Lecture 5: LMA and Other Supraglottic Devices

LMA

-minimally invasive device in the management of the airway in unconscious patients

LMA designed for use in

spontaneous ventilation

controlled ventilation no more than 20cmH2O

indications for supraglottic device

-known or unexpected difficult airway situation

-use in elective surgeries

-alternative to face mask for controlling airway

-clear airway during resucitation

LMA invented in

1981 by Dr Brain

commercial in 1988

Dr Brain wanted to

form a seal around the laryngeal not the pharyngeal perimeter

today LMAs are used in

more than 200 million patients

structure of LMA

airway tube

mask

inflation line

standard connector on LMA

15 mm

LMA made of

medical grade silicone (reusable) or PVC (single use)

LMA curve is

30 degrees

flexible vertical bars at entry of LMA are for

preventing obstruction by the epiglottis

black line on LMA

orients the tube to midline

should face you when placing

where does the tip of LMA

upper esophageal sphincter

where does the sides of LMA

face into pyriform fossae

where does the upper borders of LMA

face base of tongue

classic LMA

reusable device

max 40 times

LMA unique

single use

shaped similar to classic

LMA supreme

seperate conduit to allow passage of a gastric tube

LMA supreme provides

improved seal around glottis

built in bite block

LMA supreme specifically designed for

positive pressure ventilation

up to 30cmH2O

LMA ProSeal

easier to plae and fits better in oropharynx

LMA ProSeal has

built in bite block and salem sump/NG/OG tube can pass into stomach

LMA ProSeal allows for

ventilation at higher pressures due to the better seal

it protects the lungs from aspiration risk and stomach from gastric inflation

what LMA allow for higher pressure ventilation

LMA ProSeal

LMA Supreme

LMA Protector

which LMA can you suction through

proseal

supreme

protector

what LMA have built in bite block

protector

proseal

supreme igel

LMA Protector

similar to LMA supreme

higher PPV threshold, gastric tube, bite block

LMA Protector tends to have

less of sore throat

can use LMA Protector for

intubating conduit since there is no epiglottic bars

what indicates cuff presure on LMA Protector

pilot cuff color code

Flexible LMA

wire reinforced flexible airway tube

allows tibe to be bent without dislodgment of LMA

Flexible LMA offers

better protection from blood and secretions that happen above the trachea

Flexible LMA does not offer

resistance to occulusion by biting

LMA Fastrach (“iLMA”)

designed for one hand use to facilitate blind intubation of the trachea

special insertion technique

LMA Fastrach is not designed for

routine cases

causes increased pressure to pharynx if used long term

contraindications of LMA/SGD device

patients who are high risk of aspiration

patient swho have low pulmonary compliance

patients unable to answer medical history

high risk of aspiration

not NPO

>14 weeks preganant

sustained multiple or massive injury

acute abdominal or thracic injury

delayed gastric emptying

opiate use before fasting

aspiration and LMAs

does NOT prevent aspiration

prevelance of aspiration under GA

1-6 in 10,000 cases

prevelance of aspiration in LMAs

2 in 10,000 cases

why not use LMA in patients who have low pulmonary compliance

the peak airway pressures needed would exceed the allotted pressure for LMA

size 1 LMA

<5kg

cuff volume 4ml

size 1.5 LMA

5-10 kg

cuff volume 7ml

size 2 LMA

10-20 kg

cuff volume 10ml

size 2.5 LMA

20-30 kg

cuff volume 14ml

size 3 LMA

30-50kg

cuff volume 20ml

size 4 LMA

50-70kg

cuff volume 30ml

Size 5 LMA

70-100 kg

cuff volume 40ml

Size 6 LMA

>100kg

cuff volume 50ml

preparing for LMA insertion

cuff should be deflated so it forms a smooth wedge shape without wrinkles and lubricate posterior

Inserting an LMA steps

1. hold at junction of cuff and tube like a pen

2. flatten LMA airway tip against hard palate

3. press mask against hard palate and push it down to soft palate until resistance

4. inflate cuff to obtain seal

thumb technique of inserting

use thumb to push instead of index finger

taping LMA

use similar technique as ETT

confirm placement with LMA

LMA should sit up when inflated

capnography

ability to ventilate patient manually

removal of LMA vs ETT

LMA less stimulating than endotracheal tube

removal of LMA DO NOT

suction below LMA-cufff forms seal with upper pharynx

manipulate the LMA with patient in light phase of anesthesia

Removing LMA

leave cuff inflated

patient will begin to swallow and follow commands

remove LMA and bite block

if LMA does not seal, leaks, or seat

do not keep adding air

withdraw and attempt again

LMA controversies

muscle relaxation

positioning

positive pressure ventilation

prolonged procedures

LMA and muscle relaxants

used in limited situations

aspiration risk high

when to use muscle relaxants with LMA

facilitate LMA placement

facilitate surgical access

prevent dislodgment of LMA

LMA positioning: yes!

supine

LMA positioning: no!

lateral

prone

beach chair

LMA and positive pressure ventilation

may be as effective as ETT

limit tidal volumes to 8ml/kg

limit pressure to 20cm H2O

LMA and tidal volumes

if cant reach good tidal volumes put ETT in

LMA and prolonged procedures

usually less than 3 hours

can be used in 4-8 hours

if using N2O check

cuff pressure frequently and adjust volume to prevent mucosal damage

can make the seals MASSIVE

LMA in cases longer than 3 hours

use Supreme and suction gastric contents

LMA advantages

less invasive than ETT

doesnt need muscle relaxants

less sore throat

useful in difficult airway

combitude

double lumen tube that achieves ventilation in any location

easy for inexperienced personnel

when do you use a combitude

when you can intubate and cant ventilate

blind combitube ends up

95% esophageal

sizes of combitube

37 french (4-6ft) and 41 french (>6ft)

NO PEDS

combitube proximal cuff

seals oro and nasopharynx

blue pilot balloon

85 (37) ml to 100 (41) ml air

combitube distal cuff

seals upper esophagus

white pilot balloon

10 ml air

blue tube combitube

pharyngeal lumen

white tube combitube

tracheoesophageal lumen

combitube insertion

left hand elevates right hand inserts

insert so teeth are between black guidelines

combitube ventilation

ventilate through blue lumen if BBS tip in esophagus, if not tube may be in trachea

no BBS in combitube

could be too deep and the oropharyngeal balloon is obstructing the trachea

combitube effectiveness

97-99% in hospital

lower success in C collar

how long can combitube be left in

8 hours

what pressure on combitube

up to 50cmH2O

king laryngeal tube

one pilot balloon for two cuffs

sizes of king laryngeal tube

60 ml adult

35ml for peds

based on weight and height

placement of king laryngeal tube

proximal cuff should lie in hypopharynx and distal in esophagus

will never go into trachea

protex soft seal

minimizes trauma and reduces N2O permeation

no bars so fiberoptic or ETT easier

ambu aura40 and auraonce

L shaped bend

reinforced for easy positioning

iGEL

easy to place

integrated bite block

no cuff to inflate