Haemodynamic monitoring

Question 1

Discuss the uses of systolic, diastolic and MAP

Answer 1

Systolic pressure is important in patient with bleeding
Diastolic pressure is a good estimate of coronary perfusion and is important in patient with poor coronary flow

MAP is important measure of tissue perfusion and is important in patient in which organ perfusion may be compromised

Question 2

Discuss estimating fluid responsiveness with invasive blood pressure monitoring and mechanical ventilation

Answer 2

In patients that show a large degree of variability in systolic pressure between respiration are more likley to be responsive to fluid

Question 3

Discuss the usefullness of central venous pressure

Answer 3

More helpfull in determining cause of a problem then detecting one. Measures right ventricular pressure which equates to right ventricular end-disatolic pressure. Preload is more closely related to end-diastolic volume then pressure.

As compliance of ventricle is unknown a single reading is usually not helpful

But measuring the difference in pressure pre and post fluid bolus can given an idea if a patient is under, normo or over loaded
If there is a little change in EDP with a fluid bolus volume is likley to be low if there is a large change it is likley to be highg

5 minutes post a fluid bolus if EDP changes 0-3mmhg likely under filled if it is 3-5 likely adequate and more then 5 likely over filled

In general it is left preload which is over greater value and an assumption is made that R=L which is not always the case in ill patient with unilateral heart failure, valvular disease or sever pulmonary disease

Question 4

Discuss complication of Central line placement

Answer 4

infection 
bleeding 
pneumothorax 
inadvertent arterial puncture 
damage to adjacent structure 
lost of wire

Question 5

Discuss the use of pulse pressure variation in assessing fluid balance

Answer 5

if large difference in pulse pressure in different stage of ventilation indicate hypovolaemia

Large tidal volumes are needed > 10mls/kg

passive leg raise can be used as a reversible fluid challenge of approximately 500mls of blood if pulse pressure rises more then 10% suggest patient is hypovolaemic

Question 6

Discuss venous saturation monitoring

Answer 6

If tissue blood flow is inadequate to meet demands more o2 will be extracted from the arterial blod leading to reduce venous saturation

Targeting central venous saturation of >70% has been suggested by one study

Question 7

Discuss assessment of hypotensive patient

Answer 7

MAP == CO x TPR
CO =HR x SV
SV is dependent on preload, afterload and contractility

Both preload and contractility can be measured using echocardiographs

Question 8

Discuss cardiogenic shock

Answer 8

cardiogenic shock is due to pump failure resulting from myocardial or valvular failure. The strict diagnosis requires persistence of hypotension despite correction of hypovolaemia, hypoxia profound acidosis and arrythmia

In patient with cardiogenic shock due to myocaridal ishcaemic or infarction the two mainstays of treatment are to increase diastolic pressure and therefore coronary perfusion pressure and to increase cardiac output

Increasing coronary perfusion can be definitive or supportive
Definitive intervention include PCI and stenting or thrombolytics (this tend to be less affective in cardiogenic shock states)

Supportive care includes the use of norad as it increase diastolic pressure without increasing myocardial oxygen demand greatly
Judicious use of fluid in 100ml boluses may be used
It should be noted that increase right atrial pressure may be due to reduction in compliance rather then fluid overload
Careful administration of vasodilators in normotensive patient to reduce afterload and myocardial o2 demand
Use of dobutamine can be considered

Question 9

Discuss causes of cardiogenic shock

Answer 9

IHD
cardiomyopathy 
trauma 
infection 
LV outflow obstruction
--HOCM
--Aortic stenosis  
LV inflow obstruction 
--mitral stneosis 
--left atrial myxoma

Question 10

Discuss dobutamine

Answer 10

Racemic drug

levo: alpha agnoist with B affect (chronotropy)
dextro: B1 and 2 agonist with alpha antognism

Affects: chronotropy with vasodilation

Question 11

Discuss hypovolaemic shock

Answer 11

the primary abnormality is decreased preload and a subsequent decrease in stroke volume
The typical HD picture is hypotension, low venous pressure, peripheral vasoconstriction and tachycardia

It should be noted that once hypovolaemia has been treated distributive picture can take its place due to initial insult

Fluids resus should be with normal saline or hartmans
Blood if significant blood
excessive use of normal saline can lead to hyperchloraemic metabolic acidosis

Question 12

Discuss causes of hypovolaemic shock

Answer 12

Loss
–bleeding

third spacing

• -pancreatitis,
• • burns
• -bowel obstruction

Gi loss
–D and Vs

Renal

• DKA
• diabetes insipidus

Question 13

Discuss distributive shock

Answer 13

Caused by inappropriate vasodilation and increased permiability
Common causes are sepsis and anaphylaxis, less commonly neurogenic or acute adrenal insufficiency

Question 14

Discuss obstructive shock

Answer 14

Cardiac tamponade
tension pneumo
massive PE

Question 15

Discuss dopamine

Answer 15

Short acting with inotrope, chronotrope and vasoconstrictor effects
affect on splanchnic circulation unclear
increase urine output through a tubular effect without affecting creatine clearnace

Starting dose 5ug/kg/min

Question 16

Discuss supportive care in massive pulmonary embolus

Answer 16

Consists of fluid and vasoconstriction
large amounts of fluid resus should be avoided as a marked increase in right pressure can significant reduce coronary artery perfusion