You have been asked to assess a 76-year-old male, scheduled to have a verv large incisional hernia repaired electively. He has a history of obstructive sleep apnoea (OSA) requiring nocturnal continuous positive airway pressure (CPAP). A recent echocardiogram, done to evaluate pedal oedema and newly diagnosed elevated creatinine, has revealed an ejection fraction of 55%, a right ventricular systolic pressure RVSP of 90 mmH , and moderate tricuspid regurgitation (TR). He has a history of recurrent deep venous thrombosis (DVT) and pulmonary embolism (PE) due to deficiency of Factor V Leiden and is currently on Rivaroxaban.

a) List the specific risks associated with his co-morbidities in the perioperative period.
(40% marks)

b) Outline strategies that could be used to minimize these risks in the perioperative period.
(60% marks) 

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College answer

a) 
OSA:  
•    Acute respiratory failure,  
•    Cardiac arrhythmias,  
•    Cardiac ischaemia including cardiac arrest 
•    Risk of exacerbation by opiates may make analgesic management difficult 
 
Pulm hypertension:  
•    Acute right heart failure during perioperative period related to hypoxia and pain, Severe hypoxaemia,  
•    Cardiac dysrhythmias,  
•    Renal failure 
 
Renal dysfunction:  
•    Fluid overload,  
•    Electrolyte and acid base imbalance,  
•    Altered drug metabolism 
 
DVTs, PE, Factor V Leiden deficiency:  
•    High risk of thrombotic events esp PE with exacerbation of RHF.  
 
Anticoagulation:  
•    Bleeding risk,  
•    Thrombotic risk if ceased and not adequately covered. 
 
b) 
Preop: 
•    Consider need for surgery,  
•    Consider timing of surgery o Surgery should be done when co-morbidities are optimised 
o    Organisational factors: Surgery should be conducted when ICU support available, experienced surgical and anaesthetic team available, early on list (so not cancelled), in hospital with appropriate support (ICU and usual physicians) 
 

•    May be relevant to discuss goals of therapy with patient, surgical team and pre-existing physicians 
•    Optimise cardiac status especially with respect to pulmonary hypertension,? need for pulmonary vasodilators. Cardiology input would be valuable 
•    Optimise respiratory status especially with respect to nocturnal NIV; settings, interface 
•    Plan anticoagulation over perioperative period. 
•    OK to mention IVC filter if recent PE. But not necessary 
•    Optimise renal function; may need renal consult and exclusion of reversible causes 
•    Liase with surgeon, anaesthetist, treating physicians regarding management plan 
 
Intra-operative 
•    Use of regional techniques / local blocks to reduce requirement for systemic analgesia 
•    Appropriate monitoring and lines 
 
Post-operative If intubated: 
o    Early extubation and early mobilisation to avoid atelectasis if possible o Consider role of extubation to NIV o Continue usual nocturnal NIV 
•    Consider opiate sparing analgesic regimen, consider regional techniques (will need to consider anticoagulation issues) 
o    Avoid NSAIDS due to renal dysfunction 
•    Avoid fluid overload

o Maintain vascular tone with low dose noradrenaline 
o    Consider vasopressin if high dose pressor required due to less effect on pulmonary vasculature 
•    Restart anticoagulation as soon as safe, in keeping with pre-operative plan o Consider surveillance duplex monitoring if > 24-48hours off anticoagulation 
•    Avoid nephrotoxic medications 
 
Organise follow-up with usual physicians on discharge to the ward. 
 

Discussion

a)

Lets list the problems and consider the risks associated with them, in order of their appearance.

Problem Risks
Expected extensive abdominal procedure
  • Increased risk of post-op atelectasis, which will increase the pulmonary resistance even further
  • Significant analgesia requirements
  • Long procedure
OSA on CPAP
  • Prolonged recovery time
  • Propensity to somnolence and hypoxia with sedatives
Pulmonary hypertension
  • Haemodynamic compromise and right heart decompensation with positive pressure ventilation
Factors V Leiden deficiency
  • Increased propensity to develop DVTs and PEs in this context (the procedure by itself already confers a high risk of this)
Anticoagulation with DOAC
  • Potential for bleeding intra- and post-operatively
  • Makes neuraxial anaesthesia more risky

b)

To mitigate some of these risks, the following strategies may be considered:

Risk Strategy

Increased risk of post-op atelectasis

  • Intraoperatively, carefully titrate PEEP 
  • Extubate on to NIV

Significant analgesia requirements

  • Thoracic epidural
  • Multimodal analgesia

Long complex procedure

  • Early multidisciplinary engagement with the surgical team and anaesthetics, so a plan of management can be decided upon.

Prolonged  recovery from anaesthetic

  • Use short-acting anaesthetic agents, eg. desflurane
  • Rely on non-opiate analgesia, eg epidural or regional techniques
  • Admit the patient to the ICU intubated
  • Wake in the ICU and extubate when completely awake

OSA: Propensity to somnolence and hypoxia with sedatives

  • Intermittent CPAP following extubation
  • Rely on non-opiate analgesia
  • Instruct the patient to bring their CPAP machine with them
  • Consult their respiratory physician for advice on titrating the pressure in the post-operative period, and organise an early follow-up
  • Consider perioperative weight loss, if the procedure can be delayed (and if the patient is obese)
  • Consider corrective airway surgery prior to this abdominal surgery

Worsening of pulmonary hypertension

  • Consider perioperative pulmonary vasodilators
  • Post-operative nitric oxide or nebulised prostacycline
  • Avoid excessive preload for the RV (restrictive fluid resuscitation strategy)
  • Inotrope/vasodilator/avasopressor/fluid therapy should be guided by advanced haemodynamic monitoring, be it PA catheter or TOE
  • Ensure normoxia (hypoxia may worsen the RV afterload)
  • Avoid excessive use of noradrenaline (think about using vasopressin instead)

Thrombophilia and anticoagulation

  • Stop Rivaroxaban two days before the procedure
  • Bridge with another shorter acting or reversible anticoagulant: either admit the patient to start a heparin infusion, or use subcutaneous therapeutic dose enoxaparin at home.
  • Ensure the use of mechanical thromboprophylaxis
  • If there is an epidural, debate with the anaesthetist as to when and how the epidural should be removed in terms of timing it with a pause in anticoagulation

Interestingly, the college recommends to avoid fluid overload. That's probably accurate as the term "overload" implies "excessive load", which is by definition bad. You should avoid excessive bad fluid loading. But, the term "adequate fluid resuscitation" is good. Or at least adequate. Gille et al (2014) recommended the use of a "restrictive" strategy, guided by TOE or PA catheter.

References