Systolic Arterial Pressure Measurements Research Articles

Predictive model for post-induction hypotension in patients undergoing transcatheter aortic valve implantation: a retrospective observational study

PurposePost-induction hypotension (PIH) is an independent risk factor for prolonged postoperative stay and hospital death. Patients undergoing transcatheter aortic valve implantation (TAVI) are prone to develop PIH. This study aimed to develop a predictive model for PIH in patients undergoing TAVI.MethodsThis single-center retrospective observational study included 163 patients who underwent TAVI. PIH was defined as at least one measurement of systolic arterial pressure <90 mmHg or at least one incident of norepinephrine infusion at a rate >6 µg/min from anesthetic induction until 20 min post-induction. Multivariate logistic regression analysis was performed to develop a predictive model for PIH in patients undergoing TAVI.ResultsIn total, 161 patients were analyzed. The prevalence of PIH was 57.8%. Multivariable logistic regression analysis showed that baseline mean arterial pressure ≥90 mmHg [adjusted odds ratio (aOR): 0.413, 95% confidence interval (95% CI): 0.193–0.887; p=0.023] and higher doses of fentanyl (per 1-µg/kg increase, aOR: 0.619, 95% CI: 0.418–0.915; p=0.016) and ketamine (per 1-mg/kg increase, aOR: 0.163, 95% CI: 0.062–0.430; p=0.002) for induction were significantly associated with lower risk of PIH. A higher dose of propofol (per 1-mg/kg increase, aOR: 3.240, 95% CI: 1.320–7.920; p=0.010) for induction was significantly associated with higher risk of PIH. The area under the curve (AUC) for this model was 0.802.ConclusionThe present study developed predictive models for PIH in patients who underwent TAVI. This model may be helpful for anesthesiologists in preventing PIH in patients undergoing TAVI.

The additive prognostic value of end-systolic pressure-volume relation by stress CMR in patients with known or suspected coronary artery disease.

The difference between rest and peak stress end-systolic pressure-volume relation (ΔESPVR) is an afterload-independent index of left ventricular (LV) contractility. We assessed the independent prognostic value of ΔESPVR index by dipyridamole stress-cardiovascular magnetic resonance (CMR) in patients with known/suspected coronary artery disease (CAD). We considered 196 consecutive patients (62.74 ± 10.66years, 49 females). Wall motion and perfusion abnormalities at rest and peak stress were analysed. Replacement myocardial fibrosis was detected by late gadolinium enhancement(LGE) technique. The ESPVR was evaluated at rest and peak stress from raw measurement of systolic arterial pressure and end-systolic volume by biplane Simpson's method. A reduced ΔESPVR index (≤ 0.02mmHg/mL/m2) was found in 88(44.9%) patients and it was associated with a lower LV ejection fraction(EF) and with a higher frequency of abnormal stress CMR and myocardial fibrosis. During a mean follow-up of 53.17 ± 28.21months, 50(25.5%) cardiac events were recorded: 5 cardiac deaths, 17 revascularizations, one myocardial infarction, 23 hospitalisations for heart failure or unstable angina, and 4 ventricular arrhythmias. According to Cox regression analysis, diabetes, family history, LVEF, abnormal stress CMR, myocardial fibrosis, and reduced ΔESPVR were significant univariate prognosticators. In the multivariate analysis the independent predictors were ΔESPVR index ≤ 0.02mmHg/mL/m2 (hazard ratio-HR = 2.58, P = 0.007), myocardial fibrosis (HR = 2.13, P = 0.036), and diabetes (HR = 2.33, P = 0.012). ΔESPVR index by stress-CMR was independently associated with cardiac outcomes in patients with known/suspected CAD, in addition to replacement myocardial fibrosis and diabetes. Thus, the assessment of ΔESPVR index may be included into the standard stress-CMR exam to further stratify the patients.

Doppler ultrasound is more accurate than pulse oximeter plethysmography in the measurement of systolic arterial pressure from the median caudal artery in anesthetized dogs.

To compare the accuracy of doppler ultrasound (DOP) and pulse oximeter plethysmography (POP) in the measurement of systolic arterial pressure (SAP) to invasive blood pressure (IBP) in anesthetized dogs. 40 client-owned healthy dogs > 10 kg. Dogs were anesthetized for surgical procedures in dorsal recumbency. Invasive blood pressure was measured from a dorsal pedal artery. DOP and POP device probes were placed over the median caudal artery with a flow-occluding cuff for noninvasive blood pressure measurement. Systolic arterial pressure measured by DOP, loss of pulse oximeter plethysmograph (POPL), and return of pulse oximeter plethysmograph (POPR) were compared to SAP measured by IBP. A linear mixed model was used to determine correlation. Bland-Altman analyses were performed to determine bias, SD, and limits of agreement. The accuracy of DOP and POP was compared to IBP across different tensive states. Conditional R2 values for DOP, POPL, and POPR versus IBP were 0.92, 0.85, and 0.87, respectively (all P < .001). The biases for DOP, POPL, and POPR compared to IBP were +7.6 ± 13.1, +3.9 ± 14.4, and +8.6 ± 15.2 mm Hg (bias ± SD), respectively. Limits of agreement (lower, upper) were (-18.1, +33.3), (-24.3, +32.1), and (-21.2, +38.4) mm Hg for DOP, POPL, and POPR, respectively. DOP and POP overestimated SAP during hypotension (SAP < 90 mm Hg), DOP to a lesser magnitude. DOP measured from the median caudal artery may be acceptable for SAP measurement in dorsally recumbent, healthy anesthetized dogs > 10 kg. POP was determined an unacceptable method.

Agreement between oscillometric and direct blood pressure measurements in anesthetized captive chimpanzees (Pan troglodytes).

To evaluate the level of agreement (LOA) between direct and oscillometric blood pressure (BP) measurements and the ability of oscillometric measurements to accurately detect hypotension in anesthetized chimpanzees (Pan troglodytes). 8 captive, adult chimpanzees. During prescheduled annual examinations, each chimpanzee underwent general anesthesia and patient monitoring for their examination, echocardiography for a concurrent study, and measurement of direct BP with the use of tibial artery catheterization and oscillometry with the use of a cuff placed around a brachium and a cuff placed around the second digit of the contralateral forelimb for the present study. Bland-Altman plots were generated to compare results for direct and oscillometric BP measurements. Mean bias and 95% LOAs were calculated for oscillometric measurements of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) for each cuff site. Sensitivity and specificity in detecting hypotension were also determined for each cuff site. There were 74 paired direct and brachial oscillometric measurements of each, SAP, MAP, and DAP and 66 paired direct and digit oscillometric measurements of each, SAP, MAP, and DAP. Only brachial oscillometric measurements of MAP had adequate sensitivity (78%) and specificity (95%) to accurately detect hypotension, and this technique also had the least mean bias (0.8 mm Hg; 95% LOA, -29 to 31 mm Hg). Results indicated that brachial oscillometric measurement of MAP provided reasonable agreement with tibial arterial direct MAP measurement and performed well in diagnosing hypotension in anesthetized chimpanzees.

Pressure-volume relationship by pharmacological stress cardiovascular magnetic resonance.

The variation between rest and peak stress end-systolic pressure-volume relation (ΔESPVR) is an index of myocardial contractility, easily obtained during routine stress echocardiography and never tested during dipyridamole stress-cardiac magnetic resonance (CMR). We assessed the ΔESPVR index in patients with known/suspected coronary artery disease (CAD) who underwent dipyridamole stress-CMR. One-hundred consecutive patients (24 females, 63.76 ± 10.17years) were considered. ESPVR index was evaluated at rest and stress from raw measurement of systolic arterial pressure and end-systolic volume by biplane Simpson's method. The ΔESPVR index showed a good inter-operator reproducibility. Mean ΔESPVR index was 0.48 ± 1.45mmHg/mL/m2. ΔESPVR index was significantly lower in males than in females. ΔESPVR index was not correlated to rest left ventricular end-diastolic volume index or ejection fraction. Forty-six of 85 patients had myocardial fibrosis detected by the late gadolinium enhancement technique and they showed significantly lower ΔESPVR values. An abnormal stress CMR was found in 25 patients and they showed significantly lower ΔESPVR values. During a mean follow-up of 56.34 ± 30.04months, 24 cardiovascular events occurred. At receiver-operating characteristic curve analysis, a ΔESPVR < 0.02mmHg/mL/m2 predicted the presence of future cardiac events with a sensitivity of 0.79 and a specificity of 0.68. The noninvasive assessment of the ΔESPVR index during a dipyridamole stress-CMR exam is feasible and reproducible. The ΔESPVR index was independent from rest LV dimensions and function and can be used for a comparative assessment of patients with different diseases. ΔESPVR indexby CMR can be a useful and simple marker for additional prognostic stratification.

Comparison of invasive and non-invasive blood pressure measurements in anesthetized female Dorset cross-bred lambs (Ovis aries)

The purpose of this study was to determine the level of agreement between invasive and noninvasive blood pressure measurements in anesthetized, non-surgically manipulated Dorset cross-bred lambs.Twelve healthy female Dorset cross-bred lambs, weighing 37.3 ± 7.4 kg (mean ± SD) underwent isoflurane anesthesia for simultaneous measurement of systolic arterial pressure (SAP), mean arterial pressure (MAP) and diastolic arterial pressure (DAP) from an invasive blood pressure source and a noninvasive oscillometric source (O-NIBP). The femoral artery was catheterized for invasive blood pressure measurements, while noninvasive blood pressure was measured from a cuff placed on the antebrachium. The Bland-Altman method was used to calculate agreement between SAP, MAP and DAP measurements.The bias ± SD between SAP, MAP and DAP measurements was 3.6 ± 12.0, 4.9 ± 9.1 mmHg and 4.1 ± 8.0, respectively. The 95% limits of agreement for SAP, MAP and DAP were − 19.9 to 27.1, −13.0 to 22.8 mmHg, and − 11.7 to 19.9, respectively.Overall, agreement was poor between femoral IBP and O-NIBP monitoring techniques in anesthetized Dorset cross-bred lambs, with O-NIBP underestimating the femoral IBP. Arterial blood pressure should be most accurately measured using an invasive blood pressure monitoring technique in lambs undergoing isoflurane anesthesia.

Non-invasive oscillometric versus invasive arterial blood pressure measurements in critically ill patients: A post hoc analysis of a prospective observational study.

The aim was to compare non-invasive blood pressure measurements with invasive blood pressure measurements in critically ill patients. Non-invasive blood pressure was measured via automated brachial cuff oscillometry, and simultaneously the radial arterial catheter-derived measurement was recorded as part of a prospective observational study. Measurements of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) were compared using Bland-Altman and error grid analyses. Paired measurements of blood pressure were available for 736 patients. Observed mean difference (±SD, 95% limits of agreement) between oscillometrically and invasively measured blood pressure was 0.8mmHg (±15.7 mmHg, -30.2 to 31.7mmHg) for SAP, -2.9mmHg (±11.0mmHg, -24.5 to 18.6mmHg) for DAP, and -1.0mmHg (±10.2mmHg, -21.0 to 18.9mmHg) for MAP. Error grid analysis showed that the proportions of measurements in risk zones A to E were 78.3%, 20.7%, 1.0%, 0%, and 0.1% for MAP. Non-invasive blood pressure measurements using brachial cuff oscillometry showed large limits of agreement compared to invasive measurements in critically ill patients. Error grid analysis showed that measurement differences between oscillometry and the arterial catheter would potentially have triggered at least low-risk treatment decisions in one in five patients.

1177 The additive prognostic value of end-systolic pressure-volume relation by CMR in patients with with known or suspected coronary artery disease

Abstract Background The variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. This index is easily obtained during routine stress echocardiography but can be derived also during a stress cardiovascular magnetic resonance (CMR) exam, that is the gold standard for the quantification of biventricular volumes. Purpose The aim of this study was to assess for the first time the prognostic value ofdelta rest-stress ESPVR (DESPVR) by dipyridamole stress-CMR in patients with known or suspected coronary artery disease (CAD). Methods One hundred and sixty-six consecutive patients (37 females, main age 61.96 ± 10.05 years) who underwent dipyridamole stress-CMR in a high volume CMR Laboratory were considered. Abnormal wall motion and perfusion at rest and after dipyridamole were analysed. Macroscopic myocardial fibrosis was detected by the late gadolinium enhancement (LGE) technique. The ESPVR was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson method. Results An abnormal stress CMR was found in 39 (23.5%) patients; 24 patients had a reversible stress perfusion defect in at least one myocardial segment and 15 a reversible stress perfusion defect plus worsening of stress wall motion in comparison with rest. Myocardial fibrosis was detected in 69 patients (41.6%). A DESPVR &amp;lt; 0.009 was detected in 74 patients (44.6%). During a median follow up of 55.51 months (IQ range 33.20 months), 54 patients (32.5%) experienced major cardiac events: 5 deaths, 2 ventricular arrhythmias, 18 coronary syndromes, and 29 heart failure hospitalization.Reversible perfusion deficit, DESPVR &amp;lt; 0.009, diabetes and family history were significant univariate prognosticators. In the multivariate analysisthe independent predictive factors were reversible perfusion deficit (hazard ratio-HR = 2.17, P = 0.010), DESPVR &amp;lt; 0.009 (HR = 1.92, P = 0.028) and diabetes (HR = 2.42, P = 0.004). The Kaplan–Meier curve for DESPVR is shown in Figure 1. The log-rank test revealed a significant difference (P = 0.003). Conclusions DESPRV assessed by CMR provides a prognostic stratification in patients with known or suspected coronary artery disease, in addition to that supplied by reversible perfusion deficit and diabetes. Abstract 1177 Figure 1

P5285Pressure-volume relationship by cardiovascular magnetic resonance: feasibility and clinical implications

Abstract Background The variation between rest and peak stress end-systolic pressure-volume relation (ESPVR; the Suga index) is easily obtained during routine stress echocardiography and has been established as a reasonably load-independent index of myocardial contractile performance that provides prognostic information above and beyond regional wall motion. Purpose This is the first study assessing the delta rest-stress ESPVR (DESPVR) by stress Cardiovascular Magnetic Resonance (CMR). Methods Eighty-five consecutive patients (19 females, main age 62.99±9.26 years) who underwent dipyridamole stress-CMR in a high volume CMR Laboratory were considered. The ESPVR was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson method. Results Mean ESPVR index at rest and peak stress was, respectively, 4.52±2.26 mmHg/mL/m2 and 4.62±2.32 mmHg/mL/m2 and mean DESPVR was 0.11±1.19 mmHg/mL/m2. DESPVR was not associated to age or sex. An inverse relationship between rest left ventricular end-diastolic volume index (LVEDVI) and both rest and peak ESPVR was present (R=-0.805 P&lt;0.0001 and R=-0.795 P&lt;0.0001, respectively), but it was absent when the DESPVR was considered (R=0.170 P=0.121). An abnormal stress CMR was found in 22 patients and the DESPVR was comparable between patients with normal and abnormal stress exam. During a median follow-up of 60.62 months (IQ range 36.78 months), 27 cardiovascular events occurred: 3 deaths, 1 ventricular arrhythmias, 9 coronary syndromes, 14 heart failure hospitalization. At receiver-operating characteristic (ROC) curve analysis, a DESPVR&lt;0.009 predicted the presence of future cardiac events with a sensitivity of 0.70 and a specificity of 0.64 (P=0.049). Conclusions We showed for the first time that dipyridamole stress CMR can be used for the assessment of DESPVR. DESPVR was shown to be independent from chamber size and, as a consequence, can be used for a comparative assessment of patients with different diseases. DESPVR by CMR can provide a prognostic stratification and the optimal cutoff for relevant events was 0.009.

Pressure-volume Relationship in the Stress-echocardiography Laboratory: Does (Left Ventricular End-diastolic) Size Matter?

Introduction and objectivesThe variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. Whether and to what extent it depends on end-diastolic volume remains unclear. The aim of this study was to assess the dependence of the delta rest-stress end-systolic pressure-volume relation on end-diastolic volume in patients with negative stress echo and all ranges of resting left ventricular function. MethodsWe analyzed interpretable data obtained in 891 patients (593 men, age 63 ± 12 years) with ejection fraction 47% ± 12%: 338 were normal or near-normal or hypertensive; 229 patients had coronary artery disease; and 324 patients had ischemic or nonischemic dilated cardiomyopathy. They were studied with exercise (n = 172), dipyridamole (n = 482) or dobutamine (n = 237) stress echocardiography. The end-systolic pressure-volume relation was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson rule 2-dimensional echocardiography. ResultsAbsolute values of delta rest-stress end-systolic pressure-volume relation were higher for exercise and dobutamine than for dipyridamole. In the overall population, an inverse relationship between end-systolic pressure-volume relation and end-diastolic volume was present at rest (r2 = 0.69, P < .001) and peak stress (r2 = 0.56, P < .001), but was absent if the delta rest-stress end-systolic pressure-volume relation was considered (r2 = 0.13). ConclusionsLeft ventricular end-diastolic volume does not affect the rest-stress changes in end-systolic pressure-volume relation in either normal or abnormal left ventricles during physical or pharmacological stress.

Relación presión/volumen en el laboratorio de ecocardiografía de estrés. ¿Cómo influye el tamaño del ventrículo izquierdo (dimensión diastólica del ventrículo izquierdo)?

Introduction and objectivesThe variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. Whether and to what extent it depends on end-diastolic volume remains unclear. The aim of this study was to assess the dependence of the delta rest-stress end-systolic pressure-volume relation on end-diastolic volume in patients with negative stress echo and all ranges of resting left ventricular function. MethodsWe analyzed interpretable data obtained in 891 patients (593 men, age 63 ± 12 years) with ejection fraction 47% ± 12%: 338 were normal or near-normal or hypertensive; 229 patients had coronary artery disease; and 324 patients had ischemic or nonischemic dilated cardiomyopathy. They were studied with exercise (n = 172), dipyridamole (n = 482) or dobutamine (n = 237) stress echocardiography. The end-systolic pressure-volume relation was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson rule 2-dimensional echocardiography. ResultsAbsolute values of delta rest-stress end-systolic pressure-volume relation were higher for exercise and dobutamine than for dipyridamole. In the overall population, an inverse relationship between end-systolic pressure-volume relation and end-diastolic volume was present at rest (r2 = 0.69, P < .001) and peak stress (r2 = 0.56, P < .001), but was absent if the delta rest-stress end-systolic pressure-volume relation was considered (r2 = 0.13). ConclusionsLeft ventricular end-diastolic volume does not affect the rest-stress changes in end-systolic pressure-volume relation in either normal or abnormal left ventricles during physical or pharmacological stress.Full English text available from:www.revespcardiol.org/en

Comparison of the Haemodynamic Effects of Three Different Methods at the Induction of Anaesthesia.

Haemodynamic variations are inevitable during induction of anaesthetic drugs. The present study investigates the haemodynamic variations of three different drugs (thiopental, propofol, and etomidate) used for induction of general anaesthesia together with fentanyl. In a randomized, double-blind study, 45 patients were assigned to one of three groups (n=15 each). Fentanyl 1 μg kg(-1) was injected over 60 sec followed by propofol 2 mg kg(-1) (Group P), thiopentone 6 mg kg(-1) (Group T), or etomidate 0.3 mg kg(-1) (Group E). Noninvasive measurements of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), and heart rate (HR) was performed on admittance, immediately before the induction of anaesthesia, and 1, 3, and 5 min thereafter. Cardiac output (CO) values were recorded before induction, immediately after the injection of the drug, and at 1 min after the intubation. In all groups, during the study period, SAP, DAP, MAP, and CO values decreased with respect to time before induction. Following the administration of the induction dose of propofol (Group P), a significantly greater decrease of systolic and diastolic blood pressure was observed with etomidate (Group E) or thiopentone (Group T). Decrease in CO was also more marked with propofol (Group P) than with etomidate (Group E) or thiopentone (Group T). It's concluded that, in this study, the combination of fentanyl-etomidate is safer than both the groups of fentanyl-propofol and fentanyl-thiopental in terms of providing haemodynamic stability.

Vitamin D induces increased systolic arterial pressure via vascular reactivity and mechanical properties.

Background/AimsThe aim of this study was to evaluate whether supplementation of high doses of cholecalciferol for two months in normotensive rats results in increased systolic arterial pressure and which are the mechanisms involved. Specifically, this study assesses the potential effect on cardiac output as well as the changes in aortic structure and functional properties.MethodsMale Wistar rats were divided into three groups: 1) Control group (C, n = 20), with no supplementation of vitamin D, 2) VD3 (n = 19), supplemented with 3,000 IU vitamin D/kg of chow; 3) VD10 (n = 21), supplemented with 10,000 IU vitamin D/kg of chow. After two months, echocardiographic analyses, measurements of systolic arterial pressure (SAP), vascular reactivity, reactive oxygen species (ROS) generation, mechanical properties, histological analysis and metalloproteinase-2 and -9 activity were performed.ResultsSAP was higher in VD3 and VD10 than in C rats (p = 0.001). Echocardiographic variables were not different among groups. Responses to phenylephrine in endothelium-denuded aortas was higher in VD3 compared to the C group (p = 0.041). Vascular relaxation induced by acetylcholine (p = 0.023) and sodium nitroprusside (p = 0.005) was impaired in both supplemented groups compared to the C group and apocynin treatment reversed impaired vasodilation. Collagen volume fraction (<0.001) and MMP-2 activity (p = 0.025) was higher in VD10 group compared to the VD3 group. Elastin volume fraction was lower in VD10 than in C and yield point was lower in VD3 than in C.ConclusionOur findings support the view that vitamin D supplementation increases arterial pressure in normotensive rats and this is associated with structural and functional vascular changes, modulated by NADPH oxidase, nitric oxide, and extracellular matrix components.

A comparison of epidural analgesia and local infiltration analgesia methods in pain control following total knee arthroplasty

The aim of this study was to compare the effects of epidural analgesia with infiltration analgesia in postoperative pain control for total knee arthroplasty. Thirty patients (28 female, 2 male; mean age: 69.37±5.11 years, range: 61 to 80 years) undergoing total knee arthroplasty between May 2011 and September 2011 were randomly divided into 2 groups. All patients received spinal anesthesia with bupivacaine. Postoperative analgesia of 72 ml 0.9% NaCl + 48 ml bupivacaine (1 ml = 5 mg, total 120 ml) was administered throughout 24 hours to Group 1 (n=15) by epidural catheter and to Group 2 (n=15) by ON-Q infiltration pump. Groups were compared based on the Bromage scores and visual analog scale (VAS), blood pressure, postoperative analgesia requirement and side effects. Demographic data were similar in both groups. Rates of additional analgesia requirement at the postoperative 60th minute and 2nd hour were significantly higher in Group 2 than Group 1 (p<0.05). Rates of nausea-vomiting at the postoperative 60th minute and 2nd hour were significantly higher in Group 1 than Group 2 (p<0.05 and p<0.01, respectively). Bromage scores at 60 minutes and 2 hours was significantly higher in Group 1 than in Group 2 (p<0.01). Mean VAS scores at 60 minutes and 2 hours were significantly higher in Group 2 than Group 1 (p<0.05). While a statistically significant difference was found between systolic arterial pressure measurements at 60 minutes (p<0.05), there was no significant difference in diastolic arterial pressure and peak heart rate. Although the analgesic effect of local infiltration is provided later than by epidural analgesia, the same level of pain control can be achieved with initial additional analgesia. Local infiltration is superior to epidural analgesia in respect of few side effects and early mobilization.

Comparison of high definition oscillometric and Doppler ultrasonic devices for measuring blood pressure in anaesthetised cats

Indirect blood pressure measurements using high definition oscillometric (HDO) and Doppler devices were compared in 50 anaesthetised client-owned cats presented for various surgical procedures. Sites of cuff placement for Doppler were identified as forelimb and hindlimb and for HDO as forelimb and tail. Oscillometric and Doppler readings were obtained in 90.05% and 100% of attempts, respectively. Both devices enabled precise measurement of systolic arterial pressure (SAP), although the Doppler device gave higher precision. In the low pressure group (SAP<100 mmHg; n=30), 66.7% biases were within 10 mmHg of discrepancy, but in groups of normal (100 mmHg ≤ SAP ≤ 150 mmHg; n=120) and high measurements (SAP>150 mmHg; n=62), 86.7% and 75.0% of discrepancy, respectively, were lower than 10 mmHg. Frequency of discrepancy at the range of 15 mmHg showed similar differences between pressure groups. There were significantly higher discrepancies when the cuff was positioned on the tail rather than on the leg. The SAP value obtained by HDO can be calculated from the Doppler measurement from SAP (HDO)=0.8515 × SAP (Doppler)+19.221 mmHg. Compared to Doppler, HDO overestimated low pressure and underestimated high pressure values.

Differences in heart rate variability during haemodialysis and haemofiltration

The aim of our study was to evaluate whether convective (haemofiltration, Hf) and diffusive (haemodialysis, Hd) dialysis techniques induce different patterns of long- and short-term autonomic adjustments in haemodynamically stable dialysis patients. Ten haemodynamically stable Hd patients were studied. Each patient underwent a block of six Hd sessions, then was switched to six Hf. During the last session of each dialytic treatment, continuous beat to beat measurements of systolic arterial pressure (SAP) and heart rate (HR) were performed. Spectral analysis of heart rate variability (HRV) was made before and during the treatment to evaluate the modification of autonomic nervous system activity. Baseline values of plasma sodium, body weight, HR and SAP were not different for the two considered methods of dialysis, while the baseline values of normalized LF were significantly higher in Hf as compared to Hd and the opposite was observed for HF powers (P < 0.001). Sodium balance and body weight loss per hour did not differ between Hd and Hf while body temperature was kept constant in all sessions. Throughout the dialytic procedures, with both techniques, SAP was constant, while HR diminished from the first hour till the end of the procedure (P < 0.05). An increase in LF (and decrease in HF) was noticed only in the case of Hd, considering normalized units (P < 0.05). These selective changes were maintained also during the recovery after the procedure. The spectral analysis of RR interval variability during Hd and Hf suggests a potential autonomic advantage with Hf, to be added to the well-recognized intrinsic greater haemodynamic stability.

Unique endothelial gene expression sensitivities to shear stress magnitude and spatial gradient

Indirect blood pressure measurements using high definition oscillometric (HDO) and Doppler devices were compared in 50 anaesthetised client-owned cats presented for various surgical procedures. Sites of cuff placement for Doppler were identified as forelimb and hindlimb and for HDO as forelimb and tail. Oscillometric and Doppler readings were obtained in 90.05% and 100% of attempts, respectively. Both devices enabled precise measurement of systolic arterial pressure (SAP), although the Doppler device gave higher precision. In the low pressure group (SAP < 100 mmHg; n = 30), 66.7% biases were within 10 mmHg of discrepancy, but in groups of normal (100 mmHg ≤ SAP ≤ 150 mmHg; n = 120) and high measurements (SAP > 150 mmHg; n = 62), 86.7% and 75.0% of discrepancy, respectively, were lower than 10 mmHg. Frequency of discrepancy at the range of 15 mmHg showed similar differences between pressure groups. There were significantly higher discrepancies when the cuff was positioned on the tail rather than on the leg. The SAP value obtained by HDO can be calculated from the Doppler measurement from SAP (HDO) = 0.8515 × SAP (Doppler) + 19.221 mmHg. Compared to Doppler, HDO overestimated low pressure and underestimated high pressure values.

Radial to femoral arterial blood pressure differences during liver transplantation

This observational study compared femoral and radial arterial blood pressure in 72 patients undergoing liver transplant surgery. Simultaneous femoral and radial arterial blood pressures, cardiac index, core temperature and vasoconstrictor therapy were recorded at seven time points during the operation. No significant differences between radial and femoral pressures were found at the start of surgery. Femoral and radial systolic arterial blood pressures were statistically significantly different during liver reperfusion (mean (SD) arterial pressure = 92 (22) mmHg vs. 76 (22) mmHg, p < 0.01). Mean arterial blood pressures showed no statistically significant differences throughout the study. Vasoconstrictor drug administration was associated with a larger systolic pressure difference between femoral and radial arteries (28 (24) mmHg in patients being given vasoconstrictor drugs vs. 9 (19) mmHg in patients not needing vasoconstrictors during reperfusion, p < 0.001). In conclusion, differences in systolic arterial blood pressure occur between femoral and radial arterial monitoring sites during liver reperfusion, and in particular in patients being given vasoconstrictor therapy. Thus, if femoral arterial monitoring is not available, clinicians should rely on mean rather than systolic arterial pressure measurements from a radial artery catheter during liver transplantation.

Correlation between baroreflex gain and 24-h indices of heart rate variability.

To examine the relationship between heart rate variability (HRV) and baroreflex sensitivity (BRS). An observational study, with no intervention, in 55 volunteers with a wide range of arterial pressure (60-90/115-185 mmHg). Volunteers were studied first in the laboratory, with continuous measurement of systolic arterial pressure and electrocardiogram to obtain a frequency domain measure of baroreflex sensitivity (index alpha). Immediately afterwards, while the individual was ambulant, a Holter recording was obtained in order to compute time domain [standard deviation of consecutive normal R-R intervals (SDNN) and the percentage of successive R-R differences > 50 ms (PNN50)], and frequency domain measures of HRV. Linear correlation was used to test the statistical link between index alpha and HRV indices. Significant correlations were observed between index alpha and SDNN (r = 0.30; P < 0.02) and PNN50 (r = 0.48; P < 0.001), and between index alpha and total power (r = 0.53; P < 0.001), and absolute powers of the 0.0001-0.04 Hz components of R-R interval variability in 24 h (r = 0.47; P < 0.001). The major findings of this study are the clear demonstration of a significant correlation between a laboratory measure of baroreflex sensitivity and 24 h measures of HRV, obtained immediately afterwards. Notably, this correlation was found with both time domain and absolute, but not normalized, spectral measures of R-R interval variability. In addition, different levels of individual activity, as assessed by separate examination of daytime and night-time periods, did not seem to influence this relationship.

A simplified plethysmographic system for the measurement of systemic arterial pressure and peripheral blood flow

A mercury strain-gauge plethysmographic system which employs an inexpensive, battery-powered, transistorized DC amplifier and a portable electrocardiographic recorder for the measurement of systolic arterial pressure and blood flow in the limbs is described. The accuracy of the plethysmographic method for determining systemic arterial pressure was demonstrated by comparing it with methods which simultaneously determined direct arterial pressures. The applicability to a variety of clinical problems of both the DC and AC amplifying systems was discussed. The technique has been found to be particularly useful in the preoperative and postoperative study of patients with coarctation of the aorta, in the study of newborn infants and older infants, and in patients of all ages who are in shock or in whom vasoconstriction is marked. It is also anticipated that the plethysmographic system utilizing the transistorized DC amplifier will simplify the measurement of blood flow in the limbs of patients with peripheral vascular disease.