Patient W__yoF with Past Medical History significant for Chronic lymphocytic leukemia after Richter Transformation to Diffuse large B cell lymphoma, HFrEF secondary to chemotherapy toxicity (EF 15-20%), and paroxysmal Afib who presented as a transfer from Chippenham hospital for concerns of tumor lysis syndrome requiring CRRT in the setting of worsening leukocytosis (WBC > 400). She originally presented to outside hospital with worsening shortness of breath and orthopnea and was started on dobutamine/lasix gtt for ambulatory cardiogenic shock. Given worsening hyperkalemia patient needed transfer to VCU for CRRT. Patient found to be volume overloaded with decreased SvO2 and started on dobutamine/lasix gtt for ambulatory cardiogenic shock.
Thinking about this patient from a hemodynamic standpoint, how is this patient's Cardiac output, Cardiac index and Resistance?
We are thinking about this patient's clinical outlook. Her heart has pour squeeze (measured by the ejection fraction) into a very viscous (measured by the SVR) system.
Calculating the Cardiac output is done with Fick's principle
CO (L/min) = rate of O2 consumption(L/min) / (arterial O2 content - venous O2 content)
Let's assume: Rate of O2 consumption = 125ml/min; Patient's Hgb is 7.1.
To get cardiac Index we need to Calculate Arterial and Oxygen Content.
SaO2 = 100% and SvO2 22%, the patient is extracting a lot of oxygen.
O2 content = (O2 bound to hemoglobin) + (O2 solubilized in plasma) = (1.34 × Hb × SaO2) + (0.003 × PaO2).
O2 arterial content = 1.34 * Hb * SaO2 = 1.34 * 7.1 * 100% = 9.3
O2 Venous Content = 1.34 * Hb * SvO2 = 1.34 * 7.1 * 22% = 2.06
Plugging in the values we can solve for Cardiac Index
125 / (7.1 * 1.34 * 7) = 1.87 as Cardiac Index
Once we have cardiac index we can solve for cardiac output given that the BSA for the patient is 2.2.
CI = CO / BSA
CO = CI * BSA
CO = 2.2 * 1.8 = 4.0L
We have just shown that this patient has a low cardiac index of 2.2 and a low cardiac output of 4.0L. This paints her picture of cardiogenic shock secondary to HFrEF with low EF.
Now we can calculate the viscosity of her blood how much SVR she has.
To do that we use an equation similar to ohm's law. P/Q = R.
We can convert this equation to SVR = (MAP - CVP) * 80 / CO
MAP is calculated
104 / 3 + 70 * 2/3 = 81.33333. Let's say this is 89 as in the picture above.
and CVP is measured off of the line at 12.
SVR = (MAP - CVP) * 80 / CO
SVR = (89 - 12) * 80 / 4 = 1540.
This patient has a lot of resistance, but not as high as we would have suspected. Tumor lysis syndrome can create increased viscosity because all the viscous DNA particles are being lysed. Normal SVR is between 700 - 1500 dynes/sec/cm^-5. The patient had slightly increased viscosity.
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