[HSF]diagnosis of tamponade

[Rwmfglycar at aol.com]

In a message dated 12/6/2007 12:06:32 A.M. Eastern Standard Time,  
donross at bigpond.com writes:

Okay,
You left a tube in the pericardium during surgery to  enable   
tamponade diagnosis???
Not something that would be a  practical for routine surgery.
I also surmise that your catheter may not  necessarily give a  
representative reading if clots partitioned the  pericardial cavity.
The diagnosis of post-op tamponade is notoriously  elusive.
Does anyone believe there is a gold standard  test?
Don



Read the article. I was describing the pericardial drainage tube. If there  
was bleeding (virtually always there has been exceasive bleeding in a case 
where  tamponade occurs) the tube is still in. This test worked in the first 24 -  
48 hrs. 
Experimentally, if a heart is put into ventricular failure by doing  
something to the ventricle/s the pericardial pressure rises by only a small  amount 
even when the ventricle dilate and the enddiastolic/atrial pressures  rise 
considerably. When the pericardial pressure is progressively raised   in the 
presence of normal ventricles, the cardiac output drops when the  pericardial and 
atrial filling pressures equalize.
Yes there can be localised tamponade with a large clot  pressing on a  
crucial part of a ventricle (not atrium). Yes you  can construct a scenario  in 
which the left ventricle is in a pericardial compartment of its own due to a  
unique distribution of firmly adherent clot so that only the left ventricle has  
its filling compromised by fluid under pressure. This is unusual.
Yes the situation is confused by the simultaneous occurrence  of damaged 
ventricular function and pericardial fluid under pressure. It is  confused also by 
the way people jack up the inotropic and, worse, the  vasoconstrictor agents 
when the blood pressure is down.
Yes tamponade causes a reduction in subendocardial coronary flow and  damages 
normal ventricles. Time is critical when this is happening.
The pressure test I described  was developed in the pre echo  days. Good 
modern echo can sort some of these things out but its usefulness is  influenced by 
availability and operator understanding of the situation, operator  skill and 
the time taken by  you and the operator to reach a  diagnosis.
I don't need to tell you that if you are in doubt you make a hard  decision 
on soft evidence and open the chest with all the care  described in this thread 
. It is a very simple risk analysis.
The specific manoevre of opening of the lower end of a median  sternotomy 
incision to relieve tamponade has its major utility  in the  patient on the floor 
with all tubes out and still in the hospital because an  astute clinician has 
decided to defy the system and  keep the patient in  for another few days 
because of a slow recovery. A gush of  bloodstained fluid into the bed after 
cutting the lower rectus  sheath sutures works wonders.
The variables are too many for a single test to be a gold standard. The  gold 
standard for management and avoidance of death from tamponade resides in  the 
ability of the caregiver to analyse multiple findings and multiple possible  
risks at the same time.
 



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