Induction of general anesthesia explained step by step
By Max Feinstein
Anesthesia Induction: A Step-by-Step Guide
Key Concepts: General anesthesia induction, Ms Maids pneumonic, preoxygenation/denitrogenation, ventilation, intubation, monitoring, drug administration (midazolam, fentanyl, propofol, rocuronium), patient safety, situational awareness.
1. Introduction
Max Feinstein, an anesthesiologist, demonstrates the process of inducing general anesthesia on a simulated patient undergoing hernia repair. The video aims to provide insight into the thought process of an anesthesiologist during this procedure.
2. Pre-Induction Preparation and Situational Awareness
- Rapport and Collegiality: Emphasizes the importance of communication and teamwork in the operating room for patient safety.
- Equipment Check: Before approaching the anesthesia machine, the anesthesiologist identifies the location of emergency resuscitative equipment (defibrillator, bag valve mask).
- Ms Maids Pneumonic: A checklist used to ensure all necessary equipment and preparations are in place.
3. Ms Maids Pneumonic Breakdown
- M (Machine): Ventilator settings are programmed based on patient age and body weight to calculate ideal ventilatory settings and inhaled anesthetic gas dosage.
- S (Suction): Working suction is crucial for removing potential obstructions (vomit, blood) from the patient's mouth.
- M (Monitors): Attachment and assessment of monitors (blood pressure cuff, EKG, pulse oximeter) are essential. Baseline readings are obtained and analyzed.
- Example: A patient presented with a new irregular heart rhythm detected by the EKG, requiring further investigation before surgery.
- Heart Rate Analysis: A faster-than-expected heart rate is noted. Possible causes (anxiety vs. other medical issues) are considered.
- Audio Cues: Anesthesiologists are trained to recognize audio cues from the ventilator and monitors (e.g., blood pressure cuff cycling, heart rate pitch changes indicating desaturation).
- A (Airway): Verification of airway equipment functionality (laryngoscope light, endotracheal tube cuff integrity).
- Endotracheal Tube Cuff: The cuff inflates inside the trachea to create a sealed system for ventilation.
- Oral Pharyngeal Airways: Different sizes are available to maintain a patent airway by preventing soft tissue collapse.
- I (IV): Confirmation of a functional IV line.
- D (Drugs): Double-checking the availability of medications for anesthesia induction.
4. Induction Process
- Patient Communication: Addressing patient anxiety and explaining the procedure.
- Midazolam (Versed) Administration: A benzodiazepine administered for relaxation and amnesia.
- Dosage and Timing: Takes 10-15 seconds to take effect.
- Effect Monitoring: Observing the slowing of the patient's heart rate as an indicator of the medication's effect.
- Preoxygenation/Denitrogenation: Administering 100% oxygen to replace nitrogen in the lungs, increasing the patient's safe apnea time.
- Oxygen Concentration: Ambient air is approximately 21% oxygen.
- Mask Seal: Ensuring a good mask seal for effective oxygen delivery.
- Fentanyl Administration: An opioid administered to reduce the body's response to the intubation process.
- Pain Management: Reduces potential increases in blood pressure and heart rate during intubation.
- Drug Verification: Double-checking the medication, concentration, and amount before administration.
- Respiratory Suppression: Opioids, especially in combination with benzodiazepines, can cause respiratory suppression.
- Rocuronium Preparation: A paralytic agent prepared for administration after propofol.
- Propofol Administration: Anesthetic agent administered to induce unconsciousness.
- Patient Sensation: Describing the sensation as "warmth" to potentially reduce perceived discomfort.
- Onset Time: Typically takes effect in 10-20 seconds.
- Rocuronium Administration (Post-Propofol): Paralytic agent administered after the patient is unconscious.
- Onset Time: Takes 2-3 minutes for full effect.
- Eye Protection: Applying eye protection to prevent corneal abrasions.
5. Airway Management and Ventilation
- Bag Mask Ventilation: Manually ventilating the patient with 100% oxygen using a bag valve mask.
- Chest Rise: Observing chest rise as an indicator of adequate ventilation.
- Monitoring: Observing flow and end-tidal CO2 levels on the monitor.
- Laryngoscopy and Intubation: Using a laryngoscope to visualize the vocal cords and insert the endotracheal tube.
- Stylet: A flexible metal device used to maintain the shape of the endotracheal tube during intubation.
- Cuff Inflation: Inflating the endotracheal tube cuff to create a sealed airway.
- Ventilator Connection: Connecting the endotracheal tube to the ventilator circuit.
- Confirmation of Intubation: Verifying successful intubation through vital signs, tidal volume tracing, and end-tidal CO2 tracing.
- Ventilator Activation and Anesthetic Agent: Turning on the ventilator and initiating inhaled volatile anesthetic (sevoflurane).
- Securing the Endotracheal Tube: Securing the endotracheal tube with tape.
6. Conclusion
The video provides a detailed, step-by-step demonstration of anesthesia induction, emphasizing the importance of preparation, monitoring, and patient safety. It highlights the anesthesiologist's thought process and the rationale behind each action taken during the procedure.
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