Anaesthesia for Thoracic Surgery Flashcards
What are the consequences of opening the thoracic cavity?
Atelectasis will occur
Will decrease total lung capacity, vital capacity, functional residual capacity
Hypoxaemia common even with IPPV
Why is a thoracotomy painful?
Skin incision
Nerve damage
Retraction of ribs to allow surgical access
Inflammation at surgical site
Leads to hyperalgesia
Post-op pain = unwillingness to move chest wall = reduced efficacy of ventilation
What respiratory reasons might lead to opening the thorax?
Lung lobe torsion, bulla, neoplasia, abscess
What cardiovascular reasons might lead to us opening the thorax?
Patent ductus arteriosus
Persistent right aortic arch
Pericardectomy
Heart surgery
What occurs when a patent ductus arteriosus is clamped off?
Systemic BP increases
Profound bradycardia
What other reasons might we have for opening the thorax?
Oesophageal FB
Thoracic duct ligation
What pre-anaesthetic considerations should we have?
Be aware of risks - bleeding, hypotension, hypoventilation
Consider stabilisation e.g. chest drainage
Pre-oxygenation
Analgesia (infusions), minimise CVS depression
Describe fentanyl.
Potent anaesthetic-sparing substance - reduce inhalational gas % to minimise resp. depression
Why might we perform one-lung ventilation, and with what?
Pathology affecting one lung e.g. infection/tumour OR improve surgical exposure e.g. thoracoscopy
Double lumen tube OR endobronchial blocker
Describe one-lung ventilation with a single lumen ET tube.
Easy but possibly not effective
Risk of contamination between lungs
Difficult in big dogs due to tube length
Describe one-lung ventilation with an endobronchial blocker.
Requires bronchoscope and skill to place
Effective but expensive to buy
Avoid moving patients once placed to reduce risk of dislodgment/bronchial wall damage
Describe one-lung ventilation with a double lumen tube.
Tubes bulky and can be difficult to place
Can be done blind
Not achievable in big dogs due to tube length
Left and right bronchial tubes available
How can we troubleshoot hypoxaemia?
Check 100% FiO2
Check patency of ET tube (not dislodged/blocked)
Ensure CVS function optimised (appropriate depth of anaesthesia/circulating blood volume)
How can we manage hypoxaemia?
Switch to manual ventilation - few larger breaths to decrease atelectasis
Introduce PEEP
Reduce concentration of volatile agent / consider e.g. fentanyl CRI
Re-expand collapsed lung
How can we wean patients from the ventilator?
Consider alveolar recruitment manoeuvre
Time end of IPPV with closure and drainage of chest
Turn off ventilator and support respiration until breathes spontaneously
Decrease IPPV gradually to allow PaCO2 to rise
Decrease anaesthetic/analgesic drugs
Reverse NMBA before stopping IPPV