Sedation- Overview and Preoperative Assessment

workflow for sedation

1) pre-procedure assessment

2) IV started

3) monitors applied

4) pre-oxygenated with 100% O2

5) induction medications

6) maintenance medications

further steps for GA when pt can no longer protect their own airway- should always be prepared:

7) mask-ventilated, then given a neuromuscular blocker (e.g. succinylcholine)

8) laryngoscopy and intubation through the vocal cords (or LMA)

9) confirm the tube is in the right place

components of anesthesia- what are we trying to achieve?

-anxiolysis: relief of fear and anxiety; benzodiazepines, N2O, dexmedetomidine

-amnesia: no memory of the procedure; midazolam, propofol

-analgesia: blocking pain; local anesthetic, opioids, ketamine

-hypnosis: depression of consciousness; propofol, ketamine, inhaled anesthetics

5 ways to manage an anxious patient

drugs used in OMFS clinic- agent, class, what to remember

minimal, moderate, deep, GA sedation

level 1 of 4- minimal sedation (anxiolysis)

-responds normally to verbal commands

-cognitive function and coordination may be impaired

-airway, breathing, and cardiovascular function are not affected

level 2 of 4- moderate sedation (“conscious sedation”)

-often level of sedation in OMFS clinic

-drug-induced depression of consciousness

-responds purposefully to voice or light touch; reflex withdrawal from pain is NOT purposeful

-airway stays patent and spontaneous ventilation is adequate, without intervention

-cardiovascular function is usually maintained

level 3 of 4- deep sedation

-drug-induced depression of consciousness

-not easily roused; responds purposefully only to repeated or painful stimulation

-may need help keeping the airway open; breathing may be inadequate

-cardiovascular function is usually maintained

level 4 of 4- general anesthesia

-drug-induced loss of consciousness; unarousable, even by painful stimulation

-ability to maintain an airway is impaired

-positive-pressure ventilation is often required- depressed breathing or neuromuscular function

-cardiovascular function may be impaired

preoperative evaluation- consultation visit

-history, functional capacity, exam and airway, ASA class/testing, NPO and consent, day-of re-check

-stratify the risk: is this pt safe for office sedation, and at what depth?

-plan together: pt and surgeon agree on the anesthetic and procedure

-optimize: problems caught early can be fixed before surgery day

step 1- history

-medical, surgical, and anesthetic history

-medications: everything, including OTC drugs and herbal supplements

-social history: alcohol, recreational drugs, tobacco, vaping, marijuana (no universal protocol- think about increased airway reactivity risk (counsel pt to stop smoking before surgery, at minimum 2 days), sedation meds- association with requiring higher amount of anesthesia)

-allergies: know reaction, asked what happened, nausea after an opioid is a side effect (not an allergy)

-prior anesthesia: patient and family, slow recovery, nausea and vomiting, fever after anesthesia, difficult airway

-asthma, recent URI: how controlled, rescue inhaler use, ED visits, a recent URI may mean postponing 2-4 weeks

-snoring, sleep apnea: CPAP or BiPAP use, screen with STOP-BANG, flags obstruction and a difficult airway

conditions that change the plan

step 2- functional capacity

-can they climb 2 flights of stairs?

-1 MET (metabolic equivalent) = the oxygen you use sitting quietly at rest, about 3.5mL O2/kg/min; 4 METs = 4x that

-under 4 METs: self-care, eating and dressing, walking around the house or a block or two, dusting, washing dishes; not an office deep sedation or GA candidate

-4-10 METs: 2 flights of stairs or a hill, walking at 4mph, scrubbing floors, golf, dancing, doubles tennis

-over 10 METs: swimming, singles tennis, football, basketball, skiing

step 4- risk stratification

-ASA physical status classification

step 3- exam and airway

-anesthesia-focused physical exam:

-baseline vitals: bp, heart rate and rhythm, RR, SpO2 on room air, height, weight, BMI, heart and lung auscultation

-oral, head, and neck: intraoral hard and soft tissues, head and neck exam, veins for IV access

-airway: Mallampati class, neck circumference and mobility (neck extension needed for intubation), thyromental distance, retrognathia, incisal opening

-every finding (positive and negative) goes in the record

Mallampati score

-pt seated, mouth wide open, tongue out, no phonation

-the less you can see, the harder the airway is to rescue

-Class III-IV: think twice about office anesthesia

airway exam- BMI

-hard to mask-ventilate: facial hair, edentulism, short thick neck, high BMI, age over 55, snoring/OSA, Mallampati III-IV, limited jaw protrusion, neck circumference and neck radiation

-sternomental distance: under 12.5cm predicts a difficult intubation

-obese and pediatric pts have less functional residual capacity, so they desaturate faster

special populations

-children: history comes from the caregiver, expect laryngospasm- bradycardia is ominous, weigh them, size the equipment, precalculate emergency doses

-older adults: assess frailty, METs and mental status (delirium risk), start low & go slow, expect a longer recovery

-obese pts: difficult airway, less FRC, hard IV access, use opioids cautiously especially with sleep apnea

-pregnant pts: delay elective surgery, consult the prenatal care provider, many LAs are considered safe

step 4- testing, labs and ECG

-cardiac disease: ECG, especially for symptoms, a new arrhythmia or known disease that will change management

-diabetes: glucose and HbA1c, insulin dosage the night before and schedule as first pt of the day, be mindful of keeping NPO for long periods of time

-warfarin or liver disease: INR within 5 days, then recheck within 24hr of surgery

-lung disease: room-air SpO2

-liver or kidney disease: CMP and a consult

-pregnancy: ask every pt of childbearing age, no routine testing (AAOMS); test if history is uncertain, point-of-care urine hCG (offer minors a private test), positive test = postpone elective sedation

step 5- NPO

NPO for GLP-1 receptor agonists

step 5- consent

-risks, benefits, and alternatives

-name the level of anesthesia planned, and how moderate sedation, deep sedation, and general anesthesia differ

-anesthesia options confuse many pts

-answer the pt’s questions and concerns

-let the pt choose a different option, or talk it over with family

-confirm a responsible escort for surgery day

-many surgeons complete consent at the consultation visit

five keys to office risk stratification

-ASA class: I-II best, III with caution

-METs: at least 4 for deep sedation or GA

-mallampati: predicts a difficult airway

-BMI: both extremes add risk

-airway access: can you rescue it if it’s lost

-anatomy: can I give this pt oxygen if they stop breathing?

-reserve: how long can they tolerate apnea before they decompensate?

room setup

-MSMAIDS

step 6- day of surgery, immediate preoperative reassessment

-before the pt arrives: requested labs, imaging and consults in the chart, reviewed and documented

-when the pt arrives: brief problem-focused re-check, confirm NPO status, escort and other instructions

-something changed? deal with it now (i.e. asthmatic- auscultate the lungs, have them use their inhaler; child with a new URI- consider postponing elective surgery; fasting diabetic- check a fingerstick glucose)

-then time-out: correct pt, correct procedure

OMS team model

-at least 3 people in the room

-1: surgeon (team leader), ACLS certified

-2: monitor, sole job is the pt- holds the head for a patent airway, watches the monitors, reports any change, BLS

-3: surgical assistant, suctions and assists with surgery, at minimum a dental assistant with BLS

-every team member is empowered to speak up

monitoring- what goes on every sedated pt

-ECG (continuous)

-blood pressure

-pulse oximetry, on the arm opposite the BP cuff

-end-tidal CO2 (capnography)

-temperature, when clinically significant changs are intended, anticipated, or suspected

-document baseline vitals bp, hr, ECG, SpO2 before the first dose

-a trained person whose job is to watch them

documentation- the sedation and anesthesia record

-before: ASA class, mallampati, NPO status, weight/height/BMI, premedication, equipment check, time-out

-during: every drug, dose and time (including LA, fluids, and O2), vitals charted every 5 minutes

-anesthesia and surgery start and stop

-setup: monitors used, IV gauge and site, airway adjunct- nasal cannula to ET tube, patient position

recovery- discharge criteria

rescue armamentarium

important sedation reminder

-titrate slowly

-it’s a continuum: levels aren’t discrete, and they aren’t always drug- or dose-specific

-plan one level deeper- be able to rescue the pt from the level past the one you intended

-assess before you sedate: history, METs, airway, ASA class, NPO; then re-check on the day