Note: This database is a quantitative summary of more detailed information contained in 119 case descriptions of DCS, available as Appendix IV.
Definition of Column Headings
1. Id: Subject identification number. Those with a dash “-“ extension show the number of times a JSC subject participated in a DCS test. Those with letters designate Duke (D), Hermann Hospital (H), or the Defense Research and Development Canada – Toronto (C) as the location of the DCS test. These ID numbers reflect the year of test (first two digits), the month of test (next two digits), and day of test (last two digits).
Final letter designates the exercise cot used by the subject, as many as four cots (A, B, C, and D).
2. Depend: Number to indicate “dependence” in these data related to subject ID that identifies multiple symptoms per subject. The same number repeated identifies the same subject with multiple symptoms.
3. Runnumb: A run number discriminator of a different test protocol when DEPEND is otherwise equivalent. For example, a DEPEND number of 21 appears six times. DCS symptoms were reported six times in subject 21 during three different protocols: two symptoms in the first protocol (RUNNUMB = 1), two in a second protocol
(RUNNUMB = 2), and two in a third protocol (RUNNUMB = 3). No subject had symptoms reported in four or more protocols. DEPEND and RUNNUMB are details needed to statistically evaluate dependency in the symptom data, else one must assume independence in the symptom data during statistical analysis.
4. Ht: Height in cm
13. Gender1: Gender per symptom. 1=male, 0=female
14. Bodyloc: Gross anatomical region where a symptom was located. 1=upper body, 0=lower body.
15. Ambul: Ambulation before and during altitude exposure. 1=yes, 0=no
16. Ambul1: Ambulation before and during altitude exposure per symptom. 1=yes, 0=no
17. Test: Test identification code indicating a unique test procedure.
18. ALTTIME: Time in hrs for the duration of the planned exposure.
19. P1: Specific altitude test pressure with psia unit, either 4.3, 6.5, 6.0, or 10.1.
20. TR360: Ratio of computed tissue N2 pressure in 360 half-time compartment to P1, or PB for any general ambient pressure, for resting prebreathe condition only. This calculation assumes 0 ml/kg/min O2 consumption, resulting in a 360 min half-time rate constant in denitrogenation equation that contains a term.
21. TRCOMBINED: Ratio of computed tissue N2 pressure in half-time compartment to P1 for resting prebreathe condition (3.5 ml/kg/min) when combined with half-time
compartments that varied due to exercise prebreathe in denitrogenation equation that contains a term.
22. Infile: Prebreathe data input file to Tissue Bubble Dynamics Model.
23. BGI360: Ratio of final computed bubble growth index to initial 3 micron micronuclei radius for the planned elapsed time at P1 – for scheduled end of test so BGI360 also applies to those without DCS. Mass balance and metabolic gas were included along with computed tissue N2 pressure in 360 min half-time compartment for resting prebreathe condition and when half-time compartment was variable due to exercise prebreathe.
24. Location: Reported anatomical location of a DCS symptom or in some cases a brief description of a symptom or DCS sign.
25. Symcount: Numerical sequence of reported symptoms.
26. Time1…10: Best assessment of elapsed time in minutes from the start of the test at altitude to the recollection or report of a DCS symptom.
27. BGI1…10: BGI360 associated with time of subsequent reported symptom. The appropriate BGI360 is after elapsed time from the start of test to report of symptom plus the time of ascent.
28. Scale1…10: A 0 to 10 symptom intensity scale provided by the test subject. When a range of intensity was reported, the mean intensity was used. When intensity was reported as < 1, then 0.9 was used. No entry associated with an elapsed time means that the subject did not report symptom intensity.
29. Maxinten: Maximum reported symptom intensity. When a range of intensity was reported, the mean intensity was used. When intensity was reported as < 1, then 0.9 was used.
30. Extp2: Extended time at P1. 1=yes, 0=no. Certain exposures, by design or accident, continued for an extended time after a symptom was reported. Information about the evolution of a symptom is only possible if Extp2 = 1.
31. Rlfp2: Symptom was completely resolved at the test altitude P1 before repressurization began. 1=yes, 0=no.
32. Rpstime: Elapsed time in minutes from start of test to start of repressurization from P1.
33. RpstimeBGI: BGI360 at the time of repressurization – reflects actual time for the subject with a symptom. RpstimeBGI may not equal bgi360 in all cases.
34. Symdeltm:Difference in time (minutes) at P1 between Rpstime – time1, being the time exposed to the symptom prior to repressurization.
35. Rlfp3: Symptom was completely resolved during the repressurization interval (about 5 to 15 minutes). 1=yes, 0=no.
36. Rlfpres3: Pressure in psia unit during repressurization from P1 where symptom resolved or the pressure of the test altitude if symptom resolved at P1 before start of repressurization. Test altitude was either 4.3, 6.5, 6.0, or 10.1 psia in one case.
37. Rlfpres3BGI: BGI360 at time where symptom resolved during repressurization.
38. Rlfp4: Symptom was completely resolved at site pressure. 1 = yes, 0 = other.
39. Rlfpres4BGI: BGI360 at time where symptom resolved at site pressure.
40. Rlfpres5BGI: BGI360 at time where symptom resolved during repressurization plus BGI360 at time where symptom resolved at site pressure (Rlfpres3BGI and
Rlfpres4BGI).
41. P2: Either Rlfpres3 or site pressure when symptom resolved at site pressure.
42. Deltap: Difference in pressure (mmHg unit, 1 psi = 57.1 mmHg) between Rlfpres3 - P1, and site pressure – P1 when Posttest = 1.
43. Volindex: Computed deltaP from Boyle’s Law: (P1 * 4/3(RPSTIMEBGI*3)3) / (4/3(RLFPRES5BGI*3)3) – P1, used to confirm that Boyle’s Law is the dominant factor to decrease BGI during the recompression step. Also can compute the “effective Boyle’s Law” change by following BGI reabsorption through time, either during GLO period or while breathing air. Computed volindex is close to observed deltap. 3.14159
44. Glo: Ground Level Oxygen (1 to 2 hrs) was continued as a treatment for symptoms that resolved at P1, during the repressurization from P1, or at site pressure, and if symptoms were still present at site pressure. 1=yes, 0=no.
45. Posttest: A symptom that resolved before subject was released but later reoccurred is designated with a 1 (9 subjects with 13 symptoms), a symptom that persisted after return to site pressure is designated as a 2 (9 subjects with 20 symptoms), and a 0 indicates no posttest symptom information.
46. Hbo: Hyperbaric Oxygen Treatment, either USN Treatment Table V or VI, that was required to resolve a persistent symptom at site pressure, a recurrent symptom, or even prophylactically when there was no symptom to treat. 1=yes, 0=no.
47. Rlfhbo: Symptom was relieved during HBO treatment. 1=yes, 0=no. An
indication of 0 means that HBO was provided but there was no symptom to resolve or the symptom did not resolve and was diagnosed as no DCS.
48. Dcstype: Symptom was designated as (1) for Type I pain-only or skin
manifestations or (0) for Type II serious. The presence of Cutis Marmorata (CM) by itself or in conjunction with other symptoms was designated as Type II since this was our historical convention. This convention no longer applies when CM appears in isolation from other symptoms. Type I includes joint pain, non-dermatomal pins and needles tingling, pruritus (skin itching), hot and cold sensations, urticaria, edema, muscle pain, and muscle spasm, while Type II includes fatigue, dizziness, blurred vision, CM, light headedness, abnormal reflex, cold sweat, cough, headache, dyspnea, hyperesthesia, substernal distress, numbness, nausea, paresthesia associated with dermatomal distribution, and impaired coordination. This list is not all-inclusive and is how symptoms were described in the combined NASA and USAF sources.
49. Loc: Same information as in column labeled “Location”.
50. Pain: Symptom attribute where “pain” described symptom.
51. Ache: Symptom described as an ache.
52. Sharp: Symptom described as a sharp or stabbing sensation.
53. Slight: Symptom described as a slight sensation.
54. Mild: Symptom described as a mild sensation.
55. Dull: Symptom described as a dull sensation.
56. Deep: Symptom described as deep in location.
57. Superfsl: Symptom described as superficial in location.
58. Discomf: Symptom described as a discomfort, a twinge, cramp, soreness, or even twitching.
59. Awareness: Symptom described as an awareness sensation.
60. Stiff: Symptom associated with stiffness, an inability to completely extend a limb.
61. Full: Symptom described as a fullness sensation.
62. Weakness: Affected location felt weak or fatigued, like weakness in a limb.
63. Numb: Numbness or cool sensation, associated with poor circulation.
64. Other: Symptom other than those attributed to musculoskeletal pain-only, often classified as Type II DCS symptoms.
65. Const: Symptom that was constant in nature.
66. Throb: Symptom associated with a throbbing sensation.
67. Interm: Symptom that was intermittent or transient in nature.