The supraglottic airway device BlockbusterTM (TuoRen Medical Instrument Co.,Ltd.,Changyuan City, China) is the recent advancement in the field of airway management devices among supraglottic devices offering advantages over other SADs. It is a second generation SAD, invented by Professor Ming Tian.1 It provides better supraglottic airway management and gastric access which reduces risk of aspiration and reduces complications during perioperative period. It allows optimal seal with average seal pressure of more than 30cm of H2O.2It also offers high haemodynamic stability. I3t’s more than 95 degree angulated short airway tube matches oropharyngeal curve which allows easy and rapid insertion. A blockbuster LMA is equipped with a blockbuster endotracheal tube which offers blind intubation through a subglottic endotracheal tube channel in case of difficult airway management. It also ensures the oxygenation and prevent hypoxemia in case of unexpected difficult airway.4

Laparoscopic Surgeries involves generation of pneumoperitoneum and positioning with head up or head down tilt with resultant cardiovascular and respiratory effects. Since Laparoscopic operations necessitates pneumoperitoneum, along with the use of nitrous oxide, oxygen and volatile anaesthetics. SAD cuff is highly permeable to nitrous oxide and carbon dioxide through cuff wall, hence both are expected to diffuse into the air filled cuff of the SAD. Thus it can be suggested that cuff volume and cuff pressure would increase during Laparoscopic Surgeries.

Laparoscopic surgeries offer the ultimate test for the efficacy of SAD use in the face of changes in intra-abdominal pressure and thoracic compliance. Several studies have been conducted to assess the efficacy of various supraglottic airway devices for maintaining the airway during general anaesthesia. 5,6There is a paucity of literature comparing the clinical performance of the Blockbuster LMA in various positions during laparoscopic surgeries involving the creation of intraperitoneal pressure during general anaesthesia. Hence, the aim of this study was to evaluate the changes in cuff pressure with Trendelenburg position and Reverse Trendelenburg position in patients undergoing laparoscopic surgeries.

The present study was conducted on 60 patients undergoing laparoscopic surgeries (Diagnostic Laparoscopy for gynaecological surgery, Laparoscopic cystectomy, Laparoscopic appendicectomy) in the Department of Anaesthesiology, Dr.R.P.G.M.C, Kangra at Tanda,

Himachal Pradesh. Patients were divided into two groups based on the position:

Group A: Trendenlenburg position (Head down 20-30 °), n= 30.

Group B: Reverse Trendenlenburg position (Head up 20-30°), n=30.

Patients (age 18yrs to 60yrs) of either sex with Body Mass Index 18.5 to 30 kg/m2,American Society Of Anaesthesiologists physical status I and II for elective laparoscopic surgery involving Trendelenburg and Reverse Trendelenburg position with an anticipated duration of 30 to 120 minutes were included in the study. Patient who were Obese (BMI >30), having any oropharyngeal disease, Limited mouth opening (inter-incisor gap < 20mm), History of low pulmonary compliance, and Patients at risk of aspiration (full stomach, previous upper gastro intestinal surgery, hiatus hernia were excluded.

All patients were instructed to remain fasting for 8 hours prior to surgery and medicated night before surgery with Tablet Alprazolam 0.25mg and Tablet Ranitidine 150mg. Intravascular fluid (Normal saline) was with 18G cannula. A multi-channel monitor showing pulse rate, electrocardiogram (ECG), oxygen saturation, non-invasive blood pressure (NIBP) was connected and baseline readings were recorded.

All patients of group A and group B were premedicated with InjGlycopyrrolate 0.2mg, Inj. Midazolam 0.02mg/kg and Inj. Fentanyl 2ug/kg i.v.Preoxygenation was done for 3 minutes and induction was done with Inj. Propofol 2mg/kg iv in slow incremental doses till the loss of verbal command and ease of mask ventilation was noted. After confirming adequate mask ventilation Inj. Atracurium 0.5mg/kg iv was administered to facilitate placement of Blockbuster TM SGA. Once the jaw relaxation was achieved, supraglottic device was inserted. Size selection of Blockbuster SGA was done according to weight of patient, SGA size 4 (weight= 50-70kg). For lubrication, water based lubricating jelly was applied on the dorsum of device. The Blockbuster LMA was placed in neutral position.

The cuff pressure and peak airway pressure were monitored:

• After placement of SGA
• Before insufflation of CO2
• After insufflation of CO2 for pneumoperitonium and intra-abdominal pressure was kept at recommended values (12-14mmHg)
• Patient was        given     Trendelenburg   position(head    down-20-30°)   /              Reverse Trendelenburg position(head up- 20-30°)
• Thereafter every 10 minutes cuff pressure and peak airway pressure were monitored until release of pneumoperitoneum (ROP),
• Till SGA was removed.

If intra-cuff pressure increased beyond the recommended level i.e. more than 60cm of H2O, its pressure was brought to baseline pressure by releasing air with the help of cuff manometer and number of times it was done was noted.EtCO2 was measured 1 min after SGA placement, thereafter every 10 minutes till the device was removed.

Haemodynamic parameters: Haemodynamics such as heart rate, systolic blood pressure, diastolic blood pressure and Mean arterial pressure, SpO2, were measured 1 min after placement of SGA, thereafter every 10 minutes till the end of surgery. After the completion of procedure, when patient regained respiratory efforts, the neuromuscular block was reversed with Inj. Neostigmine 0.05mg/kg and Inj. Glycopyrrolate 0.01mg/kg and the Blockbuster SGA was removed after deflation. Twenty four hours after the surgery, the patients were assessed for the sore throat (constant pain independent of swallowing), hoarseness of voice, dysphonia (difficulty in or pain on speaking) and numbness of tongue. The data was tabulated and subjected to statistical analysis. The level of significance adopted was 5%.

The mean age of patients in Group A was 38.33 ± 7.18 years whereas the mean age of patients in Group B was 42.37 ± 8.03 years. Group A comprised of 4 (13.3%) males and 26(86.7%) females whereas Group B comprised of 10 (33.3%) males and 20 (66.7%) females. The mean BMI of patients in Group A was found to be 23.08 ±0.96 kg/m² and mean BMI of patients in Group B was 23.22 ±1.20 kg/m². Group A comprised of 28 (93.3%) patients with ASAstatusIand2 (6.7%) patient with ASAstatusII. On the other hand, GroupBhad26cases (86.7%) with ASA status I and 4 cases (13.3%) with ASA status II. The average duration of surgeries in Group A was 70-80 mins whereas the average duration of surgeries in group B was 60 -70 mins.

The comparison between mean heart rates, SBP, DBP, MAP and SPO2 of two groups was not found to be statistically significant at any time interval(p>0.05). The comparison between meanEtCO2oftwogroupswasfoundtobestatisticallysignificantfrom10min onwardstill80 mins (p<0.05). EtCO2 showed more rise in Group A than Group B but remained within acceptable limits.

The baseline cuff pressures and peak airway pressures were comparable in Group A and Group B.

Table no.1: Comparison of cuff pressure (cmH₂O) of study participants at different intervals

The comparison between mean cuff pressure of two groups was found to be statistically significantafterCO2insufflationtillSGAremoval (p<0.05).Cuff pressure washigherin Group A than Group B.

Table no.2: Comparison of peak airway pressure (cmH2O) of study participants at different intervals

The comparison between mean peak airway pressure of two groups was found to be statistically significant after CO2 insufflationtill SGAremoval (p<0.05).Peakair way pressure were higher in Group A than Group B.

Table no.3: Comparison of Complications of study participants

 Sore throat was reported in Group A and Group B by 2 (13.3%) and 1 (3.3%) patient respectively. This was not found to be statistically significant (p=0.254). Only 1 patient reported with hoarseness in Group A and no patient reported hoarseness in Group B. This was not found to be statistically significant (p=0.333). No patient reported with dysphonia and numbness of tongue in Group A and Group B. Post-operative complications were comparatively more in Group A than Group B but not statistically significant (p>0.05).

The position of the patient in the laparoscopic surgery has an effect on cardiovascular and respiratory functions. The changes to the lithotomy, Trendelenburg, and Reverse Trendelenburg positions reduce lung compliance by altering the location of intestinal contents and diaphragm. Pneumoperitoneum created by CO2 insufflation during laparoscopic surgery elevates the diaphragm and intrathoracic pressure, which in turn also affects lung compliance.7Kiharaet al8 demonstrated that LMA insertion has no significant haemodynamic effect compared to base line, similar to our study. Ubale P et al9 conducted a study to evaluate the hemodynamic changes between endotracheal intubation and laryngeal mask airway insertion and they found that haemodynamic response consisting of an increase in Heart rate, SBP, DBP and MAP was significantly greater with ETT than that caused by LMA insertion due to release of catecholamines. EtCO2 changes were more in group A than in Group B, which could be explained by the reason that in Trendelenburg position there is cephalic displacement of diaphragm resulting from increased intra-abdominal pressure which leads to decreased lung volume, decreased functional residual capacity and hence lung compliance. The resultant enhancement of atelectasis formation leads to accumulation of CO2 in lungs due to ineffective elimination. Another cause could be redistribution of circulation which leads to decreased perfusion and hypoventilation therefore rise in EtCO2. This is in accordance with the findings of Dogru S et al.10

Similar to the study by Khadse MA et al11, it was observed that the cuff pressure increased in Trendelenburg position but not in the Reverse Trendelenburg position. This could be attributed to the conformational change of trachea by abdominal insufflation and increased peak airway pressure in group A. Increased peak airway pressure would conduct and press part of the cuff. Moreover the gravitational effect of head down tilt in Trendelenburg position could be the underlying mechanism behind elevated cuff pressure in Group A. The over all increase in cuff pressures in response to pneumoperitoneum both in Group A and Group B could be attributed to rapid diffusion of Nitrous oxide and carbon dioxide through the cuff wall which are expected to increase the cuff pressure.

Peak airway pressure were increased after CO2 insufflation till SGA removal in Group A than Group B though remained within acceptable limits. This could be explained by the change on pulmonary mechanics more in Trendenlenburg position due to increased intra-abdominal pressure as a result of pneumoperitoneum. The cephalic shift of viscera decreases diaphragmatic movement leading to increased intra-thoracic pressure which further increases lung and chest wall resistance and thereby increase in Airway resistance. Hence, increased airway resistance increases Peak Airway pressure in Trendelenburg position than Reverse Trendenlenburg position. In the study done by Kim JE et al12, they observed that ETCO2 and Peak airway pressure were increased significantly under the Trendelenburg position compared with the Reverse Trendelenburg in laparoscopic surgeries.

Park S et al13 concluded by their study that the incidences of laryngospasm, cough at removal, dysphagia or dysphonia, and hoarseness are lower with SADs as compared to endotracheal tube. Pneumoperitoneum and Trendelenburg position may increase airway pressure and cuff pressure, resulting in increased incidence of postoperative sore throat.14In Trendelenburg position there is venous congestion which leads to airway oedema, ultimately leading to higher chances of sore throat as seen in this study.

The present study highlighted the importance of position of patient on the cuff pressures while using Blockbuster Supraglottic airway device during laparoscopic surgeries. Trendelenburg or Head down position increased cuff pressure and peak airway pressure as compared to Reverse Trendelenburg position. Also, the post-operative complications were comparatively more in Trendelenburg position. Therefore, it is recommended to monitor Cuff pressure of SGA frequently in Laparoscopic surgeries. Studies with larger sample size are required to validate the findings of the study.

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