Nar’ pump, mo’ problems, a case on cardiogenic shock
Resident Clinical Pearl (RCP) – June 2017
Mandy Peach, R2 FMEM, Dalhousie University, Saint John, New Brunswick
Reviewed/Edited by Dr. David Lewis and Dr. Kavish Chandra
It’s 11 pm, you’re doing the overnight shift and EMS calls in to report a patient with an ETA of 3 minutes: “80 yo female, found on floor in apartment by husband after reportedly feeling unwell for 2 days. Decreased LOC but arousable and responding appropriately. BP 82/36, HR 120, RR 22, Afebrile, oxygen sat 86% on 6L nasal cannula.”
You hear the vitals, and many differentials run through your mind – PE, sepsis, hemorrhage, tamponade. Your main concerns are: this person needs more airway support and they are in shock, and when you think shock you think ‘fluids’.
EMS rolls in with your patient and she looks awful – pale, mottled extremities and drowsy. She is being re-assessed, RT is present to switch to a face mask, IV access is being established and you’re about to pound her with fluids when you are handed her ECG:
1https://lifeinthefastlane.com/ecg-library/basics/inferior-stemi/
This lady clearly is having an inferior STEMI – there is marked ST elevation in II, III and aVF with early Q wave formation.
Take home point #1: In any Inferior STEMI, you must suspect RV involvement
Look for ST elevation in V1 and depression in V2, or ST elevation in lead III > lead II. If these are present – get a 15 lead ECG.1
On closer look at our patient’s ECG there is ST elevation in V1-V2 and the elevation in lead III is indeed larger than lead II. You order the 15 lead.
2 https://lifeinthefastlane.com/ecg-library/right-ventricular-infarction/
Look for ST elevation in right sided leads V3-V6, but the money is on V4R – ST elevation in this lead has a sensitivity of 88%, specificity of 78% and diagnostic accuracy of 83% for RV infarction2. Our patient does have RV infarction seen by ST elevation in V4R.
Take home point #2: RV involvement is associated with increased risk of cardiogenic shock and death with a mortality of 50% within the first 48 hours3. If there is RV involvement, giving nitroglycerin for chest pain is CONTRAINDICATED
Due to a poorly functioning RV, patients are pre-load sensitive2. If you decrease the pre-load then they have even less to pump, further worsening the hypotension.
So we have diagnosed this lady with cardiogenic shock secondary to AMI (the most common cause of cardiac related shock) and we determined she has RV involvement. We know we can’t give her nitroglycerin. Let’s reassess her status – the basic ABC’s.
Airway & Breathing – the RT has since advanced her to a non-rebreather with a sat level in the high 80’s. You suggest trying Optiflow or BiPAP as a temporizing measure – this lady is going to need to be intubated.
Take home point #3: Positive pressure ventilation requires a stable, cooperative patient – which is often not the case in cardiogenic shock
Positive pressure can decrease pre-load and potentially worsen hypotension3. It is a temporizing measure only. The majority will require endotracheal intubation to maintain their saturation as their work of breathing is a large expenditure of energy.
You successfully complete a RSI and the saturation improves to 94-98%.
Circulation – Repeat BP is 82/36. You complete a cardiac point-of-care-ultrasound (PoCUS) and see poor contractility, but no pericardial effusion or large clots suggesting chordae or papillary rupture. IVC is > 50% collapsible.
Take home point #4: On PoCUS, heart failure caused by acute ischemia will show a large RV and small LV secondary to low filling pressures, which is best seen on the apical 4 chamber view3
Your patient continues to be hypotensive – you give a small 500 cc bolus; you don’t want to overload a poorly pumping heart with fluid it can’t handle. However you anticipate that this will not be enough to improve her BP, and as she continues to be hypotensive her myocardial ischemia worsens, which subsequently worsens her pump dysfunction in a vicious cycle. She needs pressure support.
Take home point #5: Cardiogenic shock requires vasopressor support
If systolic BP > 90: Start with dobutamine for inotropy. Double up on agents – likely will need to add a vasoconstrictor. Dopamine is usually the next to add.
If systolic BP < 90: Can still use dobutamine, but need to add norepinephrine for vasoconstriction. Dopamine alone will worsen BP as it is a vasodilator.
3Tintinalli’s Comprehensive Guide to Emergency Medicine.
You start dobutamine and dopamine peripherally with the intention of obtaining central venous assess once stabilized.
In the meantime, cardiac labs and portable CXR are pending, you treat this patient as any other STEMI in terms of dual anti-platelet and anti-coagulation loading.
Take home point #6: Do not give beta blockers
Do not give beta blockers in RV infarcts as high risk of bradycardia and AV block due to ischemia of the AV nodal artery3.
You consult cardiology to activate the cath lab.
Take home point #7: Early revascularization in ischemic related cardiogenic shock is key
Early revascularization has a long term mortality benefit, preferably if done within 6 hours4. Catheterization or CABG is the preferred method over thrombolytic therapy.
You consult cardiology to activate the cath lab.
Back to our patient –
This lady did go on to the cath lab and had stenting of her RCA, however her infarct likely occurred > 48 hours before presentation. Unfortunately, despite aggressive vasopressor therapy and revascularization, she coded immediately after the procedure and resuscitation attempts were unsuccessful, emphasizing the poor prognosis associated with ischemia related cardiogenic shock.
Bottom line for cardiogenic shock: fluid bolus 500 cc 0.9% NaCl, vasopressor support and RSI. Early revascularization is key – catheterization is preferred. Despite these interventions, the diagnosis portends a poor prognosis.
References
- Inferior STEMI – Life in the Fast Lane https://lifeinthefastlane.com/ecg-library/basics/inferior-stemi/
- Right Ventricular Infarction – Life in the Fast Lane https://lifeinthefastlane.com/ecg-library/right-ventricular-infarction/
- Tintinalli, JE. (2016). Cardiogenic Shock (8th ed.) Tintinalli’s Emergency Medicine: A Comprehensive Study Guide (pages 349-352). New York: McGraw-Hill.
- Cardiogenic Shock – Literature Summary – Life in the Fast Lane https://lifeinthefastlane.com/ccc/cardiogenic-shock-literature-summaries/
This post was copyedited by Kavish Chandra @kavishpchandra
