Anaesthetic Management and Physiologic Effects of Pneumoperitoneum in Patients With Chronic Obstructive Pulmonary Disease Undergoing Laparoscopic Cholecystectomy

Objective: This study aimed to assess the physiological changes and clinical outcomes in patients with chronic obstructive pulmonary disease (COPD) undergoing laparoscopic cholecystectomy. Methods: This prospective cohort study included 50 patients of the American Society of Anesthesiology (ASA) physical status I and II with mild to moderate COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I-II) scheduled for laparoscopic cholecystectomy. We monitored heart rate, mean arterial pressure, end-tidal carbon dioxide (EtCO2), arterial carbon dioxide (PaCO2), and bicarbonate (HCO3) levels at baseline, 30 minutes after induction or 15 minutes post-insufflation, 15 minutes post-deflation, and 60 minutes post-operative. Perioperative complications and post-operative recovery characteristics were also observed. Descriptive statistics were used to summarise the demographic and clinical characteristics of the patients. The correlation between HCO3 and EtCO2 was plotted on a scatterplot, and Pearson’s correlation ‘r’ was calculated. The changes in physiological parameters over time were analysed using a paired t-test. A p-value of less than 0.05 is considered statistically significant. Results: We observed a statistically significant but transient increase in heart rate, mean arterial pressure, and EtCO2 at 30 minutes after induction or 15 minutes post-insufflation, which returned to baseline levels within 15 minutes of deflation. Similarly, arterial CO2 and bicarbonate levels were also significantly increased at 15 minutes post-insufflation, yet remained within the normal physiological range. The study reported no serious perioperative complications, and all patients had an uneventful recovery. Conclusion: While patients with mild to moderate COPD can experience transient physiological changes during laparoscopic cholecystectomy, these changes are generally well-tolerated and not associated with adverse clinical outcomes. Therefore, laparoscopic cholecystectomy can be considered a safe procedure in these patients. Future research should focus on the implications and safety of this procedure in patients with severe COPD.


Introduction
Chronic obstructive pulmonary disease (COPD) is a prevalent and debilitating disease characterised by persistent respiratory symptoms and limited airflow due to abnormalities in the airways or alveoli.This condition, primarily caused by significant exposure to noxious particles or gases, poses a considerable threat to global health.The Global Burden of Disease Study estimates COPD to be the third leading cause of death worldwide by 2020, emphasising the gravity of its morbidity and mortality rates [1].The diagnostic criteria for COPD include a ratio of the forced expiratory volume in 1s (FEV1) to forced vital capacity (FVC) less than 0.7, confirming the presence of airflow limitation that is not fully reversible [2].Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines classify COPD into mild (FEV1 ≥ 80% predicted), moderate (50% ≤ FEV1 < 80%), severe (30% ≤ FEV1 < 50%), and very severe (FEV1 < 30%) disease [3].
The increasing prevalence of COPD has imposed a growing burden on surgeons and anaesthesiologists who now manage a larger volume of high-risk respiratory patients [4].Especially when it comes to laparoscopic procedures, COPD patients present unique challenges.Traditional surgical approaches often leverage general anaesthesia (GA), where patients are rendered unconscious during surgery.However, emerging

Participants
The participant pool consists of adult COPD patients (aged 35-65 years) who were diagnosed based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria, with an FEV1/FVC ratio of less than 0.7 post-bronchodilator.GOLD 1 is classified as mild with FEV1 ≥ 80% predicted and GOLD 2 as moderate with 50% ≤ FEV1 < 80% predicted [3].The participants were all scheduled for elective laparoscopic cholecystectomy.Patients with any contraindication for laparoscopic surgery, patients who convert to open surgery, those with cardiac diseases, or any other systemic disease were excluded from the study.

Anaesthesia technique
All the patients included in the study were educated about lung volume expansion manoeuvres like voluntary deep breathing and incentive spirometry preoperatively to institute it in the post-operative period for early recovery.A wide-bore cannula was taken, and intravenous fluid was started.Left or right radial artery cannulation with a 22-gauge cannula was performed under local anaesthesia after carrying out Allen's test.Patients were then taken to the operating room, and standard monitoring was applied.Patients were preoxygenated using 100% oxygen for three to five minutes, and anaesthesia was induced with 0.05 mg/kg injection midazolam IV 1-2 μg/kg, injection fentanyl IV 2-3 mg/kg, injection propofol IV in suitable doses; following loss of verbal command, non-depolarising muscle relaxant injection vecuronium was given IV at a dose of 0.08-0.12mg/kg bag and mask ventilation was done for three minutes followed by orotracheal intubation with suitable size endotracheal tube.Maintenance was done with 1%-2% isoflurane in a mixture of 50% oxygen/50% medical air with intermittent boluses of injection vecuronium and fentanyl.The pneumoperitoneum was created by peritoneal insufflation with carbon dioxide and maintains an abdominal pressure between 10 and 12 mm of Hg all the time.Laparoscopic cholecystectomy was performed according to a standard four-port technique in all the patients.Isoflurane was discontinued at the time of skin closure, and flows were increased to 10 litres/min with a fraction of inspired oxygen (FiO 2 ) to 100%.One gram of injection paracetamol was given intravenously, and an injection of 0.25 bupivacaine was infiltrated at all four ports during closer.Residual muscle relaxation was antagonised with 0.01 mg/kg glycopyrrolate and 0.04-0.07mg/kg neostigmine at the end of the operation.

Variables
The main variables studied include heart rate, mean arterial pressure, arterial and end-tidal CO 2 (PaCO 2 and EtCO 2 ), and bicarbonate (HCO 3 ).These are measured at baseline (before induction of anaesthesia), 30 minutes after induction or 15 minutes post-insufflation, 15 minutes post-deflation, and 60 minutes postoperative.Other variables, such as demographic data (age, sex, BMI), type of anaesthesia used, and perioperative variables (duration of surgery, intraoperative complications) are also collected for comprehensive analysis.

Data sources/measurement
Clinical assessments and measurements are made using standard hospital equipment and protocols.Arterial blood gases are collected and analysed using a blood gas analyser.End-tidal CO 2 (EtCO 2 ) is measured through capnography, a standard monitor used during anaesthesia.

Bias
All the patients undergoing laparoscopic cholecystectomy were evaluated on an objective checklist comprising the inclusion and exclusion criteria sets for this study.All patients fulfilling the criteria and consenting to participation were included in the study without fail to limit selection bias.Observer bias was limited by having a blinded assessor analyse the recorded data.

Study size
The study size was determined using power analysis based on previous studies examining similar physiological parameters during laparoscopic surgery in patients with COPD.

Statistical methods
Descriptive statistics are used to summarize the demographic and clinical characteristics of the patients.The correlation between HCO 3 and EtCO 2 was plotted on a scatterplot, and Pearson's 'r' was calculated.The changes in physiological parameters over time are analysed using a paired t-test.A p-value of less than 0.05 is considered statistically significant.All analyses are conducted using a statistical software package.

Ethical considerations
The study protocol is approved by the hospital's institutional ethics committee Dr. RMLIMS, Lucknow, with reference no.ICC No. 66/19, and all patients provided written informed consent before participation.The study is carried out in compliance with the principles of the Declaration of Helsinki and local regulations.

Results
The study sample included 50 patients with COPD undergoing laparoscopic cholecystectomy.The mean age was 56 years, with a balanced gender distribution having 54% males and 46% females, and the mean body mass index (BMI) was approximately 28 kg/m 2 .Most patients (72%) had a GOLD stage II (moderate COPD), with the rest (28%) being stage I (mild COPD) (Table 1).

TABLE 2: Showing changes in heart rate (HR) and mean arterial pressure (MAP) over time
Blood pH showed a small but statistically significant decrease at 30 minutes after induction, i.e. 15 minutes post-insufflation from 7.35±0.17to 7.29±0.13with a mean difference of 0.068 (p-value < 0.001) but recovered at somewhat 60 minutes post-operatively, while bicarbonate (HCO 3 ) levels showed slight increase all over time from baseline but not significant (p-value>0.05)always within the normal physiological range (Table 3).EtCO 2 and PaCO 2 levels showed a significant increase 15 minutes post-insufflation (p-value<0.05),but these changes were clinically insignificant as they remained within the normal physiological range.There was no significant correlation between pre-and post-operative EtCO 2 and HCO 3 with a Pearson correlation 'r' of 0.002 and 0.032 (     Complications were minimal, with only one case of delayed emergence and one case of bronchospasm among the studied patients.No serious perioperative complications were observed, and all patients had an uneventful recovery.
relationships at present or within the previous three years with any organizations that might have an interest in the submitted work.Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

TABLE 1 :
Demographic variablesBMI: body mass index, ASA: American Society of Anesthesiology, GOLD: Global Initiative for Chronic Obstructive Lung Disease.
Throughout the procedure, heart rate (HR), mean arterial pressure (MAP), and end-tidal CO 2 (EtCO 2 ) showed a statistically significant increase from baseline at 15 minutes post-insufflation, i.e. 30 minutes post-induction (p-value < 0.05).However, these values returned to baseline levels within 15 minutes of deflation.During the study, a notable increase in HR was observed 30 minutes after induction of anaesthesia, i.e. from 81.21±6.17 to 93.82±6.92 with a mean difference of -12.60 (p-value < 0.001), which normalised 60 minutes post-operatively (p-value > 0.05).MAP showed little variation over time except at 15 minutes post-insufflation when it was significantly increased (p-value < 0.05) (Table2).

TABLE 3 : Showing changes in pH and HCO3 over time
The end-tidal CO 2 (EtCO 2 ) showed a statistically significant increase from baseline at 15 minutes postinsufflation or 30 minutes after induction, i.e. from 36.50±4.29 to 39.51±3.39 with a mean difference of -3.01 (p-value < 0.001).However, these values returned to baseline levels within 15 minutes of deflation and decreased to near pre-operative levels 60 minutes post-operatively.Arterial CO 2 (PaCO 2 ) levels showed fluctuation over the course of the procedure, at 15 minutes post-insufflation, i.e. 30 minutes after induction, it increased significantly from baseline 43.45±4.11to45.56±3.67 with a mean difference of -2.11 (p-value < 0.05) which became non-significant after 15 minutes of deflation and 60 minutes postoperatively (Table4).

TABLE 4 : Showing changes in PaCO2 and EtCO2 over time
PaCO 2 : partial pressure of arterial carbon dioxide, EtCO 2 : end-tidal carbon dioxide.