Mobile Computing in Military Ambulatory Care
Introduction
In recent time, users of portable computers such as palm-top computers are able to maintain their network connection while travelling from one place to another. A mobile network consists of a pre-existing static network that communicates with the mobile hosts via a wireless connection. As a mobile host is able to disconnect from the network, it poses problems for transaction management. This is because it must assure that the data it is using is valid and all the local updates are reflected in the database. Hence, data replication is the intentional storage of copies at multiple sites across a network to improve fault tolerance and data availability in case of a site failure. On the down side, data replication adds the overhead of maintaining consistency across multiple sites of the network. Mobile hosts that have the capability to store copies of data items increase the difficulty of data replication consistency because they are considered to be volatile storage and can be disconnected from the network for extended periods of time. Therefore, mobile replica management algorithm is introduced. The replica control algorithm that synchronizes the data replicas maintained at the mobile and static databases is coordinated by a mobile transaction manager (MTM). The MTM is responsible for the transaction initiated by mobile host to query and update the replicated databases. Since the mobile host is a volatile storage area, the "virtual primary copy" technique is used.
Environment
The battlefield medical is a unique and very different environment from the civilian medical environment.
The difference:
- the medics want to minimize the evacuations and movements of soldiers from the scene of the injury
- the databases of the mobile hosts, the base stations (and its agent), and the MASH units are susceptible to damage and disconnection due to enemy attacks
- the base station hardware must be transportable and easy to assemble
A battlefield is divided into 3 echelons which range from the actual combat zone to a hospital that is hundreds of miles away. Medical units are spread across the 3 echelons. As the echelon number increases, the proximity to the combat decreases. Medical telecommunication advances have allowed medical units to be stationed in remote and difficult environments.
In a proposal battlefield management environment, the mobile hosts are the mobile medical monitoring vehicles (M3V) equipped with computers and the field medics that carry Pro-Med, which is a Personal Digital Assistant (PDA). Besides, the soldiers positioned in the first echelon of the battlefield wear a Personal Status Monitor (PSM) that monitor the soldiers vital signs and provide geographical information via a wireless radio mechanism.
A Typical Wounded Soldier Scenario
When a soldier has been wounded, the PSM transmits a repetitive signal that contains the soldier’s signs and location. A medic with a Pro-Med or MV3 will response to the soldier’s signal. Then, the combat medics can start a transaction to query the patient-soldier database that resides on their own computer. The transaction, which is composed of read and write sub- transactions, queries information about the soldier’s medical history, current medications and allergies. Each medic has a partial copy of the patient-soldier database that resides on the static portion of the network.
The medic’s aim is to preserve critical organ function at minimal physiological status. This might require the medic to give the wounded soldier medication according to the soldier’s present medications and allergies that the transaction has returned from the network. When the soldier has been stabilized, the medic can place the soldier in a Critical Care Pod, which functions like a hospital intensive care unit, for long-range evacuation under controlled conditions. The medic creates another transaction to update the medical record of the wounded soldier. The transaction is composed of read and write sub-transactions that include the following:
- Description of the incident
- Symptoms and mechanism of injury
- Vital signs - BP, pulse, respiratory rate and general appearance
- Treatment rendered and response to that treatment.
The update to the database prepares the staff of the MASH, CSH and regional medical centers for the arrival of the wounded soldier in the case of an evacuation.
Architecture
The database for the architecture is a replicated distributed medical record system that provides an electronic patient-soldier database for the medical personnel from positions near the combat zone to rear-echelon support medical centers. The replicated Battlefield Electronic Patient Record (BEPR) contains the medical histories of all current military personnel. The BEPR ensures immediate continuity, distribution and accessibility of medical information from the forward battlefield positions (echelon 2) to the rear- echelon support (echelon 3) of the United States-based medical centers. Each mobile host (Pro-Med and M3V) contains a replica for the platoon of soldiers that are stationed in its area.
Conclusion
By providing the far-forward medics access to vital, consistent and critical patient data from any location on the battlefield, the medics can treat the soldier on the battlefield, which minimizes the evacuation/movement of injured soldiers from the battlefield. Replicating data on mobile computers increases the availability of patient’s record. When a mobile host updates a local replica, the changes made to the local copy need to be reflected in the rest of the replicas.
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