Effects of Pneumoperitoneum on Splanchnic Oxygenation during Abdominal Laparoscopic Surgery in Paediatric Patients: A prospective, Observational Study.

OBJECTIVE: Pneumoperitoneum can cause disruption in splanchnic perfusion. This study aims to investigate effects of pneumoperitoneum on splanchnic oxygenation during abdominal laparoscopic surgery in paediatric patients with NIRS (Near-Infrared Spectroscopy).
MATERIAL AND METHODS: A total of 45 patients between 1 and 4 years of age with ASA physical status I-II and scheduled to undergo abdominal laparoscopic surgery under general anaesthesia were enrolled in this prospective, observational surgery. No premedication was used. Standard monitoring and regional splanchnic saturation (rSPcO2), regional cerebral oxygen saturation (rScO2) with NIRS were established before anaesthesia. Anaesthesia was induced with an inhalational agent and maintained with an oxygen/air mixture and sevoflurane. Peripheral oxygen saturation (SPO2), rSPcO2, rScO2, heart rate (HR), mean arterial pressure (MAP), end tidal CO2 (Et-CO2), and insufflation pressure (IP) were continuously monitored during administration of anaesthesia and recorded. After intubation (baseline T0); before CO2 insufflation induced pneumoperitoneum (PP) (T1); CO2 PP insufflation (T2); 5 minutes after PP insufflation (T3); 10 minutes after PP insufflation (T4); 15 minutes after PP insufflation (T5); 20 minutes after PP insufflation (T6); 30 minutes after PP insufflation (T7), 60 minutes after PP insufflation (T8), and after desufflation (T9). Bradycardia and hypotension were recorded. Paracetamol IV 10 mg kg-1 was applied for post-operative analgesia. p<0.05 wasconsidered significant.
RESULTS: HR, rScO2, and rSPcO2 decreased at all measured time intervals when compared to T0 (p<0.01) MAP decreased at T1 compared to T0 (p<0.001). Et-CO2 increased at T3-T4-T5-T6 compared to T0 (p<0.001).
CONCLUSION: We found that pneumoperitoneum reduced splanchnic oxygenation during laparoscopic abdominal surgery in paediatric patients, which was measured using NIRS. © Copyright 2021 by Turkish Anaesthesiology and Intensive Care Society.

Introduction

Laparoscopic surgery is being routinely performed in children for abdominal surgical interventions. Small-sized wound site, faster recovery, less post-operative pain, early mobilisation, a less risk of brid-ileus development, and fluid loss are the most common advantages of this technique (1). Despite its advantages, pneumoperitoneum (PP); increased intra-abdominal pressure (IAP) and CO2 insufflation lead to physiological changes. Decrease in respiratory compliance, functional residual capacity and deterioration of oxygenation, hypercarbia and related acidosis, increased intracranial pressure and increased release of vasopressin can cause regional blood flow changes, reduction of hepatic, splanchnic, renal blood flow and reduced cerebral and splanchnic oxygenation (2, 3).

Splanchnic circulation receives 30% of cardiac output and has a regional storage function. It is known that the first signs of increased intraabdominal pressure arise with the impairment of splanchnic perfusion (4). Intestinal ischemia, decreased gastric perfusion, and decreased portal circulation have been reported due to increased IAP (5, 6).

Mesenteric arterial blood flow and gastric pH measurements are used to indicate splanchnic macrocirculatory changes during CO2 pneumoperitoneum (7). Gastric pH measurements and mixed venous oxygen saturation are used to show splanchnic perfusion, which are invasive methods requiring catheterization (7–9). Near-infrared spectroscopy (NIRS) is a non-invasive method for measuring local haemoglobin oxygen saturation in tissue (10). NIRS has been used for measuring cerebral regional oxygen saturation (11, 12). In neonatal intensive care units, abdominal NIRS measurements are used to monitor changes in perfusion and oxygenation of the intestinal and splanchnic tissue (13, 14).

Splanchnic organs lie near the skin surface in children and are more easily accessible with NIRS somatic sensors with an average penetration depth of 2 cm (15). In the existing literature, there is no study investigating the splanchnic oxygenation during pneumoperitoneum in children.

We aimed to investigate the effects of pneumoperitoneum on splanchnic oxygenation during abdominal laparoscopic surgery in paediatric patients with NIRS (Near-Infrared Spectroscopy).

Methods

The study was approved by the Sisli Hamidiye Etfal Training and Research Hospital Ethics Committee (SEEAH, 948, 06/02/2018). A total of 45 patients between the age of 1 and 4 years with ASA (American Society of Anaesthesiologists) physical status I–II and scheduled to undergo abdominal laparoscopic surgery under general anaesthesia in paediatric surgery clinic between February 2018 and June 2018 were enrolled in this prospective, observational study. Written informed consent from each patients’ guardian was received. The exclusion criteria were the presence of cardiovascular disease, respiratory disease, and hemodynamic instability. The study was performed according to the Declaration of Helsinki.

Anaesthesia protocol

No premedication was applied to patients before surgery. Standard monitoring was established in the operating room with peripheral oxygen saturation SPO2, non-invasive arterial pressure, electrocardiography, End-tidal CO2 (Et-CO2) (CardiocapII; Datex, Helsinki, Finland), and rSPcO2 and rScO2 were measured using a cerebral/somatic near-infrared spectroscopy (NIRS) (model INVOS 5100; Covidien, Mansfield, MA. INVOS™ OxyAlert™ NIRS Sensors for infants and neonates). Demographic data: age, gender, height, weight, ASA and operation types, and haemoglobin and haematocrit values were recorded before surgery. Cerebral sensor was placed on the left lateral forehead, and one somatic sensor was placed on anterior abdominal wall above the umbilicus for measurement of cerebral and splanchnic oxygenation before anaesthesia induction. Anaesthesia was induced with an inhalational 8% sevoflurane 50/50% oxygen–air mixture. An intravenous line was applied and 1–2 mcg kg−1 fentanyl, 0.6 mg kg−1 rocuronium were administered. After tracheal intubation, anaesthesia was maintained with an oxygen/air mixture and 2% sevoflurane. Patients were ventilated by volume-controlled mechanical ventilation with a tidal volume 6–8 mL kg−1, and the respiratory rate was adjusted to achieve an end-tidal CO2 level of 32–35 mmHg. The PP CO2 pressure which ranged from 8 to 10 mmHg was achieved with a CO2 insufflation flow rate of 1–5 L min−1.

Intraoperative rScO2, rSPcO2, SPO2, HR, MAP, Et-CO2, and insufflation pressure were monitored continuously and recorded; one minute after intubation (baseline T0); before CO2 insufflation induced pneumoperitoneum (PP) (T1); CO2 PP insufflation (T2); 5 minutes after PP insufflation (T3); 10 minutes after PP insufflation (T4); 15 minutes after PP insufflation (T5); 20 minutes after PP insufflations (T6); 30 minutes after PP insufflation (T7), 60 minutes after PP insufflation (T8) and the 1 minute after desufflation (T9). Operation and anaesthesia time were recorded.

Side effects, such as bradycardia and hypotension were recorded. Bradycardia and hypotension defined with a rate of 20% under baseline and were treated with atropine 0.01 to 0.03 mg kg−1 IV and ephedrine 0.2 mg kg−1 IV, respectively.

Patients received paracetamol IV 10 mg kg−1 10 min before end of the surgery. At the end of the surgery, 100% O2 was started, antagonization of neuromuscular blocker was achieved with 0.015 mg kg−1 of atropine and 0.035 mg kg−1 of neostigmine.

Statistical analysis

Statistical Package for the Social Sciences version 15.0 for Windows (SPSS Inc., Chicago, IL, USA) statistical package was used for statistical analysis. Repeated analysis of variance (ANOVA) was used to test for any change in rScO2, rSPcO2 during the study time points. The rScO2, rSPcO2 changes during pneumoperitoneum were compared using a paired t test. All data were presented as the mean ± standard deviation of median with range. Descriptive statistics are given as number and percentage for categorical variables, mean ± standard deviation, minimum, maximum, and 95% CI for numerical variables. Dependent group comparisons were made by the Wilcoxon test because the differences of the numerical variables did not meet the normal distribution condition. Bonferroni correction was interpreted. Statistical significance was accepted as p<0.05.

Results

Demographic data: age, gender, height, weight, ASA and operation time, anaesthesia time, operation types, and haemoglobin and haematocrit values are presented in (Table 1).

Table 1

Demographic data, operation time, operation types, and haemoglobin and haematocrit values

	Mean±SD	Min–Max
Age (month)	30.08±5.9	12–48
Gender, n (%)
Male	18 (40.0)
Female	27 (60.0)
Height (cm)	86.8±13.4	60–116
Weight (kg)	16.3±4.3	10–21
ASA, n (%)
1	42 (93.3)
2	3 (6.7)
Operation time (min)	32.9±11.6	20–55
Pneumoperitoneum time (min)	25.5±9.3	15–60
Haemoglobin	12.4±1.0	10–14.5
Haematocrit	37.9±3.7	31–49
Operation types n (%)
Appendectomy	13 (28.8)
Inguinal hernia repair	26 (57.7)
Undescended testicles	6 (13.3)

HR values were found to decrease at T1-T2-T3-T4-T5-T6 and T9 compared to T0 (p<0.001, p<0.002, p<0.001, p<0.001, p<0.001, p<0.001, p<0.001). MAP value was found to be significantly decreased at T1 as compared to T0 (p<0.001) (Figure 1). SpO2 values did not change at all measured time intervals when compared to T0 (Figure 1). Et-CO2 values were increased at T3-T4-T5-T6 and T9 when compared to T0 (p<0.001, p<0.001, p<0.001, p<0.002, p<0.001) (Figure 1).

Figure 1

HR (beat min−1), MAP (mm Hg−1), SPO2, Et-CO2

rScO2 decreased at all measured time intervals when compared to T0 (p<0.001, p<0.001, p<0.006, p<0.005, p<0.006, p<0.005, p<0.005, p<0.01, p<0.005, p<0.006, p<0.01) (Table 2) (Figure 2).

Table 2

rScO2 Values

		N	Mean±SD	95% CI
rScO2	T0	45	83.5±8.4	79.1–87.1
	T1	45	81.4±8.9*	76.7–84.1
	T2	45	80.1±9.1*	74.6–83.7
	T3	45	80.2±9.3	73.4–84.5
	T4	45	80.2±8.8*	73.5–83.6
	T5	43	79.7±9.6	76.8–82.7
	T6	32	79.8±8.9	76.6–83
	T7	14	77.6±9.9	71.9–83.3
	T8	4	78.5±10.4	61.9–95.1
	T9	45	81.4±9.2	78.1–83.8

p<0.0055

Figure 2

rScO2 and rSPcO2

rSPcO2 decreased at all measured time intervals, except T9 when compared to T0 (p<0.01-p<0.002-p<0.019-p<0.005-p<0.002-p<0.01-p<0.01-p<0.01) (Table 3) (Figure 2). Insufflation pressure values are presented as mean+ SD deviation (Table 4).

Table 3

rSPcO2 Values

		N	Mean±SD	95% CI
rSPcO2	T0	45	82.4±8.8	76.3–84.5
	T1	45	80.6±8.6	74.3–83
	T2	45	79.4±7.9*	81.9–80.1
	T3	45	79.4±8.7	76.4–83.9
	T4	45	79.2±9.2*	76.9–83.9
	T5	44	78.7±9.4*	75.8–81.6
	T6	36	79.4±10.6	75.8–83
	T7	12	79.9±12.4	72.9–88.7
	T8	4	80.4±12.1	64.8–103.2
	T9	45	82.5±8.2	79.7–84.8

p<0.0055

Table 4

Insufflation pressure (IP) (mm Hg)

		N	Mean±SD	95% CI
IP	T2	22	10.3±2.1	9.3–11.3
	T3	43	10.6±2.1	9.6–11.5
	T4	42	10.6±2.1	9.9–11.2
	T5	37	10.5±2.0	9.8–11.2
	T6	28	10.6±2.3	9.7–11.5
	T7	14	10.6±2.5	9.1–12
	T8	4	10.3±1.5	9.9–11.6

There were no side effects shown (Figure 1).

Discussion

Laparoscopic surgery is being increasingly used in paediatric patients. In the existing literature, there is no study that has investigated the splanchnic area oxygenation during pneumoperitoneum in children. During follow-up with perioperative NIRS, it has been found that abdominal pneumoperitoneum reduces splanchnic oxygenation in paediatric patients during abdominal laparoscopic surgery.

During laparoscopic surgery, PP reduces the venous return by inferior vena cava compression. It causes significant reduction in contractility, left ventricular compliance, and cardiac output (16). Gentili et al. (17) revealed a significant decrease in cardiac function and volume in 20 healthy children who had undergone laparoscopic surgery at an intraabdominal pressure of 10 mmHg. Pelizzo et al. (11) compared laparoscopic and open techniques in children, and they found a decrease in the blood pressure and elevated HR in the laparoscopic surgery group. In another study by the same authors, high HR were found in children who underwent laparoscopic surgery, and it was inferred to be a response to CO2 elevation and catecholamine discharge (18). In this study, while MAP was stable at all measurement times, a slight decrease was observed during induction; no PP-related change was observed. This can be attributed to the effects of anaesthetic drugs after induction and adequate fluid replacement in pre-operative and perioperative periods. HR decreased with insufflation, and the continued to decrease until the end of the operation. It could be an effect of increased vagal tone due to increased intraabdominal pressure.

PP can cause adaptive changes in the cerebrovascular system and decrease the brain oxygenation (19). Different results have been reported on the relationship between laparoscopic surgery and regional effects on cerebral oxygenation in children. De Waal et al. (20) demonstrated that insufflation of CO2 at low IAPs (8 mmHg) in children causes increase in rSO2. Westgarth-Taylor et al. (21) found an increase in cerebral oxygenation after insufflation in paediatric patients who had undergone laparoscopic surgery. In the other two studies, they found no change in cerebral oxygenation due to pneumoperitoneum compared to the open technique (22, 23). Tsypin et al. (24) reported an average reduction of 3% in regional cerebral tissue saturation in children during gynaecological laparoscopic interventions. Pelizzo et al. (11) observed a decrease in the cerebral oxygenation with insufflation at 10 IP in laparoscopic inguinal surgery. In case of 20% or more decrease in perioperative cerebral oxygenation, follow-up of neurological functions after surgery is recommended (10). In this study, rScO2 values were observed to be 79 on an average during pneumoperitoneum, and it was lower compared to the baseline values. Increased ICP with decreased cardiac output and oxygen delivery, hypercarbia-related vasodilation can be explained by the decrease in rScO2 and disruption of cerebral perfusion during PP. There was also a decrease in HR; however, this did not impair hemodynamic stability.

NIRS can be used as a routine monitoring technique to evaluate somatic tissue oxygenation especially splanchnic area in paediatric patients. Bailey et al. (25) reported mean rSPcO2 values of 69.9±12.1 on the first day of life, and this value increased with gestational age. Some authors have suggested the use of splanchnic cerebral oxygenation ratio (SCOR) to estimate splanchnic ischemia and rSO2 was reported to be more effective in determining the mesenteric flow rate than mesenteric Doppler (26–28). Bhalala et al. (29) reported a decrease of 20 % and more compared to the baseline values. NIRS was recommended to determine the oxygen demand of regional oxygen saturation (rSO2), transfusion requirement, and in the diagnosis of necrotizing enterocolitis (NEC) in neonatal intensive care units (5, 30–32). Kaufman et al. (33) found a strong correlation between splanchnic rSO2 and gastric pH measurement, mixed venous oxygen saturation, and serum lactate levels in 20 infants who underwent congenital cardiac surgery. It was reported that splanchnic rSO2 measurement was rapid, reliable, and a non-invasive method for the evaluation of splanchnic oxygenation and perfusion.

We investigated the decrease in rSPcO2 values during PP compared to the baseline. rSPcO2 was observed to be 78 on average during PP. Decreased rSPcO2 values can be explained by impaired microcirculation, decreased organ blood flow, and splanchnic ischemia during CO2 insufflation.

There are some limitations to this study. We could not compare rScPO2 values in open surgical technique because abdominal surgical interventions are routinely performed by laparoscopic technique in paediatric patients in our hospital.

Tissue ischemia and impaired organ function can be a cause of laparoscopy-associated morbidity and mortality (34–36). In conclusion, we determined that pneumoperitoneum reduces the cerebral and splanchnic oxygenation measured with NIRS during laparoscopic abdominal surgery in paediatric patients. We recommend close and optimal perioperative and post-operative monitoring with NIRS, which can reduce laparoscopic surgery-related complications.

It is known that the first signs of increased intraabdominal pressure arise with the impairment of splanchnic perfusion.

In neonatal intensive care units, abdominal NIRS measurements are used to monitor changes in perfusion and oxygenation of the intestinal and splanchnic tissue.

In the existing literature, there is no study investigating the splanchnic area oxygenation during pneumoperitoneum in children.

We aimed to investigate the effects of pneumoperitoneum on splanchnic oxygenation during abdominal laparoscopic surgery in paediatric patients with NIRS.

We determined that pneumoperitoneum reduces splanchnic oxygenation during laparoscopic abdominal surgery in paediatric patients which was measured with NIRS.