Biological warfare (BW) aerosol attacks are different from chemical attacks in that they may provide no warning/all clear signals that allow the soldier to put on or remove his M17/M40 protective mask. Methods are now being perfected to detect a BW aerosol cloud using an airborne (helicopter) pulsed laser system to scan the lower altitudes upwind from a troop concentration of corps size, and to sample and analyze the nature of the aerosol within a brief time interval. This system has certain limitations and vulnerabilities, since it is designed specifically to detect a line-type aerosol attack. Provision of, training with, and field use of a lightweight dust mist or HEPA filter respirator for each soldier is proposed for protection against undetected aerosol attacks. This particulate filter respirator would be issued in addition to the M17/M40 mask. Such a BW respirator will be able to purify the soldier's air by removing particles in the 0.3- to 15-micro m-diameter range with an efficiency of 98 to 100%. Particle size of BW aerosols is in the same range, with an optimum size for high-efficiency casualty production of 1 to 5 micro m mass median diameter. The proposed BW respirator will be lightweight; will require low inhalation pressures; will be comfortable to wear for prolonged periods; will not interfere with vision, hearing, and communication; and will not degrade overall effectiveness and performance to the degree observed with the M17/M40 masks. Such respirators would be worn as part of a contingency defense against an enemy likely to use BW agents. This respirator could be worn for prolonged periods when under threat of an undetectable BW attack during weather conditions favorable to the success of such an attack (i.e., low wind velocity and temperature inversion in the target area). In addition, tactically important assets such as command and control centers and missile batteries can also be protected continuously by air filtration systems powered by electricity (modular collective protection equipment). Vaccinations against anthrax, botulism, Q fever, plague, and tularemia are now available and immune protection against ricin and staphylococcal toxins appears feasible in the near future. Chemotherapy can also be provided for prophylaxis of infectious agents released on the battlefield. The vaccines and antibiotics can provide back-up protection against an unexpected BW attack during a period when the BW respirator is not in use or malfunctions due to a poor seal or filter leak. Enemy sites of biological weapon production, assembly, testing, and storage, and delivery vehicles can be targeted for destruction by bombs and/or missiles. An integrated, well-planned, BW defense with multiple components can decrease the likelihood of a successful enemy BW aerosol attack.

The diagnostic usefulness of the medical history may depend on the type of problem confronted. It has been suggested that dyspnea is an example of a condition the causes of which cannot be easily distinguished based on identification in the history of stereotypical disease patterns presented in standard texts. To evaluate this assertion, faculty members independently interviewed 146 consecutively admitted patients with dyspnea, and following the history of the present illness, made a diagnosis. After discharge of the patients, another faculty member, using preselected criteria, independently reviewed each record to make a final diagnosis. History-based diagnoses predicted final diagnoses 74% of the time. Therefore, the history appeared to be useful in identifying the primary diagnosis for most dyspneic patients admitted to the hospital. However, it is not known whether this identification provides sufficient rationale for therapy or leads to more efficient use of laboratory tests.

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We evaluated the effects of a large (920 cal) liquid carbohydrate (CHO) load on the maximum exercise capacity of 18 patients with chronic airflow obstruction [forced expiratory volume at at 1 s (FEV1) = 1.27 +/- 0.48 liters; FEV1/forced vital capacity = 0.41 +/- 0.11]. Patients underwent duplicate incremental cycle ergometer exercise tests to a symptom-limited maximum following CHO and a liquid placebo in single-blind fashion. Expired gas measurements were obtained during each power output. In 12 patients arterial blood gases were measured, and in six patients venous blood was obtained for measurement of glucose, electrolytes, and osmolality. With CHO, the maximum power output decreased from 86 +/- 30 to 76 +/- 31 W (P less than 0.001), whereas the ventilation at exhaustion was nearly identical (47.6 +/- 13.2 and 46.8 +/- 12.5 l/min). Arterial partial pressure of CO2 (PaCO2) at exhaustion decreased (P less than 0.025), arterial partial pressure of O2 (PaO2) increased (P less than 0.01), and the ventilatory equivalent for CO2 (VE/VCO2) increased (P less than 0.005) with CHO. At equivalent power outputs, CHO resulted in significant increases in VE (P less than 0.001) and VCO2 (P less than 0.001); PaCO2 was unchanged, whereas PaO2 increased (P less than 0.01). CHO increased the serum glucose at rest and during exercise. No changes in serum osmolality or electrolytes occurred during exercise following CHO. After CHO loading, the majority of patients appeared to reach their limiting level of ventilation at a lower power output. In contrast, there was no significant difference in the mean maximum power output with CHO in six normal control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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