Poor Knowledge of Acute Mountain Sickness in Latin American Medical Students

Abstract

Introduction

Acute altitude exposure is a common event in Latin America that can result in mild to severe altitude illness. Medical students from some Latin American countries receive little information on this topic. Our aim was to determine the knowledge and incidence of acute mountain sickness (AMS), as well as the methods used to prevent AMS among medical students attending the Pan-American Student Meeting in Cusco, Peru, a city at high altitude (3400 m).

Methods

We conducted a cross-sectional study on medical students attending a conference. Participants completed a questionnaire on the day of registration that collected demographic data and investigated students’ knowledge of AMS, its prophylaxis, and their personal experience of symptoms.

Results

A total of 840 students attended the meeting. Two hundred eighty-eight returned surveys, 51 from high altitude locations. Respondent age was 23±3 y (mean±SD), and 72% were female. Thirty-two percent had basic knowledge about symptoms of AMS. Headache was recognized as a symptom by 79%. Knowledge of AMS prophylaxis was reported by 70%. Coca leaf products and dimenhydrinate were mentioned by 30 and 16%, respectively, whereas acetazolamide was recognized by only 10% of participants. AMS incidence was 42%. Prophylactic measures were adopted by 47% of the participants in our study. Thirty-six percent used dimenhydrinate and 27% used coca tea. Less than 1% used acetazolamide as recommended.

Conclusions

We found poor knowledge of AMS and effective prophylaxis among medical students from several South American countries traveling to 3400 m.

Introduction

In Latin America, nearly a quarter of the population lives at altitudes above 2500 m. ¹ Each year, millions of people travel to high altitude regions for purposes such as mountaineering, tourism, business, and religious pilgrimages.^2,3 Latin American physicians should be familiar with acute mountain sickness (AMS). Cities such as La Paz, Bolivia (3650 m); Quito, Ecuador (2850 m); Bogota, Colombia (2640 m); and Cusco, Peru (3400 m) regularly host medical student conferences at which participants are exposed to high altitude. AMS can interfere with social, recreational, and scientific activities.^4,5

AMS is a set of nonspecific symptoms, found in nonacclimatized individuals after rapid ascent to altitudes over 2500 m. ^{6 -8} The diagnosis of AMS is based on clinical features. The presence of headache is required for the diagnosis of AMS. Other symptoms may include nausea, vomiting, loss of appetite, fatigue, lightheadedness, and weakness. ^{9 -13} AMS occurs in up to 25% of nonacclimatized people who ascend rapidly to 3500 m. ¹⁴ Symptoms most commonly begin within 6 to 12 h of arriving at high altitude.^12,15

There are ways of reducing the risk of AMS, such as gradual ascent and use of prophylactic medication (acetazolamide and dexamethasone).^6,16,17 The aim of this study was to determine the incidence of AMS and the methods used to prevent it among medical students attending the Pan-American Medical Student Scientific Meeting in Cusco, Peru.

The organizers of the conference provided no information to participants regarding the symptoms or prevention of AMS before the event or on arrival in Cusco.

Methods

Our study was approved by the organizing committee of the Pan-American Medical Student Scientific Meeting.

We conducted a cross-sectional descriptive study, with data collected using a questionnaire (Table 1). We invited all students attending the meeting in Cusco, Peru, in 2018 to participate voluntarily and anonymously. We conducted the survey on the day of registration and handed the questionnaires to respondents. They were given time to fill in their answers and hand back the completed questionnaires. We developed the 14-item questionnaire after a literature review and discussion among the authors, in consultation with an expert in high altitude medicine.^18,19 No incentives were offered for participation.

Table 1

Survey questions about acute mountain sickness using respondents per questions as denominator

Demographic data and survey questions	Absolute count	Relative frequency
	(n)	(%)
Age (n=288) (mean±SD), y	23±3
Sex (n=288)
Female	207	72
Male	81	28
Place of residence (n=288)
Lima	74	26
Asunción	20	7
Arequipa	19	7
Cusco	18	6
Piura	17	6
Others	140	49
Year of medical school (n=288)
Fourth year	82	28
Fifth year	81	28
Third year	48	17
Sixth year	23	8
Second year	22	8
Other	32	11
University (n=288)
Universidad Ricardo Palma	31	11
Universidad Nacional de San Antonio Abad del Cusco	16	6
Universidad Católica de Santa María	15	5
Universidad Nacional Mayor de San Marcos	14	5
Universidad Nacional de Asunción	13	5
Other	199	69
Have you ever been above 2500 m? (n=237)
Yes	208	88
No	24	10
Unsure	5	2
Do you know the acute mountain sickness symptoms? (n=288)
Yes	257	89
If your answer is yes, which ones? a
Headache	203	79
Nausea	141	55
Lightheadedness	109	42
Vomiting	103	40
Dyspnea	71	28
Tiredness/Fatigue/Weakness	31	12
Dizziness	16	6
General discomfort/Malaise	14	5
Tachycardia	12	5
Other	109	42
Can your health get seriously compromised by acute mountain sickness complications? (n=237)
Yes	167	70
No	33	14
Unsure	37	16
Have you ever experienced acute mountain sickness? (n=237)
Yes	146	62
No	86	36
Unsure	5	2
Have you felt any of the symptoms below upon your arrival to Cusco? a (n=237)
Headache	126	53
Weakness/Fatigue	91	38
Nausea/Vomiting/Loss of appetite	70	30
Dizziness/Lightheadedness	53	22
Difficulty sleeping	43	18
Loss of balance	25	11
Mental confusion	13	6
None	58	25
Can acute mountain sickness be prevented? (n=237)
Yes	184	78
No	18	7
Unsure	35	15
Do you know any preventive measures for acute mountain sickness? (n=237)
Yes	166	70
If your answer is yes, which ones? a
Nonpharmacological measures
Acclimatization	16	10
Modifying diet	7	4
Adequate hydration	6	4
Others	15	9
Pharmacological measures
Coca leaf products	49	30
Dimenhydrinate	27	16
Acetazolamide	17	10
Other	114	69
Have you used any measure (eg, action, medication) to prevent acute mountain sickness? (n=237)
Yes	111	47
If your answer is yes, which one? a
Dimenhydrinate	40	36
Coca tea	30	27
Sorojchi pills b	24	22
Acetazolamide	6	5
Other	28	25
When did you start the preventive measure? (n=111)
1 h before the trip	12	11
2 h before the trip	8	7
3 h before the trip	6	5
24 h before the trip	2	2
Other	15	14
During the trip	34	31
Upon arrival	34	31

a

There could be more than 1 answer.

b

Combination of acetylsalicylic acid, acetaminophen, and caffeine.

The questionnaire (Table 1) consisted of 2 parts. The first part included demographic data, age, sex, place of residence, and information about university of origin and year of medical school. The second part evaluated knowledge of symptoms and prevention of AMS and personal experience of symptoms. For analysis of AMS prophylaxis, we grouped responses into 2 categories: pharmacologic and nonpharmacologic. Regarding acetazolamide, we classified use as appropriate if it was started at least 24 h before ascent at a dose of 125 mg every 12 h. Respondents were described as demonstrating at least a basic knowledge of AMS if they identified symptoms of AMS as headache and at least 2 of the following: fatigue, dizziness, and nausea. ¹⁹

We diagnosed AMS in participants living below 2500 m based on the Lake Louise AMS scoring system of 2018 as headache plus at least 1 of the following symptoms: gastrointestinal (loss of appetite, nausea, or vomiting), weakness and/or fatigue, and lightheadedness and/or dizziness.^13,20,21 Some items in the questionnaire allowed more than 1 answer (eg, symptoms that respondents identified with AMS could be headache or headache and dizziness).

For the analysis, demographic data and knowledge of AMS symptoms included all participants. For the analysis of symptoms and prophylaxis of AMS and the remainder of questions, only respondents traveling from locations below 2500 m were included. Data were analyzed using Microsoft Excel spreadsheets. Data are depicted as mean±SD, proportions, and percentages.

Results

There were 840 students who attended the meeting. Two hundred eighty-eight (34%) returned the questionnaire. Respondent age was 23±3 years, and 72% were female. Of respondents, 237 (82%) were students traveling from locations below 2500 m, and 51 (18%) lived above 2500 m.

Peru, Paraguay, Brazil, Bolivia, Colombia, Panama, Mexico, and Honduras were represented. Peru was the country with the largest number of respondents (74%), followed by Paraguay (11%) and Brazil (4%). A total of 48 universities were included. Twenty-nine percent of students were in their fourth year and 25% were in their fifth.

Among respondents, 208 (88%) had previously been to high altitude, 24 (10%) had never been to high altitude, and 5 (3%) did not answer. A total of 106 (62%) reported having had AMS previously, 86 (36%) denied previous AMS, and 5 did not answer.

Most students (257 of 288) claimed to have knowledge of AMS symptoms. Headache was the most frequently identified symptom of AMS, followed by nausea, lightheadedness, and vomiting (Table 1). We found that 24% of respondents living above 2500 m and 28% of those living below 2500 m had at least basic knowledge of AMS.

Students were asked about the possible impact of AMS on general well-being. One hundred sixty-seven respondents (70%) answered that AMS could seriously affect health (ie, could lead to serious complications, hospitalization, or death), 33 (14%) students denied such health impact, and 37 (16%) interviewees did not know.

Fifty-eight (25%) students reported having no symptoms, 74 (31%) reported having symptoms that did not meet our criteria for AMS, and 99 (42%) had symptoms that met our criteria for AMS (Table 1).

One hundred sixty-six respondents (70%) said that they had knowledge about prophylactic measures against AMS. We grouped responses into 2 categories: nonpharmacologic and pharmacologic (Table 1). Among the nonpharmacologic measures, acclimatization was the most frequently reported, mentioned by 16 respondents (10%). Seven respondents (4%) mentioned “modifying diet.” The most commonly mentioned pharmacologic intervention was coca leaf products (n=27 [16%]). Seventeen respondents (10%) identified acetazolamide as a prophylactic medication.

Use of prophylactic measures was reported by 111 respondents who traveled from locations below 2500 m (Table 1). Adequate hydration was reported by 2 (2%) students among the nonpharmacologic category. The most commonly used drug was dimenhydrinate, reported by 40 respondents (36%), whereas only 6 (5%) were taking acetazolamide. Of the 6 students who were using acetazolamide, only 2 of them started using it before the trip.

Discussion

In our study, the level of knowledge of AMS was low. This is surprising because respondents were medical students. We expected students living above 2500 m to be more aware of AMS; however, we found that only a quarter had basic knowledge of AMS. A similarly low level of knowledge was reported in a survey of experienced climbers. ¹⁸ Our finding that headache was the most recognized symptom was consistent with previous surveys of trekkers and tourists.^18,19,22 The incidence of AMS in our survey was 42%, consistent with the 38 to 45% reported in other studies in which participants ascended above 3500 m.^23,24

The Wilderness Medical Society guidelines ²⁵ and a recent Cochrane review ²⁶ recommend that acetazolamide, taken prophylactically, should be started 24 h before ascending. Eighty percent of the respondents claimed to know how to prevent AMS, but the measures they mentioned, such as adequate hydration, coca leaf products, and dimenhydrinate, were not in accordance with current recommendations.

Nonpharmacologic measures can be used to prevent AMS. The most effective nonpharmacologic method to prevent AMS is gradual ascent to allow time for acclimatization. Few of our respondents mentioned “acclimatization.” Respondents also mentioned “modifying diet,” such as smaller meals, low-fat and lactose-free diets, and “adequate hydration.”

Although acetazolamide is the most commonly used preventive medication, ^{25 -28} only a small fraction (5%) of the medical students identified acetazolamide as such, and only 2 respondents reported using it properly. A previous study reported that only 9% of tourists knew about acetazolamide as a preventive measure. ²² These studies highlight the lack of knowledge of this medication. In contrast, a study of experienced high altitude marathon runners participating in the Everest marathon found that 88% knew that symptoms could be prevented with medication, and 73% were aware of acetazolamide. ¹⁸

Limitations

Our small sample does not necessarily represent the general population of Latin America and did not reflect the relative populations of countries. We had a low response rate; as such, caution must be taken in generalizing these results to a broader sample. Also, students were not randomly selected for the study. The place of residence was determined according to the place where respondents studied, but this may not necessarily reflect their home residence. In our study, two-thirds of respondents were female. Although there has been an increase in female students attending medical schools in Latin America in recent years, this does not represent the current equal sex ratio of the general population. Our questionnaire contained multiple choice questions, limiting the ability of respondents to explain their answers. The respondents may not be representative of all Latin American medical students who potentially have even less knowledge of AMS.

Conclusions

Most medical students from South America attending a conference at 3400 m above sea level lacked basic knowledge of symptoms, treatment, and prevention of AMS. Forty-two percent of students met the criteria for AMS. It is important for physicians to know how to prevent, diagnose, and treat AMS. We recommend that Latin American medical schools incorporate high altitude medicine into their curricula.