Fundamentals of Critical Care
Transcript of Fundamentals of Critical Care
Fundamentals of Critical Care
Supporting pharmacists new to the critical care setting during the
COVID19 pandemic
Updated March 2020
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Plan
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Introduction
Sedation and muscle relaxants
Vasoactives
GI
Fluids
Haemofilter
General house keeping
You already know the basics!
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Encompasses all other topics
Interpreting Lab results
Managing infection
Respiratory Disease
Care of surgical patients/
elderly/renal
Critical Care
The term critical care covers ‘ICU ’ (level 3) and ‘HDU’ (level 2)
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Level 3Staffed with
1 nurse per patient
requiring 2 or more different organ support orrespiratory failure requiring
mechanical ventilation.
Level 2
1 nurse to 2 patients, receiving single organ support (e.g. post-surgical or on low dose
vasopressors such as noradrenaline)
Level 1Normal ward care – no organ support (may require IV or
oxygen by face mask)
Aims of Critical Care
• To preserve life and prevent, reverse or minimise damage to vital organs
• To optimise cardiovascularand respiratory function to maximise oxygen delivery to tissues
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Monitoring in ICU
SIMPLE MORE COMPLEX
Respiratory rate Arterial line
Heart rate CVP line on central line
Blood pressure Oesophageal doppler
Temperature ECHO
Oxygen saturations ECG
Urine output
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Lines
Central Line
➔ Inserted into a large vein in the patient
➔ Neck (jugular) vein➔ subclavian vein (the vein lying
beneath the collar bone)➔ femoral vein
(large vein in the groin)
Branches off into smaller lines (or lumens). This provides ports whereintravenous fluids, drugs and monitoringcan be attached. Each lumen can be treated as separate line when considering compatibilities
Arterial line
➔ Inserted into an artery (usually in the wrist or the groin)
It has 2 functions:
1. It is attached to a system to measure BP etc
2. It is set up to enable easy, frequent arterial blood sampling, with no stress to the patient.
There is a flush bag connected to the transducer setup is encased in a pressure cuff that constantly squeezes the bag. This allows the fluid from the flush bag to flow into the artery. This is important because without pressure from the flush, the arterial line tubing would fill with blood.
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Ventilation
• Lots of different modes
• The higher the % oxygenused can estimate how sick patient is
• More invasive modes may require more sedation to tolerate
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Methods of ventilation
Endotracheal tube (ETT)• Placed in through the mouth and
into the trachea• Can be very uncomfortable and the
patient is sedated to tolerate it
A tracheostomy
• An opening is made into the trachea allowing for ventilator support with minimal or no sedation.
• Useful if patient has excessive secretions during weaning
• Mouth care is easier
Disadvantages
• Bleeding• Communication
difficulties
Both methods can cause ventilator associated pneumonia
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Sedation
• How sedated does a patient need to be?
– Awake? Unrousable? Aware?
• Beneficial practices to assess sedation
– Sedation breaks
– Sedation scoring
Example – Richmond Agitation Scale (RASS)
Patient sedated to a prescribed score
Score Description
+4 Combative, overtly combative or violent, immediate danger to staff.
+3 Very agitated, pulls on or removes tubes or catheters or is aggressive.
+2 Agitated, frequent non-purposeful movement or ventilator dyssynchrony.
+1 Restless, anxious or apprehensive but movements not aggressive or vigorous.
0 Alert and calm.
-1 Drowsy, but sustains more than 10 seconds awake, with eye opening in response to verbal command.
-2 Light sedation: Awakens briefly (less than 10 seconds) with eye contact to verbal command.
-3 Moderate sedation: Any movement, except eye contact, in response to command.
-4 Deep sedation: No response to voice, but any movement to physical stimulation
-5 Unarousable: No response to voice or physical stimulation
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Indications for sedation
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Reduce anxiety and distress
Alleviation of pain
Ventilation
Primary Therapy(reduce intracranial pressure, refractory status epilepticus)
During neuromuscular blockade
Sedation and analgesia
• Anaesthetic (propofol, midazolam etc)
• Analgesia (alfentanil, remifentanil, fentanyl, morphine etc)
• Most units have their standard and may use different if patient has allergies or contraindications
• May add another in if patient is difficult to sedate e.g. propofol + alfentanil + midazolam
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Summary of Sedation Problems
• Accumulation can be a problem (delaying weaning and increasing complications)
• Some have detrimental effects on circulation, increasing inotrope (e.g. noradrenaline) requirement
• Tolerance and withdrawal
• Does not provide REM sleep
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Propofol
• Intravenous anaesthetic. Mode of action unclear, potentiates glycine and GABA
• Dose = 1-4mg/kg/hr (practically 0-20mL/hr 1%) – max dose 4mg/Kg/hr
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Advantages:– Short duration of action (starts and stops quickly)
• t1/2 is approximately 10 – 70 minutes– Good for assessing the patient e.g. head injury– Anti-tussive/reduces bronchospasm
Propofol
• Disadvantageso Causes hypotension
o High lipid load (1kcal/mL)
o No analgesic effects
o Tolerance
o Peanut allergy
o Propofol infusion syndrome
Propofol Infusion Syndrome Clinical features:
o Cardiomyopathy with acute cardiac failure.
o Metabolic acidosis, ↑↑K+
o Renal Failureo Hepatomegalyo Inhibition of free fatty acid entry into
mitochondria → failure of its metabolism.
KEEP DOSE BELOW 4mg/kg/hr
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Midazolam
Advantages➢ Bolus rapid onset➢ Ease of administration➢ Stable in sodium chloride
and glucose
Disadvantages➢ No specific analgesic properties
➢ Prolonged duration of action in both hepatic and renal impairment
➢ Accumulation
➢ Dependence
• Half life 1-4 hours
• Metabolism - Liver
• 1,4 hydroxy midazolam- active metabolite cleared by kidney
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Other sedatives
Ketamine• Blocks NMDA- receptors
• Lack of respiratory and cardiovascular depression
• Useful for anaesthesia in asthmatic patients
• Sympathetic agonist (↑ BP ↑HR ↑CO)
• Limitations: hallucinations, deliriumduring withdrawal
• Suggested dose range 1.0-2.5mg/kg/h
• Elimination half life 2-3 hours, renal excretion
Clonidine/Dexmedetomidine
• α2-adrenoreceptor agonists
• They are particularly useful if agitation is a feature or after withdrawal of benzodiazepines or opioids.
• Dex- shorter acting and easy to titrate
• Clonidine- enteral available
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Alfentanil
• Synthetic opioid
• Peak effect after 2-3 mins
• Half-life 15-137 mins
• Not affected by renaldysfunction
• Metabolised by the liver
Advantages✔ Easy to administer
✔ Does not cause histamine release
✔ Less vasodilatation than with morphine
Very potent! Depending on patient metabolism 1mg of alfentanil is equivalent to 10-20mg of morphine
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Disadvantages⮚ Potent respiratory depressant
Morphine• Half life 1-6 hours
Metabolism
• Morphine undergoes conjugation with glucuronide in the liver
• Metabolite is 40 times more potent, this is then excreted in urine and will accumulate in renal impairment
Advantages✔Excellent analgesic
✔ Inexpensive
✔Compatible with a range of drugs
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Disadvantages⮚ Poor amnesic properties
⮚ Slow onset of action due to its slow distribution and relative lipid insolubility
Fentanyl
• Synthetic opioid
• 50-100x more potent than morphine
• Peak effect 30 mins
• Lipophilic - Short duration when given via bolus but long when given by continuous infusion
• Lack of emetic effect
• 80% plasma bound
• Hepatically metabolised to inactive and non toxic compounds, 8% urinary excretion
• Renal impairment - increase in half-life
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Remifentanil• Very potent
• Rapid onset of less than 1 min
• Predictable offset of less than 10 mins
• Metabolised by non-specific blood and tissue esterases
• Less interpatient pharmacokinetic variability
• No bolus
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Muscle Relaxants
▪ Routine paralysis is no longer recommended.
▪ Only indications
▪ Critical gas exchange- LIKE COVID 19 Patient
▪ Control of ICP
▪ Multiple trauma
▪ Must make sure well sedated
Atracurium• Hoffman elimination, Histamine
release
Rocuronium• Active metabolite of vecuronium
• Renally excreted, Rapid onset of action
• Less histamine
Cisatracurium• Cis-isomer of atracurium
• Minimal histamine release
• Less laudanosine production
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Prone Position• Patient turns onto front or semi-
prone “swimming position”
• Used in resp failure and severe hypoxia despite optimisation of sedation, ventilation, neuromuscular blockade and fluid balance.
• More common in COVID patients
Pharmaceutical Implications
Eye, lip and skin care
May need longer infusion lines
Absorption of feed more difficult
More at risk of transient arrythmia-ensure electrolytes within range
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Vasoactive agents
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VASOPRESSOR – a drug which causes
contraction of muscular tissue in capillaries and
arteries
INOTROPE - a drug that affects myocardial
contractility positive / negative
CHRONOTROPE - a drug that affects the
myocardial contractionrate
all have short half-lives ~ 2minutes and must be
administered by infusion for prolonged effect
stable plasma concentrations are
achieved within 10-15 minutes
Haemodynamic values
● Cardiac output (CO): amount of blood
ejected from the heart into systemic
circulation each minute
○ *Normal = 4-8 L/min
● Cardiac index (CI): CO adjusted for BSA
○ *Normal = 2.5-4 L/min
● Stroke volume (SV): amount of blood
ejected from the heart into systemic
circulation with each contraction
○ SV = CO (mls) / HR
○ *Normal = 60-130 / beat
• MAP= CO x SVR
• CO= HR x SV
• SVR=Systemic vascular resistance
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Summary of ActionsReceptor Site Effect Drug with predominate
agonist effect
Adrenaline receptor affinity (Dose dependant)
α1 Arterial Vasculature
Vasoconstriction NoradrenalineMetaraminol, Phenylephrine
++
V1 Vascular smooth muscle
Vasoconstriction VasopressinTerlipressin
β1 Heart ↑myocardial contractility↑heart rate
Dobutamine +++
β2 Lungs, blood vessels
BronchodilationVasodilation
++
Phosphodiesterase III inhibitors in cardiac and smooth muscle
Mycocardial diastolic relaxation
MilrinoneEnoximone
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Drug delivery - Gut
• If the gut works use it!
– For both nutrition and drugs
• Post GI surgery may be nil by mouth
• Non-ventilated patients may be fine to swallow tablets normally
• Ventilated patients will normally have an NG tube
• Ask whether the patient is absorbing feed
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Drugs via NG tube
• Avoid MR/EC preparation– Can change to ‘normal release’ if possible &
amend frequency
• Consider safety for staff
– finasteride
• Liquids – watch bioavailability
• Patches
• Alternative drugs for same condition/same class
– Often anaesthetists looking after patients that aren’t familiar with every day drugs
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Gastric stasis
• Some patients in shock/sepsis may have gastric stasis.
• Also called ileus• Opiates also slow peristalsis• Won’t absorb feed• Drug absorption likely to be impaired• Treat with prokinetics
– low dose erythromycin IV 125mg-250mg BD
– Metoclopramide IV 10mg TDS
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Blood Glucose
• In critically ill patients there is impaired hepatocyte response to insulin which correlates with increased risk of death
• Hypoglycaemia associated with worse outcomes.
• Hyperglycaemia (due to insulin resistance) is common in the critically ill patient (inc. non diabetics)
• All patients should have HbA1C checked on admission
• REVIEW all oral agents- check policy & resource section of www.saferinsulin.org
Consider implications of poor SC absorption
Further reading www.saferinsulin.org
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4 phases of IV Fluid Therapy
Hoste et al 2014
IV Fluid Therapy
Fluid overload big problem in COVID
patients
Only give small boluses in
resuscitation phase
Consider all COVID patients fluid
restricted
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(CALORIES HELP TO DEAL WITH ELECTROLYTES NORMALLY)
DAILY REQUIREMENTS (GIFTASUP Guidance)
Water 25-35 ml/kg (30)
Sodium Approx. 1 mmol/kg
Potassium Approx. 1 mmol/kg
Calories Minimum 400 calories (i.e. 100g glucose)
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Methods of RRT
⚫Haemofiltration (Usually continuous venous-venousso called CVVH)
⚫MOST COMMON FORM ⚫Dialysis⚪ Diffusion
⚪ Rarely ever (never) used on its own
⚪ Sudden big shifts in fluids/electrolytes make haemodynamically unstablepatients difficult to manage
⚫Haemodiafiltration⚪ A combination of the two
⚫Continuous vs intermittent
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Dialysis Filtration
⚫Diffusion
⚫Moves down a concentrationgradient across a semi-permeable membrane
⚫<5,000 daltons (500-2,000)
⚫Convection
⚫Pressure gradient drives water and molecules through a highly permeable membrane
⚫ <30-40,000 daltons (10,000-30,000)
Dialysis compared to CVVH
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Considerations
Composition of replacement fluid • All the potassium that is removed should soon become level in replacement fluid
• If remains high- check input or likely cell death releasing potassium
• No phosphate in replacement fluid-look to replace- regular phosphate Sandoz before gets too low and requires IV
• Set amount of fluid removed and replacement fluid added before blood
returned to patient.
Anticoagulation often required-Check local policy and recommended
plan with DVT prophylaxis
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Doses during filtration
• Ask “what harm I am going to do if give too much
• “What harm if give too little”• Check reason for filtration
– Sepsis, don’t reduce antibiotic doses
• Avoid renal toxic drugs• Some doses may be higher
– Fluconazole• Renal Handbook only good for
pharmacokinetics
Drug Clearance Likely
• Small water soluble molecules
• Lower levels of protein binding
• Smaller Volume of Distribution
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TPN
• TPN is not an emergency drug so should not be started out of hours.
• Check for local guidelines and advice
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Delirium
Very common in crit care. Patients are screened daily• Types: Hyperactive -Restless, agitated, hyper vigilant, paranoid,
hallucinations, aggressive, combative
• Hypoactive: Lethargic, short attention span, withdrawn, apathetic
• Mixed: combination
• Non-pharmacological
Multi-component interventions may be helpful
• Pharmacological
• Atypical antipsychotic (Quetiapine, Olanzapine, Risperidone)
• Typical antipsychotics (Haloperidol)
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Directly deliriogenic drugsAnalgesics
CodeineFentanyl
MorphinePethidine
Cardiovascular agentsAtenololDigoxin
DopamineLidocaine
CorticosteroidsDexamethasoneHydrocortisone
Prednisolone
AntidepressantsAmitriptyline
Paroxetine
AntipsychoticsChlorpromazine
Hypnotic agentsChlordiazepoxide
Diazepam
AnticonvulsantsPhenytoin
Phenobarbitone
AntimuscarinicsAtropineHyoscine
Miscellaneous agentsFurosemideRanitidine
AntihistamineChlorphenamine
Promethazine
AntiemeticsProchlorperazine
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Everyday considerations
• Stress ulcer prophylaxis if not being fed
• Infection prevention
• Bowel management
• Electrolytes
• Eye/mouth hygiene
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Step down patients
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Meds rec on step down
Considering stopping crit care meds- omeprazole, amiodarone, antipsychotics, inhalers
Consider restarting usual meds but only if needed
Summary points
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Don’t be afraid of critical care, you know lots of info already
Drugs which are unusual to you are familiar to critical care staff, and often titrated against response
Route is important. Can be IV via either peripheral line or central line (check out how many lumens) but also NG, PO, rectal, etc.
Just as important to stop drugs as start them
In COVID patients, avoid unneccessary fluid, low dose steroidsconsidered
Never be afraid to ask
Daily checklist
Organ system Issue
General Meds rec, U&Es, coag, interactions, allergies, co- morbidities (including alcohol and smoking)
CVS BP meds, pump failure, fluid balance
GI Feeding (ideally enteral), bowels, blood glucose, prokinetic, stress ulcer
Renal urine output, urea/creatinine, dose adjustments, CVVH
CNS Sedative or analgesic effects, previous meds, tolerance and withdrawal
Infection Micro (including route and choice), steroids
Liver LFTs (abnormal in sepsis), drug interactions
Haem Clotting, DVT prophylaxis
Administration Available stock, instructions on safe admin, compatibilities
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Useful resources
• SPC
• Other pharmacists – UKCPA Message board
• Renal drug handbook – only for pharmacokinetics
• UKCPA guidance e.g. minimum volumes, dosing in
extremes of bodyweight, compatibility
• ToxBase
• Medusa
• UpToDate
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Acknowledgements
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Emma Boxall, Specialist Critical Care PharmacistGreg Barton, Specialist Pharmacist Critical Care and Burns