Discussion
The case above describes a complicated relationship between HAPE and PE. The prevalence among the climbers at Mt. Kilimanjaro is not known. However, with time, there is accumulation of evidences suggesting the increase in risk of developing PE with high altitude. The study done at KCMC-Northern zonal hospital in Tanzania on mountain sickness, among 62 participants (patients); 14% had Acute Mountain Sickness, 54% had HAPE, 12% had HACE and 20% reported to have combined HAPE/HACE, however, no documentation on the patient who had pulmonary embolism [13]. This shows there is a limited documentation and probably underdiagnoses on pulmonary embolism among HAPE patients.
Some of the risk factors for development of thrombosis phenomenon includes; the high altitude itself, the prolong stay in the high altitude, environmental condition with extreme cold, hypoxia, prolonged immobility, polycythemia and dehydration and genetic underlying factors e.g. factor V Leiden mutations contribute to the hypercoagulable state [14]. There is a transient raise in clotting factor noted in the first few weeks upon climbing. Upon acclimatizing it is expected to decrease in clotting factors however prolong stay in high altitudes causes hyper fibrinogenic state which in terms escalate formation of clots [12]. The speed of ascend is also vital consider rapid ascend when one ascends at a speed of 1000metres/day without rest. Normal international guideline suggests 300-400 meters/day with 24 hours’ rest on day 3 to 4 of ascent to reduce the risk of developing high altitude sickness. The patient had already exposed to risk factors of high altitude, cold environment and prolonged stay in the high altitude (4 days).
The patient also presented with similar symptoms like body weakness, chest pain, difficulty in breathing and hypoxia as reported in other cases of pulmonary embolism(PE) in high altitude [4,7,9]. Early diagnosis of PE in high altitude is very important given its high mortality however challenging in settings where pure HAPE is more likely among mountain climbers. D dimer can be an important screening tool given its positive predicting value as it was demonstrated from the case above which was found to be raised. In diagnosis of PE, one study showed D dimer to be positive in 96.2% of cases [14].
However, D-dimer can be raised in high attitude and other underline diseases and with is poor sensitivity can lead to false positive results [12]. It has been found that D-dimer assay is highly sensitive but less specific, it is an excellent screening test for pulmonary embolism with sensitivity of almost 100% and negative Predicting Value of 100% complemented by clinical findings from the patient [12]. It can help to rule out pulmonary thrombosis (Diagnosis of pulmonary embolism).
Confirmatory radiology test like CTPA could be done to confirm the diagnosis if suspected [14–16]. Hence in a resource limited area where radiological investigations are absent D dimer could be a useful screening tool for PE among mountain climbers presenting with HAPE.
The patient was treated and improved on oxygen and anticoagulants and discharged after 4 days. This approach and hospital stay days is almost similar to the ones reported in other similar cases management [4,7,9]