A rare case of pulmonary embolism in a Mt. Kilimanjaro recreational hiker: A case report with review of literature

Abstract

Pulmonary embolism is one of the rarest complications of high-altitude sickness that can coexist with high altitude pulmonary edema. The risk of developing this phenomenon increases significantly with prolonged stay in high altitudes especially above 5000 m. Given the fatality of the condition, early screening and management is crucial; however, there is no gold standard approach in diagnosis. A 44-year-old male, a Tanzanian tourist first time hiking Mt. Kilimanjaro developed difficulty in breathing on the 4th day of ascending on a route that takes 6 days to summit whereby he was saturating at 38% on room air at the height of 4775 m. He was admitted with the clinical diagnosis of high altitude pulmonary edema. However, in the course of treatment for 72 h with no improvement, further investigations including computed tomography scan were suggestive of pulmonary embolism whereby he was treated with full recovery. Pulmonary embolism case reports are increasingly rising with the difficult to notice among high altitude pulmonary edema patients given their presentation similarities. A high index of suspicion based on clinical examination and investigations should prompt a clinician to include or exclude it.

Introduction

High-altitude sickness is characterized by a triad of life-threatening disorders; acute mountain sickness, high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE). ¹ It happens because of the physiologic respiratory failure of the body to adapt the high-altitude environment. ² It affects individuals who ascend rapidly from low altitude to high altitude. ³ This phenomenon occurs at an altitude above 2500 m; the illness worsens with a longer stay of 2–4 days on the high altitude. ⁴

HAPE is non-cardiogenic pulmonary edema that occurs as a result of pronounced pulmonary vasoconstriction as one adapts to high-altitude hypoxic state. ⁵ It is the severe presentation of the high-altitude sickness. ⁶ Prolonged vasoconstriction leads to damaged blood vessels endothelium and production of free oxygen radicals, which can result in the accumulation of fluids in the lungs. ³

Pulmonary embolism (PE) is a rare entity but is increasingly noted in high-altitude sickness as it coexists with HAPE and can present with identical symptoms and signs of HAPE. ⁷ A number of studies have suggested that high altitude predisposes to thrombosis.^4,7–11 These have shed light on the pathogenesis of PE and HAPE at high altitude that these entities can coexist in one patient and early diagnosis and treatment may improve the outcome of the patient. Another study reported up to 30 times the risk of spontaneous vascular thrombosis on long-term stay at high altitude in Indian soldiers exposed above the altitude of 5000 m. ¹² This is explained by the increase in hypercoagulative state and in the long run in a prolonged stay in the high altitude develop hyperfibrinogenic state, which complicates the condition. ¹²

In light of the above evidences, consideration of PE as a diagnosis must be considered especially when HAPE symptoms and signs don’t improve within 48 hours of descent. Many approaches may be considered in diagnosing the condition; however, none of which is considered a gold standard. Chest tomography with angiography has been used mostly with the ability to show changes in the pulmonary vasculature.

Case report

We present the case report of a 44-year-old male, a Tanzanian tourist who was the first time hiking Mt. Kilimanjaro. He had no significant past medical history and had not used any prophylaxis before or during hiking the mountain. On the 4th day of ascending on a route that takes 6 days to summit, at the height of 4775 m, he developed severe difficulty in breathing. An initial assessment done by the professional guide reported he was breathlessness with sharp chest pain, weak pulse, and had low oxygen saturation of 38% in room air. He was immediately kept on oxygen and rapid descent was initiated by the guides using a customized single-wheel canvas bed to a level of 2300 m where there was a standby ambulance that shuttled him to a health facility. At the base of the mountain, the saturation raised to 83% on supplemental oxygen with mild improvement of the symptoms. There was no reported history of confusion, loss of consciousness, or fever.

At arrival to the hospital the patient was still dyspneic, afebrile, and on oxygen supplementation with saturation of 86% in room air. When titrating the oxygen level to 5 l of oxygen on rebreather face mask, saturation reached 98%. The rest of the vital signs were; BP: 130/77 mmHg, PR: 103 bpm, RR: 24 cycles/min, T: 36.7°C. Systemic examination of the chest revealed fine crepitation at the mid zone and base of the lungs on bilateral auscultation, and other systems were essentially normal.

The investigations done were chest X-ray, which showed bilateral lower lobe infiltrates more on the left lung features suggestive of pulmonary edema, electrocardiogram (ECG), which showed sinus tachycardia, and CBC, which showed normal leukocyte count with hemoglobin of 12.9 g/dl, hematocrit of 37%, and D-dimer raised to 8.5 UgFEU/ml, and other biochemistries including creatinine and lipid profile were all normal; however, COVID-19 wasn’t tested because it seemed unlikely. The patient was kept on oxygen and was also initiated on Nifedipine 10 mg orally twice a day. The patient was nursed in the ward.

On the 3rd day in the ward, the patient was still dyspneic and was still saturating at 91% in room air and 95% on 8 l of oxygen. An ECG was done again and showed features of right heart straining, an echocardiogram (ECHO) was done with normal findings, and chest CT angiography was ordered and revealed a filling defect in the right upper and bilateral lower lobe pulmonary arteries suggestive of PE (Figure 1). The patient was initiated on low molecular heparin (enoxaparin) 60 mg subcutaneously twice a day for 5 days and remarkably improved. While in the ward the coagulation profile at baseline was PTT-21s with INR at 0.95. Follow-up after 2 days revealed PTT of 23 s and INR of 1.54. He was discharged after 4 days with warfarin 5 mg orally once a day, and he was instructed to return back to the health facility after 2 weeks for follow-up visit. Unfortunately, the patient was lost to follow up.

Figure 1.

Computed tomography pulmonary angiography shows filling defects in the left main pulmonary artery, and segmental and sub-segmental branches of the right lower lobe pulmonary arteries suggestive of pulmonary embolism as shown by blue arrows. Bilateral lower lobe ground glass opacities predominantly in the left lower lobe suggestive of pulmonary edema as shown by red circles.

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 Kilimanjaro Christian Medical Centre-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 PE. ¹³ This shows there is a limited documentation and probably underdiagnoses on PE among HAPE patients.

Some of the risk factors for the 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, dehydration, and genetic underlying factors, for example, 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 hyperfibrinogenic state, which in terms escalates the formation of clots. ¹² The speed of ascend is also vital; consider rapid ascend when one ascends at a speed of 1000 m/day without rest. Normal international guideline suggests 300–400 m/day with 24 h rest on day 3–4 of ascent to reduce the risk of developing high-altitude sickness. The patient had already exposed to the risk factors of high altitude, cold environment, and prolonged stay in the high altitude (4 days).

The patient also presented with similar symptoms such as body weakness, chest pain, difficulty in breathing, and hypoxia as reported in other cases of 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 poor sensitivity can lead to false positive results. ¹² It has been found that D-dimer assay is highly sensitive but less specific, and it is an excellent screening test for PE 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 PE).

Confirmatory radiology test such as CT pulmonary angiogram 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 duration is almost the same to the ones reported in other similar cases management.^4,7,9

Conclusion

PE case reports are increasingly rising with the difficult to notice among HAPE patients given their presentation similarities. A high index of suspicion based on clinical examination and investigations should prompt a clinician to include or exclude it. Early diagnosis is the key especially if a patient is not improving despite the clinical measures taken for managing HAPE. However, further studies are needed to understand more on the occurrence of PE in high altitudes and the possible development of a screening tool that could assist in early diagnosis to prevent the development of serious complications.