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Published on: September 15, 2023
Impact of Low Hematocrit on On-Pump Coronary Artery Bypass Graft Surgery Outcomes
A M Nayeem Parvez1, Redoy Ranjan2,3,4, Sheikh Muhammad Bin Faruque5
1Cardiovascular Surgery, Impulse Hospital, Dhaka, BGD.
Insights
Low hematocrit levels (≤22%) during cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) surgery are linked to increased adverse outcomes. Maintaining higher hematocrit levels during CPB is recommended to improve patient recovery and reduce complications.
Area of Science:
- Cardiology
- Hematology
- Surgical Outcomes
Background:
- Low hematocrit is common during cardiopulmonary bypass (CPB) in on-pump coronary artery bypass grafting (CABG).
- The impact of hematocrit levels ≤22% during CPB on adverse outcomes in CABG patients is assessed.
Purpose of the Study:
- To evaluate the association between low hematocrit levels (≤22%) during CPB and adverse outcomes in on-pump CABG patients.
- To identify predictors of postoperative complications in a Bangladeshi population.
Main Methods:
- A comparative cross-sectional study of 350 age- and sex-matched patients undergoing on-pump CABG.
- Patients were divided into two groups: hematocrit ≤22% (Group A) and >22% (Group B) during CPB.
- Multivariate logistic regression analysis was used to determine independent predictors of adverse outcomes.
Main Results:
- Group A (hematocrit ≤22%) showed significantly longer mechanical ventilation, higher blood transfusion needs, and longer ICU stays.
- Postoperative complications were more frequent in Group A, including acute kidney injury (AKI), deep sternal infection, and in-hospital mortality.
- Low hematocrit (≤22%) during CPB was independently associated with increased blood transfusions, longer ICU stays, AKI, deep sternal infection, and mortality.
Conclusions:
- Hematocrit levels of 22% or lower during CPB are associated with increased morbidity and mortality after on-pump CABG.
- Maintaining hematocrit levels above 22% during CPB is recommended to improve postoperative outcomes.
Background:
Low hematocrit level is a hematological problem that is frequently encountered during cardiopulmonary bypass (CPB) in patients undergoing on-pump coronary artery bypass grafting (CABG). This study aimed to assess the impact of low hematocrit levels (≤22%) during CPB on the adverse outcomes of on-pump CABG in a large-scale, age- and sex-adjusted Bangladeshi population.
Materials And Methods:
This comparative cross-sectional study recruited 350 patients, age- and sex-matched, and divided them into two groups: Group A, comprising 175 patients with a hematocrit level of ≤22% on CPB, and Group B, comprising 175 patients with a hematocrit level of >22% on CPB. Univariate analysis curtailed the risk patterns, whereas multivariate logistic regression (LR) analysis observed independent predictors of postoperative adverse outcomes.
Results:
The mean age was similar between Group A and Group B (57.82 ± 6.32 vs. 56.97 ± 6.49 years, P = 0.57), with a male predominance in both groups (135 (77.1%) vs. 130 (74.3%), χ² = 0.24, P = 0.78). Univariate analysis showed that Group A had longer mechanical ventilation hours (15.09 ± 2.64 vs. 12.57 ± 3.90, P = 0.002), required more blood transfusions (3.67 ± 1.48 vs. 1.94 ± 0.79 units, P = 0.001), and had longer ICU stays (5.05 ± 0.96 vs. 3.45 ± 1.12 days, P = 0.001) compared with Group B. Postoperative complications were also more frequent in Group A, including acute kidney injury (AKI) (34.3% vs. 14.3%, χ² = 17.96, P < 0.001), deep sternal infection (8.6% vs. 2.9%, χ² = 4.29, P = 0.03), and in-hospital mortality (5.7% vs. 2.9%, χ² = 1.11, P = 0.02). In age- and sex-adjusted multivariate LR analysis, a hematocrit level ≤22% during CPB was significantly associated with adverse outcomes: higher blood transfusion requirements (odds ratio (OR) = 5.95, 95% CI 1.21-9.83, P = 0.001), longer ICU stays (OR = 3.27, 95% CI 1.06-4.24, P = 0.02), AKI (OR = 3.13, 95% CI 1.19-8.14, P = 0.01), deep sternal infection (OR = 1.18, 95% CI 1.31-6.24, P = 0.04), and in-hospital mortality (OR = 1.56, 95% CI 1.17-7.28, P = 0.03). A receiver operating characteristic (ROC) curve analysis yielded an area under the ROC curve of 0.756 (95% CI 0.65-0.86; P < 0.001) for predicting adverse outcomes, with 80.0% sensitivity and 45.0% specificity at a 22% hematocrit threshold.
Conclusions:
Hematocrit levels of 22% or lower during CPB are associated with increased morbidity and mortality following on-pump CABG. Maintaining hematocrit levels above 22% during CPB is therefore recommended to improve postoperative outcomes.
