The Everest Base Camp trek is designed in such a way as to allow full acclimatization to prevent anyone from getting AMS (Acute Mountain Sickness). When trekking in the high altitude, the general rule is to keep a slow pace allowing the body enough time to adjust to the height gained every day. The higher the altitude, the less is the oxygen in the air and our body needs to adjust to this accordingly. It is therefore essential that we allow you sufficient time for acclimatization. Since this trek gains a maximum height of 5545m at Kala Patthar, it is important that we keep our pace slow and steady at least for the initial walking days. And in order to avoid the likelihood of being affected by altitude sickness, we have planned our itinerary by keeping the initial days of walking moderately within limits and by providing plenty of time for proper acclimatization. Further we have two days of acclimatization at Namche and Dingbohe before proceeding ahead to the higher altitude. Still, if you are concerned about it in anyway please refer to “Altitude illness” by Dr. Jim Duff” (http://www.treksafe.com.au/medical/altitude_illness.htm) who has provided detailed information about altitude sickness and the ways to prevent them.
The journey from Kathmandu to Everest base camp involves a forty-five minute flight to Lukla airstrip (2840m), followed by a ten-day trek up to base camp (5400m). Figure 1 shows the altitude during this multi-day ascent, as well as the names of the various towns and villages where most trekkers normally stay overnight (altitude may differ slightly depending on the chosen route in some itineraries). The long plateaus at Namche (3440m) in the following table for example reflects the rest day that is included which will allows additional time for physiological acclimatization after unusually large altitude gains on the previous days. Figure 2 shows the average blood saturation level of trekkers over the course of the ascent to Everest base camp, while figure 3 shows the corresponding average resting heart rate.
Preventing altitude sickness when trekking in Nepal: