Median Perfusion Index Research Articles

In Patients With Hypertension, the Cortical Perfusion Index Measured by Contrast Enhanced Ultrasound Reveals a Sexual Dimorphism.

Arterial hypertension is characterized by microvasculature changes and reduced tissue perfusion. It is unknown whether a sexual dimorphism of renal microcirculation is present in patients with arterial hypertension. We aimed to compare the cortical microcirculation in women and men with hypertension and to evaluate their response to sympathetic stimulation with a cold pressor test (CPT). The cortical perfusion index (PI) measured by contrast-enhanced ultrasonography was used as a proxy of renal microcirculation. We measured the PI at rest and during a 2-minute CPT in patients with arterial hypertension. We used a linear mixed-model analysis to study the effect of sex, the CPT, and their interaction on the PI. Thirty-two participants were included (34% women). Age and body mass index were similar in both groups. Median PI was higher in women (2344 [interquartile range, 1553-2685 arbitrary units]) than men (1285 [interquartile range, 591-1741 arbitrary units], P=0.009). The CPT increased the PI in both groups; however, the magnitude of the response to CPT was similar in both sexes. Women with arterial hypertension have a higher cortical microperfusion than men, while their microvascular reactivity to a CPT appears to be similar. This sexual dimorphism may have an impact on renal function decline, which needs further investigation.

The perfusion index as a noninvasive method for monitoring revascularized and replanted digits.

Monitoring replanted digits remains a challenging task in microsurgical units. Previous studies have indicated the perfusion index (PI), a parameter directly proportional to the blood flow, might be a useful tool. The PI is evaluated as a monitoring tool in patients with replanted digits. This prospective, non-interventional study includes 31 patients with revascularized or replanted digits. After successful revascularization or replantation, the PI and peripheral oxygen saturation of the affected finger and its contralateral equivalent were measured simultaneously. The values were detected by the device Radical-97® Pulse CO-Oximeter® (Masimo Corporation, 52 Discovery, Irvine, CA 92618, USA). The median PI of affected fingers was 3.5±0.56 for revascularized and 2.2±0.8 for replanted fingers. The difference between the PI values of replanted digits and the healthy contralateral side was highly significant (p < 0.0001). The area under the curve in the receiver operating characteristics was 0.92 for a PI difference > 80.49% and predicted a loss of replant with a specificity of 100% and a sensitivity of 75%. The assessment of the PI in patients with reperfusion of a vascular compromised digit is a useful tool to continuously monitor peripheral perfusion. The dynamic behavior of the PI is essential to detect perfusion disturbance.

Comparison of two different methods as reliable predictors of successful caudal block in children

ABSTRACT Background To reduce the dosages of the intraoperative anaesthetic and analgesic agents, the caudal block is most frequently used in children. The work aims to investigate the efficacy of perfusion index (PI) and heart rate (HR) variations following the caudal block in determining the onset and appropriateness of the caudal block in children. Patients and methods After induction of general anaesthesia, 0.5–1 ml/kg of 0.25% bupivacaine according to the needed block level using a 22-gauge needle. Bupivacaine dose was given as an initial injection of 0.2 ml/kg for 3–4 s; the remaining dose was given at the same flow after 1 min. The lowest HRs were observed during and up to 1 min after the initial injection, as well as during and up to 1 min after the complete drug delivery. Prior to and every 2 min following the caudal block, the PI of all children was measured. Results There was a significant difference between the caudal success group and the caudal failure group regarding median PI (p < 0.001). At the initial and total caudal bupivacaine doses, there was a significant fall between the median HR caudal success group and the median HR caudal failure group (p < 0.001). Conclusion A decrease in HR of −2 and −3 beats/minute during or shortly after an initial and entire caudal drug injection, respectively, and median PI are reliable methods in the prediction of caudal success.

Is perfusion index a surrogate indicator of left ventricular contractility in neonates? A prospective study.

Noninvasive blood pressure monitoring may not accurately reflect cardiac contractility in neonates due to low vascular tone. The perfusion index (PI) is a noninvasive method of assessing the strength of peripheral pulses. It is shown to have a significant correlation with the left ventricular output. This prospective study estimates the correlation between PI and cardiac contractility in neonates. All hemodynamically stable neonates who were on substantial enteral feeds and not on any respiratory or inotropic support underwent measurement of PI and echocardiography examination. Various indices of left ventricular contractility were estimated, and the correlation coefficient between them and PI was determined. Fifty-six neonates were studied. The median (interquartile range [IQR]) PI was 1.5 (1.25-1.75). The median (IQR) PI in preterm neonates was 1.5 (1.2-1.8) and that in term neonates was 1.8 (1.25-2.7) (P = 0.064). PI had a correlation of 0.205 with fractional shortening (P = 0.129) and 0.13 with left ventricular ejection fraction (P = 0.821). The Spearman's correlation coefficient between PI and velocity of circumference fiber shortening was 0.009 (P = 0.945). The Spearman's correlation coefficient between PI and cardiac output was -0.115 (P = 0.400). The PI does not correlate with left ventricular contractility parameters in neonates.

Perfusion Index as an Indicator for Mortality in Children with Plasmodium falciparum Severe Malaria

Background:Severe malaria (SM) remains a major global health problem causing ~275,000 pediatric deaths annually, worldwide. Continuous, non-invasive monitoring of peripheral perfusion can help detect abnormalities in systemic circulation, a common problem in critically ill patients, and can improve outcomes in children hospitalized with SM. Perfusion index (PI), an indicator of peripheral perfusion measured using a point-of-care pulse oximeter, is the ratio of pulsatile blood flow to static blood in peripheral tissue. Objective: To investigate the role of PI as an indicator of adverse outcomes including mortality in children hospitalized with SM. Methods: We measured PI in a prospective cohort study of 600 children &lt;5 years of age with 5 different clinical manifestations of SM, and 120 healthy community children (CC) at two hospitals in Uganda. PI was measured at 6-hr intervals during hospitalization using a Masimo Rad 57 pulse oximeter. Results: Children with SM had significantly lower admission PI values (1.2 [IQR: 0.58, 2.2] compared to CC (2.8 [1.7, 4.3], p&lt;0.001). Children with SM manifesting as respiratory distress syndrome or severe malarial anemia had lower median PI compared to other manifestations including cerebral malaria, the deadliest form of SM in children. In children with SM, a log decrease in admission PI was associated with 2.7 higher odds of in-hospital mortality (p=0.01). A log reduction in PI was also associated with in-hospital clinical complications associated with SM, including circulatory shock, deep acidotic breathing and acidosis, hypoglycemia, and severe anemia (all P&lt;0.03). In survivors of SM, there were no significant associations between PI and cognitive outcomes at 12-month follow-up. Conclusion: The role of PI as an indicator of mortality in children with SM and the use of point-of-care tools for continuous monitoring of PI warrants further investigation in the management of SM to prevent or reduce the incidence of adverse outcomes.

A study to evaluate the change in perfusion index as an indicator of successful ultrasound-guided supraclavicular block.

Background and Aims:Perfusion index (PI) is a new simple, objective and non-invasive method for evaluation of the success of central neuraxial and peripheral nerve blocks. So, we conducted a study with an aim to evaluate PI as an indicator for success of ultrasound-guided supraclavicular block (SCB).Methods:65 patients of either sex, age 18–60 years, American Society of Anesthesiologists physical status I and II posted for upper limb surgery under ultrasound (US)-guided SCB were included. PI was recorded at baseline every 2 minutes till 10 minutes and then every 5 minutes till 30 minutes after block. PI ratio was calculated as the ratio between PI at 10 minutes and baseline PI. Sensory and motor blocks were assessed at 5-minutes intervals up to 30 minutes. Descriptive analysis was applied by mean and standard deviation for quantitative, frequency and proportion for categorical variables.Results:Mean PI increased continuously from baseline and reached the maximum at 10 minutes and then slightly decreased up to 30 minutes, but values at subsequent time intervals were quite high as compared to baseline. In case of successful blocks, median PI started increasing 2 minutes after the block and then increased in a linear fashion till 10 minutes, whereas in case of failed blocks, it only increased minimally.Conclusion:PI is an objective and faster indicator for evaluating success of US-guided SCB. A cut-off value of 3.25 for PI and 3.03 for PI ratio showed a fairly good ability with high sensitivity and specificity for predicting the success of SCB.

Decreased peripheral perfusion measured by perfusion index is a novel indicator for cardiovascular death in patients with type 2 diabetes and established cardiovascular disease

Cardiovascular disease (CVD) is still the major cause of mortality in patients with type 2 diabetes. Despite of recent therapies, mortality and resources spent on healthcare due to CVD is still important problem. Thus, appropriate markers are needed to predict poor outcomes. Therefore, we investigated the role of peripheral perfusion as an indicator for cardiovascular death in patients with type 2 diabetes and established CVD. This retrospective cohort study included 1080 patients with type 2 diabetes and history of CVD recruited from the outpatient clinic at Matsushita Memorial Hospital in Osaka, Japan. Peripheral perfusion is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. The median age and PI values were 74 years (range: 67–79 years) and 2.6% (range: 1.1–4.3%), respectively. During follow-up duration, 60 patients died due to CVD. The adjusted Cox regression analysis demonstrated that the risk of developing cardiovascular death was higher in the first quartile (Hazard ratio, 6.23; 95% CI, 2.28 to 22.12) or second quartile (Hazard ratio, 3.04; 95% CI, 1.46 to 6.85) of PI than that in the highest quartile (fourth quartile) of PI. PI (per 1% decrease) was associated with the development of cardiovascular death (Hazard ratio, 1.39; 95% CI, 1.16 to 1.68). PI could be a novel indicator of cardiovascular death in patients with type 2 diabetes and established CVD.

440-P: Decreased Peripheral Perfusion Measured by Perfusion Index Is a Novel Indicator for Cardiovascular Death in Patients with Type 2 Diabetes and Established Cardiovascular Disease

We investigated the role of peripheral perfusion as an indicator for cardiovascular death in patients with type 2 diabetes and established cardiovascular disease (CVD). This retrospective cohort study included 1080 patients with type 2 diabetes and history of CVD recruited from the outpatient clinic at Matsushita Memorial Hospital in Osaka, Japan. Peripheral perfusion is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. PI was measured using a Masimo SET Radical-7 (Masimo Corporation, Irvine, CA) instrument. The median age and PI values were 74 years (range: 67-79 years) and 2.6% (range: 1.1-4.3%), respectively. The average duration of follow up was 871 ± 265 days. During follow-up duration, 60 patients died due to CVD. The adjusted Cox regression analysis demonstrated that the risk of developing cardiovascular death was higher in the first quartile (HR, 5.84; 95% CI, 2.23 to 20.16) or second quartile (HR, 3.00; 95% CI, 1.05 to 10.81) of PI than that in the highest quartile (fourth quartile) of PI. PI (per 1% decrease) was associated with the development of cardiovascular death (HR, 1.38; 95% CI, 1.15 to 1.64). PI could be a novel indicator of cardiovascular death in patients with type 2 diabetes and established CVD. Disclosure H. Okada: None. Y. Okada: None. M. Fukui: None.

Randomized Trial of Radial Hemostasis Using Focused vs Balloon Compression Devices.

Radial artery hemostasis devices differ in compression mechanisms, which may influence time to hemostasis and hand perfusion. Subjects (n = 52) undergoing transradial diagnostic coronary catheterization or percutaneous coronary intervention (PCI) were randomized 1:1 to either focused compression (VasoStat; Forge Medical) or balloon compression device (TR Band; Terumo Medical) for radial artery hemostasis. Time to complete hemostasis enabling device removal was measured in each subject. Hand perfusion was quantitated using the perfusion index (PI) with oximetry (1) before; (2) during device use; (3) during device use with ulnar artery compression; and (4) following device removal. Focused compression resulted in a significantly shorter time to complete hemostasis vs balloon compression (208 min [IQR, 115-320 min] vs 242 min [IQR, 120-439 min], respectively; P=.04). This difference was greatest among the subset undergoing PCI, where the VasoStat resulted in a 43-minute reduction until complete hemostasis (P=.04). Baseline PI was similar between the focused and balloon compression groups (4.9 vs 3.9, respectively; P=.09). Focused compression resulted in a similar reduction in median PI from baseline to during device use compared with balloon compression (-27% vs -18%, respectively; P=.26). Both devices decreased PI over 50% from baseline during simultaneous ulnar artery compression (P<.01), and increased PI over 50% from baseline following device removal (P=.02). No radial artery occlusion occurred, and rates of device manipulation and access-site bleeds were low in both groups. Complete hemostasis was achieved earlier with the VasoStat focused compression device compared with the TR Band balloon compression device. Both devices transiently reduced hand perfusion, particularly during ulnar compression, which increased from baseline following device removal. Larger trials comparing these radial hemostasis devices and outcomes are warranted.

Peripheral perfusion, measured by perfusion index, is a novel indicator for renal events in patients with type 2 diabetes mellitus

Diabetic kidney disease (DKD) is one of the leading causes of end stage renal disease. Despite recent therapies, mortality due to DKD and resources spent on healthcare are important problems. Thus, appropriate markers are needed to predict renal outcomes. Therefore, we investigated the role of peripheral perfusion as an indicator for renal events in patients with type 2 diabetes mellitus. This retrospective cohort study included 566 patients who were admitted to Matsushita Memorial Hospital in Osaka, Japan for type 2 diabetes mellitus. Peripheral perfusion was assessed using perfusion index (PI), which represents the level of circulation through peripheral tissues and was measured on each toe using a Masimo SET Radical-7 (Masimo Corporation, Irvine, CA, USA) instrument. The duration of follow up was 3.0 years. The median age of patients was 70 years (IQR range: 61–77 years) and median PI value was 2.9% (IQR range: 1.8–4.8%). Multiple logistic regression analyses showed that PI (per 1% increase) was associated with an odds ratio of composite of end-stage renal disease (ESRD) and/or doubling of serum creatinine level; n = 40 (odds ratio 0.823 [95% CI: 0.680–0.970]), and composite of ESRD, doubling of serum creatinine level, and renal death and/or cardiovascular death; n = 44 (odds ratio 0.803 [95% CI: 0.665–0.944]). The factors which were statistically significant in univariate analysis and those known to be related factors for renal event were considered simultaneously as independent variables for multiple logistic regression analysis. PI can be a novel indicator for renal events in patients with type 2 diabetes mellitus.

Decreased microcirculatory function measured by perfusion index is predictive of cardiovascular death.

The importance of microcirculation for adverse outcomes in the early phase of critical illnesses has been reported. Microcirculatory function is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. We investigated the correlation between PI and cardiovascular death to explore whether it can serve as a predictor of cardiovascular death. This retrospective study included 2171 patients admitted to Matsushita Memorial Hospital in Osaka, Japan, for medical treatment. We measured PI for all patients. To examine the effects of PI on cardiovascular death, a Cox proportional hazard model was used. The median age and PI values were 72years (range 63-79years) and 2.7% (range 1.4-4.6%), respectively. During the 3927.7 person-years follow-up period, a total of 54 patients died due to cardiovascular disease. PI was positively correlated with BMI (P < 0.0001) and total cholesterol levels (P = 0.004). PI was negatively correlated with age (P < 0.0001), heart rate (P < 0.0001), and creatinine levels (P < 0.0001). Adjusted Cox regression analyses demonstrated that PI was associated with an increased hazard of cardiovascular death (hazard ratio 0.84; 95% CI; range 0.72-0.99). In addition, compared with patients with a high PI (> 3.7%), those with a low PI (≤ 2.0%) had a significantly increased risk of cardiovascular death. This low PI group had a hazard ratio of 3.49 (95% CI 1.73-7.82). The PI is a valuable predictor for cardiovascular death in a clinical setting.

Decreased microcirculatory function measured by perfusion index is a novel indicator of diabetic kidney disease in patients with type2 diabetes.

Aims/IntroductionDiabetic kidney disease has been considered as an important risk factor of cardiovascular disease. Chronic hypoxia is considered to be the main cause of renal injury. Diminished microcirculatory blood flow could be associated with hypoxia in the kidney. Whether diminished microcirculation is associated with diabetic kidney disease has not yet been reported. Here, we investigated the correlation between microcirculatory function and diabetic kidney disease in patients with type 2 diabetes.Materials and MethodsOur cross‐sectional study included 574 patients who were admitted to Matsushita Memorial Hospital in Moriguchi, Japan, for type 2 diabetes. Microcirculatory function was assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. We measured the PI for all patients.ResultsThe median age and PI values were 70 years (range 60–77 years) and 2.8% (range 1.6–4.8%). Multiple regression analyses showed that the PI independently correlated with the logarithm of urinary albumin excretion (P = 0.009) and estimated glomerular filtration rate (P = 0.005), respectively. Multiple logistic regression analyses showed that patients with systolic blood pressure (SBP) greater than the median and PI less than or equal to the median (high‐low group) had a significantly increased odds of albuminuria compared with those with SBP less than or equal to the median and PI greater than the median (low‐high group), and patients with SBP greater than the median and PI less than or equal to the median (high‐low group) had a significantly increased odds of estimated glomerular filtration rate <60 mL/min per 1.73 m2 compared with those with SBP less than or equal to the median and PI greater than the median (low‐high group) or SBP greater than the median and PI greater than the median (high‐high group).ConclusionsPI could be a novel indicator of diabetic kidney disease in patients with type 2 diabetes.

Correlation between Perfusion Index and CRIB Score in Sick Neonates Admitted to a Tertiary Center.

The study was to determine the correlation of Perfusion Index (PI) and Clinical Risk Index for Babies (CRIB) score, in assessing the severity of illness in sick neonates. This was a cross-sectional study conducted at a tertiary care Neonatal Intensive Care Unit (NICU). All eligible neonates, both term and preterm, admitted to the high-dependency unit of the NICU were included, after parental consent. Relevant details of history and examination were collected with a structured proforma. Severity of illness was assessed using CRIB score within 12 h of admission. PI was recorded within 24 h of admission, and babies were examined for the presence or absence of shock and their outcome was documented. The correlation coefficient between PI and CRIB score was derived. A total of 200 eligible newborns were enrolled. The mean gestational age of the neonates was 34 weeks. The median [interquartile range (IQR)] CRIB score was 1.00 (0.00, 3.00), and PI was 1.400 (0.93, 2.30). The Spearman's rank correlation coefficient between PI and CRIB score was -0.41 with p value <0.05. The median PI of neonates with CRIB score ≤5, 6-10 and >10 was 1.50, 0.74, 0.67, respectively (p value <0.0001). The median (IQR) PI of babies with shock and without shock was 0.63 (0.43, 0.84) and 1.58 (1.19, 2.41), respectively, with p value <0.001. PI has a negative correlation with CRIB score and can be used to assess the severity of illness in sick neonates.

Perfusion index in healthy newborns during critical congenital heart disease screening at 24 hours: retrospective observational study from the USA

ObjectiveTo describe the distribution of perfusion index (PI) in asymptomatic newborns at 24 hours of life when screening for critical congenital heart disease (CCHD) using an automated data selection method.DesignThis...

Target value of oxygen saturation during the first 10min after birth.

During neonatal resuscitation, careful oxygenation is needed. Pulse oximetry is recommended to evaluate the need for oxygenation, but it is not clear whether peripheral perfusion is adequate for the evaluation of arterial oxygen saturation (SpO2 ). Additionally, there has been no study on the changes in SpO2 immediately after birth in Japan, despite the indispensable need for definitive oxygenation criteria. A prospective observational study was performed in neonates at gestational age 35-41weeks. An SpO2 measurement probe was attached to the neonates immediately after birth at the right palm or wrist, and the perfusion index (PI), pulse rate, and SpO2 were measured until 10min after birth. Sixty neonates were examined. Stable PI was obtained soon after birth, preceding SpO2 measurement. The median PI (%) was constant at approximately 1.3, and the median SpO2 at 2-10min was 70%, 81%, 82%, 87%, 89%, 92%, 92%, 94%, and 95%, respectively. The current target value for SpO2 in the Neonatal Cardiopulmonary Resuscitation (NCPR) guideline in Japan is approximately the 25th percentile. PI is stable and sufficient in the early postnatal period, meaning that peripheral perfusion is adequate for the measurement of SpO2 . The current target SpO2 used in the NCPR guidelines is at approximately the 25th percentile and is thought to be sufficient for meeting oxygenation criteria.

Effects of Two Different Exogenous Surfactant Preparations on Serial Peripheral Perfusion Index and Tissue Carbon Monoxide Measurements in Preterm Infants with Severe Respiratory Distress Syndrome

Administration of an exogenous surfactant may affect both ventilatory and hemodynamic parameters in preterm infants with respiratory distress syndrome (RDS). Peripheral perfusion may be expected to be influenced, and serial perfusion index (PI) values may show this effect. Noninvasive transcutaneous carbon monoxide (TCO) monitoring may show RDS severity, oxidative and inflammatory stress, and response to surfactant treatment. This randomized controlled nonblinded study was performed in 30 preterm infants with RDS, treated with poractant alfa (n = 15) or beractant (n = 15); 18 preterm infants without RDS served as a control group. Oxygenation and hemodynamic parameters were recorded and compared through the first 6 hours of treatment. PI and TCO values were measured prior to (Tp), immediately after (T0), and at 5 minutes (T5), 30 minutes (T30), 60 minutes (T60), and 360 minutes (T360) after the bolus surfactant administration. The mean arterial pressure, oxygenation index, pH, and lactate levels were recorded simultaneously. Both study groups had lower Tp PI and higher Tp TCO levels than controls. Both surfactant preparations improved the PI, TCO, mean arterial pressure, oxygenation index, pH, and lactate levels at the end point of T360. However, the median Tp PI value of 1.3 first decreased to 0.86 at T0 (P < 0.001), and then it increased to 0.99 at T5 (p < 0.001) and to 1.25 at T30 (p = 0.037). The median Tp TCO value of 3 decreased to 2, 1.5, 0, and 0 at T0, T5, T30, and T60, respectively (p < 0.001). PI more quickly recovered to Tp values (30 minutes vs. 60 minutes) and reached the control group values (30 minutes vs. 360 minutes) with beractant compared to that with poractant alfa. TCO recovered to Tp values in both groups at the same time (5 minutes vs. 5 minutes), but reached the control group values more quickly (5 minutes vs. 30 minutes) with poractant alfa than with beractant. Patients with RDS had poor perfusion, and PI improved with both surfactant preparations only following a short decline in the 1(st) minute. The expected improvement of PI occurred earlier in the beractant subgroup. TCO declined in both groups, showing lung improvement and decreased oxidative/inflammatory stress, and it was normalized earlier with poractant alfa.

Perfusion index in the very preterm infant

Perfusion Index (PI) is a quantifiable measurement of peripheral perfusion and may be a useful adjunct to the assessment of circulatory status in the newborn. (i) To assess reproducibility of PI and (ii) To determine whether there is a difference between simultaneously obtained limb measurements of PI in newborns <32 weeks GA in the transitional period. Perfusion Index was measured in newborns <32 weeks during the first 48 h of life. To examine reproducibility, the pulse oximetry probe was replaced on the same limb consecutively by the same operator. Upper and lower limbs were then simultaneously evaluated over a 5-min period. Heart rate, blood pressure, birth weight, ventilation requirement, inotrope use, lactate, PCO2 and CRIB-II score were also recorded. Thirty infants were assessed. Intraclass correlation coefficient for reproducibility in the same limb was high (r value = 0.982 p < 0.001). Measurements obtained in the right upper limb were consistently higher than either lower limb. The median (IQR) PI for the entire cohort was 0.70 (0.29-1.35). No correlation existed between gestational age, birth weight, CRIB scores, systolic and diastolic blood pressure, mean blood pressure and median PI values. Perfusion Index measurement is reproducible, and values are highest in the right upper limb. Wide differences between right upper and lower limb readings are most likely related to transitional circulatory changes.

Contrast-enhanced ultrasound to evaluate changes in renal cortical perfusion around cardiac surgery: a pilot study

IntroductionContrast-enhanced ultrasound (CEUS) is a new technique that might enable portable and non-invasive organ perfusion quantification at the bedside. However, it has not yet been tested in critically ill patients. We sought to establish CEUS's feasibility, safety, reproducibility and potential diagnostic value in the assessment of renal cortical perfusion in the peri-operative period in cardiac surgery patients.MethodsWe recruited twelve patients deemed at risk of acute kidney injury (AKI) planned for elective cardiac surgery. We performed renal CEUS with destruction-replenishment sequences before the operation, on ICU arrival and the day following the admission. Enhancement was obtained with Sonovue® (Bracco, Milano, Italy) at an infusion rate of 1 ml/min. We collected hemodynamic parameters before, during and after contrast agent infusion. At each study time, we obtained five video sequences, which were analysed using dedicated software by two independent radiologists blinded to patient and time. The main output was a perfusion index (PI), corresponding to the ratio of relative blood volume (RBV) over mean transit time (mTT).ResultsAll 36 renal CEUS studies, including 24 in the immediate post-operative period could be performed and were well tolerated. Correlation between readers for PI was excellent (R2 = 0.96, P < 0.0001). Compared with baseline, there was no overall difference in median PI's on ICU admission. However, the day after surgery, median PI's had decreased by 50% (P < 0.01) (22% decrease in RBV (P = 0.09); 48% increase in mTT (P = 0.04), both suggestive of decreased perfusion). These differences persisted after correction for haemoglobin; vasopressors use and mean arterial pressure. Four patients developed AKI in the post-operative period.ConclusionsCEUS appears feasible and well-tolerated in patients undergoing cardiac surgery even immediately after ICU admission. CEUS derived-parameters suggest a decrease in renal perfusion occurring within 24 hours of surgery.

Calf muscle perfusion at peak exercise in peripheral arterial disease: Measurement by first‐pass contrast‐enhanced magnetic resonance imaging

To develop a contrast-enhanced magnetic resonance (MR) technique to measure skeletal muscle perfusion in peripheral arterial disease (PAD). A total of 11 patients (age = 61 +/- 11 years) with mild to moderate symptomatic PAD (ankle-brachial index [ABI] = 0.75 +/- 0.08) and 22 normals were studied using an MR-compatible ergometer. PAD and normal(max) (Nl(max); N = 11) exercised to exhaustion. Nl(low) (N = 11) exercised to the same workload achieved by PAD. At peak exercise, 0.1 mm/kg of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was infused at 3-4 cm(3)/second followed by a saline flush at the same rate. A dual-contrast gradient echo (GRE) sequence enabled simultaneous acquisition of muscle perfusion and arterial input function (AIF). The perfusion index (PI) was defined as the slope of the time-intensity curve (TIC) in muscle divided by the arterial TIC slope. Median workload was 120 Joules in PAD, 210 Joules in Nl(low), and 698 Joules in Nl(max) (P < 0.001 vs. Nl(low) and PAD). Median PI was 0.29 in PAD (25th and 75th percentiles [%] = 0.20, 0.40), 0.48 in Nl(low) (25th, 75th % = 0.36, 0.62; P < 0.02 vs. PAD), and 0.69 in Nl(max) (25th, 75th % = 0.5, 0.77; P < 0.001 vs. PAD). Area under the ROC-curve for PI differentiating patients from Nl(max) was 0.95 (95% confidence interval [CI] = 0.77-0.99). Peak-exercise measurement of lower limb perfusion with dual-contrast, first-pass MR distinguishes PAD from normals. This method may be useful in the study of novel therapies for PAD.

Disruption of circulatory and respiratory activity in shore crabs ( Carcinus maenas (L.)) exposed to heavy metal pollution

1. Cardiac and respiratory activity of the shore crab, Carcinus maenas (L.), were disrupted following exposure to heavy metal ions. 2. Exposure to 3 mg l −1 copper ions induced continuous, uninterrupted heart beat in quiescent, undisturbed crabs. Copper ions (10 mg l −1) suppressed cardiac activity and oxygen consumption within 2 hr. Alternating periods of bradycardia and tachycardia were observed together with marked changes in impedance cardiograph trace height. 3. Similar, but more pronounced changes were seen following exposure to 1 mg l −1 mercury ions. 4. Median perfusion index was 100 ml blood ml O 2 −1 (range 58–114 ml blood ml O 2 −1) prior to pollution, but increased to peak values within the range 90–220 ml O 2 −1 following exposure to copper or mercury. 5. The effects of exposure to copper were transient and largely reversible. 6. Exposure to mercury resulted in 100% mortality 24–48 hr after initial contamination. Death was apparently associated with loss of the osmoregulatory ability of these crabs.