Fast-Tracking

Determining if a patient is suitable to be fast-tracked or for enhanced recovery versus the need for more advanced care begins early in the patient pathway, during the preoperative assessment by the surgeon and anaesthetist. ‘Routine’ cardiac cases are ‘fast-tracked’ in a cardiac recovery unit, which is a part of the ICU. Such clinical areas are often managed by experienced nursing staff who follow institution-specific protocols while being overseen by a responsible physician. These protocols address issues such as the weaning from mechanical ventilation and the management of expected postoperative issues. These strategies have been safely implemented to facilitate early ICU and hospital discharge. It is important to emphasize the need for early involvement of specialized medical staff when there is deviation of a patient’s progress from a clearly defined pathway or anticipation of such an incident.

Transfer, ICU Admission and Handover

During the transfer from the operating room, uninterrupted invasive monitoring is essential for the early recognition of haemodynamic instability secondary to fluid shifts during movement and dysrhythmias. On arrival in the ICU it is important that there is a prompt handover to the nurse responsible for ongoing care. This should include anaesthetic and intraoperative details as shown in Box 7.1. This is usually performed while the ICU ventilator is being connected and monitoring (usually including capnography, invasive monitoring, oximetry and ECG) is switched from the portable monitor to the fixed ICU monitor. In patients who require epicardial pacing, it is important that the pacing is checked and changed from a fixed rate to demand mode as appropriate. Once the handover has been completed, an initial ABG should be drawn to ensure appropriate oxygenation and ventilation is being achieved. Baseline potassium, Hb and metabolic state should be reviewed and corrected as appropriate. If the patient is bleeding excessively, a baseline full blood count and coagulation screen and/or a thromboelastogram (TEG) should be acquired.

Mechanical Ventilation, Sedation and Analgesia

In the UK, it is widely considered that the risk of bleeding, haemodynamic instability and hypothermia following cardiac surgery outweighs any potential benefits of tracheal extubation in the operating theatre prior to transfer to ICU. Initially, a ‘full’ mechanical ventilation mode is selected, for example synchronized intermittent mandatory ventilation (SIMV) with an adequate rate (10–12 breaths per minute), tidal volume (6–8 ml kg⁻¹) and a modest PEEP (5 cmH₂O) to reduce postoperative atelectasis. As spontaneous respiratory effort returns, lower-rate SIMV with pressure-support ventilation (PSV) can be used. Eventually, ventilation using only PSV (to overcome the resistance of the ventilatory system) with a modest PEEP can be used prior to tracheal extubation.

In the setting of mediastinal bleeding, a higher PEEP (5–10 cmH₂O) may be used; however, this may have deleterious haemodynamic effects. Sedation and mechanical ventilation are usually continued for 30–240 minutes post transfer to the ICU to allow for rewarming and to exclude significant bleeding. Use of forced-air warming blankets can minimize the duration of postoperative hypothermia (<36 °C), which is not uncommon and can have adverse effects (Box 7.2). Many centres routinely use propofol for sedation due to its short and predictable duration of action. The criteria that should be considered prior to switching of sedation with a view to weaning ventilation and extubation are listed in Box 7.3.

Box 7.3 Criteria for withdrawing sedation and weaning from mechanical ventilation

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  Haemodynamically stable

  
  
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  Able to make a valid respiratory effort

  
  
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  Able to protect their airway

  
  
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  Fully rewarmed

  
  
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  Normalization of ABG

  
  
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  Acid–base balance within specified range

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Related

Related posts:

Chapter 3 – Diagnostic Techniques Chapter 6 – Weaning from Cardiopulmonary Bypass Chapter 14 – Surgery for Cardiomyopathy and Pericardial Disease Chapter 22 – Postoperative Paediatric Care Chapter 21 – Common Congenital Heart Lesions and Procedures Chapter 35 – TOE for Miscellaneous Conditions