a pt of ac. MI with oliguris,hypotension with a Swan-Ganz ca

Discussion in 'USMLE STEP 2 CS' started by s.varun, Nov 22, 2005.

  1. s.varun

    s.varun Guest

    60-year-old woman is admitted to the hospital after an acute inferior myocardial infarction. She is noted to be oliguric, and has a blood pressure of 80/55 mm Hg. A Swan-Ganz catheter is placed, revealing a diminished pulmonary capillary wedge of 4 mm Hg, normal pulmonary artery pressure of 22/4 mm Hg, and an increased mean right atrial pressure of 11 mm Hg. Which of the following is the most appropriate next step in management?
    A. Balloon angioplasty
    B. Digoxin
    C. Fluids
    D. Intraaortic balloon counterpulsation
    E. Vasopressors



    HYPOVOLEMIA CAN BE ONE OF THE COMPLICATIONS OF ACUTE MI
    CAUSES INCLUDE---

    1) SEVERE VOMITTING ASSOCIATED WITH AMI AND CONSEQUENTLY REDUCED FLUID INTAKE OR
    2) PREVIOUS VIGOROUS OR CURRENT DIURETIC THERAPY MOSTLY WITH FUROSEMIDE

    FOR EARLY DIAGNOSIS WE HAVE TO DO SWANZ GANZ CATHETER STUDY AND MEASURE WHAT IS CALLED PULMONARY CAPILLARY WEDGE PRESSURE ( SWANZ-GANZ CATHETER IS INSERTED INTO INTERNAL JUGULAR VEIN ---SUPERIOR VENA CAVE---RIGHT ATRIUM---RIGHT VENTRICLE---PULMONARY ARTERY---PULMONARY CAPILLARY ----)

    HERE IT IS WEDGED IN THE PILMONARY CAPILLARIES AND IT MESAURES THE LEFT heart PRESSURE INDIRECTLY .
    SINCE LEFT heart IS THE ONE WHICH IS MOST COMMONLY AFFECTED IN ACUTE MI AND RESPONSIBLE FOR HYPOTENSION WE NEED TO KEEP THE LEFT heart PRESSURE OPTIMUN AS MUCH HIGH AS WE CAN TO MAINTAIN THE BLOOD PRESSURE OF THE PATIENT.

    THIS CAN BE DONE BY GIVING FLUIDS AND SIMULTANEOUSLY KEEPING CHECK ON THE LEFT heart PRESSURE i.e. PCWP.
    IF WE GIVE TOO MUCH OF FLUID THEN PCWP MAY INCREASE AND PATIENT MAY DEVELOP PILMONARY EDEMA AND BECOME HYPOXIC. SO PCWP HAS TO BE ACCURATELY MONITORED AND MAINTAINED OPTIMALLY WHEN YOU GIVE FLUIDS TO THESE PATIENTS.

    THE IDEAL RANGE OF PCWP IS APP. 20 mm Hg

    1) IF IN A PATIENT OF ACUTE MI WHO HAS HYPOTENSION AND PCWP IS LOWER THAN THIS VALUE THEN SUSPECT HYPOVOLEMIA AND TREAT HIM BY GIVING IV FLUIDS AND SIMULTANEOUSLY MEASURING PCWP.

    2) IF IN A PATIENT OF ACUTE MI AND HYPOTENSION IF THE PCWP IS MORE THAN THIS VALUE THEN THE PATIENT IS HAVING ACUTE PUMP FAILURE OR WHAT WE CALL ACUTE LVF. THIS KIND OF PATIENT IN FACT NEED TREATMENT WITH DIURETICS RATHER THAN FLUID REPLACEMENT BECAUSE HE IS AT A RISK FOR DEVELOPING PULMONARY EDEMA.. AND BEST FOR THESE PATIENTS WOULD BE WHAT WE CALL INTRA-AORTIC BALOON COUNTER PULSATION OR IABP. SINCE IT HELPS IMPROVE LEFT heart FUNCTION.


    i wud like u to look at the rt. atrial pressure too, which is HIGH here...........
    The Swan-Ganz tracing indicates that the patient has an elevated right-sided pressure and a low-filling pressure. Cardiac output is decreased as a result of insufficient left heart filling pressures. This is due to the RIGHT ventricular infarct, which causes backing up of venous blood and decreased forward flow, producing a decrease in left ventricular filling, as indicated by the low wedge pressure. The treatment for this patient is aggressive fluid administration.
    The patient had a right ventricular infarct, presumably from involvement of the right coronary artery. Balloon angioplasty (choice A) may ultimately be needed to correct the underlying cause of the infarction. However, the acute event has passed, and the patient must first be stabilized. She will ultimately need a cardiac catheterization.
    Digoxin (choice B) is not needed in this patient, since she is not in left sided heart failure. Positive inotropy is not needed as much as fluid resuscitation. Also, the patient is not in atrial fibrillation.
    If the patient had sustained a left ventricular infarct, she may have needed afterload reduction in the form of intraaortic balloon counterpulsation (choice D). Since the patient sustained a right ventricular infarct, however, afterload reduction is not as important as is preload repletion.
    The patient is hypotensive. If the hypotension does not resolve with fluid repletion, then vasopressors such as norepinephrine may be needed (choice E). However, fluid resuscitation must be continued.

    AND here i wud like to review certan things...........which wud help u anwer the qs...........

    LOW PCWP + LOW RAP: Blood loss, fluid loss, sepsis etc(anything which causes hypovolemia)
    LOW PCWP+HIGH RAP: Pulmonary embolism, Rt. ventricular infarct...
    HIGH PCWP+NORMAL RAP: LVF, MS.....
    HIGH PCWP+HIGH RAP:constrictive pericarditis/tamponade......

Share This Page