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CLINICAL INVESTIGATION
Year : 2008  |  Volume : 52  |  Issue : 6  |  Page : 813 Table of Contents     

Use of Classic Laryngeal Mask Airway Inserted in Prone Position for Controlled Ventilation: A Feasibility Study


1 Senior Consultant, Department of Anaesthesiology and Critical Care, Indraprastha Apollo Hospital, Sarita Vihar, New Delhi 110076, India
2 P.G.Student, Department of Anaesthesiology and Critical Care, Indraprastha Apollo Hospital, Sarita Vihar, New Delhi 110076, India

Date of Acceptance18-Aug-2008
Date of Web Publication19-Mar-2010

Correspondence Address:
Vijay Kumar
Department of Anaesthesiology and Critical Care, Indraprastha Apollo Hospital, Sarita Vihar, New Delhi 110076
India
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Source of Support: None, Conflict of Interest: None


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Traditionally, general anaesthesia for surgical procedures requiring prone position consists of induction and tracheal intubation in supine position on a trolley, and then patient is turned prone on the operation table and positioned carefully. Even though this approach is familiar to most anaesthesiologists, it is time consuming and requires shift of manpower from other tasks to properly position the patient.
In the present study as an alternative to the traditional approach, classic laryngeal mask airway has been used successfully in patients who need controlled ventilation during short, moderate and even long duration surgeries in prone position. In this feasibility study involving 100 patients it was found that insertion of laryngeal mask airway in prone position, considerably simplify the management of this group of patients, without compromising the safety.

Keywords: Laryngeal mask airway, Prone position, Controlled ventilation, Elective surgery, Muscle relaxant


How to cite this article:
Kumar V, Lalitha K, Lone T. Use of Classic Laryngeal Mask Airway Inserted in Prone Position for Controlled Ventilation: A Feasibility Study. Indian J Anaesth 2008;52:813

How to cite this URL:
Kumar V, Lalitha K, Lone T. Use of Classic Laryngeal Mask Airway Inserted in Prone Position for Controlled Ventilation: A Feasibility Study. Indian J Anaesth [serial online] 2008 [cited 2019 Dec 15];52:813. Available from: http://www.ijaweb.org/text.asp?2008/52/6/813/60693


   Introduction Top


The prone position is commonly used to provide surgical access to variety of surgeries including microdiscectomy, varicose vein avulsions, excision of pilonidal sinus etc. Conventionally, the patients are an­aesthetized in the supine position on a trolley and after tracheal intubation using non-kinking reinforced endot­racheal tube, they are turned over to prone position on operation table. Even though this method is familiar to most anaesthesiologists, this is an invasive procedure that may sometimes be unnecessary for short surgical procedures and is not without its own inherent risk of intubation. Operations performed in the prone position may be potential cause of delay in surgery schedules in busy operation theaters and may necessitate a shift of manpower from other tasks to properly position the patient. This becomes especially important if patients are obese. Alternative to this technique is inducing pa­tient in prone position and inserting laryngeal mask air­way (LMA). Laryngeal mask airway is less invasive than endotracheal intubation. Also, there is less chance of peripheral nerve damage as patients can take com­fortable position themselves before induction of anaes­thesia. Previous studies have used LMA in prone posi­tion during several surgical procedures [1],[2],[3] however use of intermittent positive pressure ventilation (IPPV) and LMA has not been reported. Hence, this study was done to see how feasible was it to use classic LMA for controlled ventilation in patients whom the anaesthesia is induced and maintained in prone position.


   Methods Top


After proper approval from the hospital ethics committee and explaining to the patients this study was conducted in 100 consenting adult patients of ASA physical status I and II who required general anaesthe­sia in the prone position. All the patients were sched­uled for elective surgery in which the use of laryngeal mask airway was deemed appropriate. Patients with suspected difficult airway, poor dentition, skeletal dis­eases and history of gastro esophageal reflux were ex­cluded from the study.

After securing a venous access the patients were asked to position themselves comfortably in the prone position with the head turned laterally at a comfortable angle on a soft pillow. Pillows were put under the tho­rax and the pelvis to allow adequate movement of an­terior abdominal wall during ventilation. Both arms were abducted and extended above the patients head. All prospective pressure points were adequately protected using cotton or gel protective padding. While patient was comfortable, standard monitors were applied. [Figure 1]

Haemodynamic and ventilatory variables were continu­ously monitored during the procedure and recorded at every five minutes interval. Pre-oxygenation with oxy­gen at 6 liters per minute by a loosely applied facemask was done until SpO2 became 100% and then anaesthe­sia was induced intravenously with fentanyl 1 mcg.kg -1 and Propofol 2-3 mg.kg -1 . After loss of consciousness, facemask was applied firmly allowing manual ventila­tion of lungs with 100% oxygen [Figure 2]. Then the head was extended by operating department assistant hold­ing it with both hands and mouth opened by pulling the tip of patient's chin by anaesthetist and LMA was in­serted as shown in [Figure 3] with its cuff in deflated posi­tion. Size of LMA was selected according to the pa­tient weight and manufacturer's recommendation. The longitudinal black line present on the classic LMA was always kept facing towards the tip of patient's nose. As the LMA passed the incisors, the patient's chin was released, allowing the tongue to fall forwards, thereby opening up the posterior oropharyngeal space for the LMA. After inflation of the cuff the patient head was carefully laid to the left or right on to the soft pillow. Muscle relaxant atracurium was given only after con­firming the position of LMA by checking the adequacy of manual ventilation for no obstruction and then prop­erly fixing it to the patients face [Figure 4]. At this stage and throughout the whole perioperative period it was made sure that the longitudinal black line present on LMA was facing towards patient's nose to avoid any rotation of LMA inside mouth and consequently pro­ducing any gas leak during IPPV. All patients were mechanically ventilated and anaesthesia was maintained with nitrous oxide and isoflurane in oxygen. Morphine and atracurium supplements were administered for ad­equate pain relief and muscle relaxation. At the end of procedure muscle relaxation was reversed with neo­stigmine and glycopyrrolate mixture and patients were transferred to recovery bed in supine position. Patients had their spontaneous ventilation restored and LMA was taken out once they were awake.

All LMAs were inserted by two of the authors (Sr.Consultant grade) having experience of using LMA of more than 18 years each.

Demographic data, haemodynamic, ventilatory, anaesthetic variables and recovery characteristics were recorded. Problems encountered before induction, at induction, during the maintenance period and recovery were noted. Arterial desaturation and bradycardia re­quiring intervention were defined as pulse oximetry satu­ration less than 94% and heart rate of less than 40 beats per minute, respectively.


   Results Top


One hundred patients who underwent general anaesthesia were studied and it took nearly 2.5 years to complete the study. The average age distribution was 45.1±15.2, the youngest being 18 and the oldest 75 years. The average body weight in kilograms was 71.0±14.9, the least being 26 and maximum 103. There was a preponderance of males (71%) as compared to females (29%). ASA physical status II (54%) was in abundance to ASA physical status I (46%). The aver­age duration of surgery in minutes was 136±30.1. The details of the various surgical procedures performed are given in the [Table 1].

[Table 2] summarizes the different haemodynamic and respiratory variables recorded at different time in­tervals after induction that shows that these variables have been very stable perioperatively. There were two cases of difficulty of insertion of LMA, which were in­serted in the second attempt. In one case there oc­curred folding of LMA cuff on itself making LMA diffi­cult to be pushed inside. In the other case patient started closing the mouth just when the LMA had passed half­way inside the oral cavity. These problems were attrib­uted to inadequate depth of anaesthesia and responded to deepening of anaesthesia. A single case of malpositioning of LMA was resolved immediately by reinserting the laryngeal mask without any supplementa­tion of anaesthesia. There was one case of sore throat, which responded to adequate hydration and steam in­halation. One of the patients experienced postopera­tive vomiting in the recovery room. This was attributed to the administration of narcotics post operatively, and responded to anti-emetics. Dental trauma in one case in the form of coming out of a loose upper incisor was observed. [Table 3] summarizes the expected and ob­served complications.


   Discussion Top


Procedures requiring prone position are tradition­ally induced, paralyzed and intubated in the supine posi­tion and then turned face down. This technique has sev­eral disadvantages like additional theatre personnel and anaesthesia time required, the risk of neurological trauma to the patient's neck and peripheral nerves,[4] risk of dis­lodgment of endotracheal tube during the turning and positioning besides the associated risk of intubation such as trauma to teeth, pharynx and larynx. Alternative to this approach is asking patients to place themselves prone comfortably before anaesthesia is induced. This enables optimal positioning because patients know their most comfortable position, so the whole process is simplified, induction time is shortened and chances of any neuro­logical trauma to patient's neck or peripheral nerves is lessened. The major disadvantage of induction in prone position is that direct laryngoscopy is usually not pos­sible for tracheal intubation. However, this problem may be overcome by the use of classic laryngeal mask air­way. Laryngeal mask airway use has been shown to pro­vide an excellent airway in the adults [5] and children [6] for surgery in supine positions with either spontaneous or controlled ventilation. Rasanen (2000) recommended the use of LMA for surgeries in the lateral decubitus or the trendelenburg positions. [7] However, when prone posi­tion is needed for surgical access, some authors (Poltronieri, 1990) rule out the use of LMA for airway control. [8] Despite the advantages most anaesthesiologists do not use LMA in the prone position. In 1992 Kee WD, reported use of laryngeal mask airway in prone position for radiotherapy. [9] Mc Caughey [3] (1993) and Milligan KA [2] (1994) reported use of LMA in prone position for elective surgical procedures. Alexander Ng et al (2002) published his experiences of over 73 cases, allowed to breathe spontaneously without significant complications. [1] However, these studies were done on spontaneously breathing patients, which has one major disadvantage and that is that of hypoventilation which is mainly due to the respiratory depression effects of inha­lational agents and opiates. In various published reports LMA has been used for airway rescue following acci­dental extubation in patients placed prone for surgery. Valero et al (2004) managed a patient in prone position with a drill bit penetrating the spinal canal at C1-C2, using a laryngeal mask. [10] Raphael et al (2004) described a case of accidental extubation of the trachea during spine surgery in a patient placed in the prone position, who was managed successfully by inserting a LMA while maintaining the patient in the same position. [11] Dingeman et al (2005) managed a five year old girl with Arnold­ Chiari malformation More Details who was accidentally tracheally ex­tubated while positioned prone during a decompressive craniotomy and cervical laminectomy using LMA with­out difficulty. [12] Brimacombe et al (2005) reported the unusual case of airway rescue in the prone position with the proseal laryngeal mask airway. [13] Recently Weksler et al (2007) published a study comparing laryngeal mask airway in prone position with conventional endotracheal tube anaesthesia and concluded that prone induction and insertion of LMA is a valid technique. [4]

In our study the feasibility of classic LMA as an alternative for providing controlled ventilation anaes­thesia in prone position was evaluated along with haemodynamic, ventilatory, and recovery characteris­tics. The undesirable side effects and problems in per­forming this technique were also looked into.

After the anaesthesia was induced, the lungs of all the patients were easily ventilated manually via a face mask. Gravity appears to help by causing the jaw and tongue to fall anteriorly. Mechanical ventilation was easily performed in all patients and sealing was adequate after using maximum cuff inflating volumes, allowing low flow technique of fresh gas flow less than a liter. Prob­ably the cephalic displacement of larynx facilitates the sealing. Once LMA position was secured and confirmed that manual controlled ventilation was possible smoothly without any obstruction then only muscle relaxant was given and ventilator switched on for controlled ventila­tion. This practice proved quite safe as no patient went into muscle relaxant induced apnoea where they could not be ventilated manually or with ventilator.

There was no significant change in systolic, dias­tolic and mean blood pressures as compared to pre­induction levels in most of the patients. However, blood pressures tend to be lower than the pre induction val­ues at the end of surgery. This can be attributed to the cardiovascular depressant effects of inhalational agent and prone positioning. There was increase of heart rate after induction in most of the patients observed. Gradu­ally heart rate stabilized at pre induction values or slightly less and heamodynamic stability was maintained throughout the procedure [Table 2]. The recovery in most of the patients was quite rapid and very smooth.

Our study confirmed the earlier published reports which demonstrated a clear advantage while providing anaesthesia after placing patients first in prone position with the use of LMA, with minor complications ame­nable to routine management. The study also confirmed the feasibility of using classic LMA in prone position using controlled ventilation without any major problems. We concluded the successful performance of controlled ventilation in these prone patients, the safety of which lies in the fact that muscle relaxants are only to be ad­ministered when laryngeal mask airway's proper posi­tion has been confirmed and secured for smooth and unobstructed manual ventilation. On the basis of our experience with this feasibility study we recommend the technique as an alternative method of airway man­agement for surgeries in prone position needing con­trolled ventilation for anaesthesiologists who will prac­tice it on a regular basis. However, randomized con­trolled trials would be needed for comparative evalua­tion of this technique with conventional endotracheal intubation and controlled ventilation.

 
   References Top

1.Ng A, Raitt DG, Smith G. Induction of anesthesia and in­sertion of a laryngeal mask airway in the prone position for minor surgery. Anesth Analg 2002; 94: 1194-1198.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]  
2.Milligan KA. Laryngeal mask in the prone position. Anaesthesia 1994; 49: 449.  Back to cited text no. 2  [PUBMED]    
3.McCaughey W, Bhanumurthy S. Laryngeal mask place­ment in the prone position. Anaesthesia 1993; 48: 1104-5.  Back to cited text no. 3  [PUBMED]    
4.Weksler N, Klein M, Rozentsveig V, Weksler D, Sidelnik C, Lottan M, Gurman GM. Laryngeal mask in prone po­sition: pure exhibitionism or a valid technique. Minerva Anestesiol 2007;73: 33-7  Back to cited text no. 4      
5.Brodrick PM, Webster NR, Nunn JF. The laryngeal mask airway. A study of 100 patients during spontaneous breathing. Anaesthesia 1989; 44: 238-241.  Back to cited text no. 5  [PUBMED]    
6.Johnston DF, Wrigley SR, Robb PJ, Jones HE. The la­ryngeal mask airway in pediatric anesthesia. Anaesthe­sia 1990; 45: 924-7.  Back to cited text no. 6      
7.Rasanen J. The laryngeal mask airway - first class on difficult airways. Finnanest 2000; 33: 302-305.  Back to cited text no. 7      
8.Poltronieri J. The laryngeal mask. Ann Fr Anesth Reanim 1990; 9: 362-366.  Back to cited text no. 8      
9.Kee WD. Laryngeal mask airway for radiotherapy in the prone position. Anaesthesia 1992; 47: 446-447.  Back to cited text no. 9  [PUBMED]    
10.Valero R, Serrano S, Adalia R, Tercero J, Blasi A, Sanchez­Etayo G, Martinez G, Caral L, Ibanez G. Anesthetic man­agement of a patient in prone position with a drill bit penetrating the spinal canal at C1-C2, using a laryngeal mask. Anesth Analg 2004 ; 98:1447-1450.  Back to cited text no. 10      
11.Raphael J, Rosenthal-Ganon T, Gozal Y. Emergency air­way management with a laryngeal mask airway in a pa­tient placed in the prone position. J Clin Anesth 2004; 16: 560-561.  Back to cited text no. 11  [PUBMED]  [FULLTEXT]  
12.Dingeman RS, Goumnerova LC, Goobie SM. The use of a laryngeal mask airway for emergent airway manage­ment in a prone child. Anesth Analg 2005; 100: 670-671.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]  
13.Brimacombe J, Keller C. An unusual case of airway res­cue in the prone position with the ProSeal laryngeal mask airway. Can J Anaesth 2005; 52: 884.  Back to cited text no. 13  [PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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