Pharmaceutical and Medical Gases Information
Pharmaceutical and medical gases are fluids manufactured specifically for the medical, pharmaceutical manufacturing, and biotechnology industries. They are frequently used to synthesize, sterilize, or insulate processes or products which contribute to human health. Pharmaceutical gases are also inhaled by patients in a technique known as gas therapy.
Pharmaceutical and Medical Gases Operation
Gases used for human healthcare are strictly controlled by both legislation and industrial standards so as to not impair human physiology. Gases of this nature may be manufactured as pure gases or as compounds, but are always filtered to the highest quality possible. The application of each individual gas determines its production and distribution. Medical-grade gases are used in the following applications:
In the production of pharmaceutical merchandise and medicines. They may be used in the synthesis of these items, to sterilize such items, to test the item's packaging, or to insulate them from undesirable environmental effects such as oxidation.
As an analytical agent, to calibrate medical devices or to diagnose a patient by exposing cultures or a biopsy to the gas and examining the reaction.
As a therapy, in which the gas is prescribed as an anesthetic, drug delivery agent, or remedy for an occurring illness.
As an atmosphere in environments in which air composition must be regulated.
As a pneumatic power source for surgical and dental tools.
Medical gases are provided by licensed manufacturers who meet the quality controls which have been established by a jurisdiction's prescription drug regulating agency. Medical gases must be extremely pure, with at least 99.995 percent of the gas congruent to how it is identified. With the exception of medical-grade oxygen, all medical gases are delivered in compressed gas cylinders constructed of aluminum, stainless steel, or some other noncorrosive and nonreactive metal.
Since medical gases are used in healthcare facilities, pipelines are routed from a cylinder storage location, through a gas manifold, and to the rest of the facility wherever access to medical gases is critical to patient care. Pipelines are devoted to a particular type of gas, and these systems will also include a medical vacuum and waste anesthesia exhaust system. Lines are accessible by outlets located around the facility. The proper installation and maintenance of these gas lines is critical to patient care. Many professionals contribute to this system, including anesthesiologists, pharmacists, nurses, engineers, maintenance personnel, and gas suppliers.
Accompanying these pipeline systems are various alarms, gauges, and testing instruments to ensure that the pipeline maintains pressure and flow. Occasionally, pipelines may need to be serviced to maintain service.
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Within medical facilities, gases are introduced to a patient's airway most often by the use of a medical ventilator and/or continuous-flow anesthesia machine. After these machines have been attached to the pipeline outlet, the gas delivered to the machine is vaporized into the correct ratio and administered to the patient via a mask which delivers the gas to the patient's mouth and nose, or by a nasal set which inserts the gas right into the patient's nasal passageway. Other means of introducing the gas to the patients lungs include tracheostomy tubes, laryngeal masks, and endotracheal tubes. Various gauges and testing equipment guarantee the proper flow and ration of the medical gas being administered to the patient. Backup systems, including a reserve gas storage and components for manual ventilation, can be found within these life-support devices.
Production and Atmosphere
Medical gases are occasionally valued for their ability to expel other gaseous fluids from a container or environment. Most often, nitrogen or carbon dioxide is introduced to a pharmaceutical product to reduce oxygen and humidity within the packaging environment, both of which greatly contribute to the decay and ineffectiveness of the drug. Furthermore, gases may be used to suspend cells and tissues in a cryogenic state after freezing, as is the case with nitrogen.
Most often, gases are used to search for leaks in fluid handling equipment. Blood samples are often examined for their ability to carry oxygen and carbon dioxide, and the devices used to measure these samples require a known constant for calibration. Cell cultures may be incubated in certain atmospheres to determine diagnoses.
Some medical hand tools, especially those used by dentists and dental hygienists, utilize medical air as the power source for the instrument. In these regards, the air must be absolutely pure and medical-grade gases are required.
Types of Pharmaceutical and Medical Gases
The following gases and gas compounds are frequently used in the healthcare industries. Gases manufactured for medical use may be identified by the acronym "USP," which represents that they adheres to the United States Pharmacopeia Convention. Most of the following gases have system pressures of about 50 to 55 psi to enhance breathability.
Due to the quantity in which most healthcare facilities use medical air, it is most often produced on-site. Its colorless and odorless composition is 78% nitrogen, 21% oxygen, and a remainder of trace elements. It can be drawn into the building from a roof vent via a compressor, where it is routed through a contaminant filter, as well as dehumidifying and cooling equipment, and then stored in a stainless steel reservoir. Hospital staff access medical air pipelines through various valves and outlets. If a locality has poor air quality, it may be created by mixing manufactured oxygen and nitrogen.
The use of medical-quality air is limited; it cannot be used for anything other than human respiration or the calibration of devices which contribute to human respiration. This includes the transportation of inhaled medications and anesthetics; the respiration of patients who are under anesthesia or utilize a mechanical ventilator; or as the pneumatic gas which powers the bellows of critical care ventilators. Pipelines, valves, and other components of medical-grade gas are indicated by yellow labels with black text.
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Oxygen is essential to the life functions of animals and plants. In humans, oxygen is carried to tissue by hemoglobin in red blood cells, where it assists in the metabolism of the chemical bonds from nutrients. Oxygen therapy is used in several applications: to supplement the breathing of patients whose respiratory system has become comprised from ailments such as chronic obstructive pulmonary disease, bronchitis, or emphysema; to treat patients who need resuscitation or who are suffering from hemorrhage, shock, convulsions or other trauma; to administer atomized, liquid medication into the lungs; or as a treatment itself, due to pure oxygen's vasoconstrictive properties.
Medical oxygen used in hospitals or other large healthcare facilities is frequently provided by a vacuum-insulated evaporator. In this instance, liquid oxygen is supplied to the facility and kept at a temperature which assures a liquid state. This reserve is drawn from and the oxygen is fractionally distilled to turn it back into a gas. For patients who need access to O2 at home, gas cylinders or oxygen concentrators are available and provide medical oxygen at lower volumes. Medical oxygen is frequently represented by green or white labels, and exceptional care must be taken around pure oxygen due to its high combustibility. Furthermore, it cannot come into contact with hydrocarbon materials.
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Carbon Dioxide (CO2)
Since carbon dioxide is a waste byproduct of human respiration, its pharmaceutical uses are limited to: as a gas for noninvasive surgery, to inflate and stabilize body cavities for increased visibility and to increase blood flow to the brain; to remedy bronchial spasms; to stimulate respiration, since the need to release CO2 is greater than the need to inhale O2; and for clinical and physiological examinations. Carbon dioxide is administered to the patient via face mask. Carbon dioxide is also used as an atmosphere for organs which are artificial or awaiting transplant, and as a tracer gas for pharmaceutical package testing.
Carbon dioxide is supplied to facilities via compressed gas cylinders, where it remains as a pressurized liquid until extracted. Health facilities use grey labels to indicate carbon dioxide.
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Nitrogen's inert characteristics make it a versatile gas in pharmaceutical applications. It is regularly used as a pressurizing agent. Tanks, pipelines, hoses, vessels, and other process equipment can be tested for leaks with nitrogen gas. It can also be used to dispense or transfer nearly any type of fluid from storage tanks or reservoirs. Its use as an asphyxiant makes it suitable for purging volumes of other corrosive or volatile gases. It is used as a blanketing agent when packaging pharmaceutical medications. Liquid nitrogen is also used to instantly freeze biological samples, such as agricultural, flora, and fauna specimens, as well as human blood, sperm, embryos, and bone marrow, without degrading specimen integrity. It is also used in dermatology to treat cutaneous micro-trauma. Finally, nitrogen may be elected to power pneumatically-controlled surgical and dental handtools.
Nitrogen is typically packaged in gas cylinders as a pressurized liquid, but nitrogen generators are available. Black labels indicate nitrogen pipelines and tanks. Nitrogen pressures can reach 174 psi.
Medical nitrogen cylinder; medical nitrogen generator
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Nitrous Oxide (N2O)
Nitrous oxide is valued for its contributions as a weak general anesthetic, where it is prescribed to patients via facemask in a ratio with oxygen. At least 21% of the gas mixture must be oxygen. It is used as an anesthetic in surgery and dental applications. N2O also helps alleviate anxiety in patients. Nitrous oxide is commonly referred to by its nickname "laughing gas" because of its intoxicating effects, and when used as an analgesic it is usually a precursor to other intravenous or oral painkillers. It is considered an alternative therapy for narcotic addiction.
Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. The N2O byproduct is filtered to eliminate impurities and refrigerated to induce liquefaction. It will remain as a liquid at room temperature in a pressurized cylinder, which is how it is distributed. Labels for nitrous oxide are light blue in color.
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Nitric Oxide (NO)
Nitric oxide is a powerful vasodilator, essential signaling molecule, and also a free radical. Since it dilates blood vessels, it is commonly prescribed to patients who suffer from circulation or heart ailments; however, it is prescribed as nitroglycerin and amyl nitrate pills which are metabolized into NO. In fact, the only instance for a NO gas prescription, which needs to be implemented in equal parts with oxygen, is for neonatal patients who suffer from pulmonary hypertension or post-meconium aspiration.
There is no standardized label color for nitric oxide systems; the only designation is that it remains separate from established colors. Nonetheless, nitric oxide lines and cylinders are frequently labeled with teal and black labels.
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Helium is most commonly used in respiratory therapies. Its low density makes it easy to respire and it is provided as an oxygen/helium mixture, most commonly in a 21%/79% or 30%/70% ratio, known as heliox. Its low temperature, when compressed, cools metal components used in magnetic resonance imaging (MRI) machines. It is also used in some cryogenic applications.
Helium is manufactured from the liquefaction of natural gas. It is provided to customers in compressed cylinders which are outfitted with brown or brown and green color-coded indicators.
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Medical-quality xenon is used for hyperpolarized magnetic resonance imaging (HPMRI) and xenon-enhanced computed tomography. Xenon is beginning to replace nitrous oxide as an anesthetic because it does not inebriate patients and reduces the potential for nausea. Recent studies have indicated that xenon can protect neurological and cardiovascular systems from oxygen deprivation and overstimulation during bypass surgeries. Xenon is also useful for medical imaging applications as it can be used to visualize cavities, airways, and soft tissue.
Xenon is relatively expensive for USP-grade gas and until recently was used sparingly; new harvesting techniques have improved its economic viability. Since xenon is largely inert, bright green labels typically indicate xenon supplies, but no set color code has been established.
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Argon gas has limited employment in the medical and biotechnology sector. It is occasionally used in pharmaceutical packaging to retard or prevent the oxidation of prescription drugs where nitrogen may conflict. Blue argon lasers--ion lasers which utilize argon as the lazing medium--are used to weld arteries, destroy tumors, and correct eye defects. An argon and oxygen mix, known as argox, may be used to deplete excessive amounts of nitrogen in the bloodstream. Like most other medical gases, argon is supplied to the end user via cylinders which will have dark green labels.
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Recent studies indicate hydrogen gas has an emerging role in gas therapies. Minute amounts of inhaled hydrogen gas are shown to have antioxidant, anti-inflammatory, and anti-apoptotic protective effects on biological tissues. Hydrogen cylinders are indicated with red labels, but hydrogen gas used as a remedy is not widespread.
Ailments which can benefit from H gas therapy
Image credit: Dixon et al. via Medical Gas Research
International Color Codes
The accompanying diagram indicates the color codes for medical gases based on which standard is adhered.
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The equipment with which medical gases are applied to a patient, production process, or other task is strictly controlled. More than 225 standards relating to pharmaceutical and medical gases are available through the IHS Global Standards Store.
Due to the fact that all medical gases are considered drugs which are only available by prescription, the standards with which they are governed are strictly controlled by a nation's pharmacological oversight agency. Specifically, in the United States, medical gases are under the scrutiny of the United States Pharmacopeia and National Formulary, whose recommendations are legally enforced by the Food and Drug Administration. The FDA's Compressed Medical Gas Guidelines and Manufacturing Guidelines for Medical Gases serve as the foremost instruments of patient safety.
In addition, various manufacturer and healthcare trade associations establish standards on their own. Some examples would be the Compressed Gas Association's M-1, Standards for Medical Gas Supply Systems at Healthcare Facilities and the British Compressed Gases Association's assorted standards on the handling and use of compressed gases.
Due to the fact that medical gases can be combustible or act as oxidants, medical gas systems must adhere to NFPA 99.
Finally, all individuals who install or maintain medical gas systems must receive appropriate training and complete the Medical Gas Installer Exam. Those who administer or prescribe pharmaceutical-grade gases undergo extensive medical training and licensing programs.
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