Question 1

Created on Tue, 05/12/2015 - 02:40
Last updated on Tue, 08/11/2015 - 18:40
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A 76-year-old female is admitted to the ICU following elective aortic and mitral valve replacement. Transoesophageal echo assessment at the end of surgery showed an ejection fraction of 20%. Her preoperative creatinine was 340 μmol/L. Total bypass time was 240 minutes. On arrival in ICU the patient has the following indices;

  • Temperature 35°C
  • Atrial pacing (AAI) 80/min
  • Systemic blood pressure 85/55 mmHg
  • Pulmonary artery pressure 60/30 mm Hg
  • Cardiac index 1.5 litres.min.m-2
  • Systemic vascular resistance 1700 dyn.sec.cm--5
  • Pulmonary artery wedge pressure 10 mmHg
  • Central venous pressure 8 mmHg
  • The patient is currently on adrenaline 4μg/min by infusion.

a) List the specific clinical and haemodynamic issues for this patient on admission to ICU.

b) Outline your management of these issues.

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College Answer

a) The main clinical and haemodynamic issues identified are:
Elderly female patient post double valve surgery.
Pre-existing renal impairment.
Long bypass time.

Systemic hypotension (MAP 65 unlikely to be adequate for this patient).
Low output state (CI, EF post bypass).
Increased afterload / vascular impedance (SVR).
Probable fluid responsiveness (PAWP, CVP).
Moderate pulmonary hypertension.
Low core temperature.

b) This patient is high risk (female, age, long bypass time, pre-existing renal impairment, low EF). Management consists of:

  • Re-warming.
  • Judicious fluid replacement as she re-warms.
  • Improved volume state may augment CI but given poor EF unlikely to be sole intervention needed.
  • Titration of adrenaline infusion, aiming for CI > 2.2
  • Bedside echo to evaluate effect of fluid and increased adrenaline, exclude tamponade and check valve function (mitral regurgitation can increase PAP and decrease cardiac output).
  • Consideration of other vasoactive agents (dobutamine, milrinone, levosimendan) or IABP insertion if persisting low output state.
  • Assess adequacy of pacing and consider changing mode to A-V pacing (heart block common after AVR) and /or increasing rate to 90 bpm.
  • Correct post-op coagulopathy and replace blood losses to maintain Hb > 80 G/L. Surgical review if significant blood loss via drains.
  • Evaluation of any other cause of low output state e.g. tension pneumothorax, dynamic hyperinflation.
  • Close monitoring of renal function and early institution of renal replacement therapy if oligo-anuric or rising creatinine.
  • Consideration of inhaled nitric oxide to reduce pulmonary hypertension and RV afterload.

Discussion

This patient they have given you is slightly unwell. I have reformulated the answer into a systematic approach to this problem. The answer below is question-specific (as they generally should be) - a generic approach to the haemodynamically unstable cardiac surgical patient is discussed elsewhere.

  • Issues
    • Cardiogenic shock
    • Hypovolemia
    • Pulmonary hypertension
    • Hypothermia
  • Assessment
    • Examination, including dynamic manoeuvres to assess for fluid responsiveness
    • ECG to exclude STEMI
    • CXR to exclude pneumothorax
    • Arterial blood gas
    • Mixed venous blood gas
    • Formal TTE to examine valve function and sclude tamponade
  • Management
    • Re-warm patient
    • Sedate and paralyse patient to decrease whole-body oxygen demand
    • Maintain Hb ~ 80 and SpO2 ~ 100% to maintain satisfactory tissue oxygen delivery
    • Maintain heart rate and rhythm control with pacing and antiarrhymic drugs (eg. amiodarone); consider increasing rate to 90
    • Optimise RV preload: give fluid bolus 20-40ml/kg
    • Increase RV + LV contractility with milrinone or levosimendan
    • Decrease RV and LV afterload with milrinone or levosimendan (pulmonary and systemic vasodilation)
    • Decrease mycoardial workload with IABP especially if there is evidence of ischaemia with inotorope use
    • Maintain satisfactory diastolic pressure with noradrenaline

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.