Choice of Anesthetic Technique

1. What are the choices for anesthetic technique available?

• General Anesthesia: Provides unconsciousness so the patient does not feel, see of hear anything during a surgical procedure.

• Conscious Sedation AKA Monitored Anesthetic Care: Patients breathe without assistance, are more responsive to painful stimuli, and show less effect on heart and blood pressure.

• Regional Anesthesia: Local anesthetics are injected to numb the nerves the supply sensation to the operated body part.

• Epidural Anesthesia: A catheter is placed in the epidural space to continuously deliver anesthetics.

• Spinal Anesthesia: A spinal needle is inserted and used to inject anesthesia directly through the needle. No catheter is involved.

2. Describe the events involved in rapid sequence induction

The goal of RSI is to minimize the time between when a patient cant protect their own airway (i.e. when they are awake and responsive) and when the anesthesiologist protects their airway for them (i.e. when the tube is in), in order to minimize the time the patient is at risk for aspiration.

Another major difference is that there is no bag-mask ventilation, as this could introduce air into the GI track causing vomiting. The steps for RSI are below:

• Preparation: check Allergies, Medications, Past med hx, Last meal, Events surrounding incident (AMPLE). Also check supplies and monitors.
• Preoxygenate: 100% for 3 minutes (spontaneous breathing).
• Pre-treat: opioids to reduce sympathetic response to intubation, raglan to reduce risk of gastric aspiration syndrome
• Paralysis and anesthesia: IV induction followed immediately by succinylcholine, often use propofol due to its anti- emetic action.
• Pass tube: immediately following fasiculations from succinylcholine
• Post-tube management: tape tube, opioids, etc, etc.

Cricoid pressure may or may not be applied (evidence poor that this significantly reduces aspiration).

3. When is RSI used?

Patients at aspiration risk (e.g. meal < 8 hours OR history of uncontrolled reflux OR recently vomiting) may receive Rapid Sequence Induction.

4. What are the objectives during maintenance of general anesthesia?

• Physiologic Homeostasis: Including heart rate, BP, temperature, oxygenation.
• Anterograde Amnesia: To ensure patients do not remember surgery. Achieved through benzodiazepines and/or unconsciousness 2/2 deep anesthesia.
• Analgesia: Achieved through analgesics, nerve blocks and/or unconsciousness 2/2 deep anesthesia.
• Immobility: To optimize surgical conditions. Either through a neuromuscular blocker or deep anesthesia.

5. Why is N2O administered in combination with volatile anesthetics?

Generally, the greater the dose of anesthetic used, the greater the likelihood of side effects. As a result, lower doses of multiple anesthetic agents are combined together to achieve the same level of anesthesia as a singe agent, but with fewer side effects. Nitrous Oxide is administered as an adjunct to reduce the amount of inhaled or IV anesthetic required. It is cheap, wears off quickly (and reliably), has minimal myocardial depression and few other side effects.

6. Neuraxial anesthesia is selected primarily for what surgical sites?

Spinal and epidural blocks provide excellent anesthesia for procedures of the lower extremities as well as low abdominal and pelvic surgery. Spinal and epidural blocks are also used to provide obstetrical and post-operative analgesia.

7. What are some of the advantages of peripheral nerve block?

• Improved Analgesia: In a meta-analysis, peripheral nerve blocks outperformed opioids in post-op pain control with fewer side effects.
• Decreased hospital and PACU stay
• Improved blood flow to extremity due to sympathectomy.
• Improved post-op functional recovery.
• Improved patient satisfaction

8. Define MAC

Monitored anesthesia care (MAC), also referred to as “conscious sedation” or “local with sedation”. Many procedures are of such an atraumatic and minimally invasive nature they can be performed with an awake but sedated patient. Some procedures can be performed with sedation, with or without local anesthesia administered in the field by the surgeon. Examples of such procedures include colonoscopies, breast biopsies and others. The anesthesiologist is responsible for monitoring the patient, determining and administering a correct level of sedation appropriate for the procedure and for patient comfort and safety. As above, supplemental oxygen is usually provided via nasal cannulae. Small doses of medications are administered to minimize anxiety, promote sedation, and provide analgesia as well as amnesia for the intraoperative period. The patients are monitored for the duration of the procedure and the adequacy of their analgesia is frequently reassessed. At the conclusion of the procedure, the patient is transferred to the PACU where monitoring continues.

9. Clinical Scenarios for choice of anesthetic technique

For the following clinical scenarios, discuss your choice of anesthetic technique and the rationale for that choice: