Risk Factors for Radial-to-Femoral Artery Pressure Gradient in Patients Undergoing Cardiac Surgery With Cardiopulmonary Bypass

Instantaneous Right Ventricular to Pulmonary Artery Systolic Pressure Difference in Cardiac Surgery: A Retrospective and Prospective Cohort Study

BACKGROUND

During cardiac surgery, right ventricular outflow tract obstruction (RVOTO) is defined as an instantaneous pressure difference ≥ 6 mm Hg between right ventricular systolic pressure (RVSP) and pulmonary artery systolic pressure (PASP), for ≥ 5 minutes. Risk factors for RVOTO remain poorly understood. This cohort study was designed to evaluate the incidence, characteristics, and outcomes of the patients who experienced RVOTO.

METHODS

Instantaneous pressure difference between RVSP and PASP was measured by means of a pulmonary artery catheter with a right ventricular port during cardiac surgery from a retrospective (n = 295) and a prospective (n = 105) cohort.

RESULTS

From the retrospective and prospective cohorts, respectively, incidence of RVOTO was 30.2% and 36.2% before cardiopulmonary bypass (CPB) initiation and 43.7% and 47.6% after CPB separation. Before CPB initiation, patients with RVOTO had higher cardiac output (4.2 ± 1.5 vs 3.8 ± 1.1 L/min; P = 0.033) and received more inhaled epoprostenol (79% vs 61%; P = 0.005) and inotropes (66% vs 51%; P = 0.016) compared with those without RVOTO. After CPB separation, patients with RVOTO had higher heart rate (62 ± 15 vs 58 ± 13 beats/min; P = 0.011), cardiac output (4.1 ± 1.4 vs 3.7 ± 1.1 L/min; P = 0.003), and CPB duration (90 ± 45 vs 77 ± 30 min, P = 0.014), had lower fluid balance (758 ± 1123 vs 1063 ± 1089 mL; P = 0.021), and were more exposed to intratracheal milrinone (12% vs 4%; P = 0.015) compared with those without RVOTO. The time with persistent organ dysfunction (TPOD) at 28 days after surgery was similar among patients who had an RVOTO event, before CPB initiation or after CPB separation, compared with those who did not.

CONCLUSIONS

RVOTO is common in cardiac surgery. However, it is not associated with longer TPOD.

Hemodynamic Monitoring In The Cardiac Surgical Patient: Comparison of Three Arterial Catheters

OBJECTIVE

Systemic systolic (SAP) and mean (MAP) arterial pressure monitoring is the cornerstone in hemodynamic management of the cardiac surgical patient, and the radial artery is the most common site of catheter placement. The present study compared 3 different arterial line procedures. It is hypothesized that a 20-G 12.7- cm catheter inserted into the radial artery will be equal to a 20-G 12.7- cm angiocath placed in the brachial artery, and superior to a 20-G 5.00 cm angiocath placed in the radial artery.

DESIGN

A prospective randomized control study was performed.

SETTING

Single academic university hospital.

PARTICIPANTS

Adult patients ≥18 years old undergoing nonemergent cardiac surgery using cardiopulmonary bypass (CPB).

INTERVENTIONS

After approval by the Rhode Island Hospital institutional review board, a randomized prospective control study to evaluate 3 different peripheral intraarterial catheter systems was performed: (1) Radial Short (RS): 20-G 5- cm catheter; (2) Radial Long (RL): 20-G 12- cm catheter; and (3) Brachial Long (BL): 20-G 12- cm catheter.

MEASUREMENTS AND RESULTS

Gradients between central aortic and peripheral catheters (CA-P) were compared and analyzed before CPB and 2 and 10 minutes after separation from CPB. The placement of femoral arterial lines and administration of vasoactive medications were recorded. After exclusions, 67 BL, 61 RL, and 66 RS patients were compared. Before CPB, CA-P SAP and MAP gradients were not significant among the 3 groups. Two minutes after CPB, the CA-P SAP gradient was significant for the RS group (p = 0.005) and insignificant for BL (p = 0.47) and RL (p = 0.39). Two-group analysis revealed that CA-P SAP gradients are similar between BL and RL (p = 0.84), both of which were superior to RS (p = 0.02 and p = 0.04, respectively). At 10 minutes after CPB, the CA-P SAP gradient for RS remained significant (p = 0.004) and similar to the gradient at 2 minutes. The CA-P SAP gradients increased from 2 to 10 minutes for BL (p = 0.13) and RL (p = 0.06). Two minutes after CPB, the CA-P MAP gradients were significant for the BL (p = 0.003), RL (p < 0.0001), and RS (p < 0.0001) groups. Two-group analysis revealed that the CA-P MAP gradients were lower for the BL group compared with the RL (p = 0.054) and RS (p< 0.05) groups. Ten minutes after CPB, the CA-P MAP gradients in the RL and RS groups remained significant (p < 0.0001) and both greater than the BL group (p = 0.002). A femoral arterial line was placed more frequently in the RS group (8/66 = 12.1%) than in the RL group (3/61 = 4.9%) and the BL group (2/67 = 3.0%). Vasopressin was administered significantly more frequently in the RS group.

CONCLUSION

Regarding CA-P SAP gradients, the RL group performed equally to the BL group, both being superior to RS. Regarding CA-P MAP gradients, BL was superior to RL and RS. Clinically, femoral line placement and vasopressin administration were fewer for the BL and RL groups when compared with the RS group. This study demonstrated the benefits of a long (12.7 cm) 20- G angiocath placed in the radial artery.

Central Versus Peripheral Arterial Pressure Monitoring in Patients Undergoing Cardiac Surgery: A Prospective Observational Study

OBJECTIVE

The aortic-to-radial arterial pressure gradient is described during and after cardiopulmonary bypass (CPB), and can lead to underestimating arterial blood pressure. The authors hypothesized that central arterial pressure monitoring would be associated with lower norepinephrine requirements than radial arterial pressure monitoring during cardiac surgery.

DESIGN

An observational prospective cohort with propensity score analysis.

SETTING

At a tertiary academic hospital's operating room and intensive care unit (ICU).

PARTICIPANTS

A total of 286 consecutive adult patients undergoing cardiac surgery with CPB (central group: 109; radial group: 177) were enrolled and analyzed.

INTERVENTIONS

To explore the hemodynamic effect of the measurement site, the authors divided the cohort into 2 groups according to a femoral/axillary (central group) or radial (radial group) site of arterial pressure monitoring.

MEASUREMENT AND MAIN RESULTS

The primary outcome was the intraoperative amount of norepinephrine administered. Secondary outcomes included norepinephrine-free hours and ICU-free hours at postoperative day 2 (POD2). A logistic model with propensity score analysis was built to predict central arterial pressure monitoring use. The authors compared demographic, hemodynamic, and outcomes data before and after adjustment. Central group patients had a higher European System for Cardiac Operative Risk Evaluation. (EuroSCORE) compared to the radial group-7.9 ± 14.0 versus 3.8 ± 7.0, p < 0.001. After adjustment, both groups had similar patient EuroSCORE and arterial blood pressure levels. Intraoperative norepinephrine dose regimens were 0.10 ± 0.10 µg/kg/min in the central group and 0.11 ± 0.11 µg/kg/min in the radial group (p = 0.519). Norepinephrine-free hours at POD2 were 38 ± 17 hours versus 33 ± 19 hours in central and radial groups, respectively (p = 0.034). The ICU-free hours at POD2 were greater in the central group: 18 ± 13 hours versus 13 ± 13 hours, p = 0.008. Adverse events were less frequent in the central group than in the radial group-67% versus 50%, p = 0.007.

CONCLUSIONS

No differences in the norepinephrine dose regimen were found according to the arterial measurement site during cardiac surgery. However, norepinephrine use and length of stay in the ICU were shorter, and adverse events were decreased when central arterial pressure monitoring was used.

Risk factors for femoral-to-radial artery pressure gradient after weaning from cardiopulmonary bypass: a historical cohort study

PURPOSE

After weaning from cardiopulmonary bypass (CPB), the radial artery pressure is frequently lower than the central pressure as reflected by femoral pressure. This discrepancy may cause improper blood pressure management. In this study, we aimed to evaluate the risk factors related to developing a significant postbypass femoral-to-radial pressure gradient, including the incidence of complications related to femoral pressure monitoring.

METHODS

From January 2017 to May 2021, we studied consecutive adult cardiovascular surgical patients undergoing CPB in a historical cohort study. Patients were divided into two groups according to developing a significant femoral-to-radial pressure gradient, which was defined as a difference of ≥ 25 mm Hg for systolic pressure or ≥ 10 mm Hg for mean pressure, lasting ≥ 5 minutes for 30 minutes after CPB weaning. Factors associated with a significant pressure gradient and femoral pressure monitoring-related complications were analyzed.

RESULTS

Among 2,019 patients, 677 (34%) showed a significant postbypass femoral-to-radial pressure gradient. Multivariable logistic regression analysis revealed the following factors related to the pressure gradient development: age (adjusted odds ratio [aOR] for an increase in 10 years, 1.09; 95% confidence interval [CI], 1.04 to 1.09; P < 0.001), body surface area (BSA) (aOR for an increase in 1 m2, 0.12; 95% CI, 0.07 to 0.21; P < 0.001), aortic cross-clamping time (aOR for an increase in 30 minutes, 1.05; 95% CI, 1.03 to 1.08; P < 0.001), and intraoperative epinephrine use (aOR, 1.55; 95% CI, 1.23 to 1.95; P < 0.001). The femoral pressure monitoring-related complications were observed in 11/2,019 (0.5%) patients.

CONCLUSION

Our study showed that old age, smaller BSA, prolonged aortic cross-clamping time, and intraoperative epinephrine use were associated with developing a significant postbypass femoral-to-radial pressure gradient in cardiovascular surgery. Considering monitoring-related complications occurred very infrequently, it might be helpful to monitor both radial and femoral pressure simultaneously in patients with these risk factors for appropriate blood pressure management. Nevertheless, further studies are needed to confirm our findings because our results are limited by a retrospective design and residual confounding factors.

Femoral Pulse Pressure Variation Is Not Interchangeable with Radial Pulse Pressure Variation during Living Donor Liver Transplantation

The radial artery is commonly used as the site measuring pulse pressure variation (PPV) during surgery. Accurate measurement of circulating blood volume and timely interventions to maintain optimal circulating blood volume is important to deliver sufficient oxygen to tissues and organs. It has not rather than never studied in patients undergoing liver transplantation whether PPV measured at peripheral sites, such as the radial artery, do represent central PPV for evaluating blood volume. In this retrospective study, 51 liver transplant recipients were enrolled. The two PPVs had been automatically recorded every minute in electrical medical records. A total 1878 pairs of the two PPVs were collected. The interchangeability of PPV measured at the radial and the femoral artery was analyzed by using the Bland−Altman plot, four-quadrant plot, Cohen’s kappa (k), and receiver operating curve. The bias and limits of agreement of the two PPVs were −1.3% and −8.8% to 6.2%, respectively. The percentage error was 75%. The concordance rate was 65%. The Kappa of PPV-radial determining whether PPV-femoral was >13% or ≤13% was 0.64. We found that PPV-radial is not interchangeable with PPV-femoral during liver transplantation. Additionally, PPV-radial failed to reliably track changes of PPV-femoral. Lastly, the clinical decision regarding blood volume status (depletion or not) is significantly different between the two PPVs. Therefore, PPV-femoral may help maintain blood volume circulating to major organs including the newly transplanted liver graft for liver transplant recipients.

Radial-to-femoral pressure gradient quantification in cardiac surgery

Background

A radial-to-femoral pressure gradient (RFPG) can occur in roughly one-third of cardiac surgical patients. Such a gradient has been associated with smaller stature and potentially smaller radial artery diameter. We hypothesized that preoperative radial artery diameter could be a predictor of RFPG. We also investigated the clinical impact of using a femoral versus a radial arterial catheter in terms of vasoactive support.

Methods

Using ultrasound, we measured the bilateral radial artery diameters of 160 cardiac surgical patients. All arterial pressure values were continuously recorded. Significant RFPG was defined as ≥25 mm Hg in systolic and/or ≥10 mm Hg in mean arterial pressure. One hundred and forty-nine additional patients were used to validate the impact of our observations.

Results

Using 78,013 pressure datapoints in 129 patients, 34.8% of patients had an RFPG with a mean duration of 54 ± 48 minutes. Patients with a radial artery diameter <1.8 mm were more likely to have an RFPG (n = 14 [48.3%] vs 12 [22.2%]; P = .042). Patients with only a radial catheter received more phenylephrine (P = .016) despite undergoing shorter and less complex procedures. In the validation cohort, similar observations were made, and patients with a radial artery catheter received a longer duration of vasoactive support in the intensive care unit.

Conclusions

A significant RFPG occurs in one-third of cardiac surgical patients and in 48% of those with a radial artery diameter <1.8 mm. The use of a single radial arterial catheter instead of dual radial and femoral catheters was associated with greater vasopressor requirements in the operating room and in the intensive care unit. We do not recommend the use of a single radial artery catheter in cardiac surgery.

Non-invasive detection of a femoral-to-radial arterial pressure gradient in intensive care patients with vasoactive agents

BACKGROUND

In patient requiring vasopressors, the radial artery pressure may underestimate the true central aortic pressure leading to unnecessary interventions. When using a femoral and a radial arterial line, this femoral-to-radial arterial pressure gradient (FR-APG) can be detected. Our main objective was to assess the accuracy of non-invasive blood pressure (NIBP) measures; specifically, measuring the gradient between the NIBP obtained at the brachial artery and the radial artery pressure and calculating the non-invasive brachial-to-radial arterial pressure gradient (NIBR-APG) to detect an FR-APG. The secondary objective was to assess the prevalence of the FR-APG in a targeted sample of critically ill patients.

METHODS

Adult patients in an intensive care unit requiring vasopressors and instrumented with a femoral and a radial artery line were selected. We recorded invasive radial and femoral arterial pressure, and brachial NIBP. Measurements were repeated each hour for 2 h. A significant FR-APG (our reference standard) was defined by either a mean arterial pressure (MAP) difference of more than 10 mmHg or a systolic arterial pressure (SAP) difference of more than 25 mmHg. The diagnostic accuracy of the NIBR-APG (our index test) to detect a significant FR-APG was estimated and the prevalence of an FR-APG was measured and correlated with the NIBR-APG.

RESULTS

Eighty-one patients aged 68 [IQR 58-75] years and an SAPS2 score of 35 (SD 7) were included from which 228 measurements were obtained. A significant FR-APG occurred in 15 patients with a prevalence of 18.5% [95%CI 10.8-28.7%]. Diabetes was significantly associated with a significant FR-APG. The use of a 11 mmHg difference in MAP between the NIBP at the brachial artery and the MAP of the radial artery led to a specificity of 92% [67; 100], a sensitivity of 100% [95%CI 83; 100] and an AUC ROC of 0.93 [95%CI 0.81-0.99] to detect a significant FR-APG. SAP and MAP FR-APG correlated with SAP (r2 = 0.36; p < 0.001) and MAP (r2 = 0.34; p < 0.001) NIBR-APG.

CONCLUSION

NIBR-APG assessment can be used to detect a significant FR-APG which occur in one in every five critically ill patients requiring vasoactive agents.

A proposed algorithm for combining transcranial Doppler ultrasound monitoring with cerebral and somatic oximetry: a case report

PURPOSE

Transcranial Doppler (TCD) ultrasound is a non-invasive monitor of cerebral blood velocity that can be used intraoperatively. The purpose of this report is to describe how different patterns seen on TCD can help identify the cause of cerebral desaturation when near-infrared spectroscopy (NIRS) oximetry is used concomitantly.

CLINICAL FEATURES

A 69-yr-old male patient undergoing coronary revascularisation and aortic valve replacement developed perioperative complications that were detected using a combination of transtemporal TCD of the middle cerebral artery along with cerebral and somatic NIRS. Initial brain desaturation was secondary to hypocapnia during which TCD-derived blood velocity and somatic NIRS values remained unchanged. After the procedure, a second episode of brain desaturation occurred secondary to a technical issue with the aortic valve prosthesis requiring a return to cardiopulmonary bypass (CPB); there were no high-intensity transient signals (HITS) on TCD. Brain desaturation occurred a third time following the second attempt to separate from CPB at which time TCD detected a significant amount of HITS suggesting air emboli that were associated with acute right ventricular dysfunction; there was also a reduction in somatic NIRS.

CONCLUSIONS

Combining TCD with cerebral NIRS allows for the rapid identification of three different mechanisms of brain desaturation. An algorithm is proposed to help identify the origin of NIRS cerebral desaturation. Prospective clinical trials are needed to investigate potential benefits of multimodal brain monitoring and its impact on short and/or long-term clinical outcomes.

Preliminary Experience Using Diastolic Right Ventricular Pressure Gradient Monitoring in Cardiac Surgery

OBJECTIVES

Right ventricular (RV) dysfunction in cardiac surgery is associated with increased mortality and morbidity and difficult separation from cardiopulmonary bypass (DSB). The primary objective of the present study was to describe the prevalence and characteristics of patients with abnormal RV diastolic pressure gradient (PG). The secondary objective was to explore the association among abnormal diastolic PG and DSB, postoperative complications, high central venous pressure (CVP), and high RV end-diastolic pressure (RVEDP).

DESIGN

Retrospective and prospective validation study.

SETTING

Tertiary care cardiac institute.

PARTICIPANTS

Cardiac surgical patients (n=374) from a retrospective analysis (n=259) and a prospective validation group (n=115).

INTERVENTION

RV pressure waveforms were obtained using a pulmonary artery catheter with a pacing port opened at 19 cm distal to the tip of the catheter. Abnormal RV diastolic PG was defined as >4 mmHg. Both elevated RVEDP and high CVP were defined as >16 mmHg.

MEASUREMENTS AND MAIN RESULTS

From the retrospective and validation cohorts, 42.5% and 48% of the patients had abnormal RV diastolic PG before cardiac surgery, respectively. Abnormal RV diastolic PG before cardiac surgery was associated with higher EuroSCORE II (odds ratio 2.29 [1.10-4.80] v 1.62 [1.10-3.04]; p = 0.041), abnormal hepatic venous flow (45% v 29%; p = 0.038), higher body mass index (28.9 [25.5-32.5] v 27.0 [24.9-30.5]; p = 0.022), pulmonary hypertension (48% v 37%; p = 0.005), and more frequent DSB (32% v 19%; p = 0.023). However, RV diastolic PG was not an independent predictor of DSB, whereas RVEDP (odds ratio 1.67 [1.09-2.55]; p = 0.018) was independently associated with DSB. In addition, RV pressure monitoring indices were superior to CVP in predicting DSB.

CONCLUSION

Abnormal RV diastolic PG is common before cardiac surgery and is associated with a higher proportion of known preoperative risk factors. However, an abnormal RV diastolic PG gradient is not an independent predictor of DSB in contrast to RVEDP.