The use of analgesics, sedative medications and muscle relaxants in icu

THE USE OF ANALGESICS, SEDATIVE MEDICATIONS AND MUSCLE RELAXANTS IN ICU

Why sedate a PATIENT?
· Improve patient tolerance of procedures, invasive monitors and unfamiliar environments
· Airway control
· Decrease the work of breathing
· Decrease oxygen demand
· Reduce anxiety and pain
Examples
· Procedures:
o Patient intubation
o Bone marrow aspiration
o Minor surgical procedures
· Decrease agitation while on mechanical ventilation
· Facilitate air exchange in severe asthma
· Decrease oxygen demand in septic shock
Analgesia/Sedation Myths and Concerns
· ICU patient feel pain/anxiety more others
· Respiratory depression
· Hemodynamic compromise
Addiction
· A common fear voiced by every body
· Less common in hospitalized patients than in the general population
· Includes a psychological “need” or craving along with physical withdrawal symptoms if medication is discontinued
Tolerance
· The same dose of medication no longer has the same effect as when first started
· More commonly occurs in patients on long term continuous infusions of sedatives or analgesics rather than intermittent dosing
Dependence
· Removing medication results in withdrawal symptoms
· To avoid withdrawal, may need to wean sedative or analgesic when patient has been on the medication for 1 week or more
What is sedation?
drug that calms a patient down, easing agitation and permitting sleep. Sedatives generally work by modulating signals within the central nervous system. These sedatives can dangerously depress important signals needed to maintain heart and lung function if they are misused or accidentally combined, as in the case of combining prescription sedatives with alcohol. Most sedatives also have addictive potential. For these reasons, sedatives should be used under supervision, and only as
Continuum of Consciousness
· Level of Sedation Required
· In general, the younger the child and the lower their cognitive abilities, the more deeply sedated they will need to be to accomplish the same procedural goal
Conscious Sedation
· “ A medically controlled state of depressed consciousness that allows reflex ability to maintain a patent airway, and permits appropriate neurological responses to verbal stimuli.”
Deep Sedation
· “A medically controlled state of depressed consciousness or unconsciousness from which a patient is not easily aroused. It may be accompanied by a loss of protective reflexes and includes an inability to maintain a patent airway and respond appropriately to stimuli”.
Benzodiazepines
· Bind CNS GABA receptors
· Skeletal muscle relaxation
· Amnesia
o Antegrade and retrograde
· Anxiolysis
· Respiratory Depression
Midazolam (Versed)
Advantages:
o anxiolysis, sedation, motion control
o retrograde amnesia
o PO, IV, IM, IN, PR dosing routes
o onset 2-6 min after IV administration, 45-60 min duration
o available reversal agent
§ Flumazenil
Disadvantages
o No analgesia
o Paradoxical reactions
o More than additive risk of respiratory compromise when added to opiate
o Neonates: hypotension and seizures with rapid injection
o Peak serum level increased with itraconazole, erythromycin and clarithromycin
Barbiturates
· General CNS depressants
· Induction of anesthesia
· Hypnosis
· Sedation
· Respiratory depression
· Pentobarbital (Nembutal)
Advantages:
o Fairly safe
o Sedation, motion control, anxiolysis
o Short onset (3-5 min. given IV) and duration (15-45 min.)
o Alternative to chloral hydrate in older children
o PO, IV, IM, PR dosing routes
§ longer time to onset and longer duration with routes other than IV
o Pentobarbital
Disadvantages
o Enhances pain perception
o No reversal agent
· Chloral Hydrate
Advantages
o PO, PR dosing
§ initial 25-100 mg/kg
§ repeat after 30 min if need 25-50 mg/kg
o Anxiolysis, sedation, motion control
o Single dose toxicity is low
o Successful in younger patients (< 2-3 yrs)
o Many practitioners familiar with its use
Disadvantages
o 15-30 min to onset, lasts 1-2 hours
o Less successful in older children
o High doses can cause respiratory depression and dysrhythmias
o No pain control
o Not reversible
o Repetitive doses cause metabolites to accumulate with unknown toxicities
What is pain?
· Physical or mental suffering or distress
Two components of pain
· Physical stimulus
· Affective response
Analgesia
· “I can’t think of any other area in medicine in which such an extravagant concern for side effects so drastically limits treatment.”
What is Analgesia?
· “Relief of the perception of pain without intentional production of a sedated state. Altered mental status may be a secondary effect of medications administered for this purpose.”
Local analgesia for procedures
· EMLA Cream
o Apply to intact skin with occlusive dressing 30-60 min prior to procedure
· Buffered Lidocaine
o (1 ml bicarb/9 ml 1% lidocaine)
o Maximum dose lidocaine
§ 4.5 mg/kg without epinephrine
§ 7 mg/kg with epinephrine
Narcotic Analgesics
· Activate descending CNS tracts
· Sedation
· Analgesia
· Respiratory depression
· Moderate anxiolysis
Fentanyl
· Opioid
Advantages
o analgesia
o 100x more potent than morphine
o shorter duration than morphine
§ onset in 2-3 min, lasts 30-60 min
o less histamine release than morphine
o available reversal agent
§ naloxone
Disadvantages:
o no amnesia
o “Steel chest” or “rigid chest” phenomenon
§ more likely with large bolus dose
§ Treat with reversal of fentanyl or paralyzation
Morphine
· Opioid
Advantages
o Analgesia
o Less expensive than fentanyl
Disadvantages
o no amnesia, anxiolysis
o Histamine release - wheezing, hypotension
o Longer onset than other opioids
Ketamine
· Dissociative anesthetic
Advantages
o provides both analgesia and amnesia
o preserves upper airway tone and reflexes
o causes bronchodilatation
Disadvantages
o increases intracranial pressure
o laryngospasm
o hypersecretory response
o parents disturbed by blank stare
o emergence phenomenon/agitation
Relative contraindications
o head injury
o airway abnormalities
o procedures where posterior pharynx will be stimulated
o glaucoma, acute globe injury
o psychosis
o thyroid disorder
Pre-sedation
History
· General health
· Risk factors for sedation
· Current medications
· Allergies
· Previous anesthetic reactions
o patient / patient’s family
· Why is sedation required?
· Medications to be used
· ASA Physical Status
· Class I: Healthy patient
· Class II: Systemic disease
· Class III: Severe systemic disease
· Class IV: Severe systemic disease that is a constant threat to life
· Class V: Moribund / not expected to
§ survive without surgery
o In general, consider anesthesia or critical care involvement in patients that are ASA Class III or above and are not in the PICU
· Physical Examination
· Neurologic exam
· Airway exam
· Respiratory status
· Cardiovascular exam
· Personnel Responsibilities
· Evaluation
· Monitoring
· Familiarity with medications
· Anticipation of side effects
· Resuscitation
· Monitoring
General considerations
· Heart Rate, Respiratory Rate, Blood Pressure
· Continuous pulse oximetry
· ECG
· Perfusion
· Neurologic status
o State of consciousness
o Pupillary responses
· Discharge after Sedation for Short Procedure
· Ability to sit unassisted or flex their neck
· Verbal responses appropriate for age
· Protective airway reflexes intact
· Hemodynamic stability
· Spontaneous breathing/good oxygenation
· The patient has returned to their pre-sedation level of function
· Neuromuscular Blockade
· Achieves profound weakness of striated muscle without affecting the function of the cerebral cortex, smooth muscle or the myocardium.
Neuromuscular Blockade
· NEVER muscle relax a patient without assuring adequate sedation/analgesia beforehand.
· ALWAYS confirm the patient is easily hand-bag-ventilated prior to paralyzing
Monitoring Muscle Relaxants
· Progression of weakness:
§ small rapidly moving muscles of the fingers and eyes
§ muscles of the neck, limbs and trunk
§ muscles of respiration
· Recovery occurs in reverse order; the diaphragm recovers first
· Nerve stimulators:
· Stimulate nerve causing contraction of the corresponding muscle
· Train-of-four monitoring:
o 1 out of 4 twitches = 90% receptor blockade
· Fade
· Absent muscular response
· Clinical monitoring:
· Negative inspiratory force
· Flexion of neck muscles
· Infants:
· Hand grasp
· Grimace
· Flexion of hips
Muscle Relaxants
· Cause weakness followed by a flaccid paralysis
· Depolarizing muscle relaxants
o Stimulate motor nerve endings
· Non-depolarizing muscle relaxants
o Compete at receptor site
· All cause diaphragmatic paralysis
Muscle Relaxants Depolarizing Agents
· Imitate the affects of acetylcholine
· Initial fasciculations followed by paralysis
· Prevent repolarization of the muscle membrane
· Quick onset
Succinylcholine is the only depolarizing muscle relaxant in clinical use
adverse effects
· Profound bradycardia
· Hyperkalemia
· Increased intracranial and ocular pressure
· Hypersensitivity reactions
· Muscle pains
· Malignant hyperthermia
· Rhabdomyolysis
Contraindications
o Patients with paraplegia
o following strokes or burns
o muscular dystrophies, myotonia
o patients with a family history of malignant hyperthermia.
Muscle Relaxants Non-depolarizing Agents
· Competitively inhibit the binding of acetylcholine
· Most are steroid based
Pancuronium
· Non-depolarizing
· Tachycardia and hypertension due to muscarinic cholinergic blockage
· Renal elimination
Vecuronium
· Non-depolarizing
· No cardiovascular effects
· More expensive than pancuronium
· Hepatic elimination
Atracurium and Cisatracurium
· Non-depolarizing
· Short duration
o Best to use as continuous infusion
· Hofmann elimination
o Ideal agent in hepatorenal failure
Summary
· The hospital and especially the ICU are scary places for children. Therefore, the use of anxiolytics and analgesics to facilitate procedures and medical therapies is key to the proper care of the child.
· Safe use of sedatives requires knowledge of the medication used as well as close observation and monitoring of the child throughout the period of altered consciousness.
· When muscle relaxation is necessary, confirm that the child is adequately sedated and able to be ventilated manually prior to administering a paralyzing agent.