Anaesthesia Coffee Break The 5 critical effects of pregnancy on respiratory physiology
Jan 7, 2021
Explore the fascinating changes pregnancy brings to respiratory physiology. Discover why estrogen can complicate intubation and how reduced functional residual capacity impacts pre-oxygenation techniques. Learn about the increased minute ventilation influenced by progesterone and how this shifts CO2 response. The dynamics of lung mechanics take on new dimensions, with altered compliance and pressures. Finally, delve into how these physiological shifts affect the uptake of volatile agents in anesthesia. Tune in for insights critical to practice!
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Always Optimize Airway Positioning
- Position pregnant patients in the optimal intubating/ramped position before induction to reduce difficult airway risk.
- Anticipate airway swelling and trauma from estrogen-related mucosal friability and prepare gentle technique and backup devices.
Real Cases Of Unexpected Difficult Intubation
- Lahiru and Host recount cases where pregnant patients lying flat became very difficult to intubate unexpectedly.
- These experiences reinforce always optimizing position and preparation even when neuraxial anaesthesia appears to be working.
Reduced FRC Shortens Safe Apnea Time
- Functional residual capacity falls ~20% upright and ~30% supine at term, shortening safe apnea time despite pre-oxygenation.
- Supine reduction may approach closing capacity causing airway closure and shunt, worsening rapid desaturation.