Pain Management- Inhalation Sedation: Equipment

flowmeters- digital electronic flow

-control devices are now available on N2O-O2 sedation devices

delivery pressure

-45 to 55 psig

N2O cylinder and contents

-N2O is present in both liquid and gaseous states -because of the presence of liquid N2O in the cylinder, the gas pressure gauge will record "full" as long as any liquid remains in the cylinder -the pressure gauge for N2O therefore cannot be used as an accurate measurement of contents

O2 cylinder and contents

-O2 cylinder contains only gas -pressure gauge on machine yoke reflects actual contents of cylinder -although there are additional safety features to prevent administration of 100% N2O -the administrator can see the "fuel gauge" for O2 and can open a new cylinder before the nearly empty cylinder is depleted

nasal hood

-a device designed to fit comfortably and securely over the patient's nose -tubes deliver gases from sedation unit -2 tubes deliver gases, 2 tubes carry away exhaled gases

yokes- safety feature

-a diameter index safety system (DISS) -designed to ensure correct gas enters the correct part of the sedation machine -diameters of attachments are different and threading of attachments differs -makes it physically impossible to inadvertently attach wrong tubing to wrong inlet of machine

Nitronox

-a type of demand-flow used in hospital and ambulatory settings -unique in that percentage is not adjustable -is fixed at 50/50 O2 and N2O and is extremely accurate

ratio of use

-about 2.5 cylinders of O2 are used for every N2O cylinder

flowmeters- adjustment of gas flow

-adjustment of gas flow is accomplished by a fine-needle valve for each flowmeter, the knobs are both touch-coded and color coded -in US O2 control knob is green and fluted, N2O knob is flue and not fluted -O2 flowmeter is positioned on the right side of flowmeters

latex-free accessory equipment

-all equipment used on N2O-O2 administration is latex-free

safety features: color coding

-all parts of the sedation unit that carry or operate O2 are colored green -tubes, knobs, and other parts handling N2O are colored light blue

conducting tubes

-also called breathing tube -connects bag-tee to nasal hood -large diameter and corrugated, minimizes resistance to flow of gases and prevents kinking

regulators

-also called reducing valves -located between compressed-gas cylinder and flowmeter -in central storage systems, regulators are commonly placed on cylinder itself

flowmeters- gases

-anesthetic gases leave the tops of their respective flowmeters and are combined in the mixing chamber, found in the head of the sedation unit -a combination of gases flows through the machine and now exit the sedation unit through the outflow tube, known as a bag-tee and carried to the patient

yokes (portable system only)

-assembly holds cylinder of compressed gas tightly in contact with portable sedation unit -metal pins will accept only one specific type of compressed gas- pin index system

automatic manifold

-automatically activates a new full reserve cylinder of gas when cylinder in use empties

safety features: oxygen fail safe

-automatically terminates the flow of N2O whenever the delivery pressure of O2 falls below predetermined level (approx. 50 psig) -when the delivery pressure of O2 through the reducing valve can no longer be maintained at 50 psig, the O2 fail-safe mechanism is activated and the flow of N2O gas is terminated

portable system disadvantage

-because they require use of smaller cylinders, they require replacement more frequently and cause a higher cost

reservoir bag

-bladder-type bags, with the 3-L used most commonly in dentistry -attaches to base of bag-tee, usually immediately below emergency air inlet valve -a portion of the gases may be diverted into the reservoir bag

flowmeters calibration

-calibrated only for the gas that will flow through them -calibrations on the tube indicate flow of gas in L/min

reservoir bag third potential function

-can provide O2 during assisted ventilation -usually only practical with full-face mask

size of cylinders

-classified by a letter -"A" the smallest -"HH" the largest -"E" are both N2O and O2 -"G" are N2O and "H" for O2 use in central storage systems

handling compressed gas cylinders 6

-close all cylinder valves tightly when not in use to prevent contamination from water or dirt regardless if cylinder contains gas or is empty

safety features of cylinders

-color coded: N2O blue, O2 green -pin index safety system makes it physically impossible for a N2O cylinder to be inadvertently attached to O2 portion

continuous-flow units

-contain flowmeters, characterized by continuous flow of gases regardless of respiratory pattern of patient -gas continues to be delivered through the machine even as patient exhales -use greater volume of gas over a given period of time than the demand-flow unit

how the demand-flow unit works

-contains one dial which changes the percentages of gases delivered -dial provides a direct indication of the percentage of O2 delivered in the mixture; the remainder of the gas is N2O -units only show what was set, not what was actually delivered

types of inhalation sedation units

-continuous flow machine -intermittent or demand flow unit

handling compressed gas cylinders 7

-cylinders should be "cracked" before attached to sedation machine -meaning open just slightly allowing some gas to escape blowing out any particles of dust that may have lodged in the orifice of the cylinder

demand-flow unit

-does not deliver gas continuously to the patient -varies rate of flow of delivered gas according to patient's respiratory demands and requirements

demand-flow unit advantages

-economy obtained from the decreased volume of compressed gases used

demand-flow unit disadvantage 1

-flow of anesthetic gases per minute is not visible or registered anywhere on the machine -instead there is a dial on which percentage of gases are recorded and another on which the pressure at which they are delivered is visible

flowmeters

-from reducing valves, individual gases are carried through low-pressure tubing into back of sedation unit, gases then directed to flowmeters -permits administrator to deliver a precise volume of either gas to patient

yokes- reducing valves

-from reducing valves, the gas enters low-pressure tubing, color-coded for specific gases, that conducts gas to attachments at the rear of sedation unit

how flowmeters work

-gas enters a taper tube, grow wider from bottom to top -a float is inside the flowmeter for measuring volume -when flow of gas begins, the gas forces the float up into the tube

compressed gas cylinders

-gases dispensed at a pressure greater than 25lb per square/ 25psig-pounds per square inch gauge pressure at 25ºC or 70ºF are considered compressed gases according to hazardous materials regulations of the US DOT -because of potential for serious injury from improper handling of these cylinders, DOT has regulations

why keep grease and oil away from compressed gases

-grease or oil in the presence of a compressed gas forms a potentially explosive mixture -when a cylinder is opened, gas rushes from the cylinder into the restricted space of the reducing valve -the temperature may increase enough for a few seconds to ignite any combustible materials that may be present (grease or oil)

is the continuous-flow unit safe?

-greater accuracy and safety compared to demand-flow

handling compressed gas cylinders 4

-handle cylinders with care, especially avoid dropping them

safety features: alarm

-if there is a shutting off of gas flows on the unit, the alarm system is activated

N2O cylinder pressure

-in a full tank of N2O is 650-900psi -in a half-tank of N2O is 650-900psi -this is because the contents of a tank of N2O contains both liquid and gas

emergency air intake valve use

-in the event the sedation unit ceases to function and gas flow from the machine is terminated, it provides a supply of atmospheric air

safety features: minimum oxygen liter flow

-inhalation sedation units are designed so that once turned on the unit delivers a preset minimum liter flow of O2 through the flowmeter -in most units it's 2.5 or 3 L/min of O2 -the flow of N2O cannot start until a flow of O2 has been established

regulators temperature

-it is in the reducing valve that recompression of gases produces the tremendous increase in temperature to 815-1093ºC (1500-2000ºF) -this happens when a cylinder of O2 at 2200 psig is quickly opened and high pressure gas is forced into a reducing valve -although the reducing valve lowers pressure to about 50 psig, gas backs up the reducing valve leading to temp. increase

ratings

-it is recommended that a sedation unit should have received an acceptable rating from the ADAs Council on Scientific Affairs -this listing is published in the Journal of the American Dental Association, the Dentist's Desk Reference, and on the ADA website

safety features: reservoir bag

-it may be used to assist or control respiration in emergency situations but more often with a full face mask

manifolds (central system only)

-joins multiple compressed-gas cylinders

demand-flow unit disadvantage 2

-lack of accuracy of the mixer value -percentage of gas delivered is not accurate over the full range of delivery (0% to 100% N2O)

central storage system equipment

-large cylinders are used -multiple treatment areas may be connected by copper piping -if inhalation sedation is used regularly, there is a savings using the larger gas cylinders

regulators location

-located between cylinders of gas and flowmeters on yoke on potable units -located usually on cylinder in central systems

emergency air intake valve location

-located on bag-tee above reservoir bag

safety features: emergency air inlet

-located on top of the bag-tee outlet -the emergency air inlet is maintained in a closed position as long as O2 or N2O-O2 is being delivered -when the flow of gases ceases, the emergency air inlet valve opens, permitting the patient to continue to breathe, now atmospheric air

safety features: diameter index safety system (DISS)

-makes it impossible to attach a low-pressure hose to the wrong outlet on the sedation system -the diameter of the couplings differ significantly and the threading of the attachments differs -makes it physically impossible to accidentally cross the low-pressure hoses and deliver the wrong gas

safety features: pin index safety system

-makes it physically impossible to attach an N2O cylinder to the yoke attachment for O2 -consists of a series of pins -the configuration that differs for each compressed gas and matching series of holes on the cylinders

cylinders

-marked with a metal stamp indicating the date the cylinder was commissioned, dates of testing, the pressure for which the cylinder was designed, insignia of testing facility, and identification of manufacturer -cylinders are designed to handle 1.66 times the usual pressure

nonautomatic manifold

-most common -when a cylinder is empty, it must be physically turned off and new one opened

after grease/oil ignites

-once it ignites, either N2O or O2 although nonflammable, will support the combustion -temperature and pressure within the cylinder increase even further and producing: an explosion, a melting of the valve stem of the cylinder, releasing the contents, or death and serious injuries have occurred

handling compressed gas cylinders 5

-open cylinder valves slowly in a counterclockwise direction -valves must be fully opened to prevent leakage from valve stems

safety features: oxygen flush button

-permits rapid delivery of high flows of O2 to the patient -N2O delivery is automatically stopped when the oxygen flush button is pressed -the button is ideally located on the front of the sedation unit

central storage system with mobile heads

-permits the use of larger compressed-gas cylinders with mobile heads but the inhalation sedation unit sits on a portable stand without a yoke apparatus -it may be moved from treatment room to treatment room -quick connect tubing attaches the unit to O2 and N2O outlets on the wall

continuous-flow unit subgroups

-portable systems -central storage system -central storage system with mobile heads

central storage system with mobile heads recommendations

-recommended for offices in which economics of central storage warrant its instillation but frequency of use of inhalation sedation does justify purchase of heads for all treatment areas

portable systems

-rolling stand compressed-gas cylinders attach at the yoke assembly -used when frequency of use is low or expense of central storage system is prohibitive

manifold safety pressure relief valve

-safety pressure relief valve is also found on manifold -an alarm activates when pressure is too high or low

reservoir bag secondary function

-serve as a monitoring device for respiration, will inflate and deflate with exhalations and inhalations

safety features: minimum oxygen percentage

-sets a minimum of 30% O2 on sedation units -remember that the minimum amount of O2 that must be used when administering N2O must be 20% O2

handling compressed gas cylinders 3

-store cylinders in an area where temperatures do not fluctuate -avoid heat in particular

handling compressed gas cylinders 2

-store full cylinders in vertical position

regulators explosion

-temp. increases can ignite oil, grease, or Teflon if found in this area -this leads to explosion and fire -requires proper care and handling

yokes- circuit of gases

-the "high-pressure system": from cylinder through yoke and into reducing valve -the "low-pressure system": from reducing valve to patient

continuous-flow units advantages

-the 2 major disadvantages of the demand-flow unit are eliminated -eliminates ability to visualize flow of gases and inaccuracy of the mixer value

O2 cylinder pressure

-the pressure in a full tank of O2 is 1800-2100psi -the pressure in a half-full tank of O2 is 900-1100psi -this is because the contents of a tank of O2 contains only gas

central storage system

-the supply of N2O and O2 is located a distance from the area where the gases are delivered -in the treatment area, the inhalation sedation unit/ head will be present along with accessory equipment required for the delivery of the gases -gas cylinders are maintained in a storage area and gases are delivered to treatment area through copper pipes

scavenging system

-the use of a scavenging system with N2O sedation equipment is desirable because it removes any potentially toxic waste gas from the environment

air intake valve normal use

-the valve remains shut but opens automatically once gas flow through the machine is terminated -this prevents patient from feeling suffocated if the unit is not working

what to flowmeters measure

-they measure actual quantity of gas in motion not cylinder pressure -if flow is interrupted, flowmeter will read zero

can demand-flow be used?

-this type of unit falls below the standard of care because it prevents the important practice of titration from occurring

reservoir bag primary function

-to provide a reservoir if respiratory demands of patient exceed gas flow, as when a patient draws a deep breath

regulators function

-to reduce high-pressure gas from cylinder to a pressure safe for patient and sedation unit -to maintain constant gas pressure to flowmeters and to patient regardless of gas pressure contained within the cylinder, important to minimize potential for damage

cylinders color

-uniform color code on all compressed gas cylinders -N2O: light blue -O2: green

handling compressed gas cylinders 1

-use no grease, oil or lubricant of any type to lubricate cylinders valves, gauges, regulators or other fittings that may come into contact with gases -extremely dangerous

what are the cylinders made of?

-usually manufactured from 3/8 inch-thick steel although some cylinders N2O have been made of aluminum -tested every 5 years to ensure integrity with internal hydrostatic pressure, the pressure depending on the size of the cylinder