This study is randomized controlled, single blinded parallel group single centre trial to study the effect of intraabdominal pressure guided positive end expiratory pressure (PEEP) on driving pressure in paediatric laparoscopic surgery.

Driving pressure increases with increased intraabdominal pressure during laparoscopic surgery. High driving pressure is associated with increased risk of post-operative pulmonary complications.  Children are more susceptible because of their anatomical and physiological differences such as the decreased FRC due to the increased compliance of their chest wall which provides reduced counterbalance to the inward elastic recoil of the lungs. Titrating intraoperative positive end expiratory pressure according to pneumoperitoneum pressure may counterbalance pneumoperitoneum related rise in driving pressure during laparoscopic surgery

We hypothesised that application of PEEP according to intraabdominal pressure guided during intraoperative period will be more effective in reducing driving pressure in children undergoing laparoscopic surgery in lateral position. To test this hypothesis, we will conduct a randomised controlled study to compare the effects of the two methods of PEEP application [fixed PEEP vs intraabdominal pressure guided PEEP] during intraoperative period on driving pressure in paediatric laparoscopic surgery.

Secondary objectives:

Peak airway pressure (PIP), Plateau pressure (Pplat) and Mean Airway Pressure (MAP)in both groups at the end of pneumoperitoneum.

 Blinding: It is single blinded study. Only patient will be blind

Randomization: Sixty pediatric patients undergoing laparoscopic abdominal surgery in lateral position will be enrolled in study after meeting inclusion criteria. They will be randomized into two groups (Group A and Group B) based on computer generated random number table containing 30 pediatric patients in each group.  Detailed study protocol will be explained to parents one day prior to surgery after meeting the inclusion criteria. Parental consent will be taken on day of surgery.

Group A: Fixed PEEP of 8cm of H₂O will be applied after intubation and same will be maintained after lung recruitment.

Group B:  Initially PEEP of 8 CmH2O will be applied after induction of anaesthesia and maintained up to five minutes after pneumoperitoneum. Five minute after pneumoperitoneum; lung will be recruited as per recruitment protocol. After lung recruitment PEEP of 8cmH20 + 50% of abdominal pressure will be applied. This PEEP will be maintained till deflation of pneumoperitoneum. 

Anaesthesia management: -All patients will undergo a detailed pre-anesthetic check-up(PAC) one day prior to the surgery as per the institute protocol. Preoperative investigations including complete hemogram, serum electrolytes and renal function test will be recorded as per standard institute protocol. All patients will be premedicated with per oral(PO) midazolam (0.02mg/Kg) 30 minutes before shifting to operation theater(OT) if there will be no intravenous(IV) cannula present and if intravenous cannula will present then IV midazolam (0.01mg/kg) will be given five minute before shifting to OT.

In the operating room, standard monitoring as per American Society of Anesthesiologists’ recommendation (3- lead ECG (or 5 lead ECG as per requirement of the patient), pulse oximetry, NIBP) will be initiated and base line vitals (Heart Rate{HR}, Systolic BP{SAP}, Diastolic BP{DAP}, Mean arterial pressure {MAP}, SpO₂ ) will be recorded

Radial artery will be cannulated with 22/24 G catheter after induction for intraoperative hemodynamic monitoring.

General anaesthesia(GA) will be induced with intravenous fentanyl 2mcg/kilogram body weight (Kg BW) and propofol 2-3 mg/ Kg BW and tracheal intubation will be facilitated by intravenous Atracurium 0.5 mg/ Kg BW. Anaesthesia will be maintained with isoflurane in air-oxygen (FiO₂ = 0.5) targeting an end tidal concentration of 0.8-1.0 of minimum alveolar concentration (MAC) and muscle relaxation will be maintained with intermittent boluses of Atracurium to maintain train of four (TOF) count 0-1. Multimodal analgesia will be used for pain management as per the discretion of the attending anaesthesiologist. Intraoperative fluid protocol will be decided by the attending anaesthesiologist and amount of intraoperative fluid (crystalloid, colloid, blood and blood products) will be noted. During intraoperative period; patient will received appropriate PONV prophylaxis (dexamethasone 0.2mg/kg and Ondansetron 0.1mg/kg)  as per age.

At the end of surgery, inhalation anaesthetic will be stopped, and residual neuromuscular blockade will be reversed by appropriate dosage of neostigmine and glycopyrrolate. The patients will be then be extubated when fully awake and clinical end points of adequate reversal of neuromuscular blockade is achieved along with a TOF ratio of 0.9.

 Intraoperative ventilation strategy: -

After intubation initially all patients will be ventilated with volume control ventilation (VCV) with tidal volume of 8 ml/ kg body weight , Respiratory Rate of 14/minute, PEEP of 8 cmH₂0, I:E ratio of 1:2, inspiratory pause of 20-30% of total inspiratory time and peak airway pressure limit of 35cmH₂0. Respiratory rate will be adjusted according to end tidal carbon dioxide(EtCO₂) value to maintain between 35-40 mmHg. If patient will not maintain EtCO2(35-40) by increasing respiratory rate till 24 per minute then tidal volume will be increased by one milliliter per kilogram (8+1 ml/Kg BW). Five minutes after pneumoperitoneum all patients will undergo lung recruitment according to set protocol after which PEEP will be applied according to group.

Lung recruitment protocol: - It will be done in four steps. In the first step ventilatory mode will be changed from volume control ventilation (VCV) to pressure control ventilation (PCV) with respiratory rate of 12/min, PEEP of 8 cmH₂O and driving pressure of 15cmH₂O ; which will be maintained for 15 seconds. In the second step PEEP will be increased to 12cmH₂O ; in third step PEEP will be increased to 16 cmH20 and in fourth step PEEP will be increased to 20CmH2O.In all steps other parameter will be unchanged and duration of ventilation will be of fifteen seconds. Hemodynamic monitoring will be continuously carried out during the recruitment manoeuvre. Recruitment will be abandoned if there is more than 30% decrease in systolic blood pressure from baseline, heart rate decreases to 60 beats per minute or less and SpO₂ decreases to 88%. After recruitment ventilation will be again changed to VCV mode. In VCV, ventilator setting will be same as before recruitment except for the PEEP which will be applied in accordance to the allotted group.

In case of intraoperative hypoxemia (Spo2 < 94%), first Fio2 will be increased by 10% at five-minute interval till fio2 100%. If still Spo2 will not improve more than 94% then tidal volume and PEEP will be increased after lung recruitment as per protocol. Any intraoperative event will be recorded

Post-operative period:

In the postoperative period, patients will be managed in the postoperative care unit and standard monitoring will be used. All patients will receive moist oxygen through face mask with target SaO₂ of more than 95%. In the PACU, one hour after the surgery, vital signs like heart rate (HR), non-invasive blood pressure (NIBP), oxygen saturation (SpO₂), and estimated delivered FiO₂ will be noted. Patient will be discharged from PACU after attaining Aldrete’s score equal to or more than 9. After discharge from PACU child will be monitored in ward. Room air oxygen saturation will be measured on post op day 1 and postop day 3. Number of patients requiring oxygen therapy to maintain SpO2>95 % till third day of postoperative period or before discharge whichever earlier will be noted.

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