Wednesday, March 08, 2006

Focus on Pandemic Flu Treatment

The Department of Health and Human Services (HHS) has taken the lead in preparing the country for a potential pandemic. HHS goals include: tracking the global spread of the H5N1 influenza virus, early human detection, assisting with local preparation, increasing stockpiles of antiviral drugs, developing vaccines against potential pandemic virus strains, and enhance domestic vaccine production capacity.1 These goals illustrate HHS focus on early detection, containment, and prevention. However, in addition to these goals, a comprehensive plan should also include preparation for the grave complications associated with influenza infection.

During a moderate to severe flu pandemic, an estimated 20-50 % or 60-150 million people in the US would become infected. 1-10 % or 3-30 million would die from Acute Respiratory Distress Syndrome (ARDS). ARDS was and will be the most common complication and cause of death in pandemic flu patients. The 3-30 million expected to die will be in need of positive pressure ventilation. Sadly, the US only has 100,000 ventilators.2 ARDS is a deadly respiratory complication of pneumonia resulting in 50 % mortality with mechanical ventilation and 100 % mortality without it. That said; if ventilators could be provided to all 3-30 million people who would develop ARDS, 1.5-15 million lives could potentially be saved.

Stockpiling modern ventilators is an impossible proposition. Vents average between $10-50,000 each and are complex mechanical and electronic machinery.3 Although ventilators are complex, the functions of oxygenating and ventilating a patient are simpler processes that can be performed short-term with a bag and mask. The challenge is automating these processes.

Very little research has been done to address disaster-associated ventilator shortages. A PubMed search produced one article published in 1994 in Critical Care Medicine. This research group recognizes the inadequate surge capacity of the US healthcare system during catastrophes because of the lack of ventilators. Accordingly, they illustrate 2 novel ideas to mechanically ventilate multiple patients using one ventilator.4 Simple ideas like this could make a significant impact during a pandemic.

Aspects of additional research should involve a comprehensive literature search, and design and testing of simple ultra-cheap ventilator systems. These “mini-vents” could be more practically and economically mass-produced and stockpiled. Also, plans to “MacGyver” a ventilator using common “off-the-shelf” hospital and hardware store equipment could also be developed and tested.

One exciting idea involves an alternative form of mechanical ventilation used in very premature babies in the NICU called High Frequency Oscillatory Ventilation (HFOV).5 It turns out that portable ball/tire pumps work about the same as these HFOV machines but cost between $10-50 instead of $10-50,000. If proven feasible after testing, units could be stockpiled at a cost of $10/unit. Additional units could be procured by utilizing available stock at local hardware stores as needed. This idea could prove a substantial value in comparison to Tamiflu with costs $8/pill.

In association with mechanical ventilation, it is the generally accepted that patients who are expected to be mechanically ventilated for long periods of time such as is required to recover from ARDS, do better with a tracheotomy (tube in neck) rather than being intubated (tube in mouth). Also, tracheostomy tubes are associated with less ventilator-associated pneumonia (VAP). Patients who receive HFOV must be paralyzed and sedated. Paralytic medications, tracheostomy tubes, pressurized oxygen and broad-spectrum antibiotics to treat VAP will be in short supply and must also be stockpiled.

In addition to its current goals, HHS must focus on resolving the impending pandemic-associated ventilator shortage as well as develop goals to treat victims of pandemic flu as a part of its comprehensive plan. If a simple alternative to modern ventilators could be found, it could result in the biggest mortality benefit to those who will eventually become stricken with this deadly disease. These ideas could also be utilized in other disaster scenarios such as natural disaster, bioterrorism attack with nerve agent, and major industrial accidents.

1. News Release, Secretary Michael O. Leavitt, Department of Health and Human Services, Thursday, Jan. 5, 2006.

2. Osterholm, MT. Preparing for the Next Pandemic, NEJM. May, 2005 352:1839-1842.

3. Blanch, PB. An Evaluation of Ventilator Reliability, Respiratory Care. August 2001.

4. Sommer DD, Improvised automatic lung ventilation for unanticipated emergencies. Crit Care Med. 1994 Apr;22(4):705-9.

5. Ritacca et al. Clinical review: High-frequency oscillatory ventilation in adults. Critical Care. 2003, 7:385-390.

No comments: