In rapid sequence intubation we administer an induction agent, often etomidate, and a neuromuscular blocking agent (NMBA), succinylcholine or rocuronium, to render the patient unconscious and paralyzed for an emergency intubation after a period of preoxygenation and sometimes pretreatment with other medicines.
RSI is a procedure with seven steps: The Seven Ps of RSI (1)
They are: 1. Preparation 2. Preoxygenation 3. Pretreatment 4. Paralysis with induction 5. Positioning 6. Placement with proof 7. Postintubation Management
These are the steps we follow once the decision that intubation, for ventilatory support or for airway protection, is needed.
[8-22-2016: Dr. Scott Weingart of the outstanding EmCrit podcasts reminds us that the physiologically difficult airway (the airway in a patient with hypotension or potentional hypotension, the patient with hypoxia, and the patient with a severe metabolic acidosis) must also be planned for lest disaster (cardiac arrest) occur. Please review the following very carefully: Preoxygenation, Reoxygenation and Deoxygenation, Podcast 3 – Laryngoscope as a Murder Weapon (LAMW) Series – Ventilatory Kills – Intubating the patient with Severe Metabolic Acidosis, Podcast 104 – Laryngoscope as a Murder Weapon (LAMW) Series – Hemodynamic Kills, Podcast 173 – LaMW – Oxygenation Kills Part I, Podcast 174 – LaMW – Oxygenation Kills Part II, Podcast 129 – LAMW: The Neurocritical Care Intubation]
The first thing we do is to assess the patient for difficulty of intubation and for difficulty of bag mask ventilation if intubation fails. If the evaluation indicates a difficult airway, we will call for help and will use the difficult airway plan (perhaps an awake intubation if time permits. We will also make our plan for what we will do for a failed airway if that occurs.
We assemble and check all the equipment that we might require.
The patient needs at least one or two secure intravenous lines in place.
The patient needs full monitoring of his vital signs including cardiac monitor, respiratory rate monitor, blood pressure monitor, pulse oximeter, and continuous wave capnography.
All the medications need to be drawn up in syringes which are accurately labeled.
The purpose of this step is to use the lungs as an oxygen reservoir so that we, hopefully, do not need to use bag mask ventilation during the RSI. This will, again hopefully, prevent hypoxia and gastric aspiration.
We will administer to the spontaneously breathing patient an inhaled oxygen content that is as close to 100% as we can get.
It is important to realize that the “100% non-rebreathing mask” delivers an oxygen concentration of at most 65 to 75%.
We preoxygenate for three minutes or we can more rapidly achieve preoxygenation by asking the patient take eight vital capacity breaths of as close to 100% oxygen as our equipment permits (the patient breathes each breath as deeply as he can).
An obese patient should be preoxygenated sitting up 30% . Nasal cannula of 5 L per minute of oxygen provided during the intubation helps to delay oxygen desaturation during the intubation.
Preoxygenation will be discussed in greater detail in an upcoming blog.
Intubation and airway manipulation can have adverse physiologic effects on patients. These include marked sympathetic discharge causing increased heart rate and blood pressure, increase in intracranial pressure in patients with increased intracranial pressure, and bronchospasm.
When pretreatment is indicated (the ABC pneumonic) fentanyl and/or lidocaine is used.
Fentanyl is used to blunt sympathetic response in, for example, patients with increased intracranial pressure, intracranial bleed, aortic dissection, and ischemic heart disease.
Lidocaine is used for increased intracranial pressure or reactive airways disease.
The ABC pneumonic refers to Asthma (reactive airways disease), Brain (increased intracranial pressure) and Cardiovascular (ischemic heart disease, hypertension, aortic dissection).
When premedication is indicated, the drug or drugs, should be given 3 minutes before the induction agent and neuromuscular blocking agent.
There are many details to the use of pretreatment medications which are covered in chapter 20 and should be carefully reviewed. There are also times when the use of fentanyl may not be advisable (for example, in patients with sepsis or with compensated or decompensated shock). The chapter is worth careful review.
4. Paralysis with Induction
First an induction agent, often etomidate, is given by IV push. It is immediately followed by IV push of a neuromuscular blocker, succinylcholine or rocuronium. The authors recommend succylcholine unless there is a contraindication. However, they state that some practioners use only rocuronium for all intubations. Succinylcholine can cause fatal hyperkalemia in certain situations and it can uncommonly cause malignant hyperthermia. The disadvantage of rocuronium is that it’s onset is slightly longer than succinylcholine and its duration of paralysis is longer.
After 20 to 30 seconds the patient will be apneic and losing muscle tone. At this time the patient should be positioned for intubation. During this time the oxygen mask should remain in place so that even partial breaths are oxygen enriched.
Some patients will be so compromised that they will require bag mask ventilation throughout the procedure (except during the actual laryngoscopy) to keep their oxygen saturation at greater than 90%.
6. Placement with proof
Test the patient’s jaw for flacidity at 45 seconds for succinlcholine and at 60 seconds for rocuronium and intubate . It is critical to confirm the correct placement of the endotracheal tube. You must use a colormetric CO2 detector or better continuous capnography.
7. Postintubation Management
After the ETT is passed and it’s placement confirmed with certainty it is secured and mechanical ventilation is begun.
You need to get a chest x-ray to assess the lung fields and to make sure that a mainstem intubation hasn’t taken place.
Hypotension* is common after endoctracheal intubation and can be due to:
[*6-24-2017 Be sure to have your pulse dose pressor prepared and ready to go for any intubation as you never know. To view Dr. Weingart’s pdf click on mixing instructions for epinephrine and phenylephrine. To find more resources on push dose/pulse dose pressors type in “pulse dose pressors” into the search box.]
A. Tension pneumothorax– immediate chest tube needed.
Suspect when peak inspiratory presure is increased, there is increased difficulty with bag ventialtion, there is decreased breath sounds, and there is decreasing oxygen saturation.
B. Decreased venous return–fluid bolus, bronchodilators for increased airway resistance, increase inspiratory flow rate so you can increase expiratory time, try to decrease the tidal volume or the respiratory rate or both if the oxygen saturation is adequate, and decrease the dose of sedative.
Suspect in patients with high peak inspiratory pressure and in patients whose hemodynamic status was possibly compromised before intubation (compensated or decompensated shock, sepsis, dehydation).
C. Cardiogenic shock–cautious fluid bolus, pressors, decrease the sedation dose.
Suspect in patients with an abnormal ekg, in history consistent with this cause, and when bedside emergency cardiac ultrasound shows decreased cardiac function.
D.The induction agent–first exclude other cause, give fluid bolus, reduce sedation dose.
Basically, this is a diagnosis of exclusion.
Patients who have undergone RSI almost always require long-term sedation but neuromuscular blockade is avoided to the extent possible.
The patient must receive adequate sedation and analgesia.
Using a sedation scale such as the Richmond Agitation Sedation Scale (2) helps to prevent the use of inappropriate neuomuscular blockade when the cause of patient agitation is inadequate sedation.
“A reasonable sedation starting point is lorazepam 0.05 mg per kg or midazolam 0.1-0.2 mg per kg, compined with an analgesic such as fentanly 2 micrograms per kg, . . . . Fentanyl may be preferable [to other opiods discussed in the quote] because of its superior hemodynamic stability. When an NBMA is required, a full paralytic dose should be used (e.g., vecuronium 0.1 mg per kg).” (3)
When a neurological problem requires serial examinations, a propofol infusion may be a good choice because discontinuing it or decreasing it will lead to rapid return of consciousness.
But remember to use an analgesic with propofol because it is not an analgesic.
(1) The Manual of Emergency Airway Management, 4th ed. 2012. RM Walls and MF Murphy. pp. 221-226.
(2) The Richmond Agitation–Sedation Scale: Validity and Reliability in Adult Intensive Care Unit Patients Am J Respir Crit Care Med Vol 166. pp 1338–1344, 2002 available at http://ajrccm.atsjournals.org/content/166/10/1338.full.pdf. [This link is no longer valid. See reference 4 for another reference on the topic.]
(3) The Manual of Emergency Airway Management, 4th ed. 2012. RM Walls and MF Murphy. p. 225.
(4) Critical Care 2008 Volume 12 Supplement 3: Analgesia and sedation in the intensive care unit