Bali Journal of Anesthesiology

: 2021  |  Volume : 5  |  Issue : 1  |  Page : 1--5

Effect of supplemental caudal analgesia on intraoperative blood glucose levels in pediatric patients undergoing urological surgery under general anesthesia: An observational study

Apurva Sadhoo, Sunil Rajan, Sowmya Jain, Kaushik Barua, Lakshmi Kumar 
 Department of Anaesthesia, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India

Correspondence Address:
Dr. Lakshmi Kumar
Department of Anaesthesia, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala


Background: The need for intra-operative dextrose supplementation in pediatrics remains a debate. Surgical stress responses lead to hyperglycemia, while regional anesthesia obtunds the stress response and thereby, hyperglycemia. We aimed to compare the effects of supplemental caudal analgesia on intraoperative blood glucose in children undergoing urological surgery under general anesthesia (GA). Intraoperative hemodynamics and opioid consumption were also compared. Patients and Methods: This was a cross-sectional, observational study conducted in children aged 5 months–6 years undergoing urological surgery, categorized as Group R (GA with caudal analgesia) or Group G (GA only). Blood sugars were measured until 2 h following intubation. Statistical analysis was performed using the Student's t-test and Chi-square tests. Results: Age in Group R was lesser than Group G (P = 0.044), but weights were comparable. Random blood sugar (RBS) at 60 min (P = 0.008) and 90 min (P = 0.007) were significantly lower in Group R. The difference in RBS from the baseline was significantly higher in Group G at all time points. Heart rate (HR) and mean arterial pressure (MAP) were comparable except at HR 60 (P = 0.046) and MAP 60 (P = 0.014) with significantly higher values in Group G. Group R had significantly lower intraoperative fentanyl consumption with less frequent need for additional bolus. Conclusions: Supplemental caudal analgesia blunts intraoperative increases in blood glucose levels and hemodynamics with a reduced analgesic requirement, compared to GA alone in children undergoing urological surgery.

How to cite this article:
Sadhoo A, Rajan S, Jain S, Barua K, Kumar L. Effect of supplemental caudal analgesia on intraoperative blood glucose levels in pediatric patients undergoing urological surgery under general anesthesia: An observational study.Bali J Anaesthesiol 2021;5:1-5

How to cite this URL:
Sadhoo A, Rajan S, Jain S, Barua K, Kumar L. Effect of supplemental caudal analgesia on intraoperative blood glucose levels in pediatric patients undergoing urological surgery under general anesthesia: An observational study. Bali J Anaesthesiol [serial online] 2021 [cited 2022 Dec 5 ];5:1-5
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Although the fasting guidelines include the administration of clear fluids until 2 h before the surgery, its implementation is challenging due to the limitations in patient awareness and compliance.[1],[2] However, guidelines are inconclusive on the requirement of glucose among patients receiving GA with supplemental regional analgesia. It is a standard practice to include dextrose supplementation to intravenous (IV) fluids in infants and children undergoing prolonged surgery. Although asymptomatic hypoglycemia has been reported in children presenting to the outpatient department,[3] intraoperative hyperglycemia is common, secondary to increased release of catecholamines during the surgery.

Surgery predisposes to an increase in blood glucose as a result of the release of cortisol, causing hepatic glycogenolysis along with reduced peripheral utilization of glucose due to secondary insulin resistance.[4],[5] The use of regional blocks during general anesthesia (GA) may optimize blood glucose levels to a more physiological state by the suppression of endogenous glucose production.[5] At our institute that caters to a large number of pediatric urological surgical patients, intraoperative supplementation of dextrose is practiced in all surgeries lasting for more than 1 h in duration.

The primary objective of the present study was to compare the changes in blood glucose levels in children undergoing urological surgical procedures under GA with and without supplemental caudal analgesia. Secondary outcome measures were assessment of hemodynamic responses and opioid requirements during the surgery in both groups.

 Patients and Methods

This prospective, observational study was conducted from August 2019 to February 2020. Children aged 5 months to 6 years, belonging to the American Society of Anesthesiologists physical status 1 and 2, undergoing urological procedures lasting more than 1 h were included as per the surgical schedule [Figure 1]. As per the anesthesia and surgical practices, children undergoing hypospadiasis repair were allotted to one group, Group G, who received GA only. All other surgical procedures were allotted to Group R (GA with supplemental caudal) at the discretion of the covering anesthesiologist. The anesthesiologists involved were not blinded to group allotment of patients as this was an observational study, and the measurement of blood sugar was an objective assessment.{Figure 1}

After obtaining the consent from the Institutional Ethics Committee (IEC-AIMS-2019-ANES-003 dated January 21, 2019) and the parents, children were recruited into the study. Children with baseline blood sugar <70 mg/dL, history of endocrine disorder, or on steroid supplementation were excluded. This study was registered with Clinical Trial Registry India (CTRI/2019/07/020257, dated July 18, 2019). The decision for caudal analgesia was as per prevailing institutional practices and the discretion of the covering anesthesiologist for the type of surgery. Sixty-four children meeting the criteria were included for the study, of which 15 were excluded on account of hypoglycemia with fasting sugar <70 mg/dL at the point of allotment.

The children were fasted for 6 h for solids and encouraged to have clear fluids until 2 h before surgery.[1],[6] Infants were allowed formula feeds or solids 6 h prior, breast milk 4 h, and clear fluids that included water, apple juice, or tender coconut water until 2 h before the surgery. All children received an IV infusion of Isolyte-P (B-Braun) at the maintenance dose recommended by Holliday and Segar[7] from the time of fasting until the start of surgery. As all children had indwelling IV access, ketamine 1 mg/kg body weight with glycopyrrolate 5 μg/kg body weight was administered intravenously to allow a smooth separation from the parent.

In the theatre, after placement of preinduction monitors that included the pulse oximeter and electrocardiogram, anesthesia was induced by standard protocols. Preexisting IV lines were rechecked for patency, and if excessive resistance was encountered or the child demonstrated pain on injection, new ones replaced those lines, and a free flow of IV fluid was confirmed. Fentanyl 2 μg/kg and propofol 1–2 mg/kg were administered intravenously and airway secured after the administration of atracurium 0.5 mg/kg.

All children were intubated with an endotracheal tube appropriate for age, and anesthesia was maintained with an air oxygen mixture (1:1) at 1.0 L fresh gas flow.[8],[9] End-tidal sevoflurane at 0.7–1.0 minimum alveolar concentration was ensured on an Avance GE CS2 workstation equipped with a gas analyzer and inspired oxygen monitor. The patients designated in the regional group, Group R, received a single shot of caudal analgesia with ropivacaine (0.2%) at 1 ml/kg (2 mg/kg) following intubation. Children in whom technical difficulties were encountered during the caudal administration were excluded from the study.

Ringer's lactate (RL) with 1% dextrose solution was prepared by replacing 20 mL RL with 20 mL of 25% dextrose. This was administered as per the Holliday-Segar formula. Any additional fluid replacement was replaced with plain RL without the addition of dextrose. Blood sugar estimations were done using glucose measurement strips on a glucometer (FreeStyle Optium H System, Copyright© 2015 Abbott Laboratories. Abbott Park, Illinois, USA). The first Random blood sugar (RBS) reading was taken soon after the patient was induced and before initiating dextrose containing IV fluid. Subsequent readings were taken at 30 min intervals to a maximum of 2 h of surgery.

If the blood sugar value was <70 mg/dL at any point in these children, they were treated with 1 mL/kg body weight of 25% dextrose intravenously diluted with IV fluid and were excluded from further analysis.[2] If the blood sugars were higher than 200 mg/dL, then the IV maintenance fluid was changed to plain RL. Hyperglycemia was defined as blood sugars >150 mg/dL and hypoglycemia as blood sugars <70 mg/dL and any incidence of hypoglycemia or hyperglycemia were documented.[3],[10]

The sample size was determined from a pilot study conducted in 20 patients as there were no comparable studies at the time of initiation of the study. The Chi-square test compared the age and gender. The duration of surgery, blood glucose, and hemodynamics were assessed by the Student's t-test using the SPSS software version 20.0 for Windows (IBM Corporation Armonk, NY, USA).


Data of 49 children were analyzed [Figure 1]. Fourteen children were excluded after induction as the baseline blood glucose was <70 mg/dL. The demographic profile of the participants is presented in [Table 1]. The baseline RBS in both groups was similar (88.3 ± 13.2 vs. 85.3 ± 10.6 mg/dL). RBS was significantly higher in Group G at 60 and 90 min [Table 2]. When the mean difference of RBS from the baseline in each group was compared, we found that participants in Group G had a significantly higher increase compared to Group R [Table 2]. There was no incidence of hypoglycemia or hyperglycemia in both groups perioperatively.{Table 1}{Table 2}

The heart rate (HR) and mean arterial pressure (MAP) at 60 min were significantly higher in Group G (P < 0.05) but were comparable at all other time points [Table 3], [Figure 2] and [Figure 3]. Mean fentanyl consumption was significantly higher in Group G compared to Group R (32.5 ± 13.7 vs. 18.6 ± 6.3 μg, P < 0.001). The number of times of additional fentanyl bolus required intraoperatively was also significantly higher in Group G compared to Group R (P < 0.001).{Table 3}{Figure 2}{Figure 3}


We found that the supplementation of caudal analgesia reduced the surgical stress responses and maintained the blood sugars close to the reference range in comparison to the group without caudal analgesia. Although an elevation of blood sugars was seen toward the end of the surgery, the increase was more in the group that received GA only. We also observed attenuation of the hemodynamic responses, which was maximally seen at 60 min following supplemental caudal block.

Even with advice for clear fluids, parents' noncompliance due to fear of cancellation of surgeries led to longer than desired periods of fasting. This was similar to the study by Singla et al.[1] who found that 86.4% of children presenting to the outpatient department had fasted for longer durations and that only 8.5% were compliant to the suggested duration of fasting. We found that 15 children had fasting hypoglycemia that may have been missed without routine monitoring. Although an order for Isolyte-P containing 5% dextrose was made in the surgical ward, positional flow through small veins may have affected the replacement. RL solution does not affect blood glucose levels in nondiabetics and was found to have comparable blood glucose to an acetated solution in healthy liver donors.[11]

The European Society for Pediatric Anesthesiology recommends that the osmolarity of pediatric intraoperative fluid should be as physiological as possible and the concentration of glucose to be kept at 1%–2.5% instead of 5% to avoid hypoglycemia, lipolysis, or hyperglycemia during the perioperative period.[12] In a more recent review, Bhardwaj[13] reported that perioperative hypoglycemia is common with fasting periods of 8–19 h suggests that a routine replacement of dextrose in healthy pediatric patients may not be needed. However, the same author states that the Association of Pediatric Anesthetists of Great Britain and Ireland recommend that supplementation of 1%–2.5% dextrose in children undergoing surgery maintains blood glucose levels and prevents electrolyte imbalances. This suggests that practices are perhaps territorial and may be tailored to the optimal practice at that center. Our documentation of undetected hypoglycemia led us to believe that at our center, the use of dextrose containing solutions was safer, as consequences of hypoglycemia can be catastrophic and permanent.[1]

There is a paucity of recent literature on the impact of regional anesthesia on stress responses in pediatric surgery. As this was an observational study, we recruited patients receiving caudal analgesia per the standard anesthesia practices at our institution. Laparoscopic procedures were included in both groups for the evaluation of the stress responses. Pneumoperitoneum at pressures below 12 mmHg did not affect the oxidative stress responses measured by thiol/disulfide homeostasis.[14] Caudal analgesia at 1.3 mL of 0.15% ropivacaine was shown to decrease pain responses in pediatric laparoscopic urological surgery.[15]

The most commonly used technique of regional anesthesia performed in children for surgical interventions below the level of the umbilicus is a caudal block.[16],[17] In a randomized control trial in 60 children, it was shown that the use of caudal analgesia decreased blood glucose, serum cortisol, and pain scores after the surgery and provided hemodynamic stability intraoperatively. This reflects an attenuation of the surgical stress response.[18] These findings are similar to another study in adults that have documented decreased cortisol levels at 30 min of the start of surgery and the end of surgery in patients receiving general versus epidural anesthesia.[19]

Our results were similar and suggested that the addition of a caudal block reduced the stress response as suggested by blood glucose levels and hemodynamic responses in comparison to GA alone. Surprisingly, although one would expect more stable cardiovascular status with a caudal block, the use of a trans-esophageal Doppler in children undergoing urological surgery failed to show any differences between a caudal block and balanced anesthesia with remifentanil on corrected flow time or HR, systolic blood pressure, or MAP.[20] Another study demonstrated no significant changes in HR or MAP but a decrease in descending aortic flow and a decrease in systemic vascular resistance after the administration of caudal anesthesia.[21] Similar observations were made in our study with comparable hemodynamic parameters in both groups except at 60 min after the block. Although the MAP remained in the lower side in Group R, this was not significant clinically or statistically.

Our study has also shown that the consumption of fentanyl was significantly lower in patients receiving caudal block. The explanation for this could be the highly effective analgesia provided by caudal block.[22] The mere observation of the hemodynamic responses observed in our study could be deceiving unless the concurrent opioid requirements are interpreted alongside. Both the total dose of opioids and the number of times an intervention had to be initiated for pain were significantly higher in Group G. This would mean that the hemodynamics could have been higher in Group G and were effectively curtailed by additional opioids. Our results demonstrated that a combination of caudal block with GA led to lowered blood glucose levels, prevented hyperglycemia, and reduced the stress responses associated with surgery.

We acknowledge the limitations of our study. As part of a research project over a year, we were compelled to include all eligible cases which were scheduled for urological surgeries. This eventually resulted in a disparity in age and types of surgeries the children underwent in the study groups. As the anesthesiologists were not blinded to the groups, the bias in treatment with opioids in Group G may have occurred. Measurement of serum cortisol levels might have quantified the stress responses more effectively. A prospective randomized study with larger numbers and similar surgical cases may bring the impact of regional analgesia on blood glucose with greater clarity.


Supplementation of caudal analgesia with GA blunts intraoperative increases in blood glucose levels and hemodynamic parameters with a reduced analgesic requirement, compared to GA alone in children undergoing urological surgery.

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Conflicts of interest

There are no conflicts of interest.


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