AMPJ Journal

Keywords: Fluid therapy; Glucose 1%; Intraoperative management; Paediatric anaesthesia

Introduction

Paediatrics comprise a significant percentage of the population. Many will require anaesthesia to treat various surgical conditions, including (Ear, Nose and Throat) ENT, orthopaedic, dental, plastic, trauma, cardiothoracic, ophthalmic, and general paediatric surgery [1]. The particular needs must be recognised whenever paediatric patients undergo anaesthesia and surgery. They should be managed in special facilities and looked after by staff with appropriate experience and training [2].

Paediatric patients are not small adults: they differ physiologically, emotionally, and socially. Doses of drugs and fluids need to be precisely calculated, and anaesthesia equipment for more minor paediatric patients differs from that used in older paediatric patients and adults [3].

The cardiovascular system in Paediatrics shows a higher cardiac output and oxygen consumption per kilogram than in adults, they support this by a higher baseline heart rate [4], as shown in Table 1. The tidal volume and dead space are equally unchanged in the respiratory system, where the minute volume is high due to increased respiratory rate [5].

Table 1: Cardiovascular vital signs in paediatrics [6].

Temperature regulation, hypothermia can result in delayed recovery, cardiac irritability and respiratory depression due to cold intravenous fluids, dry anaesthesia gases, and wound exposure; paediatrics lose heat to the environment more readily than adults due to increased body surface area per kilogram. Therefore, it is essential to prevent heat loss in a warm operating room environment [7].

Pharmacologic Differences in Paediatric include that drugs are generally dosed on a per kilogram basis. Additionally, neonates are more sensitive to opiate analgesics during the first four weeks of life, leading to an increased risk of hypoventilation. The volume of distribution for most of the drugs, including muscle relaxants, is increased in paediatric patients so that a regular dose can lead to a lower plasma level than in adults. However, paediatric patients are sensitive to the effects of muscle relaxants, so a lower plasma level leads to the same effective dose [8].

Fluid Management Divisions are deficit therapy, maintenance therapy, and replacement therapy [9].

Fluid deficit therapy refers to managing fluid and electrolyte losses that occur before presentation for surgery, and they are three components; estimation of dehydration severity, determination of fluid deficit type, and deficit repair [10].

Dehydration severity is usually estimated from history and clinical evaluation. Investigations that may confirm the dehydration include serum osmolality, serum sodium, acid-base status, serum pH, base deficits, and serum potassium compared with the pH and urine output (rule out acute tubular necrosis) [11].

The biochemical investigation will reveal whether the type of dehydration is hyponatraemia (serum osmolarity < 270 mOsm/L, serum Na < 130 mEq/L), isonatraemic (serum osmolarity 270-300 mOsm/L, serum Na 130-150 mEq/L) or hypernatremic (serum osmolarity > 310 mOsm/L, serum Na > 150 mEq/L) [12].

Table 2: Holliday and Segar’s and modified by Oh Replacement therapy (Measured Losses) [13].

Maintenance fluid requirements have been calculated in several ways, including caloric expenditure and body surface area [14]. The most straightforward and commonly used formula was advised by Holliday and Segar and modified by Oh, as seen in Table 2 [13]; it relates to energy (caloric) expenditure and, therefore, the fluid volume required to weigh in kilograms [13].

Fluid loss replacement should be with an isotonic fluid, e.g., normal saline, a colloid, or blood, to replace haemorrhage without resulting in low haemoglobin levels [15]. Fluid evaporation from an open wound or third space loss varies depending on the operation and may range from 5 to 20 ml/kg/ hour. Loss of fluid via the lungs due to humidification of inspired gas may be reduced using a circle system or heat and moisture exchange filters in the breathing circuit [16].

The allowable blood loss = Estimated blood volume x Hb (current) - Hb (acceptable)/Hb (mean) [17].

Neonates (up to 44 weeks post-conceptual age) have a different fluid requirement; they are physiologically “waterlogged” but lose up to a tenth of their body weight in the first week of life. Premature or low birth new-borns have a greater surface area to weight ratio, lose more fluid by evaporation, and, as a result, require more replacement fluid (Table 3) [18].

Table 3: The fluid requirement in paediatric surgical unit guidelines, Sheffield Paediatric Patients’ Hospital [19].

Glucose may be required to prevent hypoglycaemia while the child is starved, although this appears to be less problematic than what was previously thought [19].

Body physiology about glucose showed that diurnal variation in cortisol levels affects blood glucose levels. These are higher in the morning than in the afternoon. Paediatric patients who starved overnight have more elevated blood glucose than those who starved during the day. The surgery’s stress and starvation increase the blood glucose level in paediatric patients as young as two weeks; this occurs even if no glucose-containing fluids are given. Administration of glucose will exacerbate this even further [20].

Glucose requirement in paediatrics may be calculated on an mg/kg/hour basis; glucose 120 mg/kg/hour maintains blood glucose level within a normal range and prevents lipid mobilisation. If solutions containing less than 5% glucose are unavailable, glucose may be given as an individual infusion or added to normal saline or combined saline and lactated ringer’s [21].

Patients at risk of hypoglycaemia or hyperglycaemia should monitor their blood glucose regularly.

Anaesthesia and surgery can induce significant lifethreatening hypoglycaemia. However, intra-operative hypoglycaemia is extremely rare in paediatric patients. On the other hand, hyperglycaemia is more commonly encountered during anaesthesia and surgery because intraoperative glucose uptake by the muscle is reduced [22]. The response to anaesthesia, surgery, anxiety and pain further increases blood sugar levels. The impaired effectiveness of insulin may further aggravate hyperglycaemia during anaesthesia. A glucose administration rate of more than 10 mg/kg/min may overwhelm the renal threshold and result in glucosuria and osmotic diuresis. With decreased tolerance to exogenous glucose and increased endogenous glucose production, a solution containing low glucose concentrations in a balanced salt solution may be required as a maintenance fluid. The replacement fluid should either be free of glucose or should not have more than 1% glucose. The present recommendations include using low glucose-containing solutions for maintenance fluid therapy to ensure adequate blood sugar levels without inducing hyperglycaemia [23].

Aim of the Work

This study evaluates the use of three fluid regimens of isotonic solutions, including glucose 1%, 2.5% and 5%, during paediatric anaesthesia to focus on changes in blood glucose concentrations, electrolytes, and acid-base status.

Patients

The study was carried out in Alexandria University Hospital after obtaining approval from the medical ethics and patient safety committee of the faculty of medicine and informed written consent from all patient’s guardians. The study was done on 30 paediatric patients who fasted for 6 hours after allowing 2 hours for free fluids, aged 2-4 years (the medical statistic department calculated the sample size, medical research institute by using NCSS2004 and PASS2000 Program), scheduled for minor non-haemorrhagic elective surgery under general anaesthesia as shown in the following flow diagram.

Study flow diagram.

Exclusion Criteria

1. Diabetic patients.
2. Patients who have a nutritional disorder.
3. Patients who are having major cardiac surgery.
4. Patients who are having a haemorrhagic operation.
5. Patients who are on total parenteral nutrition.
6. Patients who have an operative duration of less than one hour.

Methods

Pre-Operative Assessment

After obtaining informed written consent from guardians of all patients included in this study, they were assessed thoroughly by a detailed medical and surgical history taken from guardians, followed by a complete clinical examination in conjunction with checking the routine laboratory investigations including Hb%, Hct%, blood glucose level, urea, serum creatinine, Na, and K.

Method of solution preparation (one litre): The Infection Control Department has instructed to prepare any given solutions under a completely closed system to prevent any infection risk.

1. Glucose 1% isotonic solution: [G1% + NaCl 0.7% ]= (200 cc G5% + 800 cc Normal saline0.9%), Osmolarity around 289.77 mOsm/L.
2. Glucose 2.5% isotonic solution: [G2.5% +NaCl 0.45%]=( 500 cc G5% + 500 cc Normal saline0.9%),  Osmolarity is around 280 mOsm/L.
3. Glucose 5% isotonic solution: [G5% + NaCl 0.15%]=( 700 cc G5%+150 cc G10% + 150 cc Normal saline0.9%), osmolarity around 303.2 mOsm/L. [24].

Premedication

All patients were pre-medicated with midazolam (0.3-0.5 mg/kg) intra- nasal 15 minutes before arrival at the operation room. Monitoring: On arrival at the theatre, the patient was connected to the standard monitoring, including lead п electrocardiograph, noninvasive arterial blood pressure, pulse oximetry and axillary or rectal probe for temperature monitoring using the Hewlett Packard (HP) viridian 24 multi-channel monitors. Induction: Before induction of anaesthesia, patients were pre-oxygenated with FiO² 1 for at least 3 minutes; then sevoflurane mask in 100% oxygen was used to insert IV access, then Induction of anaesthesia was established by the fentanyl 1ug/kg followed by (0.1-0.15mg/kg) cis-atracurium to allow proper placement of suitable size LMA and to allow pressure controlled mechanical ventilation.

Given solutions

Group (I) received glucose 1% isotonic solution, group (II) received glucose 2.5% isotonic solution, and group (III) received glucose 5% isotonic solution. The fluid requirement and replacement in the three groups were managed according to fasting time, maintenance and losses based on the (4:2:1 rule) [25].

Measurement Parameters

a)       Haemodynamics: have been recorded as average heart rates recorded throughout the operation, and the mean arterial blood pressures are tabulated to be discussed later.

b)       Laboratory investigations: blood glucose level, blood gases, Na, K before and after infusion.

Sampling Time

The blood glucose levels, Na, K, and blood gases were sampled just before starting infusion and beginning to awaken the patient; another sample during operation for blood glucose level was taken to stop glucose infusion if hyperglycemia occurred. Recovery: By the end of the procedure, the patient started to recover by stopping Sevoflurane inhalation, reversing the muscle relaxant with neostigmine (30-50 ug/kg) preceded by atropine (0.01 - 0.02 mg/kg) and regaining spontaneous breathing oral suction and removal of the inflated LMA, then face mask with FiO² 1 is allowed until the patient starts to cry clearly with 100% oxygen saturation on the monitor to be discharged from the operating room safely.

Statistical Analysis

Data were fed to the processor using the Predictive Analytics Software (PASW Statistics 18).

Measures such as median, minimum, and maximum values were used to describe the quantitative data, along with the mean and standard deviation.

The normality of the distributions of the quantitative variables was assessed by applying the Kolmogorov-Smirnov and Shapiro-Wilk tests. The D’Agstino test was used if there was a doubt between the two previous tests. If it shows normal data distribution, parametric tests were applied. If the data were abnormally distributed, non-parametric tests were used.

The Mann-Whitney test was used to analyse two independent populations for abnormally distributed data. The Mann-Whitney Suppose more than two populations were analysed Kruskal Wallis test to be used. Wilcoxon Signed Rank test was assessed for two periods. The same case test was used to analyse two independent populations for an abnormally distributed data massive group.

Massive test results are quoted as two-tailed probabilities. The obtained results were evaluated at a significance level of 5% [26].

Results

This study was conducted on 30 ASA I physical status paediatric patients aged 2 to 4 years and scheduled for surgical correction of congenital hypospadias. Intravenous solutions of different glucose concentrations and the patient’s data in each group were recorded, analysed, and tabulated.

As regards the loss volumes from the patient, there were no significant differences as all patient losses were around 30 to 50ml of blood, which was of no significant difference as the P

value was 0.167. As regards the total infusion volume of the given fluid, which was around 300 to 350 ml statistically, no significant differences were reported between each group and the other group as the P value was 0.944 (Figure 1,2).

Figure 1: Comparison between the studied groups according to groups, as seen in the following (Tables 4-6).

Figure 2: Comparison between the studied groups according to Infusion volume.

The following tables show the distribution of the studied cases according to investigations immediately pre-operative in 3 losses.

Table 4: The studied cases according to investigations immediately pre-operative in group I.

Table 5: Studied cases according to investigations immediately pre-operative in group II.

Table 6: According to investigations, the studied cases were immediately pre-operative in group III.

The following tables show the distribution of the studied cases according to investigations immediately post-operative in 3 groups, as seen in the following (Tables 7-9).

Table 7: The studied cases according to investigations immediately post-operative in group I.

Table 8: According to investigations, the studied cases were immediately post-operative in group II.

Table 9: According to investigations, the studied cases were immediately post-operative in group III.

As regards the comparison between the studied groups according to separate investigation immediately post-operative, there were no significant differences between them except for RBG results which resulted in substantial differences as the P value was <0.001, as seen in (Table 9).

By comparing the results of the three groups pre and post-operatively, there was statistically no significant differences between them except for the RBG results, which revealed significant differences between the three group as the P value was <0.05, as seen in Table 10 and Figure 3-8. In group II, the RBG level increased 1.5-fold the preoperative value, and in group III RBG level increased by 2.5-fold the preoperative value

Table 10: Comparison between the studied groups according to RBG (mg/dl) pre- and post-operatively.

P*: p-value for Wilcoxon signed ranks test between pre- and post-operative.

 Figure 3: Comparison between the studied groups according to Na results.

 Figure 7: Comparison between the studied groups according to PaCO₂ results.