Anaesthesia Flashcards
What are the contra-indications to a Biers Block?
Indications- Co-operative patient with an isolated below elbow fracture or laceration requiring repair or manipulation
Contraindications
- Local anaesthetic allergy
- Open fracture
- Severe hypertension (>180 SBP)
- Sickle cell disease
- Severe crush injury or compromised circulation
- Patient not consenting or agitated
- Morbid obesity
- Risk of lymphoedema
- Raynauds phenomenon
- Scleroderma
- Known significant arm PVD
What are the potential complications of a Bier’s block?
LAST
Methaemglobinaemia (only prilocaine)
Discomfort
Allergy/anaphylaxis
Failure of block
Neurovascular compromise
How should a Bier’s block be performed?
What medication is used in a Bier’s block?
Lidocaine 0.5% (can dilute from 1% with normal saline) 3mg/kg max 200mg)
Prilocaine 0.5% with 3mg/kg max 240mg (can dilute as above)
What is the maximum cuff pressure of a Biers block and how high should it be above the SBP?
100mmHg above SBP
Maximum 300mmHg
What safety checks should be done for a Biers block before proceeding with local anaesthetic injection?
- Contralateral IV access
- At least 3 lead cardiac monitoring
- Make sure pnuematic tourniquet is double cuffed
- Pulse check to ensure efficacy
- Perform in resus capable area
- Check LA dosing guidelines
How should LAST be treated?
- Basic supportive measures
- Crystalloids for hypotension
- Benzos for seizures
- 1-2mls/Kg (aka mmol’s/kg) of 8.4% sodi bic for broad complex arrhythmias
- 1.5ml/kg 20% intralipid followed by 15ml/kg infusion over an hour
- If Methaemoglobinaemia suspected then give 1-2mg/kg IV methylene blue over 5mins
What are the contraindications to Ketamine for sedation (without paralysis)?
Allergy/ADR
LRTI/URTI intercurrent
Upper airway stimulating procedure
Porphyria
Thyroid disorders (relative)
Psychosis (relative)
Cardiac disorders sensitive to elevated heart rate (ie MS)
What are the doses of ketamine for sedation?
- 4mg/kg IM with top dose of 2mg/kg
- 1mg/kg IV with top up 0.5mg/kg
- IM takes 3-5mins, last 15-30mins, wares off fully within 120mins
- IV takes 1-2mins, last 10-20mins, wares off fully within 30mins
Suggested to give premedication with antiemetics (ie ondansetron) due to risk of N/V with Ketamine
What is the management of laryngospasm?
Give ketamine slowly, reduces rate of laryngospasm and initial stunned apnoea
What is the DOPES mnemonic for deterioration on a ventilator?
Displacement of ETT
Obstruction of ETT
Patient: pneumothorax, PE, aPO etc
Equipment: Ventilator issue, tubing kinked, 02 disconnected etc
Stacked breathes: Bronchospasm, incorrect ventilator settings
How is post intubation hypoxia managed
Disconnect tube and attached BVM
Give 100% Fi02 with PEEp valve
Determine patient vs Equpiment
Check EtCo2, consider laryngoscopy to confirm position
If BVM easy but no chest movmeent then likely dislodged ETT
If BVM hard with slight chest movement consider R) mainstem, bronchospasm, hyperinflation and pneumothorax, block/kinked ETT
If BVM easy, chest moves and patient improves then consider circuit/machine issue
What is the dosage of Ketofol for sedation?
0.5mg/kg ketamine then 0.5mg/kg of propofol
Less risk of N/V, hypotension and bradycardia
Higher risk of apnoea
Paradoxically higher risk of laryngospasm
What is the dose of midazolam for procedural sedation?
0.1mg/kg, in paeds max 2mg
Can do repeat doses every 5 mins
Usually not enough to lose consciousness alone, but will provide anxiolysis and amnesia
What are the complications of FI blocks?
Failure of procedure
LAST
Neural injury
Vascular injury/bleeding
Infection
Anaphylaxis
What are the different methods for confirming ETT placement? What are the limitations?
ET CO2
- Unable to exclude right mainstem
Auscultation
- Unable to exclude high riding ETT, also can have referred breaths from the stomach
Direct visualisation
- Unable to exclude right mainstem
Chest Xray
- Takes time, slight risk of misdiagnosing oesophageal intubation
Bronchoscopy
- Equipment/operator dependent
USS
- User dependent
What are the criteria for extubation in the ED?
- Need for intubation resolved
- Minimal 02 need
- Minimal pressure support
- Adequate spont resp effort
- Awake and co-operative
- Unimpaired neurmuscular state (strong hand grip, sustained head rise)
- Not a very difficult intubation
What techniques can be used to make LA injection hurt less?
- Small needle
- Slow injection
- Warm solution
- Smallest volume neccesary
- Topical anaesthetic prior
- Nerve block vs local infiltration
What regional blocks can be performed to help with rib fractures?
Serratus anterior plane block
Paravertebral block
Erector spinae plane block
Intercostal block
Thoracic epidural (usually for flail chest or >4 rib fractures)
What is capnography used for in the ED? Which part of the capnograph waveform represents deadspace ventilation?
- Confirmation of ETT placement
- Ongoing monitoring of ventilation
- Helps to assess ROSC in ACLS and can be used to predict unssuccesful resus if <10mmHg at >20mins
- Helps assess compression quality, aiming for >20mmHg
- Helps monitor for resp depression in procedural sedation
- Monitoring ventilation in patients with altered mental status
- Monitoring response to therapy in patients with resp distress ie COPD and Asthma
- A-B = anatomic deadspace ventilation
- C-D = alveolar deadspace ventilation
- EtCO2 sampled at point D
What are the causes of abnormally low and high ETCO2?
High
- Malignant HTN, sepsis, thryoid storm, severe hyperthermia
- Hypoventilation
- release of tourniquet, bicarbonate infusion
- Underventilation, ventilator failure, partial obstruction, CO2 absorber dysfunction
Low
- Hypothermia, metabolic acidosis
- Hyperventilation peripheral or central, APO, apnoea,
- Shock, cardiac shunt, PE
- Oesophageal intubation, tubing disconnection, over ventilation
How should a falling/flatline etCO2 trace be assessed and managed?
Management
- Check pulse/BP to assess for cardiac arrest, ACLS if in cardiac arrest
- Check for disconnection in circuit
- Disconnect and manually ventilate with BVM at 1.0 Fi02
- Check for cuff leak
- Pass suction catheter if suspecting an obstruction eg mucous plug
- Assess tube dislodgement, remove and replace if dislodged
What are the causes of a flat EtCO2 trace?
Causes
- Cardiorespiratory arrest
- ETT disconnection or complete obstruction
- Circuit disconnection
- Capnography disconnection
- Ventilator dysfunction
- Oesophageal intubation*
- Apnoea test in brain death
- Very severe bronchospasm
What are the causes of a rising EtCO2?
Increased CO2 production
- NaHC03, fever, malignant hyperthermia, tourniquet release, overfeeding syndrome, laparoscopy insufflation with CO2
Pulmonary perfusion increase
- Increased CO or MAP
Alveolar ventilation decrease
- Rebreathing* (at risk of breath stacking aka hyper inflation)
- Partial airway/circuit obstruction, bronchial intubation
Equipment Malfunction
- Exhausted CO2 absorber, inadequate fresh gas flow, ventilator tubing leak, ventilator malfunction
What is the cause of a falling EtCO2 trace?
Decreased innate CO2 production
- Hypothermia
- Metabolic acidosis
Pulmonary perfusion decrease
- Reduced CO, hypotension, PE
- cardiac arrest (degenerate to a flat trace)
Alveolar ventilation change
- Hyperventilation, bronchospasm, partial airway obstruction
- Apnoea (will degenerate to flat trace)
Apparatus malfunction
- partial extubation, partial ETT obstruction
- Leak in sampling, ventilator malfunction
What treatments can help with a post dural pucture headache?
- Caffeine PO BD 300mg
- IV fluids
- Gabapentin/Pregabalin
- GON/sphenopalatine nerve block
- Epidural blood patch
Why is performing an RSI in obese patients more challenging than normal?
- Increased thoracic fat distorts airway position when on back, use ramping to overcome this
- Large breasts
- Reduced intraoral space
- Harder to palpate CTM
- Raised Intra-abdominal pressure increased the risk of aspiration
- Facial fat makes BVM harder
- Reduced FRC and atelectasis
- Higher metabolic demand leads to faster desaturation
- Difficult IV access
- less reliable NIBP readings
What is an FI block and what are the contraindications?
Fascia Illiaca
- Blocks the femoral, obturator and lateral cutaenous nerve of the thigh
- Usually use Ropivicaine 0.75%
Contraindications
- Local anaesthetic allergy
- Overlying infection
- patient refusal
- Amiodarone therapy (Ropivicaine)
- Severe hepatic disease
- 2nd-3rd degree heart block with no PPM in situ
Dosing
- 2-3mg/kg
- Or 0.4ml/kg max of 0.75%, thus aiming for 0.25ml/kg as safe dose
- Or 0.8ml.kg of 0.375% Ropivicaine, thus aiming 0.5ml/kg safe dose
What is the Cormack-Lehane score for intubation grading?
Grade 1
- Full view of the glottis
- <1% chance of difficulty
Grade 2a
- partial view of glottis
- 4-13% of difficulty
Grade 2b
- only posterior edge or arytenoid cartilage seen
- 65% difficulty
Grade 3
- only epiglottis seen
- 85%
Grade 4
- epiglottis not seen
- almost 100%
What is the predicted BVM difficulty mnemonic?
MOANS
Mask Seal
- Bushy beard, crusted blood, disruption to facial continuity in trauma
Obesity/Obstruction
- Obesity, pregnancy, angioedema, ludwigs angina, upper airway, abscess, epiglottis
Age
- >55
No Teeth
- Leave dentures in edentulous patients
Sleep Apnoea/Stiff lungs
- COPD, asthma, ARDS
What is the predicted intubation difficulty mnemonic?
LEMON
Look externally
- Lower facial disruption, bleeding, small mouth, agitated patient
Evaluate (3-3-2 rule)
- Mouth opening >3 fingers
- 3 finger breadths from tip of mandible to anterior neck
- 2 fingers from the base of the mandible to the thyroid neck
Mallampati Score
- I Complete visualisation of soft palate
- II Complete visualisation of the Uvula
- III base of the uvula only
- IV No soft palate seen
Obstruction/Obesity
- obesity
- stridor, muffled voice, not swallowing secretions, sniffing position/tripod
Neck Mobility
- Trauma C-spine precautions
- Arthritis, ank spondylitis
What is the mnemonic for difficult LMA insertion?
RODS
Restricted mouth opening
Obstruction
Disrupted/Distorted anatomy
Stiff lungs/cervical spine
What is the mnemonic for difficult front of neck access?
SHORT
Surgery
- ie previous laryngectomy etc
Haematoma
- also infection, abscess, any swelling
Obesity/Obstruction
Radiation
- To the neck, distorts tissue planes
Tumour
- Neck and mediastinal tumours
What strategies can be used to reduce the risk of viral transmission during ETT insertion?
- Negative pressure room
- Minimal number of clinicians (ie 3)
- Full PPE and N95
- Most experienced intubator
- VL, bougie/stylet
- Avoid ventilating without a closed circuit
- Clamp the ETT whenever disconnected
- Minimise coughing with sedation/paralysis
- Use of a viral filter
- Inline not external suction devices
