Noninvasive Continuous Cardiac Output Monitoring Research Articles

Occurrence of Low Cardiac Index During Normotensive Periods in Cardiac Surgery: A Prospective Cohort Study Using Continuous Noninvasive Cardiac Output Monitoring.

Continuous cardiac output monitoring is not standard practice during cardiac surgery, even though patients are at substantial risk for systemic hypoperfusion. Thus, the frequency of low cardiac output during cardiac surgery is unknown. We conducted a prospective cohort study at a tertiary medical center from July 2021 to November 2023. Eligible patients were ≥18 undergoing isolated coronary bypass (CAB) surgery with the use of cardiopulmonary bypass (CPB). Cardiac output indexed to body surface area (CI) was continuously recorded at 5-second intervals throughout surgery using a US Food and Drug Administration (FDA)-approved noninvasive monitor from the arterial blood pressure waveform. Mean arterial blood pressure (MAP) and central venous pressure (CVP) were also analyzed. Low CI was defined as <2 L/min/m2 and low MAP as <65 mm Hg. We calculated time with low CI for each patient for the entire surgery, pre-CPB and post-CPB periods, and the proportion of time with low CI and normal MAP. We used Pearson correlation to evaluate the relationship between CI and MAP and paired Wilcoxon rank sum tests to assess the difference in correlations of CI with MAP before and after CPB. In total, 101 patients were analyzed (age [standard deviation, SD] 64.8 [9.8] years, 25% female). Total intraoperative time (mean [SD]) with low CI was 86.4 (62) minutes, with 61.2 (42) minutes of low CI pre-CPB and 25.2 (31) minutes post-CPB. Total intraoperative time with low CI and normal MAP was 66.5 (56) minutes, representing mean (SD) 69% (23%) of the total time with low CI; 45.8 (38) minutes occurred pre-CPB and 20.6 (27) minutes occurred post-CPB. Overall, the correlation (mean [SD]) between CI and MAP was 0.33 (0.31), and the correlation was significantly higher pre-CPB (0.53 [0.32]) than post-CPB (0.29 [0.28], 95% confidence interval [CI] for difference [0.18-0.34], P < .001); however, there was substantial heterogeneity among participants in correlations of CI with MAP before and after CPB. Secondary analyses that accounted for CVP did not alter the correlation between CI and MAP. Exploratory analyses suggested duration of low CI (C <2 L/min/m2) was associated with increased risk of postoperative acute kidney injury (odds ratios [ORs] = 1.09; 95% CI; 1.01-1.13; P = .018). In a prospective cohort of patients undergoing CAB surgery, low CI was common even when blood pressure was normal. CI and MAP were correlated modestly. Correlation was higher before than after CPB with substantial heterogeneity among individuals. Future studies are needed to examine the independent relation of low CI to postoperative kidney injury and other adverse outcomes related to hypoperfusion.

Hemodynamic Changes of Women with Preeclampsia Undergoing Spinal Anesthesia for Emergency Cesarean Section: A Prospective Observational Study

Abstract Background: Preeclampsia is a multisystem disorder in pregnancy and remains a significant cause of maternal morbidity and mortality. In this prospective observational study, we used a continuous noninvasive cardiac output monitor to investigate the changes in arterial blood pressure, cardiac output, systemic vascular resistance, stroke volume, and stroke volume variation during the immediate perioperative period. Materials and Methods: Women with preeclampsia undergoing emergency cesarean section under spinal anesthesia were recruited in this prospective observational study. Cardiac output and arterial blood pressures were measured by the Nexfin monitor. Cardiovascular parameters were recorded intraoperatively and up to 48 h postoperatively. The primary outcome was to examine the differences in cardiac output between the intraoperative and postoperative periods. Results: Thirty patients included in the data analysis had a mean age of 35.6 ± 5.2 years and gestation of 35.4 ± 2.1 weeks. Post-spinal anesthesia, 50% experienced hypotension. 26.7% had nausea, 10% vomited, and other events included shivering, reactive hypertension, and bradycardia. The use of spinal anesthesia was associated with a significant reduction in systolic (126.7 ± 16.9 vs. 142.0 ± 21.2 mm Hg, P &lt; 0.001), diastolic (71.2 ± 8.4 vs. 77.0 ± 11.3 mm Hg, P &lt; 0.001), mean arterial pressure (92.6 ± 12.2 vs. 103.7 ± 15.3 mm Hg, P &lt; 0.001), cardiac output, and stroke volume compared to postoperative readings. No significant difference was found in cardiac output, cardiac index, or systemic vascular resistance indices between the intraoperative and postoperative periods. Conclusion: Spinal anesthesia may have short-term hemodynamic changes in women with preeclampsia. Continuous noninvasive cardiac monitoring can be used to monitor specific cardiac hemodynamic parameters, which may resolve in the immediate postoperative period.

Comparison of parameter types for the calibration of noninvasive continuous cardiac output monitoring of patients undergoing lumbar spinal surgery in the prone position.

Cardiac output (CO) decreases on reversing the patient's position to the prone position. Estimated continuous cardiac output (esCCO) systems can noninvasively and continuously monitor CO calibrated by patient information or transesophageal echocardiogram (TEE). To compare the accuracy, precision, and trending ability of two calibration methods of CO estimation in patients in prone position. The CO estimates calibrated by TEE (esT) and patient information (esP) of 26 participants were included. CO was collected at four time points. The accuracy and precision of agreement were evaluated using the Bland-Altman method. A four-quadrant plot was used for trending ability analysis. The bias between esP and TEE and between esT and TEE was 0.2594 L/min (95% limits of agreement (LoA): -1.8374 L/min to 2.3562 L/min) and 0.0337 L/min (95% LoA: -0.7381 L/min to 0.8055 L/min), respectively. A strong correlation was found between ΔesP and ΔTEE (p< 0.001, CCC = 0.700) and between ΔesT and ΔTEE (p< 0.001, CCC = 0.794). The concordance rates between ΔesP and ΔTEE and between ΔesT and ΔTEE were 91.9% and 97.1%, respectively. Despite limited accuracy and precision, esP showed acceptable trending ability. The trending ability of esCCO calibrated by the reference TEE value was comparable with that of TEE.

The Value of Noninvasive Continuous Cardiac Output Monitoring in Assessment of Hemodynamic Status in Critically Ill Children

Access to reliable, rapid, and continuous hemodynamic monitoring parameters is essential for early diagnosis and prompt treatment of hemodynamic disorders in critically ill children. The aim of this observational study was to compare the accuracy of continuous non-invasive cardiac output monitoring (NICCOMO) device data with transthoracic echocardiography (TTE) and inferior vena cava (IVC) ultrasound findings in assessing cardiac output (C.I), circulatory fluid adequacy, and finally Determination of hemodynamic status in patients with Critical conditions hospitalized in the Pediatric Intensive Care Unit (PICU). In this observational study, forty-four critically ill children that were admitted to PICU were evaluated. We used NICCOMO, TTE, and IVC ultrasonography at the same time in critical patients. The association between NICCOMO parameters and echocardiogram cardiac index and IVC quality in ultrasound is compared. The agreement between CI measured by TTE and NICCOMO was assessed using the Bland-Altman analysis method. NICCOMO is not a reliable instrument for determining CI in children with an unstable hemodynamic status. However, the parameters of this device are reliable in assessing the patient's hemodynamic status. Findings showed that 90% of patients in the normal hemodynamic state in NICCOMO have SVR. I in the normal range (P&lt;0.001), and all cases in hypervolemic state had volume overload IVC in ultrasonography analysis. Noninvasive continuous cardiac output monitoring could be used to estimate unstable patients’ hemodynamic status in the initial stages for making timely treatment-related decisions, but its use for accurate cardiac index measurement is not reliable in all cases.

Non-invasive continuous cardiac output monitoring in infants with hypoxic ischaemic encephalopathy

ObjectiveTo describe early, continuous, non-invasive measures of cardiac output (CO) and evolution over time in infants with hypoxic-ischaemic encephalopathy (HIE).Study designProspective observational study of 44 infants with HIE (23 mild, 17 moderate, 4 severe) and 17 term controls. Infants with HIE had non-invasive CO monitoring (NICOM) continuously in the neonatal unit. Term controls had NICOM recorded at 6 and 24 h. A mixed-modelling approach was used to assess change in CO over time by group.ResultsInfants with moderate HIE have significantly lower CO than the mild group at all timepoints (10.7 mls/kg/min lower, 95% CI:1.0,20.4, p = 0.03) which increases over time, driven by a gradual increase in stroke volume (SV). CO increased further during rewarming predominantly due to an increase in HR.ConclusionTH has a significant impact on HR but SV appears largely unaffected. NICOM may provide a non-invasive, continuous, low-cost alternative to monitoring CO in infants with HIE however further research is warranted.

Perioperative Continuous Noninvasive Cardiac Output Monitoring in Cardiac Surgery Patients by a Novel Capnodynamic Method

To test the clinical performance of a novel continuous noninvasive cardiac output (CO) monitoring based on expired carbon dioxide kinetics in cardiac surgery patients. A prospective feasibility pragmatic clinical study. A single-center, large community hospital. Thirty-two patients undergoing cardiac surgery were studied during the intraoperative (before cardiopulmonary bypass) and postoperative (in the intensive care unit before extubation) periods. CO was measured simultaneously by the continuous capnodynamic method and by transpulmonary thermodilution during changes in the patient's hemodynamic and/or respiratory conditions. The current recommended comparative statistics for CO measurement methods were analyzed, including bias, precision, and percentage error obtained from Bland-Altman analysis, and concordance between methods obtained from the four-quadrant plot analysis to evaluate the trending ability. Bias ± limits of agreement and percentage error were -0.6 (-1.9 to +0.8; 95% CI of 3.73-5.25) L/min and 31% (n=147 measurements) for the intraoperative period, -0.8 (-2.4 to +0.9; 95% CI of 3.03-5.21) L/min and 41% (n=66) for the postoperative period, and -0.6 (-2.1 to +0.8; 95% CI of 3.74-5.00) L/min and 34% (n=213) for the pooled data. The trending analysis obtained a concordance of 82% (n=65) for the intraoperative and 71% (n=24) for the early postoperative periods. Aggregation of both data sets gave a concordance of 79% (n=89). The continuous capnodynamic method was reliable and in good agreement with the reference method, and had an accuracy and trending ability good enough tomake it a possible future alternative for hemodynamic monitoring in the studied population of elective adult cardiac surgery patients.

Non-invasive continuous cardiac output monitoring in thoracic cancer surgery

BACKGROUND Patients scheduled for thoracic cancer surgery are eligible for goal-directed fluid therapy, but cardiac output monitoring remains challenging in that specific setting. OBJECTIVE We aimed to compare cardiac output as measured with chest bioreactance with that measured by calibrated pulse contour analysis; the hypothesis being that both methods would be interchangeable. DESIGN A prospective monocentre observational study. SETTING A tertiary university hospital. PATIENTS Fifty adult patients undergoing thoracic cancer surgery over a one year period. MAIN OUTCOME MEASURES Simultaneous measurements of cardiac index (CI) with bioreactance (CI-NICOM) and arterial pulse contour analysis calibrated by transthoracic echocardiography (CI-PCA) were performed at eight pre-specified intra-operative time points and following fluid challenge and/or vasoactive agents. Relationships between absolute values and changes in CI were assessed by linear regression. Interchangeability was tested with Bland–Altman analysis and percentage error calculation. A four quadrant plot was used to evaluate trending ability. RESULTS There was a significant difference between CI-PCA and CI-NICOM: 2.4 ± 0.8 (range: 0.9 to 5.8) l min−1 m−2 vs. 2.9 ± 0.9 (range: 0.9 to 7.2) l min−1 m−2, respectively (P &lt; 0.001). A positive relationship was found between both techniques: y = 0.29x + 2.19; r 2 = 0.08 (P &lt; 0.001). Taking CI-PCA as the reference method, there was a systematic overestimation of CI-NICOM by 21% (0.5 l min−1 m−2) and limits of agreement were large: -2.49 to 1.47 l min−1 m−2. The percentage error was 77% and concordance rates were 75 and 70% with and without an exclusion zone of 0.5 l min−1 m−2. CONCLUSION Chest bioreactance is feasible and well tolerated in patients undergoing thoracic surgery for cancer. When compared with calibrated PCA over a wide range of CI values, the technique is moderately correlated, not interchangeable, and provides moderate trending ability. TRIAL REGISTRATION NCT04251637.

Electrical velocimetry (ICON cardiometry) assessment of hemodynamic changes associated with different inflation pressures during pediatric thoracoscopic surgery: a pilot study

Background Advances in endoscopic equipment and techniques have led to the use of minimally invasive thoracic surgery in an increasing number of pediatric surgical procedures. Logically, thoracoscopic surgery and anesthesia can induce significant physiologic changes; here comes the importance of an accurate, noninvasive cardiac output (CO) monitor for early diagnosis and management for any significant complications.Aims This study aimed to assess the effect of different intrathoracic pressures (ITP; insufflation pressures 4, 5, and 6 mmHg) during thoracoscopic surgeries in neonates and infants on hemodynamics using electrical velocimetry (ICON) as a noninvasive monitoring technique.Patients and methods This prospective pilot study was conducted in Abu El-Reesh Children’s Hospital, Kasr Al-Ainy Hospital, Faculty of Medicine, Cairo University, from November 2019 to January 2020. After obtaining ethical committee approval (D-6-2019) and registering at www.clinicaltrials.gov with the number NCT04131699, and after obtaining the consent of parents/legal guardians, 12 neonates and infants who presented for thoracoscopic surgery and met our selection criteria were included in the study. After standard premedication, monitoring, and anesthesia induction, for electrical velocimetry, an ‘ICON CARDIOTRONIC, OSYPKA MEDICAL’ continuous noninvasive CO monitor was attached to the patients according to the manufacturer’s instructions in neonates and infants. All patients’ data, including sex, height, and weight, were entered into the device, which estimated cardiovascular parameters at a 20-beat moving average recorded every 10 s. Cardiac index, CO, stroke volume, noninvasive arterial blood pressure, and heart rate readings had been taken in every patient. Records were taken before inflation of the chest as a baseline reference, 1 min after inflation of the chest as the ITP reaches 4 mmHg, then the ITP was increased to 5 mmHg, and the readings were taken after an extra 1 min. Finally, the ITP was increased to 6 mmHg, and the readings were taken after an additional 1 min.Results A total of 14 patients were screened for eligibility; of them, two patients were excluded for not meeting the inclusion criteria, and 12 patients were included. The median (interquartile range) age of patients was 4.5 (3–28) days. Sex distribution was equal (six males and six females). The cardiac index showed no significant increase with raising the pleural pressure (PP) by CO2 insufflation and postdeflation in comparison with baseline (preinsufflation). The CO showed no significant increase with raising the PP by CO2 insufflation in comparison with baseline (preinsufflation). Mean arterial blood pressure showed no significant change with gradual increase in PP and after deflation in comparison with preinflation readings; however, heart rate showed significant decrease after deflation in comparison with baseline (preinsufflation).Conclusion Hemodynamic stability was maintained during thoracoscopic surgery in neonates as measured by ICON. Further studies including systemic vascular resistance need to be done to give more explanation about hemodynamic affection during positive PP inflation. Moreover, different age groups, different patients’ positions, and patients with cardiac and pulmonary lesions need to be included to assess the various effects of pleural insufflation on these populations.

Effect of Endovascular Treatment on Systemic Vascular Resistance in Patients with Lower-Limb Peripheral Artery Disease.

Objective: Endovascular treatment (EVT) for lower-limb peripheral artery disease patients reduces blood pressure (BP) and improves prognosis. This study retrospectively examined hemodynamics during EVT to clarify the mechanism.Materials and Methods: Systemic vascular resistance (SVR) was measured using a noninvasive continuous cardiac output monitoring system during EVT. Furthermore, ankle brachial index was measured before and after EVT.Results: The study included 88 lesions of 56 patients (hypertension in 98%). SVR significantly decreased from 2409.1±746.8 dynes·s·cm−5 to 2033.7±635.0 dynes·s·cm−5 (p<0.0001). The difference in SVR before and after EVT was significantly greater in the Fontaine IV group than in the Fontaine IIa group (554.7±406.6 dynes·s·cm−5 vs. 312.9±245.7 dynes·s·cm−5, p=0.0151). The change in SVR was correlated with a change in mean BP in the upper limb (p=0.0026). When the change in pressure gradient between the upper limb and the diseased lower limb was large, mean BP of the upper limb significantly decreased (p=0.0022).Conclusion: EVT can reduce SVR and BP by canceling the pressure gradient between central BP and diseased lower-limb BP.

Postoperative continuous non-invasive cardiac output monitoring on the ward: a feasibility study

Postoperative hypotension is common (occurring in one third of patients) and is associated with worse clinical outcomes. The LiDCO CNAP (continuous non-invasive arterial pressure) device measures haemodynamics but has not been widely adopted in ward environments. Improved early detection of hypotension by CNAP might guide interventions to improve clinical outcomes. We aimed to find the proportion of patients who tolerated LiDCO CNAP for 12 h postoperatively, to unmask episodes of hypotension detected by continuous monitoring and to characterise the haemodynamic profile at the time of hypotension. In this feasibility study, patients undergoing major elective surgery were continuously postoperatively monitored using CNAP. Haemodynamic data gathered from CNAP, including nSVRI (nominal systemic vascular resistance index), nSVI (nominal stroke volume index), SVV (stroke volume variation) and blood pressure, were analysed using Microsoft Excel and GraphPad Prism 8. 104 patients (age (mean ± sd): 68 ± 14, male (56%)) had CNAP sited postoperatively. 39% tolerated the CNAP device for at least 12 h. Within the 104 patients a mean of 81.2 min of hypotension detected by CNAP was not detected by usual care. The proportion of low/normal/high nSVI was 71%, 27% and 2%, nSVRI was 43%, 17% and 40%, respectively. CNAP monitoring was not tolerated for 12 h in the majority of patients. There were many episodes of hypotension unmasked through continuous monitoring. Based on the advanced haemodynamic data provided it is possible that the underlying cause of a third of postoperative hypotensive episodes is vasodilation rather than hypovolaemia.Trial registry number: NCT04010058 (ClinicalTrials.gov) Date of registration: 08/07/2019.

Non-invasive Continuous Cardiac Output Monitoring in Preterm Infants Study

Non-invasive Continuous Cardiac Output Monitoring in Preterm Infants Study

Progress in noninvasive assessment of fluid responsiveness

Fluid infusion is one of the most common therapeutic measures in clinical practice. With the development of medical technology, the assessment of fluid responsiveness before fluid infusion has become simpler and less invasive. The assessment of fluid responsiveness is based on three aspects: cardiopulmonary interaction, volume-loading test and endogenous volume-loading test. This article reviews the progress in the assessment of fluid responsiveness with the application of ultrasound and noninvasive continuous cardiac output monitoring, and the prospect of future improvement. Key words: Noninvasive; Ultrasound; Continuous cardiac output monitoring; Fluid responsiveness

Comparison of dexmedetomidine versus propofol on hemodynamics in surgical critically ill patients

BackgroundSedation with dexmedetomidine and propofol may cause hypotension or bradycardia. This study aimed to compare the effects of dexmedetomidine and propofol on hemodynamics and clinical outcomes in surgical intensive care unit (ICU) patients after major abdominal surgery. Materials and methodsEnrolled patients were randomly allocated to the dexmedetomidine or propofol group. Cardiac index was measured using a continuous noninvasive cardiac output monitor on the basis of chest bioreactance. Heart rate, blood pressure, opioid requirement, urine output, delirium incidence, ICU length of stay, and total hospital length of stay were compared between the two groups. The incidences of bradycardia, hypotension, and severe low cardiac index were compared. ResultsWe enrolled 60 patients. Heart rate and mean arterial pressure were significantly lower in the dexmedetomidine group than in the propofol group. Cardiac index did not differ significantly between the two groups (dexmedetomidine group 3.1 L/min/m2, [95% confidence interval {95% CI} 2.8-3.3] versus propofol group 3.2 L/min/m2 [95% CI 2.9-3.5], P = 0.578). The incidences of bradycardia, hypotension, and severe low cardiac index did not differ significantly between the two groups. ConclusionsCardiac index did not differ significantly between the dexmedetomidine and propofol groups in surgical ICU patients after major abdominal surgery.

Responsiveness of Noninvasive Continuous Cardiac Output Monitoring During the Valsalva Maneuver.

To describe the baseline hemodynamic variables and response time of hemodynamic changes associated with the Valsalva maneuver using noninvasive continuous cardiac output monitoring (Nexfin). Hemodynamic monitoring provides an integral component of advanced clinical care and the ability to monitor response to treatment interventions. The emergence of noninvasive hemodynamic monitoring provides clinicians with an opportunity to monitor and assess patients rapidly with ease of implementation. However, the responsiveness of this method in tracking dynamic changes that occur has not been fully elucidated. A prospective observational study was conducted involving 44 healthy volunteers (age = 38 ±12 years). Participants performed a Valsalva maneuvers to illicit dynamic changes in blood pressure, cardiac output, cardiac index, systemic vascular resistance index (SVRI), and stroke volume. Changes in these hemodynamic parameters were monitored while performing repeated standardized Valsalva maneuvers. Baseline hemodynamic values were obtained in all 44 participants, and showed an interaction with age, accompanying a significant decline in cardiac index (r = -.66, p < .05) and stroke volume (r = -.68,p < .05), and an increase in SVRI (r = .67, p < .05) with increasing age. The Valsalva maneuver, performed in 20 participants, resulted in a change of 10% from baseline blood pressure and cardiac index, which was detected within 4.53 s (SD = 4.36) and 3.31 s (SD = 2.21), respectively. Noninvasive continuous cardiac monitoring demonstrated the ability to rapidly detect logical and predictable hemodynamic changes. These observations suggest that such Nexfin technology may have useful clinical applications.

Noninvasive continuous blood pressure monitoring by the ClearSight system during robot-assisted laparoscopic radical prostatectomy.

Robot-assisted laparoscopic radical prostatectomy (RALRP) is commonly performed in the surgical treatment of prostate cancer. However, the steep Trendelenburg position (25) and pneumoperitoneum required for this procedure can sometimes cause hemodynamic changes. Although blood pressure is traditionally monitored invasively during RALRP, the ClearSight system (BMEYE, Amsterdam, The Netherlands) enables a totally noninvasive and simple continuous blood pressure and cardiac output monitoring based on finger arterial pressure pulse contour analysis. We therefore investigated whether noninvasive continuous arterial blood pressure measurements using the ClearSight system were comparable to those obtained invasively in patients undergoing RALRP. Ten patients scheduled for RALRP with American Society of Anesthesiologists physical status I-II were included in this study. At each of the seven defined time points, noninvasive and invasive blood pressure measurements were documented and compared in each patient using Bland-Altman analysis. Although the blood pressure measured with the ClearSight system correlated with that measured invasively, a large difference between the values obtained by the two devices was noted. The ClearSight system was unable to detect blood pressure accurately during RALRP, suggesting that blood pressure monitoring using this device alone is not feasible in this small patient population. J. Med. Invest. 65:69-73, February, 2018.

Robotic hysterectomy in Trendelenburg position in a severely anaemic JKa alloimmunised patient with impending high-output cardiac failure: An anaesthetic challenge.

Kidd blood group alloimmunisation, though extremely rare, may produce considerable morbidity, and even mortality. Severe anaemia and impending high-output cardiac failure requiring blood transfusion should be weighed against the risk of severe transfusion reactions even with fully cross-matched blood. Kidd antibodies are a common cause of delayed haemolytic transfusion reaction (DHTR) since they have a tendency remain undetectable in plasma. A low -grade DHTR (second hit) was grossly amplified by a second DHTR (third hit) superimposed on it in our patient leading to severe haemolysis with serum bilirubin reaching 68 mg%. Indirect antiglobulin test (indirect Coombs reaction) should ideally be performed in all patients (scheduled for major surgery requiring blood transfusion) who have experienced a previous pregnancy or blood transfusion. Non-invasive continuous haemoglobin monitoring and non-invasive cardiac output monitoring can prove invaluable tools in management.

Maternal hemodynamics: a method to classify hypertensive disorders of pregnancy

The classification of hypertensive disorders of pregnancy is based on the time at the onset of hypertension, proteinuria, and other associated complications. Maternal hemodynamic interrogation in hypertensive disorders of pregnancy considers not only the peripheral blood pressure but also the entire cardiovascular system, and it might help to classify the different clinical phenotypes of this syndrome. This study aimed to examine cardiovascular parameters in a cohort of patients affected by hypertensive disorders of pregnancy according to the clinical phenotypes that prioritize fetoplacental characteristics and not the time at onset of hypertensive disorders of pregnancy. At the fetal-maternal medicine unit of Ziekenhuis Oost-Limburg (Genk, Belgium), maternal cardiovascular parameters were obtained through impedance cardiography using a noninvasive continuous cardiac output monitor with the patients placed in a standing position. The patients were classified as pregnant women with hypertensive disorders of pregnancy who delivered appropriate- and small-for-gestational-age fetuses. Normotensive pregnant women with an appropriate-for-gestational-age fetus at delivery were enrolled as the control group. The possible impact of obesity (body mass index ≥30 kg/m2) on maternal hemodynamics was reassessed in the same groups. Maternal age, parity, body mass index, and blood pressure were not significantly different between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and hypertensive disorders of pregnancy/small-for-gestational-age groups. The mean uterine artery pulsatility index was significantly higher in the hypertensive disorders of pregnancy/small-for-gestational-age group. The cardiac output and cardiac index were significantly lower in the hypertensive disorders of pregnancy/small-for-gestational-age group (cardiac output 6.5 L/min, cardiac index 3.6) than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group (cardiac output 7.6 L/min, cardiac index 3.9) but not between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and control groups (cardiac output 7.6 L/min, cardiac index 4.0). Total vascular resistance was significantly higherin the hypertensive disorders of pregnancy/small-for-gestational-age group than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group and the control group. All women with hypertensive disorders of pregnancy showed signs of central arterial dysfunction. The cardiovascular parameters were not influenced by gestational age at the onset of hypertensive disorders of pregnancy, and no difference was observed between the women with appropriate-for-gestational-age fetuses affected by preeclampsia or by gestational hypertension with appropriate-for-gestational-age fetuses. Women in the obese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and obese/hypertensive disorders of pregnancy/small-for-gestational-age groups showed a significant increase in cardiac output, as well as significant changes in other parameters, compared with the nonobese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and nonobese/hypertensive disorders of pregnancy/small-for-gestational-age groups. Significantly low cardiac output and high total vascular resistance characterized the women with hypertensive disorders of pregnancy associated with small for gestational age due to placental insufficiency, independent of the gestational age at the onset of hypertension. The cardiovascular parameters were not significantly different in the women with appropriate-for-gestational-age or small-for-gestational-age fetuses affected by preeclampsia or gestational hypertension. These findings support the view that maternal hemodynamics may be a candidate diagnostic tool to identify hypertensive disorders in pregnancies associated with small-for-gestational-age fetuses. This additional tool matches other reported evidence provided by uterine Doppler velocimetry, low vascular growth factors in the first trimester, and placental pathology. Obesity is associated with a significantly higher cardiac output and outweighs other determinants of hemodynamics in pregnancy; therefore, in future studies on hypertensive disorders, obesity should be studied as an additional disease and not simply as a demographic characteristic.

Diagnostic Accuracy of Pulse Pressure Variation Compared to Thoracic Fluid Content in Mechanically Ventilated Patients after Cardiac Surgery

Background: In clinical area, assessment of body fluid and determination of the intravascular volume after major surgeries such as heart surgery is a significant challenge. The initial purpose of intravascular volume assessment in patients with hemodynamic instability is to determine whether they would benefit from fluid administration or not. Objectives: This study aims to compare pulse pressure variation (PPV) compared to thoracic fluid content in checking out and optimizing fluid volume in mechanically ventilated patients admitted to intensive care unit after cardiac surgery. Methods: In the present study a prospective descriptive-analytic design was used. Thirty mechanically ventilated patients admitted to intensive care units of Rajaie heart center, Tehran, Iran, were recruited in the current study after cardiac surgery based on inclusion criteria. Data collection tools included demographic and clinical data sheets. Hemodynamic parameters such as CVP and pulse pressure were recorded by bedside monitoring. Thoracic fluid content (TFC) was measured by non-invasive continuous cardiac output monitoring (NICCOMO) system. Data were analyzed in SPSS version 15, using statistical tests. Results: The mean values of CVP, before and five minutes after fluid administration were significantly different (10.10 ± 6.01 mmHg and 12.37 ± 6.34 mmHg, respectively, P = 0.015). The mean changes in arterial pulse pressure, before and five minutes after fluid administration were significantly different (16.94 ± 8.32 mmHg and 12.77 ± 4.02 mmHg, respectively, P = 0.005). PPV greater than 13% had sensitivity, specificity and positive predictive value of 40%, 71% and 75% respectively while CVP greater than 5 mmHg had sensitivity, specificity and positive predictive of 13%, 85% and 66% respectively compared with cardiac index as the gold standard for fluid responsiveness. These findings suggest a higher diagnostic power of PPV compared to CVP to assess fluid volume. Conclusions: It seems that in the mechanically ventilated patients after heart surgery, PPV dynamic index is preferred to CVP static index to evaluate and maintain fluid volume.

Comparing the Rates of Dopamine Hemodynamic Effect Onset after Infusion through Peripheral Veins in Three Regions.

Background Dopamine is an inotropic agent that is often selected for continuous infusion. For hemodynamic stability, the rate of infusion is controlled in the range of 5-15 μg/kg/min. This study aimed to compare the time intervals from the administration of dopamine to the onset of its hemodynamic effects when dopamine was administered through three different peripheral veins (the cephalic vein [CV], the great saphenous vein [GSV], and the external jugular vein [EJV]).Methods Patients in group 1, group 2, and group 3 received dopamine infusions in the CV, GSV, and EJV, respectively. A noninvasive continuous cardiac output monitor (NICCOMO™, Medis, Ilmenau, Germany) was used to assess cardiac output (CO) and systemic vascular resistance (SVR). Six minutes after intubation, baseline heart rate (HR), systolic blood pressure (BP), diastolic BP, mean arterial pressure (MAP), CO, and SVR values were recorded and dopamine infusion was initiated at a dose of 10 μg/kg/min. Hemodynamic changes at 0, 4, 8, 12, and 15 minutes postinfusion were recorded.Results No statistically significant differences were observed among the three groups with respect to the rate of hemodynamic change. In all groups, systolic BP, diastolic BP, MAP, and SVR tended to increase after decreasing for the first 4 minutes; in contrast, HR and CO decreased until 8 minutes, after which they tended to reach a plateau.Conclusions For patients under general anesthesia receiving dopamine at 10 μg/kg/min, there were no clinical differences in the effect of dopamine administered through three different peripheral veins.

Age-related incidence of desaturation events and the cardiac responses on stroke index, cardiac index, and heart rate measured by continuous bioimpedance noninvasive cardiac output monitoring in infants and children undergoing general anesthesia

Study objectiveTo assess the effects of desaturation on stroke index (SI), cardiac index (CI), and heart rate (HR) using the ICON continuous noninvasive cardiac output monitor in children undergoing general anesthesia. DesignRetrospective analysis of a prospectively collected data set. SettingPediatric operating rooms in a tertiary academic medical center. PatientsChildren younger than 20 years who experienced desaturation while undergoing general anesthesia. InterventionAll records were retrospectively searched for desaturation events defined as a recorded Spo2 ≤ 90%. We compared the data from the prior 4 minutes (baseline) with mild, moderate, and severe levels of desaturation. MeasurementsThe relationship between Spo2 and percent change in SI, CI, and HR from baseline was assessed using a generalized linear model with repeated measures and the least-squares method. Main resultsData from 446 patients were reviewed; 38 events were eligible for analysis after exclusions. There were significant decreases in SI at all saturation ranges below 95%: −6.5% (P < .001) for 85%-95%, −8.9% (P = .002) for 71%-84%, and −11% (P < .001) for ≤70%. Based on the result from the regression, Spo2 was associated with change in SI with borderline significance (P = .053) but not that of HR and CI. There was a strong relationship to desaturation events with young age (P < .001), particularly infants younger than 6 months. ConclusionEvents associated with desaturation in children under general anesthesia were significantly associated with decreased SI with a greater effect with lower saturation nadirs. It is unclear if other concurrent events could have also contributed to adverse hemodynamic responses during desaturation. In most children, a compensatory increase in HR generally offsets concurrent decreases in CI. It would appear that bradycardia is a late manifestation of hypoxemia.