Preoperative fasting is a standard practice to reduce the risk of pulmonary aspiration during anesthesia [1]. Current guidelines recommend fasting for 6–8 hours for solids and 2 hours for clear fluids in pediatric patients [2]. Despite these recommendations, prolonged fasting is frequently observed in clinical practice due to surgical delays, miscommunication, or institutional protocols [3].

Excessive fasting in children may result in hypoglycemia, dehydration, irritability, and hemodynamic instability, as pediatric patients have higher metabolic rates and lower glycogen reserves compared to adults [4,5]. Blood glucose levels are an important indicator of metabolic homeostasis, and alterations can influence heart rate, blood pressure, and mean arterial pressure during anesthesia [6,7].

Previous studies have reported that prolonged fasting can lead to tachycardia, hypotension, and perioperative stress, emphasizing the need for adherence to recommended fasting durations [8,9]. Ensuring optimal fasting duration improves not only metabolic stability but also patient comfort and safety during the perioperative period [10].

The present study aimed to evaluate the effect of preoperative fasting duration on blood glucose levels and hemodynamic parameters in pediatric patients undergoing elective surgery, to inform safer fasting practices in clinical settings.

MATERIALS AND METHODS

Study Design and Setting

This hospital-based, observational case–control study was conducted in the Department of Anesthesiology and Pediatrics at Yadgir Institute of Medical Sciences, Yadgir, from April 1, 2025, to August 31, 2025. The institute serves as a tertiary care referral center catering to both rural and urban populations.

Study Population

A total of 50 pediatric patients, aged 1–12 years, scheduled for elective surgeries under general anesthesia, were enrolled in the study. Patients were divided into two groups based on fasting duration:

• Group A (Standard Fasting Group): 25 patients who fasted according to conventional guidelines (6–8 hours for solids, 2 hours for clear fluids).
• Group B (Prolonged Fasting Group): 25 patients who had longer fasting durations than recommended.

Inclusion Criteria

• Children aged 1–12 years undergoing elective surgery.
• ASA physical status I or II.
• Parents/guardians providing written informed consent.

Exclusion Criteria

• Patients with known endocrine disorders (e.g., diabetes mellitus).
• Patients with gastrointestinal or metabolic disorders affecting glucose homeostasis.
• Emergency surgical cases.
• Children receiving medications affecting blood glucose or hemodynamics.

Study Procedure

• Demographic data, medical history, and fasting duration were recorded for all patients.
• Baseline blood glucose levels were measured using a calibrated glucometer immediately before induction of anesthesia.
• Hemodynamic parameters—heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP)—were recorded at baseline, after induction, and at 5-minute intervals during the first 15 minutes of surgery.
• Anesthesia was induced and maintained according to standard institutional protocols.

Outcome Measures

• Primary Outcome: Effect of preoperative fasting duration on blood glucose levels.
• Secondary Outcome: Changes in hemodynamic parameters during induction and early intraoperative period.

Statistical Analysis

• Data were analyzed using SPSS version 21
• Continuous variables were expressed as mean ± standard deviation (SD), and categorical variables as frequency and percentage.
• Comparisons between groups were made using the independent t-test or Mann–Whitney U test for continuous variables and Chi-square test for categorical variables.
• A p-value <0.05 was considered statistically significant.

RESULTS AND OBSERVATIONS

Table 1: Demographic Characteristics

Table 2: Age Group Distribution

Table 3: Fasting Duration

Figure; 1 Fasting Duration

Table 4: Blood Glucose Levels

Table 5: Heart Rate (beats/min) Trend

Table 6: Systolic and Diastolic Blood Pressure (mmHg)

Table 7: Mean Arterial Pressure (MAP, mmHg)

Figure 2 Mean Arterial Pressure (MAP, mmHg)

Table 8: Incidence of Hemodynamic Instability

Table 9: Comparative Summary of Fasting Duration, Blood Glucose, and Hemodynamic Outcomes

DISCUSSION

The present study evaluated the effect of preoperative fasting duration on blood glucose levels and hemodynamic parameters in pediatric patients undergoing elective surgery. Our results demonstrate that prolonged fasting is associated with significantly lower blood glucose levels and notable hemodynamic alterations compared to standard fasting durations.

Blood Glucose Levels

In this study, the mean preoperative blood glucose level in the prolonged fasting group was 83.6 ± 9.8 mg/dL, significantly lower than 95.2 ± 10.5 mg/dL observed in the standard fasting group. This finding is consistent with the observations of Brown et al. (2018), who reported that fasting beyond recommended durations in children led to a significant reduction in glucose levels, predisposing them to hypoglycemia and metabolic stress [1]. Similarly, Williams et al. (2016) emphasized that pediatric patients have higher basal metabolic rates and limited glycogen reserves, making them more susceptible to fasting-induced hypoglycemia [2].

However, the observed blood glucose levels, although statistically lower, remained within clinically acceptable ranges in most patients, similar to findings reported by Green et al. (2019), who noted that short-term deviations from fasting guidelines rarely resulted in critical hypoglycemia in otherwise healthy pediatric populations [3]. This suggests that while prolonged fasting does reduce glucose, the effect may be partially mitigated by preoperative hydration and intraoperative glucose monitoring.

Hemodynamic Parameters

Our study demonstrated that prolonged fasting was associated with higher heart rates and lower mean arterial pressures during induction and early intraoperative period. Group B (prolonged fasting) showed peak HR values of 114 ± 16 bpm, compared to 105 ± 15 bpm in Group A, and MAP reductions >15% from baseline were more frequent (9/25 vs. 2/25). These results align with Patel et al. (2020), who observed tachycardia and hypotension in children subjected to extended fasting, attributing this to relative hypovolemia, decreased plasma glucose, and compensatory sympathetic activation [4].

In contrast, Wilson et al. (2019) reported that minor prolongation of fasting (1–2 hours beyond guidelines) did not significantly affect hemodynamic stability, indicating that the degree of fasting deviation plays a critical role in physiologic stress [5]. The discrepancies between studies may be related to variations in patient age, baseline nutritional status, and anesthetic protocols.

Systolic and diastolic blood pressure trends in our study demonstrated slightly lower values in the prolonged fasting group, particularly after induction and at 5–10 minutes intraoperatively. Similar findings were reported by Kumar et al. (2021), who suggested that fasting-induced hypovolemia and decreased intravascular volume contribute to transient hypotension during anesthetic induction [6].

Comparison with Previous Literature

Several studies have highlighted the clinical consequences of prolonged fasting in children. Brown et al. (2018) reported a mean reduction of 12–15 mg/dL in preoperative glucose levels with fasting beyond recommended durations, which is comparable to the 11.6 mg/dL difference observed in our study [1]. Patel et al. (2020) and Lee et al. (2018) demonstrated higher HR and lower MAP in prolonged fasting groups, consistent with our results [4,7].

Conversely, studies by Smith et al. (2020) and Taylor et al. (2021) reported that adherence to 2-hour fluid fasting and 6-hour solid fasting guidelines minimized hemodynamic instability and maintained euglycemia, reinforcing the importance of guideline compliance [8,9].

The comparison indicates that while mild prolongation of fasting may not always result in clinically critical derangements, significant deviations increase perioperative metabolic stress and hemodynamic fluctuations, potentially affecting anesthesia safety and patient comfort.

Physiological Mechanisms

The observed decrease in blood glucose in prolonged fasting can be explained by glycogen depletion and increased gluconeogenesis in children with limited hepatic glycogen stores. Reduced intravascular volume due to fasting leads to sympathetic nervous system activation, resulting in tachycardia as a compensatory mechanism, while hypotension may occur due to relative hypovolemia and vasodilation under anesthesia [2,4,6].

Maintaining adequate hydration and minimizing unnecessary fasting can therefore stabilize blood glucose and hemodynamics, reducing perioperative stress and improving outcomes in pediatric patients.

Clinical Implications

Our findings have important clinical implications:

1. Adherence to evidence-based fasting guidelines is crucial to prevent hypoglycemia and hemodynamic instability.
2. Allowing clear fluids up to 2 hours preoperatively is safe and improves patient comfort.
3. Monitoring blood glucose and hemodynamic parameters during induction is recommended, particularly in children subjected to prolonged fasting.
4. Hospital protocols should emphasize scheduling, caregiver education, and real-time verification of fasting duration to prevent unnecessary prolongation.

CONCLUSION

The present study demonstrates that prolonged preoperative fasting in pediatric patients is associated with significantly lower blood glucose levels and notable hemodynamic alterations, including higher heart rates and a greater incidence of mean arterial pressure reductions, compared to standard fasting durations. Although most children remained within clinically acceptable glucose ranges, prolonged fasting increases perioperative metabolic stress and hemodynamic instability, which may compromise patient safety and comfort.

Adherence to evidence-based fasting guidelines—6–8 hours for solids and 2 hours for clear fluids—along with careful monitoring of blood glucose and hemodynamic parameters, is essential to minimize perioperative risks. Optimizing fasting practices, including allowing clear fluids up to 2 hours before surgery, can enhance metabolic stability, maintain hemodynamic equilibrium, and improve overall perioperative outcomes in pediatric patients.

REFERENCES

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2. Williams R, et al. Pediatric metabolism and preoperative fasting. Paediatr Drugs. 2016;18:423–432.
3. Green T, et al. Blood glucose monitoring in children undergoing anesthesia. Paediatr Anaesth. 2019;29:335–342.
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