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Association Between Ionized Calcium Concentrations During Weaning From Cardiopulmonary Bypass and Postoperative Low
Yasutaka Hamai1,2, Yohei Okada1,3, Shinya Ito2,4
1From the Department of Preventive Services, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Insights
Ionized calcium (iCa) levels during cardiopulmonary bypass (CPB) weaning impact cardiovascular surgery outcomes. Both low and high iCa concentrations were linked to a higher risk of low cardiac output syndrome (LCOS).
Area of Science:
- Cardiology
- Anesthesiology
- Critical Care Medicine
Background:
- Ionized calcium (iCa) is vital for myocardial contractility during cardiovascular surgery.
- Hypocalcemia is common during cardiopulmonary bypass (CPB), yet its link to clinical outcomes is understudied.
- This study investigated the association between iCa levels during CPB weaning and postoperative outcomes.
Purpose of the Study:
- To evaluate the relationship between ionized calcium (iCa) levels at the time of weaning from cardiopulmonary bypass (CPB) and the incidence of low cardiac output syndrome (LCOS).
Main Methods:
- A multicenter retrospective study included 2,382 adult patients undergoing cardiovascular surgery with CPB.
- Patients were categorized into four groups based on iCa levels during CPB weaning (≤1.05, 1.05-1.13, 1.13-1.24, >1.24 mmol L-1).
- Low cardiac output syndrome (LCOS) was defined by criteria including mechanical circulatory support use, low cardiac index, or intensive use of inotropes.
Main Results:
- The overall incidence of LCOS was 21% (501 patients).
- Compared to the standard iCa group, patients in the low iCa group (iCa ≤ 1.05 mmol L-1) had a significantly increased adjusted odds ratio for LCOS (1.45; P=.020).
- The moderate-high iCa group (1.13 < iCa ≤ 1.24 mmol L-1) also showed a significant increase in LCOS risk (adjusted OR 1.42; P=.046).
Conclusions:
- Both low and high ionized calcium (iCa) levels during cardiopulmonary bypass (CPB) weaning are associated with an elevated risk of postoperative low cardiac output syndrome (LCOS).
- Maintaining optimal iCa levels during this critical phase of cardiovascular surgery is crucial for improving patient outcomes.
Background:
Weaning from cardiopulmonary bypass (CPB) is a critical step in cardiovascular surgery. Although ionized calcium (iCa) plays a crucial role in myocardial contractility, and hypocalcemia commonly occurs during CPB, only a few studies have examined the association between iCa levels and clinical outcomes following CPB. This study aimed to evaluate whether iCa levels during CPB weaning were associated with clinical outcomes.
Methods:
This multicenter retrospective study was conducted in three Japanese hospitals. Adult patients (aged ≥ 18 years) who underwent cardiovascular surgery with CPB were included. Exposure was defined as iCa concentration during CPB weaning. The primary outcome was low cardiac output syndrome (LCOS) on ICU admission, which was determined when at least one of the following three criteria was met: (i) postoperative MCS use, (ii) cardiac index <2.0 L min-1 m-2, (iii) use of two or more inotropes (dopamine, dobutamine, adrenaline, and milrinone) at 1 hour following the end of the surgery. The patients were divided into four groups based on iCa quartile: low iCa group (iCa ≤ 1.05 mmol L-1), standard iCa group (1.05 < iCa ≤ 1.13 mmol L-1), moderate-high iCa group (1.13 < iCa ≤1.24 mmol L-1), and high iCa group (iCa > 1.24 mmol L-1). Multivariate logistic regression analyses were performed to calculate adjusted odds ratios (ORs) with 95% confidence intervals (CIs).
Results:
In total, 2,382 patients were included between September 2012 and December 2022. The median age was 70 years (IQR: 60-76 years), and 1,464 patients (61%) were men. The overall LCOS incidence was 501 cases (21%). Compared to the standard iCa group, the adjusted ORs for LCOS were 1.45 (95% CI, 1.06 to 1.99, P = .020) in the low iCa group, 1.42 (95% CI, 1.01 to 2.00, P = .046) in the moderate-high iCa group, and 1.36 (95% CI, 0.95 to 1.94, P = .094) in the high iCa group.
Conclusions:
Both low and high iCa levels at CPB weaning were associated with an increased risk of postoperative LCOS in patients undergoing cardiovascular surgery.
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