Abstract
Objective
To investigate the association between enteral nutrition (EN) timing and postoperative anion gap (AG) trajectory in ICU patients undergoing cardiac surgery.
Methods
Data were extracted from the MIMIC-IV database. Cardiac surgery patients receiving EN were classified into preoperative and postoperative groups according to whether EN was first recorded before or after surgery. Baseline comparability was assessed. AG levels at admission, within 24 h after surgery, and at discharge were compared, and multivariable linear regression and subgroup analyses were performed as exploratory analyses.
Results
Among 195 cardiac surgery patients, 83 had preoperative EN and 112 had postoperative EN records. Baseline illness severity was broadly similar between groups, although age, sex, alcohol use history, and diabetes prevalence differed. No significant between-group difference in admission AG was observed, whereas the preoperative EN group had lower AG at postoperative 24 h (15 [12, 17] vs. 17 [14, 19], P = 0.035) and at discharge (15 [13, 17] vs. 17 [13, 21], P = 0.027). EN timing remained associated with postoperative 24-hour and discharge AG in multivariable models. EN timing was not clearly associated with postoperative delirium, in-hospital mortality, or length of hospital stay. It was discharge-AG that positively correlated with in-hospital mortality.
Conclusions
Preoperative EN was associated with lower postoperative and discharge AG levels in this retrospective cohort. However, this metabolic signal did not translate into clear clinical outcome benefit, and the findings should be interpreted as hypothesis-generating because residual confounding by indication remains possible.
Keywords: Enteral nutrition, Cardiac surgery, ICU, Anion gap, MIMIC-IV
Introduction
Cardiovascular diseases are the leading cause of patient deaths worldwide, with approximately 17.5 million deaths annually, 80% of which occur in low-and middle-income countries [1]. Without effective prevention and treatment strategies, it is projected that by 2030, the number of deaths from cardiovascular diseases will reach 24 million [2]. Cardiac surgery remains an important treatment option for selected patients with advanced cardiovascular disease, and a subset of these patients require postoperative ICU care and careful nutritional management [3, 4]. Malnutrition is a critical factor influencing adverse outcomes and complications after cardiac surgery. The nutritional status and nutrient delivery during critical illness are closely linked to clinical outcomes, such as mortality, infection rates, and hospital stays [4]. Adequate energy intake is crucial for the disease process and the recovery of critically ill patients. However, there is currently no consensus on the importance of nutritional support for patients undergoing cardiac surgery.
In addition to postoperative complications, patients who have undergone cardiac surgery are also frequently affected by acid-base imbalances and electrolyte disturbances. Research has shown that perioperative hyperlactatemia and decreased lactate clearance rate are predictive factors for Clostridium difficile infection in patients after cardiac surgery [5]. Maintaining metabolic homeostasis and physiological functions is crucial for acid-base balance, with the anion gap (AG) being a key indicator for assessing and diagnosing acid-base metabolic disorders. Studies have confirmed [6] that the serum AG level at admission is positively correlated with the duration of ICU stay and overall hospitalization in patients undergoing cardiac surgery; furthermore, postoperative AG levels are significantly associated with in-hospital mortality, 90-day mortality, and 4-year mortality risk. AG has become a predictive factor for prognosis and complications in patients with various diseases, including cardiac surgery [7–9].
Most existing studies have focused on the importance of nutritional support in reducing postoperative complications and improving survival rates in surgical patients. However, evidence regarding the timing of enteral nutrition and postoperative acid-base status in cardiac surgery ICU patients remains limited. In this retrospective study using the MIMIC-IV database, we evaluated whether preoperative versus postoperative EN timing was associated with postoperative AG trajectory. Given the observational nature of the database, this analysis was intended to be hypothesis-generating rather than to infer a treatment effect.
Methods
Research samples
The data of this study were obtained from the large open-access intensive care database MIMIC-IV (Medical Information Mart for Intensive Care). This study has been approved by the Ethics Committee of our hospital. As this study is a retrospective study, informed consent is not required.
The inclusion criteria for this study were as follows: all patients underwent surgery, had a first ICU admission, were aged > 18 years, and had records of enteral nutrition (EN). Patients were excluded if ICU stay duration was < 2 days or if they died within 2 days of ICU admission, because serial assessment required admission, postoperative 24-hour, and discharge measurements with a sufficiently documented ICU course. Patients with missing measurements of anion gap, lactate, and blood glucose at admission, within 24 h after surgery, or at discharge were also excluded. The patient selection process is presented in Fig. 1. Finally, a total of 195 cardiac surgery patients were included in the main analysis.
Fig. 1.
A flowchart of patient inclusion/exclusion
Data acquisition
The MIMIC-IV data were obtained using SQL, and we extracted age, sex, BMI, admission type, heart rate, respiratory rate, systolic blood pressure, diastolic blood pressure, illness severity markers (GCS, OASIS, SAPS II, SOFA, and CCI), alcohol use history, smoking history, and history of hypertension, chronic kidney disease, and diabetes. We also collected acid-base balance and nutrition related indicators including AG, lactate (mmol/L), blood glucose (mg/dL), and Geriatric Nutritional Risk Index (GNRI) levels at admission, within 24 h after surgery, and at discharge. Albumin (g/L), body weight (kg), and height (m) at admission and discharge were used to calculate the GNRI, with GNRI = 1.489×albumin + 41.7×[body weight/(22×height2)], and GNRI < 98 indicating malnutrition. BMI was categorized into four groups: underweight (< 18.5), normal (18.5–24.9), overweight (24.9–29.9), and obese (≥ 30). In addition, we collected 3 clinical outcomes data including postoperative delirium, length of hospital stay, and in-hospital mortality.
All patients were assigned to preoperative and postoperative EN groups. Preoperative EN was defined as EN first recorded before surgery, whereas postoperative EN was defined as EN first recorded after surgery. In MIMIC-IV database, consistent information on EN indication, exact formula selection, and the clinical rationale for initiating preoperative EN was unavailable and therefore could not be analyzed.
Statistical analysis
Statistical analysis was conducted using SPSS. As most quantitative variables were not normally distributed, they are reported as medians and quartiles, whereas categorical variables are reported as counts and percentages. The Mann-Whitney U test was used to compare quantitative variables between two groups, and the chi-square test was used to compare categorical variables. Linear regression analyses were performed to examine the association between EN timing and AG levels after adjustment for potential confounders. Covariates included in the multivariable models were clinically relevant factors, and collinearity was assessed using the variance inflation factor, with variables showing a variance inflation factor > 5 removed. The correlations of EN timing and AG levels at postoperative 24 h and discharge with 3 clinical outcomes indicators (postoperative delirium, in-hospital mortality, and length of hospital stay) were also explored. Subgroup analyses were considered exploratory because several strata contained limited sample sizes. P < 0.05 was considered statistically significant.
Results
Baseline data
This study included 195 cardiac surgery patients who received enteral nutrition during hospitalization, including 83 patients in the preoperative EN group and 112 patients in the postoperative EN group. Baseline characteristics are summarized in Table 1. Compared with the postoperative EN group, the preoperative EN group was younger (64 [54, 72] vs. 68 [57, 76], P = 0.038), included a higher proportion of men (69.9% vs. 55.4%, P = 0.039), had more recorded alcohol-use history (13.3% vs. 3.6%, P = 0.012), and had a higher prevalence of diabetes (51.8% vs. 32.1%, P = 0.006). BMI, admission type, vital signs, GCS, OASIS, SAPS II, SOFA, and CCI were otherwise similar between groups (all P > 0.05).
Table 1.
Baseline characteristics of cardiac surgery patients by EN timing
| Variable | Preoperative EN (n = 83) | Postoperative EN (n = 112) | P value |
|---|---|---|---|
| Age, years | 64 [54, 72] | 68 [57, 76] | 0.038 |
| BMI, kg/m2 | 29.1 [24.8, 32.9] | 27.5 [23.9, 31.2] | 0.212 |
| Heart rate, bpm | 88 [70, 105] | 87 [73, 100] | 0.824 |
| Respiratory rate, breaths/min | 20 [16, 25] | 20 [16, 24] | 0.872 |
| Systolic blood pressure, mmHg | 109 [93, 130] | 107 [93, 119] | 0.728 |
| Diastolic blood pressure, mmHg | 56 [46, 71] | 57 [49, 67] | 0.881 |
| GCS score | 15 [15, 15] | 15 [15, 15] | 0.295 |
| OASIS score | 36 ± 9 | 36 ± 8 | 0.807 |
| SAPS II score | 445 ± 15 | 47 ± 13 | 0.398 |
| SOFA score | 3 [0, 5] | 3 [1, 5] | 0.514 |
| CCI score | 7 [4, 9] | 6 [5, 8] | 0.542 |
| Male sex, n (%) | 58 (69.9%) | 62 (55.4%) | 0.039 |
| Admission type, n (%) | 0.686 | ||
| Urgent | 33 (39.8%) | 38 (33.9%) | |
| Emergency | 22 (26.5%) | 31 (27.7%) | |
| Other | 28 (33.7%) | 43 (38.4%) | |
| No alcohol use, n (%) | 72 (86.7%) | 108 (96.4%) | 0.012 |
| No smoking history, n (%) | 78 (94.0%) | 106 (94.6%) | 0.842 |
| No hypertension, n (%) | 57 (68.7%) | 66 (58.9%) | 0.163 |
| No chronic kidney disease, n (%) | 43 (51.8%) | 65 (58.0%) | 0.387 |
| No diabetes, n (%) | 40 (48.2%) | 76 (67.9%) | 0.006 |
Association between EN timing and acid-base balance in cardiac surgery patients
Subsequent analyses focused on the association between EN timing and acid-base balance in cardiac surgery patients. As shown in Table 2, admission AG, lactate, glucose, and GNRI did not differ between the preoperative and postoperative EN groups.
Table 2.
Differences in acid-base balance indicators between preoperative and postoperative EN groups in cardiac surgery patients
| Time point | Pre-op EN | Post-op EN | Z | P | |
|---|---|---|---|---|---|
| At admission | AG | 17 [14, 19] | 17 [15, 21] | -1.143 | 0.253 |
| lactic acid | 1.7 [1.3, 2.1] | 1.8 [1.4, 2.4] | -0.760 | 0.447 | |
| glucose | 155 [125, 221] | 163 [125, 237] | -0.415 | 0.678 | |
| GNRI | 56.9 [47.5, 64.0] | 52.9 [47.9, 70.6] | -0.366 | 0.714 | |
| Postoperative 24 h | AG | 15 [12, 17] | 17 [14, 19] | -2.110 | 0.035 |
| lactic acid | 1.4 [1.1, 1.9] | 1.6 [1.3, 2.4] | -1.411 | 0.158 | |
| glucose | 155 [125, 221] | 163 [125, 237] | -0.415 | 0.678 | |
| At discharge | AG | 15 [13, 17] | 17 [13, 21] | -2.210 | 0.027 |
| lactic acid | 1.3 [1.2, 1.6] | 1.3 [1.1, 1.7] | -0.220 | 0.826 | |
| glucose | 128 [95, 148] | 125 [105, 148] | -0.429 | 0.668 | |
| GNRI | 51.8 [42, 61.9] | 54.1 [47.3, 75.5] | -1.266 | 0.205 |
AG, anion gap; EN, enteral nutrition; GNRI, nutritional risk index
However, the preoperative EN group had lower AG within 24 h after surgery (15 [12, 17] vs. 17 [14, 19], P = 0.035) and at discharge (15 [13, 17] vs. 17 [13, 21], P = 0.027), whereas lactate, glucose, and GNRI remained similar. These findings suggested an association between EN timing and postoperative AG trajectory rather than evidence of a direct treatment effect.
We also summarized the AG trends over time in preoperative and postoperative EN groups, respectively (Fig. 2). The results showed that in the preoperative EN group, the AG level was relatively high at admission, but the overall AG level had remained at the normal level after the operation and at discharge. In the postoperative EN group, the AG level remained at a relatively high level throughout the overall stage. Overall, the AG in the postoperative EN group was higher than that in the preoperative EN group, and the fluctuations were greater.
Fig. 2.
AG trends over time in preoperative and postoperative EN groups. The data were presented with median and quartiles
Further, we explored the association between EN timing and AG levels at postoperative 24 h and at discharge. Line regression analysis (Table 3) showed that EN timing was significantly associated with AG levels at 24 h post-surgery (β = 0.204, P = 0.044) and at discharge (β = 0.235, P = 0.017). After adjusting for relevant variables, EN timing remained associated with AG levels at both time points (Models 2 and 3, all P < 0.05).
Table 3.
Association analysis between EN timing and AG levels in cardiac surgery patients
| Postoperative 24-hour AG levels [Dependent variable] | AG levels at discharge [Dependent variable] |
|||
|---|---|---|---|---|
| β (95%CI) | P | β (95%CI) | P | |
| All patients | ||||
| Model 1 | 0.204 [0.048, 3.538] | 0.044 | 0.235 [0.464, 4.725] | 0.017 |
| Model 2 | 0.276 [0.387, 4.382] | 0.020 | 0.302 [0.829, 5.778] | 0.010 |
| Model 3 | 0.330 [0.717, 4.967] | 0.010 | 0.284 [0.490, 5.730] | 0.021 |
| Subgroups | ||||
| Gender | ||||
| Male (n = 120) | 0.239 [-0.143, 4.232] | 0.066 | 0.320 [0.847, 5.986] | 0.010 |
| Female (n = 75) | 0.183 [-1.452, 5.024] | 0.271 | 0.067 [-3.391, 5.077] | 0.698 |
| Age | ||||
| ≤ 67 (n = 103) | 0.188 [-0.844, 4.478] | 0.176 | 0.329 [0.886, 7.296] | 0.013 |
| > 67 (n = 92) | 0.228 [-0.540, 4.024] | 0.131 | 0.087 [-1.938, 3.493] | 0.567 |
| BMI status | ||||
| Underweight (n = 9) | -0.228 [-32.690, 28.023] | 0.772 | -0.672 [-19.654, 6.654] | 0.214 |
| Normal (n = 24) | -0.430 [-8.054, 2.454] | 0.248 | -0.232 [-6.182, 3.382] | 0.519 |
| Overweight (n = 42) | 0.617 [2.430, 7.799] | 0.001 | 0.442 [0.918, 10.267] | 0.021 |
| Obese (n = 69) | 0.256 [-0.808, 5.604] | 0.138 | 0.320 [-0.111, 7.455] | 0.057 |
Model 1: no adjustment
Model 2: adjusting for age, gender and BMI
Model 3: adjusting for age, gender, BMI, history of myocardial infarction, diabetes, chronic kidney disease, and surgical history
AG, anion gap; EN, enteral nutrition; MI, myocardial infarction
We also performed subgroup analyses to assess their association stratified by age, gender, and BMI categories (Table 3). It should be noted that these analyses should be framed as exploratory due to its small sample sizes. The results showed that associations between EN timing and AG level at discharge were mainly observed in male patients, those aged 67 years or younger, and those with overweight (all P < 0.05). Because several strata were small, these estimates should be interpreted cautiously.
Correlation of EN timing and AG levels with clinical outcomes
Finally, we investigated the relationship between EN timing and clinical outcomes. The results (Table 4) indicated that preoperative versus postoperative EN timing was not clearly associated with postoperative delirium (P = 0.836), length of hospital stay (P = 0.066), or in-hospital mortality (P = 0.678).
Table 4.
Differences in clinical outcomes between preoperative and postoperative EN groups in cardiac surgery patients
| Preoperative EN | Postoperative EN | χ2 | P | ||
|---|---|---|---|---|---|
| Postoperative delirium | No | 72 (36.9%) | 96 (49.2%) | 0.043 | 0.836 |
| Yes | 11 (5.6%) | 16 (8.2%) | |||
| In-hospital mortality | No | 55 (28.2%) | 71 (36.4%) | 0.172 | 0.678 |
| Yes | 28 (14.4%) | 41 (21.0%) | |||
| Length of hospital stay | ≤ 28 days | 48 (24.6%) | 79 (40.5) | 0.388 | 0.066 |
| > 28 days | 35 (17.9%) | 33 (16.9) |
EN, enteral nutrition
We also explored the correlation of AG level postoperative 24-hour and at discharge with three clinical outcomes. The results showed that only AG level at discharge significantly positively correlated with the in-hospital mortality (Fig. 3A, cor = 0.513, P < 0.001), and the death group had higher AG levels compared with the survival group (Fig. 3B, median AG level: 20 vs. 15, P < 0.001); it was not related to the postoperative delirium and length of hospital stay (all P > 0.05). However, no significant correlation was observed between AG levels postoperative 24-hour and any of the study outcomes (all P > 0.05).
Fig. 3.
The correlation between AG level and clinical outcomes in cardiac surgery patients. (A) Spearman correlation analysis. (B) The difference in AG level at discharge between the alive and death groups
Discussion
Acid-base imbalance is common in critically ill patients. Various indicators, such as lactate, pH, bicarbonate, and AG, are widely used in clinical settings to assess acid-base balance [10]. In this retrospective cohort of cardiac surgery ICU patients who received EN, preoperative EN timing was associated with lower AG at postoperative 24 h and at discharge. Although the association between EN timing and AG levels was observed, these findings should be interpreted cautiously. In MIMIC-IV, EN timing is unlikely to represent a controlled intervention and may instead reflect perioperative trajectory, clinical stability, or treatment pathway. Accordingly, confounding by indication remains a major concern, and preoperative EN may function partly as a surrogate marker rather than a causal exposure.
Cardiac dysfunction is common among patients undergoing heart surgery, potentially leading to postoperative low cardiac output syndrome, which can increase the postoperative mortality rate. Previous studies have reported that AG levels are closely linked to cardiac function [11], with higher AG levels indicating poorer clinical classification of coronary heart disease and cardiac function. In this study, patients were provided with EN before surgery, and their postoperative AG levels were adjusted from abnormal to normal (8-16mmol/L) upon admission, remaining at a normal level at discharge. This suggests that preoperative EN time may help protect the postoperative cardiac function of patients undergoing heart surgery and prevent cardiac dysfunction.
The clinical significance of the observed metabolic signal also remains limited. Recent studies have found a significant correlation between preoperative malnutrition and postoperative complications, such as delirium, in patients undergoing heart surgery [12]. In elderly patients undergoing non-cardiac surgery, the correlation between preoperative malnutrition and postoperative complications also remains [13]. Rahma et al. noted that while malnutrition is common in elderly patients undergoing non-cardiac surgery, there is no correlation between malnutrition and postoperative delirium [14]. In this study, EN timing was not clearly associated with postoperative delirium, in-hospital mortality, or length of hospital stay. Therefore, it was suggested that the lower AG observed in the preoperative EN group should not be interpreted as direct evidence of improved clinical recovery or cardiac protection. Nevertheless, the positive association between discharge AG and in-hospital mortality is consistent with previous reports [15], suggesting that postoperative AG may have prognostic relevance in cardiac surgery patients. Abbasalizad noted that maintaining proper acid-base balance can reduce the 10-year mortality risk and extend life in CABG patients [16]. These finding supported AG as a metabolic risk marker.
Moreover, the importance of postoperative nutritional support for cardiac surgery patients has not been fully recognized. A prospective study found that patients receiving enteral and parenteral nutrition support after cardiac surgery had a mortality and morbidity rate one order of magnitude higher than those who received oral nutrition [17]. However, Flordelis et al. [18] evaluated the feasibility and safety of early enteral nutrition for hemodynamically failed patients after cardiac surgery. The study found that early enteral nutrition is feasible for these patients without serious complications, with constipation being the most common complication related to enteral nutrition. Currently, there is no consensus on the impact of postoperative enteral nutrition on cardiac surgery patients, and more research is needed to confirm this.
However, several limitations should be acknowledged. In this study, admission type and illness severity measures showed the between-group comparability However, several relevant variables were unavailable or incompletely captured, including detailed indications for EN, exact formula selection, specific procedure categories, and preoperative ICU exposure. These factors may have influenced when EN was started and may partly explain the observed associations. In addition, several subgroups with cardiac surgery had relatively small sample size (such as underweight and normal BMI), which caused wider confidence intervals and indicated that our estimation of the true effect is highly uncertain. Therefore, subgroup analyses were exploratory, and multiple comparisons in relatively small strata may have produced unstable estimates and type I error. In summary, the current study should be considered hypothesis-generating, and prospective studies are needed to determine whether modifying postoperative metabolic trajectories through nutrition-related strategies can improve clinical outcomes.
Conclusions
In this retrospective analysis of cardiac surgery ICU patients from the MIMIC-IV database, preoperative EN was associated with lower postoperative and discharge AG levels compared with postoperative EN. However, no clear association with major clinical outcomes was observed, and residual confounding by indication limits causal interpretation. These findings should be considered hypothesis-generating.
Acknowledgements
Not applicable.
Author contributions
Shan-jiao Chen and Jia-wen Lu contributed to the conception and design. Shan-jiao Chen and Chao-quan Liu contributed to the collection and assembly of data. Jia-wen Lu and Ya-nan Yao analyzed and interpreted the data. All authors wrote and approved the final manuscript.
Funding
This work was supported by the following grants: Danzhou Science and Technology and Industrial Information Development Bureau (No. 2024-77).
Data availability
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
In accordance with the Declaration of Helsinki, the Ethics Committee of Hainan Western Central Hospital deemed that this research is based on open-source data, so the need for ethics approval was waived.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Shan-jiao Chen and Jia-wen Lu contributed equally to this work, and should be regarded as co-first author.
References
- 1.Vervoort D, Meuris B, Meyns B, Verbrugghe P. Global cardiac surgery: Access to cardiac surgical care around the world. J Thorac Cardiovasc Surg. 2020;159(3):987–96. e6. [DOI] [PubMed] [Google Scholar]
- 2.Byiringiro S, Nyirimanzi N, Mucumbitsi J, Kamanzi ER, Swain J. Cardiac Surgery: Increasing Access in Low- and Middle-Income Countries. Curr Cardiol Rep. 2020;22(7):37. [DOI] [PubMed] [Google Scholar]
- 3.Elbayomi M, Weyand M, Seitz T, Harig F. Wearable cardioverter defibrillator after cardiac surgery: Analysis of real-life data from patients at transient risk of sudden cardiac death. Ann Noninvasive Electrocardiol. 2023;28(2):e13048. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Justice L, Buckley JR, Floh A, Horsley M, Alten J, Anand V, et al. Nutrition Considerations in the Pediatric Cardiac Intensive Care Unit Patient. World J Pediatr Congenit Heart Surg. 2018;9(3):333–43. [DOI] [PubMed] [Google Scholar]
- 5.Rzucidlo-Hymczak A, Hymczak H, Kedziora A, Kapelak B, Drwila R, Plicner D. Prognostic role of perioperative acid-base disturbances on the risk of Clostridioides difficile infection in patients undergoing cardiac surgery. PLoS ONE. 2021;16(3):e0248512. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Li J, Tian Y, Wang L, Chen J, Chen X, Huang H, et al. Postoperative anion gap associates with short- and long-term mortality after cardiac surgery: A large-scale cohort study. Front Cardiovasc Med. 2022;9:1024484. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Gao Y, Hong Z, Shen R, Zhang S, You G, Chen J, et al. Association between anion gap and mortality of aortic aneurysm in intensive care unit after open surgery. BMC Cardiovasc Disord. 2021;21(1):458. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Zhang XB, Shu WB, Li AB, Lan GH. The Anion Gap and Mortality in Critically Ill Patients with Hip Fractures. Contrast Media Mol Imaging. 2022;2022:1591507. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Sun X, Lu J, Weng W, Yan Q. Association between anion gap and all-cause mortality of critically ill surgical patients: a retrospective cohort study. BMC Surg. 2023;23(1):226. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Xie K, Zheng C, Wang GM, Diao YF, Luo C, Wang E, et al. Association between delta anion gap and hospital mortality for patients in cardiothoracic surgery recovery unit: a retrospective cohort study. BMC Surg. 2022;22(1):186. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Yang SW, Zhou YJ, Zhao YX, Liu YY, Tian XF, Wang ZJ, et al. The serum anion gap is associated with disease severity and all-cause mortality in coronary artery disease. J Geriatr Cardiol. 2017;14(6):392–400. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Chen Z, Hao Q, Sun R, Zhang Y, Fu H, Liu S, et al. Predictive value of the geriatric nutrition risk index for postoperative delirium in elderly patients undergoing cardiac surgery. CNS Neurosci Ther. 2024;30(2):e14343. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Liu H, Dai M, Guan H, Gao X, Zhou Y, Sun X, et al. Preoperative Prognostic Nutritional Index Value is Related to Postoperative Delirium in Elderly Patients After Noncardiac Surgery: A Retrospective Cohort Study. Risk Manag Healthc Policy. 2021;14:1–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Zhang F, He ST, Zhang Y, Mu DL, Wang DX. Malnutrition is not related with emergence delirium in older patients after noncardiac surgery. BMC Geriatr. 2021;21(1):319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Wang XM, Deng YS, He B, Liu JW, Zhang ZH, Ye ZD, et al. The serum anion gap is associated with the prognosis of coronary artery bypass grafting (CABG): analysis based on the MIMIC-IV database. Eur Rev Med Pharmacol Sci. 2023;27(7):2964–70. [DOI] [PubMed] [Google Scholar]
- 16.Abbasalizad Farhangi M, Vajdi M, Najafi M. Dietary acid load significantly predicts 10-years survival in patients underwent coronary artery bypass grafting (CABG) surgery. PLoS ONE. 2019;14(10):e0223830. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Ong CS, Yesantharao P, Brown PM, Canner JK, Brown TA, Sussman MS, et al. Nutrition Support After Cardiac Surgery: Lessons Learned From a Prospective Study. Semin Thorac Cardiovasc Surg. 2021;33(1):109–15. [DOI] [PubMed] [Google Scholar]
- 18.Flordelis Lasierra JL, Perez-Vela JL, Umezawa Makikado LD, Torres Sanchez E, Colino Gomez L, Maroto Rodriguez B, et al. Early enteral nutrition in patients with hemodynamic failure following cardiac surgery. JPEN J Parenter Enter Nutr. 2015;39(2):154–62. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.