College Answer
. A 72 year old male with known triple vessel coronary disease has returned to the ICU following an uncomplicated coronary artery bypass grafting (CABG). An intraoperative transoesophageal echo showed good left ventricular systolic function and no significant valvular dysfunction. Mediastinal drains have been inserted and there is minimal blood loss. Thirty minutes after return to the ICU his BP falls to 70/40 mmHg.
Give the 4 most likely causes for this.
• Artifactual due to inaccurate monitoring system
• Hypovolaemia
• Vasodilatation associated with re-warming
• Vasodilatation associated with drugs (anti-hypertensives, vasodilators, sedation
• Anaphylaxis
• Pneumothorax
• Cardiac tamponade
Outline your immediate management
• Check monitoring system
• Fluid bolus
• Stop vasodilators
• Consider use of a short acting vasopressor such as metaraminol
• If not responding to fluid and short acting vasopressors consider a catecholamine infusion such as noradrenaline
• Cease any potential allergens
The patients BP stabilises and 2 hours later you are called to review him since he has developed significant shivering. List 4 possible treatment options
• Increase sedation / analgesia
• Consider paralysis
• Increase external warming
• Consider pethidine
On day 1, the patient is extubated and stable. You are shown the following ECG:
What does it show?
• Diffuse concave ST elevation suggestive of pericarditis
What treatment is required?
• If the patient is asymptomatic, then no treatment is required
1 hour later, quite unexpectedly, the patient has a VF cardiac arrest. What are your principles of management?
• Basic ALS. Immediate defibrillation, ensure airway and ventilate with 100% oxygen
• Contact the cardiothoracic team immediately and prepare for possible sternotomy
• Internal cardiac massage and internal defibrillation if re-sternotomy on the ICU
Discussion
The first part of the question calls for differentials for shock.
Relevant reading for this includes the following chapters:
The management of "shivering" in the ICU is somewhat more complicated. In this setting, one can assume that the patient is shivering because the process of their awakening has been faster than the process of their rewarming. The increased oxygen demand of the body can give rise to increased demand on the wounded myocardium, and this is to be avoided. Sedation, paralysis and more vigorous rewarming is the sensible solution. Pethidine is known to control rigors, and in one article it was used as a rescue agent to control post-bypass shivering before the authors resorted to pancuronium. Apparently, dexamethasone is another valid alternative.
In our study group, we were grateful to the contribution of one member, who sensibly pointed out that it would be worthwhile to take the patient's temperature before jumping to conclusions regarding the cause of their shivering. This broadens the range of management techniques (one might find themselves giving paracetamol instead of curare toxins, which is a markedly different approach).
