cardiac output
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Author(s):  
Yuki Nakano ◽  
Jun Takeshita ◽  
Kazuya Tachibana

2022 ◽  
Vol 11 (2) ◽  
pp. 317
Author(s):  
Birgid Gonska ◽  
Dominik Buckert ◽  
Johannes Mörike ◽  
Dominik Scharnbeck ◽  
Johannes Kersten ◽  
...  

Aortic stenosis (AS) is the most frequent degenerative valvular disease in developed countries. Its incidence has been constantly rising due to population aging. The diagnosis of AS was considered straightforward for a very long time. High gradients and reduced aortic valve area were considered as “sine qua non” in diagnosis of AS until a growing body of evidence showed that patients with low gradients could also have severe AS with the same or even worse outcome. This completely changed the paradigm of AS diagnosis and involved large numbers of parameters that had never been used in the evaluation of AS severity. Low gradient AS patients may present with heart failure (HF) with preserved or reduced left ventricular ejection fraction (LVEF), associated with changes in cardiac output and flow across the aortic valve. These patients with low-flow low-gradient or paradoxical low-flow low-gradient AS are particularly challenging to diagnose, and cardiac output and flow across the aortic valve have become the most relevant parameters in evaluation of AS, besides gradients and aortic valve area. The introduction of other imaging modalities in the diagnosis of AS significantly improved our knowledge about cardiac mechanics, tissue characterization of myocardium, calcium and inflammation burden of the aortic valve, and their impact on severity, progression and prognosis of AS, not only in symptomatic but also in asymptomatic patients. However, a variety of novel parameters also brought uncertainty regarding the clinical relevance of these indices, as well as the necessity for their validation in everyday practice. The aim of this review is to summarize the prevalence of HF in patients with severe AS and elaborate on the diagnostic challenges and advantages of comprehensive multimodality cardiac imaging to identify the patients that may benefit from surgical or transcatheter aortic valve replacement, as well as parameters that may help during follow-up.


Author(s):  
Georg Schmücker ◽  
Christof Burgdorf ◽  
Jan-Henrik Blohm ◽  
Mathias Bugno ◽  
Kathrin Meyer ◽  
...  

Abstract Objectives Cardiac output (CO) measurements employing the direct Fick principle represent the gold standard in right-sided heart catheterization (RHC). The current widespread approach in hemodynamic workup however uses the indirect Fick principle with assumed values for oxygen uptake (VO2) leading to incorrect CO values in up to 25% of patients. We have tested a contemporary breath-by-breath gas analyzer that allows precise real-time measurements of VO2 with appropriate time and effort to serve the direct Fick principle. Methods By means of a small and mobile metabolic cart assembled with widely used components of a standard spiroergometer, we performed bedside measurements of individual VO2. In 33 unselected, consecutive patients with various indications for RHC we compared CO values derived from indirect vs. direct Fick calculations. Results In 28 of the 33 patients, VO2 measurements were completed with a plausible dataset within a median of 3.2 (interquartile range 2.8–6.2) min. In nine of the 28 patients, CO values based on measured VO2 values differed by more than 20% from CO calculations based on assumed VO2 values with value deviations scattering over a broad range in both directions (maximally +52% to minimally −46%). Conclusions The bedside measurement of VO2 for gold standard CO determination is technically feasible within a few min and can thus be easily included in any RHC protocol. As modern therapy for numerus indications demand a precise upfront measurement of hemodynamics, our method might help to correctly identify patients for costly therapies.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Zijun Chen ◽  
Jieshu Zhou ◽  
Li Wan ◽  
Han Huang

Abstract Background Compared with singleton pregnancy, twin gestation is featured by a greater increase in cardiac output. Therefore, norepinephrine might be more suitable than phenylephrine for maintaining blood pressure during cesarean section for twins, as phenylephrine causes reflex bradycardia and a resultant decrease in cardiac output. This study was to determine whether norepinephrine was superior to phenylephrine in maintaining maternal hemodynamics during cesarean section for twins. Methods Informed consent was obtained from all the patients before enrollment. In this double-blinded, randomized clinical trial, 100 parturients with twin gestation undergoing cesarean section with spinal anesthesia were randomized to receive prophylactic norepinephrine (3.2 μg/min) or phenylephrine infusion (40 μg/min). The primary outcome was the change of heart rate and blood pressure during the study period. The secondary outcomes were to compare maternal complications, neonatal outcomes, Apgar scores and umbilical blood acid-base status between the two vasopressors. Results There was no significant difference observed for the change of heart rate between two vasopressors. The mean standardized area under the curve of heart rate was 78 ± 12 with norepinephrine vs. 74 ± 11 beats/min with phenylephrine (mean difference 4.4, 95%CI − 0.1 to 9.0; P = .0567). The mean standardized area under the curve of systolic blood pressure (SBP) was significantly lower in parturients with norepinephrine, as the mean of differences in standardized AUC of SBP was 6 mmHg, with a 95% CI from 2 to 9 mmHg (P = .0013). However, requirements of physician interventions for correcting maternal hemodynamical abnormalities (temporary cessation of vasopressor infusion for reactive hypertension, rescuing vasopressor bolus for hypotension and atropine for heart rate less < 50 beats/min) and neonatal outcomes were also not significantly different between two vasopressors. Conclusion Infusion of norepinephrine was not associated with less overall decrease in heart rate during cesarean section for twins, compared with phenylephrine. Trial registration Chinese Clinical Trial Registry (ChiCTR1900021281).


Author(s):  
Nasia Sheikh ◽  
Aaron A. Phillips ◽  
Shaun Ranada ◽  
Matthew Lloyd ◽  
Karolina Kogut ◽  
...  

Background: Initial orthostatic hypotension (IOH) is defined by a large drop in blood pressure (BP) within 15 s of standing. IOH often presents during an active stand, but not with a passive tilt, suggesting that a muscle activation reflex involving lower body muscles plays an important role. To our knowledge, there is no literature exploring how sympathetic activation affects IOH. We hypothesized involuntary muscle contractions before standing would significantly reduce the drop in BP seen in IOH while increasing sympathetic activity would not. Methods: Study participants performed 4 sit-to-stand maneuvers including a mental stress test (serial 7 mental arithmetic stress test), cold pressor test, electrical stimulation, and no intervention. Continuous heart rate and beat-to-beat BP were measured. Cardiac output and systemic vascular resistance were estimated from these waveforms. Data are presented as mean±SD. Results: A total of 23 female IOH participants (31±8 years) completed the study. The drops in systolic BP following the serial 7 mental arithmetic stress test (−26±12 mm Hg; P =0.004), cold pressor test (−20±15 mm Hg; P <0.001), and electrical stimulation (−28±12 mm Hg; P =0.01) were significantly reduced compared with no intervention (−34±11 mm Hg). The drops in systemic vascular resistance following the serial 7 mental arithmetic stress test (−391±206 dyne×s/cm 5 ; P =0.006) and cold pressor test (−386±179 dyne×s/cm 5 ; P =0.011) were significantly reduced compared with no intervention (−488±173 dyne×s/cm 5 ). Cardiac output was significantly increased upon standing (7±2 L/min) compared with during the sit (6±1 L/min; P <0.001) for electrical stimulation. Conclusion: Sympathetic activation mitigates the BP response in IOH, while involuntary muscle contraction mitigates the BP response and reduces symptoms. Active muscle contractions may induce both of these mechanisms of action in their pretreatment of IOH. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03970551.


2022 ◽  
Author(s):  
Cornelis Slagt ◽  
Eduard Johannes Spoelder ◽  
Marijn Cornelia Theresia Tacken ◽  
Maartje Frijlink ◽  
Sjoerd Servaas ◽  
...  

Abstract Background: During the COVID-19 pandemic in The Netherlands, critically ill ventilated COVID-19 patients were transferred not only between hospitals by ambulance but also by the Helicopter Emergency Medical Service (HEMS). To date, little is known about the impact of helicopter transport on critically ill patients and COVID-19 patients in particular. This study was conducted to explore the impact of inter-hospital helicopter transfer on vital signs of mechanically ventilated severe COVID-19 intensive care patients, with special focus on take-off, midflight, and landing.Methods: All ventilated critically ill COVID-19 patients who were transported between April 2020 and June 2021 by the Dutch ‘Lifeliner 5’ HEMS team and who were fully monitored, including noninvasive cardiac output, were included in this study. Three 10-minute timeframes (take-off, midflight and landing) were defined for analysis. Continuous data on the vital parameters heart rate, peripheral oxygen saturation, arterial blood pressure, end-tidal CO2 and noninvasive cardiac output using electrical cardiometry were collected and stored at 1-minute intervals. Data were analydzed for differences over time within the timeframes using 1-way analysis of variance. Significant differences were checked for clinical relevance.Results: Ninety-eight patients were included in the analysis. During take-off, an increase was noticed in cardiac output (from 6.7 to 8.1 Lmin-1; P<0.0001), which was determined by a decrease in systemic vascular resistance (from 1068 to 750 dyne·s·cm−5, P<0.0001) accompanied by an increase in stroke volume (from 92.0 to 110.2 ml, P<0.0001). Other parameters were unchanged during take-off and mid-flight. During landing, cardiac output and stroke volume slightly decreased (from 7.9 to 7.1 Lmin-1, P<0.0001 and from 108.3 to 100.6 ml, P<0.0001, respectively), and total systemic vascular resistance increased (P<0.0001). Though statistically significant, the found changes were small and not clinically relevant to the medical status of the patients as judged by the attending physicians.Conclusions: Interhospital helicopter transfer of ventilated intensive care patients with COVID-19 can be performed safely and does not result in clinically relevant changes in vital signs.This study was assessed by the medical ethical committee Arnhem-Nijmegen, the Netherlands (identifier 2021-7313). The committee waived the need for informed consent. The study was registered at www.trialregister.nl (identifier NL9307).


Critical Care ◽  
2022 ◽  
Vol 26 (1) ◽  
Author(s):  
Yoann Zerbib ◽  
Alexis Lambour ◽  
Julien Maizel ◽  
Loay Kontar ◽  
Bertrand De Cagny ◽  
...  

Abstract Background In the context of acute respiratory distress syndrome (ARDS), the response to lung recruitment maneuvers (LRMs) varies considerably from one patient to another and so is difficult to predict. The aim of the study was to determine whether or not the recruitment-to-inflation (R/I) ratio could differentiate between patients according to the change in lung mechanics during the LRM. Methods We evaluated the changes in gas exchange and respiratory mechanics induced by a stepwise LRM at a constant driving pressure of 15 cmH2O during pressure-controlled ventilation. We assessed lung recruitability by measuring the R/I ratio. Patients were dichotomized with regard to the median R/I ratio. Results We included 30 patients with moderate-to-severe ARDS and a median [interquartile range] R/I ratio of 0.62 [0.42–0.83]. After the LRM, patients with high recruitability (R/I ratio ≥ 0.62) presented an improvement in the PaO2/FiO2 ratio, due to significant increase in respiratory system compliance (33 [27–42] vs. 42 [35–60] mL/cmH2O; p < 0.001). In low recruitability patients (R/I < 0.62), the increase in PaO2/FiO2 ratio was associated with a significant decrease in pulse pressure as a surrogate of cardiac output (70 [55–85] vs. 50 [51–67] mmHg; p = 0.01) but not with a significant change in respiratory system compliance (33 [24–47] vs. 35 [25–47] mL/cmH2O; p = 0.74). Conclusion After the LRM, patients with high recruitability presented a significant increase in respiratory system compliance (indicating a gain in ventilated area), while those with low recruitability presented a decrease in pulse pressure suggesting a drop in cardiac output and therefore in intrapulmonary shunt.


2022 ◽  
Author(s):  
Chiara Sonnino ◽  
Luciano Frassanito ◽  
Alessandra Piersanti ◽  
Pietro Paolo Giuri ◽  
Bruno Antonio Zanfini ◽  
...  

Abstract Background: Left uterine displacement (LUD) has been questioned as an effective strategy to prevent aortocaval compression after spinal anesthesia (SA) for cesarean delivery (CD). We tested if LUD has a significant impact on cardiac output (CO) in patients undergoing CD under SA during continuous non-invasive hemodynamic monitoring.Methods: Forty-six patients were included in the final analysis. We considered 4 timepoints of 5 minutes each: T1=baseline with LUD; T2=baseline without LUD; T3=after SA with LUD; T4=after SA without LUD. LUD was then repositioned for CD. Primary outcome was to test if CO decreased from T3 to T4. We also compared CO between T1 and T2 and other hemodynamic variables: mean, systolic and diastolic blood pressure (respectively MAP, SAP and DAP), heart rate (HR), stroke volume (SV), stroke volume variation (SVV), pulse pressure variation (PPV), contractility (dP/dt), dynamic arterial elastance (Eadyn) at the different timepoints. Data on fetal Apgar scores and umbilical arterial and venous pH were collected.Results: CO did not vary from T3 to T4 [CO mean difference -0.02 L/min [95% CI -0.88 to 0.82; p=1]. No significant variation was registered for any variable at any timepoint. Conclusions: LUD did not show a significant impact on CO during continuous hemodynamic monitoring after SA for CD.Trial registration: (retrospectively registered on 03/12/2021) NCT05143684.


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