FRCA Notes

Perioperative Care of the Patient Undergoing Cardiac Surgery

The curriculum asks us to describe 'the principles of the perioperative anaesthetic management of patients for cardiac surgery'.

In a similar vein, one must be able to 'correctly assesses the risk of operation in a patient who has cardiac or respiratory disease, using common scoring systems'.

This page is therefore a catch-all for any patient presenting for any cardiac surgery.

More detailed perioperative management for specific cardiovascular disease states can be found on the cardiac conditions page.

Resources

  • Cardiac surgery is a heterogenous group of surgical techniques which instigate a variety of physiological insults
  • The greatest effect on outcome from cardiac surgery will come from the patient's pre-existing comorbidities
  • However, surgical factors such as urgency, complexity, surgical duration and use of/duration of cardiopulmonary bypass will also influence patient recovery

  • ERAS programmes are collections of interventions which, although alone may provide little benefit, when applied as a bundled pathway result in improvement in patient experience and outcome
  • Patients undergoing cardiac surgery will benefit from ERAS programmes owing to common themes of comorbidities and amongst surgeries

Patient information

  • Patients should undergo an informed consenting process
  • This includes:
    • Education on the surgery itself
    • Discussion of anticipated events
    • Importance of pre-operative interventions
    • Post-operative expectations about early mobilisation and returning to normal function

Primary care

  • Modifiable patient risk factors should be addressed early by the referring team
  • This includes optimisation such as:
    • Diabetic control
    • Management of hypertension
    • Management of anaemia
    • Smoking cessation
    • Reducing alcohol intake

  • Consider carotid Doppler if past history of CVA
    • May need to increase MAP ± use cerebral oximetry if high risk patient, presence of carotid disease or aortic arch surgery

Risk assessment

  • Risk scoring systems include:
    • European System for Cardiac Operative Risk Evaluation (EuroSCORE II), which predicts 30 day mortality
    • Society of Thoracic Surgeons adult cardiac surgery risk score (STS)
    • The Parsonnet additive risk stratification model for cardiac surgery
  • These scoring systems focus on overall procedural risk; they do not necessarily incorporate a holistic consideration of all of the patient's risk factors
  • Equally, they were derived from patients undergoing coronary bypass grafting and the results mayn't be applicable to some surgeries, particularly minimally invasive or transcatheter techniques

  • Biochemical risk factors which influence outcome should be screened for and optimised, including:
Deranged glycaemic control
(HbA1c  >48mmol/mol)		 Hypoalbuminaemia
(<30g/L) 		Anaemia
(Hb ≤100g/L)
↑ morbidity Prolonged mechanical ventilation 5x ↑ mortality
↑ risk post-op. MI AKI ↑ morbidity
↑ risk post-op. wound infection Infectious complications
Longer hospital stay
↑ mortality

Prehabilitation

  • Prehabilitation is the process of augmenting a patient's functional status, in order to better withstand the stress of surgery
  • It has multiple facets: patient education | correcting nutritional deficiencies | optimised physical fitness | psycho-social support

  • Cardiac surgery school
    • Provides an environment for the patient (and their relatives) to learn about the perioperative process
    • Educates patient as to how they can influence their perioperative course
    • Reduces psychological stress and improves recovery

  • Exercise programmes
    • Deemed safe in those with cardiorespiratory conditions
    • Uses HIIT ± muscular strength training; increases lean body mass to body fat ratio
    • May decrease perioperative sympathetic dysregulation and insulin resistance
    • Improves physical + psychological readiness for surgery
    • Is associated with better patient experience, shorter length of stay and reduced incidence of complications

  • Lifestyle modifications
    • Smoking cessation from 3-8 weeks before surgery significantly reduces serious cardiorespiratory complications and wound infections
    • Excess alcohol use and obesity are also associated with poorer outcomes
    • Prehabilitation focuses on individual counselling of benefits

  • Nutritional supplementation started 7-10 days pre-operatively may improve outcome in those with hypoalbuminaemia

Carbohydrate loading

  • Cochrane review demonstrated giving carbohydrate drinks the night before and 2hrs before cardiac surgery is safe
  • It is associated with improved cardiac function immediately after cardiopulmonary bypass
    • In non-cardiac patients it improves post-operative glycaemic control and is associated with earlier return to normal GI function

  • In general, patients should be fasted for the minimum amount of time possible

Other facets

  • Avoid sedative pre-medications where possible
  • Administer PPI ± gabapentin pre-medication

Reducing surgical site infections

  • Overall incidence is 1.1-7.9%

  • Negative sequelae include prolonged hospital stay, high morbidity/mortality and increased healthcare-related costs
  • Optimising modifiable risk factors such as smoking status and glycaemic control play a vital role in reducing infections

  • There are a variety of methods available to reduce surgical site infections, including:
    • Intranasal therapies to eradicate Staph. aureus; up to 1/3rd of patients are carriers & they have a 3x risk of surgical site infections or bacteraemia
    • Weight-based cephalosporin antibiotics 30 - 60mins before skin incision, repeated 4hrly
    • Hair removal using clippers
    • Skin sterilisation with cleaning solution
    • Maintaining normothermia
    • 48hrly dressing changes

Avoiding hyperthermia

  • Bypass is normally carried out at normothermic or hypothermic body temperatures
  • The patient may be subjected to inadvertent hyperthermia (core temp. >37.9°C), especially during re-warming from hypothermic bypass
  • Hyperthermia, however, is associated with increased post-operative neurological injury, renal dysfunction and infection

  • Temperature measurement
    • During CPB: the blood temperature at the oxygenator’s arterial outlet is a surrogate market of cerebral temperature
    • During re-warming: assume the oxygenator arterial outlet temperature is an underestimate of cerebral perfusate temperature
    • During weaning & post-bypass:use PA catheter or nasopharyngeal probe temperature

  • Avoid cerebral hyperthermia by limiting the arterial outlet blood temperature to <37°C

  • Keep the temperature gradient between venous inflow and arterial outlet to ≤10°C in order to:
    • Avoid gas emboli generation during cooling
    • Avoid out-gassing during re-warming

  • Safe re-warming
    • If arterial outlet temperature is <30°C, maintain a maximal gradient between venous inflow and arterial outlet of 10°C
    • If arterial outlet temperature is ≥30°C:
      • Maintain a maximal gradient between venous inflow and arterial outlet of ≤4°C
      • Maintain a rewarming rate of ≤0.5°C/min

Blood products and tranexamic acid

  • Bleeding after cardiac surgery is a common complication
    • It carries a significant impact if it requires re-sternotomy (incidence 0.7-7.6%)
    • Mortality after re-sternotomy is 15%

  • TXA intra-operatively reduces need for blood transfusion, reduces the incidence of major haemorrhage and tamponade requiring re-operation
  • Total maximum dose 100mg/kg (higher doses associated with seizures)

  • Other blood conservation strategies reduce need for peri-operative transfusion:
    • Identifying and correcting pre-operative anaemia
    • Intra-operative cell salvage and use of viscoelastic haemostatic assays
    • Avoidance of post-operative hypothermia

  • The effect of cardiopulmonary bypass on platelet function may necessitate higher platelet counts post-surgery e.g. >750

  • The complexity of open cardiac surgery invariably requires CICU admission post-operatively, even with straightforward procedures
  • Those who undergo minimally invasive procedures still often required higher level care

Extubation

  • Prolonged post-operative ventilation is associated with prolonged ICU/hospital stay, increased morbidity and mortality
  • Early extubation (<6hrs) is endorsed in Cardiac ERAS guidelines; certainly prolonged (>24hrs) mechanical ventilation should be avoided

Analgesia

  • Multi-modal, opioid-sparing analgesia is the key to reducing the undesirable physiological effects of pain and avoiding the known adverse effects of opioids
  • Pharmacological methods include paracetamol, magnesium, ketamine, gabapentinoids and dexmedetomidine
  • LA infiltration of sternal wound and drain sites
  • Regional techniques include thoracic epidural, paravertebral, erector spinae or paravertebral blocks
  • Avoid NSAIDs owing to increased incidence of renal dysfunction and thromboembolic events following cardiac surgery

PONV

  • There are high rates of PONV following cardiac surgery, up to 67%
  • It contributes significantly to negative patient experience, as well as its physiological effects of adrenergic stimulation, impaired mobility and slower return to normal diet

Glycaemic control

  • Hyperglycaemia >10mmol/L is associated with glucose toxicity, oxidative stress, increased inflammation and a prothrombotic state
  • Interventions to improve glycaemic control improve outcomes, so VRII should be used to maintain glucose <10mmol/L

Temperature management

  • Post-operative hypothermia (<36°C) in the 2-5hrs after admission to CICU is associated with bleeding, infection, prolonged length of stay and higher mortality
  • Adequate rewarming prior to separation from cardiopulmonary bypass should have taken place
  • Use of non-invasive methods such as forced air blankets, fluid warmers and adequate ambient temperature should be used to avoid hypothermia

Fluid balance and renal function

  • Goal-directed protocols for cardiac surgery reduce hospital length of stay and complications (but not mortality)
  • Initiation intra-operatively does not confer any additional benefit to a protocol applied solely on CICU

  • AKI affects 22-36% of patients undergoing cardiac surgery

  • Measuring urinary biomarkers & activating a renal-protection/haemodynamic optimisation bundle based on their detection reduces the incidence of AKI post-cardiac surgery
    • Biomarkers include 'tissue inhibitor of metalloproteinases-2' (TIMP-2) and 'insulin-like growth factor binding protein 7' (IGFBP7)
    • These markers can identify patients at risk for developing AKI before increases in serum creatinine or reduced UO

Delirium

  • 50% incidence after cardiac surgery, and is associated with decreased survival, hospital re-admission and diminished long-term functional recovery
  • Use systematic screening tools e.g. CAM-ICU at least once per shift
  • Management should address risk factors and use techniques including sedation holds, orientation, correction of sleep-wake cycle and use of visual/hearing aids

VTE prophylaxis & early mobilisation

  • Early mobilisation reduces pulmonary and thromboembolic complications
  • Early removal of catheters and drains can help facilitate early mobilisation
  • Patients should undergo post-extubation PT assessment and aim to sit up on the bed and start deep breathing exercises within 4hrs of extubation

  • Mechanical VTE prophylaxis is mandatory; instigate chemical prophylaxis once drains removed