The Core Principle of RSI Medication Order
Rapid Sequence Intubation (RSI) is a highly structured procedure designed to secure a definitive airway quickly and safely, minimizing the risk of aspiration. The fundamental principle of medication administration is to render the patient unconscious with an induction agent (sedative) immediately before inducing neuromuscular blockade with a paralytic agent. This sequence ensures the patient does not experience the terrifying sensation of being paralyzed while awake.
The entire process is often broken down into a mnemonic, the "7 P's of RSI", which provides a systematic framework for the procedure, including drug administration.
The 7 P's of RSI: A Step-by-Step Breakdown
Clinicians follow these steps to ensure all aspects of the procedure are addressed in the correct order.
1. Preparation
This phase occurs before any drugs are given. It involves gathering all necessary equipment (laryngoscopes, endotracheal tubes, suction), assigning team roles, and developing a clear plan, including backup airway strategies.
2. Preoxygenation
For a specific duration, the patient receives 100% oxygen. The goal is to "de-nitrogenate" the lungs, creating a vital oxygen reservoir that allows for several minutes of apnea without significant oxygen desaturation while the intubation is performed.
3. Pretreatment
This step is optional and its routine use has fallen out of favor due to limited evidence for improved outcomes outside of specific scenarios. Historically, the "LOAD" mnemonic (Lidocaine, Opioid, Atropine, Defasciculating dose) was used. These drugs, when used, are typically given a specific time before induction to mitigate some of the adverse physiological responses to laryngoscopy, such as increased intracranial pressure (ICP) or bronchospasm. Fentanyl may still be considered in cases of aortic dissection or ischemic heart disease, and lidocaine may be used in patients with suspected elevated ICP.
4. Paralysis with Induction
This is the critical medication administration step. An induction agent (sedative) is given as a rapid IV bolus to produce unconsciousness. Immediately following this, a paralytic agent (neuromuscular blocking agent) is administered. While traditionally the sedative is given first, some studies show that administering the paralytic just before or at the same time is also acceptable and may modestly speed up time to intubation. The non-negotiable rule is to ensure the onset of sedation occurs before the onset of paralysis.
5. Protection and Positioning
During the onset of the medications, the patient's airway is protected. Proper patient positioning (e.g., "sniffing position") is optimized to align the airway axes for the best view during laryngoscopy.
6. Placement with Proof
Once the patient is fully sedated and paralyzed (typically after a specific duration), the clinician performs laryngoscopy and places the endotracheal tube. Placement is immediately confirmed using methods like end-tidal CO2 detection, listening for bilateral breath sounds, and observing chest rise.
7. Post-Intubation Management
Immediately after securing the tube, the focus shifts to providing long-term sedation and analgesia. This is critical because the RSI drugs are short-acting, and failure to provide continued sedation can lead to the patient waking up while paralyzed and connected to a ventilator.
Comparison of RSI Induction Agents
Choosing the right induction agent depends heavily on the patient's clinical condition, particularly their hemodynamic stability.
| Agent | Onset | Duration | Key Advantage | Key Disadvantage/Contraindication |
|---|---|---|---|---|
| Etomidate | Rapid | Short | Minimal cardiovascular depression; ideal for unstable patients | Adrenal suppression, myoclonus, pain on injection |
| Ketamine | Relatively rapid | Moderate | Bronchodilatory and provides cardiovascular support (increases heart rate and blood pressure) | Increases secretions; caution in patients where hypertension/tachycardia is undesirable |
| Propofol | Very rapid | Short | Rapid onset and short duration | Significant hypotension and myocardial depression; best avoided in unstable patients |
Comparison of RSI Paralytic Agents
The two most common paralytics used for RSI are succinylcholine and rocuronium.
| Agent | Onset | Duration | Key Advantage | Key Disadvantage/Contraindication |
|---|---|---|---|---|
| Succinylcholine | Very rapid | Very short | Fastest onset and very short duration, allowing for quicker return of spontaneous respiration if intubation fails | Numerous contraindications (hyperkalemia, malignant hyperthermia, crush injuries >5 days old), causes fasciculations |
| Rocuronium | Rapid | Long | Fewer contraindications than succinylcholine; action can be reversed with sugammadex | Much longer duration of action, requiring diligent post-intubation sedation to prevent awareness |
Conclusion
The correct order for RSI drugs centers on a single principle: sedation before paralysis. The process begins with optional pretreatment agents, followed by the rapid administration of an induction agent and then immediately a paralytic agent. The choice of specific drugs is tailored to the patient's individual physiology and clinical context, with the overarching goals of maximizing intubation success, ensuring patient safety, and preventing awareness during paralysis. Following a structured approach like the 7 P's ensures these critical steps are performed safely and effectively every time.
For further reading on airway management, consider resources from the American College of Emergency Physicians (ACEP).
Disclaimer: This information is for general knowledge and should not be taken as medical advice. Consult with a healthcare professional before making any decisions related to medical treatment or procedures.
