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Anesthetic explosion dangers in dental operating rooms
ANESTHETIC
EXPLOSION OPERATING
DAlW?tRS ROOMS
IN DENTAL
M
ANY of the explosion dangers peculiar to the hospital operating room can be equally hazardous in t,he dental office in which inflammable anesthetic agents are used. As a matter of fact, the common neglect of such considerations in dental operating rooms would seem to accentuate the danger. Cyclopropane is the most dangerous of the explosive anesthetic agents but it is rarely, if ever, used in dental offices. The illcreasing popularity 01’ divinyl ether (Vinethene), the use of diethyl ether and ethylene, warrant attention to factors preventing explosion haznrtls in the dental operating room. The safety of Vinethene as a dental anesthetic depends upon the conditions prevailing in the particular case. A representative of Merck Iy: Company, Inc., manufacturers of Vinethene, emphasizes that is it is essential that appropriate safeguards he taken to prevent the accumulation of static eleetricity. “I ’ It is important to realize that the mixture of inflammable gas and oxygen must reach a specific ratio in order to cause an explosion (refer to Table I). This is a rare occurrence in open air, but the mout,h is an ideal location foi this mixture to be formed. If a dental burr is revolving on bone or I 00th structure during the administration of Vinethene, ether, or ethylene and oxygen anesthesia, in combination with a moving engine cord, there is aIW>Iys t,he possibility of an explosion. TABLE
ANESTHETIC AGENTS
/
I.
OF AIR TAEEN AS1
Ethvlene
0.97 1.45 2.23 2.42 2.56 1.52
Cyelopropane
Ethyl chloride Ether-&vinyl Ether-diethyl Nitrous oxide *(After tTests
Thomas, made in
LIMITS
8
George liter,
OF
E’LAM&IABILIW
OF AMWBIETICS”
I IN 1
I
J.: J. cylinderical,
LOW
IN
AIR 1
UP
1
LOW
OIGYGEK
/ IN rp
3.05 I 28.6 I 2.90 I 79.9 2.40 j 10.3 2.48 i 60.0 4.00 1 14.8 1 4.05 I 67.2 1.70t / 27.0t i 1.85 i 85.5 1.85t 1 36.5t ! 2.10 82.0 Not flammable _--~-I_-.--1 Not flammable Am.
Assoc. closed
Nurse steel
Anesthetists bomb.
18:26-29,
j
NITROUS LOW
OXIDF
I
IV ___.~..-~~-.. 1.90 1 40.2 1.60 j 30.:; 2.10 1 32.8 1.40 j 24.8 / 1.50 / 24.2 _-.I Not flammable - . .~
I j /
1950.)
General Considerations Tragedies from fires and explosions have occurred in operating rooms as long as inflammable anesthetic agents have been used. Though such accidents happen only once in approximately 100,000 anesthesias, the situation is usually a catastrophic one when it does occur.
990
BRUCE
L.
DOUGLAS
As long as inflammable or explosive gases or combinations of such gases are used it is advisable for both the surgeon and the anesthetist t,o take every precaution to avoid or at least minimize any danger from sparks, flames, 01 explosions. Static electricity is one of the main causes for explosions of anesthetic agents. It is, in essence, electricity at rest and is generated from friction between dissimilar or nonconductive materials. It is virtually impossible to prevent electrostatic changes due t,o continuous activity, but the accumulation of these changes can be prevented by providing paths for release as fast as they are generated. This can be accomplished by an efficient conductive floor and proper grounding of all movable objects, either with specially designed chains or wet towels. Experiments show that floors made from magnesium oxychloride and finely divided metallic copper have low electrical resistance and are more desirable than rubber, linoleum, porcelain tile, or marble. Conductive or leather-soled shoes should be worn by all personnel in the room to allow a free flow of static charges into t,he ground.2 Open flames, such as those provided by alcohol lamps, Runsen burners, and matches, should be prohibited in rooms where anesthetics are used or stored. High frequency cauteries or coagulators should not be allowed within a distance of two feet from the mouth of a patient receiving inflammable anesthetics3 On rare occasions, explosions of ether have resulted from the effects of sunlight,. Ether should be stored in dark glass bottles or the original can and should be removed from the anest.hetic machine at the end of each day. Electrical equipment should be inspected frequently to detect faulty operation. Roentgen-ray and fluoroscopic equipment can cause fire or explosion when inflammable anesthetic agents are being used.
Factors Causing Explosion There are four essential factors required for the development of an explosion :2 1. There must be combustible gases or vapors ; these gases or vapors consist of cyclopropane, ethylene, diethyl ether, divinyl ether, or a combination of these with each other or another substance. 2. There must be oxygen since it is essential to all ordinary combustion. 3. The ratio of gas and oxygen must be within certain limits, as shown in Table I; flames instead of explosions may occur when the ratios are outside of these limits. 4. There must be an ignition source, which can consist of small flames, incandescent surfaces, local combustion initiated by catalysts and electric Among t,he electrostatic hazards are the engine belt on a dental sparks. motor, or the rotating burr, or the engine itself. Electrocautery or electrosurgical equipment offers obvious dangers. The humidity of a room can effect the accumulation of static electricity. Most authorities agree that air-conditioned rooms are desirable in warm, sultry weather.2
Floors for Anesthetizing
Areas
alas. the special function whic:l! In considering floors for anesthetizing should be most stressed is that the floor must he nblr to carry away ‘OI’ dissi pate “static. ” Thomas4 stresses the intport,ancc>. therefore. of conductive flooring of magnesium osychloride and finely diyitletl Inrtalli(~ copper. Dr. George Thomas, Professor of Anesthrsi~~logy at the I’niversity of Pittsburgh Medical School, in conjunction bvith the rnited States lhre;l~~ the problem of ant+ of Mines, has spent a great deal of time inv&igating t,hetic explosions and is admittedly the foremost, espert ou the subject. IIt1 has devised the following table of rules for avoiding firtss and explosions ’ I. Avoid wool, silk, nylon, sharkskin. Ilonc~orrdllc.ti~-(~ rubber, plactic% et<*., in anest,het,izing locations. 2. Keep visitors away from the allestllrtist nncl his equipment when IISing inflammable anesthetic agents. 3. Use extreme caution in moving anesthtltic: ap)&ancaes. In this regarcl, a communication from the McKesson Xppliallce ( ‘om))an?. atlviscs t-hat Ijoth the patient and the equipment should be touched before releasing the gases, theribby assuring that the anesthetic unit and the patient, are at the same pot,ential. if any.” 4. Caution should be exercised in eonnecfing and disconnecting masks. breathing bags, or tubes because handling can protluce electrostatic chargcl. 5. Conductive soled shoes should be worn in the operating room. Ii these are unobtainable, leather soles are less objectionable than ordinaq~ rubber or composition shoes, 6. Conductive floors should he installed in a11 anesthetizing locations. 7. All equipment on the floor should lnakta I)rol)er electrical conta.vt with the floor. 8. Paper wrappings should be I~enro~ed More ~)lacing Kits cylindt~rs in service SOthat the cylinder label can be clearly risible. 9. Do not permit oil, grease, or inflaIrunal)le liquids to come in c*onta(~l with oxygen cylinders, valves, regulators, gauges, OFfittings. 10. Do not lubricate regulators, fittings. OY aaup~ with oil or any ot)\rt* inflammable substance. 1.1. Alwa.ys clear the particles of dust and dirt from the outlet, ol’ t’iI(*ll cylinder by slightly opening and closing the valve before applying any fitti!1: to the cylinder. 12. Do not permit oxygen to enter the regulator suddenly. Open iht, valve slowly. When opening the valve, point the face of the regulator yat~g(b away from the operator and other personnel. 13. Do not use oxygen fittings, valves, regulators, or gauges for any s(‘I*Yice except oxygen. 1% Gases should never be mixed in, or added to, an oxygen cylin~lrr or any other cylinder. 15. Do not attempt to use regulators that a,re in need of repair, or (ylinders having valves that do not operate properly.
992
BRUCE L. DOUGLAS
16. Do not attempt to repair defective oxygen equipment unless properly trained and qualified for such work. 17. Cylinder valves should be fully opened when in use. 18. Cylinder valves should be closed at all times except when gas is actually being used. Always be on the alert against that silent, unseen hazard that is least A spark understood and most neglected, “static or frictional electricity.” that can scarcely be seen or felt can prove disastrous. Buckles? adds as a final precaution to eliminate the practice of “washing out the patient” and the apparatus with oxygen following the anesthesia. References 1. Kraus, 2. 3. 4. 5. 6.
F. (Representative of Merck & Company, Inc.) : Personal communication, Nov. 8, 1950. Hazards in Operating and Delivery Rooms, J. Am. Assoc. Thomas, George J.: Explosion Nurse Anesthetists 18: 26-29, 1950. Personal communication from Course on the Basic Sciences as Thomas, George J.: Related to Anesthesiology. University of Pittsburgh Medical School, June, 1950. 15: 7, 1951. Thomas, George J.: News Letter of the Am. Sot. Anesthesiologists Bloomheart, J. L. (Vice-President of McKesson Appliance Company, Toledo, Ohio): Personal communication, Jan. 19, 1951. Explosions, J. Thoracic Surg. 21: 426, 1951. Buckles, M. G.: Anesthetic
720 C~RNWELLAvs.
EXPLOSION OPERATING
DAlW?tRS ROOMS
IN DENTAL
M
ANY of the explosion dangers peculiar to the hospital operating room can be equally hazardous in t,he dental office in which inflammable anesthetic agents are used. As a matter of fact, the common neglect of such considerations in dental operating rooms would seem to accentuate the danger. Cyclopropane is the most dangerous of the explosive anesthetic agents but it is rarely, if ever, used in dental offices. The illcreasing popularity 01’ divinyl ether (Vinethene), the use of diethyl ether and ethylene, warrant attention to factors preventing explosion haznrtls in the dental operating room. The safety of Vinethene as a dental anesthetic depends upon the conditions prevailing in the particular case. A representative of Merck Iy: Company, Inc., manufacturers of Vinethene, emphasizes that is it is essential that appropriate safeguards he taken to prevent the accumulation of static eleetricity. “I ’ It is important to realize that the mixture of inflammable gas and oxygen must reach a specific ratio in order to cause an explosion (refer to Table I). This is a rare occurrence in open air, but the mout,h is an ideal location foi this mixture to be formed. If a dental burr is revolving on bone or I 00th structure during the administration of Vinethene, ether, or ethylene and oxygen anesthesia, in combination with a moving engine cord, there is aIW>Iys t,he possibility of an explosion. TABLE
ANESTHETIC AGENTS
/
I.
OF AIR TAEEN AS1
Ethvlene
0.97 1.45 2.23 2.42 2.56 1.52
Cyelopropane
Ethyl chloride Ether-&vinyl Ether-diethyl Nitrous oxide *(After tTests
Thomas, made in
LIMITS
8
George liter,
OF
E’LAM&IABILIW
OF AMWBIETICS”
I IN 1
I
J.: J. cylinderical,
LOW
IN
AIR 1
UP
1
LOW
OIGYGEK
/ IN rp
3.05 I 28.6 I 2.90 I 79.9 2.40 j 10.3 2.48 i 60.0 4.00 1 14.8 1 4.05 I 67.2 1.70t / 27.0t i 1.85 i 85.5 1.85t 1 36.5t ! 2.10 82.0 Not flammable _--~-I_-.--1 Not flammable Am.
Assoc. closed
Nurse steel
Anesthetists bomb.
18:26-29,
j
NITROUS LOW
OXIDF
I
IV ___.~..-~~-.. 1.90 1 40.2 1.60 j 30.:; 2.10 1 32.8 1.40 j 24.8 / 1.50 / 24.2 _-.I Not flammable - . .~
I j /
1950.)
General Considerations Tragedies from fires and explosions have occurred in operating rooms as long as inflammable anesthetic agents have been used. Though such accidents happen only once in approximately 100,000 anesthesias, the situation is usually a catastrophic one when it does occur.
990
BRUCE
L.
DOUGLAS
As long as inflammable or explosive gases or combinations of such gases are used it is advisable for both the surgeon and the anesthetist t,o take every precaution to avoid or at least minimize any danger from sparks, flames, 01 explosions. Static electricity is one of the main causes for explosions of anesthetic agents. It is, in essence, electricity at rest and is generated from friction between dissimilar or nonconductive materials. It is virtually impossible to prevent electrostatic changes due t,o continuous activity, but the accumulation of these changes can be prevented by providing paths for release as fast as they are generated. This can be accomplished by an efficient conductive floor and proper grounding of all movable objects, either with specially designed chains or wet towels. Experiments show that floors made from magnesium oxychloride and finely divided metallic copper have low electrical resistance and are more desirable than rubber, linoleum, porcelain tile, or marble. Conductive or leather-soled shoes should be worn by all personnel in the room to allow a free flow of static charges into t,he ground.2 Open flames, such as those provided by alcohol lamps, Runsen burners, and matches, should be prohibited in rooms where anesthetics are used or stored. High frequency cauteries or coagulators should not be allowed within a distance of two feet from the mouth of a patient receiving inflammable anesthetics3 On rare occasions, explosions of ether have resulted from the effects of sunlight,. Ether should be stored in dark glass bottles or the original can and should be removed from the anest.hetic machine at the end of each day. Electrical equipment should be inspected frequently to detect faulty operation. Roentgen-ray and fluoroscopic equipment can cause fire or explosion when inflammable anesthetic agents are being used.
Factors Causing Explosion There are four essential factors required for the development of an explosion :2 1. There must be combustible gases or vapors ; these gases or vapors consist of cyclopropane, ethylene, diethyl ether, divinyl ether, or a combination of these with each other or another substance. 2. There must be oxygen since it is essential to all ordinary combustion. 3. The ratio of gas and oxygen must be within certain limits, as shown in Table I; flames instead of explosions may occur when the ratios are outside of these limits. 4. There must be an ignition source, which can consist of small flames, incandescent surfaces, local combustion initiated by catalysts and electric Among t,he electrostatic hazards are the engine belt on a dental sparks. motor, or the rotating burr, or the engine itself. Electrocautery or electrosurgical equipment offers obvious dangers. The humidity of a room can effect the accumulation of static electricity. Most authorities agree that air-conditioned rooms are desirable in warm, sultry weather.2
Floors for Anesthetizing
Areas
alas. the special function whic:l! In considering floors for anesthetizing should be most stressed is that the floor must he nblr to carry away ‘OI’ dissi pate “static. ” Thomas4 stresses the intport,ancc>. therefore. of conductive flooring of magnesium osychloride and finely diyitletl Inrtalli(~ copper. Dr. George Thomas, Professor of Anesthrsi~~logy at the I’niversity of Pittsburgh Medical School, in conjunction bvith the rnited States lhre;l~~ the problem of ant+ of Mines, has spent a great deal of time inv&igating t,hetic explosions and is admittedly the foremost, espert ou the subject. IIt1 has devised the following table of rules for avoiding firtss and explosions ’ I. Avoid wool, silk, nylon, sharkskin. Ilonc~orrdllc.ti~-(~ rubber, plactic% et<*., in anest,het,izing locations. 2. Keep visitors away from the allestllrtist nncl his equipment when IISing inflammable anesthetic agents. 3. Use extreme caution in moving anesthtltic: ap)&ancaes. In this regarcl, a communication from the McKesson Xppliallce ( ‘om))an?. atlviscs t-hat Ijoth the patient and the equipment should be touched before releasing the gases, theribby assuring that the anesthetic unit and the patient, are at the same pot,ential. if any.” 4. Caution should be exercised in eonnecfing and disconnecting masks. breathing bags, or tubes because handling can protluce electrostatic chargcl. 5. Conductive soled shoes should be worn in the operating room. Ii these are unobtainable, leather soles are less objectionable than ordinaq~ rubber or composition shoes, 6. Conductive floors should he installed in a11 anesthetizing locations. 7. All equipment on the floor should lnakta I)rol)er electrical conta.vt with the floor. 8. Paper wrappings should be I~enro~ed More ~)lacing Kits cylindt~rs in service SOthat the cylinder label can be clearly risible. 9. Do not permit oil, grease, or inflaIrunal)le liquids to come in c*onta(~l with oxygen cylinders, valves, regulators, gauges, OFfittings. 10. Do not lubricate regulators, fittings. OY aaup~ with oil or any ot)\rt* inflammable substance. 1.1. Alwa.ys clear the particles of dust and dirt from the outlet, ol’ t’iI(*ll cylinder by slightly opening and closing the valve before applying any fitti!1: to the cylinder. 12. Do not permit oxygen to enter the regulator suddenly. Open iht, valve slowly. When opening the valve, point the face of the regulator yat~g(b away from the operator and other personnel. 13. Do not use oxygen fittings, valves, regulators, or gauges for any s(‘I*Yice except oxygen. 1% Gases should never be mixed in, or added to, an oxygen cylin~lrr or any other cylinder. 15. Do not attempt to use regulators that a,re in need of repair, or (ylinders having valves that do not operate properly.
992
BRUCE L. DOUGLAS
16. Do not attempt to repair defective oxygen equipment unless properly trained and qualified for such work. 17. Cylinder valves should be fully opened when in use. 18. Cylinder valves should be closed at all times except when gas is actually being used. Always be on the alert against that silent, unseen hazard that is least A spark understood and most neglected, “static or frictional electricity.” that can scarcely be seen or felt can prove disastrous. Buckles? adds as a final precaution to eliminate the practice of “washing out the patient” and the apparatus with oxygen following the anesthesia. References 1. Kraus, 2. 3. 4. 5. 6.
F. (Representative of Merck & Company, Inc.) : Personal communication, Nov. 8, 1950. Hazards in Operating and Delivery Rooms, J. Am. Assoc. Thomas, George J.: Explosion Nurse Anesthetists 18: 26-29, 1950. Personal communication from Course on the Basic Sciences as Thomas, George J.: Related to Anesthesiology. University of Pittsburgh Medical School, June, 1950. 15: 7, 1951. Thomas, George J.: News Letter of the Am. Sot. Anesthesiologists Bloomheart, J. L. (Vice-President of McKesson Appliance Company, Toledo, Ohio): Personal communication, Jan. 19, 1951. Explosions, J. Thoracic Surg. 21: 426, 1951. Buckles, M. G.: Anesthetic
720 C~RNWELLAvs.