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 2 Stable mild systemic disease ASA 3 Severe systemic disease with functional impairment ASA 4 Severe disease, constant threat to life, not necessarily to be improved by surgery ASA 5 Moribund patient, not expected to survive without surgery ASA 6 Brain-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 classification Neck extension Thyromental 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 relative absolute patient position ‘foreign material’ allergic reaction

Unanticipated neurological events Possible causes overmedication Hypoxemia hypercarbia cerebral ischemia hypoxemia cerebral hypoperfusion undermedication? Neurological ‘Disconnection’ drowsiness unresponsiveness uncooperative combative disinhibition

Unexpected events: The catastrophe! Call for help/Code Blue Discontinue sedative therapy, infusions /transfusions etc Begin BCLS/ACLS if appropriate prepare emergency equipment, drugs try to anticipate resuscitation needs

Equipment problems: E.C.G. 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 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 Possible causes no pulse! hypoxemia! decreased perfusion dye injection electrical interference inappropriate sat/pulse settings incident light/nail polish Problems: no reading low reading intermittent trace frequent alarm

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 Fentanyl Onset 1-3 min; peak-effect at 3-5 minutes Initial dose 25-50 mcg iv titrated in 25mcg doses low dose drug is short acting Duration of effect 30-60 mins

Commonly Used Medications Morphine Onset 1-6 min Initial dose 2-5 mg iv titrated in 2 mg doses but wait 3-5 mins between doses Duration of effect 3-5 hours

Commonly Used Medications Meperidine Initial dose 25-50 mg iv Onset 2-8 mins, peak 20 mins Mild vagolytic and antispasmodic Normeperidine is pro-convulsant Dose titration 12.5-25mg; Duration 2-3hrs Interaction 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 minutes will reverse analgesia may cause pulmonary edema beware withdrawal effects if long term narcotic use may need repeating or infusion

Reversal Agents FLUMAZENIL, 0.1mg - 0.2 mg I.V. for partial reversal 0.4mg - 1.0mg I.V. for complete reversal Onset 1-2 minutes, duration 45 minutes may precipitate withdrawal seizure not to be used routinely half 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.