Observation of ventilation effects of Igel™ Supr

Authors: Zhiqing Gu Quanying Jin Junjun Liu Lianhua Chen

Publish Date: 2016/08/04

Volume: 31, Issue: 5, Pages: 1035-1041

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Abstract

The shortcomings of laryngeal mask airway LMA™ such as upper airway obstruction and gastric distension or airway leakage may limit its application in small children The Igel™ Igel LMASupreme™ LMAS and Ambu AuraOnce™ Ambu are three improvements upon these shortcomings This study adopted respiratory dynamic monitoring to observe the ventilation parameters of the three laryngeal masks in small children A total of 105 children were randomized into Ambu n = 35 Igel n = 35 and LMAS n = 35 groups Primary outcomes included leak pressure and respiratory dynamic data Secondary outcomes included hemodynamic data and bispectral index values after induction T0 time after successful laryngeal mask insertion T1 and at three recording points every 10 min after insertion T2 T3 and T4 as well as laryngeal mask related adverse reactions The inspiratory/expiratory tidal volume per kilogram of body weight in the Ambu group was significantly different from those in the other groups P  005 while the leak pressure in the Ambu group was significantly lower P  005 At T3 and T4 the expiratory resistance values in the Ambu group were significantly lower than those in the LMAS group P  005 We have shown that the three laryngeal masks provided secure ventilation in children 6 years of age by using continuous respiratory dynamic monitoring We concluded that the Igel presented a better sealing effect and fewer adverse reactionsThe laryngeal mask airway LMA™ as one of the extraglottic devices EGD is favored in clinical anesthesia with the advantage of simple operation and less airway and cardiovascular reactions compared to tracheal intubation as well as relatively steady airway compared to other EGDs including oropharyngeal airway laryngeal tube airway and perilaryngeal airway etc The classical LMA for children is basically obtained by proportional size decreasing of the adult LMA without considering the characteristics of the anatomical structures of the pediatrics such as a relatively large glossia short neck loose temporomandibular joint and high glottis Thus it is thought to present higher risks of complications including airway leakage displacement insufficient ventilation airway obstruction as well as gastroesophageal regurgitation and aspiration 1 Therefore many anesthesiologists hesitate to use the LMA in children 6 years of age The Igel™ Igel LMASupreme™ LMAS and Ambu AuraOnce™ Ambu laryngeal masks are three improvements on the classical LMA 2 3 4 5 6 7 8 The feature of Ambu is an arch in line with the axis of the oropharynx between its airway tube and cuff which makes it difficult to displace so it has been widely used for airway management in pediatric anesthesia in China The Igel and LMAS are two types of laryngeal mask with gastroesophageal channel Compared with the inflatable cuff of the LMAS the cuff of the Igel is made by jellylike elastomer gel which makes it more plastic according to the shape of larynxContinuous airway monitoring CAM using a side stream spirometer SSS technique has been performed in real time to continuously observe respiratory dynamic parameters including the ventilation pressure capacity resistance chest–lung compliance pressure–volume loop flowvolume loop and respiratory work to facilitate a timely understanding of the mechanical state of the intraoperative lung and airway 9 The reported detection rate of abnormal ventilation using CAM was significantly higher than that without CAM use during anesthesia in the same kind of surgeries 9 10 11 Therefore this study aimed to compare the ventilation effects of Igel LMAS and Ambu by using CAM technique to verify the effectiveness and safety of applying these three laryngeal masks in the airway management of children 6 years of age under general anesthesiaA total of 105 children aged 1–6 years graded I according to American Society of Anesthesiologists ASA marking system undergoing elective hypospadias repaired surgery were included This study was approved by the ethics committee of Children’s Hospital Shanghai Jiaotong University and all parents provided written informed consent The sample size was calculated based on pilot experiments with a calculation formula n = Zα/22σ2/E2 95  confidence interval 20  tolerable error The patients were divided into the Ambu Igel and LMAS groups by sortition randomization method Inclusion criteria were as follows fullterm birth normal birth weight no heart lung liver kidney or central nervous system function abnormalities no history of gastroesophageal regurgitation and no history of upper respiratory infection within 2 weeks before the surgeryThe children took no preoperative medicine before the anesthesia and were fasted routinely before they undergo elective operation The electrocardiography noninvasive blood pressure pulse oxygen saturation SpO2 DatexOhmeda GE and bispectral index BIS Vista™ BIS Monitoring System Covidien were monitored immediately after the children were sent to the operating room The age weight height heart rate HR mean arterial pressure MAP SpO2 and BIS of each child were recorded as baseline values An intravenous catheter was inserted and Ringer’s solution was infused For the anesthesia induction the children received intravenous injections of sufentanil 02 μg/kg atropine 001 mg/kg midazolam 1 mg and propofol 3 mg/kg Meanwhile oxygen was applied through a facemask connected to a respiratory monitor DatexOhmeda Gas Exhaust ECAiOV GEAfter the eyelash reflex disappeared and the mandibular joint loosened an appropriately size laryngeal mask according to each child’s weight and age was selected and inserted by the same anesthesiologist The intracuff pressure of the laryngeal mask was monitored and adjusted to maintain a level within the green area 22–33 cm H2O on the monitor Manllinckrodt™ Hand Pressure Gauge CovidienAfter the laryngeal mask insertion the children were mechanical ventilated using the pressurecontrolled mode DatexOhmeda Aespire GE until the end of surgery The initial parameters of pressurecontrolled mode were as follows the peak inspiratory pressure PIP was set at 15 cm H2O respiratory rate was 20 breaths/min inspiratory to expiratory ratio was 12 and positive endexpiratory pressure PEEP was set at zero Meanwhile a fiberoptic bronchoscopy FOB 22 mm Olympus CLK4 examination was used to determine laryngeal mask localization by a standard score described by Brimacombe 12 Grade 4 only the glottis is visible Grade 3 both the glottis and the posterior surface of the epiglottis are visible Grade 2 both the glottis and the anterior surface of the epiglottis are visible Grade 1 the glottis is invisible and normal ventilation is possible and Grade 0 the glottis is invisible and normal ventilation is impossible Cases with a FOB score of Grade 0 or with unobvious thoracoabdominal lifting abnormal endexpiratory carbon dioxide ETCO2 concentration and flowvolume loop under the normal ventilation status after ventilator connection were identified as insertion failure for which reinsertion was required Cases with three unsuccessful laryngeal mask insertions were changed to endotracheal intubation and were excluded from the studyThe leak pressure LP test was performed after the laryngeal mask location confirmation in supine position Under the manual control ventilation mode the APL valve adjustablepressurelimiting valve in the breathing circuit of the anesthetic machine was closed and the fresh gas flow was adjusted to 3 L/min to elevate the pressure in the breathing circuit until the airway pressure was stabilized ie the LP The testing was stopped if the airway pressure exceeded 40 cm H2O while unstable while the LP was considered 40 cm H2O 13 Gastric distension was identified by the auscultation of gurgling sounds during the inspiratory phase of mechanical ventilation as well as the comparison of abdominal perimeter pre and postoperatively 14 15

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