Rapid sequence intubation (RSI) is an emergent procedure used to secure the airway in acutely unstable patients. It involves the use of an induction agent to induce unconsciousness, followed immediately by a neuromuscular blocking agent for paralysis so that the clinician can safely intubate the patient by minimizing the time the patient’s airway is unprotected.
Preparation
Start by assessing the patient for anatomical features or physiologic findings that would potentially make them difficult to intubate or ventilate using a bag-valve-mask. For example, obese patients are classically presumed to be difficult intubations because of their body habitus often making it difficult to maneuver the laryngoscope in order to locate your anatomical landmarks. Also consider physiological derangements such as hypotension or shock as these clinical scenarios may put patients at risk for post-intubation hypotension or cardiac arrest.
These anatomically difficult patients and physiologic derangements may lead to complications that may prolong the time to successful intubation, thus prolonging the patient’s apneic time. Having a plan to correct these derragement prior to intubation may prevent these poor outcomes, further increasing the chance of a successful intubation on the first attempt.
Have an airway management plan in place from the very beginning. This would include gathering the necessary equipment and medications, in addition to formulating a plan to correct physiologic derangements, such as intravenous fluids in septic shock, and optimizing positioning in cases of difficult anatomically airways.
Have a backup plan to account for any potential difficulties or complications resulting from RSI. Remember that the goal of preparation is to maximize the chances for successful intubation on the first attempt.
Preoxygenation
Preoxygenation creates an oxygen reservoir in the lungs, blood, and tissues that enables patients to tolerate a longer period of apnea without desaturation. This can be achieved with flush-flow oxygen for at least three minutes and passive oxygenation via high-flow nasal cannula thereafter is recommended for all patients being intubated with RSI. In certain clinical scenarios, you may even consider the use of non-invasive ventilation to achieve a desirable oxygen reserve in order to facilitate a longer period of apnea without desaturation. Keep in mind that the time to desaturation can vary depending on age, gender and most importantly those who are critically ill. For example, a study demonstrated the time to desaturation less than 90 percent after apnea during RSI for preoxygenated patients of different ages and conditions:
- Healthy 70-kg male: 6 to 8 minutes
- Young children (10 kg): <4 minutes
- Adults with chronic illness or obesity: <3 minutes
- Women at near full-term pregnancy: <3 minutes
Critically ill patients in the ED or intensive care unit (ICU) often desaturate even more quickly, if not immediately.
Pre-intubation optimization
During the preparation phase, the provider should have recognized any anatomical features or physiological derangements that would make RSI more difficult.
Unless the need for intubation is immediate, patients should be physiologically optimized prior to the procedure. This includes the identification of the underlying pathology and attempting to treat and manage the patient accordingly. This may include intravenous fluids, blood products, and vasopressors as necessary in cases of septic shock, or the placement of chest tubes in cases of hemopneumothorax in trauma and the continued preoxygenation for all patients.
Paralysis with induction
Your induction agent and paralytic of choice should have been chosen prior to this point and after optimizing your patient’s conditions, the induction agent and paralytic are administered almost simultaneously. The goal of this step during RSI is to achieve sedation and paralysis 45 to 60 seconds after the administration of the medications via IV push. Specific induction agents and neuromuscular blocking agents are discussed separately.
Protection and Positioning
For patients that are not immobilized (such as a cervical collar) are placed in a sniffing position, where the patient is supine with a 20 degree head-up position. In immobilized patients, 30 degree reverse Trendelenburg positioning may be used.
After successful induction and paralysis, bag-valve-mask generally should not be performed in patients who were successfully preoxygenated to prevent the risk of regurgitation and aspiration.
Cricoid pressure was previously recommended during RSI in the emergent setting, however this is no longer recommended. This maneuver was previously used to prevent gastric insufflation and the regurgitation of gastric contents during bag-mask ventilation, however evidence has been conflicting whether or not this maneuver is successful in achieving this. Additionally, if preoxygenation was performed successfully, bag-mask ventilation is unnecessary during this period of apnea during RSI.
The downside in performing this maneuver is that it may cause some degree of airway obstruction making it more difficult to intubate. As a result, cricoid pressure during RSI in the emergent setting is generally no longer recommended.
Placement with proof
After the administration of your induction agent and paralytic, complete neuromuscular relaxation should be achieved within 45 to 60 seconds, and at this point, laryngoscopy is performed. Once the glottis is visualized, the endotracheal tube (ETT) is passed between the vocal cords, the ETT cuff is inflated and the stylet is removed.
The next step is to confirm the proper placement of the ETT within the airway and not mistakenly placed into the esophagus.
ETT placement within the airway is confirmed by many different ways, however the most accurate way is with the use of waveform capnography. Other options for confirmation include the use of capnometry or colorimetric end-tidal CO2 devices. Adjuncts to these confirmation methods include the visualization of the ETT through the cords, condensation within the ETT with ventilation and the auscultation of breath sounds over lung fields. However these clinical indicators should not be used alone to confirm proper ETT placement. Additionally, single-view chest x-rays are often obtained after the placement of the ETT, however this is used to determine the depth of placement and should not be used to confirm proper placement of the ETT within the airway.
Postintubation Management
After confirming the placement of your ETT within the airway, your ETT is secured in place. This can be achieved by taping or tying the ETT or using specifically designed tube holders.
As mentioned previously, a post-intubation chest radiograph is obtained to confirm the depth of the ETT and to assess for any barotrauma from positive pressure ventilation. The radiograph is not used to confirm the proper placement of the ETT within the airway because of the proximity of the esophagus to the trachea.Ocne proper depth of the ETT is confirmed, adjustments to the ventilator can be made according to the clinical circumstances of the patient.
A sedative and/or analgesic agent should be considered in the post-intubation period to prevent discomfort or agitation of the patient especially since the medications typically used during RSI have a relatively short duration of action compared to the longer duration anticipated for the patient to be mechanically ventilated.
During this period after the confirmation of your ETT, some patients may declare themselves hypotensive or hypoxic. If these do not resolved after appropriate treatment of the underlying pathology of your critically ill patient, such as with IV fluids or with positive pressure ventilation, then the clinician should search for potential complications of intubation and ventilation such as barotrauma/pneumothorax, ETT cuff rupture or air leak, oxygen circuit malfunction, mucus plugging and reconsideration of an esophageal intubation.
Indications and Contraindications to Rapid Sequence Intubation
Indications for RSI are simply those patients who cannot ventilate, oxygenate or fail to protect their aiway. Contraindications are few and relative.
The ICU Book
A fundamental and respected resource in critical care. Including a review of various common critical care pathology, ariway and mechnical ventilation.
Choosing an Induction Agent
Induction agents used in rapid sequence intubation all lead to a similar endpoint which includes providing sedation and amnesia and can improve intubating conditions.