Anaesthesia in Pulmonary disease Flashcards
What factors reduce FRC in the intra-operative period
- Supine
- Anaesthetic agents
- Muscle relaxants
- Immobility
- Surgical retractors
–> Faster desaturation (depleted O2 reservoir) and increased work of breathing (compliance curve)
What are the overall effects of anaesthesia on respiratory function
- Reduced FRC
- Atelectasis
- Inhibited hypoxic/hypercapnoec/acidotic RSP response
What peak flow rate range suggests inadequate coughing and accumulation of secretions with increased risk of LRTI
< 200 L/min
How can it be determined that the bronchodilator status for a patient is optimal
FEV1 reversibility with BD is less than 15%.
IF reversibility is > 15 % or 200 mL then consider delaying the case to optimise bronchodilator therapy
What pre-operative interventions are effective with regard to the optimisation of respiratory function in order to improve post-operative outcomes
- Rx cardiac failure and LRTI
- STOP smoking
- Physiotherapy x 4 weeks (fitness/coughing/breathing technique)
Describe intra-operative risk reduction for improved outcomes in patients with respiratory disease
- Avoid fluid overload
- Lung Protective Ventilation
- Vt: 6 - 8
- Pmean < 30 cmH20
- Ppeak < 35 cmH20
What post-operative interventions may improve postoperative outcomes
- Early mobilisation
2. Pain management
Define asthma
A chronic lung disease characterised by reversible episodic attacks of small airway obstruction due to bronchoconstriction, mucosal oedema and mucous plugging.
Describe the principles for intra-operative management of asthma
Avoid NSAID (cause bronchospasm)
Avoid drugs that release histamine (CIS/Morphine)
Avoid airway manipulation in light patient
Use drugs that cause BD: Volatiles/ketamine/MgSO4
Regional preferred
Describe IPPV for the asthmatic
Allow time for exhalation (I:E 1:4, Slow RR, higher Vt)
Permissive hypercapnoea ensure SaO2
Define apnoea
Cessation of airflow at the nose and mouth for at least 10 seconds.
- recurrent apnoea and hypoxaemia during sleep
What is STOP BANG
Snoring
Tiredness
Observed you stop breathing
Pressure (HPT)
BMI > 35
Age > 50
Neck circumference > 40
Gender: Male
What are the complications of OSA
Systemic HPT
Pulmonary HPT
CCF
RSP failure with CO2 retention
Which drugs pose a high risk for patients with OSA and why
Opioids (and sedatives)
- Distorted airway anatomy –> easy obstruction
- Increased sensitivity to opioids
Minimize opioids and observe in high care/ICU post op
How does smoking affect the risk of post-operative pulmonary complications
6 fold increase
What are the implications of smoking for anaesthesia
- 6 fold increase in POPC
- Associated with COAD, Ca lung, IHD, Vasc d/o
- Impaired mucociliary clearance
- Hyper-reactive airways
- Impaired immunity
- L shifted OHDC P50: reduced O2 delivery despite high SaO2 reading (COHb)
How does preoperative cessation of smoking alter the risk in a smoking patient
Cessation for 8 weeks
- risks same as non smoker unless irreversible lung damage/disease
Cessation for 12 hours
- COHb decrease –> improved DO2
- Decreased nicotine stimulatory effects
How long should patients who have had LRTI for elective surgery be postponed
6 weeks
Emergency surgery
- Optimize with physio/nebulizer/antibioitcs
- Attempt regional if feasible
Discuss the preoperative assessment of a paediatric patient with URTI
Postpone for 2 weeks unless:
Experienced anaesthetist can proceed with caution
unless fever/purulent sputum (suggestive of acute viraemia or 2ndry bacterial infection)
Describe the intra-operative complications of kids with URTI
Laryngospasm
Bronchospasm
Coughing
Desaturation
