Risk Reduction in Sedation and Analgesia

Rowland P. Wu, MD Adapted from Glynne D. Stanley, MD

Overview

Complications occur because of:

Inappropriate patient selection

Unanticipated responses from patient or

equipment

Over-medication

Wrong patient/wrong site/wrong procedure

Strategies to reduce risk,‘patient selection’

Improve patient selection

ASA Classification

airway assessment and history

identify other factors e.g. pregnancy, obesity

Patient Selection

Important ‘baseline’ assessments are: actual or estimated weight vital signs including baseline oxygen

saturation cardiopulmonary status general neurological status previous adverse responses to medication

(not just allergy detection)_ ASA classification (Baseline airway evaluation)

ASA Classification ASA 1 Normal, healthy patient ASA 2Stable mild systemic disease ASA 3Severe systemic disease with functional

impairment ASA 4Severe disease, constant threat to life,

not necessarily to be improved by surgery ASA 5Moribund patient, not expected to survive

without surgery ASA 6Brain-dead donor Emergency (E)

Patient Selection

All patients should be carefully

evaluated by the MD. Some ASA Class

III, and most ASA Classes IV and V will

not be suitable for sedation

administered by non-anesthesiologists.

Mallampati classification

Airway Assessment

Mallampati classificationNeck extensionThyromental distance (?short neck)Interincisor distance (?poor mouth opening)Concurrent obesity(History of airway problems)

Letters and bracelets

Patient Selection

Anesthesia consultation should also be considered under the following circumstances: patient has limited neck motion or cervical

instability patient has abnormal craniofacial anatomy patient is morbidly obese patient has a history of sleep apnea pregnant patients patient has not been NPO

Strategies to reduce risk,‘unanticipated events’

Have available and be familiar with essential pieces of equipment basic interpretation of ECG understand pulse oximetry and know the

limitations of use capnography reliable oxygen source, equipment for

positive pressure ventilation know how to quickly and reliably get help

Ideal Patient Positioning

Obstructed Airway

Oral Airway

Nasal Airway

Mask Ventilation

EtCO2 Apparatus

EtCO2 Tracing

Unanticipated events

Cardiac instability/dysrhythmia

Respiratory depression and/or airway

obstruction

Neurological ‘disconnection’

Equipment malfunction

Unanticipated cardiovascular events

Cardiovascular instability Hypotension Tachycardia PVC’s atrial arrhythmias ventricular

arrhythmias cardiac arrest!

Possible causes hypovolemia allergic reaction overmedication hypoxemia ischemia hypercarbia bleeding

Unanticipated respiratory events

Respiratory complications depression

airway

obstruction

bronchospasm

Possible causes overmedication

relativeabsolute

patient position ‘foreign material’ allergic reaction

Unanticipated neurological events

Neurological ‘Disconnection’ drowsiness unresponsiveness uncooperative combative disinhibition

Possible causes overmedication Hypoxemia hypercarbia cerebral ischemia

hypoxemiacerebral

hypoperfusion undermedication?

Unexpected events:The catastrophe!

Call for help/Code BlueDiscontinue sedative therapy,

infusions /transfusions etcBegin BCLS/ACLS if appropriateprepare emergency equipment, drugstry to anticipate resuscitation needs

Equipment problems:E.C.G.

Problems No trace/loss of

trace

Poor quality

Intermittent trace

Interference

Possible causes ASYSTOLE!! loose leads incorrect placement dry electrodes! greasy skin respiratory variation electrical interference

Equipment problems:Non-invasive BP

Problems no reading repetitive cycling very low/high BP ??Arterial line

Possible causes: HYPOTENSION! HYPERTENSION! cuff leak wrong size cuff arrhythmia e.g. AF tubing kinked patient/MD movement

Equipment problems:Pulse oximetry

Problems: no reading

low reading

intermittent trace

frequent alarm

Possible causes no pulse! hypoxemia! decreased perfusion dye injection electrical interference inappropriate sat/pulse

settings incident light/nail polish

Equipment problems:Pulse oximetry

REMEMBER! Oximetry does not measure respiration there may be a lag phase, depending on

probe site

as with all the equipment:if it isn’t working at the beginning it will

not suddenly get better, it is likely to let you down when you need it most.

Strategies to reduce risk,‘over-sedation’

Have an understanding of the pharmacology involved in conscious sedation Titrate drugs carefully to patient weight but

especially to effect. Have appropriate reversal agents readily

available and know how to use them Know where other emergency drugs can

be found

Commonly Used Medications

Midazolam intravenous/oral/intramuscular/intranasal Initial dose 0.5-2mg iv over 2 min Onset 1minute, peak 3-5 mins Wait full 2 mins between doses with 0.5-

1mg increments Duration 1-2 hours

Commonly Used Medications

Valium Initial dose 2-5 mg iv Onset 1-5 mins Wait full 5 mins between doses with 1 mg

increments Duration 3-4 hours

Commonly Used Medications

FentanylOnset 1-3 min; peak-effect at 3-5

minutes Initial dose 25-50 mcg iv titrated in 25mcg doseslow dose drug is short actingDuration of effect 30-60 mins

Commonly Used Medications

MorphineOnset 1-6 minInitial dose 2-5 mg iv titrated in 2 mg doses but wait 3-5 mins

between dosesDuration of effect 3-5 hours

Commonly Used Medications

MeperidineInitial dose 25-50 mg ivOnset 2-8 mins, peak 20 minsMild vagolytic and antispasmodicNormeperidine is pro-convulsantDose titration 12.5-25mg; Duration 2-

3hrsInteraction with MAOIs

Overmedication

Why does overmedication occur? Excessive dose Overly sensitive patient,

concurrent medications or disease states Inadequate time for effect before more

drug administered Abnormal response such as hyperactivity

leading to more medication

Overmedication

What problems does overmedication cause? Airway obstruction Hypoxemia and hypercarbia Loss of protective reflexes Loss of contact with the caregiver Hemodynamic instability Interferes with the procedure

Overmedication

How may overmedication be managed? stop medicating! open airway and stimulate to breathe ensure adequate oxygen supply call for help early, especially if

hemodynamic instability consider reversal of medication have suction immediately available

Overmedication

How may medication be reversed? Opiates and benzodiazepines are the only

drugs with specific antagonists:

REMEMBER: once reversal agents are

used this MUST lead to a longer period of

post-procedure monitoring.

Reversal Agents

NALOXONE, 40mcg - 400mcg slow I.V.Onset 1-3 minutes, duration 45 minuteswill reverse analgesiamay cause pulmonary edemabeware withdrawal effects if long term narcotic usemay need repeating or infusion

Reversal Agents

FLUMAZENIL, 0.1mg - 0.2 mg I.V. for partial reversal0.4mg - 1.0mg I.V. for complete reversalOnset 1-2 minutes, duration 45 minutesmay precipitate withdrawal seizurenot to be used routinelyhalf life of benzodiazepine may be long so

flumazenil may need to be repeated

Summary Choose your patients carefully.

Check and understand your equipment

Use medication judiciously, you can’t take it out but you can always give more!

Have reversal agents available but remember basic airway techniques.

Be vigilant and prepare for the unexpected.