Note, this video is comprised of portions of chapter 6A and a video that I made for EMCrit.org on IVC collapse
Learning Module Eight
2. Read this very brief essay: ICU Physiology in 1000 Words: Venous Doppler & Volume Tolerance
3. For more information, consider this EMCrit podcast on the topic.
Part C [complete together] ----------------
1. Return to your concept map for IVC collapse from module 2, can you fit the great vein Doppler pattern into this schema? Explain your thinking to each other.
2. If you imagine yourself as a red blood cell sailing through the portal vein and into the hepatic vein, how might the time course of the right atrial pressure affect your forward egress? Draw a cartoon with your partner of a fearless red blood cell making this voyage in a healthy patient and in the patient above.
3. How might a collapsing IVC affect the hepatic vein Doppler waveform? How might it affect the portal vein Doppler waveform? Explain this in terms of the sailing red blood cell.
4. Together, come up with at least 3 clinical scenarios where a pulsatile portal vein may be seen and volume removal could be dangerous. To confirm your suspicions in these cases, for what other clinical findings would you look?
5. Together, reflect on the case from module 1; what do you think this patient’s portal vein would look like and why? As a bonus, do the same for the case in module 2.
6. Reconsider the case from part A. and the true or false questions. Are you more or less likely now to give that patient a fluid challenge? What further information might you want to know? Hypothesize what would happen if you were to start the patient on Precedex? Hypothesize what would happen to his portal vein if you increased the CPAP level to 20 cm H2O – think in terms of RV preload and afterload using the Guyton Diagram.
7. With your learning partner, explain to each other how you will use great vein Doppler as a diagnostic tool moving forward.
8. Find another learning team and share your sailing red blood cell comic strip; give each other feedback.
Intended Learning Outcomes
Interpret the portal vein Doppler waveform as it relates to the central venous pressure
Relate the central venous pressure waveform to the great vein Doppler waveform
Integrate the great vein Doppler waveform into your understanding of Guytonian physiology
Hypothesize how common interventions in the ICU would change the great vein Doppler waveform and portal vein pulsatility.
Part A [complete alone] ----------------
A 72 year old man with known systolic dysfunction with an LVEF of 25% is admitted with progressively worsening dyspnea. He has missed a few dialysis sessions after feeling malaise and fevers. His wife – a pet therapy hospital volunteer – was recently diagnosed with influenza. He states that he has been consuming large amounts of canned soup during his illness; as well, he has been using ibuprofen for his generalized body aches. A sepsis alert is called for an elevated lactate and abnormal vital signs, and he is given 30 mL/kg of normal saline as mandated by the surviving sepsis campaign. Thereafter he becomes very short of breath and hypoxemic. CPAP is applied at 10 cm H2O and his breathing work is slightly improved. A repeat lactate level is unchanged and additional fluid loading is considered. Prior to giving more crystalloid, the senior ED resident evaluates both the patient’s IVC collapsibility and portal vein pulsatility. She notes that the patient has significant inspiratory collapse of the IVC and a bounding portal vein pulse.
T or F: the patient is hypervolemic?
T or F: the patient’s lactate will improve following further fluid loading?
T or F: the pulsatile portal vein means that the patient requires volume removal?
T or F: increasing the PEEP will lead to a more pulsatile portal vein?
T or F: the patient’s ultrasound findings are consistent with uremia-induced cardiac tamponade?
Reflect on modules 1 & 2 and what you have learned about IVC physiology and the central venous pressure. How have those modules coloured your interpretation of this case? Have you ever used portal vein pulsatility or the hepatic venous waveform to inform your clinical management? If so, what question were you asking? If not, do you have any perception of what venous Doppler means? Do you think a clinical, pre-test probability is important when integrating these ultrasound findings into your management? If so, how?
Part B [complete alone] ----------------
1. Watch this video
Heart-lung.org will provide a comprehensive, on-line tutorial in cardiovascular and respiratory physiology for the interested medical student, resident and fellow.
The first 4 chapters will cover basic physiology and pathophysiology with an emphasis on the Campbell and Guyton Diagrams.
The remaining 4 chapters will focus on clinically-relevant topics in the intensive care unit; the discussions will be largely drawn from the physiology covered in the first half of the textbook.