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.