Application Of Twin-tube Laryngeal Mask Airway During Laparoscopic Surgery In The Lateral Position

ObjectiveIn many cases,Laryngeal mask airway（LMA）has replaced tracheal tube（TT）in mechanical ventilation during general anesthesia.However,up to date few studies have described its utility in laparoscopic surgeries in the lateral position.The investigators might worry about the effects of both lateral position and pneumoperitoneum on LMA ventilation.The LMAs with two tubes offer a higher seal pressure against the larynx than the LMA Classic and have a gastric tube permitting functional separation of the gastrointestinal and respiratory tracts,thus decreasing the risk of gastric distention as well as regurgitation and aspiration.In this study,firstly we were to identify if LMA Supreme could be an alternative other than TT for airway management during general anesthesia in the laterally positioned laparoscopic surgery.secondly,we would observe and compare the effect of lateral position and pneumoperitoneum on the OLP with the LMA Proseal and the LMA Supreme,and then evaluate their ventilation efficiency.MethodsIn the first part,one hundred and twenty patients scheduled to undergo elective laparoscopic urology surgery in the lateral position were included.All of patients were randomized to either Tracheal Tube group（group T,n=60）or LMA Supreme group（group S,n=60）.After induction of anaesthesia,a tracheal tube or LMA Supreme was inserted into each patient.PetCO₂ was maintained at normal level during the operation by adjusting the ventilator parameters.Arterial blood gas analysis was performed in each patient after induction of anesthesia（T₁）,5 min after pneumoperitoneum（T₂）,60 min after pneumoperitoneum（T₃）,and before the end of surgery（T₄）.Oxygenation index（PaO₂/FiO₂）,arterial partial pressure of carbon dioxide（PaCO₂）,and PH value were recorded.The respiratory parameters including end-tidal partial pressure of carbon dioxide（PetCO₂）,minute ventilation volume（MVV）,peak airway pressure（PAP）,and the gradient between PaCO₂ and PetCO₂（Pa-etCO₂）were also recorded or calculated at each time point.The incidence of cough during recovery period,postoperative hoarseness and sore throat,and the occurrence of postoperative pulmonary complications（PPCs）were ducumented by the observers.In the second part,one hundred and eighty-six patients were randomized to either LMA Proseal group（group P,n=93）or LMA Supreme group（group S,n=93）.After induction of anesthesia,one of the devices was inserted into each patient and ventilation confirmed.Our primary outcome was the OLP assessed in both the supine position and the lateral position with or without pneumoperitoneum.MVV was increased to maintain normal PetCO₂ as far as possible during surgery.Ventilatory efficiency was scored as Class I（optimal,PetCO₂ 35-45mmHg）,Class II（suboptimal,PetCO₂ 45-55mmHg）and Class III（poor,PetCO₂ >55mmHg）.Adverse events associated with LMA such as blood staining on the mask and sore throat at 2 hours and 24 hours postoperatively were also recorded.ResultsIn the first part,Compared with the PaO₂/FiO₂ measured at T₁,the PaO₂/FiO₂ at T₃ or T₄ were significantly decreased in both groups（group T :472 ±74 mmHg,456±78 mmHg vs.505±87 mm Hg;group S:460±74 mmHg,466±80 mmHg vs.503±77 mmHg）（p<0.05）.However,there was no significant difference in PaO₂/FiO₂ between the two groups at any time point.The PaCO₂ in both groups was higher than the basal value after pneumoperitoneum,and the PaCO₂ in group S was higher than that in group T at T₃ and T₄（T₃:51.3±3.9 mmHg vs.46.3±5.7 mm Hg;T₄:48.9±7.6 mm Hg vs.43.1±8.8 mmHg）（p<0.05）.PH measured at T₃ and T₄ in both groups were significantly decreased when compared with the basal value（group T: 7.32±0.04,7.32±0.07 vs.7.40±0.04;group S: 7.30±0.04,7.31±0.05 vs.7.39±0.03）（p<0.05）,but no significant difference in PH was observed between the two groups at any time point.The variation trend of PetCO₂ was consistent with that of PaCO₂ in both groups.There was no significant change in PaetCO₂ compared either intragroup or intergroup.The MVV measured at T₃ in group T was higher than that in group S（8.5±1.4 L.min-1 vs.7.2±1.2 L.min-1）（p<0.05）,at the same time points the PAP in group T was also higher than that in group S（26.7±2.3 cmH2 O vs.23.1±2.4 cmH2O）（p<0.05）.The incidence of cough during recovery period in group T was higher than that in group S（p<0.05）,and the incidence of postoperative sore throat at 2 hours in group T was also higher than that in group S（p<0.05）.There was no significant difference in the incidence of PPCs between the two groups.In the second part,the OLP with LMA Proseal was higher when compared with LMA Supreme regardless of the position and pneumoperitoneum（supine position: 29.0±3.4 cmH2 O vs.26.1±3.3 cmH2O;lateral position: 26.1±4.2 cmH2 O vs.24.8±3.5 cmH2O;after pneumoperitoneum: 25.3±3.8 cmH2 O vs.24.0±3.5 cmH2O）（p<0.05）.Within each group,the OLP was higher in the supine position than that in the lateral position with or without pneumoperitoneum（p<0.05）.However,pneumoperitoneum did not further decrease the OLP.There was no significant difference in the number of patients in Class I/II/III for ventilation scores（group P: 83/7/2 case;group S: 76/14/2 case）（p>0.05）.The incidence of adverse events was comparable in both groups（p>0.05）.ConclusionDuring laparoscopic surgery in the lateral position,ventilation with LMA Supreme could supply similar oxygenation when compared with tracheal tube.Although the increase in MVV during pneumoperitoneum was limited in ventilation with LMA Supreme,the mild hypercarbia had no significance in clinical.Therefore,LMA Supreme might be an alternative to tracheal tube for airway management during laparoscopic surgery in lateral position.Although the LMA Proseal had a higher OLP in comparison with the LMA Supreme in the lateral position for laparoscopic surgery,both devices provided comparably adequate ventilatory efficiency.