Investigations

The following investigations will be helpful in the early assessment and management of a patient post ROSC:

Chest x-ray

A chest x-ray will:

• Check line and tube positioning
• Rule out iatrogenic complications e.g. pneumothorax
• Aid diagnosis

A chest x-ray is shown with right internal jugular vein central line (vertical arrow), and endotracheal tube (horizontal arrow) both sited correctly.

ECG

This set of ECG images shows a range of complications of the post-arrest syndrome. Click on the ECGs to enlarge.

Fig 1: ECGs should be required routinely if ischaemia, infarction or arrhythmia is suspected (this shows 1:1 atrial flutter, not ventricular tachycardia. ECG changes commonly occur with subarachnoid haemorrhage and can mimic ischaemia or infarction – interpret cautiously.	Fig 2: This ECG shows a regular broad complex tachycardia, probably ventricular tachycardia
Fig 3: This renal dialysis patient walked into the department complaining they felt unwell. Potassium was 8.9 (note peaked T waves)	Fig 4: This ECG displays the same renal dialysis patient displayed in Fig 2b who deteriorated as the team struggled to secure IV access
Fig 5: This ECG was taken from a 55-year-old male who had had ROSC after VF arrest. Initially he had collapsed with chest pain, sweating and vomiting. Anterior myocardial infarction (not ventricular tachycardia)

Ultrasonography including Echo

This can be useful in diagnosing the cause of cardiac arrest, some examples:

• Massive pulmonary embolus (PE)
• Pericardial effusion (causing tamponade)

An assessment of overall cardiac contractility and filling status can also be made.

Pleural spaces can be assessed. Free fluid and abdominal aortic aneurysm can be sought in the abdomen. [9]

Further investigations

Potassium should be checked on venous or arterial blood gases, and should be maintained at 4-4.5 mmol/L to try and limit arrhythmias. [5]

An improving lactate post-arrest demonstrates reducing tissue ischaemia. [4] It is a valuable way to assess physiological response to therapy and is an independent predictor of mortality. [7]

The following table summarises the potential benefits of these investigations.