The below summary is directed at all the similarly themed CICM written questions. "Why is this post-bypass patient so hypotensive", they whinge. Typically, an approach to the haemodynamically unstable cardiac surgical patient is being tested.
Such questions have included the following:
- Question 1 from the second paper of 2013
- Question 13 from the first paper of 2012
- Question 16 from the first paper of 2011
- Question 10 from the first paper of 2008
- Question 5 from the first paper of 2006
- Question 8 from the first paper of 2005
- Question 8 from the first paper of 2003
- Question 11 from the first paper of 2001
The candidate is expected to regurgitate a list of sensible differentials. The easiest way to organise these? Anybody's guess. Additionally, not only hypotension, but also hypertension can complicate post-op recovery, and it is included here because it also fits the definition of "haemodynamic instability".
The following table is presented as an alternative to the official college answer for Question 5 from the first paper of 2006.
| Type of shock | Cause | Diagnostic strategy | Management |
| Artifact of measurement | Arterial blood pressure measurement is inaccurate | Compare with non-invasive measurement and physical examination |
|
| Cardiogenic | Post-operative stunning of the myocardium | TTE, ECG, cardiac output measurement by PiCCO or PA catheter |
|
| Myocardial infarction | TTE, ECG, cardiac enzymes |
|
|
| Obstructive | Cardiac tamponade | TTE, CVP trace |
|
| Massive pulmonary embolism | TTE, CVP trace, ECG, CTPA |
|
|
| Tension pneumothorax |
Physical examination; CXR |
|
|
| Neurogenic | Infarction of spinal cord due to ischaemia or embolic events | Physical examination features, CT, MRI |
|
| Hypovolemic | Blood loss post operatively | Examination of drains, FBC, |
|
| Massive diuresis | Observation of fluid balance charts |
|
|
| Distributive | Vasoplegia | SVRI measurements by PiCCO |
|
| Anaphylaxis | Physical examination findings suggestive of angioedema |
|
Causes of post-cardiotomy instability, organised by alphabetical mnemonic order
A - Artifactual; art line is incorrectly zeroed
B - Tension pneumothorax
C - Cardiac tamponade
- Myocardial ischaemia
- Acute valvular failure (eg. of grafted valve)
- LVOT obstruction
- Post-bypass myocardial depression
- Arrhythmia (eg. AF)
D - Excess sedative (eg propofol)
E - Post-bypass hypocalcemia
F - Inadequate preload - need more fluid
G...
H - Haemorrhage - inadequately reversed heparinisation or DIC
- could be into pericardial sack or pleural space
I - Anaphylaxis; reaction to anaesthetic agents
- Vasoplegia due to circuit-induced SIRS
Causes of post-cardiotomy instability, organised by affected hemodynamic variable
- Preload
- Inadequate intraoperative fluid
- Haemorrhage
- Valve failure (mitral / tricuspid)
- Rate
- Bradycardia (or excessive tachycardia!)
- Rhythm
- AF or other arrhythmia
- Contractility
- Post-bypass myocardial depression
- Myocardial ischaemia
- Afterload
- Artifact: art line is incorrectly zeroed
- LVOT obstruction
- Anaphylaxis
- Vasoplegia
- Valve failure (aortic or pulmonic)
Post-cardiothoracic surgical bleeding complications
Sadly, bleeding complications are common enough to merit their own chapter. Excessive bleeding is usually due to one or more of the following factors:
- incomplete surgical hemostasis
- residual heparin effect after cardiopulmonary bypass
- platelet abnormalities (platelet dysfunction and thrombocytopenia – from bypass circuit consumption , antiplatelet agents etc)
- hypothermia
- postoperative hypertension
- clotting factor depletion
- hemodilution (dilutional thrombocytopenia and coagulopathy)
References
Frederick A. Hensley, Jr., M.D., Donald E. Martin, M.D., Glenn P. Gravlee, M.D. A Practical Approach to Cardiac Anaesthesia, 3rd ed. Sibylle A. Ruesch and Jerrold H. Levy. CHAPTER 9. The Postcardiopulmonary Bypass Period: A Systems Approach. 2003 by LIPPINCOTT WILLIAMS & WILKINS
André, Arthur C. St, and Anthony DelRossi. "Hemodynamic management of patients in the first 24 hours after cardiac surgery." Critical care medicine 33.9 (2005): 2082-2093.
Eagle, Kim A., et al. "ACC/AHA 2004 guideline update for coronary artery bypass graft surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery)." Circulation 110.14 (2004): e340.
Goepfert, Matthias SG, et al. "Goal-directed fluid management reduces vasopressor and catecholamine use in cardiac surgery patients." Intensive care medicine 33.1 (2007): 96-103.
Marik, Paul E. "Hemodynamic parameters to guide fluid therapy." Transfusion Alternatives in Transfusion Medicine 11.3 (2010): 102-112.
Almassi, G. Hossein, et al. "Atrial fibrillation after cardiac surgery: a major morbid event?." Annals of surgery 226.4 (1997): 501.
Maisel, William H., James D. Rawn, and William G. Stevenson. "Atrial fibrillation after cardiac surgery." Annals of Internal Medicine 135.12 (2001): 1061-1073.
BUCKLEY, MORTIMER J., et al. "Intra-aortic balloon pump assist for cardiogenic shock after cardiopulmonary bypass." Circulation 48.1S3 (1973): III-90.
Licker, Marc, et al. "Clinical Review: Management of weaning from cardiopulmonary bypass after cardiac surgery." Annals of cardiac anaesthesia15.3 (2012).
Lavana JD, Fraser JF, Smith SE, Drake L, Tesar P, Mullany DV. Influence of timing of intraaortic balloon placement in cardiac surgical patients. J Thorac Cardiovasc Surg 2011;140(1):80-5.
Maas, Jacinta J., et al. "Cardiac Output Response to Norepinephrine in Postoperative Cardiac Surgery Patients: Interpretation With Venous Return and Cardiac Function Curves*." Critical care medicine 41.1 (2013): 143-150.
Hajjar, L., et al. "Vasopressin Versus Norepinephrine for the Management of Shock After Cardiac Surgery (VaNCS study): a randomized controlled trial." Critical Care17.Suppl 2 (2013): P222.