Acute massive pulmonary embolism is a dreaded medical emergency . In the past, surgical embolectomy was the main option . Now , we have thrombolysis as a viable option.But , it does not work in all cases.* (90% success ?). It is critical to evaluate the success of thrombolyis , before embarking upon rescue embolectomy.
As it is often in critical care medicine , this decision making is not easy .
The key question is how long , we shall wait before labeling thrombolysis a failure !
In-fact , premature assessment is the commonest cause for failed thrombolysis. True failure is different from deemed to be a failure . This is often related to , lack of patience among the members of treating team . Unlike acute MI ,there is not a strict time window to follow .The issue hear is , not lung salvage but restoring VP/VQ and dead space ventilation . The assessment is made , by clinical , MDCT ,Echo parameters.
When there is difficulty in judging success , clinical parameters will prevail over medical images !
Key clinical parameters for monitoring
- Heart rate
- Saturation
- Blood pressure
There are four options available to manage in failed pulmonary thrombolysis.
1.Emergency embolectomy in an unstable patient *
2.Elective , planned embolectomy in a sable patient **
3.Repeat thrombolysis ***
4.Continue Intensive heparin regimen for up to a minimum of 72hours and up to a week .
* Dismal outcome .
** Best option (Ironically, these are the patients , who improve with medical management , as well !)
***This is especially useful when partial success is noted in a stable patient . ( For rescue thrombolysis it is logical tom use TPA if SK was used initially and vice versa.) The logic here is the initial dose was either insufficient or ineffective to lyse the thrombus completely. If TPA is not available /or not affordable, repeat SK can still be considered .It can be safely administered within the 5 days of initial dose.
**** Least popular and considered inferior but has worked wonders in many .
How to manage a relatively stable patient with a large thrombus load in his pulmonary artery ?
Option number 3 could be tried. Prolonged monitored heparin
What are the surgeons concern about management in failed pulmonary thromolysis ?
Every surgeon( Especially the cardiac surgeons) loves to operate in a stable patient . If you hand over a case for pulmonary embolectomy , with sinking O2 saturation and falling blood pressure ,the outcome can be easily predicted !
Further, RV dysfunction is notoriously known for pump dependency . CT surgeons are vastly experienced in the intra operative tips and tricks of managing LV dysfunction (They may not be in so in RV dysfunction !)
Bleeding risk is also high especially in the milieu of intensive anticoagualtion and thrombolysis .
The mortality could be as high as 30 % in many centers.
Final message
- The incidence of failed pulmonary thrombolysis is often subjected to the whims and fancies of treating physician and the imaging modalities used.
- Timing of assessment is critical .One need to give a long rope for medical management , in spite of the urge , to do something more. .
- Clinical improvement should be the main guiding force.
- Normalisation of tachycardia , improving trend of o2 saturation( >90-95%) , regressing RV size are useful parameters.
- Thrombus load detected by a repeat CT scan , need not be the sole guiding parameter.In -fact , mobilising these patients for CT scan by itself is fraught with a risk of worsening the hypoxia.
- The issue of tackling the source of thrombus should be addressed separately .Luckily, the same anticoagulant protocol takes care of this issue also. It is rarely a emergent issue.
- Deploying an IVC filter as an emergency procedure is a bigger controversy .At best , it is useful in few high risk individuals with high risk mobile ileo-femoral clots .
- Finally, not every one can handle this situation .Ideally such patients should be to be shifted to a well established cardiac surgical set up .
From Chest journal
http://chestjournal.chestpubs.org/content/129/4/1043.full.pdf+html
Dr.S.Venkatesan MD 