In this meta-analysis, we investigated the impact of preoperative nutritional status on immediate postoperative outcomes in children undergoing CHD surgery. The results showed that malnourished children had significantly longer LOS in the hospital and the ICU, a higher risk of prolonged mechanical ventilation, and a greater mortality risk score. However, there was no significant difference in mortality and postoperative infection rates between malnourished and well-nourished children.
Several factors act as determinants of hospitalization time in postoperative CHD patients including the complexity of CHD and existing comorbidities, the type of procedure done, postoperative complications, delay of sternal closure, etc.41,52–55. Malnutrition has been long known to be strongly associated with poor wound healing and impaired immunity, which ultimately contribute to postoperative complications and a longer ICU and hospital stay56,57. Previous studies have postulated that decreased immunity caused by malnutrition impedes effective physiological stress response produced during surgery22. One study determined the impact of malnutrition on organ dysfunction following surgery, concluding that malnutrition is significantly associated with higher rates of organ dysfunction, which ultimately increases the ICU stay45. Additionally, our review revealed that malnourished children were associated with a higher mortality risk score (RACHS-1 or STAT score), which aligns with findings from a large-scale cohort conducted in China where an RACHS-1 score of > 3 was strongly associated with malnutrition58. This demonstrates two things: the extent of malnutrition can be influenced by the severity of the heart defect, and malnourished CHD patients have a higher risk of developing poor outcomes. It is also important to note that these risk scores do not take malnutrition into account and it might be beneficial to conduct further studies to add this component, which can make these scores more robust and accurate.
A randomized controlled trial conducted in Egypt on 40 malnourished pediatric CHD patients demonstrated that a short-term nutritional rehabilitation program was associated with shorter ICU and hospital LOS and mechanical ventilation duration59. Similar to our study, increased mechanical ventilation time has been reported by multiple studies in malnourished postoperative CHD patients, which can potentially contribute to an increased mortality rate52,60–62. However, some studies show no significant association between malnutrition and ventilation time63,64. Malnutrition can directly cause loss of diaphragmatic muscle mass and reduction in lung capacity and function, leading to prolonged requirement of mechanical ventilation. Furthermore, a reduced immune response and development of pneumonia might also explain prolonged ventilator requirements in these patients65,66.
Contrary to other studies in the review, one study from India concluded that poor nutritional status was not adversely associated with mortality41. This is most likely because most of the malnourished children in this study belonged to risk category 1 (RACHS-1), hence their risk of mortality and rate of postoperative complications were lower.
Studies included in our review were conducted in a mix of high-, upper-middle- and lower-middle-income countries. Wide disparities exist in healthcare infrastructure and delivery between HICs and MICs owing to resource and expertise limitations in MICs. This includes a lack of trained personnel and ineffective government policies, along with a dearth of general education and caregiver awareness, and a higher burden of malnutrition. Resource limitations like the unavailability of fully functional cardiac care centers are a huge factor contributing to poor surgical outcomes7,41,67,68. However, our study revealed that the effect of pre-operative nutrition on post-operative outcomes was similar in both settings. This could be a result of heterogeneity in the study populations within both high-income and middle-income countries, leading to variations in outcomes. Moreover, subgroup analyses have limitations, including reduced statistical power (especially with the small number of studies in our review) and potential for confounding factors. Despite conducting subgroup analysis based on income level, there may still be unaccounted variations within the groups that could influence the results.
Limited studies have explored the impact of caregiver practices on the nutritional growth and development of patients with CHD17,69,70. Differences in literacy level and socioeconomic backgrounds can affect feeding practices, which in turn plays a role in malnutrition and hence post-surgical outcomes71. This opens a gateway to the importance of presurgical systematic nutritional assessment, parental counseling, and raising awareness amongst caregivers regarding optimizing nutrition before surgery. The findings of this study have several implications for clinical practice. Firstly, clinicians should be aware that malnutrition is an important risk factor for poor postoperative outcomes in children undergoing surgery for CHD. Secondly, clinicians should identify and address malnutrition in children with CHD prior to surgery. Nutritional interventions such as enteral or parenteral nutrition can help to improve the nutritional status of malnourished children and reduce the risk of postoperative complications. Thirdly, clinicians should continue to monitor the nutritional status of children with CHD after surgery and provide appropriate nutritional support as needed.
This review paves the way for different potential routes to future research. Further research is needed to identify the most effective nutritional interventions to improve the outcomes of children with CHD and to develop and evaluate new methods to identify and assess malnutrition in children with CHD. Moreover, mechanisms need to be identified through which malnutrition contributes to poor postoperative outcomes in children with CHD so we can develop and evaluate new strategies to prevent malnutrition in children with CHD.
Strengths and Limitations
This is the first meta-analysis showing the effect of nutritional status on the immediate postoperative outcomes after CHD surgery. Our study combines data from various global settings, increasing the overall generalizability of the results, and making it applicable to a broader population of children with CHD. The findings can have direct implications for clinicians and healthcare providers, helping them make informed decisions about preoperative nutrition strategies to optimize postoperative outcomes.
The findings of this study are limited by the small number of studies included in the meta-analysis. Although clinical trials were eligible to be included as a part of our review, no trial was found to contain the comparator group (well-nourished patients) and hence, were all excluded during the screening process. Consequently, this review only contains observational studies. Additionally, the studies were heterogeneous in terms of the type of CHD, the definition of malnutrition, and the methods used to assess postoperative outcomes. The differences between acute and chronic malnutrition, and the long-term impact on the quality of life post-surgery were not explored in this study. Non-English articles were not included in the study due to limited resources, which might reduce the generalizability of results. Further large-scale studies are needed to confirm the findings of this study and to identify the most effective nutritional interventions to improve the outcomes of children with CHD.