Week - Anaesthesia for respiratory compromised patient Flashcards
What is safer…heavy sedation or general anaesthesia?
General anaesthesia is safer as it ensures that the airway is secured.
- ET tube and oxygen
- Monitoring (nurse designated with a GA patient)
- In control mor
Why is reducing stress and anxiety important in the reparatory compromised patient?
How can stress be reduced?
Stress = increased respiratory rate = increased demand for oxygen
Stress can be decreased by:
- Quiet and calm environment
- Good handling
- Sedation (e.g butorphanol)
- Antii-anxiety (e.g gabapentin)
Which weight should be used in an overweight patient?
Lean body weight
When overweight, the liver remains the same size and can only cope with the lean weight dose of drugs.
Be careful not to overdose!
Which animals should you have a larger selection of ET tubes for?
Brachycephalic = severity depends on size of tube
Animals with bronchoconstruction = harder to guess size
When an animal ‘sighs’ -> what could this be sign on and what should you do?
Sigh could suggest the lung is starting to collapse (Atelectasis).
Collapsed lung = reducing surfactant
Give breath to prevent the lung from collapsing -> ventilatory support
Why should you be careful with IVFT in respiratory compromised patients?
Too much IVFT = can overwhelm the pulmonary circulation, causing fluid to leak into the lungs, leading to pulmonary oedema, worsened respiratory function, and potentially life-threatening complications.
Mechanisms involved:
- increased hydrostatic pressure
- decreased oncotic pressure
- weakened cardiovascular system
- impaired lymphatic drainage
What ASA state are brachycephalic and respiratory distress patients?
ASA II-III = brachycephalic
ASA III-V = respiratory distress
What are premedication options for a dog in respiratory distress?
Opiod alone
Opiod (methadone, butorphanol) and one of :
- Dexmedetomidine
- Acepromazine
- Benzodiazepines
What should you always do and give patients in respiratory distress while preparing for sedation/intuabtion/further diagnostics?
Administer oxygen (mask, flow by, oxygen cage etc)
Gain IV access
What four other types of drugs (other than premedication and induction) can be given to a dog in respiratory distress?
Gastroprotectant (e.g, brachy’s prone to regurgitation)
- Omeprazole
- Metoclopramide
- Maropitant
Decongestants
- Xylometazoline
Beta agonist - open airway
- Terbutaline
Pain relief
- NSAIDs
- Paracetamol
What are premedication options for a cat in respiratory distress?
Opiod alone
Opiod (methadone, butorphanol) and one of:
- Dexmedetomidine
- Acepromazine
- Benzodiazepines
Opiod (methadone, butorphanol) AND Alfaxalone, AND midazolam
- Given IM
- Preferred for very sick cats
Ketamine AND midazolam
- IM and IV
- Less common as ketamine increases HR
What two other types of drugs (other than premedication and induction) can be given to a cat in respiratory distress?
Beta agonist - open airway
- Terbutaline
- Salbutamol
Pain relief
- NSAIDs
- Steroid
What are induction options for a cat or dog in respiratory distress?
- Alfaxalone IV (preferred, lower risk of apnea)
- Propofol IV (risk of apnea)
- Ketamine IV (less common)
Can combine alfaxalone or propofol with a benzodiazepine to reduce doses.
What should you remember to do when intubating?
- intubate as quickly as possible (to prevent SpO2 dropping)
- Cats = lidocaine
- Asses airway (BOAS, laryngeal paralysis, collapse, masses, polyps)
- Laryngoscope = visualise
- May need swab or suction
When sedating/GA an animal in respiratory distress, what should you tell the owner?
Convey information about the risk of anaesthesia
What inhalation agents are used to maintain anaesthesia?
Isoloflurane or sevoflurance
Adjust to maintain appropriate plane of anaesthesia
Other than inhalation agents, what can be used to maintain anaesthesia?
TIVA - total intravenous anesthesia
CRI - constant rate infusion
Use propofol or alfaxalone
Why should ET tubes be cut to a suitable length?
To minimise dead space
What should be monitored in patients undergoing anaesthesia when in respiratory distress?
Respiratory rate & effort, mucous membrane colour, CRT & reflexes
SPO2% and pulse rate
ECG (or oesophageal stethoscope if no other equip)
ET CO 2
Blood pressure (doppler)
Temperature
What is a normal ETCO2 value?
20-60 mmHg
What do these ETCO2 values tell you?
<20mmHg
>60mmHg
>5mmHg
<20mmHg - Hyperventilation
> 60mmHg - Hyperventilation
> 5mmHg - Rebreathing CO2
What causes hyperventilation on ETCO2?
Increased Respiratory Rate or Volume:
- Breathes faster or deeper than necessary, = expel more CO₂ than usual
Decreased CO₂ in the Blood:
- More CO₂ is exhaled = CO₂ in the blood (PaCO₂) decrease, leading to hypocapnia (low CO₂ levels in the blood).
Could suggest impending arrest
Could be caused:
- Leaks
- Extubation
- Disconnection
- Inadequate aesthetic plane
- Increase reps rate
What causes rebreathing on ETCO2?
Less CO2 expelled = higher concentration in the blood
Causes:
- Inadequate O2 flow rate
- Excessive equipment - dead space
- Exhausted CO2 absorbant
- One way valve not functioning
What causes hypoventilation on ETCO2?
Breathes slower or shallower than necessary, = expel less CO₂ than usual.
Caused by:
- Too deep anaesthesia
- Obesity
- Body position
- Airway obstruction
- Fluid or mass in chest
- Iatrogenic
What is the most critical period when doing a GA?
Recovery
- The most risk as support is withdrawn here
How can you minimise the risk in there recovery period?
Recover animals in prep area and carefully monitor
Supplement with oxygen as hypoxaemia is common
Be prepared to reintubate if the animal decompensates
Low dose sedation may be required
- reduce pain and stress to settle breathing
