operating room environment

1. The Operating Room Environment
2080-04-25
Presenter: Dr. Mahadev Bhatta
1st Year Resident
Department of Anaesthesiology, PoAHS
Moderator: Dr. Sanish Gurung
Assistant Professor
Department of Anaesthesiology, PoAHS

2. OBJECTIVES
 Definition
 Importance of knowing about operating room environment?
Different zones in operating room
 Medical gas system
 Environmental factors in operating room
 Electrical safety
 Surgical fires and thermal injury
 Culture of safety

3. Operation theatre
• Is a Facility within a hospital with varying degree of sterility
• Equipped with surgical and anesthetic equipment for safe conduct of
surgical procedures.
• Efforts are directed to maintain vital function, prevent infection and
promote healing with safety, comfort and economy

7. • Are designed and made by combo effort of “Civil-mechanical-
electrical-electronic-biomedical” engineering
• Anaesthesia controlled time = 10-20%
• Surgeon and nurse controlled time = >80%

8. Why we need to understand operating room
environment?
• Time spent by anesthesiologist is more than any other medical specialty.
• Protection of patients and operating room personnel from a
multitude of dangers during surgery.
• Ensuring proper functioning of operating room’s medical gases,
environmental factors, fire prevention and management, and electrical
safety.

9. Types of Operation theatre
• Based on sterility
• ultra sterile (CTVS, Transplant)
• sterile
• septic
• Based on construction
• Modular
• Nonmodular
• Based on timing
• Routine
• Emergency

10. Modular vs non-modular ot
MODULAR NON MODULAR
Uses a mixture of Fresh air and Recycled air Uses 100% Fresh air
Laminar Air flow system Flow of air involves eddy currents
Anti-static flooring is an absolute requirement May not have anti-static flooring
Energy efficient up to 60% by using Recycled air Not energy efficient
Constructed by a single team of professionals who understands
the mechanics of Operation theatre
Constructed by multiple vendors at the time of hospital
construction, hence control becomes quite difficult
Contains standardized instrument and Equipment. Quality
control is easy
Quality control is quite difficult when multiple vendors are
used.
Mobility and handling of machine is easy Relatively hard
Each Modular OT has a different Air conditioning system thus
temp and humidity control is better
Uses a central air conditioning system .

11. Modular Nonmodular

12. Modular Nonmodular

13. Different zones of OT complex
• 4 zones base on
• Cleanliness
• Bacteriological count
• Positive pressure ventillation
• Protective zone/outer zone/dirty zone
• Clean zone
• Sterile zone
• Disposal zone

14. • OUTER ZONE/PROTECTIVE ZONE/DIRTY ZONE:
• Main access corrider, reception and waiting area for visitor
• Entrance to changing facilities.
• Accessible area for removal of waste
• Dirty utility room or soiledwork room( Sluice)
• CLEAN ZONE:
• Sterile supplies store (for sterile and clean supplies)
• General purpose store (equipments, X-rays, warming device, stretchers etc)
• Medication station, Anaesthesia room, Recovery room,
• STERILE ZONE:
• The restricted area of the operating suit includes operating and procedure room
including scrub room
• In this area surgical attire, hair coverings and masks are required in this area.
• Disposal zone:
• Dirty utility, waste disposal, disposal corrider

16. Protective/Dirty Zone

18. Clean Zone

21. Sterile Zone

22. Medical gas system
• We must be familiar with sources of the gases and the means of their
delivery to the operating room.
• Helps to prevent/detect medical gas depletion or supply line
misconnection.

23. • The medical gases commonly used in operating rooms :
• Oxygen
• Nitrous oxide
• Air
• Carbon dioxide
• Nitrogen.
• Vacuum exhaust

24. Oxygen
• Manufacturing: Fractional distillation of liquefied air.
• Storage: Compressed gas at room temperature or refrigerated as
a liquid.

25. Oxygen storage in small hospital
• Stored in two separate banks of H-cylinders connected by a manifold.

26. Storage of oxygen in large hospital
• Stored as liquid oxygen
• Stored below its critical temp:
–119°C

27. Emergency cylinder (E-cylinder)
• Pressure of 1000 psig in E-cylinder > approximately half full i.e
330 L of oxygen at atmospheric pressure and a temperature of
20°C.

28. Safety feature of E-cylinders
• Plug is made up of woods metal > low melting point.
• Dissipation of pressure in a fire that might otherwise heat the cylinder
to the point of explosion.
• Pressure relief valves ruptures at 3300 psig, well below the capacity of
E cylinders (more than 5500 psig pressure), preventing overfilling.

29. Nitrous oxide: N2O
• Used as an inducing agent for general anesthesia.
• Stored by hospitals in large H-cylinders connected by a manifold.
• Critical temperature:36.5°C
• To calculating residual volume of N2O in cylinder: Weigh them.

30. • Liquid N2O is kept at a constant temperature (20°C) & will vaporize at
the same rate at which it is consumed> will maintain a constant
pressure (745 psig) until the liquid is exhausted.
• The pressure gauge of a nitrous oxide cylinder should not exceed 745
psig at 20°C.
• Higher reading = gauge malfunction, tank overfill or a cylinder
contains gas other than nitrous oxide.

31. Medical air
• Obtained by blending oxygen and nitrogen.
• The critical temperature: –140.6°C.
• Dehumidified (but unsterile) air is provided to the hospital pipeline
system by compression pumps.
• The inlets of these pumps must be distant from vacuum exhaust vents
and machinery to minimize contamination.

32. Nitrogen
• Used to drive operating room equipment, such as saws, drills, and
surgical handpieces.
• Supply systems :H-cylinders connected by a manifold or a wall system
supplied by a compressor-driven central supply.

33. Vacuum
• Used for waste anesthetic gas disposal (WAGD) , surgical suction and
suction of secretions.
• Medical vacuum receptacles are black in color with white lettering.
• WAGD receptacles and tubing are lavender in color.

34. Carbon dioxide
• Odorless, colorless, nonflammable and slightly acidic gas.
• Used for insufflation of body cavities in laparoscopic or robotic-
assisted techniques .
• Stored in large cylinders: M-cylinders or LK cylinders

35. Prevention of cross-over of gases
• Pin index safety system
• Color coding of cylinders

36. Pin index safety system
• Safety system to prevent attachment of wrong cylinder into the anaesthesia
machine
* Consist of 2 holes on cylinder & their corresponding PINS ON YOKE ASSEMBLY
OF MACHINE (except Entonox which have only one pin at 7 position)
* PINS are a part of machine not cylinder
* PINS are 4mm in diameter & 6 mm long
* pin index fails if-
1) pins are damaged
2) wrong gas filled in cylinder

37. Fig: Pin index safety system

38. Gas Cylinder Pin Index
Oxygen 2,5
Air 1,5
Nitrogen 1,4
N2O 3,5
Entonox 7
CO2 2,6
Cyclopropane 3,6

39. Colour Coding of medical gas cylinder
• Cylinder colour coding is routinely used as the secondary
means of identification to ensure that the correct product is
chosen to administer to the patient.

40. Color coding of cylinders

43. Delivery of medical gases
• Delivered from their central supply source to the operating
room through a network of pipes .
• Pipes are sized such that the pressure drop across the whole
system never exceeds 5 psig.

44. • Hospital’s gas delivery system appears in the operating room as:
A. Gas columns
B. Ceiling hose drop
C. Articulating arms

45. Monitoring of medical gas
• Constantly monitored by central and area alarm systems.

46. Indicator lights and audible signals warn of:
1) Changeover to secondary gas sources
2) Abnormally high (eg, pressure regulator malfunction) or low (eg,
supply depletion) pipeline

47. Environmental factors in the operating room
• TEMPERATURE:
• Should be maintained For patient care
• Maintained between 68°F (20°C) and 75°F (24°C) in adults.
• Hypothermia : wound infection, impaired coagulation, greater
intraoperative blood loss, and prolonged hospitalization.

48. Humidity
• Maintained around 50%.
• Below this range the dry air facilitates airborne mobility of particulate
matter >vector for infection.
• High humidity > dampness can affect the integrity of barrier devices
such as sterile cloth drapes.

49. Ventilation
• A high rate of operating room airflow decreases contamination of
the surgical site.
• Blend of 80% recirculated air with fresh air.
• Separate waste anesthetic gas scavenging system must always
supplement operating room ventilation.
• Slight positive pressure to drive away gases that escapes
scavenging.

50. • The National Fire Protection Agency (NFPA) recommends 20 air
volume exchanges per hour to decrease risk of stagnation and
bacterial growth
• Air quality should be maintained by adequate air filtration using a
90% filter.
ACH= (CFM*60)/Volume of Room

51. HVAC system

53. Noise
• Measured at 70 to 80 decibels (dB) with frequent sound
peaks exceeding 80 dB.
• If the speaking voice has to be raised above conversational
level, then ambient noise is approximated at 80 dB.
• Exposure to noise has detrimental effect on human
cognition and may cause hearing impairment.

54. IONIZING RADIATION
• Sources: C-arm, fluoroscopy, linear accelerators, computed
tomography, directed beam therapy, proton therapy, and
diagnostic radiographs.
• Unit: Absorbed doses: gray, rad
Equivalent doses: sievert, roentgen equivalent in man
(REM)

55. • Radiation monitor is needed If a person is exposed to radiation more
than 40 REM.
• Basic principle of radiation safety: Keep exposure as low as
reasonably practical (ALARP)
• Radiation-sensitive organs(eyes, thyroid, and gonads) must be
protected via lead apron, thyroid collar and goggles.

56. Electrocution
• Body contact with two conductive materials at different voltage
potentials may complete a circuit and result in an electrical shock.
• Leakage current is present in all electrical equipment as a result of
capacitive coupling, induction between internal electrical
components, or defective insulation.

57. • The magnitude of such leaks is normally imperceptible to touch (<1
mA, and well below the fibrillation threshold of 100 mA).
• If the current bypasses the high resistance offered by skin.
and is applied directly to the heart, current as low as 100 μA
(microshock) may be fatal.
• The maximum leakage allowed in operating room equipment is 10
μA.

58. Electrocution safety

60. • If both the power lines are contacted or if either of power line
becomes grounded through a fault and the other line is contacted,
then it will complete the circuit causing shock.
• To reduce the chance of two coexisting faults, a line isolation monitor
measures the potential for current flow from the isolated power
supply to the ground.

61. • An alarm is activated if an unacceptably high current flow to the
ground becomes possible (usually 2mA or 5 mA).

62. Surgical Diathermy
(Electrocautery ,Electrosurgery)
• Electrosurgical units (ESUs) generate an ultrahigh-frequency electrical
current that passes from a small active electrode (the cautery tip)
through the patient and exits by way of a large plate electrode (the
dispersal pad, or return electrode).
• Ventricular fibrillation is prevented by the use of ultrahigh electrical
frequencies (0.1–3 MHz) compared with line power (50–60 Hz).

63. How surgical diathermy causes burn
• Malfunction of the dispersal pad:
A) Disconnection from the ESU
B) Inadequate patient contact
C) Insufficient conductive gel.
• In these situations, the current will find another place to exit (eg,
electrocardiogram pads or metal parts of the operating table), which
may result in a burn.

64. Precautions to avoid surgical diathermy burn
• Proper return electrode placement
• Avoiding prostheses and bony protuberances
• Elimination of patient-to-ground contacts.

65. • In a patient with implanted cardiac pacemaker or cardioverter
defibrillator, place the return electrode as close to the surgical field
and as far from the implanted cardiac device as practical as possible,
flow of current through it can malfunction it.
• Because pacemaker and electrocardiogram interference is possible,
pulse or heart sounds should be closely monitored when any ESU is
used.

66. Surgical Fires & Thermal Injury
• Incidence:1:87,000
• The most common risk factor for surgical fire relates to the open
delivery of oxygen.

67. Fire triangle/Fire triad

68. Fire triangle/Fire triad

69. Prevention and Management of Operating
Room Fires
Preparation:
Train personnel in operating room fire management
Practice responses to fires(fire drills)
Assure that fire management equipment is readily available
Determine if a high risk situation exists
Team decides how to prevent/manage fire
Each person assigned a task eg remove ET tube disconnect circuit

70. Prevention
• Allow flammable skin preparation to dry bfore draping
• Configure surgical drapes to avoid buildup of oxidizer
• Anaesthesiologist collaborates with team throughout the procedure
to minimize oxidizer-enriched environment near the ignition source
• Keep oxygen source as low as clinically possible
• Avoid N2O
• Notify surgeon if oxidizer and ignition source are in proximity to each
other
• Moisten gauze and sponges that are near an ignition source

71. Management
• General
• Look for early warning sign of a fire (eg pop, flash or smoke)
• Stop procedure and each team member immediately carries out assigned
task
• Airway fire
• Simultaneously remove the ET tube and stop gases/disconnect circuit
• Pour saline into airway
• Remove burning materials
• Mask ventilate patient, assess injury, consider bronchoscopy, reintubate

72. Fire on patient:
• Turn off gases
• Remove drapes and burning materials
• Extinguish flames with water, saline or fire extinguisher
• Assess patient’s status, access for smoke inhalation
Failure to extinguish situation:
• Use CO2 fire extinguisher
• Activate fire alarm
• Consider evacuation of room: close door and donot reopen
• Turn off medical gas supply to room

73. Culture of safety
• Identifies and stops unsafe acts before harm occurs.
• One tool that fosters the safety culture is the use of a surgical safety
checklist.
• Surgical safety checklist reduces incidence of preventable surgical and
anesthetic complications.

74. Surgical safety checklist

75. Monitoring in anaesthesia
• Blood Pressure
• ECG
• Pulse oximetry
• EtCO2
• Bi-spectral Index

76. Crew Resource management:
Creating a culture of safety in the operating
room
• Goal: To avoid errors caused by human actions.
• Developed in airline industry and gives any crew member the
authority to question situations that fall outside the range of normal
practice.
• Anyone with a concern must be able to speak up without fear of
repercussion.
• The benefit of this method in the operating room is clear, given
the potential for a deadly mistake to be made.

77. Principles of CRM
• (1) adaptability/flexibility
• (2) assertiveness
• (3) communication
• (4) decision making
• (5) leadership
• (6) analysis
• (7) situational awareness

78. Radio Frequency Identification (RFID)
• Radio frequency identification (RFID) technology utilizes a chip with a
small transmitter whose signal is read by a reader; each chip yields a
unique signal.
• Tracks the nursing, surgical, anesthesia personnel
• Tracks the patients
• RFID could be incorporated into surgical instruments and sponges,
allowing surgical counts to be performed by identification of the
objects as they are passed on and off the surgical field.

79. Take home messages
 Temperature: Between 68°F (20°C) and 75°F (24°C) for adults.
 Humidity: Between 20% and 60%.
 Keep radiation exposure as low as reasonably practical (ALARP)
 Use of lead apron, thyroid collar and goggles to protect against
radiation.

81. • If the current bypasses the skin and is applied directly to the heart,
current as low as 100 μA (microshock) may be fatal.
• Malfunction of the dispersal pad: Disconnection from the ESU,
inadequate patient contact, insufficient conductive gel.
• Proper return electrode placement, avoiding prostheses and bony
protuberances, elimination of patient-to-ground contacts to avoid
surgical diathermy burn.

82. • Fire triad: ignition ,oxidizer, fuel.
• Proper use of surgical checklist to assure safety culture.

83. Modular vs non-modular ot
MODULAR NON MODULAR
Uses a mixture of Fresh air and Recycled air Uses 100% Fresh air
Laminar Air flow system Flow of air involves eddy currents
Anti-static flooring is an absolute requirement May not have anti-static flooring
Energy efficient up to 60% by using Recycled air Not energy efficient
Constructed by a single team of professionals who understands
the mechanics of Operation theatre
Constructed by multiple vendors at the time of hospital
construction, hence control becomes quite difficult
Contains standardized instrument and Equipment. Quality
control is easy
Quality control is quite difficult when multiple vendors are
used.
Mobility and handling of machine is easy Relatively hard
Each Modular OT has a different Air conditioning system thus
temp and humidity control is better
Uses a central air conditioning system .

84. References:
• 1) Miller’s Anesthesia 9th edition
• 2) Morgan and Mikhail’s Clinical Anesthesiology 7th edition
• 3) Clinical Anesthesia –Paul G Baras 8th edition)
• 4) Understanding anesthesia equipment by Dorsch and Dorsch

85. Thank You!