First Aid for Gunshot Wounds in High Altitude Areas
Introduction: We will discuss special prehospital treatment of the mass numbers of victims of firearms that had not been considered previously. Since 1990, we have attended to the research work of gunshot wounds in such area as Xi Zang, where the plateau is about 4,000 meters (13,123 feet) above sea level (mean atmospheric pressure = 463 mmHg, pO2 = 97 mmHg), We received 574 victims and their wound location, type, and result (died of wound or killed in action) are shown in Table 1.
Table 1-Number and percentage of gunshot wounds by location, type and result
Non-
Anatomical Penetrating Penetrating
Location Wound Wound_
N (%) N (%)
Head 35 (6.0) 62 10.7
Chest 25 (4.3) 66 11.4
Abdomen 26 (4.5) 43 7.4
Perineum 5 0.9 11 1.9
Upper Extremity 48 (8.3) 70 12.1
Lower Extremity 45 (7.8) 90 15.6
Other 23 (3.9) 48 8.3
Total 184 (32.0) 342 (59.1)
Died Killed Number
Anatomical of in of
Location Wound Action Cases
N (%) N (%) N (%)
Head 4 (0.7) 58 (10.1) 97 (16.8)
Chest 3 (0.5) 64 (11.1) 91 (15.8)
Abdomen 8 (1.4) 44 (7.6) 69 (12.0)
Perineum 5 (0.9) 16 (2.8)
Upper Extremity 2 (0.3) 5 (0.9) 118 (20.5)
Lower Extremity 8 (1.4) 18 (3.1) 135 (23.4)
Other
Total 25 (4.4) 217 (37.6) 574 (100.0)
Effect of Topography and Climate: The high altitude climate of Xi Zang is varied and its topography consists of immense forests, precipitous cliffs, and deep valleys so that travel over the mountains is dangerous. Every year, between spring and summer, mountain floods, falling rocks or rock slides, and avalanches usually occur there. The communications in this area often have been interrupted by these calamities. The field hospital is located far away (about 600 to 800 kilometers) from the calamitous area. Therefore, it is very difficult to have the wounded transported to the field hospital and given first aid treatment. Statistics show that only 18.7% of the wounded can be transported to the field hospital within 24 hours.
Table 2-Effects of altitude
Research Altitude Altitude Barometric pO2
area (meters) (feet) Pressure (mmHg)
(mmHg)
3,175 10,417 500.5 104.90
Ton 5,110 16,765 400.5 83.84
Hang 4,366 14,324 439.0 92.0
Don 4,280 14,024 446.0 93.48
Pathophysiology Character and Clinical Signs of Wounds at High Altitude: The adverse circumstances with harsh climates at low atmospheric pressure cause pulmonary artery hypertension, low capacity of lungs, hypoxemia, and overload of the right heart. As a result, pulmonary edema appears. At sea level, the percentage of oxygen in the atmosphere is 20.95% and the pO2 at sea level is 159.2 mmHg. At an altitude of 10,000 feet (3,048 meters), where the barometric pressure is 523 mmHg, the percentage of oxygenremains 20,95%, but the pO2 decreases to 109.6 mmHg (pO2 = 20.95% X 523 mmHg = 109.6 mmHg).
The main clinical appearance of victims are due to hypoxemia. It is caused by an inadequate pO2 in inspired air and a ventilation defect with the result of in an oxygen deficiency in the tissues. The condition of victims is usually serious due to a majority of them presenting with penetrating wounds. Penetrating wounds cause this form of hypoxia with blood loss and anemia. The initial respiratory system response to hypoxia in the wounded, is an increased rate and depth of ventilation. Hyperventilation results in reduction of pCO2 causing respiratory alkalosis and a shift of the oxyhemoglobin association curve to the left. The result allows an increased binding of oxygen with hemoglobin for transport to the tissue.
At an altitude of 20,000 feet (6,096 meters), the oxygen saturation of the hemoglobin, drops to 70%, and the physical findings include an inability to remain upright, jerking of upper limbs, seizures, unconsciousness, coma, and death. For these reasons, then, the general condition of the wounded is quite serious.
Character of Wound Ballistics: The character of wound ballistics of casualties in the High Altitude area is related to the high percentage of cases with penetration. Thus, the number of patients with penetrating wounds occupy 54.1% of the total number of casualties. While the proportion of penetrating wounds reached 70% of the killed in action (KIA), the entrance of ballistics is small and exits large, the wound will be combined with serious edema and contamination. In bacteriological examination of wound ballistics at an early stage, staphylococcus aureus generally will be found. Low atmospheric pressure and pO2 make the anaerobic bacteria grow and propagate rapidly. Therefore, the incidence of gas gangrene rate increased to 3.4% (0.44% in Korean War).
Treatment: The natural state of high altitude is perilous. The statistics of our groups are self-explanatory and the self-aid of the wounded is only 9.6% (21.2% in Korean War).
Supplemental Oxygen: The effects to treat hypoxia of the wounded at high altitude is the goal of oxygen therapy, which increases the alveolar concentration of oxygen and decreases myocardial work.
Table 3—The effects of 100% oxygen inhalation at altitude
Altitude Altitude pO2 Post 100%
(feet) (meters) (mmHg) Oxygen inhalation
pO2 (mmHg)
36,000 10,930 39.4 170.9
42,000 12,802 26.8 128.3
46,000 14,021 22.2 105.9
Low Altitude Therapy: For this reason, to utilize high technological communication and helicopters to carry the wounded in the high altitude area is preferable to the original transportation means, is not limited by varied topography, and can conveniently transport the wounded to hospitals at lower altitude. The wounded can be resuscitated in a timely manner and complications from altitude stress and mountain hypoxemia can be decreased to a great extent.
Key words: altitude; ballistics; gangrene; gunshots; helicopters; hypoxemia; hypoxia; oxygen; penetration; prehospital; saturation; transportation; wounds
Prehosp Disast Med 2001;16(2):s90.
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