Dr majidinejad We describe basic airway skills, including opening the airway, O2 therapy, BMV, and extraglottic airway (EGA) devices.

BASIC AIRWAY MANAGEMENT AND DECISION

MAKINGDr majidinejad

We describe basic airway skills, including

opening the airway, O2 therapy, BMV, and extraglottic airway (EGA) devices

OPENING THE AIRWAY Upper airway obstruction most

commonly occurs when patients are unconscious or sedated

In these situations, tongue moves pos- teriorly into the upper airway when the

patient is in supine position

MANUAL AIRWAY MANEUVERS but research in patients with

obstructive sleep apnea using CPAP supports the concept that the airway collapses like a fexible tube

It is widely accepted that the jaw-thrust-only (without head tilt) maneuver should be performed in patients with suspected cervical spine injury, but there is no evidence that it is safer than the head-tilt/chin-lift maneuver

Importantly, the addition of CPAP may relieve airway obstruction when simple manual positioning maneuvers fail.

THE TRIPLE AIRWAY MANEUVER most common description of this

maneuver is head tilt, jaw thrust, and mouth

opening. Other authors describe the triple

maneuver differently—as a combination of upper cervical extension (head tilt), lower cervical felxion, and jaw protrusion (jaw lift)

PATIENT POSITIONING best way to position a patient’s head

and neck for opening the upper airway is “sniffng position

In normal-sized supine adults, this is accomplished by elevating the head

about 10 cm while tilting the head back

Morbidly obese patients require much more head elevation to achieve the proper sniffng position

In young children, this position is often achieved without lifting the head because the occiput of a child is relatively large

FOREIGN BODY AIRWAY OBSTRUCTION Intervention is required when the

patient is not moving air or has altered mental status.

Some patients with upper airway obstruction can be ventilated and oxygenated with aggressive high-pressure BMV, so always try this if standard BMV fails

Heimlich maneuver is most effective when a solid food bolus is obstructing the larynx

If a choking patient loses consciousness, use chest compressions in an attempt to expel the obstructing agent

After 30 seconds of chest compressions,

remove the obstructing object if you see it, attempt 2 breaths

It is important to realize that more than one technique is often required to clear obstruction

Finger sweep of the patient’s mouth only if a solid object is seen

It is recommended that suction be performed on newborns rather than giving them back blows or abdominal thrusts

in cases in which obstructive foreign bodies cannot be removed under direct visualization and aggressive ppv has failed, practitioners can try to push a subglottic foreign body beyond the carina.

SUCTIONING A large-bore dental-type suction tip is

the most effective in clearing vomitus from the upper airway because it is less likely to become obstructed by particulate matter

A large-bore dental-type tip device, such as the HI-D Big Stick suction tip, should be readily available at the bedside during all emergency airway management

Interposition of a suction trap close to the suction device prevents clogging of the

tubing with particulate debris A trap that fits directly onto a tracheal

tube has been described, and use of this device allows effective suctioning during intubation

Do not exceed 15 seconds for suctioning intervals and administer supplemental O2

before and after suctioning When feasible, perform suctioning under

direct vision or with the aid of the laryngoscope

OROPHARYNGEAL AND NASOPHARYNGEAL ARTIFCIAL AIRWAYS

Patients who are unresponsive or apneic are usually easier to ventilate with a bag-mask device when an oropharyngeal airway is in place.

In the ED, patients who tolerate an oropharyngeal airway should probably be intubated

Some clinicians use a nasopharyngeal airway to dilate the nasal passages for 20 to 30

minutes before nasotracheal intubation

The nasal airway is better tolerated by

semiconscious patients and is less likely to induce vomiting in those with an intact gag refex

OXYGEN THERAPY Resuscitate all patients in cardiac or

respiratory arrest with 100% O2. indication for supplemental O2 defned

as a PaO2 lower than 60 mm Hg or (SaO2) less than 90%.

memory loss at (PaO2) of 45 mm Hg, and loss of consciousness occurs at a PaO2 of 30 mm Hg.

Chronically hypoxemic patients can adapt and function with a PaO2 of 50 mm Hg or lower

INDICATIONS AND CONTRAINDICATIONS tissue hypoxia Shock state Respiratory distress without

documented arterial hypoxemia acute MI Administer 100% O2 to patients with

carbon monoxide poisoning

Use caution when administering supplemental O2 to hypoxic patients with (PaCO2) higher than 40 mm Hg, but do not withhold it

fear of oxygen toxicity should not prevent use of O2 when there is an indication but should encourage to use minimum concentration of O2 necessary to an spO2 ≥94%( therapeutic goals)

OXYGEN DELIVERY DEVICES High-flow delivery systems provide an

FIO2 that is relatively constant despite changes in the patient’s respiratory pattern

The Venturi mask is the high-flow delivery device that is most widely available

minimizing changes in FIO2 as the patient’s respiratory pattern changes

The mask is continuously flushed by the high flow of gas, which prevents the accumulation of exhaled gas in the mask

inspiratory flow rate for a resting adult is about 30 L/min, a rate matched by the total gas flow provided by the Venturi mask at all settings

A patient in respiratory distress may have an inspiratory flow rate of 50 to 100 L/min.

If inspiratory flow rate exceeds the total gas flow delivered by the mask, additional air will be entrained around the mask, and FIO2 will decrease

Low-flow delivery devices provide gas flow that is less than the patient’s inspiratory flow rate. The difference between the patient’s inspiratory flow and the flow delivered by the device is met by a variable amount of room air being drawn into the system

in simple mask complex interplay between mask volume, tidal volume, respiratory rate, and O2 flow determines the FIO2 delivered to the patient

A partial rebreathing mask incorporates a bag-type reservoir to increase the amount of O2 available during inspiration thereby requiring less outside air to be entrained

Nonrebreathing masks are similar to partial rebreathing masks but have a series of one-way valves

One valve lies between the mask and the reservoir and prevents exhaled gas from entering the reservoir

Two valves in the side of the mask permit

exhalation while preventing the entry of outside air

Many clinicians have the misconception

that a non-rebreathing mask can provide an FIO2 near 100%.

In practice, a non-rebreathing mask usually delivers an FIO2 of about 70%

Highflow systems should generally be used for patients who need precise control of FIO2, such as COPD patients with chronic respiratory acidosis

An oxygen flow rate of 1 to 3 L/min by nasal cannula will result in an FIO2 of 23% to 35%. Patients with signifcant hypoxemia, end-organ dysfunction, or respiratory distress require a higher FIO2 delivery system

An initial FIO2 of 24% to 28% delivered by Venturi mask is indicated for patients with hypoxemia and chronic respiratory acidosis

Equilibration of SaO2 after changes in supplemental O2 occurs within 5 min

FIO2 should be titrated to achieve therapeutic goals while minimizing the risk for complications

An SaO2 of 90% to 95% (PaO2 ≈ 60 to 80 mm Hg) is an appropriate target

In patients with COPD-associated hypercapnia, an SaO2 of 90% (PaO2 ≈ 60 mm Hg) should be the goal of O2 therapy

PREOXYGENATION FOR RAPID-SEQUENCE INTUBATION

Preoxygenation is usually accomplished by

providing the maximal FIO2 with a nonrebreather mask for 3 to 5 min before intubation

Alternatively, eight vital capacity breaths from a maximal FIO2 system, such as a nonrebreather mask or a bag-valve-mask device, is acceptable when there is no time for standard preoxygenation

The purpose of preoxygenation is not just to maximize oxygen saturation but to wash out nitrogen from the patient’s lungs and replace it with oxygen

Morbidly obese patients are best preoxygenated in a 25-degree head-up position

Sometimes patients who need preoxygenation the most are uncooperative

These patients may beneft from delayed-sequence intubation—careful to allow oxygenation with a face mask or NPPV for 2 to 3 min before administering a paralytic agent.

Ketamine (1 to 1.5 mg/kg by slow intra-

venous push) has been suggested for this technique

Another method to delay desaturation during RSI is nasopharyngeal oxygen insuffation during apnea

Using a standard nasal cannula with a nasopharyngeal airway is simpler and would probably provide the same beneft

Also, it is important to keep the upper airway open by using a jaw thrust or artifcial airway for this technique to be most benefcial

NASAL HIGH-FLOW OXYGEN high-flow nasal oxygen is a relatively

new concept that may have some utility for optimizing oxygenation in critically ill children and adults

BAG-MASK VENTILATION Many authors note that BMV is relatively

contraindicated in patients with a full stomach, those in cardiac arrest, and those undergoing RSI

goal is to achieve adequate gas exchange while keeping peak airway pressure low

the best method of BMV is to provide a tidal volume of about 500 mL delivered over a period of 1 to 1.5 seconds

Generally, wellfitting intact dentures should be left in place to help ensure a better seal with the mask

it is important to remember to use oropharyngeal or nasopharyngeal airways (or both) whenever face mask ventilation is diffcult

All bag-mask devices should be attached to a supplemental O2 source (with a flow rate of 15 L/min) to avoid hypoxia

A 2500-mL bag reservoir and a demand valve are preferred for O2 supplementation during BMV

A recent study showed that most patients with diffcult BMV became easier to ventilate after paralytic agents were administered and none were more diffcult to ventilate after paralytics

Applying Sellick’s maneuver during BMV may further decrease the risk for gastric infation and is still recommended by most airway experts.

It should be noted that the routine use of cricoid pressure during BMV of patients in cardiac arrest is not recommended in the 2010 American Heart Association Guideline

It is recommended that cricoid pressure be released immediately if there is any diffculty ventilating with a face mask in an emergency setting

EXTRAGLOTTIC AIRWAY DEVICES EGAs can be divided into two groups,

LMAs and retroglottic devices

LMAS intubating LMA (ILMA) or a

nonintubating LMA can be inserted in less than 30

seconds and provide effective ventilation in more than 98% of patients

failure to ventilate and oxygenate with the LMA occurs in about 6% of cases

Another 6% of patients with diffcult airways suffer episodes of hypoxia during attempts to intubate through the LMA.

There is evidence that ILMA performs better in cannot-intubate/cannot-ventilate situation.

Failure to ventilate with the ILMA occurs in only about 2% of cases, and hypoxia after ILMA placement is very rare

almost all patients can be adequately ventilated with the ILMA and 94% to 99% can

be intubated through the device

When brisk bleeding above the glottis makes ventilation and intubation difficult, ILMA can prevent aspiration of blood and facilitate blind or fiberoptic intubation

In patients requiring urgent cricothyrotomy or percutaneous needle insertion into the trachea the ILMA can be used to counteract anterior neck pressure

In this capacity, ILMA provides

temporary ventilation and stabilizes the cervical

spine during the surgical airway procedure

ILMA is relatively contraindicated in awake patients, especially those with a full stomach

some evidence shows that ILMA causes posterior pressure on midportion of cervical spine

device is generally considered safe in patients with an unstable cervical spine injury

Incorrect ILMA size is more likely to be a problem if the device is too small

If another ILMA size is not available, external anterior neck manipulation or downward pressure may bring the glottis and ILMA cuff into proper alignment

LMA CLASSIC

best patient position for insertion of LMA is sniffng position, with neck flexed and

head extended

Sometimes adjusting the patient’s head and neck position is easier than trying to change the position of the LMA if cuff seal

sniffng position or into the chin-to-chest position

jaw -thrust or a chin-lift maneuver

anterior neck pressure to help manipulate glottis into improved contact with LMA mask

withdraw, advance, or rotate LMA cuff

completely remove

If unsuccessful, change the size of the LMA. A larger LMA

COMPLICATIONS aspiration of gastric contents and

hypoxia

there is evidence that it provides some protection from passive regurgitation and produces less gastric infation than BMV does

RETROGLOTTIC AIRWAY DEVICES

King LT has only one airway lumen and a simplifed cuff system, so both cuffs can be infated from a single port

tip of the King LT is designed to be placed in esophagus only

PLACEMENT OF THE KING LT Size 3 is yellow and designed for

patients 4 to 5 feet in height, size 4 is red and designed for patients 5 to 6 feet in height, and size 5 is purple and designed for patients taller than 6 feet

best patient position for insertion is sniffng position, but it can be placed with the head in the neutral position if necessary

Introduce tip of device into corner of mouth while rotating the tube 45 to 90 degrees so that the blue orientation line on the tube is touching corner of the mouth

As the tip passes under the base of tongue, rotate the tube back to the midline so that blue orientation line faces the ceiling

Without exerting force, advance King LT until connector is aligned with teeth

COMBITUBE AND EASYTUBE The Combitube not recommended in

patients shorter than 4 feet It is contraindicated in patients with

suspected caustic poisoning or proximal esophageal disorders

The Combitube is available in two sizes

smaller 37-Fr device for patients 4 feet to 5 feet 6 inches tall and the larger 41-Fr device for patient taller than 5 feet 6 inches

If resistance is met in the hypopharynx, remove tube and bend it between the balloons for several seconds to facilitate insertion.

After insertion, fill the pharyngeal balloon with 100 mL of air and the distal cuff with

10 to 15 mL of air

Alternatively, use a Wee-type aspirator device on the shorter (clear) lumen to confirm that the tip is in the esophagus before ventilation through the longer (blue) lumen

If there is confusion about location of Combitube tip, use capnography to ensure that correct airway tube is being ventilated

The Combitube must also be maintained in the true midline position during insertion to avoid blind pockets in supraglottic area

Our goal should be to avoid RSI in patients who cannot be ventilated with a bag-mask device and cannot be intubated by direct or video laryngoscopy.

if RSI is our usual method of intubation, we must be prepared to perform a surgical airway when laryngoscopy, BMV, and backup devices fail