Cardiac Output Monitoring Research Articles

P.99 Empowering midwives with arterial-line management

Introduction: Arterial pulse waveform analysis provides beat- to-beat monitoring of maternal cardiac output and is increasingly utilised in the management of obstetric patients. Common indications include preeclampsia, haemorrhage, obesity or cardiac disease. Such patients would ordinarily be managed in a high dependence or critical care area and 18% of women cared for in our obstetric high dependency unit required invasive arterial monitoring. We observed varying degrees of comfort amongst midwifery staff on managing arterial lines and sought to formally assess this.

Temporal haemodynamic changes after bisoprolol treatment in patients with uncontrolled hypertension.

BackgroundAnti-hypertensive drugs are widely used to control blood pressure, yet their effects on haemodynamics, especially in Chinese populations, and the potential for non-invasive methods to monitor these changes, are poorly understood. This study aimed to determine the early and late effects of bisoprolol treatment on blood pressure, cardiac output (CO), stroke volume (SV), heart rate (HR), systematic vascular resistance (SVR), and inotropy measured in Chinese patients with hypertension.MethodsTwelve Chinese subjects (median age: 55 years, interquartile range: 52–58 years; 33% male) with uncontrolled hypertension were recruited at the Prince of Wales Hospital in Hong Kong and haemodynamic measurements were assessed using a non-invasive Ultrasonic Cardiac Output Monitor (USCOM). Seven hourly measurements were taken before and after bisoprolol 2.5 mg on day 1 (T0 to T6), and in nine patients this was repeated six weeks later (TF0 to TF6). Any BP change of 5 mmHg was considered clinically significant and P<0.05 was considered statistically significant.ResultsOn day 1 (N=12), there was a significant drop in median CO [4.9 (4.7–5.6) vs. 3.8 (3.3–4.7) L/m2, P<0.0001] associated with a compensatory increase in SVR [1,698.1 (1,584.6–1,894.3) vs. 2,222.6 (1,777.4–2,712.5) d·s·cm−5, P<0.0001] at T2. The median dBP {92 [87–95] vs. 86 [79–89] mmHg, P=0.0002} and MAP {110 [104–114] vs. 104 [101–109] mmHg, P=0.038} reduced significantly 6 hours after bisoprolol treatment. Except for HR, all other measured haemodynamics returned to baseline at T6. On week 6 (N=9), SVR was generally reduced, but major parallel swings in CO and SVR were still evident. All patients showed a trend to lower blood pressure, SVR, and inotropy (P<0.05), but HR, SV, and CO returned to baseline values after 6 weeks treatment (P>0.05).ConclusionsThe acute haemodynamic changes between 6 hours of the first dose and the dose after 6 weeks of bisoprolol treatment are similar. Long-term therapy can effectively reduce blood pressure by reducing SVR.

Cardiac Output and Cerebral Oxygenation in Term Neonates during Neonatal Transition.

The immediate transition from foetus to neonate includes substantial changes, especially concerning the cardiovascular system. Furthermore, the brain is one of the most vulnerable organs to hypoxia during this period. According to current guidelines for postnatal stabilization, the recommended parameters for monitoring are heart rate (HR) and arterial oxygen saturation (SpO2). Recently, there is a growing interest in advanced monitoring of the cardio-circulatory system and the brain to get further objective information about the neonate’s condition during the immediate postnatal transition after birth. The aim of the present study was to combine cardiac output (CO) and brain oxygenation monitoring in term neonates after caesarean section in order to analyse the potential influence of CO on cerebral oxygenation during neonatal transition. This was a monocentric, prospective, observational study. For non-invasive cardiac output measurements, the electrical velocimetry (EV) method (Aesculon Monitor, Osypka Medical, CA, USA) was used. The pulse oximeter probe for SpO2 and HR measurements was placed on the right hand or wrist. The cerebral tissue oxygen index (cTOI) was measured using a NIRO-200NX monitor with the near-infrared spectroscopy (NIRS) transducer on the right frontoparietal head. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, mean CO was calculated from six 10 s periods (with beat-to-beat analysis). During the study period, 99 term neonates were enrolled. Data from neonates with uncomplicated transitions were analysed. CO showed a tendency to decrease until minute 10. During the complete observational period, there was no significant correlation between CO and cTOI. The present study was the first to investigate a possible correlation between CO and cerebral oxygenation in term infants during the immediate neonatal transition. In term infants with uncomplicated neonatal transition after caesarean section, CO did not correlate with cerebral oxygenation.

Bioreactance-derived haemodynamic parameters in the transitional phase in preterm neonates: a longitudinal study.

Bioreactance (BR) is a novel, non-invasive technology that is able to provide minute-to-minute monitoring of cardiac output and additional haemodynamic variables. This study aimed to determine the values for BR-derived haemodynamic variables in stable preterm neonates during the transitional period. A prospective observational study was performed in a group of stable preterm (< 37weeks) infants in the neonatal service of Tygerberg Children's Hospital, Cape Town, South Africa. All infants underwent continuous bioreactance (BR) monitoring until 72h of life. Sixty three preterm infants with a mean gestational age of 31weeks and mean birth weight of 1563g were enrolled. Summary data and time series graphs were drawn for BR-derived heart rate, non-invasive blood pressure, stroke volume, cardiac output and total peripheral resistance index. All haemodynamic parameters were significantly associated with postnatal age, after correction for clinical variables (gestational age, birth weight, respiratory support mode). To our knowledge, this is the first paper to present longitudinal BR-derived haemodynamic variable data in a cohort of stable preterm infants, not requiring invasive ventilation or inotropic support, during the first 72h of life. Bioreactance-derived haemodynamic monitoring is non-invasive and offers the ability to simultaneously monitor numerous haemodynamic parameters of global systemic blood flow. Moreover, it may provide insight into transitional physiology and its pathophysiology.

Maternal haemodynamics during labour epidural analgesia with and without adrenaline.

Labour is one of the most painful experiences in a woman's life. Epidural analgesia using low-concentration local anaesthetics and lipophilic opioids is the gold standard for pain relief during labour. Pregnancy in general, particularly labour, is associated with changes in maternal haemodynamic variables, such as cardiac output and heart rate, which increase and peak during uterine contractions. Adrenaline is added to labour epidural solutions to enhance efficacy by stimulating the α2-adrenoreceptor. The minimal effective concentration of adrenaline was found to be 2μgmL-1 for postoperative analgesia. The addition of adrenaline may also produce vasoconstriction, limiting the absorption of fentanyl into the systemic circulation, thereby reducing foetal exposure. However, adrenaline may influence the haemodynamic fluctuations, possibly adding to the strain on the circulatory system. The aim of this study was to compare the haemodynamic changes after application of labour epidural analgesia with or without adrenaline 2μgmL-1. This was a secondary analysis of a single-centre, randomised double-blind trial. Forty-one nulliparous women in labour requesting epidural analgesia were randomised to receive epidural solution of bupivacaine 1mgmL-1, fentanyl 2μgmL-1 with or without adrenaline 2μgmL-1. The participants were monitored using a Nexfin CC continuous non-invasive blood pressure and cardiac output monitor. The primary outcomes were changes in peak systolic blood pressure and cardiac output during uterine contraction within 30min after epidural activation. The effect of adrenaline was tested statistically using a linear mixed-effects model of the outcome variables' dependency on time, adrenaline, and their interaction. After excluding three patients due to poor data quality and two due to a malfunctioning epidural catheter, 36 patients (18 in each group) were analysed. The addition of adrenaline to the solution had no significant effect on the temporal changes in peak systolic blood pressure (p=0.26), peak cardiac output (0.84), or heart rate (p=0.91). Furthermore, no significant temporal changes in maternal haemodynamics (peak systolic blood pressure, p=0.54, peak cardiac output, p=0.59, or heart rate p=0.55) were associated with epidural analgesia during 30min after epidural activation in both groups despite good analgesia. The addition of 2μgmL-1 adrenaline to the epidural solution is not likely to change maternal haemodynamics during labour.

Ultrasonic cardiac output monitor provides effective non-invasive bedside measurements of neonatal cardiac output.

This study determined the accuracy and validity for the haemodynamic parameters of haemodynamically stable neonates after postnatal circulatory adaptation using the ultrasonic cardiac output monitor (USCOM) in comparison with echocardiography. We conducted a prospective, observational study of neonates born at 23-41weeks of gestation. They all underwent both echocardiography and USCOM assessments for comparison purposes. The 127 neonates were examined at the median of postmenstrual age of 35weeks and there was a very high correlation between the cardiac output measurements provided by both methods. The mean difference in cardiac output was -12 ± 25ml/kg/min, with percentage error of 8.3 ± 6.9%. A larger bias was observed in cases with higher left ventricular output. Bland-Altman analysis confirmed no significant bias, with acceptable limits of agreement between these two methods. There was a very good correlation between the USCOM and echocardiographic methods when we used them to measure cardiac output in neonates.

Non-invasive assessment of fluid responsiveness to guide fluid therapy in patients with sepsis in the emergency department: a prospective cohort study

BackgroundLittle is known about optimal fluid therapy for patients with sepsis without shock who present to the ED. In this study, we aimed to quantify the effect of a fluid...

Central hemodynamic monitoring in patients with cardiogenic shock

Cardiogenic shock is the pathology most commonly encountered by intensive care physicians. Its frequency averages 410% in STEMI (ST-elevation myocardial infarction) patients and 24% in NONSTEMI (non-ST-elevation myocardial infarction) patients. Effective shock therapy is impossible without understanding the hemodynamic mechanisms of its occurrence. Many authors emphasize that cardiac output is the most important indicator of cardiac function, which necessitates its monitoring. Meanwhile, the cardiac output monitoring is associated with a number of difficulties, including those related to the technology of recording this function. In this article, the authors emphasize the importance of measuring central hemodynamic parameters in patients with predominantly cardiogenic shock. We have tried to structure the knowledge about different techniques of central hemodynamics monitoring, considered advantages and disadvantages of each of them. We believe that the data obtained by hemodynamic monitoring should be closely studied and used, because sometimes multidirectional mechanisms may be involved in the genesis of shock; therefore, therapy should be based on the data obtained in a particular patient.

Effect of norepinephrine challenge on cardiovascular determinants assessed using a mathematical model in septic shock: a physiological study.

The present study investigated the cardiovascular determinants of cardiac output (CO), mean systemic filling pressure analogue (Pmsa) derived by Geoffrey Parkin, efficiency of heart (Eh) and related parameters to a norepinephrine (NE) challenge [an increase of 10 mmHg mean arterial pressure (MAP) by NE] in septic shock patients using of a mathematical model. Twenty-seven septic shock patients with pulse index continuous cardiac output (PiCCO) monitoring were enrolled. These patients required NE to maintain an individualized MAP for organ perfusion after early fluid resuscitation based on their clinical condition. NE was decreased to obtain a decrease of 10 mmHg from base MAP (MAP-10mmHg), and the NE doses were adjusted to return MAP to baseline (MAPbase) and produce an increase of 10 mmHg from MAPbase (MAP+10mmHg). Two NE challenge episodes were analyzed for each patient: from MAP-10mmHg to MAPbase and from MAPbase to MAP+10mmHg. The Pmsa, pressure gradient for venous return (PGvr), and Eh (PGvr relative to Pmsa) were estimated using a mathematical model for the three MAP levels (MAP-10mmHg, MAPbase and MAP+10mmHg). A total of 54 episodes of NE challenges were obtained in 27 patients. Significant and consistent increases were observed in the central venous pressure (CVP), Pmsa, and PGvr in response during the NE titration. ΔCO negatively and significantly correlated with ΔCVP (r=-0.722, P<0.0001), ΔPmsa (r=-0.549, P<0.0001), ΔResistance of venous return (Rvr) (r=-0.597, P<0.0001), and ΔResistance of systemic vascular beds (Rsys) (r=-0.597, P<0.0001). Episodes of decreasing CO/Eh were associated with a higher ΔCVP than the CO/Eh-increasing episodes. The area under the curve (AUC) of ΔCVP to predict decreased CO by the incremental NE was 0.86, and the AUC of ΔCVP to predict decreased Eh was 0.94. A cutoff of ΔCVP >1.5 mmHg for detecting decreased CO resulted in a sensitivity of 75% and a specificity of 94.1%. A cutoff of ΔCVP >1.5 mmHg for detecting decreased Eh resulted in a sensitivity of 64.3% and a specificity of 100%. There were a highly divergent response in Eh and CO to afterload challenge episodes of an NE-induced 10mmHg increase in MAP. An increase in CVP may be an early alarm to identify the reduction in CO/Eh during an NE-induced increase of MAP.

Agreement between continuous and intermittent pulmonary artery thermodilution for cardiac output measurement in perioperative and intensive care medicine: a systematic review and meta-analysis

BackgroundPulmonary artery thermodilution is the clinical reference method for cardiac output monitoring. Because both continuous and intermittent pulmonary artery thermodilution are used in clinical practice it is important to know whether cardiac output measurements by the two methods are clinically interchangeable.MethodsWe performed a systematic review and meta-analysis of clinical studies comparing cardiac output measurements assessed using continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients. 54 studies with 1522 patients were included in the analysis.ResultsThe heterogeneity across the studies was high. The overall random effects model-derived pooled estimate of the mean of the differences was 0.08 (95%-confidence interval 0.01 to 0.16) L/min with pooled 95%-limits of agreement of − 1.68 to 1.85 L/min and a pooled percentage error of 29.7 (95%-confidence interval 20.5 to 38.9)%.ConclusionThe heterogeneity across clinical studies comparing continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients is high. The overall trueness/accuracy of continuous pulmonary artery thermodilution in comparison with intermittent pulmonary artery thermodilution is good (indicated by a pooled mean of the differences < 0.1 L/min). Pooled 95%-limits of agreement of − 1.68 to 1.85 L/min and a pooled percentage error of 29.7% suggest that continuous pulmonary artery thermodilution barely passes interchangeability criteria with intermittent pulmonary artery thermodilution.PROSPERO registration number CRD42020159730.

Методика оценки количества жидкости в грудной клетке, основанная на антропометрических данных пациента и определении электрического импеданса грудной клетки

Актуальность. Определение в динамике объема жидкости в грудной клетке приобретает все более широкое распространение в клинических исследованиях и является перспективным методом мониторинга у пациентов отделений интенсивной терапии различного профиля. Наиболее доступными и экономичными методами мониторинга объема жидкости в грудной клетке в настоящее время являются методы, основанные на измерении электрического импеданса грудной клетки при сканировании ее высокочастотным током. Эти методики обеспечивают хорошую повторяемость результатов и практически не зависят от оператора. Цель работы: разработка собственной оригинальной методики определения содержания жидкости в грудной клетке. Материалы и методы. Электрический грудной импеданс измерялся при сканировании грудной клетки электрическим током частотой 32 КГц с наложением двух пар ленточных электродов по В. Кубичеку. Окружность основания шеи и грудной клетки в месте наложения электродов была тщательно измерена. Также опреде­лялось расстояние между измерительными электродами. Объем грудной клетки рассчитывался на основании модели усеченного конуса. Объем жидкости в грудной клетке рассчитывался по формуле V = γν/Z(R – r), где V — объем жидкости в грудной клетке; γ — усредненное значение электропроводности крови; ν — объем грудной клетки, рассчитанный на модели усеченного конуса; Z — величина электрического импеданса грудной клетки; R — радиус грудной клетки, а r — радиус основания шеи, внесение разницы между ними в формулу должно уменьшить ошибку, связанную с присутствием в грудной клетке соединительной ткани, обладающей электропроводностью, которая отличается от электропроводности крови. Исследования проведены как у практически здоровых добровольцев, так и у пациентов отделения политравмы с торакальной травмой и признаками дыхательной недостаточности. Результаты. Наши наблюдения показали, что величина объема жидкости в грудной клетке, вычисленная по предлагаемой нами методике, в норме приближается к 60 % — 59 ± 2 % объема грудной клетки, рассчитанного на основе модели усеченного конуса. В наиболее тяжелых случаях торакальной травмы относительное содержание жидкости в грудной клетке пострадавших достигало 75–80 %, а величина объема жидкости в грудной клетке, выраженная в условных единицах на 1/КΩ, находилась на уровне 45–50 условных 1/КΩ. Эти события были ассоциированы с наличием клинической картины острого респираторного дистресс-синдрома 2-й степени тяжести, и все пациенты находились на принудительной искусственной вентиляции легких (ИВЛ) с созданием постоянного положительного давления в дыхательных путях и респираторного плато на уровне 25–27 см Н2О. Положительная динамика процесса была ассоциирована с возрастанием величины индекса оксигенации, возможностью перевода пациентов на самостоятельное дыхание. При этом относительное содержание жидкости в грудной клетке пострадавших снижалось до 60–67 %, а у тех, кто нуждался в продолжении ИВЛ, — до 68–73 %. Величина объема жидкости в грудной клетке, выраженная в условных единицах на 1/КΩ, при быстром улучшении и возможности прекращения ИВЛ составляла 37–42 условных 1/КΩ, а при необходимости продол­жения ИВЛ — 43–46 условных 1/КΩ. Результаты определения объема жидкости в грудной клетке по методу авторов лучше соответствовали клинической картине торакальной травмы, тяжести проявлений синдрома острой дыхательной недостаточности, чем показатели методики NICOM. Выводы. Разработанная методика определения содержания жидкости в грудной клетке может быть применена в научных исследованиях и клинической практике в процессе проведения интенсивной терапии у пациентов с синдромом острой дыхательной недостаточности.

Velocity-pressure loops can estimate intrinsic and pharmacologically induced changes in cardiac afterload during non-cardiac surgery. An observational study.

Continuous measurement of aortic pressure and aortic flow velocity signals in the operating theatre allows us to draw velocity-pressure (Vel-Pre) loops. The global afterload angle (GALA), derived from the Vel-Pre loops, has been linked to cardiac afterload indicators. As age is the major determinant of constitutive arterial stiffness, we aimed to describe (1) the evolution of the GALA according to age in a large cohort of anesthetized patients and (2) GALA variations induced by haemodynamic interventions. We included patients for whom continuous monitoring of arterial pressure and cardiac output were indicated. Fluid challenges or vasopressors were administered to treat intra-operative hypotension. The primary endpoint was the comparison of the GALA values between young and old patients. The secondary endpoint was the difference in the GALA values before and after haemodynamic interventions. We included 133 anaesthetized patients: 66 old and 67 young patients. At baseline, the GALA was higher in the old patients than in young patients (38 ± 6 vs. 25 ± 4 degrees; p < 0.001). The GALA was positively associated with age (p < 0.001), but the mean arterial pressure (MAP) and cardiac output were not. The GALA did not change after volume expansion, regardless of the fluid response, but it did increase after vasopressor administration. Furthermore, while a vasopressor bolus led to a similar increase in MAP, phenylephrine induced a more substantial increase in the GALA than noradrenaline (+ 12 ± 5° vs. + 8 ± 5°; p = 0.01). In non-cardiac surgery, the GALA seems to be associated with both intrinsic rigidity (reflected by age) and pharmacologically induced vasoconstriction changes (by vasopressors). In addition, the GALA can discriminate the differential effects of phenylephrine and noradrenaline. These results should be confirmed in a prospective, ideally randomized, trial.

Extravascular Lung Water and Intrathoracic Blood Volume Index Are Associated With Liver Function in Brain Dead Donors for Organ Transplant.

Hemodynamic measurements during organ transplant procedures are essential. In this observational study, we measured clinical and hemodynamic parameters in 11 patients with advanced pulse indicator continuous cardiac output monitoring. Normally distributed clinical data were calculated as means ± standard deviation; hemodynamic, metabolic, and respiratory parameters related to liver and renal function were compared by linear regression analysis using Pearson correlation. Compared with the normal range, systemic vascular resistance was high (2278.02 ± 719.6 dyne·s/cm²/m²) and intrathoracic blood volume was low (787.37 ± 224.01 mL/m²) in our patient group. C-reactive protein and interleukin 6 levels were 96.26 ± 68.10 mg/mL and 246.24 ± 355.74 mmol/L, respectively. Liver and renal function parameters were in normal ranges. Extravascular lung water was correlated with total, conjugated, and unconjugated bilirubin and albumin (r = 0.342/P = .005; r = 0.338/ P = .005; r = 0.394/P = .001, and r = 0.358/P = .003) but not with aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Intrathoracic blood volume index was correlated with total bilirubin, unconjugated bilirubin, and albumin (r = 0.324/P = .007; r = 0.394/P = .001, and r = 0.296/P = .015) but not with conjugated bilirubin, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Lactate was not correlated with total bilirubin, unconjugated bilirubin, albumin, and serum creatinine, but base excess was correlated with total bilirubin, unconjugated bilirubin, alanine aminotransferase, and albumin. PO₂ and Pco₂ were not correlated with liver function, although PO₂ was correlated with albumin. No correlations were shown between intrathoracic blood volume index, extravascular lung water, and liver function, but metabolic parameters, including base excess and lactate, were correlated with liver function. Pulse indicator continuous cardiac output monitoring may be a useful method to assess organ function and tissue perfusion in organ transplant.

New Advances in Monitoring Cardiac Output in Circulatory Mechanical Assistance Devices. A Validation Study in a Porcine Model.

Cardiac output (CO) measurement by continuous pulmonary artery thermodilution (COCTD) has been studied in patients with pulsatile-flow LVADs (left ventricular assist devices), confirming the clinical utility. However, it has not been validated in patients with continuous-flow LVADs. Therefore, the aim of this study was to assess the validity of COCTD in continuous-flow LVADs. Continuous-flow LVADs were implanted in six miniature pigs for partial assistance of the left ventricle. Both methods of measuring CO—measurement by COCTD and intermittent pulmonary artery thermodilution, standard technique (COITD)—were used in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading), and hypovolemia (shock hemorrhage). At the basal moment, COCTD and COITD were closely correlated (r2 = 0.97), with a mean bias of −0.13 ± 0.16 L/min and percentage error of 11%. After 15 min of partial support LVAD, COCTD and COITD were closely correlated (r2 = 0.91), with a mean bias of 0.31 ± 0.35 L/min and percentage error of 20%. After inducing hypervolemia, COCTD and COITD were closely correlated (r2 = 0.99), with a mean bias of 0.04 ± 0.07 L/min and percentage error of 5%. After inducing hypovolemia, COCTD and COITD were closely correlated (r2 = 0.74), with a mean bias of 0.08 ± 0.22 L/min and percentage error of 19%. This study shows that continuous pulmonary thermodilution could be an alternative method of monitoring CO in a porcine model with a continuous-flow LVAD.

The ability of pulse oximetry-derived peripheral perfusion index to detect fluid responsiveness in patients with septic shock.

Fluid challenge test is a widely used method for the detection of fluid responsiveness in acute circulatory failure. However, detection of the patient's response to the fluid challenge requires monitoring of cardiac output which is not feasible in many settings. We investigated whether the changes in the pulse oximetry-derived peripheral perfusion index (PPI), as a non-invasive surrogate of cardiac output, can detect fluid responsiveness using the fluid challenge testor not. We prospectively enrolled 58 patients with septic shock on norepinephrine infusion. Fluid challenge test, using 200mL crystalloid solution, was performed in all study subjects. All patients received an additional 300mL crystalloid infusion to confirm fluid responsiveness. Velocity time integral (VTI) (using transthoracic echocardiography), and PPI were measured at the baseline, after 200mL fluid challenge, and after completion of 500mL crystalloids. Fluid responsiveness was defined by 10% increase in the VTI after completion of the 500mL. The predictive ability of ∆PPI [Calculated as (PPI after 200mL - baseline PPI)/baseline PPI] to detect fluid responders was obtained using the receiver operating characteristic curve. Forty-two patients (74%) were fluid responders; in whom, the mean arterial pressure, the central venous pressure, the VTI, and the PPI increased after fluid administration compared to the baseline values. ∆PPI showed moderate ability to detect fluid responders [area under receiver operating characteristic curve (95% confidence interval) 0.82 (0.70-0.91), sensitivity 76%, specificity 80%, positive predictive value 92%, negative predictive value 54%, cutoff value ≥ 5%]. There was a significant correlation between ∆PPI and ∆VTI induced by the fluid challenge. ∆PPI showed moderate ability to detect fluid responsiveness in patients with septic shock on norepinephrine infusion. Increased PPI after 200mL crystalloid challenge can detect fluid responsiveness with a positive predictive value of 92%; however, failure of the PPI to increase does not exclude fluid responsiveness. NCT03805321. Date of registration: 15 January 2019. Clinical trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03805321?term=ahmed+hasanin&rank=9 .

Application of pulse contour cardiac output monitoring technology in fluid resuscitation of severe burn patients in shock period

Objective: To investigate the application of pulse contour cardiac output (PiCCO) monitoring technology in fluid resuscitation of severe burn patients in shock period. Methods: From January 2015 to December 2019, 33 patients with severe burns who were hospitalized in Guangzhou Red Cross Hospital, meeting the inclusion criteria, were recruited into a retrospective cohort study with their clinical information collected. The patients were divided into PiCCO monitoring group with 15 cases (13 males and 2 females, aged (43±13) years) and routine monitoring group with 18 cases (14 males and 4 females, aged (39±9) years) according to the monitoring method used. After admission, all the patients were rehydrated following the rehydration formula of the Third Military Medical University for shock period. In routine monitoring group, the fluid resuscitation of patients was performed by monitoring indicators such as urine volume and blood pressure, while PiCCO monitoring was performed among patients in PiCCO monitoring group, and their fluid resuscitation was guided by the patient's condition and the hemodynamic parameters (without pursuing normal levels of the parameters) of PiCCO monitoring on the basis of normal monitoring indicators in routine monitoring group. The colloids coefficients, the electrolyte coefficients (compared with the corresponding rehydration formula value of 0.75 mL·kg(-1)·% total body surface area (TBSA)(-1) of the Third Military Medical University for shock period during the first 24 h post injury), the total rehydration coefficients, and the urine volumes during the first and second 24 h post injury, the lactic acid level, the base excess level, and the oxygenation index at admission and 24, 48 h after admission, and the mechanical ventilation time, the wound healing time, and the death ratio of patients in the two groups were recorded. The cardiac index, the global end-diastolic volume index (GEDVI), the intrathoracic blood volume index (ITBVI), the extravascular lung water index (EVLWI), and the systemic vascular resistance index (SVRI) of patients in PiCCO monitoring group at post injury hour 24, 48, and 72 and the abnormal cases were recorded. Data were statistically analyzed with Fisher's exact probability test, independent-sample or one-sample t test, analysis of variance for repeated measurement, and Bonferroni correction. Results: During the first 24 h post injury, the colloids coefficients of patients in PiCCO monitoring group was (0.69±0.15) mL·kg(-1)·%TBSA(-1), which was significantly less than (0.85±0.16) mL·kg(-1)·%TBSA(-1) in routine monitoring group (t=-2.612, P<0.05). Compared with the rehydration formula value of the Third Military Medical University for shock period, only the colloids coefficient of patients in routine monitoring group during the first 24 h post injury was significantly increased (t=2.847, P<0.05). There were no statistically significant differences between the two groups in the colloids coefficients of patients during the second 24 h post injury, or the electrolyte coefficients, the total rehydration coefficients, the urine volumes of patients during the first and the second 24 h post injury (t=0.579, -0.011, 0.417, -1.321, -0.137, 0.031, 1.348, P>0.05). The lactic acid level, the base excess level, the oxygenation index of patients at admission and 48 h after admission, and the oxygenation index of patients at 24 h after admission between the two groups were similar (t=-1.837, 0.620, 0.292, -1.792, 1.912, -0.167, 1.695, P>0.05). The levels of lactic acid and base excess of patients in PiCCO monitoring group were (4.8±1.4) and (1.2±5.5)mmol/L, respectively, which were significantly better than (7.0±1.5) and (-2.8±3.0) mmol/L in routine monitoring group at 24 h after admission (t=-3.904, 2.562, P<0.05 or P<0.01). There were no statistically significant differences between the two groups in the mechanical ventilation time or the wound healing time of patients (t=-0.699, -0.697, P>0.05), or the death ratio of patients (P>0.05). In PiCCO monitoring group, the GEDVI, and the ITBVI of patients were lower than the normal low values at post injury hour 24 and 48, which were in the normal range at post injury hour 72; the cardiac index of patients increased gradually and recovered to normal at post injury hour 48; the SVRI of patients increased significantly at post injury hour 24 and then gradually decreased to normal; the EVLWI average of patients at all time points post injury were less than 10 mL/kg. At post injury hour 24, most of the hemodynamic parameters of more than or equal to 8/15 patients in PiCCO monitoring group were abnormal, and the abnormal proportion decreased later. Conclusions: On the basis of traditional monitoring indicators, the use of PiCCO monitoring technology combined with the patient's condition (without pursuing normal levels of the parameters) in guiding the fluid resuscitation in severe burn patients can reduce the usage of colloid and better improve tissue perfusion, with the resuscitation effect being better than conventional monitoring.

A novel method of trans-esophageal Doppler cardiac output monitoring utilizing peripheral arterial pulse contour with/without machine learning approach.

Transesophageal Doppler (TED) velocity in the descending thoracic aorta (DA) is used to track changes in cardiac output (CO). However, CO tracking by this method is hampered by substantial change in aortic cross-sectional area (CSA) or proportionality between blood flow to the upper and lower body. To overcome this, we have developed a new method of TED CO monitoring. In this method, TED signal is obtained primarily from the aortic arch (AA). Using AA velocity signal, CO (COAA-CSA) is estimated by compensating changes in the aortic CSA with peripheral arterial pulse contour. When AA cannot be displayed properly or when the quality of AA velocity signal is unacceptable, our method estimates CO (CODA-ML) from DA velocity signal first by compensating changes in the aortic CSA, and by compensating changes in the blood flow proportionality through a machine learning of the relation between the CSA-adjusted CO and a reference CO (COref). In 12 anesthetized dogs, we compared COAA-CSA and CODA-ML with COref measured by an ascending aortic flow probe under diverse hemodynamic conditions (COref changed from 723 to 7316ml·min-1). Between COAA-CSA and COref, concordance rate in the four-quadrant plot analysis was 96%, while angular concordance rate in the polar plot analysis was 91%. Between CODA-ML and COref, concordance rate was 93% and angular concordance rate was 94%. Both COAA-CSA and CODA-ML demonstrated "good to marginal" tracking ability of COref. In conclusion, our method may allow a robust and reliable tracking of CO during perioperative hemodynamic management.

Maternal hemodynamic assessment by USCOM® device in the first trimester of pregnancy

Background Preeclampsia is a main obstetric disease and could be caused by the inability of the woman hemodynamic system to face the cardiovascular effort required by gestation. Objective The aim of the present study is to evaluate the correlation between maternal hemodynamic parameters detected by UltraSonic Cardiac Output Monitor (USCOM®) and ultrasound or biochemical parameters in women during the first-trimester screening of chromosomal abnormalities. Methods This was a prospective observational study with 162 women enrolled during the first-trimester ultrasound, recording demographic, biochemical and ultrasound data, including the pulsatility index of uterine arteries (UTPI). Hemodynamic indices were obtained using the USCOM® system. We also analyzed the outcomes of pregnancy of those women who delivered in our clinic. Results As for the correlation between biochemical and ultrasound parameters, pregnancy-associated plasma protein A (PAPP-A) relates inversely with the mean UTPI (r s −0.298, p < .001). We also reported a statistically significant correlation between the mean UTPI and the maternal haemodynamic parameters detected by USCOM® (higher values of mean UTPI are associated with lower values of indexed cardiac output, CO, and higher indexed peripheral resistances, TVR). When comparing women with higher UTPI and TVR or lower CO to patients who had regular values of these parameters, we noticed that between these groups there were significant differences in all the remaining hemodynamic parameters, including inotropy index and stroke volume, as well as in the biochemical values of PAPP-A. Analyzing postpartum data, if we combine the onset of hypertensive disorders and fetal growth restriction, the most predictive parameter is indexed TVR. Conclusion Our study confirmed the correlation between PAPP-A and placental function, expressed through the determination of the pulsatility index of the uterine arteries. Moreover, we found a clear correlation between biochemical markers, placental function and maternal hemodynamics, since the first trimester of pregnancy. The inclusion of maternal hemodynamic evaluation could be useful in the screening protocols of preeclampsia. If we combine the onset of hypertensive disorders and of fetal growth restriction, the most predictive parameter is indexed total vascular resistances.

Systemic Oxygen Utilization in Severe COVID-19 Respiratory Failure: A Case Series.

Management of hypoxemia in patients with severe COVID-19 respiratory failure is based on the guideline recommendations for specific SpO2 targets. However, limited data exist on systemic O2 utilization. The objective of this study was to examine systemic O2 utilization in a case series of patients with this disease. Between March 24, and April 9, 2020, 8 patients intubated for severe COVID-19 respiratory failure had near-simultaneous drawing of arterial blood gas (ABG), central venous blood gas (cVBG), and central venous oxygen saturation (ScvO2) at a mean of 6.1 days into hospitalization. Three patients were managed with indirect cardiac output (CO) monitoring by FloTrac sensor and Vigileo monitor (Edwards Lifesciences, Irvine, CA). The oxygen extraction index (OEI; SaO2-ScvO2/SaO2) and oxygen extraction fraction (OEF; CaO2-CvO2/CaO2 ≥ 100) were calculated. Values for hyperoxia (ScvO2 ≥ 90%), normoxia (ScvO2 71-89%), and hypoxia (ScvO2 ≤ 70%) were based on the literature. Mean values were calculated. The mean partial pressure of oxygen (PaO2) was 102 with a mean fraction of inspired O2 (FiO2) of 44%. One patient was hyperoxic with a reduced OEI (17%). Five patients were normoxic, but 2 had a reduced OEF (mean 15.9%). Two patients were hypoxic but had increased systemic O2 utilization based on OEF or OEI. In select patients with severe COVID-19 respiratory failure, O2 delivery (DO2) was found to exceed O2 utilization. SpO2 targets based on systemic O2 utilization may help in reducing oxygen toxicity, especially in the absence of anaerobic metabolism. Further data are needed on the prevalence of systemic O2 utilization in COVID-19. Garg RK, Kimbrough T, Lodhi W, DaSilva I. Systemic Oxygen Utilization in Severe COVID-19 Respiratory Failure: A Case Series. Indian J Crit Care Med 2021;25(2):215-218.

278 Assessing effects of lateral tilt on cardiac output using a Non-invasive technique

Aortocaval compression (ACC), or supine hypotension syndrome, may lead to adverse fetal outcomes secondary to changes in maternal hemodynamics. Lateral tilt has been advocated to address ACC. We aim to determine the maternal position with the least effect on maternal hemodynamics. Term pregnant women scheduled for induction of labor were first placed in semi-recumbent (baseline), followed by supine, 15o and 30 o left lateral tilt (LLT), each for 20 minutes period, after which hemodynamic parameters were measuring using non-invasive cardiac output monitor NICOM. Friedman ANOVA with Dunn’s test multiple comparison test were used for analysis. P<0.05 was considered statistically significant. Forty subjects were included (Table). Cardiac index (CI) significantly increased in the supine position compared with baseline (median [range]: 3.8 [2.8-5.2] vs 4.2 [2.9-5.9] L/min/m2). CI also increased in 15o and 30 o left lateral tilt but did not reach statistical significance (Figure). Compared with baseline, stroke volume index (SVI) significantly increased (baseline: 43.7 [31.0-65.0]; supine: 49.5 [34.0-77.0]; 15o LLT: 49.8 [34.0-70.0] and 30o LLT: 49.9 [32.0-66.0] ml/m2; P<0.05 for all; Figure) while maternal heart rate significantly decreased in all 3 positions (baseline: 88 [70-106], supine: 85[63-99], 15o LLT: 81 [61-98] and 30o LLT: 80.0 [61-96] bpm; P<0.05 for all). Stroke volume variation (SVV) significantly decreased in all 3 positions (baseline: 12.9 [8.0-18.0], supine: 11.6 [7.0-17.0], 15o LLT: 11.6 [6.0-20.0] and 30o LLT 11.5 [7.0-20.0] %; P<0.05 for all). Subgroup analysis for BMI above or below 30 Kg/m2 showed similar results. Compared to semi-recumbent position, supine followed by left tilt position led to improvements in maternal hemodynamic parameters. The improvement in SVV, a measure of hypovolemia, indicates an increase in venous return and upper-right shift in the Frank-Starling curve. It is best to avoid semi-recumbent position in term pregnancies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)