Emergency Airway Management Part 5: Post intubation care

Case

A 55-year-old man was found unconscious in the bathroom by his family. He has a GCS of 7. His vital signs on arrival are a heart rate of 130, a blood pressure of 90/55, a respiratory rate of 28, and an oxygen saturation of 89% on room air. After using basic airway maneuvers to temporarily stabilize his airway, you were able to take the time to appropriately resuscitate and pre-oxygenate him, prior to proceeding with intubation. You pass the tube easily on the first attempt. Looking around the room for someone to high-five, you realize your team is waiting for your instructions for the ongoing care of this sick patient…

My approach

Confirm ETT placement and secure the tube

Confirming tube placement is, in my mind, an essential step of the intubation procedure itself, but is important enough to be repeated here. Confirm placement with quantitative end-tidal capnography, and then leave the waveform capnography in place for monitoring purposes. (Apfelbaum 2013; Frerk 2015) Take a moment to secure the tube, so your hard work is not undone. (I have always left the method of securing the tube to our excellent RTs. I am not aware of any evidence that any one technique of securing the endotracheal tube is better than others, but would love to hear about studies if they exist. It makes sense to use the same technique favoured by your ICU, to avoid the unnecessary risk of changing devices later.)

Continue Resuscitation

In the emergency department we intubate critically ill patients. The plastic tubing of the endotracheal tube is very rarely the definitive treatment required. In fact, the transition to positive pressure ventilation is often detrimental to the patient’s hemodynamics. The procedure of intubation requires focus, which can result in a loss of awareness of the patient’s overall status. Ideally, critically ill patients are managed by multiple physicians, allowing one to focus on the airway while another leads the overall resuscitation. (Brindley 2017) However, this simply is not feasible in some clinical environments. My first step after confirming endotracheal tube placement is to ensure I have adequate situational awareness, repeat a primary survey, get a repeat set of vital signs, and address any immediate life-threats.

Start analgesia and (+/-) sedation

Immediately after my primary survey, I confirm that the patient has been given an analgesic. Ideally, post-intubation analgesia is ordered before intubation so that it can be given by a nurse while I perform my post-intubation primary survey.

Start with analgesia. Get an opioid on board. This can be a fentanyl drip. It can be boluses of morphine or hydromorphone. (It is generally easier to start with boluses in the emergency department. Drips just seem to take too long to get setup. However, it is easy to get distracted as new patients come in, so transitioning to a drip as soon as possible also makes sense.) Whatever opioid you are comfortable with is fine. The key is to rapidly titrate it to a point that the patient is pain free. The central agent in the post-intubation package is an analgesic, not a sedative. (Strom 2010)

However, most patients are going to find the resuscitation bay to be anxiety provoking. Having an anxiolytic on board also makes sense. Why not just load the patient up with benzos and let the ICU figure it out later? Deep sedation early in a patient’s course has been associated with increased delirium, longer ICU stays, and increased mortality. (Pisani 2009; Fraser 2013; Shehabi 2012; Peitz 2013) Benzodiazepines in particular should probably be avoided, as they are associated with a longer ICU length of stay and longer durations of mechanical ventilation. (Fraser 2013) (Delirium tremens is an exception to this rule, and benzodiazepines are required.) For most of us, a small dose of propofol is probably sufficient. If you have dexmedetomidine available to you, it is also a good option.

The goal is light sedation, so that the patient is drowsy but will respond to voice (assuming that they were able to respond before intubation). Using the Richmond Agitation Sedation Scale, this would translate to a range between 0 and -2. Using a sedation scale makes sense, and for ease of transition to the ICU, I would recommend adopting whatever scale is used in your ICU.

A brief summary of some of the commonly used post-intubation medications can be found here.

Special case: the hypotensive patient

If you need to start a vasopressor in order to give analgesia and sedation, do it. If you need to titrate up the vasopressor, or add a second vasopressor, as you increase your analgesia and sedation, do it. Practically speaking, when I start out worried about hypotension, I titrate small boluses of fentanyl (25-50 mcg at a time) while optimizing the blood pressure. (Don’t forgot to continue to treat the underlying cause of the hypotension). Once I think I have pain adequately controlled, I will add ketamine as my secondary agent. I also think ketamine alone is a reasonable strategy in hypotensive intubated patients, but it is a strategy without good evidence to support it.

Raise the head of the bed (if not contraindicated)

Almost all critically ill patients should be positioned with the head of the bed up. Ventilation and oxygenation are improved in an elevated position. Raising the head of the bed to 45 degrees is also important in the prevention of aspiration and ventilator-associated pneumonia. (VAP occurs in 10-20% of patients ventilated for more than 48 hours, and is associated with a high rate of mortality.) (Grap 2012; Singer 2009)

Set the vent (initial settings)

People spend a lot of time talking about ventilator modes – SIMV, pressure assist-control, volume control, APRV. For the initial management in the emergency department, it really doesn’t matter. No ventilator mode has ever been shown to be better than the others. (If you want a great primer on the various vent modes, this article by Rory Spiegel and Haney Mallemat is the best I have read.) What matters is having a basic understanding of the tidal volume, respiratory rate, FiO2, and PEEP, and why you are adjusting those numbers. Keeping things simple, I adjust the tidal volume for lung protection, the respiratory rate to adjust ventilation (CO2), and the combination of FiO2 and PEEP to adjust oxygenation.

I have 3 basic strategies for my initial ventilator settings: the bronchospasm strategy, the metabolic acidosis strategy, and everyone else.

Basic settings (Lung protective strategy – most patients)

Most patients get the lung protection strategy. It is the strategy specifically developed for ARDS patients, and although evidence is lacking for non-ARDS patients, it is a reasonable starting point for most patients. (Weingart 2016) The key to this strategy is low tidal volumes (because lungs full of pus or fluid cannot tolerate the same volume of air as healthy lungs). (Spiegel 2016; Weingart 2016; Singer 2009) My initial settings are:

• Tidal volume: 6-8 mL/ kg (Use ideal body weight. Estimate the height of the patient, and use an online calculator like MDCalc to calculate the ideal body weight.)
• Respiratory rate: 18 (Pay attention to the patient’s pre-intubation respiratory rate. Increase this rate if the patient is significantly tachypneic.)
• Fi02/PEEP: These are adjusted in tandem according the the ARDSnet protocol. Shortly after intubation, I will turn the FiO2 down to 40%, set the PEEP at 5 mmHg, then titrate up the table below to a target oxygen saturation of 88-95%.
• Inspiratory flow rate: This is the one other setting you will be asked about. It adjusts how quickly the breath goes in, and helps with patient comfort. Set between 60 and 80 L/min.

Bronchospasm strategy (asthma/COPD)

The first line strategy for patients with bronchospasm is to avoid intubation. Mechanical ventilation can make these patients a lot worse. (Weingart 2016) If you have to intubate a patient with obstructive lung disease, the priority is providing sufficient expiratory time. If the respiratory rate is too high, an inspiration can be triggered before the patient finishes expiring, resulting in excess air trapped in the lungs (breath stacking). Ultimately, this will lead to extremely high intrathoracic pressure, which can lead to difficulties ventilating and hemodynamic collapse. This strategy is all about avoiding breath stacking. (Weingart 2016; Singer 2009)

• Tidal volume: 8 mL/kg (ideal body weight)
• Respiratory rate: Start at 8-10/min. The respiratory rate is the key in these patients. We want an inspiratory to expiratory time ratio of 1:4-5. Adjust the respiratory rate down, allowing for hypercapnia, to improve expiration time.
• Fi02: Start at 40% and titrate to a sat of 88-95%
• PEEP: 0 (This is somewhat controversial. If you really know what you are doing, you can adjust the PEEP, but the safest strategy is to just leave this set at 0.)
• Inspiratory flow rate: A more rapid inspiratory time gives more time to expire, so increase slightly to 80-100 L/min.

Metabolic acidosis strategy

As was discussed in part 2 of the airway series, the best strategy for most metabolic acidosis patients is to avoid intubation altogether. However, when intubation is necessary, the priority is matching the patient’s baseline minute ventilation, which is essential for respiratory compensation of the metabolic acidosis. (It is also important to match the minute ventilation before the patient is on the vent, which means modifying RSI to include ventilations and bagging at a much more rapid rate than usual while the vent is being prepared, or using an awake approach to intubation.) My initial settings are: (Singer 2009; Spiegel 2016)

• Tidal volume: 10-12 mL/ kg (ideal body weight). This is a much higher tidal volume than usual, but in these patients it is incredible important to maintain the high minute ventilation. Be careful if the patient also has underlying pulmonary disease or ARDS.
• Respiratory rate: Try to match the patient’s pre-intubation respiratory rate. Will be at least 30.
• Fi02: Start at 40% and titrate to a sat of 88-95%
• PEEP: 0
• Inspiratory flow rate: 80-100 L/min (slightly increased to allow for the more rapid resp rate).

Adjust the vent

My initial vent settings are fairly similar for each patient, but that is not meant to imply that all patients require similar vent settings. The early stage of mechanical ventilation requires frequent reassessments to ensure that the patient is responding to and tolerating mechanical positive pressure ventilation. There are 4 key variables to assess in the mechanically ventilated patient: (Spiegel 2016)

1. Oxygenation
2. Ventilation (CO2 and pH)
3. Ventilator waveforms
4. Peak and plateau pressures

Titrating oxygenation

In the past, oxygenation was frequently dealt with by leaving the patient on 100% oxygen throughout their emergency department stay. However, we now know that prolonged hyperoxia is associated with harm in a number of conditions, so it is important to titrate oxygen down early. (Damiani 2015; Helmerhorst 2015; Spiegel 2016)

1. Turn the FiO2 down to 40%
2. Start with the PEEP at 5 mmHg
3. Target an oxygen saturation of 88-95%
4. Use the ARDSnet PEEP table to adjust both the FiO2 and PEEP

Titrating ventilation

Ventilation controls the CO2 level and is therefore important in pH balance. The primary adjustment will be respiratory rate, although tidal volume can also be adjusted if needed. (Spiegel 2016) The initial vent settings are dependant on the patient presentation. Adjustment is based on the blood gas, which should be sent shortly after intubation. Increase the respiratory rate to control hypercapnia and respiratory acidosis. For most patients, I target a pH >7.3 but allow some hypercapnia. (Spiegel 2016). However, for patients with airway obstruction, we might need to tolerate higher CO2s and lower pH to ensure adequate time for expiration to avoid breath stacking.

Checking the peak and plateau pressures

The peak pressure gives you information about airway resistance during inspiration, and so includes pressure produced by mucous in the airway, a small diameter endotracheal tube, and kinking of the endotracheal tube. While these are important considerations, when we are thinking about airway pressure, what we really care about are pressures that will cause damage to the lung. The pressure experienced at the level of the alveoli is best assessed using the plateau pressure. The plateau pressure is displayed only when you press and hold the “inspiratory hold” button on your ventilator. The target plateau pressures is less than 30 cm H2O. (Singer 2009) Lower plateau pressures by decreasing the tidal volume.

Assessing waveforms (avoiding breath stacking)

A lot of information can be obtained from the ventilator waveform, but my chief concern in the emergency department is avoiding breath stacking. As mentioned above, the primary aim of the ventilatory strategy for patients with asthma or COPD is to allow sufficient time for expiration. If a new breath is triggered before the patient has finished expiring, air will accumulate in the lungs, leading to increased intrathoracic pressures, difficulty ventilating, and ultimately hemodynamic collapse. Look at the flow waveform. If flow has not stopped before the next breath is triggered, you have breath stacking. (Weingart 2016; Singer 2009) The first step in this scenario is to decrease the respiratory rate, allowing more time for exhalation. A decrease in the tidal volume may also be required. In general, this will mean tolerating a higher CO2 and lower pH. This can be uncomfortable for the patient, so ensure they are adequately sedated. (Weingart 2016)

Continue to treat the underlying condition

Continuing resuscitation was step 2, immediately after confirming endotracheal tube placement, but there are usually a lot of things that need to get done. In the emergency department, we are really good at addressing immediate life threats, but critically ill patients usually require a large number of interventions. Take a moment to think about the patient’s care. What tests are required? Have appropriate antibiotics been given? Have pre-intubation bronchodilators been continued? I tend to use a head to toe approach to mentally ensure I have addressed all of the patient’s needs.

Checking tube depth

I will usually have an ultrasound machine with me in any resuscitation, so my rapid check is seeing lung sliding on both sides. However, at some point before I leave the room every patient will get a portable chest x ray to confirm the location of the tip of the endotracheal tube. (There is a double-black line on the ETT and, on intubation, this should be placed at the vocal cord level. As a general rule, this equates to approximately 20-22cm in women and 22-24 in men at the lips.)

Other stuff

Depending on the time that critically ill patients spend in the emergency department before being transferred to the ICU, it may be important to start other strategies to prevent ventilator-associated pneumonia. Chlorhexidine mouth washes should be started soon after intubation and continued every 12 hours thereafter. (Grap 2012) Routine suctioning of pulmonary secretions is important. (Grap 2012) All patients on the ventilator should be on humidified air. Endotracheal cuff pressures below 20 have been associated with increased rates of VAP. The target is a pressure between 20 and 30 cm H20. Cuffs will deflate over a few hours, so the pressures should be rechecked for any patients spending more than a couple hours in the emergency department. (Grap 2012) I also place a gastric tube to help prevent aspiration and provide a route for necessary medications.

Eye care is also important. Take the few seconds it requires to ensure the patient’s eyes are closed with appropriate tape if they are going to be sedated for any length of time.

What to do when the patient crashes on the vent

Vent alarms and the patient crashing on a mechanical ventilator will be covered in a future post on First10EM. For now, just make sure that you have all the equipment you might need easily available, such as a BVM, laryngoscope, bougie, and an airway exchange catheter, in case you run into any problems.

The rest of the airway series:

Part 1: Optimizing the basics

Part 2: Is this patient ready for intubation?

Part 3: Intubation

Part 4: Cricothyroidotomy

Part 5: Post intubation care

Notes

Once again, I am tremendously grateful for the guidance and peer review provided by both Dr. Laura Duggan (@drlauraduggan) and Dr. Casey Parker (@broomedocs ) for the entire airway series.

• Dr. Duggan has some incredible airway resources available at: http://www.airwaycollaboration.org/
• Dr. Parker runs one of the original FOAMed sites: http://broomedocs.com/

 

Other FOAMed Resources

The ARDSnet protocol

Post intubation package on EMCrit

Simplifying Mechanical ventilation on REBEL EM

A New Paradigm for Post-Intubation Pain, Agitation, and Delirium – EMCrit episode 115

A Bad Sedation Package Leaves your Patient Trapped in a Nightmare – EMCrit episode 21

PulmCrit- Fentanyl infusions for sedation: The opioid pendulum swings astray?

EMCrit Dominating the Vent Part 1 and Part 2

Post-intubation sedation and analgesia on Core EM

Life in the Fastlane: Setting up a Ventilator, Modes of Ventilation, ARDSnet Ventilation Strategy

Airway Resources on Emergency WA

References

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Brindley PG, Beed M, Law JA. Airway management outside the operating room: how to better prepare. Canadian journal of anaesthesia. 2017; 64(5):530-539. PMID: 28168630

Damiani E, Adrario E, Girardis M. Arterial hyperoxia and mortality in critically ill patients: a systematic review and meta-analysis. Critical care. 2014; 18(6):711. PMID: 25532567

Fraser GL, Devlin JW, Worby CP. Benzodiazepine versus nonbenzodiazepine-based sedation for mechanically ventilated, critically ill adults: a systematic review and meta-analysis of randomized trials. Critical care medicine. 2013; 41(9 Suppl 1):S30-8. PMID: 23989093

Frerk C, Mitchell VS, McNarry AF. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. British journal of anaesthesia. 2015; 115(6):827-48. PMID: 26556848 [free full text]

Grap MJ, Munro CL, Unoki T, Hamilton VA, Ward KR. Ventilator-associated pneumonia: the potential critical role of emergency medicine in prevention. The Journal of emergency medicine. 2012; 42(3):353-62. PMID: 20692786

Helmerhorst HJ, Roos-Blom MJ, van Westerloo DJ, de Jonge E. Association Between Arterial Hyperoxia and Outcome in Subsets of Critical Illness: A Systematic Review, Meta-Analysis, and Meta-Regression of Cohort Studies. Critical care medicine. 2015; 43(7):1508-19. PMID: 25855899

Pai MP, Paloucek FP. The origin of the “ideal” body weight equations. The Annals of pharmacotherapy. 2000; 34(9):1066-9. PMID: 10981254

Peitz GJ, Balas MC, Olsen KM, Pun BT, Ely EW. Top 10 myths regarding sedation and delirium in the ICU. Critical care medicine. 2013; 41(9 Suppl 1):S46-56. PMID: 23989095

Pisani MA, Kong SY, Kasl SV, Murphy TE, Araujo KL, Van Ness PH. Days of delirium are associated with 1-year mortality in an older intensive care unit population. American journal of respiratory and critical care medicine. 2009; 180(11):1092-7. PMID: 19745202

Shehabi Y, Bellomo R, Reade MC. Early intensive care sedation predicts long-term mortality in ventilated critically ill patients. American journal of respiratory and critical care medicine. 2012; 186(8):724-31. PMID: 22859526

Singer BD, Corbridge TC. Basic invasive mechanical ventilation. Southern medical journal. 2009; 102(12):1238-45. PMID: 20016432

Spiegel R, Mallemat H. Emergency Department Treatment of the Mechanically Ventilated Patient. Emergency medicine clinics of North America. 2016; 34(1):63-75. PMID: 26614242

Strøm T, Martinussen T, Toft P. A protocol of no sedation for critically ill patients receiving mechanical ventilation: a randomised trial. Lancet. 2010; 375(9713):475-80. PMID: 20116842

Weingart SD. Managing Initial Mechanical Ventilation in the Emergency Department. Annals of emergency medicine. 2016; 68(5):614-617. PMID: 27289336