Preventing Airway Emergencies

I’m in Egypt at the 35th International Conference Egyptian Anesthesia 2019. I was given the great honor of presenting my article on the 10 Rules For Approaching Difficult Intubation: Always Prepare For Failure. That article was the most read review article on the Anesthesia News site in 2018, another honor. Thank you readers. A link to that article can be found here. Please feel free to share it with your students.

I have attended many lectures at the Egyptian Conference, and the overarching emphasis on patient safety and continuously improving care is impressive.

It’s been estimated that there are at least 25 million intubations in the United States per year and 50 million worldwide. Even though the percent risk of failed airway is very small, when multiplied by large numbers of intubations the estimates of potential number of critical airway events is impressive.

During my presentation, I referred to 3 recurring themes.

  • Preparation is key
    • You can’t prevent every difficult airway situation – but you can prevent most of them
  • Your decisions, and how you make them are important
    • You can always make a bad situation worse
  • Teamwork and Communication are key
    • You cannot and should not do this alone

Let’s look at these more closely.

Preparation is Key To Avoiding Difficult Airway Situations

Patients can be difficult to intubate because of anatomy or the circumstances surrounding the intubation. For example, failed intubations are more common in emergency room settings, prehospital settings, and delivery rooms. Emergency procedures tend to have more severe outcomes than elective ones.

According to the American Society of Anesthesiologists Closed Claims review, airway complications are twice as likely to occur out of the OR. Inadequate oxygenation is 6 times as likely. This makes sense because those situations frequently are emergencies, in locations with minimal specialized airway equipment, personnel unfamiliar with your techniques, distractions, poor patient positioning, and often, poor lighting. But no matter the status of the patient and circumstances surrounding care, there are always things that can be done to optimize the situation.

Assess Your Patient

In an emergency you may not be able to perform a detailed exam, but you should perform as complete an airway exam as possible. Don’t just look at the physical characteristics without considering why those particular traits might make the intubation or the ventilation more difficult. Instead, use the criteria of why you expect difficulty to guide your planning and your actions.

Recognizing a patient with a potentially difficult airway is an opportunity that allows you to prepare ahead to have equipment, personnel, and a backup plan. It can help you decide between awake and asleep intubation, or to choose to use or not use muscle relaxants. It also can alert you to the fact that a patient may need to receive care in a different setting or with more experienced providers, if possible. It can help you prepare your team to assist you.

Take Stock of Your Resources

Intubation is a team effort. You need to have all of the right people and equipment. Sometimes that means moving a patient to a different and more optimal location, or asking for more expert help. Ask yourself the following questions:

  • What type of help do you need for this particular patient?
  • Should this patient be intubated here, or transferred to the OR or other setting?
  • Who should intubate this patient? The first attempt is often the best chance at success. For a particular patient, that may mean allowing someone with more experience to intubate.
  • What equipment do you need?
  • Do you have all the attachments?
  • Is there functioning suction?

Make sure your staff in the OR and on the ward is well trained ahead of time. If you ask for a rescue laryngeal mask airway in a can’t intubate/can’t ventilate event, you don’t want your nurse asking you what it looks like.

Use A Critical Event Check List

No one can remember everything in today’s complex medical world. Things get even worse in a crisis. It often feels as though epinephrine doubles your strength and halves your intelligence. Stress, distractions, and sometimes chaos associated with a critical event often cause highly skilled providers to forget crucial, potentially lifesaving steps and drug dosages.

Access to a critical event checklist can be lifesaving. The aviation industry has used checklists for decades. Use of such a resource in an emergency is a wise decision, not a sign of weakness.

My hospital uses the Crisis Event Checklist from Harvard, and Brigham and Woman’s Hospital.

Position Your Patient

We have all been guilt of not optimally positioning a patient for intubation only to then have difficulty visualizing the larynx. Things are worse outside of the OR where we don’t have all of the normal positioning devices.

Take any patient with an easy airway, place him on the floor in cardiac arrest, surround him with providers whom you don’t know offering help but not knowing what you need, and that intubation will be difficult.

A more detailed discussion on positioning can be found here.

Consider Awake Intubation If You Expect Difficulty

When I was training, we didn’t have video-laryngoscopy or LMAs. Awake intubation for anticipated difficult airway was routine. If any patient looked remotely difficult we would do an awake intubation.  This made us very comfortable with the technique for emergency situations.  Blind nasal intubation and fiberoptic intubation were common procedures.

Today we don’t intubate awaken nearly as often. A main reason is that video-laryngoscopy and LMAs have revolutionized our ability to manage the majority of the challenging intubations another way. It’s fair to say that awake intubation requires more advanced skills and takes more time.

However some patients need to be intubated awake, especially if there is concern about the ability to ventilate the patient. Begin the preparation early when awake intubation is a possibility. Nasal vasoconstriction and oral drying agents take at least 20 minutes to work well. Numbing the airway must be effective. Explain to the patient what to expect and what they must do to help.

How much sedation should you give? It depends on how scary your patient is. If the first 4 steps are done well, you won’t need a lot of sedation. Use sedation cautiously. Over sedation can quickly produce apnea or make your patient uncooperative.

And remember that awake intubation doesn’t just mean fiberoptic. You can perform awake intubation with:

  • Blind nasal intubation
  • Standard laryngoscopy
  • Video-laryngoscopy
  • Via intubating or standard LMA
  • Combined techniques (e.g. Fiberoptic/LMA)

Your Decisions, And How You Make Them, Are Important

Things happen quickly during an intubation, especially in an emergency setting. It’s important to avoid unforced errors.

Call For Help Early

Oxygen desaturation once it begins will cause rapid deterioration. Don’t wait until it begins to call for help, it takes time for help to arrive and equipment to be brought.

Change Plans If Something’s Not Working.

We’re all human. Once we begin a task it is a common failing to just keep repeating the same steps over and over again, expecting that eventually it will work. This is the definition of insanity. If something doesn’t work the first time, change something.

Be Aware: Time Stands Still In A Crisis.

What seems like 1 to 2 minutes can really be 10 to 15. Force yourself to keep track of the clock. Especially pay attention to the duration of apneic periods. Lack of ventilation harms patients, not the lack of an endotracheal tube.

Know When To Stop

There are many times when we can stop and wake the patient up to do an awake intubation, or to cancel surgery and bring the patient back another day when more optimal preparations can be made — and any edema or airway trauma can have a chance to resolve.

Teamwork And Communication Are Key

You cannot and should not do this alone. I teach my students that intubation is a team effort, which means it’s a coordinated effort by a small group of people with a common goal. To succeed, everyone needs to know the problem and the plan, especially when you are expecting difficulty. If your helpers don’t know the plan, then they either could fail to do what you need them to do or could even accidentally sabotage your efforts.

Function As A Team.

Anesthesiologists really good at talking to each other and not so good at keeping the team informed. Your team can’t read your mind.

Your team also needs to be empowered to give suggestions. Everyone needs to know that if they see something, they should say something.

We need the leaders in a critical event to be open to feedback and suggestions. We need to foster a clinical environment in which all of our staff feels empowered enough to speak up when they see something.

TeamSTEPPS is an educational program whose goal is to create highly functioning crisis management teams. In TeamSTEPPS, there is something called the Two-Challenge Rule for when you feel there has been a potential breach of safety. The Two-Challenge Rule states that if your first verbal observation of a problem is not acknowledged or acted upon, then you should challenge again. If the safety issue persists, then becoming more assertive is recommended. Don’t curse, but use “CUS” words, that is:

  • I am Concerned about …
  • I am Uncomfortable because …
  • This is a Safety issue …

It’s very difficult to challenge anyone in authority. The airline industry recognized this prior to initiating industry-wide retraining in teamwork and communication. There were accident reports of airplanes crashing, flying into mountains and running out of fuel, because copilots and other flight personnel did not feel empowered to point out mistakes they had recognized. The airlines realized they had a culture that showed:

  • excessive deference to a leader;
  • hesitation of subordinates to speak up; and
  • reluctance to immediately question a clearly unusual or suspect event.

If a copilot facing personal death in an airplane crash can’t question the pilot, how easy is it for a nurse, for example, to challenge a doctor?

We Have The Power To Decrease The Incidence Of Bad Outcomes

In closed claims analyses, human error has been implicated in 80% of critical events. Human error is unavoidable and therefore we need to work hard to avoid it.

We need to carefully assess, develop a strategy for Plans A, B and C and gather our resources before we start.

We need to think carefully and reassess how our plan is going as our care proceeds. You can always make a bad situation worse.

We need to improve our skills in teamwork, leadership, and communication.

Pay attention to those three principals. If we do, then we can help make errors much less likely to occur, and much less damaging when they do.

 

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

 

 

ETCO2: Valuable Vital Sign To Assess Perfusion

Like pulse oximetry before it alerting us to changes in oxygenation, end-tidal CO2 monitoring, or ETCO2, is rapidly becoming an additional vital sign. We routinely use ETCO2 to provide information on ventilation. But ETCO2 can also provide valuable information on the adequacy of cardiac perfusion. It can be an essential tool in ensuring optimal, high quality chest compressions during cardiac resuscitation.

Some Physiology

Ventilation and oxygenation are different. Ventilation exchanges air between the lungs and the atmosphere so that oxygen can be absorbed and carbon dioxide can be eliminated. Oxygenation is simply the addition of oxygen to the body. Under normal circumstances, hyperventilation with room air will lower your arterial carbon dioxide content (PaCO2) significantly, but not change your oxygen levels much at all. On the other hand, if you breathe a high concentration of oxygen without changing your respiratory rate, your arterial oxygen content (PaO2) will greatly increase. However, your PaCO2 won’t change.

Oxygenation changes PaO2. Ventilation changes PaCO2.

Some History Of Old Fashioned Monitors

When I started my anesthesia training in 1980, we monitored the patient with a manual blood pressure cuff, EKG, pulse, and temperature. Pulse oximetry and capnography were not yet in clinical use. If we wanted to determine PaO2, or PaCO2, we needed to draw a blood gas. Frequent blood gas determinations, or the need to monitor continuous perfusion pressures, often necessitated placement of an arterial line.

To provide an indirect indicator of perfusion, we used a precordial stethoscope attached to an earpiece to continuously listen to heart sounds. An attentive anesthesiologist could use changes in the loudness or crispness of the heart tones to alert him or her to changes in cardiac output. As the patient got lighter or if the blood pressure rose, heart tones got louder and sharper. Low blood pressure brought muffled, faint heart tones independent of heart rate. We were essentially using our ears in place of the plethysmograph waveform that pulse oximetry would eventually provide.

Pulse Oximetry

Pulse oximetry revolutionized anesthetic safety. Pulse oximetry was a non-invasive way of measuring oxygen saturation. Oxygen saturation  is the percent of Hemoglobin (Hgb) binding sites in the blood that are carrying oxygen. Hemoglobin is a chemical molecule in the red blood cell (RBC) that carries oxygen on specific binding sites. Each Hgb molecule, if fully saturated, can bind four oxygen molecules. Depending on conditions, Hgb releases some percentage of the oxygen molecules to the tissues when the RBC passes through the capillaries.  We can measure how many of these binding sites are combined, or saturated, with oxygen. This number, given as a percentage, is called the oxygen saturation or simply O2 Sat, commonly pronounced “Oh Two SAT”. it is also referred to as SPO2. When all the Hgb binding sites are filled, Hgb is 100% saturated.

Oxygen saturation and PaO2 are NOT equivalent, and they have significant clinical differences that you can read about here.

What’s The Difference Between Oxygen Saturation And PaO2?

However, with pulse oximetry we could now measure oxygen saturation. We could immediately see in real time if our patient was hypoxemic or hypoxic and, if so, diagnose the cause and treat it before harm was done.

Watching the quality of the waveform, along with the oxygen saturation, told us valuable information about perfusion. The higher the amplitude of the wave, the stronger the pulse was. The more damped out the waveform appeared, the weaker the pulse.

With this new tool, and with the OR environment becoming increasingly noisy, use of the precordial stethoscope has largely faded away. Pulse oximetry quickly spread to ICUs, on wards, and clinics to monitor patients at risk. Pulse oximetry has become a fifth vital sign.

I believe we are seeing the same transition with end-tidal CO2 monitoring.

END TIDAL CO2 Has Many Uses

What Is ETCO2?

Capnography refers to the process of measuring the partial pressure of end-tidal CO2 in each expired breath. Providers measure the value of ETCO2 in each exhaled breath with a very thin tube inserted into the breathing circuit or the patients oxygen mask or nasal prongs.

The waveform (capnogram) that you then see on the capnography monitor provides a real time recording of the patient’s respiratory rate, pattern and depth of breathing, and of course the value of CO2 exhaled. These measurements help the provider evaluate adequacy of ventilation.

The author looks at the capnography waveforms during an anesthetic to evaluate ETCO2 values and the adequacy of ventilation.

The author looks at the capnography waveforms during an anesthetic to evaluate end-tidal CO2 (ETCO2) values and the adequacy of ventilation.

ETCO2 Helps Assess Adequacy of Ventilation

We routinely measure ETCO2 for every patient in the operating room. We use it increasingly for conscious sedation provided in treatment rooms and on the wards. ETCO2 and PaCO2 are not the same value. PaCO2 is the concentration of CO2 in arterial blood. ETCO2 is the concentration of CO2 in the exhaled breath, and is close to alveolar CO2. ETCO2 is usually about 5 mmHg below PaCO2. This makes sense. If the concentration of CO2 in the alveoli were higher than in the blood stream, CO2 could not enter the lungs and would not be exhaled.

ETCO2 offers a valuable trending tool to monitor and control ventilation. It alerts us immediately if the patient hyperventilates, hypoventilates, or becomes apneic.

  • A normal trace appears as a series of rectangular waves in sequence, with a numeric reading (capnometry) that shows the value of exhaled CO2. “Normal” ETCO2 is in the range of 35 to 45 mmHg.
  • In hyperventilation, the CO2 waveform becomes smaller and more frequent, and the numeric reading falls below the normal range.
  • In hypoventilation), the waveform becomes taller and less frequent, and the numeric reading rises above the normal range.
  • Fattening of the waveform indicates an airway obstruction.
  • If the series of rectangular waves become a flat line, the patient is not breathing.

Use ETCO2 In The Perioperative Areas

I believe we should increase our use of ETCO2 in our perioperative areas and procedure rooms. Patients receiving conscious sedation on the ward or recovering from anesthesia are arguably at more risk of airway compromise than patients in the operation room. They are often under more intermittent observation. I encourage my recovery room nurses to use end-tidal CO2 monitoring when they are caring for patients at risk of hypovention or obstruction such as those:

  • exhibiting prolonged sedation,
  • with opioid induced respiratory depression,
  • history of sleep apnea,
  • any cardiovascular instability
  • any time they are worried about a particular patient.

For clinical examples of how ETCO2 can change during clinical care and how we can use ETCO2 to guide our treatment, read more here.

How Does Hypoventilation Cause Hypoxemia?

Anatomic Dead Space Affects Hypoventilation

Don’t Withhold Oxygen From That CO2 Retainer

ETCO2 Helps Verify Intubation

Esophageal intubation or accidental extubation are always risks.  Monitoring ETCO2 increases safety. The continued presence of CO2 in the exhaled breath can only mean placement of the tube in the trachea. Loss of the ETCO2 trace indicates extubation or disconnection from the circuit the ETCO2.

The shape of the capnography waveform can also indicate the severity of problems such as bronchospasm or other cause of increased resistance to breathing or exhalation.

ETCO2 Is An Early Sign Of Poor Perfusion or Cardiac Arrest

Oxygen delivery and carbon dioxide removal depend on three systems: lungs, blood and circulation. It’s important to remember that adequate oxygen absorption and delivery depends on the interaction between lung function and circulation. As soon as cardiac output starts to fall, blood perfusion through the lungs falls. CO2 now has more difficulty being carried to the lungs for exhalation. This leads to a rise in PaCO2 in the blood stream and a fall in ETCO2.

Oxygen delivery and CO2 removal from the lungs depend on lung function, blood hemoglobin concentration, and circulation. Disturbance in any of these risks respiratory distress or failure. If lung function and Hgb are stable, then changes in ETCO2 imply changes in perfusion.

Oxygen delivery and CO2 removal from the lungs depend on lung function, blood hemoglobin concentration, and circulation. Disturbance in any of these risks respiratory distress or failure. If lung function and Hgb are stable, then changes in ETCO2 imply changes in perfusion.

In the operating room, I often see a drop in ETCO2 even before blood pressure itself starts to fall. As long as there is some circulation, there will be some ETCO2 present, even if you can’t feel a weakened peripheral pulse. ETCO2 can therefore be an early warning of developing shock, or pulmonary embolus.

If ETCO2 drops to zero, then the heart has stopped. This is true even for patients who are continuing to receive manual ventilation, because although air is moving into and out of the lungs, there is no CO2 being delivered to exhale. Loss of ETCO2 can also be the first sign of cardiac arrest. A patient may still have an EKG trace in pulseless electrical activity, but not have circulation and therefore will not have a measurable ETCO2.

Here is a simplified flow chart for using ETCO2 to alert you to perfusion or ventilation problems.

ETCO2 is a valuable tool for early recognition of poor perfusion and cardiac arrest.

ETCO2 is a valuable tool for early recognition of poor perfusion and cardiac arrest.

Adequacy Of Chest Compressions

Good quality CPR depends on high quality chest compressions. When I practice with my staff during Critical Event Training, failure to perform adequate chest compressions is common, a fact that reinforces the need to routinely practice.

During one particular exercise, one diminutive RN was having trouble making her compressions meet the 2-2.5 inch depth, 100 compressions per minute on the manikin (as measured by our test device). The rest of the team encouraged her until she got it correct. The following weekend her Dad suffered a cardiac arrest in her living room. She went into action delivering chest compressions while the family dialed 911. Her father made a full recovery, and she gave credit to the training she had just received.

Good quality compressions can save lives. ETCO2 is one valuable tool we have to tell us that good quality compressions are being delivered. The higher the ETCO2 measured during compressions, the better the perfusion being supplied by CPR. The goal should be to maintain ETCO2 no lower than 10-20 mmHg. An ETCO2 below 10 mmHg is associated with poor outcome.

Good quality chest compressions will also generate a waveform on the ETCO2 capnograph that allows you to estimate the rate of compressions.

Return of Spontaneous Circulation

Return Of Spontaneous Circulation (ROSC) is accompanied by a sharp rise in ETCO2, usually within a range higher of 35-45 mmHg or higher as CO2 is now delivered to the lungs and then exhaled. This is often accompanied by a palpable pulse and a rising blood pressure.

Good news. However, the next 10 minutes are a very dangerous time for your patient. The heart is still stunned and cardiac output may still be poor. Current consensus guidelines for cardiopulmonary resuscitation (CPR) recommend that chest compressions resume immediately after defibrillation attempts and that rhythm and pulse checks be deferred until completion of 5 compression:ventilation cycles or minimally for 2min.

One study showed that perfusion remained poor for greater than 2 minutes in 25% of patients successfully defibrillated [1]. Continue to monitor that ETCO2! This is now your powerful tool to see if perfusion is adequate and being maintained. Assuming ventilation is consistent, a drop in ETCO2 during this period can indicate failing circulation. A loss in ETCO2 can mean re-arrest.

Check to make sure your endotracheal tube is still properly positioned, check a pulse, and decide your appropriate actions.

Prognosis During CPR Efforts

ETCO2 below 10 mmHg can be caused by poor compression technique.  It can also be caused by low perfusion and metabolism from prolonged shock despite good compressions — in other words the cardiac pump is damaged and failing. If high quality compressions are being delivered, and an advanced airway is in place allowing accurate ETCO2 measurements, then an ETCO2 persistently below 10mmHg after 20 minute of resuscitation is a poor prognostic sign. It can be used as an indication to consider terminating resuscitation efforts.

On the other hand if ETCO2 is above 15mmHg, or it continues to rise, that is one indication that resuscitation efforts should continue, as the brain and heart are being perfused. There are case reports of patients surviving prolonged CPR with higher ETCO2 readings.

We’ve come a long way since I had to depend on a precordial stethoscope, skin color and finger on the pulse to supplement blood pressure and EKG to assess perfusion in my patients. Capnography and pulse oximetry are powerful tools. However, don’t forget that in the absence of either, you can still look at your patient and be vigilant. Without vigilance, all the tools in the world will not protect your patient.

May The Force BeWith You

Christine E Whitten MD, author
Anyone Can Intubate: A Step By Step Guide
and
Pediatric Intubation: A Step By Step Guide

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      Button to see inside or buy the book Pediatric Airway Management: A Step-by-Step Guide by Christine Whitten

References

1. Pierce AE, Roppolo LP, Owens PC, Pepe PE, Idris AH. The need to resume chest compressions immediately after defibrillation attempts: an analysis of post-shock rhythms and duration of pulselessness following out-of-hospital cardiac arrest. Resuscitation. 2015 Apr;89:162-8. doi: 10.1016/j.resuscitation.2014.12.023. Epub 2015 Jan 15.

Bilateral Tension Pneumothorax: Harder To Diagnose

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. Continue reading

Anatomic Dead Space Affects Hypoventilation

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

NITROUS OXIDE: SHOULD WE USE IT?

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

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

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

Close Call In Honduras With A Nosebleed

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

Intubation With Airway Bleeding and Massive Emesis

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

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

Ventilation Perfusion Mismatch

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

Help! My Anesthesia Machine’s Not Working!

There is nothing quite as scary as being in the middle of administering an anesthetic and having your anesthesia machine fail. In my 36 years of anesthesia practice I’ve had this happen to me a few times. Knowing how to quickly troubleshoot your machine, and knowing how to protect your patient are important, potentially life-saving skills. It helps to have thought through the steps to rescue the situation before it happens to you.

Here I describe how I learned this lesson the hard way on a volunteer medical mission to rural Honduras. When my machine failed, I was poorly prepared and this forced crisis management that I could easily have avoided with a little forethought and preparation.
Continue reading

Codeine Risk In Children, Especially Those With Sleep Apnea

Although the initial FDA warnings about potentially fatal overdose from codeine in children were released in 2012, I’m recently discovered that a few of my surgeon and nursing colleagues were still unaware of the potential risks. Therefore I thought it might be helpful to bring up the topic so people can remind their own colleagues of the risks of codeine in children.

Codeine must be used with extreme caution, if at all, in young children or pregnant women because of variants in the enzymes some patient’s use to metabolize the drug. Continue reading

Alert: We May All Be Over-Inflating Our LMA Cuffs!

 

Since its invention, the Laryngeal Mask Airway, or LMA, has become quite valuable as a surgical airway alternative to intubation. When I first started in anesthesia, the only way to avoid intubation during surgery was to manually assist ventilation with a bag-valve-mask attachment. Cases that went on for hours often resulted in cramped fingers, and sometimes progressively poorer ventilation over time as the hand holding the mask became overly tired. A poor mask seal could potentially cause the stomach to distend with air, pushing up the diaphragms, limiting tidal volume, and increasing the risk of aspiration. The LMA has changed anesthesia so much that residents now find it challenging to find cases to practice their masking skills.

However, the LMA is so commonly used, and so apparently safe, that it’s easy to become complacent. Research is showing that it’s apparently very common for us to over-inflate our LMA cuffs — to the potential harm of our patients. Continue reading

Potential Tongue Ischemia with LMA Supreme

When we place anything in the mouth, be it an endotracheal tube, oral airway or LMA, we are typically extremely careful to protect the teeth. We take care to avoid cutting the lips with the teeth. But we often take the safety of the tongue for granted. I recently recognized a potential problem while using an LMA supreme that could have caused tongue ischemia if not corrected. Let we show you what happened so you can be on guard with your own patients.  Continue reading

Apneic Oxygenation: Increase Your Patient’s Margin Of Safety During Intubation

While breathing room air, oxygen saturation drops precipitously to below 90% within about a minute of the start of apnea in the average healthy adult. As we saw in a previous blog post, preoxygenation is one of the most important safety measures we can use prior to induction of anesthesia and in preparation for intubation. Adequate preoxygenation can more than double the time to hypoxia during open airway apnea, allowing more time for intubation to occur. However, increasing the time to critical hypoxia from 1 minute to 2 or 3 minutes with preoxygeation, as important as that is, can still be too short if the intubation turns out to be truly challenging. Apneic oxygenation is an easy technique to increase the time to desaturation significantly. However you have to know how to optimally provide it in order to safeguard your patient  Continue reading

Preoxygenation Can More Than Double The Time To Hypoxia During Apnea

While breathing room air, oxygen saturation drops precipitously to below 90% within about a minute of the start of apnea in the average healthy adult. One of the most important safety measures we use in anesthesia is to preoxygenate our patients prior to induction of anesthesia and in preparation for intubation. This is especially true if we are planning a rapid sequence induction. Adequate preoxygenation can more than double the time to hypoxia during apnea, allowing more time for intubation to occur.

Preoxygenation increases the margin for safety. It treats any pre-existing hypoxemia in the critically ill patient. It also postpones the onset of hypoxia while the patient is apneic during the intubation attempt. This becomes especially important if the intubation attempt becomes difficult and prolonged.

Speed of onset of hypoxia with apnea depends on metabolic rate and on the actual amount of oxygen available in the patient’s functional residual capacity. To see how preoxygenation can effect this let’s review some physiology. Continue reading

Don’t Withhold Oxygen From That CO2 Retainer

There is often a great deal of confusion about how to manage the care of a patient with COPD because of unwarranted, and incorrect, concern that all patients with COPD are CO2 retainers. This fear of causing CO2 retention sometimes causes providers to withhold or withdraw oxygen inappropriately. Understanding some of the respiratory physiology behind CO2 retention will allow you to make more informed decisions. Let’s start at the beginning. Some of this material comes from my book Anyone Can Intubate, 5th Edition. Continue reading

To Extubate, Or Not to Extubate, That Is The Question

Assessing extubation criteria, and then deciding when to extubate a patient safely can sometimes be a difficult decision.

Extubation Criteria

We all know the common extubation criteria:

  • recovery of airway reflexes and response to command;
  • inspiratory capacity of at least 15 ml/kg;
  • no hypoxia, hypercarbia, or major acid/base imbalance;
  • no cardiopulmonary instability;
  • signs of intact muscle power;
  • absence of retraction during spontaneous respiration;
  • absence of a distended stomach.

In other words, you want your patient to be stable, able to breathe without help, and able to protect the airway.

However, sometimes the decision is not so easy. Here I describe a case of a patient who met some but not all of the criteria for extubation. The reason turned out to be due to a rare complication: plugging of the endotracheal tube. However, getting to that solution required working through the extubation algorithm.  Continue reading

Ventilate and Intubate But Don’t Forget Communicate

Failure to communicate, and making assumptions rather seeking true facts,  can endanger your patient. Many years ago I was participating in a volunteer medical mission to Kenya when I learned a valuable lesson in communication which I often share with my students. In this case, multiple providers made bad assumptions about what the others knew that led to a potentially dangerous situation involving intubation.
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Avoiding Medication Errors

Humans are fallible and unfortunately medication errors can occur easily. On my hospital’s wards, and indeed on most hospital wards, when medications are drawn up, the nurse must check the medications, dosage and labeling with another nurse before administering the medication. In fact, in my hospital the pharmacist also checks all of the orders to make sure allergies and other drug conflicts have not been overlooked. This is a wonderful safety feature, but it’s time consuming and labor intensive.

In the OR, during anesthesia, things are happening quickly – too quickly to have a second person constantly checking each medication draw. The anesthesia provider is drawing and administering the medications solo. That added responsibility means we have to be extra vigilant. There are many things that can predispose to medication error

A Mistake From My Own Past

Picture of multiple syringes and vials on a work station

It’s easy to grab the wrong syringe if your work station is not organized.

It can happen to anyone, even me. About twenty five years ago I was giving a routine “local with sedation” anesthetic in a healthy patient. One of the CRNAs came in to see if I needed anything. As I was talking to my colleague, my patient said he was still nervous. I told the patient, who had already received some valium, that I would give him a “little more medicine that would help him relax“. At that point I accidentally picked up the 5 ml anectine syringe rather than the 5 ml valium syringe. Continue reading