Defibrillation, ventilation, pacing and resuscitation are essential components of cardiac surgical care. The 2015 European Resuscitation Council (ERC) guidelines report the incidence of resuscitation as 0.7–8% after adult cardiac surgery. This wide range is almost certainly due to resuscitation interventions frequently being undertaken in house on many cardiac surgical ICUs, and therefore going under the radar of the clinical audit. Prompt and effective basic life support (BLS) and early defibrillation for shockable rhythms are the two most important interventions after cardiac arrest. Chest reopening and extracorporeal membrane oxygenation (ECMO) for patients with refractory cardiogenic shock are additional therapeutic options. As patients undergoing cardiac surgery become older and sicker, quality of resuscitation will continue to increase in importance.
Resuscitation Guidelines
Conventional basic and advanced life support guidelines provide a useful framework but require modification in the cardiac surgical ICU setting. The European Association of Cardiothoracic Surgery (EACTS) guidelines summarise the key modifications that must be considered for adult patients in cardiac arrest after cardiac surgery. Although current resuscitation algorithms typically divide arrests into two (shockable and non-shockable) limbs, EACTS subdivide the non-shockable category and utilise a three-limb approach. The EACTS three-limb model emphasises important initial differences in management of patients presenting with severe bradycardia or asystole compared to those presenting with pulseless electrical activity (see Figure 25A.1). Important changes in the revised 2015 European Resuscitation Council guidelines are discussed below.
Adult Basic Life Support
Maintaining the circulation has been promoted ahead of airway management and breathing in recent adult basic life support (BLS) guidelines. The traditional Airway, Breathing, Circulation and Defibrillation (ABCD) algorithm described in previous guidelines has been replaced by Circulation, Airway and Breathing (i.e. CAB). In general, 30 chest compressions at a rate of 100–120 per minute should now be given before any attempt to deliver rescue breaths. The efficacy of chest compressions can usually be verified in the ICU by studying the arterial pressure waveform. Interruptions to chest compressions should be minimised and last less than 10 seconds.
In situations where BLS is undertaken, the recommended ratio of chest compressions to ventilations is now 30:2. More chest compressions and fewer interruptions are achieved with this ratio than with the previously recommended 15:2 ratio. In the presence of a patent airway, effective chest compressions are considered more important than ventilation in the first few minutes of resuscitation. It should be borne in mind that coronary perfusion pressure progressively rises during chest compressions and rapidly falls with each pause for ventilation. Following a witnessed collapse in a patient with oxygenated arterial blood, the initial emphasis should normally be on chest compressions.
Because chest compressions may be injurious immediately following cardiac surgery, external cardiac massage is frequently deferred in the cardiac ICU providing defibrillation or external pacing therapy can be delivered within 30–60 seconds. The rationale for this approach and modifications to the Advanced Life Support (ALS) algorithm are discussed later.
Adult Advanced Life Support
The new 2015 Advanced Life Support (ALS) algorithm for the management of cardiac arrest in adults retains the shockable and non-shockable limbs (Figure 25A.2). There are subtle but important differences in recommendations for defibrillation for shockable rhythms in cardiothoracic ICU and the catheter laboratory. The EACTS guidelines include important advice on how to expedite the decision making and actual chest reopening process (see Figure 25A.1).
Figure 25A.1 EACTS guideline for resuscitation of a postoperative cardiac surgical ICU (or recovery) patient. From Dunning et al. (2009).
Pulseless VT/VF
Pulseless VT and VF account for the majority of underlying dysrhythmias in patients who survive cardiac arrest in hospitals. For every minute the chances of successful defibrillation decline by 7–10%. Specialist cardiothoracic units should be capable of early detection, rapid defibrillation and superior outcomes. In the setting of the cardiac ICU, when external cardiac massage may be injurious, immediate defibrillation (i.e. DCAB) should be the first line response for all monitored in-hospital VF arrests.
Since 2005, a single shock (>150 J biphasic or 360 J monophasic) has been recommended instead of three ‘stacked’ shocks, in general hospitals. Interruptions to CPR during delivery of three shocks and improved first shock efficacy of biphasic defibrillators were cited as reasons for the change. In practice, most cardiac surgical ICU and catheter laboratory staff were unconvinced by the evidence for single shocks and continued to deliver up to three stacked shocks in quick succession when treating VF. More recent EACTS and ERC guidelines recognised this and recommend three stacked shocks in quick succession for VF/VT arrests occurring in the cardiac catheter laboratory and cardiac surgical ICU. In addition, contrary to the latest guidelines, there is usually no need to commence chest compressions after a successful shock in invasively monitored cardiac surgical patients.
Non-VF/VT Arrests
A heterogeneous group of conditions may present as non-VF/VT cardiac arrest (Table 25A.1). Outcome is generally poor unless a reversible cause can be found and treated effectively. In the cardiac surgical ICU – where bleeding, hypovolaemia and tamponade are all readily treatable, and where additional therapeutic options are available – outcomes are considerably better than in the general ICU population. Examination of trends in RA pressure, PAWP and airway pressure all provide useful pointers as to the likely aetiology. Cessation of drainage from mediastinal drains does not exclude haemorrhage or tamponade as the drains may have become blocked. Although TTE and TEE echocardiography is often very useful in the cardiac ICU, echocardiography may miss localised collections and thus delay reoperation. Patients with clinical signs suggestive of tamponade should be reopened even if echocardiography is inconclusive.
Table 25A.1 An aide memoire to the causes of pulseless electrical activity and asystole
| The Four ‘Hs’ | The Five ‘Ts’ |
|---|---|
|
|
When faced with an arrest of this type, it is essential to:
confirm that VF is not being missed and that ECG leads or pads are correctly attached,
treat bradycardia with epicardial pacing if wires are present,
exclude tension pneumothorax,
exclude underlying VF in the presence of fixed rate pacing, and
consider chest reopening if closed chest CPR is unsuccessful.
Symptomatic bradycardia is extremely common in the cardiac surgical ICU. ALS guidelines no longer recommend atropine as first line treatment. In the cardiac surgical ICU, where tachycardia is equally undesirable, pacing (when possible) is the preferred option. If pacing is not an option (e.g. no wires in situ or failure to capture), isoproterenol or dopamine are often used. Management of asystole that fails to respond to pacing is an indication for prompt chest reopening.
Suggested modifications to the standard ALS algorithm are shown in Figure 25A.2.
Figure 25A.2 Algorithm for resuscitation after adult cardiac surgery. Six suggested modifications to the standard ALS algorithm are highlighted in the six bright yellow boxes to the sides and below. Therapeutic hypothermia may be considered after successful resuscitation. Adapted from the Resuscitation Council (UK) 2010 ALS algorithm.
Drugs in Advanced Cardiac Life Support
Although the use of vasopressors at cardiac arrests has become standard practice, proof of efficacy is limited. Epinephrine 1 mg is recommended every 3 minutes to improve coronary and cerebral perfusion. The American Heart Association has suggested that vasopressin may be used as an alternative to epinephrine. Clinical studies, however, have failed to demonstrate that either vasopressin or high dose epinephrine (5 mg) offers any additional benefit.
On the cardiac surgical ICU it is entirely appropriate to modify the recommended pharmacological management of a monitored cardiac arrest. An α-agonist or smaller initial dosages of epinephrine (0.1–0.2 mg) may be administered to minimise the risk of hypertension and tachycardia following successful resuscitation. For patients with VF/VT arrests, it is standard practice to attempt at least three shocks before giving any epinephrine.
The evidence supporting the use of antiarrhythmic drugs in VF/VT is surprisingly weak. Two studies of out-of-hospital VF/VT arrest demonstrated that the administration of amiodarone after three unsuccessful shocks increased the likelihood of survival to hospital admission. Significantly, neither study demonstrated that amiodarone improved survival to discharge. Despite this latter finding, amiodarone has now been promoted ahead of lidocaine in the pulseless VF/VT algorithm. A bolus of amiodarone 300 mg is recommended for VF/VT arrests that persist after three shocks but this should not delay surgical reopening (see below). A further dose (150 mg) may be given for recurrent or refractory VF/VT, followed by an infusion of 900 mg over 24 hours. Lidocaine can still be given for VF/VT if the patient has received amiodarone but the evidence supporting its efficacy is weak. Magnesium should also be considered if there is clinical suspicion of hypomagnesaemia. Administration of sodium bicarbonate should be considered if arterial or mixed venous pH < 7.1.
Airway and Ventilation
Table 25A.2 Waveform capnography during ALS
| Confirmation of tracheal intubation |
| Monitoring ventilation rate |
| Monitoring quality chest compressions |
| Identifying ROSC during CPR |
| Prognostication during CPR: failure to achieve CO2 value >1.33 kPa (10 mmHg) after 20 minutes CPR associated with poor outcome |
The Fourth National Audit Project (NAP4) of the Royal College of Anaesthetists reported that 61% (22 of 36) of airway events in the ICU led to death or persistent neurological injury. Major risk factors for adverse events included anaesthetic experience of doctors, out-of-hours airway interventions, patient obesity and failure to use (or correctly interpret) capnography. A recurrent finding was the failure to consider the possibility of oesophageal intubation when presented with a flat capnograph trace. As well as providing valuable information about endotracheal tube position and patency, and ventilation, capnography also provides invaluable additional information about return of spontaneous circulation and cardiac output (see Table 25A.2). The introduction of mandatory waveform capnography in the CICU has arguably made the single biggest contribution to improved patient safety on the CICU since the publication of the first edition of CTiCICU 1e nearly a decade ago.
Chest Reopening
Following surgery through a sternotomy, chest reopening is both a diagnostic and therapeutic option in the cardiac surgical ICU. In addition, chest reopening allows internal cardiac massage, which is considerably more effective than external chest compressions. Haemorrhage, tamponade, graft occlusion and graft avulsion are conditions likely to be remedied by this approach. Patients most likely to benefit are: those with a surgically remediable lesion, those who arrest within 24 hours of surgery and those in whom the chest is reopened within 10 minutes of arrest. Delayed reopening or the finding of a problem that is not amenable to surgery (e.g. global cardiac dysfunction) is associated with a poor prognosis. Recent resuscitation guidelines confirm that chest reopening should be triggered by:
three failed shocks in VF/VT arrests (i.e. one resuscitation cycle);
exclusion of reversible causes (e.g. tension pneumothorax) and failure of initial treatment for non-VF/VT arrest.
Chest reopening should not be used as a ‘last ditch’ manoeuvre after a prolonged period of unsuccessful resuscitation. Although some units advocate initially stopping all infusions and syringe drivers to exclude iatrogenic drug administration errors, the majority tend to continue infusions unless there is a clinical suspicion of inadvertent vasodilator flushing being responsible for loss of CO. Whichever policy is used, it is important to ensure that anaesthesia and analgesia are restored prior to chest reopening. The EACTS guidelines and Cardiac Advanced Life Support (CALS) courses recommend six key roles in the management of a cardiac surgical ICU arrest (Figure 25A.3).
