Sedation in the ICU Mairi Mascarenhas Clinical Educator

Sedation in the ICU Mairi Mascarenhas Clinical Educator ICU

Introduction Sedation is an induced state of reduced consciousness to which verbal contact with the patient may be maintained. It is used to reduce anxiety and distress, and to facilitate compliance with invasive procedures such as mechanical ventilation. Before sedation is initiated, the cause of distress should be identified – common causes in critically ill patients include anxiety, pain, delirium, dyspnoea and neuromuscular paralysis. These aetiologies may occur separately or in combination.

Pain, Agitation and Delirium (PAD) Guidelines

The PAD triad

Avoid deep sedation or over sedation Deep sedation should only be used when the benefits are likely to outweigh the risks • Patients receiving NMBA’s. • Acute cerebral injury: for control of intracranial pressure. • Patients that are difficult to ventilate • Refractory status epilepticus.

Under-sedation • Mechanical ventilation asynchrony • Stress response with increased myocardial oxygen consumption • Cardiovascular instability • Failure to comply with treatment • Unplanned extubation or removal of lines and monitoring devices by the patient

Assess Treat Prevent • • Assess sedation/agitation score every hour Agitated → RASS +1 to +4 Deeply sedated → RASS -4 to -5 Avoid deep sedation unless clinically contraindicated • Treat pain 1 st then sedate • Goal → patient purposefully follows commands without agitation • Consider daily sedation interruption/SBT • Consider dexmedetomidine • Communicate with patients + explain procedures

Touc h Voice Observation Monitoring level of sedation

Sedation – goals of care Stop sedation → lighten patient → change to PS → extubate Sedation interruption doesn’t always mean that the patient will be extubated – the important point is that sedation interruption has been attempted

Benefits of sedation interruption Avoid excess sedation • Allows neurological function to be assessed • Assists to reduce the need for diagnostic testing CT/MRI • Allows sedation dose to be optimised to an ideal level • Prevents drug accumulation • Reduces inotrope/vasopressor requirements • Cardiovascular instability is reduced – bradyarrhythmias • Reduces risk of complications e. g. muscle wastage, debility, critical illness myopathy. • Reduces time on ventilator, risk of VAP and LOS in ICU

Daily sedation interruption • Hold sedation until patient awake and then restart at 50% of the prior dose. • “Awake” defined as any of the following - Opens eyes in response to voice - Uses eyes to follow investigator on request - Squeeze hand on request - Stick out tongue on request

Procedure for stopping sedation If there are no contra-indications 1. Stop sedation at 0800 hrs or as otherwise directed by medical staff. 2. Pain control may be an issue. If patient scoring positive for pain → maintain opioid infusion 3. Continue to hold sedation until patient obeys commands and RASS improves e. g. -1 4. If after 1 hour the RASS doesn’t improve or remains ≥ 3 and the patient is still receiving an opioid infusion → discuss with medical staff regarding appropriateness for stopping opioid infusion 5. Wait a minimum of 15 minutes before changing ventilator settings e. g. Observe for spontaneous breathing → change to PS mode 6. If patient becomes difficult to manage i. e. RASS + 2, +3 or +4 resedate patient with rescue bolus of propofol (increments of 20 to 30 mg) and inform medical staff.

Adhere to the sedation interruption protocol Whenever sedation needs to be restarted → restart at ½ the previous infusion rate as per protocol

Failure criteria for sedation interruption • Sustained anxiety, agitation or pain. • Respiratory rate > 35 per minute for ≥ 5 minutes. • Oxygen saturation ≤ 88% for ≥ 5 minutes. • Acute cardiac dysrhythmia. • ≥ 2 signs of respiratory distress, including tachycardia, bradycardia, accessory muscle use, abdominal paradox, diaphoresis or marked pyrexia.

Sedatives used in ICU Treat • Propofol • Alpha 2 agonists: dexmedetomidine • Benzodiazepines: midazolam (infrequently used) • Analagesics i. e. opioid infusions are often combined

Propofol Treat • IV anaesthetic • Frequently used on ICU and given as an infusion • Insoluble in water and prepared in a lipid emulsion, calorie content 1 calorie per ml • Available in 1% and 2% preparations • Rapid onset of action i. e. 30 seconds • Single dose will last 5 to 10 minutes • No change in pharmacokinetics with hepatic or renal dysfunction

Adverse effects of propofol • Respiratory depression Treat • Suppression of laryngeal reflexes – caution is required in patients with unprotected airways. • Cardiovascular depression • Inotropic/vasopressor support often necessary • Hypertriglyceridaemia • No analgesic properties • Pain if given peripherally

Midazolam Treat • Benzodiazepine • Produces sedation, amnesia, muscle relaxation and has anti-epileptic effects • Rapid onset of action i. e. 30 secs to 2 minutes • Minimal accumulation occurs with infusions <24 hrs but can occur thereafter • Metabolism can be affected by hepatic function/blood flow and other drugs – wide variability in half-life • Not frequently used but may have a role in alcohol and drug withdrawal.

Adverse effects of midazolam • Hypotension • Delirium • Accumulation when given by IV infusion especially > 24 hrs • Slow to wear off • Liver and renal impairment can prolong sedative effect • No analgesic properties Treat

Dexmedetomidine and Clonidine Treat • Alpha-2 agonists • CNS actions include sedation, anxiolysis and analgesia but without reduced respiratory depression “awake sedation” • Dexmedetmodine has a higher affinity to alpha-2 receptor than clonidine making its sedative effects more prominent • Dexmedetomidine only licensed for patients requiring RASS no deeper than -3 • Sedation is unique – patients can be roused more readily. Can extubate patient without stopping sedation. Doesn’t produce delirium. • Dexmedetomidine decreases ventilation compared to midazolam (but not to propofol)

Adverse effects of Dexmedetomidine • Bradycardia most common Treat • Hypotension • Rebound hypertension on abrupt withdrawal • Dose reduction may be needed in elderly/frail and hepatic impairment • Expensive – Consultant only • Contraindications - advanced heart block unless paced, uncontrolled hypotension, acute cerebrovascular conditions

Dexmedetomidine infusion table Titrate infusion up or down every 10 minutes as per BP/HR response Infusion table: dexmedetomidine 8 micrograms/ml

Dexmedetomidine Treat • Patient aged 50 years • Weighs 80 kg • Starting dose is 7 mls/hr • Titrate dose up every 10 minutes where possible to maximum dose i. e. 14 mls/hr provided BP and HR are stable • The propofol infusion needs to be titrated ↓ and suggest doing this every 10 minutes