Cardiogenic Shock |
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Ashit V. Hegde and Khusrav Bajan |
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A 55-year-old male patient was admitted to the hospital with history of chest pain for about 3 h. He was drowsy, extremities were cold, and his blood pressure was 84/60 mmHg. His electrocardiogram showed extensive anterior ST elevation myocardial infarction.
The management of acute coronary syndrome and its complications has increasingly been protocolized. Timely implementation of these protocols especially in patients with shock is the essence as “time is muscle.” Cardiogenic shock carries a high 30-day mortality within the range of 30–40%.
Step 1: Urgently resuscitate
•The patient with prolonged cardiogenic shock needs to be ventilated in spite of normal oxygenation parameters to decrease oxygen consumption by the respiratory muscles and utilization of low cardiac output by vital organs.
•Use sedatives that are less likely to worsen hypotension during intubation, namely, etomidate, ketamine, and fentanyl.
•In patients who are not clinically in heart failure, cautious fluid resuscitation with proper hemodynamic monitoring should be initiated.
A.V. Hegde, M.D., M.R.C.P. (*)
Critical Care, P.D. Hinduja National Hospital & Medical Research Centre, Mumbai, India e-mail: ahegde1957@gmail.com
K. Bajan, M.D.
Emergency Department, P.D. Hinduja Hospital and Medical Research Centre,
Mumbai, India
R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach, |
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DOI 10.1007/978-81-322-0535-7_20, © Springer India 2012 |
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A.V. Hegde and K. Bajan |
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Step 2: Take a focused history and quick physical examination to differentiate causes of chest pain with shock
•Acute myocardial infarction (AMI)
•Pulmonary embolism
•Pneumothorax
•Pericardial tamponade
•Acute dissection of the aorta
•Esophageal perforation
•Pneumonia
Step 3: Investigate urgently to confirm cardiogenic shock
•Cardiac enzymes (Trop T, Trop I, CPK MB)
•ECG—serially
•2D echocardiogram
Step 4: Ascertain the cause of cardiogenic shock (Table 20.1)
• Complicated AMI is the most common cause of cardiogenic shock.
Table 20.1 Causes of cardiogenic shock
Acute myocardial infarction Large infarction
Right ventricular infarction Papillary muscle rupture
Free left vetricular wall rupture Pericardial tamponade Ventricular septal defect
Dilated cardiomyopathy
Myocarditis
Myocardial contusion
Acute mitral/aortic regurgitation
Left ventricular outflow tract obstruction
Pericardial tamponade
Step 5: Initiate medical management
•Aspirin: 160–325 mg of soluble or chewable aspirin should be administered, but the decision to administer clopidogrel should be made only after angiography (in case the patient needs urgent coronary artery bypass graft [CABG]).
•Thrombolysis: In the presence of hypotension, thrombolytic drugs may not reach the coronary vessel. Thrombolytic therapy is therefore not very effective in established cardiogenic shock. Consider thrombolysis only if primary percutaneous intervention (PCI) is not possible urgently. Thrombolytic drugs are more effective if administered after the BP has been raised (preferably after the use of an intra-aortic balloon pump [IABP]).
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Step 6: Initiate hemodynamic management (see Chap. 18)
•A central venous line preferably under ultrasound guidance to avoid arterial punctures and an intra-arterial line (preferably radial) should be urgently inserted.
•The use of a pulmonary artery catheter is optional.
•Urine output should be monitored hourly.
•Urgent 2D echo is mandatory to rule out mechanical causes of shock (papillary muscle rupture, acute ventricular septal defect, free wall rupture, and pericardial tamponade). 2D echo also gives an idea of left ventricular ejection fraction (LVEF) and left ventricular (LV) filling pressures.
•Fluid boluses may be cautiously administered to most patients with cardiogenic shock. Even patients with pulmonary edema may have intravascular volume depletion because there is redistribution of fluid from the intravascular compartment into the alveolus. These fluid boluses should be guided carefully by frequent physical examination and intravascular pressure monitoring.
•Most patients will also need a vasopressor and an inotrope. The least dose of these medications required to maintain adequate perfusion to the tissues should be used. Dobutamine (2.5–10 mcg/Kg/min) is the inotrope of choice in patients with a BP of more than 80 mmHg. Levosimendan, a calcium sensitizer inotrope, has also been increasingly used in cardiogenic shock as it has a relatively less effect on increase in oxygen consumption by the myocardium. Dopamine (5–20 mcg/Kg/min) is used if the BP is less than 80 mmHg or if the patient’s BP drops further with dobutamine. There is increasing evidence that many patients with cardiogenic shock are inappropriately vasodilated because of an inflammatory response. Noradrenaline (or vasopressin) may be tried in patients not responding to dopamine/dobutamine.
Step 7: Consider inserting an IABP (see Chap. 101)
•Early insertion of IABP helps to support the coronary and cerebral circulation.
•It acts as a bridge to cardiac revascularization procedures, insertion of other mechanical assist devices, or cardiac transplant.
•In cases of myocardial stunning, it buys time while other therapeutic measures take effect.
Step 8: Consider coronary revascularization
•Urgent left heart catheterization and revascularization, if coronary anatomy is suitable, should be undertaken.
•Timely primary PCI is the preferred mode of reperfusion in patients with cardiogenic shock complicating AMI.
•Proper hydration and N-acetylcysteine (600 mg b.i.d for 3 days) should be given to prevent contrast-induced nephropathy as these patients are at risk of acute kidney injury (AKI).
•Urgent CABG is indicated in patients with coronary anatomy not favorable for PCI.
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•The shock study demonstrated a 13% decrease in mortality in patients with cardiogenic shock assigned to early revascularization (primary PCI or CABG).
•Although revascularization should be performed as early as possible, there is a survival benefit for up to 48 h after MI and within 18 h of the onset of shock.
Step 9: Manage specific situations
Mechanical complications |
Mechanical complications of MI, including rupture of the |
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ventricular septum, free wall, or papillary muscles, need |
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urgent surgical correction (after temporary stabilization with |
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an IABP). |
Right ventricular (RV) |
Patients with RV dysfunction and shock need adequate |
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right-sided filling pressures to maintain cardiac output. |
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However, overzealous fluid therapy may do more harm by |
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overdistending the RV and compromising LV filling. RV |
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end-diastolic pressure of 10–15 mmHg is optimum. If the |
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patient remains hypotensive in spite of reasonable fluid |
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therapy, inotropes and IABP are indicated. |
Pericardial tamponade |
It is an uncommon but rapidly reversible cause of cardiogenic |
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shock. Its existence should be actively sought in all cases of |
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shock by a bedside echo looking for evidence of diastolic |
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compression of the right side of the heart. Immediate |
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pericardiocentesis is lifesaving. Fluid boluses and vasopres- |
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sors may be used as a temporizing method. |
Step 10: Consider rescue therapy in refractory shock
•The left ventricular assist device (LVAD) placed surgically or percutaneously should be considered in patients’ refractory to medical therapy and IABP.
•It should be instituted early before irreversible organ damage occurs to work as a “bridge” before definitive therapy like cardiac transplantation is available.
•Extracorporeal assist devices have been increasingly used in the ICU as a bridge to definitive therapy (Fig. 20.1).