Royal Navy Therapeutic Tables

Extract from INM Report 'Prevention and Management of Diving Disorders'

5.6. Table 60 - Hyperbaric Oxygen Therapy

5.6.1. Indications

This table, originally developed by Behnke in 1937 for the treatment of 'mild' decompression illness, has been used by the Royal Adelaide Hospital and the Royal Navy for the initial treatment of carbon monoxide poisoning. Table 66 should be used for repeat treatments. Table 60 may also be used as a Trial of Pressure in cases where the diagnosis of decompression illness is unclear. If the Trial of Pressure confirms a diagnosis of decompression illness the Table 60 should be converted to a Table 62 (paragraph 5.8). The advice of a diving medicine specialist must always be sought before commencing a Trial of Pressure.

5.6.2. Procedure

a.     The patient should start breathing oxygen on the surface. Those patients who have difficulty clearing their ears whilst wearing a mask may breathe chamber air until the treatment depth has been reached. Upon reaching the treatment depth the patient must immediately commence breathing oxygen.

 

b.     Descend to 18 msw over one to two minutes stopping if the patient or attendant has difficulty clearing his or her ears.

 

c.     The timing of the treatment begins on reaching 18 msw.

 

d.     The patient breathes 100% oxygen for two periods of 25 minutes, each followed by a 5 minute air break.

 

e.     Ascent rate from 18 msw to the surface should be at a continuous bleed rate of 3 msw every 5 minutes, except in cases in which descent to 18 msw exceeded 10 minutes. In such cases a stop should be made at 9 msw during which both the attendant and patient should breathe oxygen. The duration of this stop is to be half the time in excess of 10 minutes taken for the descent. If the resulting time is a fraction of a minute it should be rounded up to the nearest
whole minute. Example: descent to 18 msw takes 15 minutes; duration of stop (15 - 10)/2 = 2.5 minutes, rounded up this gives a stop of 3 minutes duration.

 

f.     The attendant must breathe oxygen during ascent from 9 msw to the surface.

 

g.    Severe cases may require repeat treatments over a period of days as frequent as every 4 hours. RN Table 66 is suitable for this purpose.

Table 60 - Hyperbaric Oxygen Therapy

5.7. Table 61 - Short Oxygen Recompression Therapy

5.7.1. Indications

This may be used for the management of missed decompression and considered for the treatment of acute decompression illness with limb pain, cutaneous or lymphatic manifestations ONLY. In cases of decompression illness, the patient should be given a careful neurological examination so that involvement of the nervous system, in particular, can be excluded.

5.7.2. Procedure
a.     The patient starts breathing O2 on the surface.
b.     Descend to 18 msw over one or two minutes stopping only if the patient or attendant have difficulty in clearing their ears.
c.     The time of the treatment starts on reaching 18 msw.
d.     If the symptoms of decompression illness are completely relieved within 10 minutes, decompression may proceed in accordance with Table 61. Otherwise use Table 62. Practically, this will mean that only a minority of cases will complete Table 61.
e.     The attendant should breathe oxygen during the O2 period at 9 msw and during the ascent to the surface.

Table 61 - Short Oxygen Recompression Therapy

Gauge Depth
(msw) Stops/Ascent
(minutes) Elapsed time
(hours and mins) Rate of Ascent
(msw/minute) Surface - 02:15 -

18	20 (O2)	00:00 - 00:20	-
18	5 (Air)	00:20 - 00:25	-
18	20 (O2)	00:25 - 00:45	-
18 - 9	30 (O2)	00:45 - 01:15	3 m in 10 min
9	5 (Air)	01:15 - 01:20	-
9	20 (O2)	01:20 - 01:40	-
9	5 (Air)	01:40 - 01:45	-
9 - 0	30 (O2)	01:45 - 02:15	3 m in 10 min

5.8. Table 62 - Standard Oxygen Recompression Therapy

5.8.1. Indications

This table is used for the great majority of cases of decompression illness which do not meet the criteria of paragraph 5.7. above.

5.8.2. Procedure
a.     The patient starts breathing O2 on the surface.
b.     Descend to 18 msw over one or two minutes stopping only if the patient or attendant have difficulty in clearing their ears.
c.     The timing of the treatment starts on reaching 18 msw.
d.     Upon reaching 18 msw the patient must be re-assessed. This assessment should take no more than 2-3 minutes and in most cases will reveal the patient's condition to have stabilised or starting to improve. However, very occasionally patients who have presented with serious symptoms arising shortly after surfacing, especially after very deep dives, rapid uncontrolled ascents, and submarine escape may fail to improve or continue to deteriorate at 18 msw. In all such cases, other than those following submarine escape training ascents (paragraph 5.15.), the chamber should be compressed to 30 msw on air with the patient breathing 50/50 heliox. Decompression will then normally be completed using Table 67. Submarine escape trainees (and divers where 50/50 heliox is not available) who continue to deteriorate after initial compression to 18 msw on oxygen should be compressed to 50 msw on air breathing 32.5:67.5 O2:N2. Decompression will then normally be completed using Table 63. In ALL such cases it is essential to contact a DIVING MEDICAL SPECIALIST. In very rare cases, continued deterioration may require transfer to Table 64 or 65.
e.     If the symptoms have remained static or improved incompletely after three 20 minute periods on 100% O2 at 18 msw, Table 62 may be extended. One, two or three further O2 breathing periods, separated by a 5 minute air break may be added on the advice of a diving medicine specialist. If the symptoms or signs have not resolved after two extensions at 18 msw further advice from the diving medicine specialist should be sought. Depending upon the nature and severity of the symptoms or signs, transfer to Table 64 may be necessary.

5.8.3     Symptoms may recur during decompression to 9 msw. In such circumstance HALT THE ASCENT. Recompress slowly (1 msw/min), to no deeper than 18 msw or until resolution of symptoms or signs occurs. Oxygen should be breathed throughout. Consult a Diving Medicine Specialist.

5.8.4     Symptoms may recur at 9 msw. Again, consult a diving medicine specialist. Depending on the nature and severity of the symptoms, a return to 18 msw or extending the table at 9 msw may be necessary. Table 62 may be extended for one or two 1 hour O2 breathing periods at 9 msw, separated by 15 min air breaks.

5.8.5     For an unmodified Table 62 or a Table 62 with a single extension at 9 msw or 18 msw, the attendant must breathe O2 for the last 30 minutes at 9 msw and during the ascent from 9 msw to the surface (60 minutes in total). If Table 62 is extended more than once, then the attendant should breathe O2 for the whole of the final O2 period at 9 msw and the ascent to the surface (90 minutes in total). If the attendant has undergone a hyperbaric exposure in the preceding 24 hours, an additional 60 minute period breathing O2 at 9 msw (150 minutes in total) should be undertaken.

Table 62 - Standard Oxygen Recompression Therapy

Gauge Depth
(msw) Stops/Ascent
(minutes) Elapsed time
(hours and mins) Rate of Ascent
(msw/minute) Surface - 04:45 -

18	20 (O2)	00:00 - 00:20	-
18	5 (Air)	00:20 - 00:25	-
18	20 (O2)	00:25 - 00:45	-
18	5 (Air)	00:45 - 00-50	-
18	20 (O2)	00:50 - 01:10	-
18	5 (Air)	01:10 - 01:15	-
18 - 9	30 (O2)	01:15 - 01:45	3 m in 10 min
9	15 (Air)	01:45 - 02:00	-
9	60 (O2)	02:00 - 03:00	-
9	15 (Air)	03:00 - 03:15	-
9	60 (O2)	03:15 - 04:15	-
9 - 0	30 (O2)	04:15 - 04:45	3 m in 10 min

5.9. Table 63 - Deep Air - Oxygen Recompression Therapy

5.9.1. Indications

The philosophy behind Table 63 is to provide an oxygen table after a brief period spent at 50 msw during which any bubbles present in the circulation, particularly of the brain, are minimised in volume through the effects of Boyle's Law. There are, however, disadvantages to employing this approach. Not least is the difficulty of attending patients compressed to 50 msw on air, where inert gas narcosis may severely compromise the performance of the attendant and an examining physician. Furthermore, the consequence of the deep phase of the table is to deliver a substantial inert gas burden to both patient and attendant which may impose unattractive decompression options in the event of an incomplete recovery at 50 msw. In addition, recent research has shown that the residence time for bubbles of gas in the cerebral circulation is likely to be brief, due to the powerful vasodilatation reflex which they stimulate. Consequently, there may be little requirement to use pressure to encourage bubbles to pass into the venous circulation. Finally, this table was developed specifically for the treatment of arterial gas embolism. Given the difficulties in making such a diagnosis and the potential disadvantages associated with an initial compression to 50 msw use of this table is reserved for those patients who present with rapid onset of severe symptoms following dives with minimal inert gas uptake and who show no significant improvement, or are continuing to deteriorate, when assessed following compression to 18 msw breathing oxygen (paragraph 5.8.2d). In practice this means that Table 63 will rarely be used except following submarine escape training ascents (paragraph 5.15) or when 50/50 heliox is unavailable .

5.9.2. Procedure
a.     Pressurise the chamber, without delay with air to 50 msw at the fastest rate that can be tolerated by the patient and attendant up to 30 msw per minute. If a gas mixture of 32.5:67.5 O2:N2 is available, this should be breathed by the patient via BIBS.
b.     If the patient is free of symptoms and signs after 25 minutes, and O2 is available, then decompression may be commenced using Table 63. If O2 is not available Table 64 should be used omitting the oxygen.
c.     If there are persisting symptoms and signs after 30 minutes at 50 msw, no matter how minor, Table 64 should be used.
d.     If the patient is deteriorating at 50 msw, contact a Diving Medicine Specialist as a matter of urgency. It may be necessary to compress the patient further and continue treatment using Table 65. This should not be contemplated however, unless:

(1)    A Diving Medicine Specialist is consulted
(2)    The chamber is capable of supporting a prolonged treatment

e.     Decompression from 50 msw to 18 msw should take 4 minutes after which Table 63 proceeds as for Table 62, except that the attendant must always breathe O2 during the final 60 minutes at 9 msw and subsequent ascent (90 minutes in total). If the attendant has had a previous hyperbaric exposure within 24 hours oxygen should be breathed for both 60 minute periods at 9 msw and during the ascent (total 150 minutes).

Table 63 - Deep Air - Oxygen Recompression Therapy

5.10. Table 64 - Deep Air - Oxygen Recompression Therapy

5.10.1. Indications

This table is used for cases which make an incomplete recovery while undergoing Treatment Tables 62, 63 or 67, or for the treatment of DCI in the absence of oxygen. It is applied as follows:

5.10.2. Procedure
a.     The table may be entered at any depth up to 50 msw from Treatment Tables 62, 63 or 67. Timing of the table should include any time previously spent at the depth of entry.
b.     When employed de novo (in the absence of oxygen) the rate of descent should be as fast as can be tolerated by the patient and attendant. This is normally of the order of 30 msw/minute. Timing of the table commences upon arrival at 50 msw.
c.     Ascent between stoppages is to take 5 minutes. This is not included in the stoppage times, but has been allowed for in the elapsed times.
d.     When used to treat a diver following a heliox dive, upon arrival at 50 msw 40:60 O2:He should be administered for periods of 20 minutes followed by 5 minutes breathing 20:80 O2:He. During the ascent from 50 to 18 msw the patient should breathe 20:80 O2:He. If 20:80 O2:He is not available then air may be used during the breaks from breathing therapeutic gas at depths between 50 - 18 msw. Upon arrival at 18 msw 100% oxygen should be administered with O2 breathing periods of 25 minutes duration followed by 5 minutes breathing chamber air. The patient, who must be closely monitored for evidence of pulmonary oxygen toxicity, should be given a minimum of four O2 breathing periods (for a total time of two hours) and thereafter to suit the patient's needs as advised by a Diving Medicine Specialist. The attendant should begin breathing 100% O2 two hours before leaving 9 msw, and both the patient and the attendant should breathe 100% O2 at 6 and 3 msw as shown in the table.
d.     Table 64 may be entered at 30 msw (paragraph 5.13) or 18 msw (paragraph 5.8.2.e), if advised by the Diving Medical Specialist who will also give instructions on oxygen breathing periods required. This guidance will take into account oxygen breathing before Table 64 was prescribed.
e.     Table 64 may be used breathing air if O2 is not available. In the absence of heliox, nitrox mixes of up to 40% O2 may be administered at 50 msw at the discretion of the Diving Medicine Specialist (the patient must be monitored closely for evidence of pulmonary oxygen toxicity).

5.10.3.

This is a long Table which should not be entered into without careful consideration. Prior to committing to a Table 64, the chamber supervisor must ensure that all life support considerations can be met.

Table 64 - Deep Air - Oxygen Recompression Therapy

Notes:
1. Oxygen breathing in accordance with paragraph 5.10.2.d.
2. The attendant should breathe O2 for 2 hours before leaving 9 msw.

5.11. Table 65 - Long Air Recompression Therapy

5.11.1. Indications

Table 65 is provided for use when the patient is severely ill and has not responded to treatment on Tables 62, 63, 64 or 67. IT IS ONLY TO BE USED HEN A DIVING MEDICINE SPECIALIST HAS BEEN CONSULTED and facilities exist for a prolonged treatment. Table 65 may also be used in the event of a failure of the oxygen supply during a Table 62, 63, 64 or 67. The Table may be entered at any depth down to 70 msw.

5.11.2. Procedure

a.     Rate of descent should be as fast as tolerable but no greater than 2 msw/minute.

b.     Rate of ascent is 1 msw/minute between stops.

c.     Stops are carried out at EVERY 1 MSW for the duration given in Column 3 of the table. The stop time begins when leaving the previous depth.

d.     If 32.5:67.5 oxy-nitrogen mixture is available this may be given at 50 msw. Pure O2 breathing may be introduced at 18 msw. O2 breathing periods should be of 25 minutes duration, alternating with 5 minute breaks breathing chamber air. Caution should be exercised in the repeated use of oxygen due to the risk of toxicity.

e.     Following heliox dives the patient should breathe 20:80 O2:He between 70 msw and 30 msw. 40:60 O2:He may be given at 50 msw with O2 breathing introduced at 18 msw. The attendant should breathe 20:80 O2:He, when available, between 70 and 30 msw.

Note: The attendant and patient need not breathe O2 during decompression which can be completed on air.

Table 65 - Long Air Recompression Therapy

5.12. Table 66 - Repeat Hyperbaric Oxygen Therapy

5.12.1. Indications

This table was developed specifically for the treatment of patients who require hyperbaric oxygen therapy. Table 66, by limiting the depth to 14 msw, reduces the probability of oxygen toxicity occurring amongst patients who may require a large number of therapies over the course of a number of weeks. Table 66 is NOT to be used as a primary treatment for acute decompression illness or carbon monoxide poisoning. This table may be used to re-treat cases of decompression illness and carbon monoxide poisoning in which there has been incomplete recovery or a recurrence of symptoms.

5.12.2. Procedure

a.     The patient should start breathing oxygen on the surface. Those patients who have difficulty clearing their ears whilst wearing a mask may breathe chamber air until the treatment depth has been reached. Upon reaching the treatment depth the patient must immediately commence breathing oxygen.

b.     Descend to 14 msw slowly allowing sufficient time for the patient to clear their ears. The descent will probably be achieved in between five to ten minutes but may take up to 30 minutes.

c.    The timing of the treatment commences on reaching 14 msw.

d.    The patient breathes 100% oxygen for three periods of 30 minutes with a 5 minute air break between the oxygen breathing periods.

e.    The ascent from 14 msw to the surface commences after 20 minutes of the third oxygen period has been completed and is at a continuous bleed rate of 1.4 msw per minute.

f.     The attendant must breathe oxygen for the last 20 minutes of the table including the 10 minute ascent from 14 msw to the surface.

g.    Serious cases may require several treatments per day. Where possible an interval of 4 hours should be left between treatments.

Table 66 - Repeat Hyperbaric Oxygen Therapy

5.13. Table 67 - Heliox/Oxygen Recompression Therapy

5.13.1. Indications

This table, a combination of the COMEX 30 table and Royal Navy Table 62, is to be used for the treatment of cases of decompression illness with serious symptoms or signs that do not improve, or which continue to deteriorate following an initial compression to 18 msw on 100% O2. It should also be used in all cases of omitted decompression, whether the diver is symptomatic or not, when the diver has completed less than 15 minutes of stops and the stops missed were at depths in excess of 18 msw. When contemplated for the treatment of decompression illness which fails to respond to treatment with standard oxygen recompression tables, the advice of a Diving Medicine Specialist should be sought.

5.13.2. Procedure

a.     The patient starts breathing 50:50 O2:He on the surface (or from 18 msw when transferring from Royal Navy Table 62, paragraph 5.82 (d)).
b.     Descend to 30 msw over three to four minutes stopping only if the patient or attendant have difficulty in clearing their ears.
c.     The timing of the treatment starts on reaching 30 msw.
d.     Upon reaching 30 msw the patient must be re-assessed. This assessment should take no more than 2-3 minutes and in most cases will reveal the patient's condition to have stabilised or starting to improve. However, very occasionally patients who have presented with serious symptoms arising shortly after surfacing may continue to deteriorate at 30 msw. In such cases the chamber should be compressed to 50 msw on air with the patient breathing heliox, 40:60 O2:He. Decompression will then normally be completed using Table 64. In ALL such cases it is essential to contact a DIVING MEDICAL SPECIALIST. In very rare cases, continued deterioration may require transfer to Table 65.
e.     If the patient is free of symptoms and signs after 55 minutes at 30 msw then decompression may be commenced using Table 67. If the symptoms have remained static or improved incompletely after 55 minutes at 30 msw, up to five additional 20 minute periods breathing 50:50 O2:He, separated by 5 minute breaks breathing 20:80 O2:He, may be added on the advice of a Diving Medicine Specialist. On completion of such extensions, decompression should be by Table 64 with 50:50 O2:He breathed during the ascent from 30 - 24 msw. A 5 minute break breathing 20:80% O2:He should be taken on arrival at 24 msw with 50:50 O2:He breathed during the remaining 25 minutes of the 24 metre stop and the ascent from 24 - 18 msw. Table 64 should then be completed in accordance with paragraph 4.10.
f.     If 20:80 O2:He is not available then air may be used during the breaks from breathing therapeutic gas at depths between 30 - 18 msw. Table 67 may, on the advice of a Diving Medical Specialist, be extended by one or two 20 minute O2 periods, separated by 5 minute air breaks, at 18 msw and/or one or two 60 minute O2 periods, separated by 15 minute air breaks, at 9 msw.
g.    For an unmodified Table 67 the attendant must breathe O2 during both 60 minute O2 periods at 9 msw and during the ascent from 9 msw to the surface (total 150 minutes). If the Table 67 is extended at 18 msw, by either one or two additional O2 periods, it must also be extended by an additional 60 minute O2 period at 9 msw during which time the attendant is to breathe O 2 (total 210 minutes). If the Table 67 is extended at 9 msw the attendant must breathe O2 for an additional 60 minute period (total 210 minutes). If the attendant has undergone a hyperbaric exposure in the preceding 24 hours Table 67 should be extended at 9 msw to permit the attendant to breathe O2 for an additional 60 minute period (total 210 minutes). In cases where Table 67 is extended at 30 msw, and decompression is by Table 64, the attendant should breathe oxygen as described in the instructions for Table 64.

Table 67 - Heliox/Oxygen Recompression Therapy

Note: If (20:80 O2:He) is not available air may be used

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