A clinical trial to compare two types of ventilation during emergence in reducing post operative pulmonary complications in patients undergoing major abdominal surgeries

Not yet recruiting

Conditions: Other intraoperative and postprocedural complications and disorders of respiratory system, not elsewhere classified,

Registration Number: CTRI/2022/05/042740

Lead Sponsor: AIIMS New Delhi

Brief Summary: Postoperative pulmonary complications (POPC) are frequent complications following open abdominal surgery and may be associated with hospital mortality. The most important postoperative pulmonary complications are atelectasis, pneumonia, respiratory failure, and exacerbation of underlying chronic lung disease. General anaesthesia reduces functional residual capacity (FRC) in adult humans irrespective of use of mechanical ventilation and muscle relaxant. Formation of atelectasis in the dependent lung region is one of the most important causes of reduced FRC. Atelectasis causes postoperative hypoxemia and may contribute to the development of postoperative pulmonary complication as it might act as a nidus of infection.

Post operative atelectasis is one of most common pulmonary complication noted in surgical patients which increases risk of hypoxia and forms pathophysiological basis for other post op pulmonary complications.

In comparison to patients with pressure support, risk of atelectasis is high in patients with manual support due to

Ã pain induced respiratory muscle restriction

Ã respiratory muscle fatigue

Ã inadequately restored FRC

pressure support ventilation applies a fixed amount of pressure through each breath and thus augments the ones respiration and helps in preventing post op atelectasis.

CONSENT:

Informed and written consent will be taken. The patients will be well informed and explained in their own language that they are participating in a study, the procedure of the study and the chance of being assigned randomly to one group.

They will be explained in person and a written consent will be obtained from the patient. Patients will be made aware of their right to withdraw from the study at any time without any adverse effects on their clinical care.

RANDOMISATION

Randomisation will be achieved using a computer generated random number table with an allocation ratio of 1:1. Allocation concealment will be maintained using sequentially numbered sealed opaque envelopes. Envelopes will be prepared by an independent person not involved in the study. Envelope opening will contain be done just before extubation. Each envelope will contain a number which can allocate the participant to either manual group (Group M) or the pressure support group receiving fixed PEEP (Group P).

134 patients will be randomly divided into two groups of 67 each â€“ Group M and Group P based on the intervention received.

BLINDING

l Allocation of the patients in the study group will kept inside a sealed opaque envelop and it will be opened by a person who is not involved in this study before extubation trial.

l Patients will be blinded to the allocation as two groups.

l Outcome assessor will be blinded to the allocation.

l Data analyzer will be blinded to the allocation.

l The attending anesthesiologists will be unaware of the group allocation. Postoperative outcomes. will be assessed by another investigator that remains blinded to the type of intervention.

PREOPERATIVE :A detailed routine preoperative evaluation will be done one day prior as per standard practice. All selected patients will undergo a routine preanesthetic checkup. Adequate fasting will be maintained by nil per oral 8 hours for solids, 6 hours for liquids and 2 hours for clear fluids.

PRE-INDUCTION :Intravenous access will be established and standard ASA monitoring and NMB monitoring(TOF) will be attached after patients arrive at the preoperative holding area. All the patients in either of the groups will then undergo lung ultrasound. Lung ultrasound will be performed by a high frequency linear ultrasound probe (6- 13 MHz) and scoring will be based on a 0 - 3 point lung ultrasound score for 6 lung areas bilaterally. So, a total of 12 lung areas will be scanned, and maximum possible score will be 36.

**INTRO OPERATIVE PROCEDURE:**

In the operating room, standard monitoring as per American Society of Anesthesiologistsâ€™ recommendation (3- lead ECG, pulse oximetry, NIBP and NMB(TOF)) will be attached. A thoracic epidural catheter will be placed at T7- T9 intervertebral space, at after a negative test dose, 0.2% ropivacaine with 2 mcg/ ml of fentanyl will be used in boluses/infusion for intraoperative analgesia.

Patient will be induced with intravenous fentanyl 2mcg/ kg and propofol 2-3 mg/kg and tracheal intubation by appropriate size cuffed endotracheal tube will be facilitated by intravenous atracurium 0.5 mg/kg or vecuronium 0.1mg/kg or a rapid sequence intubation technique by rocuronium 1.2 mg/kg.

Anaesthesia will be maintained with isoflurane in air-oxygen (FiO2=0.5) targeting MAC of 0.8-1.0 and muscle relaxation will be achieved by intermittent boluses of intermediate acting non-depolarizing muscle relaxant to maintain TOF < 2. Intravenous fentanyl boluses will be used whenever HR/BP > 20% of baseline. Train-of four for neuromuscular blockade will be monitored in all patients and a TOF count of 2 or <2 will be targeted throughout the surgery. Intraoperative fluid protocol will be decided by the attending anaesthesiologist and amount of intraoperative fluid (crystalloid, colloid, blood and blood products) will be noted.

Volume control ventilation with a tidal volume of 6- 8 ml/kg of ideal body weight, respiratory rate of 12 beats per minute, PEEP of 5cm H2O and inspiratory to expiratory ratio of 1:2 will be used initially followed by adjustment targeting end tidal carbon dioxide (EtCO2) between 35-40 mmHg. An inspiratory pause of 10% of inspiratory time will be added during volume control ventilation in both the groups.

In both the groups the fixed PEEP is maintain during the intraoperative period. Last bolus dose of neuromuscular blocking agent will be given approximately 30 min before extubation.

At the end of surgery, inhalation agent will be discontinued, and residual neuro muscular blockade will be reversed by appropriate dosage of neostigmine and glycopyrrolate when TOF 3 or > 3 as per extubation protocol.

Extubation protocol

Group P ( Pressure support group)

At the end of surgery, inhalation agent will be discontinued ventilatory mode will be changed from volume controlled mode to pressure support ventilation. Patient will receive pressure support ventilation (Initial setting of driving pressure of 10cm H2O, RR of 10- 12 breaths/min and PEEP of 5cm H2O to achieve VT of 8 ml/kg), FIO2 of 0.5 will be maintained . The flow trigger will be set at 2l per min. If patient do not trigger then patient will be kept on previous ventilatory mode (VCV). PSV will be adjusted according to patient response to meet tidal volume of 6- 8 ml per Kg and respiratory rate of 10-16/min and it will be decreased gradually as patient restored his/her tidal volume and RR. Ventilatory support will be stopped when patient shows adequate VT >6ml/kg and RR of 10-14 / min without ventilatory support. PEEP will be maintained until extubation.

Group C ( Manual ventilation group)

At the end of surgery, inhalation agent will be discontinued ventilatory mode will be changed from volume controlled mode to manual ventilation.Patient will be allowed to breathe spontaneously and assisted with intermittent manual ventilation if needed. APL valve will be fixed at 5-10 to achieve TV of 6- 8 ml/kg. APL set at 5 and FIO2 of 0.5 will be maintained until extubation.

**In both groups extubation will be done**

â— when patient is responding to verbal commands

â— Tv >250 ml

â— RR>10 to 20/ min

â— Etco2<45

â— TOF ratio >0.9.

In the postoperative period, patients will be managed in the postoperative care unit/ high dependency unit and standard monitoring will be used. Patients will be started on oxygen therapy if SPO2 <94% with facemask of 4-6 Lt/min. Lung ultrasound will performed and scored as described above. Patient who is not extubated due to intra operative complication will be excluded from study.

**DATA COLLECTION:**

Data will be collected from the anaesthesia chart and separate proforma which are specifically made for the intraoperative and postoperative monitoring of these patients. The researcher will be blinded to the study. All documentation relating to the study will be stored in an anonymised case report file unique to each patient.

**Time points for outcome data**

Before induction of anaesthesia (T1)

Before applying Extubation protocol (T2),

After 30 min on arrival to PACU (T3) and

After 24 hrs of extubation (T4)

Respiratory mechanics data (peak airway pressure, plateau pressure, tidal volume, respiratory rate, driving pressure, mean airway pressure), actual FiO2 end tidal carbon di- oxide (EtCO2), SaO2, heart rate, mean arterial pressure will be noted at time points T2 and T3

POPC will be assessed till third postoperative day by Melbourne Group Scale

Lung ultrasound score will be noted at time point (T1-T4)

All patients will be followed till hospital discharge and duration of postoperative hospital stay will be noted.

Detailed Description: Not available

Recruitment & Eligibility

Status: Not Yet Recruiting

Sex: All

Target Recruitment: 134

Inclusion Criteria

Age >18 years ASA I to III.
Elective/Emergency major abdominal surgeries of > 2 hours duration.
Emergency abdominal surgeries which is not intubated prior to surgery.
Standardized analgesia with epidural.

Exclusion Criteria

BMI >35 kg/m2(Morbid Obesity).
Obstructive lung disease.
Underlying lung disease.
{Pneumotharx Pulmonary tuberculosis Pleural effusion.}.
Restrictive lung disease.

Study & Design

Study Type: Interventional

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
To compare Incidence of Atelectasis in pressure support group and control group during extubation and after 30 minutes of arrival to PACU.	T1(Before induction of anaesthesia) \| T2(Before applying Extubation protocol) \| T3(After 30 mins on arrival to PACU) \| T4(24 hrs of Extubation)

Secondary Outcome Measures

Name	Time	Method
post op pulmonary complications	Till third post operative day

Trial Locations

Locations (1): AIIMS, NEW DELHI.
🇮🇳
Delhi, DELHI, India
AIIMS, NEW DELHI.
🇮🇳Delhi, DELHI, India
Manesha K
Principal investigator
9597151262
maneshamahesh21@gmail.com