European Journal of Cardiovascular Medicine

In 1981 Dr.Archie Brain invented the first supraglottic devices classic LMA.[1] It is the [2-3] first generation versatile reusable airway with soft silicon inflatable cuff and aperture bars designed to prevent the blockage of airway by epiglottis.[4-5] It’s avail-ability in eight sizes from neonate to large adult facilitates smooth emergence with minimum hemodynamic response.

The latest addition to the array of supraglottic device in clinical practice is baska mask. It brings together features of LMA Proseal, LMA supreme, I-gel and SLIPA. It also features a number of unique improvements like- a self-sealing membranous cuff, a gastric reflux high flow suction clearance system, an inbuilt “tab” to increase its angulation, and a 90-degree suction elbow. [3]

The study aims to compare and analyze insertion characteristics and anatomical placement of baska LMA with classic LMA in elective surgical patients. Primarily, comparison was done in relation to success rate of insertion, ease of insertion, inser-tion time and fiberoptic visualization for correct positioning. We also assessed ef-fective airway time, oropharyngeal leak pressure, ease of removal and associated laryngopharyngeal morbidity.

Figure 1: Special features of the Baska Mask

Elective surgical patients, of age 18-80years, either sex, fulfilling the inclusion cri-teria and ready to give voluntary informed written consent, were selected during survey period. Inclusion criteria were -ASA grade 1 & 2 patients posted for elective surgery requiring general anaesthesia in supine position.

Patients at increased risk of aspiration of gastric content, BMI>30, having known tendency to nausea/vomiting or pharyngeal pathology, mouth opening less than 2.5 cm, undergoing head and neck surgeries or any surgeries in non-supine position or having history of cardiovascular diseases, metabolic and central nervous system dis-eases were excluded. A total of 130 patients were enrolled and divided into two groups randomly and each group has equal number of cases i.e.65 patients.

Permission was sought from the ethical committee for accomplishing the research work. After taking informed and written consent following parameters will be rec-orded for each patient: gender, age, height, body weight, BMI, ASA class, adequacy of neck movement, Mallampatti score, thyromental and inter-incisor/interdental dis-tance, status of dentition, type of operation. Patients’ baseline hemodynamic data was recorded after placement of routine monitors when at arrival to operating room.Observations were recorded by an independent blinded observer who was not involved in placement of supraglottic devices. The data collected from above men-tioned study would finally be analyzed using chi square-test.

Pre- use visual inspection was done to see that airway tube should not be high col-ored or have any cuts, tears, scratches or foreign particles [6]. The interior should be free from obstruction or foreign particles. Bar should be gently stroked to make cer-tain that they are not damaged and space between them is free from particulate mat-ter [7]. The connector should fit tightly into the outer end of the airway tube. Defla-tion / inflation test was done [8][9].

PREPARATION OF BASKA MASK

The integrity and function of the Baska Mask was checked by occluding the airway opening of the proximal connector end with one thumb, holding the mask head with the other hand and placing the other thumb over the airway opening of the mask to seal[10]. Pressure was applied for 5sec using a reservoir-bag squeeze to confirm the absence of leak in the

device. Size selection was based on the manufacturer’s recommendation of weight-based estimate plus clinical judgment [11]. At present, the Baska Mask is available in four sizes: size three (30 to 50 kg), size four (50 to 70 kg), size five (70 to 100 kg), and size six (over 100 kg) [12] [13].

A standard anesthesia sequence was followed. Upon arrival in theatre, the patients were connected to standard monitoring devices. Anesthesia was induced in the su-pine position with the patient's head in the neutral position, resting on a pillow about 8 cm in height. All patients were uniformly premedicated with IV midazolam 1mg, IV glycopyrrolate 0.2 mg and IV fentanyl 1.0-1.5 microgram/kg prior to induction of anaesthesia.

Induction of anesthesia was achieved using propofol 2.5 mg/kg. Anesthesia was con-sidered adequate for device insertion when the patient was unresponsive, had lost the eyelash reflex, and did not respond to anterior jaw thrust. If coughing, gagging, or body movement occurred during insertion, bolus doses of propofol 0.5 mg/ kg were given to achieve an adequate depth of anesthesia.

INSERTION PROTOCOL

BASKA MASK

The entire mask needs to be lubricated before insertion into the mouth, otherwise the bulk of the mask cuff may produce resistance as it traverses the hypopharynx. With the mouth open, the proximal, firmer part of the mask was compressed between thumb and two fingers and the mask was pushed past the front teeth towards the hard palate, avoiding the tongue. The tab was used only if required to help negotiate the palato-pharyngeal curve. When the mask was fully within the mouth, the tab was re-leased as soon as the tip of the mask passed around the curve. The mask shall then advance until resistance was encountered, at which point the tip of the mask was en-gaged into the upper end of the esophagus. At this stage, the patient's front teeth were opposite to the reinforced part of the tube into which the connectors are bonded [14].

Figure 2: Standard placement technique for Baska Mask [15]

The patency of the airway was ascertained and the Baska Mask was connected to the breathing circuit and fixed in place with adhesive tape. An initial assessment was made by gently squeezing the reservoir bag, whilst "fine tune" adjusting the device and observing the amplitude of end-tidal carbon dioxide waveforms and the presence of chest movement. The patient will be either left breathing spontaneously or venti-lated using IPPV, at the discretion of the anesthesiologist. A clear airway was de-fined as SpO2 >95%, ETCO2 <50 mmHg and tidal volumes >6 ml/kg. One of the clearance channels will be connected to the suction apparatus via the suction elbow and suction will be applied either continuously or intermittently as required. The other channel will be left open to atmosphere. If necessary, a lubricated orogastric tube (size 4: 14 Fr.; size 5 and 6: 16 Fr.) can be inserted simultaneously via one of the gastric channels into the stomach [16].

Figure 3: Standard technique for placement of classic LMA

Anesthesia was maintained using isoflurane 1-1.5% in oxygen at the end of surgery the anesthetic gas mixture was replaced with 100% oxygen to facilitate patient re-covery. The baska mask will be removed when protective reflex return to normal. A sudden increase in leakage, snoring, or other sound often signals the need for more anaesthetic agent.

First attempt and overall success rate of insertion (counted as an attempt when the supraglottic device is taken in and out of the mouth) were recorded. Ease of insertion was recorded as very easy (when assistant help was not required), easy (when jaw thrust was needed by assistant), difficult (when jaw thrust and deep rotation or sec-ond attempt was used for proper device insertion), very difficult (third attempt was needed for device insertion). Insertion time was the time between picking up the prepared mask and successful placement. The effective airway time was considered as the time between the picking up the prepared mask and obtaining successful cap-nograph. The anatomical position of the baska mask in-situ by fiberoptic evaluation through airway tube of the device was done using brimacombe scoring system based on the visualization of vocal cord and epiglottis.[17][18]

Figure 4: BRIMACOMBE SCORE

Secondary            parameters           recorded

Oropharyngeal    leak pressure (immediately following mask insertion by closing the expiratory valve of the circle system at fixed gas flow of 3l/min and noting the airway pressure maximum pressure allowed 40 cm water), Ease of removal -very easy ,easy ,difficult, very difficult), Whether following extubation the patient was having cough, blood stained device, no mucous and gastric con-tent, whether or not gastric fluid in the airway cavity, any postoperative airway morbidity, sore-throat ,dysphagia, dysphonia(graded as none, mild, moderate, severe at 2 hour in the postoperative room).

Intra-operative complications were recorded as well as any interven-tion required correcting the use of the supraglottic device.

Intra-operative complication were recorded as well as any interven-tion required correcting the use of the supraglottic device.

Table 1: Laryngopharyngeal morbidity parameter with scores

Minimum score – 0

Maximum score -9

Both the groups were comparable with respect to age, sex, and ASA grade and weight dis-tribution. There was insignificant difference in the groups in terms of supraglottic device size used as well as duration of anesthesia in minutes. First time success rate for the inser-tion of baska mask was significantly lower than that for classic LMA; 52/65 (80%) vs 62/65(95%) respectively. Also, overall success rate of insertion of baska was significantly lower than classic LMA.

Table 2: First attempt and overall success rate of LMA insertion.

No significant difference in ease of insertion of baska and classic laryngeal mask airway was observed. Insertion time and effective airway time were comparable.

TABLE-3 Distribution of cases according to fiber optic visualization for positioning (brimacombe score)

Both groups were compared according to fibroptic visualization of positioning. Both de-vices said to be midline according to anatomical midline position of patient. Epiglottis could be seen fiber-optically in both groups through membranous cuff. There were 55/65 (83%) patient in grade I and II in both groups. The result is significant at p < 0.05.

Table 4: Comparison of Oropharyngeal leak pressure.

Both groups were compared with respect to oropharyngeal leak pressure. It was significant-ly higher in baska mask (pvalue <.00001) as compared to classic LMA group. Sealing pres-sure ranges from 30-40 cm H₂O and 25 -35 cm H₂O in baska and classic LMA group respec-tively.

TABLE-5:-Incidence of blood staining

The result of difference in blood staining of both baska and classic LMA were significant (p-value<0.05)

Table 6: Comparison of ease of insertion of Baska and classic LMA

Both groups were compared with respect to ease of insertion. No significant difference in ease of insertion of baska and classic laryngeal mask airway was observed.

Table7: Distribution of cases in terms of time for insertion

Both groups were compared with respect to time for insertion and the difference was in-significant.

We found that overall success rate of insertion of Baska was significantly lower (table2) than classic LMA (p-value <0.05). These findings compare well with previous similar stud-ies.We found the first time insertion success rate of 80% in the current study was similar to the success rate of 77% in a previous study [12]. Comparing baska with single use LMA in low-risk female patients undergoing ambulatory               surgery. Probable explanation behind this observation was the large size of baska mask    cuff which creates difficulty during insertion. They also found that optimal sizing of baska mask remains unclear. We used the manufacturer’s recommendation to size the mask based on patient’s weight. Most of the patients in whom the initial insertion attempt was not successful required a different, usually larger sized baska mask to be inserted.

We found no difference in insertion time of baska and classic LMA (pvalue-0.26). However, this does not approximate the findings of previous study of V.Alexiev et al [12]. Which re-ported prolonged insertion time for baska as compare to classic LMA.The reason behind the difference in observation may be that the noninflatable structure of baska cuff cuts down the additional time for inflation of the cuff as in classic LMA while the bulky cuff offers a dif-ficulty in insertion that translates into longer time for insertion. Thus translating into almost equal time for insertion.

Next observation was that baska and classic LMA were having equal ease of insertion (p-value>0.05). In previous studies [12] the ease of insertion of baska is more difficult than clas-sic LMA. The difference in observation may be because of smaller sample size in our study and a different learning curve [19].

Under fiberoptic view anatomical placement of the both “device midline” corresponded to the “anatomical midline” position in all patients (table 3). The epiglottis could be seen fi-beroptically in all patients through membranous cuff by using Brimacombe score. In 48 pa-tients (73%) a perfect or near perfect view of the full anterior-posterior rima glottis distance (grade 1) could be obtained in baska group and in 46 patients (70%) in classic LMA group (p-value-0.94).

An important outcome of the study was that baska mask provided better seal with glottis aperture compared to the classic LMA (p-value<0.00001) (table 4). The reason may be thermolability of the membranous mask which makes it more adaptable to the shape of lar-yngeal outlet over time and hence a better seal [20]. In classic LMA seal depends on inflata-ble cuff and poses potential hazards as the cuff pressure may be either too high or too low. Overinflation may cause airway trauma while underinflation may result in airway leak and potential aspiration of gastric content. With the baska mask neither cuff deflation prior to insertion, nor cuff inflation, nor the use of a cuff pressure measurement device, or monitor-ing of cuff pressure during surgical intervention is required. Pressure generated on the ven-tilator while using baska mask reflects the airway pressure [21][22].

We found that there was no statistical difference in ease of removal of baska and classic LMA (p-value>0.09). Coughing during extubation, trauma to lips, laryngospasm at the time of extubation and at 2 hr, dysphagia at 2 hr and hoarseness at the time of extubation and at 2 hr were absent in both baska and classic LMA. However, we found an increased risk of mi-nor blood staining over baska mask cuff (table5) in comparison to classic LMA (p-value-0.03).

This Study had some limitations. Patients younger than 18 years or obese patients were ex-cluded due to non-availability of suitable sized Baska mask. We had 13 patients who were overweight (BMI 25-30) but none were obese. Anaesthesiologist involved in SGD insertion had greater experience with insertion of classic LMA than baska mask that may lead to a bias in observations.

We conclude that Baska mask provides a higher seal pressure than classic LMA. In contrast, the success rate for insertion of Baska mask was lower than that seen with classic LMA. Thus, in clinical situations where the seal with glottis aperture takes priority over success rate of first attempt of insertion, the baska mask may provide a useful alternative to classic LMA.

1. Rashid M Khan. Airway management, 2011;15:172-205.
2. Jayashree S. Laryngeal mask airway and its variants. Indian J Anaesth 2005; 49:275-80.
3. Van Zundert T, Gatt S. The Baska Mask – A new concept in self-sealing membrane cuff extraglottic airway devices using a sump and two gastric drains: A critical evaluation. J Obstet Anaesth Crit Care 2012;2:23-30.
4. Kim Eun Mi, Kim Min Soo, Koo Bon Nyeo, Rimlec Jeong, Young Sublec. Clinical efficacy of the classic LMA in elderly patients: a comparison with young adult pa-tients. Korean journal anaesthesia. 2015; 68: 568-74.
5. Jiwon An, SeoKyung Shin, Kijun Kim. LMa insertion in adults: comparison between fully deflated and partially inflated technique. Yonsei Med J. 2013;54:747-51.
6. Matta BF, Marsh DS, Nevin M. LMA: a more successful method of insertion , J Clin Anaesth. 1995;7:132-35.
7. Brima Combe J, Barry A, insertion of LMA – a prospective study of 4 technique. Anaesth intensive care. 199;21:89-92.
8. .Brain Al J. Three cases of difficult intubation overcome by laryngeal mask airway. Anaesthesia. 1985;40:353-55.
9. Keller C, Brimacombe JR, Morris R. Comparison of four methods for assessing air-way sealing pressure with laryngeal mask airway in adult patients. Br J Anaesth 1999;82:286-87.
10. Al-Rawahi Sas, Aziz H, Malik AM, Khan RM, Kaul N. a comparative analysis of BASKA mask versus proseal laryngeal mask for general anaesthesia with IPPV. Anaesth pain and intensive care. 2013:17:233-6.
11. Anil Kumar M R,Shetty S M, Marulasidappa M, Parmar P, Vyashnavi S.Baska mask-A third generation supraglottic airway device in clinical practice- A prospec-tive observational study.Indian J Clin Anaesth.2018;5:576-81.
12. Alexiev V, Salim A, Kevin LG, Laffey JG. An observational studyof the Baska® mask: a novel supraglottic airway. Anaesthesia 2012;67:640-45.
13. Chaudary UK, Mahajan SR, Mahajan M, Sharma C, Sharma M. a comparative analy-sis of the BASKA mask versus I-Gel for general anaesthesia surgical patients under-going laparoscopic cholecystectomy. Acta Med Int 2018;5:69-73.
14. Shanmugavelu G, Kanagarajan T. comparing the functional analysis of I-Gel with BASKA mask in laparoscopic surgeries: an observational study. Int J Res Med Sci 2018;6:1440-43.
15. Garg A, Lamba NS, Chandra N S, Singhal R K, Chaudary V. supraglottic airway de-vices in short gynecological procedures: a randomized clinical study comparing the BASKA mask and I-Gel device. J Family Med Prim Care 2019;8:1134-37.
16. Ebenezer Joel Kumar E, G Vijay Anand, Aldona Shaji R. a comparative study of BASKA mask vs proseal LMA in elective sterilization surgeries. IAIM, 2019.
17. Rashid Khan, Mohammed Maroof. Supraglottic airway devices. Airway manage-ment 2007; 12:122-24.
18. Figueredo E, Vivar-Diago M, Muñoz-Blanco F. Laryngo-pharyngeal complaints af-ter use of the laryngeal mask airway. CanJ Anaesth. 1999;46:220-25.
19. The European Resuscitation Council (ERC) and the American Heart Association (AHA) in collaboration with the International Liaison Committee on Resuscitation (ILCOR): International Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiac Care. An International Consensus on Science. Resuscitation 2000; 6:29-71.
20. Weiler N, Latorre F, Eberle B, Goedecke R, Heinrichs W. Respiratory mechanics, gastric insufflation pressure, and air leakage of the laryngeal mask airway. Anesth Analg 1997; 84:1025-28.
21. Brodrick PM, Webster NR and Num JF. Use of Laryngeal mask airway in spontane-ously breathing patients in variety of surgery. Anaesthesia. 1989; 72:99-101.
22. Tae-Hyung Han, J.Brimacombe Eun Tu Lee and Long Senk. Using LMA in elective caesarean section. Indian.Anaesth.2001;58:226-8.