Flight Medicine, Support and Experiences during Mountain Wave Project 99 in St. Martin de los Andes, Argentina, November/December 1999

History of High Altitude Flying and its medical aspects in the past:

• Wave Flying in recent times became increasingly important, as equipment and knowledge base have improved during the last ten to fifteen years. Wave Flights in the European Alpes covering long distances now happen more often. In New Zealand and France during the last world championships the competitors had to prepare for wave flights to altitudes of up to 7000 m. 
• At altitudes of more than 6000 m, No. 1 are certainly deadly without oxygen, No 2. Decompression Sickness (DCS) with Types I and II (minor symptoms up to CNS and cardiovascular collapse) can readily occur. 
• Adequate oxygen equipment and hypobaric chamber-training should be mandatory for this type of rigorous and demanding glider flying. It is imperative for flight safety. In the USA altitude records of around 15000 m and recent speed records (Jim Payne) were all done with aid of the wave!

In the USA, Poland, and the former GDR, hypobaric chamber training along with hyperbaric chamber facilities were widely supported by the authorities, even demanded in some places prior to wave flying.
• In Germany no offical guidance was present with respect to oxygen use when flying above 3000 m with obvious detriment to flight safety for a long time. This was the case for many years and no action was taken to improve this situation, even though expert opinion and knowledge in this field was available.- One famous "Alpensegelflieger", Jochen von Kalkreuth, was killed at high altitude several years ago, apparently due to confusion about the high altitude limits, and consequently dying of hypoxia. 

- A common situation was that expensive oxygen equipment was seldom bought and used. 
• With intensive support by the German Armed Forces, namely by Rainer Wienzek from Bueckeburg and the Military Flying Club and the knowledge and training by the Institute of Aviation Medicine the situation in Germany has improved during the last ten years. It was focused on the following main subjects: 1. Oxygen deficiency at altitude 2. Decompression Sickness (DCS) 3. Oxygen systems. 
• Inexpensive newly developed Oxygen Demand Systems, like "EDS" from Mountain High/USA and "Flowtimer" from Spiegelberg in Hamburg have helped to resolve the problems of the limited amounts of oxygen that can be carried aboard a glider. Now it was possible to fly for more than 11 h with a 5 ltr bottle at 4000 to 5000 m. 
• At high altitude new "Pulse Oxymetry" devices can measure the oxygen-amount available in the pilots body, more commonly known as the oxygen saturation of hemoglobin, using a sensor clipped on a finger. This measurement shows the pilot that he's either in a "safe" range or is becoming hypoxic.

Mountain Wave Project:

Altitude Physiology, Preparation and Training:

There is always a difference between theory and practice. A flight surgeon team discussed and proposed a detailed plan to prepare for this expedition to the Argentinian Andes. In fact not all of the preparation could be completed in time before the expedition started.

• Flight medical exams prior to travel with emphasis on heart, lung and hematologic functions.

-- We focused on health problems that could be exascerbated at high altitudes. Those were adressed in advance to provide a margin of safety for the participants. 
• Review of the basic literature to understand altitude physiology concerning gas, pressure, and diffusion laws.

-- This is mandatory to understand high altitude dangers for the planned hypobaric chamber training.
• Calculate oxygen requirements for the planned flight durations at the different altitudes to be flown.

-- A rule at altitude e.g.: O₂ consumption is 1 ltr oxygen at 200 bar, per hour, per person.-
• Prepare life support equipment for each glider to meet oxygen needs, including possible emergency situations.

-- This has to be done long time in advance to design systems and organize the equipment. One unsolved problem exists for altitudes above 6000 m, as a "rule of thumb" there is not enough space in the glider cockpit to store enough oxygen for this altitude. 
• Lectures in altitude physiology: (+ Pressure changes in the body + oxygen deficiency at altitude + type of oxygen deficiencies + time reserve(TUC) + decompression sickness + thermophysiology and others.) and a practical hypobaric chamber ride, version No.1.

-- This was the first chance to experience with hypoxic symptoms at 7500 m during a routine chamber run. The pilots had to get used to the chamber routine, to gain basic experience and learn O₂-discipline, like P.R.I.C.E.-Check et cetera. 
• Hypobaric chamber ride, version No. 2. Introduction and training-practice into the O₂-equipment used in the glider, redundant additional systems and review inflight emergency procedures. To learn, plan and discuss different emergency options during flight was emphasized. 
• Documentation of all flights. Logger, paper, standardized questionnaire. 
• Pre- and post-flight briefings conducted by a flight surgeon. These exchanges of experiences helped establish safe flying-criteria. 
• Plan SAR, find local support, like a *hyperbaric chamber, *needed hospitals, *rescue systems, *phone numbers. 
• Oxygen equipment needed for refills and further technical supply and support available at the home airport. 

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Preliminary experiences, results and proposals:

1. All gliders carried EDS from Mountain High as a primary oxygen system. These systems had their own O₂-bottle, independent of a second system. Stemme had two EDS Systems attached to the one EDS valve on one 5 ltr bottle. It seems to work correctly, but it has to be routinely checked for proper operation. It consisted of two systems connected to one valve. All bottles used are German Standard with 200 bar pressure carrying a 3 or 5 ltr bottle.

-- EDS has worked excellently, but it was more likely to run low on battery power, without the pilot noticing and without warning, if not monitored closely! This is dangerous and a point of concern! This situation happened more than once, and the EDS failed to operate due to low power. If more than one pilot flies the aircraft, some additional cross checking to insure adequate battery power has to be established.
Alternate operation has to be discussed, like everyday battery change or another permanent current resource such as solar panels.

There should be some test capability to be able to monitor such an apparatus, especially when it ages and more malfunctions may occur. These systems have no regular "Quality Test Regimen", as other aircraft equipment. 

2. As a second system: 
1. Stemme S10 VT, 115 hp, had a certified Bendix diluter demand system. The standard system GAF-in F4F, Alpha-Jet etc. It met all technical requirements, was equipped with masks, which were attached with Velcro tape on German military textile caps.
2. 

-- This seems to be an exellent solution and fits perfectly tight. Long elongated hoses for convenience. The system is built into the panel (one for each crewmember), so it can be operated individually. A 5 ltr bottle was an additional O₂ resource as an option.
For higher or longer flights there was a battery of six individual 1 ltr bottles, which fit behind one seat with specially constructed attachments and pressure valves.
Some pilots stated that they put the mask on in case of use at high altitude above 6000 m sometimes over the "nose-hose" of the EDS. They consider this a "Backup-System", if the diluter demand system runs out of oxygen. 
3. ASH25 M, 54 hp, had two EDS Systems attached to the one EDS valve on two 3 ltr bottles connected together. A big 5 ltr bottle is positioned parallel to the front of the aft seat. It serves two Draeger diluter demand systems, similar to the Stemme System. 
4. Nimbus 4 M, 40 hp, single seat. EDS and a small independent diluter demand system. Two O₂-bottles, an independent 5 and 2 ltr. 

In general: O₂-resources for flights up to 6000 m were sufficient, and in the case of higher altitudes there were time limits for its use. Up to now we do not meet officially recognized standards for oxygen supplies that can provide up to 15 hours flying time at higher altitudes!
Draeger Company states: Calculate altitude 6 to 11 K ; 1 ltr (bottle pressuriced 200 bar) per hour, per person)! To carry more oxygen bottles is nearly impossible, as there is also an engine and fuel tanks which take up space.
-- There has to be some movement for innovations in oxygen storage in these gliders. In technical terms, a bottle should be light weight, and samll in size or have the fuselage adapted for O₂ tanks. - This is a concern also for regular sport gliders.
-- Oxygen equipment/material is of military origin and often old and outdated. Technical testing cannot be done easily: There is an important safety factor!!
-- As long as this equipment is the only one primarily used, trained personnel and test equipment have to be available at the site by any means to keep the life support systems in first rate condition.

3. DCS Prevention

1. "Preventive Decompression Sickness (DCS) Oxygen Breathing" cannot be done sufficiently in the moment, due to the lack of oxygen reserves in the glider. In case of preplaned rapid quick climbs to more than 6000 m (e.g. to 8500 m) altitude cannot be done without danger. We need already 100% oxygen before take off and right from the start during the climb. This is mandatory to prevent Type II DCS Illness of a neurological nature, like severe headache, stroke, hearing loss, or partial blindness.

On the ground we calculate 15 ltr 100% O₂ per min (1 breath 750 ml times 20 per minute), which results in about 600 ltr O₂ in 40 min, which amounts to a 3 ltr container. See also ANNEX 1: Recommendations for High Altitude Glider Flying (DCS), J.Knueppel, Nov.1999
2. Teammembers did e.g. three flights on three consecutive days up to: No 1= 8000 m, No 2=5500 m, No 3= 8500 m. The flights lasted between nine (9) to eleven (11) hours, highest altitude valued with about three hours time.

Even though the pilots flew several times at this altitude, in these specific cases on three consecutive days, they experienced no signs of DCS-symptoms at all. 

Preliminary Conclusion:

• - High altitude physiology studies and hypobaric chamber training in advance is mandatory.
• - Technical planning, calculation and emergency training has to be performed.
• - If the oxygen systems are handled correctly O₂ usage is done in a professional manner.
• - O₂ systems must work properly, they need technical assistance, but they are not state of the art systems except for the EDS.
• - EDS performs well, but battery function has to be watched closely.
• - DCS is still a threat, but performed O₂/time regimen of O₂ prebreathing seems to prevent it so far up to 8000 m.
• - Oxygen storage is not sufficent if long duration flights of more than 3 hours are performed at altitudes above 6000 m.
• - Technical support and manpower for servicing O₂ equipment in the gliders should be improved.
• - Awareness of altitude physiology rules is present. But they have always been repeated and discussed in briefings again and again, to take care of flight safety in High Altitude Glider Flying.

Literature:

1. Evolved Gas, Pain, the Power Law, and Probability of Hypobaric Decompression Sickness, John Conkin et al.: ASEM, Vol 69, No 4, April 1998. 
2. Paradigms for the Treatment of Hypobaric Decompression Sickness, Todd S. Dart et al.: ASEM, Vol 69, No 4, April 1998. 
3. Guidelines for Treatment of Decompression Illness, Richard M. Moon et al.: ASEM, Vol 68, No 3, March 1997. 
4. 1990 Hypobaric Decompression Sickness Workshop: Summary and Conclusions, Andrew Pilmanis: AL/CFTS, Brooks AFB, Tx 78235, NATO AGARD Panel , April 1991 Towards New????. 
5. Inflight Denitrogenisation and Altitude Decompression Sickness Risk, Andrew Pilmanis: AL/CFTS, Brooks AFB, Tx 78235, Febr. 1992. 
6. An Abrupt Zero-Preoxygenation Altitude Threshold for Decompression Sickness Symptoms, James T. Webb et al.: ASEM, Vol 69, No 4, April 1998. 

Annex 1:

General Altitude Physiology-RECOMMENDATIONS for High Altitude Flying in High Mountains (DCS), Juergen K. Knueppel, Nov. 1999

Foreword:

All scientific knowledge is still under consideration, as many poblems are still not completely understood and solved. Nevertheless several empirical limits and insights have to be followed to prevent possible desasterous health disturbances! It is possible to be killed through DCS! 

The rules are not too simple, but the principles are easy to understand, when the pilots read and study the gas-laws.
Scientifically there are great interpersonal differences and situational variations in different people. The rules have some variables. 

Summary: General Facts and Rules

1. The barrier for DCS Symptoms without prebreathing oxygen and with a climb of 5000 ft per minute is 21000 feet.

Up to this altitude you will experience DCS Symptoms (which are by the rule muscular, skeletal, and pulmonary, and minor and major neurological symptoms in only about 5%, most pilots won´t suffer any symptoms at all. 
2. In case of prebreathing 100% oxygen, depending also of the time performed at this altitude, the barrier goes up.

The longer 100% oxygen is administered, the higher you can go without DCS sickness, only with operational limits. 
3. We have to differentiate two (2) main DCS symptoms:

Type I DCS: Symptoms are primarily bends; pain in the joints; considered minor!
Type II DCS: Symptoms are of neurological nature, brain and nerve-malfunction, considered severe! 
4. Important are the variables, like elapsed time, altitude, intensity, quality of onset etc., which determine outcome!

- Sudden incapacitation in flight, like hearing-loss or striking headache with vision-problems needs immediate care and special treatment to survive!
- Bends at altitude slowly developing with minor intensity, disappearing at descent requires 100% oxygen! 
5. All DCS symptoms need to be surveyed, they can return during 24 h and might require hyperbaric pressure.

Hyperbaric pressure chambers exist, portable and static, with the Navy and with Diving Companies.
They can save life and limb, and provide in diving accidents routine therapy. 
6. First Aid is:

a. always 100% Oxygen
b. and hydration by drinking isotone solutions, (water with 1/3 apple-juice, 1/2 teaspoon saline).
c. and transport to a hyperbaric chamber (low level), dive to 2 and 3 ATA for 2 to 5 hours, hopefully resolving!!
7. A mimimum prebreaething time of 100% oxygen, best between 15-16 000 feet (not higher!) doesn´t prevent minor DCS symptoms but prevents in most cases heavy Type II DCS symptoms. - The longer 100% O₂ the more useful for the body! 
8. High altitude above 10 km requires in addition 2 h 100% O₂ , e.g. on ground prebreathing-time. One hour 100% O₂ on 4000 m seems to have a similar effect. - DCS develops in general after 1 (one) hour time after ascent!! If this happens, the pilot has to descent immediately! 
9. After DCS-symptoms have appeared, you have to descent and breath 100% oxygen, until 2 h after landing. This method also should be applied as a safety procedure, when symptoms disappear during descent. 
10. Going up fast, staying up long at high altitude (e.g. 4 hours over 25000 ft) without prebreathing are considered the most important facts for develloping DCS.

-- 75% of all U 2 Pilots who fly at cabin altitudes of 30 000 ft, experienced DCS at least once in their flying carrier, even with 100% oxygen breathing and with timely prebreathing in advance! 
11. For diagnosing the DCS mishaps it is essential to document all important data as described above with a questionnaire. Debriefing after flight and a second questionnaire the next day is important to do. 
12. Decompression sickness in glider flying is pretty new. Even though the professional aviation world knows to take care of DCS, it wasn't considered to be a problem in the glider world. For long high altitude glider flights we have only a few experiences (Bob Weien, USA 1994). Scientifically it is a new terrain. 
13. If glider pilots go high above 6000 m, it is important to go higher stepwise by ascending slowly preferably in hours, than only in a few minutes. Take No DCS Risk!! 
14. If there was a high altitude flight and/or minor resolved Type I DCS Symptoms, No Flight the Next Day!! 
15. If in doubt: Ask a Doctor/diving doctor or flight surgeon over the phone for consultation, (Airforce, Navy also) or over one of the 24 hours worldwide emergency numbers:

like DANsuisse 0041 1 38311 oder DAN Europe 0039 085 8930333!