Abstract

Objective: To review the main risk factors for postoperative complications in neonates and provide references for optimizing perioperative management.
Methods: Literature published between 2000 and 2024 in databases such as PubMed was retrieved. Patient-, surgical-, and anesthesia-related risk factors for postoperative complications in neonates were summarized and analyzed.
Results: The occurrence of postoperative complications in neonates is the result of multiple factors. Patient factors, such as prematurity, low birth weight, and severe comorbidities; surgical factors, such as emergency surgery and operation duration; and anesthesia- and perioperative management-related factors, such as preoperative status and intraoperative hemodynamic fluctuations, are all key elements affecting prognosis.
Conclusion: Identifying and evaluating high-risk factors and performing preoperative optimization and refined intraoperative management through multidisciplinary collaboration are important strategies to reduce the incidence of postoperative complications in neonates and improve their surgical outcomes.

NewbornPostoperative ComplicationsRisk FactorsPerioperative Management

Introduction

The neonatal period (within 28 days after birth) is the stage of life with the most dramatic physiological changes and the greatest vulnerability. Due to the incomplete development of the structure and function of various systems and organs, as well as poor self-regulation and compensatory capacity, neonates are highly susceptible to major organ injury, infections, and even death during the perioperative period, making them a recognized high-risk population [1,2]. With advancements in neonatal intensive care units (NICUs) and surgical techniques, the survival rate of neonates undergoing surgery has significantly improved; however, there remains a substantial disparity in mortality rates worldwide [3].

Previous studies have mostly focused on the surgical outcomes of individual conditions, such as esophageal atresia or congenital diaphragmatic hernia, lacking a comprehensive review of risk factors for postoperative complications in neonates. Although there have been studies exploring neonatal surgical risks, the definitions and descriptions of postoperative complications vary, making data integration and comparison difficult. Moreover, there is a lack of systematic analysis from the anesthesiologist's perspective regarding the interaction among patient factors, surgical factors, and anesthesia-related factors. This paper aims to summarize the main risk factors for postoperative complications in neonates by reviewing the existing literature, providing strategies for perioperative risk assessment and refined management, and offering a theoretical basis for reducing the incidence of complications and improving long-term outcomes in affected infants.

Literature Search Strategy

This study used keywords such as "Newborns/Neonates," "Postoperative Complications," and "Risk Factors" to search the PubMed database for English-language literature published between January 2000 and December 2024. The inclusion criteria were: (1) the study subjects were newborns; (2) the interventions involved surgical treatment (excluding cardiac surgery); and (3) the outcome indicators were related to postoperative complications or mortality. The exclusion criteria were: (1) populations other than newborns; (2) no surgical intervention performed; (3) cardiac surgery; and (4) studies focusing solely on extremely rare diseases or the technical details of a single surgical procedure. Ultimately, 10 representative studies were selected for review [4-13].

Analysis of Risk Factors for Postoperative Complications in Newborns

A comprehensive analysis of the existing literature indicates that the risk factors affecting postoperative complications in newborns can be categorized into three main types: patient factors, surgical factors, and anesthesia- and perioperative management-related factors (Table-1).

TABLE 1

Table-1: Summary of Risk Factors for Postoperative Complications in Neonates

First Author and Year	Study Design	Sample Size	Primary Outcome Measures	Independent Risk Factors	Remarks
Lillehei CW, 2012[4]	Retrospective analysis	15,278	mortality	Premature birth, severe respiratory disease NEC、Neonatal sepsis, congenital heart disease	Large sample multicenter study
Catré D, 2013[5]	Retrospective analysis	437	complications	Reoperation, congenital diaphragmatic hernia, gestational age <32 weeks, abdominal surgery
Catre D, 2013[6]	Retrospective analysis	437	mortality	ASA grade ≥ III, nec/ gastrointestinal perforation
Stey AM, 2015[7]	Retrospective analysis	2907	adverse events	Infection cases, preoperative dialysis, abdominal / hepatobiliary diseases, use of inotropic drugs	For large abdominal / thoracic surgery
Michelet D, 2017[8]	Retrospective analysis	168	complications	Corrected for gestational age <40 weeks, cardiac malformations, HMD or NEC, and preoperative ICU status
Puri A, 2019[9]	Retrospective analysis	150	mortality	Operation time >120 minutes, prolonged ventilation, high-dose vasopressors, reoperation	Research in resource limited environment
Song L, 2019[10]	Retrospective analysis	142	mortality	NEC、Be value before intubation and immediately after laparotomy ≤ -10 mmol/l	Single center study
Nasr VG, 2019[11]	Retrospective analysis	3,67,065	mortality	Weight <5kg, ASA grade≥ III, preoperative sepsis, inotropic drug support	Research on super large scale database
Ammar S, 2020[12]	Retrospective analysis	182	mortality	Low birth weight, preoperative intubation, operation time >2h
Kammoun M, 2024[13]	Prospective observation	67	mortality	Reoperation, operation time ≥ 120 minutes, preoperative mechanical ventilation	The latest prospective study

Patient-Related Factors: Uncontrollable Baseline Risks

The baseline condition of the patient is the underlying determinant of postoperative outcomes, with prematurity, low birth weight, and comorbidities being the core factors affecting prognosis. Multiple studies have consistently shown that the incidence of adverse events after surgery is significantly higher in preterm infants than in full-term infants [4,5,8]. The pathophysiological basis lies in the marked immaturity of various organ systems.

Cardiovascular System

Immature myocardial cells exhibit a disorganized structure, with significantly reduced ventricular compliance, poor tolerance to changes in volume load, and a high risk of heart failure [14]. Additionally, autonomic nervous regulation is not well developed. Under anesthesia, sympathetic nerve activity is suppressed, further reducing cardiovascular compensatory capacity and often necessitating reliance on vasoactive drugs to maintain circulatory stability [15,16].

Respiratory System

Preterm infants have insufficient alveolar surfactant production, low functional residual capacity (FRC), and underdeveloped respiratory centers, making them highly susceptible to postoperative apnea, atelectasis, and hypoxemia [17,18]. Moreover, their airways are narrow, with poor expectoration ability, leading to a high risk of reintubation [19].

Comorbidities

Congenital heart disease (CHD) is another significant risk factor [4,8]. Even when undergoing non-cardiac surgery, surgical stress, hypoxia, and hypercapnia can increase pulmonary vascular resistance, causing previously functionally closed ducts or the foramen ovale to reopen, resulting in right-to-left shunting, exacerbating hypoxia, and even triggering pulmonary hypertensive crises [20,21].

Necrotizing enterocolitis (NEC), a common and severe disease in preterm infants, not only has a high intrinsic mortality rate but can also trigger systemic inflammatory response syndrome (SIRS), leading to intestinal mucosal necrosis, perforation, and a cytokine storm, which can cause sepsis, septic shock, and multiple organ dysfunction, greatly increasing perioperative risk [4,6,8,10,22]. Although peritoneal drainage and laparotomy are effective treatments, postoperative complications such as intestinal strictures, short bowel syndrome, and liver and kidney dysfunction are frequent [23,24], significantly prolonging the duration of invasive ventilation and hospital stay, increasing medical costs, and reducing long-term quality of life.

Surgery-Related Factors: Controllable Intervention Window

Compared with patient-related factors, surgery-related factors provide an important window for clinical intervention.

Emergency Surgery

Multiple studies have confirmed that, compared with elective surgery, emergency surgery is significantly associated with higher morbidity and mortality [25,26]. This is not solely determined by the disease itself but is closely related to insufficient time for preoperative optimization in the emergency setting [25]. Neonates undergoing emergency surgery often have severe infections, shock, acid-base disturbances, and electrolyte imbalances, making it extremely difficult for anesthesiologists to stabilize their physiological status within a very short time. Therefore, establishing an efficient neonatal transport system and performing rapid and effective preoperative resuscitation and stabilization are key to improving the prognosis of emergency surgery.

Duration and Type of Surgery

Prolonged surgery, generally defined as >2 hours, is recognized as a risk factor in multiple studies [9,10,12]. Longer surgeries mean longer anesthesia exposure, larger fluid shifts, a higher risk of hypothermia, and more intense stress responses. Although the impact of the type of surgery, e.g., abdominal surgery vs. thoracic surgery, remains controversial, it is generally believed that the complexity of the surgery and whether it involves intestinal necrosis or severe infection have a greater impact on prognosis than the surgical site alone [5,13].

Anesthesia and Perioperative Management Factors: The Core Role of the Anesthesiologist

Anesthesia management extends throughout the entire perioperative period and is a critical component in improving neonatal outcomes.

Preoperative Status Optimization

Preoperative Assessment and Optimization: An American Society of Anesthesiologists (ASA) classification of ≥III is a strong predictor of postoperative adverse events in neonates [6,11], as it comprehensively reflects the presence of severe systemic disease preoperatively. Being in the ICU preoperatively, requiring mechanical ventilation, or needing positive inotropic support all indicate that the patient’s physiological reserve is nearing exhaustion, which predicts a higher risk [8,11-13].

Therefore, optimizing hemoglobin levels, improving nutrition, and stabilizing circulatory and respiratory function as much as possible before surgery are the cornerstones of risk reduction.

Intraoperative Precision Management

Hemodynamic Management: The neonatal cardiovascular system is fragile and highly sensitive to changes in volume and vascular tone [14]. Intraoperative hypotension or hypertension, as well as tachycardia or bradycardia, may cause irreversible damage to the perfusion of vital organs. The use of vasoactive drugs during surgery is a necessary means of maintaining circulation, but their use also reflects the severity of the condition, and improper use may worsen microcirculatory disorders [7,9,11].

Fluid and Metabolic Management: Due to the relatively large body surface area and low apparent water loss in neonates, coupled with immature renal function, they have poor tolerance to fluid overload or deficit. Improper intraoperative fluid management can result in pulmonary edema or acute kidney injury. Although goal-directed fluid therapy (GDFT) is widely used in adults, the optimal strategy for neonates still needs to be explored [8]. Additionally, severe metabolic acidosis, e.g., immediate post-laparotomy base excess ≤ -10 mmol/L, can suppress myocardial contractility and reduce vascular responsiveness to catecholamines, which is closely associated with increased postoperative mortality [10].

Temperature Protection: Neonates have relatively large body surface areas and immature thermoregulatory centers, making them prone to intraoperative hypothermia. Hypothermia can lead to coagulation dysfunction, slowed drug metabolism, an increased risk of postoperative infection, and a series of other complications.

Choice of Anesthesia Method: Although the potential neurotoxicity of general anesthetics on the developing nervous system has raised significant concern, current evidence indicates that a single, short-duration general anesthesia has no significant long-term impact on neurodevelopment [27]. In contrast, regional blocks, such as neuraxial or nerve blocks, as part of multimodal analgesia, can help reduce the dose of general anesthetics, provide postoperative pain relief, and facilitate early extubation, which may be a beneficial adjunct for critically ill neonates [28].

Discussion and Prospects

The occurrence of postoperative complications in neonates is not the result of a single factor but rather a "risk cascade" resulting from the interaction among patient baseline risk, surgical trauma and stress, and the quality of anesthetic management. For an extremely low birth weight preterm infant (patient factor) requiring emergency laparotomy due to NEC (comorbidity) and experiencing intraoperative refractory acidosis and hypotension (anesthetic factors), the risk increases exponentially.

A notable feature of current studies is that reported risk factors differ across studies, and the definitions of postoperative complications have not yet been standardized, making high-quality meta-analyses difficult. Moreover, most studies are retrospective analyses and have inherent biases. In the future, it is necessary to establish a multicenter neonatal surgical anesthesia database in China, unify outcome indicators, and develop risk prediction models suitable for the Chinese population to achieve more precise risk stratification.

More importantly, improving neonatal surgical outcomes cannot rely solely on the efforts of a single discipline. Multidisciplinary collaboration (MDT) among neonatal surgery, neonatology, anesthesiology, and critical care is essential. From prenatal diagnosis and delivery planning to preoperative stabilization, intraoperative anesthesia, and postoperative intensive care, establishing a seamless closed-loop management system is the fundamental approach to reducing complications and improving long-term outcomes for neonates.

Conflict of Interest

The author has read and approved the final version of the manuscript. The author declares no conflicts of interest.

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