Saturday, March 8, 2008

Review of - Positive-Pressure Ventilation Equipment for Mass Casualty Respiratory Failure

Today I will review the document “Positive-Pressure Ventilation Equipment for Mass Casualty Respiratory Failure”. This is available for free as html or PDF at
http://www.upmc-biosecurity.org/website/resources/publications/2006_orig-articles/2006-06-15-positivepressureventilationformasscasualtyrespfailure.html
The authors are: Lewis Rubinson, Richard D. Branson, Nicki Pesik, and Daniel Talmor

This document discusses the need for additional ventilators for a mass casualty event including an influenza pandemic. They discuss the need to stockpile additional ventilators for such an emergency. They also acknowledge that it would be very expensive to stockpile and maintain enough full-featured ventilators to be adequately prepared for such an event, so they discuss how positive pressure ventilators (PPVs) with fewer alarms and capabilities could also be used to supplement the existing stocks in time of emergency.

In my opinion, this is a very well researched and prepared article. Many of the issues documented in this article have in fact shaped the aims of the Pandemic Ventilator Project as well. It deals at length with the advantages and disadvantages of various types of ventilators for use in mass casualty respiratory failure. The emergency ventilators we are designing at the Pandemic Ventilator Project are not meant to compete with or replace regular commercial ventilators, but are meant as a backup in case authorities do not stockpile adequate numbers ahead of time.

The use of improvised ventilator equipment during the polio epidemic in Copenhagen in 1952 is discussed. They had only 4 devices available, but had to ventilate as many as 70 persons at a time. They designed and built a number of devices that were manually operated by medical students and saved many lives that would otherwise have been lost. This is a great example that innovative ideas, methods and pragmatic thinking can be used in times of crisis to save lives.

(For additional information on the use of alternative ventilators in the Polio epidemic, see my previous post http://panvent.blogspot.com/2008/01/everything-old-is-new-again.html )

They then discuss how the use of PPVs requires highly trained and skilled health professionals, and that even in normal times, the number of skilled professionals and equipment is sometimes in short supply. In addition to increasing the physical supply of PPVs, there will also have to be plans in place to be able to extend the capabilities of the health care professionals. There is a discussion of different ways to stretch the existing supply of ventilators. There are details of various disaster scenarios and how they will affect the need for PVPs.

They give a good overview of the logistics of ventilator stockpiling and airway management. Endotracheal intubation is preferred. There is a chart that details the various types of alternative Ventilators and their characteristics. The text provides a detailed analysis of the advantages and disadvantages of each type.

They then reiterate the expected shortage:
“Even with significant state and regional investments in PPV caches, there will likely be a shortage of available PPV equipment during a severe influenza pandemic. Standardized approaches to prioritize allocation of scarce resources such as ventilators must be considered for such events.”

They close with this ominous statement:
“Even though not enough PPVs could be stockpiled to ensure that each patient with ARF has a ventilator during a severe influenza pandemic, the additional capacity afforded by reasonably sized caches can help a significant number of patients survive. This additional PPV equipment must be purchased within the context of a rigorously developed strategy to provide a coordinated medical response to catastrophes. Without such equipment, many patients may die despite having survivable clinical conditions.”

The Pandemic Ventilator Project exists to supply a design for a ventilator that can be built from readily available components to fill that last shortfall. I wonder what the writers of this document think of the Pandemic Ventilator Project? I wonder if they are even aware of it? This document was written nine months before the Pandemic Ventilator Project was started. They cite the use of jury-rigged ventilators constructed during the polio epidemic in Copenhagen as an example of how lives can be saved by using alternative ventilators, but then they recommend that only FDA approved devices be used. In fairness, I do not see how any planner working under the existing liability framework can recommend anything other than an FDA approved device. It is only when an actual crisis arrives, when they are faced with triaging the available ventilators to do the greatest good for the greatest number of people that real alternative solutions can be considered.

1 comment:

Alec Lenz said...

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