthesia only for some doses of adrenalin and histamine (1 mg/kg and 3 mg/kg). No significant changes in heart rhythms at the beginning and at the end of prolonged anesthesia were recorded. The urine output during anesthesia depended on applied vasoactive substances.

Direct intra‐abdominal pressures and abdominal perfusion pressures in unsedated normal horses

AbstractObjectivesTo determine whether direct intra‐abdominal pressures (IAP) and calculated direct abdominal perfusion pressures (APP) are location dependent within the abdomen of standing horses. We hypothesize that IAP will be increased and calculated APP will be decreased at a ventral abdominal location (V) when compared to values obtained from the left (LFl) or right flank (RFl).DesignProspective experimental design.SettingUniversity‐based equine research facility.AnimalsSeven healthy adult horses, 4 geldings and 3 mares.InterventionsMeasurements of direct IAP obtained from the RFl, LFl, and V locations via abdominal cannulation and direct arterial blood pressures obtained via catheterization of the transverse facial artery were obtained in fasted, standing, unsedated horses. APP was calculated for each location by the subtraction of IAP from the mean arterial pressure. Differences between sites of measurement for IAP, APP, and their gradients were calculated and compared by ANOVA and t‐tests.Measurements and Main ResultsMean flank IAP measurements were subatmospheric and negative compared to ventral IAP values (LFl = –3 mm Hg, RFl = –5 mm Hg, V = 25 mm Hg; P &lt; 0.001 between each flank and the ventral location). Ventrum APP was lower than flank APP (V = 82 mm Hg; LFl = 106 mm Hg; RFl = 108 mm Hg; P = 0.029 between each flank and the ventral location). Gradient calculations between sites showed the IAP increased and APP decreased from dorsal to ventral (P &lt; 0.05) and from right to left (P = 0.004) within the abdomen.ConclusionsIAP and calculated APP are location dependent. These data provide new information regarding abdominal pressure profiles in standing healthy adult horses.

Agreement between direct, oscillometric and Doppler ultrasound blood pressures using three different cuff positions in anesthetized dogs

ObjectiveTo evaluate the agreement between invasive blood pressure (IBP) and Doppler ultrasound blood pressure (DUBP) using three cuff positions and oscillometric blood pressure (OBP) in anesthetized dogs. Study designProspective study. AnimalsNine adult dogs weighing 14.5–29.5 kg. MethodsThe cuff was placed above and below the tarsus, and above the carpus with the DUBP and above the carpus with the OBP monitor. Based on IBP recorded via a dorsal pedal artery catheter, conditions of low, normal, and high systolic arterial pressures [SAP (mmHg) <90, between 90 and 140, and >140, respectively] were induced by changes in isoflurane concentrations and/or dopamine administration. Mean biases ± 2 SD (limits of agreement) were determined. ResultsAt high blood pressures, regardless of cuff position, SAP determinations with the DUBP underestimated invasive SAP values by more than 20 mmHg in most instances. With the DUBP, cuff placement above the tarsus yielded better agreement with invasive SAP during low blood pressures (0.2 ± 16 mmHg). The OBP underestimated SAP during high blood pressures (−42 ± 42 mmHg) and yielded better agreement with IBP for mean (MAP) and diastolic (DAP) arterial pressure measurements [overall bias: 2 ± 15 mmHg (MAP) and 0.2 ± 16 mmHg (DAP)]. ConclusionsAgreement of SAP determinations with the DUBP is poor at SAP > 140 mmHg, regardless of cuff placement. Measurement error of the DUBP with the cuff placed above the tarsus is clinically acceptable during low blood pressures. Agreement of MAP and DAP measurements with this OBP monitor compared with IBP was clinically acceptable over a wide pressure range. Clinical relevanceWith the DUBP device, placing the cuff above the tarsus allows reasonable agreement with IBP obtained via dorsal pedal artery catheterization. Only MAP and DAP provide reasonable estimates of direct blood pressure with the OBP monitor evaluated.

Comparison of direct and Doppler arterial blood pressure measurements in rabbits during isoflurane anaesthesia

ObjectiveTo measure the level of agreement between Doppler measured (DOP) arterial blood pressure (ABP) in the forelimb and directly measured (DIR) auricular systolic ABP (SAP) and mean ABP (MAP) in isoflurane-anaesthetized rabbits. Study designProspective clinical study. AnimalsData were analysed from 17 of 24 healthy rabbits, weighing 1.3–2.8 kg. MethodsRabbits were anaesthetized for neutering using a standardized protocol. A 26G catheter placed in an auricular artery was connected via heparinised saline filled non-compliant tubing (regularly flushed) to a calibrated pressure transducer (zeroed level with the thoracic inlet) to obtain DIR ABP. A cuff was placed proximal to the carpus (approximately level with the thoracic inlet) and a Doppler transducer sited over the dorsal carpal branch of the radial artery to obtain DOP ABP. Simultaneous DIR and DOP ABP recordings were made every 5–10 minutes during anaesthesia. Agreement was assessed as described by Bland JM & Altman (2007). ResultsMean ± SD cuff width: limb circumference ratio was 0.50 ± 0.04. Mean between-method differences ± SD, DIR SAP- DOP and DIR MAP- DOP, were +1 ± 8 and −13 ± 8 mmHg respectively. The 95% limits of agreement between DIR SAP and DOP and between DIR MAP and DOP were −14 to +17 and −28 to +2 mmHg respectively. Differences between DIR SAP and DOP were ≤10 mmHg 85% of the time. Defining hypotension as either DIR SAP < 80 mmHg or DIR MAP < 60 mmHg, and taking DOP ABP of <80 mmHg to indicate hypotension, sensitivity and specificity were 92% and 67% respectively. ConclusionsGood agreement was found between DIR SAP and DOP. Doppler measurements below 80 mmHg are a reliable indicator of arterial hypotension. Clinical relevanceDOP is acceptable for monitoring ABP in isoflurane-anaesthetized rabbits and is useful for detection of hypotension.

Effects of Nifedipine on Cation Transport and Na - K-ATPase Activity in Erythrocytes and Electrolyte Homeostasis in Rats

Calcium channel antagonists have been reported to reduce blood pressure in those individuals at risk of cardiac and cerebrovascular events. There is no specific study available regarding the role of electrolyte alterations in blood pressure lowering effects of nifedipine. The present study was designed to investigate the role of electrolyte homeostasis, changes in ouabain-sensitive Na+ K+ adenosine triphosphatase (ATPase) activity, and net sodium efflux and potassium influx across blood cell membranes. Rats were divided into two experimental groups . Nifedipine (20mg/ kg body weight ) was administered by gastric tube to the test group . Control group received same volume of deionize water .The intra-erythrocyte sodium, serum sodium, potassium, calcium and sodium, calcium content of heart and kidney tissues were decreased significantly. Whereas, intra-erythrocyte potassium was slightly decreased or remained normal in nifedipine treated rats as compared to normal healthy rats. The Na - K - ATPase activity, serum magnesium, potassium and magnesium content in heart and kidney tissues were increased significantly. Results confirmed that nifedipine represses ion channels, transporters and calcium-binding proteins in tissues. Erythrocyte studies indicate that nifedipine blocks the entrance of calcium into the cells but also stimulate Na - K - ATPase activity, resulting in reduction of intracellular sodium concentration, thus suggesting direct nifedipine-induced blood pressure reduction.

Which pressure to believe? A comparison of direct arterial with indirect blood pressure measurement techniques in the pediatric intensive care unit

To determine the accuracy of arterial blood pressure monitoring using 1) direct arterial; 2) automated oscillometric; and 3) sphygmomanometer/Doppler ultrasound measurements in pediatric intensive care patients comparing methods 1) and 2) with 3), the gold standard used to define normal blood pressure. Prospective observational study. Pediatric intensive care unit of a tertiary care pediatric teaching hospital. Forty children (birth to 17 yrs) admitted to the pediatric intensive care unit with various clinical conditions requiring a radial arterial catheter for continuous arterial blood pressure monitoring. None. Each subject had measurements taken every 6 hrs over a 24-hr period. Each set of measurements were: direct arterial blood pressure, indirect blood pressure using the Phillips automated oscillometric device, and indirect blood pressure using the sphygmomanometer and Doppler ultrasound. Analysis used the Bland-Altman plot followed by paired t testing to compare the three different methods. One hundred sixty triads of measurements were analyzed. There were no significant differences between the methods of blood pressure measurement when groups were analyzed based on age. When analyzed by age-specific normo-, hypo-, and hypertensive criteria, arterial blood pressure measurements agree closely with Doppler ultrasound readings, whereas systolic arterial blood pressure measurements were lower than indirect blood pressure using the Phillips automated oscillometric device readings in the hypotensive group (p < .001). In the hypertensive group, the systolic arterial blood pressure values were higher and indirect blood pressure using the Phillips automated oscillometric device readings lower (p < .001) than Doppler ultrasound (p = .03). There was no clinically significant difference between methods in the normotensive group. Diastolic blood pressure measurements were higher by arterial blood pressure in normotensive and hypertensive groups but no different in the hypotensive group. Outside the normotensive range, the automated readings were higher during hypotension and lower during hypertension compared with the arterial and Doppler ultrasound methods. The arterial blood pressure was closer to the gold standard Doppler ultrasound blood pressure in all three blood pressure groups.

Evaluation of the isoflurane-sparing effects of lidocaine infusion during umbilical surgery in calves

ObjectiveTo evaluate the isoflurane-sparing effects of lidocaine administered by constant rate infusion (CRI) during umbilical surgery in calves. Study designRandomized ‘blinded’ prospective clinical study. AnimalsThirty calves (mean 4.7 ± SD 2.5 weeks old) undergoing umbilical surgery. MethodsAfter premedication with xylazine (0.1 mg kg−1, IM), anaesthesia was induced with ketamine (4 mg kg−1, IV) and maintained with isoflurane in O2 administered through a circle breathing system. The calves were assigned randomly to receive a bolus of 2 mg kg−1 lidocaine IV after induction of anaesthesia, followed by CRI of 50 μg kg−1 minute−1 (group L, n = 15) or a bolus and CRI of 0.9% sodium chloride (NaCl, group S, n = 15). End-tidal isoflurane was adjusted to achieve adequate depth of anaesthesia. Heart rate, direct arterial blood pressure and body temperature were measured intraoperatively. Groups were compared by t- tests, anova or Mann–Whitney rank sum test as appropriate. ResultsThe end-tidal concentration of isoflurane (median, IQR) was significantly lower in group L [1.0% (0.94–1.1)] compared to group S [1.2% (1.1–1.5)], indicating a 16.7% reduction in anaesthetic requirement during lidocaine CRI. Cardiopulmonary parameters and recovery times did not differ significantly between groups. Conclusion and clinical relevanceLidocaine CRI may be used as a supplement to inhalation anaesthesia during umbilical surgery in calves in countries where such a protocol would be within the legal requirements for veterinary use in food animals. This study did not show any measurable benefit to the calves other than a reduction in isoflurane requirement.

Case Scenario: Metastatic Pediatric Paraganglioma Presenting during the Course of an Elective Surgery

P HEOCHROMOCYTOMA and paraganglioma are neuroendocrine tumors rarely diagnosed in pediatric patients. The incidence of malignant pheochromocytoma and paraganglioma in childhood is approximately 0.02 cases per million every year. Coincidental intraoperative diagnosis of pheochromocytoma involves very high mortality rates, reaching 50%. We present a case of coincidental diagnosis of pediatric metastatic malignant paraganglioma during an elective surgical procedure. The evaluation and management of pheochromocytoma and paraganglioma are discussed.

Determination of cardiac output by ultrasound velocity dilution in normovolemia and hypovolemia in dogs

ObjectiveThe purpose of this study was to compare CO measured by use of lithium dilution (LiDCO) and ultrasound velocity dilution (UDCO) in a canine model of acute hemorrhage. Study designProspective descriptive evaluation. AnimalsTwelve dogs (15–34 kg). MethodsDogs were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases and CO. The CO was measured by use of LiDCO and UDCO techniques. Measurements were obtained from each animal at baseline and during a low CO state (hemorrhagic state). Measurements were converted to cardiac index (CI = CO/BSA) values for statistical analysis. To measure CO using UDCO, a 20 mL bolus of 0.9% sodium chloride was administered and CO was calculated from the transient dilution of blood proteins created by the injection bolus. Hypovolemia was induced by withdrawing 40% of the blood volume until the mean arterial blood pressure (MAP) was stable at 40 mmHg for 10 minutes. Agreement was determined using Bland & Altman analysis and concordance correlation coefficients. ResultsTwenty-four comparisons were made. Lithium determinations of CI ranged between 7.5 and 1.3 L minute−1 m−2, and the mean overall difference between the two methods was −0.40 L minute−1 m−2. The mean relative bias was −17 ± 21% (limits of agreements: −59% to 25%). There was no significant effect of state of CI on bias or relative bias (p = 0.24 and p = 0.10, respectively). The concordance correlation coefficient between LiDCO and UDCO as 0.88 (p < 0.0001). ConclusionsWhen compared to lithium dilution, the UDCO technique is a viable method for measuring cardiac output in a model of normovolemia and hypovolemia in dogs.