76-year-old lady for elective TKR
- Significant knee pain, impacting QoL
- COPD, mild. 60 pack year smoking history
- Ceased smoking to facilitate TKR
- Peripheral vascular disease, multiple revascularization procedures. On apixaban
- BMI 46
- NIDDM. Poor glycaemic control
- Difficult to obtain accurate history in clinic
- Some indications of poor medication compliance
- On ?CPAP for OSA. Advised to bring to hospital.
- Extensive perioperative work-up, including delay to improve glycaemic control
- Presented for TKR. Uneventful intraoperative course.
- Developed Type 2 respiratory failure in PARU
- Home machine not functioning due to water ingress, sent to biomed
- Commenced on NFNP with little effect
- Reviewed by respiratory CNC in PARU. Patient well known to service
- Patient has significant OHS and is on home BiPAP (IPAP 17, EPAP 9)
- Device history revealed recent non-compliance with therapy
- Respiratory department sourced a replacement machine.
- Patient stable in recovery on usual BiPAP settings and discharged to ward.
Conduct of anaesthesia
- Spinal with intrathecal morphine 100mcg – consensus opinion that this was the optimal anaesthetic choice as avoided parenteral opioids.
- Some anaesthetists routinely use 150mcg morphine but would decrease to 100mcg in patients at risk of postoperative respiratory depression
- Consensus in literature than 100mcg is optimal dose for avoidance of respiratory depression
Could this situation have been avoided?
- Difficult history, multiple complex comorbidities
- Patient unaware of differences between CPAP and BiPAP
- Non-compliant with therapy
- Respiratory CNC provided extremely valuable input and avoided an unplanned HDU admission
Perioperative management of suspected OSA/OHS
- Clinic guideline under development, ongoing discussions with respiratory dept
- Sleep studies are time-consuming and turnaround time from referral to initiation of CPAP is around 6 months
- No RCT evidence to support reduction in perioperative morbidity and mortality with initiation of CPAP therapy.
- Observational data would suggest that OSA patients have worse perioperative outcomes and there are benefits to initiating CPAP perioperatively. (Anesth Analg 2015;120:1013–23)
- Aim is to identify those at highest risk of postoperative pulmonary and cardiac complications
- OHS – more complex sleep disorder with raised HCO3 and PaCO2. Majority also have OSA. These are patients to identify and treat perioperatively.
- Perioperative assessment: STOPBANG (>3) then perform ESS. If ESS (>8) – consider referral for sleep studies