Compliance:     HIOSH General Clause
                          Fed OSHAAct General Duty Clause 5
 

Introduction
Oxygen levels at the summit of Mauna Kea are approximately 60% that of sea-level. The body senses this deficiency of oxygen and makes adjustments to maintain a higher blood-oxygen saturation (SaO₂) level. Blood oxygen tests were conducted by L. Olsen at the W. M. Keck Observatory between December 13-15, 1994 as part of a project for the Hawai'i County Emergency Medical Services. Participants included observatory staff, non-observatory staff, and visitors at the summit. Saturation levels were monitored with an Involvo 4500 Scout SaO₂Monitor loaned by Hawai'i EMS, Waimea.

Upon initial ascent, non-observatory staff and visitors maintained an oxygen saturation level around 80% (1) during rest. This level dropped approximately 5-6% under exertion as minor as walking. Observatory staff, on the other hand, maintained blood oxygen levels of 90% at rest and faired much better under exertion, dropping only 3-4% under heavy exertion such as pushups and stair climbing.

It was noted that one visitor's oxygen level was well below 80% (~69%) and this individual appeared to have serious symptoms of early onset Acute Mountain Sickness (AMS). Another visitor's level was ~75%, and again this person was showing indication of AMS discomfort. Although only a small amount of data, it is suggested that below 80% saturation, onset of acute mountain sickness is likely.

Signs of AMS vary for different individuals. Most common is mild headache, blurred vision or gastrointestinal distress. To alleviate this discomfort, it is necessary to raise the blood-oxygen saturation. Pressure breathing or supplemental oxygen are two methods that work in raising blood oxygen. Test results however, indicated pressure breathing remedied symptoms more quickly than oxygen, moreover SaO₂ saturation levels remained higher longer with this technique.

Mountain/Pressure Breathing
Pressure Breathing is a mountaineering technique that forces more CO₂ and O₂ into the blood. It is extremely effective at the summit for relieving discomfort due to hypoxia. Use this technique for as long as necessary until symptoms disappear. Normally, it does not take long to increase the blood oxygen saturation, about 1 minute. If symptoms persist other problems may exist and descent is recommended. DO NOT HOLD YOUR BREATH, this will place additional stress on the lungs, possibly resulting in hemorrhaging.

• Take a large breath.
• Exhale half the volume slowly through pursed lips, under slight pressure.
• Exhale the remainder as normal.
• Repeat 6-7 times per minute. Do not repeat if dizziness persists after several minutes.

Administration
Syncope (fainting) is common among first time visitors to high altitude, ~5% (2). It is often a result of lowered left ventricle blood pressure and usually induced by moving too rapidly. Fainting most often occurs to first- time visitors and is fairly transient. Administer oxygen at a low flow rate of 3-6 lpm for only a few minutes. Response is usually rapid. Once the patient is conscious and coherent, discontinue supplemental oxygen and begin pressure breathing.

Serious AMS conditions, such as pulmonary or cerebral edema, require the administration of a constant flow of oxygen at a relatively moderate rate, 6-8 lpm. If the person responds well to oxygen application, flow rate may be lowered. Symptoms include rapid breathing, rapid heart rate, migraine- like headache, chest pain, delirium, etc. Descent to sea-level is essential.

If a victim is unconscious and not breathing, it will be necessary to use the bag resuscitator with the oxygen unit. Warning:mouth-to-mouth CPR is not effective in the rarefied atmosphere at the summit, an individual simply does not expel sufficient oxygen for the victim. The resuscitator unit stores oxygen, therefore the flow rate is not critical. Moreover, the resuscitator can be used without oxygen, hence CPR can begin before the oxygen line is connected. Once the victim is breathing on their own, switch to the free-flow mask.

Tip
Do not use oxygen as a cure all for minor discomfort. Let the body adjust. Pressure breathing is recommended for minor discomfort.

Instructions

• Open tank valve first, check gauge pressure. Do not let pressure drop below 200 psig or tank contamination may occur.
• Open flow rate valve to desired rate, e.g. 6 lpm.
• Place mask over nose and mouth of victim.
• Periodically check tank pressure, it must be over 200psi.
• NOTE: A victim may not be able to hold mask in place, use the head strap.

NOTE: If the resuscitator mask is being used, a tight fit is essential, therefore two people may be necessary to operate it effectively.

• Keep oxygen away from grease and oil, vegetable oils, flammable and combustible material: auto-ignition could occur.
• Keep mask clean!! Bloodborne Pathogens and Tuberculosis are very serious concerns.
• Periodically check regulator to monitor remaining oxygen.
• WARNING: It is possible to overdose on oxygen, be careful in its application. Overdose can result in total cardio- pulmonary shutdown. Never use oxygen for more than 2 hours unless directed by medical personnel.
• CAUTION: Some people panic with the mask on, do not leave a victim unattended!!