Todd Fraser on 29-12-2012
It seems that when it comes to weaning long-term patients from a ventilator, there are as many theories on how to do it as there are intensivists. And probably more.
Many methods have been put forward. Certainly, its important to address any reversible factors that contribute to weaning failure, the subject of our December vodcast. Issues with resistance, compliance, power, demand and sputum clearance, as well as unmasking borderling cardiac function, all appear important.
The best method though for successfully liberating patients from the ventilator is contentious. Progressive reduction in inspiratory pressure, utilising intermittant mandatory ventilation with decreasing mandatory frequency, and periods of "spontaneous ventilation" have been proposed, and all probably have their merits. Few studies exist, with conflicting results, though SIMV does not appear to be as good as other methods. Much of this is myred in definitional differences, with no consensus on the appropriate use of these methods.
An interesting paper has been released recently highlighting the impact of mechanical ventilation on diaphragmatic strength, and the results are frightening. Although small numbers, if the results are verified, the 6% loss of diaphragmatic thickness per day is likely to have major effects on weaning, and begins less than 48 hours after initiation of mechanical ventilation.
So what is the best method of "training" patients to come of ventilation?
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I dunno about the evidence, but my approach is a daily period of respiratory exercise - I set common sense parameters such as 20% increase in heart rate, 20% change in blood pressure, respiratory distress, rising CO2 etc, and let them go for it. My preference is for a T-piece on a humidified circuit. If they show any signs of getting tired, they go back to the vent. Try to extend each day until they can breathe without the vent for 24 hours.
Nice review of this topic - http://www.nexcob.nl/resources/ABC-weaning-failure.pdf
My practice is similar to Nathan's
I think that weaning a long-term Pt off the ventilator, is not only challenging and I also think that somewhere in this discussion besides talking about the parameters and ventilation modes and settings, people have been missing the most important part- the Patient going through the weaning process, as well as their Families. I personally believe that no long-term ventilated Adult or Child with Tracheostomy should stay longer than 60 days in Intensive Care. Why do I say this? Other countries, mainly in Europe(Germany, Austria, Switzerland, Netherlands) have adopted a far more effective, efficient and most importantly a far more Patient and Family focused practice as long as 15 years ago. The alternative for those long-term ventilated Adults or Children with Tracheostomy is to go home, looked after by Critical Care nurses. It's a no brainer in those countries. Why is it a no brainer?
I agree with Hutzel. The intensive care physicians and nursing staff can provide the care out of the icu environment when it is feasible and practical. This not only saves money but certainly helps preventing the nosocomial infections.