Physiological Responses at Rest and Exercise to High Altitude in Lowland Children and Adolescents.

Paulina Jopia,Guillem Vizcaíno-Muñoz,Ginés Viscor,Morin Lang,Juan Silva-Urra

doi:10.3390/life11101009

Paulina Jopia, Guillem Vizcaíno-Muñoz + Show 3 more

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https://doi.org/10.3390/life11101009

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Abstract

During the last decades, the number of lowland children exposed to high altitude (HA) has increased drastically. Several factors may influence the development of illness after acute HA exposure on children and adolescent populations, such as altitude reached, ascent velocity, time spent at altitude and, especially, their age. The main goal of this study was to evaluate the resting cardiorespiratory physiological and submaximal exercise responses under natural HA conditions by means of the six-minute walking test (six MWT). Secondly, we aimed to identify the signs and symptoms associated with acute mountain sickness (AMS) onset after acute HA exposure in children and adolescents. Forty-two children and adolescents, 18 boys and 24 girls aged from 11 to 15 years old, participated in this study, which was performed at sea level (SL) and during the first 42 h at HA (3330 m). The Lake Louise score (LLS) was recorded in order to evaluate the evolution of AMS symptoms. Submaximal exercise tests (six MWT) were performed at SL and HA. Physiological parameters such as heart rate, systolic and diastolic blood pressure, respiratory rate and arterialized oxygen saturation were measured at rest and after ending exercise testing at the two altitudes. After acute HA exposure, the participants showed lower arterial oxygen saturation levels at rest and after the submaximal test compared to SL (p < 0.001). Resting heart rate, respiratory rate and diastolic blood pressure presented higher values at HA (p < 0.01). Moreover, heart rate, diastolic blood pressure and dyspnea values increased before, during and after exercise at HA (p < 0.01). Moreover, submaximal exercise performance decreased at HA (p < 0.001). The AMS incidence at HA ranged from 9.5% to 19%, with mild to moderate symptoms. In conclusion, acute HA exposure in children and adolescent individuals produces an increase in basal cardiorespiratory parameters and a decrement in arterial oxygen saturation. Moreover, cardiorespiratory parameters increase during submaximal exercise at HA. Mild to moderate symptoms of AMS at 3330 m and adequate cardiovascular responses to submaximal exercise do not contraindicate the ascension of children and adolescents to that altitude, at least for a limited period of time.

Highlights

During the last decades the number of lowland children exposed to high altitude (HA)has increased drastically [1]
Regarding the comparison between genders of the responses in physiological parameters during the four different states of the 6 MWT performance, we only found statistical dissimilarities on dyspnea values at the end of exercise at HA between boys and gdirslssim(pi=la0ri.0ti3e8s).on dyspnea values at the end of exercise at HA between boys and girls (p = 0H.0o3w8)e.ver, when comparing the three BMI groups, as we can appreciate in Figure 7, we foHuonwdeavsetra, twishtiecnalcdoimffperaerninceg btheetwthereeneBBMMIIcgartoeugporsi,eassiwn ethceantoataplpdreisctiaanteceinwFailgkuerde a7t, wHeAf.oNunOd wa satlakteisdtic6a7l0d.2i7ffe±re3n1c.e78bemtw, eOenWBMinIdcivatideguoarlisesroinamtheedto6t4a5l .d4i5sta±n3c0e.0w4almkedanadt HOAB. cNhOildwreanlkereda6c7h0e.d27a±d3is1t.a7n8cme,eOveWn ilnodwiveridoufal6s1r1o.2a5m±ed3674.55.m45 (±p 3=0.00.405m). aIndaOddBitcihoinld, rwene orebascehrevdeda ldoiwstaenr cDeBePvevnallouweserinofN6O11p.2a5rt±ici3p7a.5ntms w(ph=en0.0c5o)m
Our results are consistent with the findings of Screase and colleagues (2009), who measured cardiorespiratory responses and daytime and overnight pulse oximetry in healthy lowland children, reporting mean SpO2 values of 88.9% at 3500 m (Namche, Nepal), which are similar to the values we report here [33]

Summary

Introduction

During the last decades the number of lowland children exposed to high altitude (HA)has increased drastically [1]. There is enough evidence to affirm that children are even more susceptible than adults to a wide range of altitude associated illness, such as acute mountains sickness (AMS), high-altitude cerebral edema or high-altitude pulmonary edema [5]. Among these symptoms, the development of AMS stands out; this appears on children after a rapid ascent at altitudes over 2500 m, taking into consideration the onset of headache, fatigue, dizziness, sleeping difficulties, anorexia, nausea, vomiting and changes in mental status [5,6]. These symptoms usually appear between 4 and 8 h after exposure to HA, they can present beyond 96 h after arrival [7]

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