Category Archives: Anesthesia

Learning Intubation: Head Position Effects Laryngeal View

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When first learning intubation,  a beginner often concentrates on memorizing the key laryngeal anatomy. This is important of course. If you can’t recognize the vocal cords, you will not be able to successfully intubate. However, even more important to learning intubation is understanding how the larynx relates to the other structures in the head and neck. In order to intubate you must manipulate those other structures to bring the larynx into view.

A prior post, When Learning Intubation Is Hard, described in detail some of the most common barriers to learning to intubate. Here I will concentrate on helping you see how head position effects your ability to see the larynx.

Larynx Location In The Neck

To feel your own larynx, place your hand on the front of your neck, with thumb and forefinger on either side of the firm, roughly cylindrical shape in the midline.

Illustration showing Relationships thyroid and cricoid cartilage to cricothyroid membrane

Relationships thyroid and cricoid cartilage to cricothyroid membrane

The adult larynx lies opposite the 5th, 6th cervical vertebrae, as opposed to the infant larynx that lies opposite the 2nd, 3rd and 4th. The fact that the infant larynx is higher in the neck leads to greater risk of airway obstruction and a need to slightly alter technique during pediatric intubation. A link to how to intubate the pediatric patient is located at the end of this article. Here we will concentrate on the adult.

The larynx is located in front of the esophagus in the neck. The opening to the larynx, called the glottis, and the opening to the esophagus are immediately adjacent to each other. Misidentification of the esophagus as the glottic can lead to esophageal intubation.

Illustration showing how easy it is to insert a laryngoscope blade too deeply and hide the larynx during intubation of an infant or small child

It’s very easy  to insert the laryngoscope blade too deep, as in the right picture. If too deep you will not see recognizable anatomy because you are looking down the esophagus and hiding the larynx.

 

Photo of view during laryngoscopy, on the left the esophagus is seen "tented" to appear like the larynx, on the right the larynx.

If you insert your blade too deep you will hide the larynx underneath. This action also tents the esophagus and can made it mimic the glottic opening if you are not careful.

How The Larynx Relates To Other Structures

Look at this lateral Xray  of a head in neutral position. The outline of the epiglottis, the hyoid bone, the thyroid cartilage and the cricoid cartilage are easily identified. Notice the relationship of the larynx to the esophagus. The larynx lies in front of the esophagus but the opening to the larynx (the glottis) and the esophagus are right next to each other. Accidental esophageal intubation is a risk with every intubation.

Lateral view Xray showing the distinct outlines of the parts of the larynx and their relationship to the jaw, tongue and cervical spine.

Lateral view Xray showing the distinct outlines of the parts of the larynx and their relationship to the jaw, tongue and cervical spine.

Now imagine yourself intubating this patient. what would you have to do to bring the larynx into view? How deep would you have to insert a Macintosh blade to  place the tip in the vallecula? How deep would you need to insert a Miller blade to lift the epiglottis?

Here is a CT scan of another adult patient. Notice that in this second patient the larynx is located higher in the neck.

Normal CT side view showing relationship of laryngeal structures to external anatomy

Normal CT side view showing relationship of laryngeal structures to external anatomy

Whereas the epiglottis in the first patient is low behind the tongue, this patient’s epiglottis is higher. The depth of insertion and the strategy to lift the epiglottis will change from patient to patient. Straight blades often work better in patients with a larynx higher in he neck and this may be one of those patients.

How Does Neck Position Affect The Larynx During Intubation

Let’s look at a lateral Xray of our first patient, but now with his head tilted all the way back in full extension. Patients with respiratory distress, will often tilt their heads back. You can see that this position more fully opens the airway and decreases resistance to breathing.

lateral Xray of the neck in full extension showing how the relationship of the larynx changes with respect to the rest of the neck structures. Extension without placing the patient in the sniffing position will hide the larynx behind the tongue, or a so-called anterior larynx.

Lateral Xray of the neck in full extension showing how the relationship of the larynx changes with respect to the rest of the neck structures. Extension without placing the patient in the sniffing position will hide the larynx behind the tongue, or a so-called anterior larynx.

During intubation, we need to tilt the head back to bring the axis of the oral and pharyngeal axes into alignment. But if the patient is not in a good sniffing position,  with the head moved slightly forward  in addition to being tilted, the larynx may remain hidden behind the tongue during laryngoscopy.

Let me rotate this image to show you what I mean.

Lateral neck Xray showing how extreme head extension, without the sniffing position, can make visualization of the larynx difficult.

Lateral neck Xray showing how extreme head extension, without the sniffing position, can make visualization of the larynx difficult.

You can now see how anterior that larynx would look during laryngoscopy. Pushing down on the cricoid cartilage might help rescue a difficult intubation in a situation like this, but optimal head and neck positioning from the beginning would work better.

When getting ready to intubate, always glance at the side of your patient and assess whether the head and neck are in an optimal position before you start. If it’s not optimal, try to fix it. That several seconds can save you, and your patient, potential trauma.

Head Position Also Affects Laryngeal Opening

As long as we are looking at X-rays, let’s look at our first patient with his head flexed fully forward. When the head is flexed forward, the structures in the posterior pharynx and the tongue tend to obstruct the airway. You can test this by flexing your head forward as far onto your chest as you can. It becomes much harder to take a breath.

lateral Xray showing that With the head flexed fully forward onto the chest, the airway is almost fully obstructed. Visualization of the larynx wold be impossible.

With the head flexed fully forward onto the chest, the airway is almost fully obstructed. Visualization of the larynx would be impossible.

While no one would position a patient’s head this way for intubation, it’s common for novices to place too many pillows under the head trying to obtain a good sniffing position. If the head is too high, the patient, and the intubator, will not be able to tilt the head back.  In other words, our novice intubator, trying to maximize sniffing position, sabotages himself. Again, prior to intubation take a look to the side of your patient. Try to tilt the head back (or have the patient tilt their head back).

When learning to intubate, learn the anatomical relationships, not just laryngeal anatomy.  A good intubator understands that knowledge of how those structures move in relationship to each other gives you the power to manipulate that anatomy to give you the best possible view during intubation.

Please share with your fellow students. I’ve included a list with links below to previous posts on learning intubation to help you perfect your skills. Feel free to ask questions. Let me know if there are any topics that you would find helpful.

May The Force Be with You

Christine Whitten MD, author
Anyone Can Intubate, A Step By Step Guide
and
Pediatric Airway Management, A Step By Step guide

LINKS TO PRIOR DISCUSSIONS WITH MORE DETAILS OF HOW TO INTUBATE:

 

Button to see inside or buy the book Pediatric Airway Management: A Step-by-Step Guide by Christine Whitten  Button link to see inside or buy the book Anyone Can Intubate, A Step By Step Guide to Intubation and Airway Management, 5th edition on amazon

Please click on the covers to preview my books at amazon.com

Announcing My Latest Article Has Been Published: “10 Rules for Approaching Difficult Intubation”

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I’m excited. My latest article, titled, “10 Rules for Approaching Difficult Intubation,
Always Prepare for Failure” has just been released in the journal supplement Airway Management, published by Anesthesiology News.

Managing the difficult airway is one of the most challenging, risk ridden, and downright scary clinical problems in anesthesia. The article makes the point that although we all know that a “can’t intubate, can’t ventilate” scenario can happen to anyone at anytime, many of us practice as though it will never happen to us. We must always prepare for failure. In the article, I’ve provided practical information from my 38 years of experience on how to recognize, manage, and protect our patients with challenging airways.

While there is a lot of information for the novice, there are also clinical pearls for the experienced intubator. I’m hoping you will find this information helpful to you, and to your trainees.

You can find the article on-line here, where you can also download a pdf version to share:

https://www.anesthesiologynews.com/Review-Articles/Article/08-18/10-Rules-for-Approaching-Difficult-Intubation/52456

In addition to my article, please read the others as well. This issue is full of helpful, well written submissions. I have always found Anesthesiology News to provide interesting and timely updates and well written reviews, and this issue is no exception.

May The Force Be With You

Christine E. Whitten MD. author
Anyone Can Intubate, A Step By Step Guide
and
Pediatric Airway Management, A Step By Step guide

Button to see inside or buy the book Pediatric Airway Management: A Step-by-Step Guide by Christine Whitten     Button link to see inside or buy the book Anyone Can Intubate, A Step By Step Guide to Intubation and Airway Management, 5th edition on amazon

Please preview my books at amazon.com by clicking on the covers.

 

Bilateral Tension Pneumothorax: Harder To Diagnose

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Tension pneumothorax is a life-threatening emergency. We all know the signs of tension pneumothorax:

  • unilateral breath sounds (breath sounds absent on affected side),
  • thorax may be hyperresonant,
  • jugular venous distention,
  • tracheal deviation to the opposite side,
  • maximum heart sounds shifted to the opposite side, and often
  • tachycardia
  • hypotension

However diagnosis is more difficult if the patient is suffering from bilateral tension pneumothoraces. We think about bilateral tension pneumothorax occurring with trauma cases. Yet the three cases I’ve seen in my career were complications of intubation and emergency airway management.

Case 1

The 14 month old in Kenya during a volunteer medical trip was scheduled to have his cleft lip repaired as one of the last cases of the day. We had already done 10 children in that OR and the case was starting at about 9 pm. The hospital was poor and this was 1986. The only monitors we had were blood pressure, pulse, and a small, portable, one lead EKG. We did not have pulse oximetry or end-tidal CO2 available in the hospital.

I was working with a Kenyan anesthetic assistant, similar to an OR tech. I induced the child, started the IV and intubated without difficulty. At that point I turned my back to the patient. My assistant pushed the flush button on the anesthesia machine to rapidly refill the ventilation bag. What I didn’t know was that the anesthesia machine, a type I had never seen before, had a flush button that you could rotate and lock in the on position, producing continuous 30 liter per minute flow. When my assistant hit the button from an angle, he accidentally locked it on.

The next thing I heard was a loud hissing sound and when I looked down the ventilation bag was hugely distended. I quickly disconnected the circuit, turned off the flush, and checked the patient. Everything appeared fine. Good bilateral breath sounds, good heart tones, good blood pressure. I breathed a sigh of relief and we started surgery.

Starting about forty minutes into the case, I noticed that the child was more tachycardic than I expected, in the 120s. Giving a fluid bolus didn’t correct this. I was assisting his spontaneous ventilation but he seemed to be breathing shallowly and more and more quickly at about 40 breaths per minute, despite being deeply anesthetized. I was feeling uneasy but the blood pressure was fine and bilateral breath sounds were equal, although faint. The child’s dark black skin and the dim lighting in the room did not show any discernible cyanosis.

Sixty minutes into the case the child arrested, developing pulseless electrical activity. We started CPR. Breath sounds were equal, but terribly wheezy and very faint. Lung compliance was poor. Remembering the circuit over-pressurization at the beginning of the case, I worried about bilateral tension pneumothoraces. We needled both chest cavities and released a huge amount of free air from both. The pulse came back and the child stabilized. We then placed formal chest tubes.

Case 2

During a difficult intubation in the ICU, one of my colleagues inserted a bougie to assist with passage of the endotracheal tube. As he slowly advanced the tube over the bougie, one of the nurses assisting us suddenly pushed the bougie in deeper in an attempt to help. Unfortunately the tip of the bougie was pushed deep enough to penetrate the carina. Both lungs instantly collapsed and the patient went into cardiogenic shock. Emergent placement of Thora-Vents into both chest cavities quickly improved blood pressure and stabilized the patient. To read a discussion of the complications of using bougie, and how to safely avoid trachea trauma click here.

Case 3

A patient with a tracheostomy arrived in the emergency department with respiratory failure and developed ventricular tachycardia. During CPR and defibrillation, the tracheostomy tube was dislodged and then replaced. After defibrillation, VTach was converted to sinus tachycardia, but the patient then developed pulseless electrical activity. Unfortunately, during replacement of the tracheostomy tube during chest compressions, the tip of the tracheostomy tube created a false passage in the posterior wall of the trachea, with air subsequently dissecting down and causing bilateral tension pneumothoraces. The emergency room physicians quickly diagnosed tension pneumothorax using the ultrasound machine. Thora-Vents were placed and the patient stabilized.

Let’s review what happens physiologically with tension pneumothorax.

Mechanics of Breathing

To inhale, the muscles between the ribs (intercostal muscles) and the diaphragm contract. Contraction of the intercostal muscles lifts the ribs upward and outward, increasing the volume of the chest cavity. As the diaphragm contracts, it moves downward, further expanding the chest cavity. When the volume of a container increases, the pressure inside goes down. A good analogy is using a syringe. When you pull the syringe plunger, the chamber inside becomes larger, the pressure inside goes down, and the fluid is drawn into the chamber. Like liquid, air is also a fluid. Chest expansion lowers the pressure inside the chest cavity, the intrathoracic pressure, below atmospheric pressure. If the airway is open, air flows into the lungs until the two pressures are again equal.

Illustration of the mechanics of breathing showing Airflow in and out of the lungs depends on changes in air pressure inside the thoracic cavity and an open airway.

Airflow in and out of the lungs depends on changes in air pressure inside the thoracic cavity and an open airway.

When we exhale, normal elastic recoil of our chest wall compresses the rib cage. The diaphragm relaxes. The chest cavity becomes smaller. When volume decreases, pressure increases. Think of pushing the plunger on our syringe inward. As intrathoracic pressure rises higher than atmospheric pressure it pushes the remaining air (minus some of its oxygen and now containing CO2) out through the unobstructed airway.

The lungs are elastic.  As the chest wall expands, air flows into and inflates the lungs like a balloon — although in this case the balloon is composed of millions of tiny balloons like a sponge. These air sacs are called alveoli. The volume of an average breath, the tidal volume, thus generated is about 8 ml/kg and can be as high as 10-15 ml/kg with maximum expansion of the chest.

Pathophysiology of Pneumothorax

Holes in the lungs or chest wall can alter the mechanics. Open pneumothorax results when a penetrating chest wound enables air to rush in and collapse the lung. Closed pneumothorax results when air leaks from a lung (or a perforated esophagus) into an intact chest cavity.

With an open pneumothorax, expansion of the chest cavity can’t effectively decrease intrathoracic pressure. Depending on the severity, the lung may only partially expand, or not expand at all.

When the chest wall expands in the presence of closed pneumothorax, air follows the path of least resistance and fills the thoracic space. The lung itself can’t expand very well because the air around it compresses it. This is expecially true with manual ventilation, when air continues to be forced into the thoracic cage around the lung despite building intrathoracic pressure. If intrathoracic pressure gets high enough, it flattens the lung, shifts the remaining chest contents, such as the heart, to the other side, and prevents blood return. This life-threatening situation is called a tension pneumothorax.

Illustration showing how increased intrathoracic pressure shifts the heart and lungs to the left in a right sided tension pneumothorax .

Right tension pneumothorax with heart and lungs shifted to the left.

chest X ray of Left tension pneumothorax, with heart and trachea shifted to the right.

Left tension pneumothorax, with heart and trachea shifted to the right.

Tension Pneumothorax

With tension pneumothorax, the intrathroacic organs are compressed to the point of failure by the increased air pressure. Respiratory failure results from inability of the affected lung to fill. However the over-pressurized air pushes the unaffected lung to the other side, compressing it so it too cannot fill.

  • breath sounds are absent on the affected side, but also very poor on the unaffected side
  • trachea deviates away from the affected side.
  • thorax on affected side may be hyperresonant

Circulatory failure results from the increased pressure inside the chest cavity obstructing blood flow leaving of the heart as well as impeding blood flow returning to the heart from outside the chest.

  • hypotension
  • jugular venous distention
  • tachycardia
  • shift of the mediastinum (with shift of the maximally heart heart sounds)
  • potential subcutaneous emphysema

Bilateral Tension Pneumothorax

Spontaneous bilateral pneumothorax is rare, estimated at 1.4-6% of pneumothoraces. They can occur with trauma, tumor, and iatrogenic causes (1).

Bilateral tension pneumothorax can be difficult to diagnose. Breath sounds are often poor, but they tend to be equally poor on both sides. The trachea and the mediastinum may not shift, as the lungs and heart are pinned and compressed midline between the two overpressurized chest cavities.

CXR showing severe compression of heart and both lungs by bilateral tension pneumothorax

CXR showing severe compression of heart and both lungs by bilateral tension pneumothorax. (https://www.radiology.vcu.edu/programs/residents/quiz/Pulm_COTW/2002%2010%2025%20cotw.htm)

To diagnose bilateral tension pneumothorax you have to have a high index of suspicion. Whenever there is deterioration in the patient’s oxygenation or ventilatory status, the chest should be re-examined and tension pneumothorax ruled out. If you don’t think about a diagnosis, you will never make the diagnosis.

Ultrasound is increasingly considered more sensitive than chest X ray in diagnosing pneumothorax. This link leads to the Sonosite video lecture on using ultrasound to diagnose pneumothorax

Treatment is immediate needle decompression by inserting a large-bore (eg, 14 or 16 gauge) needle into the 2nd intercostal space in the midclavicular line (2). Air will usually gush out. Because needle decompression causes a simple pneumothorax, tube thoracostomy should be done immediately thereafter. However, needle decompression is not without complication. Reported complications include vessel injury and hemothorax, lung laceration, and air embolism. always consider confirming with ultrasound or chest Xray if you can quickly proceed without jeopardizing the patient.

An Anesthesia Machine Risk For Barotrauma

A common denominator in the 3 cases I describe is human error. As we approach the start of the new year with a class of brand new anesthesia trainees, let me point out one potential risk for barrotrauma: over-pressurizing the anesthesia circuit of the anesthesia machine.

This rather humorous picture is an anesthesia machine inadvertently left in test mode for several minutes, with the pop-off valve set to 20 mmHg and 10 liter flow.

picture of an anesthesia machine with Ventilation bag left overinflated during a machine check, with 10 liter flow and the pop-off set at 20mmHg demonstrating barotrauma risk

Ventilation bag left overinflated during a machine check, with 10 liter flow and the pop-off set at 20mmHg demonstrating a potential risk of barotrauma following intubation.

This potential safety issue can cause pneumothorax in our anesthetized patients if we’re not careful. Technically 20 mmHg is not that high a pressure, but I think we can all agree that the ventilation bag is distended to the extent that if this was a pair of lungs, there might be serious trauma.

Anesthesia providers often turn the oxygen flows to 10 liters during induction in order to allow the bag to fill rapidly while we mask ventilate. This allows us to make and break the mask seal repeatedly as we give IV medications and adjust inhalational agent flows, yet still rapidly ventilate again. After placement of the cuffed endotracheal tube, the provider quickly reduces flows after intubation to avoid overpressurizing the circuit.

However, it is very common for me to have to remind new trainees to open their pop-off valves after intubation to avoid over-pressurization of a circuit still receiving 10 liter flow into an endotracheal tube. My experience in Kenya makes me hyper-vigilant of circuit pressure with my students. I’m hoping that by sharing this experience, I can make you hyper-vigilant as well.

May The Force Be With You

Christine Whitten MD, author of
Anyone Can Intubate, A Step By Step Guide
And
Pediatric Airway Management; A Step By Step Guide

  1. Taegum K, Bae JS, Yuk YS. Life-Threatening Simultaneous Bilateral
    Spontaneous Tension Pneumothorax. Korean J Thorac Cardiovasc Surg 2011;44:253-256
  2. Brohi, K. (London, UK, July 01, 2006)The diagnosis and management of tension pneumothorax. Retrieved from URL: http://www.trauma.org/index.php/main/article/199/

Button to see inside or buy the book Pediatric Airway Management: A Step-by-Step Guide by Christine Whitten    Button link to see inside or buy the book Anyone Can Intubate, A Step By Step Guide to Intubation and Airway Management, 5th edition on amazon

To look inside at Amazon.com click on the cover

PostObstructive Pulmonary Edema

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Patients with postobstructive pulmonary edema (or P.O.P.E.) develop sudden, unexpected and potentially life-threatening pulmonary edema after relief of airway obstruction.  It can be mild or severe. My first experience with it was in 1983.

The Case

In 1983, we didn’t have pulse oximetry, end-tidal carbon dioxide monitoring or even automated blood pressure cuffs. The patient was a healthy 6’3” tall and 250 lbs , 20 year old man. All muscle and clearly in great shape. He had just had knee surgery under general anesthesia and was on the verge of waking up.

He was coughing vigorously on the endotracheal tube. Four people held him down. My resident, fearful he night hurt himself or the team, extubated him while he was still coughing and before he was following commands. Unfortunately the patient was still in stage 2, when the airway reflexes are hyperdynamic.

Within seconds the patient went into laryngospasm, intense spasmodic closure of the vocal cords and other laryngeal muscles. There followed several minutes of struggling to re-establish an open airway. Finally the spasm broke with the use of positive pressure and the patient awoke.

However the mood in the room quickly turned from relief to concern. Our patient started to panic, claiming that he couldn’t breathe. His color was poor. He was wheezing badly, with pink frothy sputum bubbling out of his mouth. He was awake enough to communicate with us but so panicked that he started to fight the team of caregivers.

We didn’t know what had happened to put him into what appeared to be pulmonary edema but we knew that we needed to act quickly. We quickly administered an inhaler and IV aminophylline to try to break the bronchospasm but this didn’t seem to help. He was now blue and he clearly was getting confused with the hypoxia. His blood pressure was now 260/130 and his pulse was 150.

The patient’s breathing was so labored that his peripheral IVs flowed rapidly when he took a breath and stopped flowing when he exhaled. This showed how much negative pressure was generated inside his chest cavity with each breath.

We worried that if we induced unconsciousness and paralyzed this clearly hypoxic man that we might not be able to ventilate him adequately by bag-valve-mask given the intrathoracic pressures he was clearly generating to breathe. Therefore we topicalized his nose and did an awake nasal intubation. He literally seemed to suck the endotracheal tube into the trachea during inhalation. Once intubated we slowly sedated him and then gave muscle relaxation so that we could put him on the ventilator. About 15 cm of positive end expiratory pressure (PEEP) was needed to maintain his oxygenation. We transferred him to the ICU where he gradually improved. He had recovered sufficiently by the next day to extubate.

In hindsight, the most likely diagnosis was Postobstructive Pulmonary Edema — a diagnosis that really wasn’t well known back in 1983.  I have never again seen a patient who could generate such negative intrathoracic pressure changes that he could speed up the peripheral I.V. flow rate just by inhaling.

Postobstructive Pulmonary Edema Pathophysiology

Patients with post obstructive pulmonary edema (or P.O.P.E.) develop sudden, unexpected and potentially life-threatening pulmonary edema after relief of airway obstruction. P.O.P.E. Type I follows acute airway obstruction. P.O.P.E. Type II, which is much less common, develops after surgical relief of chronic upper airway obstruction, such as a obstructive hypertrophic tonsils or  tumor. The incidence has been reported as high as 1 in a 1,000 cases.

Clinical signs include tachypnea, tachycardia, rales and rhonchi. Hypoxemia can be mild, moderate or severe. Pink frothy sputum is often present in severe cases. The CXR will show diffuse interstitial and alveolar infiltrates.

Typical CXR of a patient with postobstructive pulmonary edema showing diffuse alveolar and interstitial infiltrates

Typical CXR of a patient with postobstructive pulmonary edema showing diffuse bilateral alveolar and interstitial infiltrates

P.O.P.E. Type 1

P.O.P.E. Type I occurs when forceful attempts to inhale against an obstruction create highly negative intrathoracic pressure. This negative pressure, in turn, increases venous return, decreases cardiac output and forces intravascular fluid to shift into the alveolar space. The typical P.O.P.E. patient is young, healthy, and strong.

A common case history for P.O.P.E. Type I, is the patient who goes into laryngospasm immediately following extubation, resulting in transient airway obstruction. This is what happened in our patient. The patient then complains of dyspnea and respiratory distress. Symptoms can be mild, ranging from unexplained, asymptomatic hypoxemia, to severe  —  requiring reintubation and ventilatory support. Symptoms usually begin within an hour, but have been reported as late as 6 hours later.

Other instigating factors for P.O.P.E. Type 1 include such things as:

  • Epiglottitis
  • Croup
  • Choking/foreign body
  • Edema from anaphylaxis
  • Strangulation
  • Near drowning
  • High pressure suctioning of the endotracheal tube

P.O.P.E Type 2

P.O.P.E. Type II,  is much less common. It develops after surgical relief of chronic upper airway obstruction, such as a obstructive hypertrophic tonsils or tumor. The one clear case that I’ve seen was a healthy 30 yo woman with a fairly large goiter. She had preoperative dyspnea while laying supine as well as difficulty swallowing. We extubated her awake and following commands, with no evidence of any airway obstruction..

However after extubation her oxygen saturation remained in the high 80s to low 90s. She had bilateral rales and was coughing up small amounts of pink sputum. Chest Xray showed classic signs of pulmonary edema.

The predisposition to postobstructive pulmonary edema type 2 appears to be a  chronic obstructing lesion that produces a modes amount of positive end expiratory pressure (PEEP). This increases end-expiratory lung volume. This chronic PEEP may alter membrane permeability. When the pressure is suddenly relieved, interstitial fluid is now free to move across into the alveoli.

Surgeries that may predispose to P.O.P.E. Type 2 are removal of a chronically obstructing:

  • goiter
  • airway tumor
  • hypertrophied tonsils and adenoids
  • severe sleep apnea

Diagnosis of Postobstructive Pulmonary Edema

Since symptoms can occur up to 6 hours later, this could mean that a patient could be discharged postoperatively and then return with symptoms to the emergency room or doctor’s office. You must have a high index of suspicion. I suspect that many of the unexplained cases of mild hypoxemia in the recovery room that require prolonged postoperative stays may be related to postobstructive pulmonary edema from unrecognized and short-lived airway obstruction on extubation.

You must rule out other causes of pulmonary edema including cariogenic pulmonary edema, fluid overload, anaphylaxis, shock lung, among others. However, rales, rhonchi, wheezing, and signs of pulmonary edema on Xray in an otherwise healthy patient with no cardiac risk factors is likely postobstructive pulmonary edema.

Treatment

Treatment consists of supplemental oxygen and support. Gentle diuresis with low dose furosemide may help. In severe cases, reintubation may be required plus low levels of positive end-expiratory pressure. Full and rapid recovery can be expected with appropriate management.

Prevention

Extubation must approached with the same degree of caution and preparation as intubation. patient’s should be extubated awake or anesthetized in stage 3. Never extubate in stage 2.

My teachers also recommended never extubating while the patient was actively coughing. Wait until the coughing spasm has paused. I have never read any study looking at this, but it makes sense that extubating with relaxed vocal cords rather than vocal cords tensed and forced together would be less likely to promote laryngospasm.

To read more about laryngospasm click here. 

If you have a patient who has had significant chronic obstruction then be vigilant. Consider keeping him or her for a longer observation period in the recovery area.

May The Force Be With You
Christine E. Whitten MD
author: Anyone Can Intubate: A Step by Step Guide
and
Pediatric Airway Management: A Step by Step Guide

References

Button to see inside or buy the book Pediatric Airway Management: A Step-by-Step Guide by Christine Whitten    Button link to see inside or buy the book Anyone Can Intubate, A Step By Step Guide to Intubation and Airway Management, 5th edition on amazon

Please click on the cover to see inside the book at amazon.com

Anatomic Dead Space Affects Hypoventilation

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Understanding anatomic dead space is important to recognizing subtle hypoventilation. Hypoventilation from sedation, pain medications, anesthesia in the immediate postoperative period is common. The most obvious sign is slowing of the rate of breathing. A more subtle sign is that tidal volume becomes shallower. Having a tidal volume close to, or smaller than the patient’s dead space can lead to significant hypercarbia, hypoxia, and respiratory failure. This article discusses the concept of dead space and it’s clinical use in recognizing hypoventilation and preventing hypoxia and hypercarbia. Continue reading →

GlideScope Technique For Intubation In Small Mouths

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The GlideScope Video Laryngoscope (GVL) is an extremely useful tool for managing challenging intubations, but it can be more difficult to use if your patient has a small mouth and a high arched, narrow palate. The problem: once the GlideScope is in place in a small mouth, maneuvering the endotracheal tube around it and into the posterior pharynx can be challenging. If you can pass the endotracheal tube (ETT) at all, the cuff tends to scrape against the teeth, risking rupture. However, there is a modified GlideScope technique you can use in those situations. Continue reading →

Difficult Intubation In A Newborn

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Difficult neonatal intubation can occur unexpectedly. We’re ready to perform neonatal resuscitation in the delivery room. We may be less ready to have to deal with a difficult neonatal airway at the same time. Recently I, and my colleagues, had to manage an unanticipated difficult neonatal intubation in labor and delivery.

The Case

The baby was born extremely edematous, and in respiratory distress. Although it was easy to ventilate the baby using the NeoPuff, airway swelling prevented the neonatologist  from identifying the epiglottis and vocal cords. The anatomy was too distorted. Following protocol when faced with a difficult intubation, the neonatologist called a “Code White”, an overhead page that in my hospital summons help from anesthesia, nursing, respiratory care and pharmacy to assist with either a emergency pediatric cardiac arrest or emergency intubation.

As a responding anesthesiologist, I too was unable to see landmarks during laryngoscopy. Continue reading →

NITROUS OXIDE: SHOULD WE USE IT?

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When I was training, we used nitrous oxide on just about every anesthetic. It was easy to use. It was inexpensive. It didn’t tend to effect hemodynamics so it was useful in less stable patients when combined with an opioid. It helped speed induction through the second gas effect. It was not metabolized so renal and liver insufficiency were of less concern.

However, with all of the more recent investigation into reasons for cognitive dysfunction or decline in infants and the elderly following anesthesia, a lot more is now known about the pharmacologic disadvantages of nitrous oxide (1, 2, 3). Continue reading →

Intubation During Cardiac Resuscitation

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Intubation during cardiac resuscitation is often challenging because of the circumstances surrounding the intubation. Excitement and apprehension accompany this life saving effort. If you don’t intubate often, you’re likely to be nervous. Even experienced intubators get excited in emergency situations, but we control our excitement and let the adrenaline work for us, rather than against us.

Step one, therefore, is to remain in control of your own sense of alarm. The leaders, which includes the person in control of the airway, must stay calm. If you appear panicked, the rest of your team will follow your lead.

Step two is to quickly assess the situation. Is the patient being ventilated? Ventilation takes priority over intubation. Is there suction available? Without suction you many not be able to see the glottis, and you won’t be able to manage emesis. What help do you have? The intubator almost always needs some assistance in having someone hand equipment, or assist with cricoid pressure, among other tasks. As I tell my students, intubation is a team sport.

Finally you need to assess what position the patient is in, and how can you optimize that position. The patient is often in a less than optimal position while chest compressions are in progress. You usually find the patient in one of two awkward positions: on the ground or in a bed. This article discusses techniques to better manage intubation during cardiac resuscitation, especially with the patient in an awkward position. Illustrations are copyright from Anyone Can Intubate, 5th Edition.  Continue reading →

When Learning Intubation Is Hard

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Learning to intubate is easier for some people than for others. Sometimes, no matter how knowledgeable you are about the theory of the intubation technique, the novice can still struggle to bring it all together to pass the endotracheal tube. The anatomy can be confusing. Understanding how to place the laryngoscope blade and manipulate that anatomy can be challenging. And all the while you must be ever vigilant to protect those precious front teeth, avoid hypertension and tachycardia, and breathe for the patient at regular intervals.

I believe there are 4 chief barriers that inhibit learning how to intubate:

  1. Failure to visualize how the outside anatomy links with the inside anatomy makes it hard to predict how deeply to insert the blade.
  2. A mistaken belief that placing the laryngoscope blade itself is all that is needed to align the axes of the airway and reveal the larynx.
  3. Failure to grasp the dynamic nature of the larynx, and the need to actively manipulate it during intubation.
  4. A lack of understanding that intubation is not a sequence of isolated steps, but is instead a complex dance of interacting steps, each setting the stage for the next.

This discussion is going to assume some knowledge of the basic intubation technique. If you’d like to review those basics you can find links for multiple prior in depth discussions at the end of this article. (Illustrations and animation from Anyone Can Intubate, 5th edition, C Whitten MD.) Continue reading →

Communication In A Crisis: A Case of Respiratory Depression In A Child:

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When I’m teaching communication in a crisis to my Perioperative/OR nurses, I often recount the story of what happened during one particular child’s recovery years ago. This case, involving a 2 year old child who developed respiratory depression in the recovery room, demonstrates how good communication in a crisis, including the ability to challenge an authority figure, can improve patient safety and allow collaborative teamwork in a crisis management situation. Continue reading →

Airway Emergency: Start With The Basics of Airway Management

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We have just finished another round of Critical Event Training for my hospital’s Anesthesia and OR staff. One of the scenarios we ran was how to manage a failed airway emergency: the dreaded “can’t intubate-can’t ventilate” airway emergency scenario.

As an instructor, it’s important for me to set the stage realistically. The more real the scenario, the more the providers will learn and be able to apply the information should they ever find themselves in a comparable situation. I must observe as the trainees respond to the emergency, and then help the trainees self-analyze what went well — or not so well — during the scenario. Of course, discussion of how things went during a training scenario always leads to sharing of examples from past real life scenarios. And after 37 years of practice I’ve had a lot of sharable experiences.

One past case we discussed is particularly appropriate for those students around the country who are just beginning to learn airway management because the solution rested in basic airway management techniques. This case, involving an intubation in an ICU patient that turned into a “can’t intubate/can’t ventilate” emergency demonstrates how returning to the basics of airway management can sometimes be the way to save your patient from harm. All illustrations from Anyone Can Intubate 5th Edition. Continue reading →

Close Call In Honduras With A Nosebleed

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I recently visited Honduras with a Head and Neck surgical team where we had a close call with a potential airway obstruction due to a blood clot. The case illustrates how a provider should never make assumptions, because if those assumptions are wrong, you can endanger your patient.

After a long day in the OR, while we were packing up to leave, a nurse from the ward ran in and said that one of the patient’s who had had a septoplasty that day for chronic sinusitis was bleeding. I immediately started setting up the OR again while our surgeon went over to the ward. Continue reading →

Finding PEEP In a Bottle (of Water): Thinking Outside The Box

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As you read this I am flying to Honduras with International Relief Team on a head and neck surgery medical mission. I will attempt to post mission updates from the hospital compound, pending internet connections. Participating in a medical mission to the developing world is never easy.

Medical personnel trained in a high tech environment take for granted the complex monitoring devices, multiple choices of drugs, and plentiful support peronnel which simplify our job. When medical volunteers travel to the developing world they are often unprepared for the potential hazards produced by outdated technology, unfamiliar and sometimes poorly maintained equipment, poor sanitation, limited supplies, and a malnourished, often poorly educated population.

Let me give you an example of one rather exciting case from early in my volunteer experience. Continue reading →

MacGyvering In Anesthesia

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I used to love the old TV show MacGyver, which featured an inventive hero who frequently had to improvise some clever device from ordinary objects in order to beat insurmountable odds and save the day.  The concept was so popular that the word MacGyver became a verb. Oxford Dictionaries state that to “MacGyver” is to make or repair something “in an improvised or inventive way, making use of whatever items are at hand”.

As I have traveled the developing world on medical missions I have often had to reinvent ways to do the things I take for granted in my sophisticated operating room, such as reassembling an anesthesia machine that fell apart right after intubation (see this story here) or improvising PEEP from some suction tubing and a bottle of water. (see that story here)

But being able to improvise is just as important in the settings of the more modern hospital. Continue reading →

Hair Style Can Impact Intubation

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Healing Little Heroes director dressed as Darth Vader at Ronald McDonald House, San Diego

Our Healing Little HeroesFoundation  founder dressed as Darth Vader at Ronald McDonald House, San Diego

Last weekend I spent time with the charity group Healing Little Heroes at the San Diego Rady’s Children’s Hospital, and Ronald McDonald House. The mission of Healing Little Heroes Foundation is to help pediatric patients in hospitals and outpatient settings to heal emotionally and mentally by appearing as Superheroes. My good friend, and general surgeon, Justin Wu, dressed below as Darth Vader, set up the Foundation.

On this day we arrived in full Star Wars costumes to entertain the kids and their families. I’m dressed as Queen Amidala. Which brings me to the topic of today’s conversation. Can hairstyle impact your intubation or even your anesthetic management? The answer is yes. There is no question that if Queen Amidala needed emergency intubation, that her hairstyle would get in the way. Continue reading →

Intubation With Airway Bleeding and Massive Emesis

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During intubation, any liquid in the mouth that obscures the view of larynx not only hinders visualization, it risks aspiration. We’re used to being able to rapidly suction the mouth clear or secretions, blood, or vomit and then have a clear view of the larynx. But sometimes, either because of continued profuse airway bleeding or massive emesis, fluid continues to accumulate while we’re watching. How can you manage this situation and successfully intubate? Here I describe two cases, one involving blood and the other massive emesis, that required intubation through a large puddle of fluid. I offer tips and tricks to assist you in your future emergency management. Continue reading →

Avoiding Pediatric Drug Errors

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Pediatric drug errors are unfortunately common. The literature states that medication errors occur in 5% to 27% of all pediatric medication orders, a very sobering number. Considering that many of these errors occur in the smallest, and therefore most vulnerable, of our little patients, the potential impact is especially great.

For the last 3 months, I’ve been teaching critical event training classes for our OR and Perioperative RNs, Anesthesia MDs and CRNAs, and OR techs in preparation for opening our new hospital in San Diego. Several of the scenarios involved pediatric cases. As part of that process, I’ve been reviewing with my providers ways to avoid the potentially deadly problem of pediatric drug dosing errors as well as ways to avoid them. Let’s discuss some of the ways to make pediatric medication administration safer. Continue reading →

Difference in Manual Ventilation: Self-Inflating Ventilation Bag vs. a Free Flow Inflating Bag

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Manual ventilation with a bag-valve-mask device requires a good mask seal against the face in order to generate the pressure to inflate the lungs. But it also requires knowledge of how to effectively use the ventilation device to deliver a breath. This article will discuss the differences in ventilation technique for self-inflating vs free-flow ventilation bags. Understanding those differences is important for successful manual ventilation of your patient. Continue reading →

Ventilation Perfusion Mismatch

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Alveolar gas exchange depends not only on ventilation of the alveoli but also on circulation of blood through the alveolar capillaries. In other words it depends both on ventilation and perfusion. This makes sense. You need both oxygen in the alveoli, and adequate blood flow past alveoli to pick up oxygen, other wise oxygen cannot be delivered. When the proper balance is lost between ventilated alveoli and good blood flow through the lungs, ventilation perfusion mismatch is said to exist.

The ventilation/perfusion ratio is often abbreviated V/Q. V/Q mismatch is common and often effects our patient’s ventilation and oxygenation. There are 2 types of mismatch: dead space and shunt.

Imbalance between perfusion and ventilation is called ventilation perfusion mismatch. This illustration compares shunt, the perfusion of poorly ventilated alveoli; and Physiologic dead space: the ventilation of poor perfused alveoli.

Shunt is perfusion of poorly ventilated alveoli. Physiologic dead space is ventilation of poor perfused alveoli.

This article will describe how dead space is different from shunt. It will help you understand how you can use these concepts to care for your patient. Continue reading →