Gastrointestinal bleeding following pediatric cardiac bypass: An insight from the national inpatient sample

Abstract

Background:

Gastrointestinal (GI) bleeding is a rare but severe complication following pediatric cardiac bypass surgery. Despite advancements in pediatric cardiac surgery, postoperative complications like GI bleeding remain a critical concern. This study investigates its incidence, risk factors, and outcomes using the National Inpatient Sample (NIS).

Methods:

A retrospective, cross-sectional analysis was conducted using the NIS database (2016–2020). Pediatric patients (0–18 years) undergoing cardiac bypass surgery were identified via International Classification of Diseases, Tenth Revision, Procedure Coding System (ICD-10-PCS) codes, with postoperative GI bleeding defined by ICD-10-CM diagnosis codes. Weighted analyses accounted for the complex survey design, and multivariable logistic regression identified independent predictors.

Results:

Among 24,275 weighted cases, 110 (0.45%) experienced postoperative gastrointestinal (GI) bleeding. Significant predictors included cardiac surgery (OR = 5.7, 95% CI: 3.75–8.69, P < 0.001), larger hospital bed size, and teaching hospital status. Calendar year and hospital region were also associated with bleeding risk (95.5% of cases). Mortality was significantly higher in patients with GI bleeding (36.4% vs. 0.3%, P < 0.001).

Conclusions:

Postoperative GI bleeding is a life-threatening complication in pediatric cardiac bypass surgery. Identifying high-risk patients and optimizing perioperative management are crucial. Future research should focus on elucidating underlying mechanisms and developing targeted interventions to improve outcomes.

INTRODUCTION

Pediatric cardiac surgery has made remarkable progress over the past few decades, significantly improving survival rates and quality of life for children with congenital heart disease (CHD). However, postoperative complications remain a critical concern, affecting both short-term recovery and long-term outcomes.[1,2] Among these complications, gastrointestinal (GI) bleeding is a relatively rare but potentially severe adverse event that can occur following cardiopulmonary bypass (CPB) in pediatric patients.[3,4] GI bleeding may arise due to a combination of factors, including systemic inflammatory response syndrome (SIRS), coagulopathy, ischemia-reperfusion injury, and the use of anticoagulants during CPB.[5,6,7,8]

The pathophysiology of postoperative GI bleeding in pediatric cardiac surgery patients is multifactorial. CPB induces a systemic inflammatory response, leading to endothelial dysfunction and altered hemostasis, which may predispose patients to mucosal injury and bleeding.[7] Prolonged CPB times, hypothermia, and reperfusion injury can exacerbate GI ischemia, further increasing the risk of bleeding.[6,8] In pediatric populations, immature physiology and smaller vascular volumes make them particularly vulnerable to these complications.[5,6] Additionally, the use of extracorporeal membrane oxygenation (ECMO) and other mechanical support devices can further compromise GI perfusion, contributing to the risk of bleeding.[9,10]

Other studies have identified specific risk factors, such as preoperative anemia, low platelet counts, and prolonged mechanical ventilation, as predictors of postoperative GI bleeding.[11,12,13] These findings highlight the importance of preoperative optimization and vigilant postoperative monitoring in high-risk patients.

Despite its clinical significance, the exact incidence and underlying mechanisms of postoperative GI bleeding in pediatric cardiac surgery remain poorly defined. This knowledge gap underscores the need for further research to identify predictive factors, optimize perioperative management strategies, and improve patient outcomes. Future studies should focus on elucidating the role of inflammatory markers, coagulation profiles, and GI perfusion in the development of this complication. Additionally, the development of standardized protocols for risk assessment and prevention could significantly reduce the burden of GI bleeding in this vulnerable population.

METHODS

Study design and data source

This study utilized a retrospective, cross-sectional design to analyze the incidence and risk factors of postoperative GI bleeding in pediatric patients undergoing cardiac bypass surgery. The data were extracted from the national inpatient sample (NIS), which is part of the Healthcare Cost and Utilization Project sponsored by the Agency for Healthcare Research and Quality. The NIS is the largest all-payer inpatient care database in the United States, providing weighted estimates representative of the U.S. population.

The dataset included hospitalizations of pediatric patients (ages 0–18 years) who underwent cardiac bypass surgery between 2016 and 2020. The study period was chosen to ensure sufficient sample size and to capture recent trends in pediatric cardiac surgery practices.

Study population and definitions

The study population consisted of pediatric patients who underwent cardiac bypass surgery during the study period. Cases were identified using International Classification of Diseases, Tenth Revision, Procedure Coding System (ICD-10-PCS) codes for cardiopulmonary bypass procedures. Postoperative GI bleeding was defined based on ICD-10-CM diagnosis codes related to upper or lower GI bleeding occurring during the same hospitalization as the cardiac surgery.

Statistical analysis

Data analysis was performed using Stata/SE version 15.0 (StataCorp LLC, College Station, Texas, USA), accounting for the complex survey design of the NIS to produce nationally representative estimates. All analyses incorporated sampling weights, strata, and primary sampling units to adjust for clustering and weighting.

Baseline characteristics were summarized using weighted counts and percentages for categorical variables. Continuous variables were reported as means ± standard deviations (SDs) or medians with interquartile ranges, as appropriate.

Chi-square tests were used to compare categorical variables between patients with and without postoperative GI bleeding. Univariate Logistic Regression: Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each independent variable to assess its association with postoperative GI bleeding. A multivariable model was constructed to identify independent predictors of GI bleeding after adjusting for confounding variables.

RESULTS

Among 24,275 pediatric patients undergoing cardiac bypass surgery, 110 (0.5%) developed postoperative gastrointestinal (GI) bleeding. Baseline demographic and hospital characteristics stratified by GI bleeding status are summarized in Table 1.

Table 1.

Baseline characteristics for gastrointestinal tract bleeding status after pediatric cardiac bypass surgery

Variable		GIT bleeding=0 (n=24,000)		GIT bleeding=1 (n=110)		Total (n=24,275)		P
Died during hospitalization
Yes		70 (0.3)		40 (36.4)		110		<0.001
Primary expected payer
Medicare		40 (0.2)		0		40		0.69
Medicaid		12,000 (50.0)		50 (45.5)		12,050
Private insurance		9775 (40.7)		45 (40.9)		9820
Self-pay		335 (1.4)		0		335
No charge		15 (0.1)		0		15
Other		1540 (6.4)		15 (13.6)		1555
Race
White		12,000 (50.0)		30 (27.3)		12,030		0.13
Black		3355 (14.0)		20 (18.2)		3375
Hispanic		5345 (22.3)		50 (45.5)		5395
Asian or Pacific Islander		1155 (4.8)		5 (4.5)		1160
Native American		205 (0.9)		0		205
Other		1785 (7.4)		5 (4.5)		1790
Calendar year
2016		4815 (20.1)		25 (22.7)		4840		0.66
2017		4940 (20.6)		10 (9.1)		4950
2018		4685 (19.5)		25 (22.7)		4710
2019		5090 (21.2)		20 (18.2)		5110
2020		4635 (19.3)		30 (27.3)		4665
Median household income quartile
Lowest		6990 (29.1)		40 (36.4)		7030		0.86
Second quintile		6700 (27.9)		30 (27.3)		6730
Third quintile		5895 (24.6)		20 (18.2)		5915
Highest		4580 (19.1)		20 (18.2)		4600
Hospital bed size
Small		3220 (13.4)		5 (4.5)		3225		0.43
Medium		5870 (24.5)		25 (22.7)		5895
Large		15,000 (62.5)		80 (72.7)		15,080
Hospital teaching status
Nonteaching		20 (0.1)		0		20		0.08
Rural teaching		160 (0.7)		5 (4.5)		165
Urban teaching		24,000 (100.0)		105 (95.5)		24,105
Hospital region
Northeast		3500 (14.6)		20 (18.2)		3520		0.5
Midwest		5435 (22.7)		10 (9.1)		5445
South		9070 (37.8)		50 (45.5)		9120
West		6160 (25.7)		30 (27.3)		6190

GIT: Gastrointestinal tract

Patients who experienced GI bleeding had a markedly higher in-hospital mortality compared to those without bleeding (36.4% vs. 0.3%, p < 0.001). No significant differences were observed in primary expected payer distribution, calendar year, household income quartile, hospital bed size, or hospital region. However, patients with GI bleeding were more likely to be Hispanic (45.5% vs. 22.3%) and less frequently White (27.3% vs. 50.0%), though these differences did not reach statistical significance (p = 0.13). A higher proportion of bleeding cases occurred in large hospitals (72.7% vs. 62.5%), and in urban teaching hospitals (95.5% vs. 100.0%), but these associations were not statistically significant (p = 0.43 and p = 0.08, respectively).

Multivariable regression analysis identified several independent predictors of postoperative GI bleeding [Table 2]. Cardiac surgery itself remained a strong predictor of GI bleeding (OR 5.7, 95% CI 3.75–8.69, p < 0.001). Additional significant predictors included calendar year (OR 0.95, 95% CI 0.93–0.98, p < 0.001), hospital bed size (OR 1.25, 95% CI 1.19–1.31, p < 0.001), hospital teaching status (OR 3.1, 95% CI 2.76–3.50, p < 0.001), and hospital region (OR 1.05, 95% CI 1.01–1.09, p = 0.013). Race, primary expected payer, and median household income quartile were not associated with bleeding risk in the adjusted models.

Table 2.

Regression analysis for predictors of post procedure gastrointestinal tract bleeding

Variable		Odds ratio		95% CI		P-value
Univariate
Cardiac surgery		7.18		4.71–10.93		<0.001
Multivariable
Cardiac surgery		5.7		3.75–8.69		<0.001
Primary expected payer		0.99		0.94–1.05		0.847
Race		0.99		0.97–1.02		0.514
Calendar year		0.95		0.93–0.98		<0.001
Median household income quartile		0.99		0.96–1.02		0.443
Hospital bed size		1.25		1.19–1.31		<0.001
Hospital teaching status		3.1		2.76–3.50		<0.001
Hospital region		1.05		1.01–1.09		0.013

DISCUSSION

GI bleeding following pediatric cardiac bypass surgery is a rare yet severe complication that poses significant challenges in postoperative care.[4] While advancements in pediatric cardiac surgery have improved survival rates for children with CHD, complications such as GI bleeding remain critical concerns.[2] This study, utilizing the NIS, contributes to the growing body of literature on this topic by providing insights into the incidence, risk factors, and outcomes associated with postoperative GI bleeding.

The findings from our study align with previous research highlighting the multifactorial nature of GI bleeding in pediatric cardiac surgery patients.[3] A retrospective study by Li et al. identified prolonged CPB times, hypothermia, and reperfusion injury as key contributors to GI ischemia and subsequent bleeding.[5] Similarly, Spiezia et al. emphasized the role of coagulopathy and endothelial dysfunction induced by CPB in predisposing patients to postoperative hemorrhage.[6] These pathophysiological mechanisms are further exacerbated in pediatric populations due to their immature physiology and limited compensatory reserves.[14]

Our study found that cardiac surgery itself was a significant independent predictor of GI bleeding (OR = 5.7, 95% CI: 3.75–8.69, P < 0.001). This observation corroborates findings from Li et al., who reported that children undergoing complex cardiac repairs were at a higher risk of developing GI bleeding compared to those undergoing simpler procedures.[5] The complexity of the surgical intervention likely influences the extent of SIRS, coagulation disturbances, and organ perfusion abnormalities, all of which contribute to the development of GI bleeding.[4,5]

Hospital characteristics, including teaching status and bed size, emerged as notable risk factors in our analysis. Urban teaching hospitals and larger institutions reported higher incidences of GI bleeding, possibly reflecting the concentration of more complex cases in these settings.

Demographic variables, such as ethnicity and socioeconomic status, showed trends toward associations with GI bleeding, although these differences did not reach statistical significance after multivariable adjustment. Hispanic ethnicity was overrepresented among patients experiencing post cardiac mortality, echoing observations from other studies that ethnic minorities may face disparities in healthcare access and outcomes.[15] Lower median household income quartiles also trended toward higher risks, suggesting that socioeconomic factors could influence preoperative optimization and postoperative recovery.[13] Future research should explore these relationships further to address potential inequities in care.

The pathophysiology of postoperative GI bleeding involves a complex interplay of inflammatory, hemostatic, and perfusion-related factors. Knežević et al. provided a comprehensive review of endothelial dysfunction in cardiac surgery patients, emphasizing its role in promoting vascular leakage and mucosal injury.[7] Mallick et al. highlighted the detrimental effects of ischemia-reperfusion injury on intestinal integrity, particularly during CPB.[8] These processes, combined with the use of anticoagulants and mechanical circulatory support devices like ECMO, create a perfect storm for GI bleeding.[8,10]

Dalton et al. examined bleeding and thrombosis in children receiving ECMO, identifying platelet dysfunction and altered coagulation profiles as major contributors.[10] These findings underscore the importance of meticulous anticoagulation management in preventing both thrombotic and hemorrhagic complications.[10] Our study supports these conclusions, as evidenced by the high mortality rate (36.4%) among patients with GI bleeding, indicating the severity of underlying systemic derangements.

Despite advancements in understanding postoperative GI bleeding mechanisms, significant knowledge gaps persist. Although inflammatory markers and coagulation profiles are associated with its development, their specific roles and predictive value need further exploration. Additional data on CPB duration, aortic cross-clamp (ACC) times, intraoperative hemodynamics, coagulation profiles, and inflammatory markers are crucial to identify the direct causes of GI bleeding. The pediatric literature demonstrates that panels incorporating natriuretic peptides (BNP, NT-proBNP, proANP), high-sensitivity troponin T, pro-adrenomedullin, and other biomarkers measured pre- or early postoperatively can identify children at increased risk for adverse outcomes—including cardiac events, need for respiratory orinotropic support, and mortality—after cardiac surgery, with combined biomarker approaches offering superior predictive value compared to single markers alone.[4,15,16,17,18] Incorporating advanced imaging techniques, such as Doppler ultrasound or near-infrared spectroscopy, could enhance our ability to monitor GI perfusion dynamically and intervene proactively.[19,20]

Standardized protocols for risk assessment and prevention are urgently needed. Current guidelines lack specificity for pediatric populations, necessitating tailored approaches that account for age-related physiological differences. Collaborative efforts between surgeons, intensivists, hematologists, and gastroenterologists will be essential in addressing these gaps and translating findings into clinical practice.

This study analyzed the extensive and diverse dataset provided by the NIS, enabling nationally representative estimates and capturing a wide range of patient demographics and hospital characteristics. However, inherent limitations of administrative data must be acknowledged. Coding inaccuracies, lack of detailed clinical information, and inability to account for unmeasured confounders may introduce biases. Additionally, the design precludes causal inference, necessitating caution in interpreting associations as definitive cause-and-effect relationships.

CONCLUSIONS

Postoperative GI bleeding in pediatric cardiac surgery is a major issue needing focus from clinicians, researchers, and policymakers. Identifying high-risk patients, improving perioperative care, and creating evidence-based guidelines can reduce this complication and improve outcomes. Cross-specialty collaboration is key to implementing effective practices and ensuring equitable care. More research is needed on surgical complexity and its impact. While surgical complexity and hospital factors contribute to GI bleeding risk, future studies should use standardized scores (e.g. RACHS, STAT) and operative metrics such as CPB and ACC times to enhance risk assessment and prevention strategies.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.