It remains unclear whether reduced myocardial contractility, venous dilation with decreased venous return, or arterial dilation with reduced systemic vascular resistance contribute most to hypotension after induction of general anesthesia. We sought to assess the relative contribution of various hemodynamic mechanisms to hypotension after induction of general anesthesia with sufentanil, propofol, and rocuronium. In this prospective observational study, we continuously recorded hemodynamic variables during anesthetic induction using a finger-cuff method in 92 non-cardiac surgery patients. After sufentanil administration, there was no clinically important change in arterial pressure, but heart rate increased from baseline by 11 (99.89% confidence interval: 7 to 16) bpm (P < 0.001). After administration of propofol, mean arterial pressure decreased by 23 (17 to 28) mmHg and systemic vascular resistance index decreased by 565 (419 to 712) dyn*s*cm−5*m2 (P values < 0.001). Mean arterial pressure was < 65 mmHg in 27 patients (29%). After propofol administration, heart rate returned to baseline, and stroke volume index and cardiac index remained stable. After tracheal intubation, there were no clinically important differences compared to baseline in heart rate, stroke volume index, and cardiac index, but arterial pressure and systemic vascular resistance index remained markedly decreased. Anesthetic induction with sufentanil, propofol, and rocuronium reduced arterial pressure and systemic vascular resistance index. Heart rate, stroke volume index, and cardiac index remained stable. Post-induction hypotension therefore appears to result from arterial dilation with reduced systemic vascular resistance rather than venous dilation or reduced myocardial contractility.

No abstract

Background Pulmonary 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. Methods We 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. Results The 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)%. Conclusion The 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.

The finger-cuff system CNAP (CNSystems Medizintechnik, Graz, Austria) allows non-invasive automated measurement of pulse pressure variation (PPVCNAP). We sought to validate the PPVCNAP-algorithm and investigate the agreement between PPVCNAP and arterial catheter-derived manually calculated pulse pressure variation (PPVINV). This was a prospective method comparison study in patients having neurosurgery. PPVINV was the reference method. We applied the PPVCNAP-algorithm to arterial catheter-derived blood pressure waveforms (PPVINV−CNAP) and to CNAP finger-cuff-derived blood pressure waveforms (PPVCNAP). To validate the PPVCNAP-algorithm, we compared PPVINV−CNAP to PPVINV. To investigate the clinical performance of PPVCNAP, we compared PPVCNAP to PPVINV. We used Bland–Altman analysis (absolute agreement), Deming regression, concordance, and Cohen's kappa (predictive agreement for three pulse pressure variation categories). We analyzed 360 measurements from 36 patients. The mean of the differences between PPVINV−CNAP and PPVINV was −0.1% (95% limits of agreement (95%-LoA) −2.5 to 2.3%). Deming regression showed a slope of 0.99 (95% confidence interval (95%-CI) 0.91 to 1.06) and intercept of −0.02 (95%-CI −0.52 to 0.47). The predictive agreement between PPVINV−CNAP and PPVINV was 92% and Cohen’s kappa was 0.79. The mean of the differences between PPVCNAP and PPVINV was −1.0% (95%-LoA−6.3 to 4.3%). Deming regression showed a slope of 0.85 (95%-CI 0.78 to 0.91) and intercept of 0.10 (95%-CI −0.34 to 0.55). The predictive agreement between PPVCNAP and PPVINV was 82% and Cohen’s kappa was 0.48. The PPVCNAP-algorithm reliably calculates pulse pressure variation compared to manual offline pulse pressure variation calculation when applied on the same arterial blood pressure waveform. The absolute and predictive agreement between PPVCNAP and PPVINV are moderate.

BACKGROUND: Cardiac output is an important hemodynamic variable and determines oxygen delivery. In contrast to blood pressure, cardiac output is rarely measured even in high-risk surgical patients, suggesting that clinicians consider blood pressure to be a reasonable indicator of systemic blood flow. However, the relationship depends on constant vascular tone and volume, both of which routinely vary during anesthesia and surgery. We therefore tested the hypothesis that there is no clinically meaningful correlation between mean arterial pressure and cardiac index in major abdominal surgery patients. METHODS: In this prospective observational study, we assessed the relationship between mean arterial pressure and cardiac index in 100 patients having major abdominal surgery under general anesthesia. RESULTS: The pooled within-patient correlation coefficient calculated using meta-analysis methods was r = 0.34 (95% confidence interval, 0.28-0.40). Linear regression using a linear mixed effects model of cardiac index on mean arterial pressure revealed that cardiac index increases by 0.014 L•min −1 •m −2 for each 1 mm Hg increase in mean arterial pressure. The 95% Wald confidence interval of this slope was 0.011 to 0.018 L•min −1 •m −2 •mm Hg −1 and thus within predefined equivalence margins of −0.03 and 0.03 L•min −1 •m −2 •mm Hg −1 , thereby demonstrating lack of clinically meaningful association between mean arterial pressure and cardiac index. CONCLUSIONS: There is no clinically meaningful correlation between mean arterial pressure and cardiac index in patients having major abdominal surgery. Intraoperative blood pressure is thus a poor surrogate for cardiac index. (Anesth Analg 2022;134:322-9) KEY POINTS• Question: What is the relationship between mean arterial pressure and cardiac index in patients having major abdominal surgery under general anesthesia? • Findings: There was no clinically meaningful correlation between mean arterial pressure and cardiac index in patients having major abdominal surgery. • Meaning: Mean arterial pressure should not be considered even a rough indicator of cardiac index. GLOSSARYCI = cardiac index; CO = cardiac output; MAP = mean arterial pressure; STROBE = Strenghtening the Reporting of Observational Studies in Epidemiology; SVR = systemic vascular resistance C ardiac output (CO) is an important hemodynamic variable because CO-together with arterial oxygen content-determines oxygen delivery. 1 CO-guided hemodynamic management may improve postoperative outcomes in high-risk surgical patients. 2,3

No abstract

BACKGROUND The effect of different methods for data sampling and data processing on the results of comparative statistical analyses in method comparison studies of continuous arterial blood pressure (AP) monitoring systems remains unknown. OBJECTIVE We sought to investigate the effect of different methods for data sampling and data processing on the results of statistical analyses in method comparison studies of continuous AP monitoring systems. DESIGN Prospective observational study. SETTING University Medical Center Hamburg-Eppendorf, Hamburg, Germany, from April to October 2019. PATIENTS 49 patients scheduled for neurosurgery with AP measurement using a radial artery catheter. MAIN OUTCOME MEASURES We assessed the agreement between continuous noninvasive finger cuff-derived (CNAP Monitor 500; CNSystems Medizintechnik, Graz, Austria) and invasive AP measurements in a prospective method comparison study in patients having neurosurgery using all beat-to-beat AP measurements (Methodall), 10-s averages (Methodavg), one 30-min period of 10-s averages (Method30), Method30 with additional offset subtraction (Method30off), and 10 30-s periods without (Methodiso) or with (Methodiso-zero) application of the zero zone. The agreement was analysed using Bland-Altman and error grid analysis. RESULTS For mean AP, the mean of the differences (95% limits of agreement) was 9.0 (−12.9 to 30.9) mmHg for Methodall, 9.2 (−12.5 to 30.9) mmHg for Methodavg, 6.5 (−9.3 to 22.2) mmHg for Method30, 0.5 (−9.5 to 10.5) mmHg for Method30off, 4.9 (−6.0 to 15.7) mmHg for Methodiso, and 3.4 (−5.9 to 12.7) mmHg for Methodiso-zero. Similar trends were found for systolic and diastolic AP. Results of error grid analysis were also influenced by using different methods for data sampling and data processing. CONCLUSION Data sampling and data processing substantially impact the results of comparative statistics in method comparison studies of continuous AP monitoring systems. Depending on the method used for data sampling and data processing, the performance of an AP test method may be considered clinically acceptable or unacceptable.

Pulse pressure variation (PPV) and cardiac output (CO) can guide perioperative fluid management. Capstesia (Galenic App, Vitoria-Gasteiz, Spain) is a mobile application for snapshot pulse wave analysis (PWAsnap) and estimates PPV and CO using pulse wave analysis of a snapshot of the arterial blood pressure waveform displayed on any patient monitor. We evaluated the PPV and CO measurement performance of PWAsnap in adults having major abdominal surgery. In a prospective study, we simultaneously measured PPV and CO using PWAsnap installed on a tablet computer (PPV PWAsnap , CO PWAsnap) and using invasive internally calibrated pulse wave analysis (ProAQT; Pulsion Medical Systems, Feldkirchen, Germany; PPV ProAQT , CO ProAQT). We determined the diagnostic accuracy of PPV PWAsnap in comparison to PPV ProAQT according to three predefined PPV categories and by computing Cohen's kappa coefficient. We compared CO ProAQT and CO PWAsnap using Bland-Altman analysis, the percentage error, and four quadrant plot/concordance rate analysis to determine trending ability. We analyzed 190 paired PPV and CO measurements from 38 patients. The overall diagnostic agreement between PPV PWAsnap and PPV ProAQT across the three predefined PPV categories was 64.7% with a Cohen's kappa coefficient of 0.45. The mean (± standard deviation) of the differences between CO PWAsnap and CO ProAQT was 0.6 ± 1.3 L min − 1 (95% limits of agreement 3.1 to − 1.9 L min − 1) with a percentage error of 48.7% and a concordance rate of 45.1%. In adults having major abdominal surgery, PPV PWAsnap moderately agrees with PPV ProAQT. The absolute and trending agreement between CO PWAsnap with CO ProAQT is poor. Technical improvements are needed before PWAsnap can be recommended for hemodynamic monitoring.