S&P Lecture 2: Anesthsia

What training does an anesthesiologist complete?

A 4-year anesthesia residency

Which anesthesia provider can sometimes practice independently?

Some CRNAs (CAAs cannot)

What degree does a Certified Anesthesia Assistant (CAA) hold?

Master's degree (practice limited to certain states including Florida)

Minimum fasting time for SOLID food before anesthesia?

8 hours

Minimum fasting time for BREAST MILK before anesthesia?

4 hours

Minimum fasting time for CLEAR LIQUIDS before anesthesia?

2 hours

Which condition may prolong required fasting times?

Gastroparesis

Which upper airway exam findings suggest a difficult airway?

Limited cervical spine ROM, Short thyromental distance, Limited mouth opening, Poor dentition, Inability to protrude the jaw, Facial hair

Ideal thyromental distance?

More than 6 cm

Ideal mouth opening?

More than 3 cm

What is a normal jaw protrusion test?

Lower incisors can protrude past the upper incisors

When must the airway evaluation be documented?

Prior to the case

Mallampati class I?

Soft palate + tonsillar pillars + uvula visible — easy intubation

Mallampati class II?

Tonsillar pillars and part of uvula obscured by tongue — intermediate

Mallampati class III?

Only soft and hard palate visible — potentially difficult

Mallampati class IV?

Only hard palate visible — challenging airway

Which Mallampati classes indicate a high likelihood of difficult intubation?

Class III and IV

Does Mallampati class I or II rule out a difficult intubation?

No

When is the Cormack-Lehane grade assigned?

During the intubation attempt (laryngoscope view)

Cormack-Lehane grade I?

Full view of the glottis — entire vocal cords visible

Cormack-Lehane grade II?

Only part of the glottis visible (IIa partial cords — IIb arytenoids only)

Cormack-Lehane grade III?

Only the epiglottis visible — no glottis

Cormack-Lehane grade IV?

Neither glottis nor epiglottis visible — only soft palate

What are the five types of anesthesia?

General, Neuraxial, Regional, Moderate sedation or MAC, Local

What are the types of neuraxial anesthesia?

Spinal, Epidural, Caudal

What are the phases of general anesthesia?

Induction, Maintenance, Emergence, Recovery

When is the airway secured in general anesthesia?

After induction

What are the goals of the maintenance phase?

Unconsciousness, Amnesia, Immobility, Analgesia

What happens during emergence?

Discontinue anesthetic agent, Reverse neuromuscular blockade, Give antiemetics

What are the extubation criteria?

Awake, Hemodynamic stability, NMBA reversed, Vital capacity over 15 mL per kg, Tidal volume over 6 mL per kg, Negative inspiratory pressure over 20 mmHg, RR under 30, O2 sat over 93%

Where does postanesthesia recovery usually occur?

PACU (post-anesthesia care unit)

Who determines discharge from the PACU?

A physician (an RN may serve in this role if no physician)

Mainstay of intra- and postop pain control?

Opioids

Why is postop pain management shifting toward multimodal relief?

The opioid epidemic

Extra items to check in pre-anesthesia eval if neuraxial anesthesia is considered?

Local or systemic infection, Spinal abnormalities, Neurological disease, Hypovolemia, Intracranial lesions

Risks of neuraxial anesthesia?

Nerve damage or compression, Hematoma, Post-dural puncture headache, Infection, Nausea and vomiting, Hypotension, Back pain

Where is spinal anesthetic injected?

Subarachnoid space once CSF is obtained

Where is epidural anesthetic infused (and is CSF seen)?

Epidural space — CSF should NOT be seen

Benefits of a single-shot SPINAL?

Reliability, Fast block onset, Easy to perform, Small local anesthetic dose

Drawbacks of a single-shot SPINAL?

Finite duration, Block cannot be extended, Dura is punctured

Benefits of a continuous EPIDURAL?

Can extend duration and extent of block, Gradual block onset, Useful for postop pain control

Drawbacks of a continuous EPIDURAL?

Slow block onset, Larger local anesthetic dose, High headache incidence if dura punctured, More frequent block asymmetry

What is regional anesthesia also known as?

Peripheral nerve blocks

When is regional anesthesia often chosen over neuraxial?

Patient has a coagulopathy

Where is hematoma risk a concern with regional blocks?

Areas where compression is difficult (neck and non-compressible areas)

How are peripheral nerve blocks guided?

Ultrasound, Nerve stimulator

Nerve stimulator technique: needle is positioned until maximum twitch at what current?

0.5 mA

In MAC who is in charge of the anesthesia?

The anesthesia provider alone — a separate provider does the procedure

What sedation range does MAC cover?

Minimal to deep — never unconsciousness

How is the airway managed in MAC?

Patient protects own airway and retains reflexes — no intubation

What % of cases are MAC (with or without a peripheral block)?

30-40%

Key difference of moderate sedation vs MAC?

The same provider gives the sedation AND performs the procedure

Why is 'conscious sedation' an incorrect term?

Moderate and deep sedation patients are not conscious

Common uses of moderate sedation?

ED fracture reduction, Peds suture repair, Minor procedures

Sedation level: responds NORMALLY to verbal commands with airway and ventilation unaffected?

Minimal sedation (anxiolysis)

Sedation level: responds purposefully to verbal or light tactile stimuli with no airway intervention needed?

Moderate sedation

Sedation level: responds purposefully only to repeated or painful stimuli and may need airway help?

Deep sedation

Sedation level: unarousable even to pain and often needs airway support or PPV?

General anesthesia

A provider giving moderate sedation must be able to rescue a patient from which level?

Deep sedation (one level deeper than intended)

Airway interventions that may be needed in deep sedation?

Jaw thrust, Bag valve mask

What builds up in malignant hyperthermia?

Calcium with sustained muscle contraction, CO2, Lactate, Heat

Treatment of malignant hyperthermia?

Dantrolene

Which technique carries higher risk of accidental awareness during general anesthesia?

IV anesthesia alone (vs IV plus inhalation)

Most common cause of postop vision loss?

Corneal abrasion

Opioid reversal agent?

Naloxone

Neuromuscular blockade reversal agent?

Sugammadex

Neurologic complications of general anesthesia?

Stroke, Delirium, Cognitive dysfunction

Why is a ventilator needed during general anesthesia?

Gas exchange cannot be spontaneously maintained

Nine causes of pulmonary failure in the surgical patient?

Shock trauma and sepsis, Deranged respiratory mechanics, Atelectasis, Aspiration, Pulmonary contusion, Pneumonia, Pulmonary embolism, Cardiogenic pulmonary edema, Neurogenic pulmonary edema (rare)

ABG in HYPOXEMIC (type 1) respiratory failure?

PaO2 under 60 mmHg with normal or low PaCO2 and normal to alkalotic pH

Hypoxemic respiratory failure (failure to oxygenate) — examples?

Pneumonia, ARDS, Pulmonary edema

ABG in HYPERCAPNIC (type 2) respiratory failure?

PaCO2 over 45 mmHg and pH under 7.35 with normal PaO2

Hypercapnic respiratory failure (failure to ventilate) — causes?

Hypoventilation, Increased CO2 production, COPD, CNS depression, Neuromuscular issue (meds or disease)

A-a gradient in hypoxemic respiratory failure?

Widened

A-a gradient in PURE hypoventilation?

Normal

ABG pattern of respiratory acidosis?

pH under 7.4 with pCO2 over 40 mmHg

ABG pattern of respiratory alkalosis?

pH over 7.4 with pCO2 under 40 mmHg

Four methods of tracheal intubation?

Via the mouth, Via the nose, Cricothyroidotomy, Tracheostomy

When is cricothyroidotomy used?

Only in emergencies

Ventilator mode: ALL breaths supported for maximum rest of respiratory muscles?

Assist control (AC)

Ventilator mode: only machine breaths supported (historically used to wean)?

SIMV

Ventilator mode: every breath patient-triggered with pressure during inspiration (weaning and SBTs)?

Pressure support ventilation (PSV)

Which mode guarantees minute volume but risks barotrauma from high peak pressures?

Volume-controlled ventilation (VCV)

Which mode has lower barotrauma risk but tidal volume that varies with lung compliance?

Pressure-controlled ventilation (PCV)

How is minute volume calculated?

Tidal volume x respiratory rate

Components of a lung protective ventilation strategy?

Low TV 4-8 mL per kg predicted body weight, Moderate PEEP 5-10 cmH2O, Plateau pressure under 30 cmH2O, Lowest FiO2 to reach SpO2 88-92%

What are curved scissors called and what are they used for?

Metzenbaum — tissue manipulation and blunt dissection

What are straight scissors typically used for?

Cutting suture

What does the Bovie do?

Uses high-frequency current to cut tissue or coagulate vessels

What should be used alongside the Bovie?

Suction to remove smoke

Which forceps grab skin or tissue and are often used for sewing?

Adson forceps

Which forceps grab thicker tissue such as liver?

Russian forceps

Large vs small hemostats are called what?

Kelly clamp (large) and mosquito (small)

Which clamp passes suture around nerves or vessels to tag or tie?

Right angle clamp

Which clamp has interlocking teeth for soft tissue or fascia or tissue being excised?

Allis clamp

Which less-traumatic clamp holds delicate tissue like intestine or fallopian tubes or ureters?

Babcock clamp

Which heavy toothed clamp grasps fascia or tendon or bone?

Kocher clamp

Rigid curved suction tip with bulbous end?

Yankauer

Double-ended hand-held retractor with curved blades of different lengths?

Army-Navy retractor

Retractor with a flat curved blade for large amounts of tissue in deep incisions?

Richardson retractor