Vol. 18 • Issue 4 • Page 12
Ventilation Today
As you complete your post-therapy assessment of a child with asthma, the hospital administrator announces that an accident occurred at Polygon Chemical and Plastics, approximately 12 miles from your hospital.
An airborne vapor plume of pneumotoxicants is impinging upon several schools, area businesses, and residential neighborhoods, and extending onto a major highway. Several commuters and pedestrians have been exposed to the airborne chemicals, some losing consciousness due to hypoxia. The county emergency management authority declares a mass casualty incident and advises residents and building occupants to shelter-in-place.
Your hospital implements its external disaster plan. Patients begin to arrive at the hospital emergency department with varying degrees of respiratory distress, ocular irritation, and traumatic injuries resulting from secondary motor vehicle collisions, stampedes, and falls. Local emergency medical technicians are en route with several immediate patients on high-flow oxygen, others have been field-intubated, and still others are receiving oxygen and bronchodilators.
Several hours later, many patients arrive via ambulances and private vehicles exhibiting latent onset non-cardiogenic pulmonary edema and severe obstructive airway disease. Your hospital’s oxygen resources are dwindling, and re-supply has been delayed.
The realities of response
As may be evident by the preceding scenario, supplemental oxygen for normobaric oxygen therapy, resuscitative needs, inter- and intra-facility transports, and positive pressure ventilation remains a primary and critical component of health care system response to high impact, high consequence events.
Therefore, the provision of viable and sustainable oxygen supply and distribution systems is of paramount importance in medical planning and preparedness efforts. Natural and man-made events can disable and disrupt the chain of oxygen production, distribution, maintenance, and delivery of oxygen supplies to hospitals and home care patients. It is important to note that the Nation’s Strategic National Stockpile does not provide medical gas capabilities.
In addition, mass casualties generated from an incident or event can quickly overwhelm existing critical medical infrastructure. High acuity patients will likely require high volume supplemental oxygen and varying levels of critical care, including positive pressure ventilation, which would increase oxygen consumption. Depending on the type, scope, magnitude, and severity of an incident or event, oxygen resources could become severely disrupted and rapidly depleted.
Local health care facilities must maintain a self-reliant posture, including critical medical infrastructure, for up to 96 hours, as per recent Joint Commission guidelines. While challenging, resource allocation may remain manageable in localized incidents or events, even those requiring mutual aid from a nearby jurisdiction. The key is to plan ahead.
Assessing preparedness plans
Just-in-time planning is never as effective as advance preparedness efforts. Review your community’s hazard vulnerability assessment and the U.S. Department of Homeland Security National Planning Scenarios to prioritize threats and generate a reliable medical threat assessment for your health care institution and community.
Next, conduct a baseline assessment of your facility’s current capabilities within a high volume usage context. This includes a comprehensive review of your facility’s physical plant with your health care facility manager and disaster/emergency management coordinators in tow. The physical security and safety of medical gas supply and distribution systems, at all levels, must be addressed and assured.
Consider your facility’s usual sources of medical oxygen, and then integrate main and alternate gas suppliers into your comprehensive emergency management plan. Compressed and cryogenic gas suppliers and durable medical equipment companies must become involved in your preparedness processes. Inquire about the suppliers’ business continuity and emergency operations plans and their ability to provide services in mass casualty events and austere medical settings.
Investigate which systems they have available to augment traditional bulk delivery systems. For example, suppliers may be able to provide large capacity oxygen concentrators, but these devices depend on electrical sources for operation, which may be disrupted during an event. In addition, some hospital engineering safety regulations may prohibit their use.
Equipment paradigms
Next, you will need to determine which oxygen systems you should procure. Each equipment paradigm and potential solution has advantages and disadvantages, so RC managers must research all the possibilities. Economics invariably will play a role. A deployable, high technology oxygen generation or liquid oxygen storage distribution system would cost upwards of $480,000.
The most promising options for provision of supplemental oxygen may be a bank of 10 LPM home fill units or a rack of eight interconnected “H” cylinders, each supplying 7,000 L of oxygen for a cost of approximately $13,000. What the RC manager may not immediately realize is that the rack paradigm may sustain only 50 patients at 2 LPM for eight hours. This scheme would require three refills per 24-hour period. Patients requiring higher flow rates/FiO2or positive pressure ventilation would increase gas consumption and demand. Moreover, in an alternate care setting, this setup would require the timely installation of a gas distribution system, in addition to the logistical challenges of sustainability.
In the traditional health care facility setting, cafeterias or auditoriums may be converted to impromptu patient care sites. In this paradigm, portable oxygen delivery manifolds may be incorporated into a pre-fabricated or rapidly assembled arrangement of large cylinders, regulators, flow meters, and high pressure hoses to provide oxygen in mass casualty events. The use of oxygen blenders and other FiO2specific oxygen administration strategies also are crucial.
High pressure cylinders are available that can be pressurized up to 3,000 psi, which can increase the available oxygen capacity of an “E” cylinder from approximately 650 L to around 1,000 L. This will require regulators to accommodate the higher pressure. The use of integrated cylinder systems using a combined valve, regulator, and flow meter arrangement is highly recommended in mass casualty event environments to reduce hazards when changing oxygen regulators.
Having cylinders delivered with regulators may be another option and will serve as a “force multiplier” once the manager combines this supply with regulators already available, in the event that the department receives additional portable cylinders from vendor sources.
Utilizing a manifold system attached to a bank of high capacity “H” or “K” cylinders to “backfill” and supply oxygen via a bulk source system is a possibility. Oxygen-generating systems that range from trailer-based to fixed systems can produce several thousand cubic feet per hour of oxygen, which can supply wall systems and refill cylinders.
The conversion of nitrogen tankers to oxygen is another outside-the-box approach to oxygen resource management in high-impact, high-consequence events. This method would assist in portable liquid oxygen delivery to health care facilities.
Many possible solutions exist for oxygen resource management in mass casualty events affecting traditional and alternative health care delivery systems. No standardized policy exists yet that can be applied uniformly across all contingencies and communities. This is an area of opportunity for health care decision-makers at all levels.
For a list of references, look under the “Magazine” tab at www.advanceweb.com/respmanager.
Frank G. Rando is a consultant and educator in tactical, special operations, and disaster medicine, crisis and disaster management, hazardous materials toxicology, and emergency responses. He is affiliated with Homeland Security Programs and the University of Arizona Health Sciences Center-Arizona Emergency Medicine Research Center. He can be reached at [email protected].
Put to the test
Clinicians must use excellent history and physical assessment skills in mass casualty events. Resource allocation based on sound triage principles and guidelines cannot be overemphasized.
For example, the judicious use of pulse oximetry to triage patients and titrate or discontinue oxygen usage is of paramount importance. Yet, clinicians must remember standard pulse oximetry is unreliable in carbon monoxide or cyanide toxicity and should be confirmed by arterial blood gases or pulse CO-oximetry.
Weaning protocols for ventilated patients should be modified to facilitate spontaneous breathing trials and conversion from continuous aerosols to heat and moisture exchangers with low-flow oxygen to sustain targeted oxygen saturation. In general, by reducing oxygen flows and targeting oxygen saturation at 90 to 92 percent, rather than greater than 95 percent, both cylinder and bulk oxygen resources could be extended.
Another way to conserve oxygen: All clinical staff must make a concerted effort to recognize and correct avoidable gas loss from wall sources, flow meters, and manual resuscitators.
-Frank Rando
