Induction of general anesthesia explained step by step

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.