Chapter 38 Medical Gas Therapy

Learning Objectives Describe when oxygen therapy is needed. Assess the need for oxygen therapy. Describe what precautions and complications are associated with oxygen therapy. Select an oxygen delivery system appropriate for the respiratory care plan. Describe how to administer oxygen to adults, children, and infants.

Learning Objectives (cont.) Describe how to check for proper function and to identify and correct malfunctions of oxygen delivery systems. Explain how to evaluate and monitor a patient’s response to oxygen therapy. Describe how to modify or recommend modification of oxygen therapy on the basis of patient response. Review how to implement protocol-based oxygen therapy.

Learning Objectives (cont.) Identify what indications, complications, and hazards apply to hyperbaric oxygen therapy. Explain when and how to provide nitric oxide therapy. Identify when and how to administer helium-oxygen therapy. Summarize other forms of medical gas therapy and alternatives to such therapy.

Oxygen Therapy General Goals & clinical objectives Correct documented or suspected acute hypoxemia Decrease symptoms associated with chronic hypoxemia Decrease workload hypoxemia imposes on cardiopulmonary system

Decrease the workload hypoxemia imposes on the cardiopulmonary system All of the following are the major clinical goals and objectives for oxygen therapy, except: Decrease the workload hypoxemia imposes on the cardiopulmonary system Correct documented or suspected acute hypoxemia Prevent hypoxemic induced multiple system failure Decrease the symptoms associated with chronic hypoxemia Answer: C

Oxygen Therapy (cont.) Assessing need for O2 therapy Laboratory documentation PaO2, SaO2, SpO2 Specific clinical problem e.g., patient suspected of carbon monoxide poisoning Clinical findings at bedside Tachypnea, tachycardia, confusion, etc.

Oxygen Therapy (cont.) Precautions & hazards of supplemental O2 Oxygen toxicity Primarily affects lungs & central nervous system Determining factors include PO2 & exposure time Prolonged exposure to high FIO2 can cause infiltrates in lung parenchyma

Oxygen Toxicity

Oxygen Therapy (cont.) Precautions & hazards of supplemental O2 (cont.) Depression of ventilation Occurs in COPD patients with chronic hypercapnia Retinopathy of prematurity Excessive blood O2 levels cause retinal vasoconstriction & necrosis

Oxygen Therapy (cont.) Precautions & hazards of supplemental O2 (cont.) Absorption atelectasis Can occur with FIO2 above 0.50 Patients breathing small tidal volumes at greatest risk

Absorption Atelectasis

Oxygen Therapy (cont.) Precautions & hazards of supplemental O2 (cont.) Fire hazard Fires in O2-enriched environments continue to occur Practitioners in surgery suites & in presence of hyperbaric O2 therapy need to be most careful

Depression of ventilation Retinotopathy of prematurity All of the following are major precautions and hazards of supplemental oxygen therapy, except: Oxygen toxicity Depression of ventilation Retinotopathy of prematurity Oxygen induced encephalopathy Answer: D

Oxygen Therapy (cont.) O2 delivery systems: design & performance 3 basic designs exist Low-flow systems Reservoir systems High-flow systems

Oxygen Delivery Systems

Oxygen Therapy (cont.) Nasal cannula (excluding High-flow version discussed later) Delivers FIO2 of 0.24 to 0.40 Used with flow rates of ¼ to 8 L/min FIO2 depends on how much room air patient inhales in addition to O2 Device is usually well tolerated

Oxygen Therapy (cont.)

Oxygen Therapy (cont.) Nasal catheter Used at flows of ¼ to 8 L/min Delivers FIO2 of 0.22 to 0.45 Rarely used in modern health care facilities today Has been replaced by nasal cannula

Oxygen Therapy (cont.)

Oxygen Therapy (cont.) Transtracheal catheter Surgically placed in trachea through neck by physician Uses 40-60% less O2 to achieve same PaO2 by nasal cannula Used with flow rates of ¼ to 4 L/min Requires careful maintenance & cleaning Complications such as infection are possible

Oxygen Therapy (cont.)

Oxygen Therapy (cont.) Reservoir cannula Designed to conserve oxygen Nasal reservoir Pendant reservoir Can reduce oxygen use as much as 50% to 75% Humidification usually not needed

Oxygen Therapy (cont.)

Oxygen Therapy (cont.) Reservoir masks Most commonly used reservoir systems 3 types Simple mask Partial rebreathing mask Nonrebreathing mask

Oxygen Therapy (cont.)

Oxygen Therapy (cont.)

Oxygen Therapy (cont.) High-flow systems Supply given O2 concentration at flow equaling or exceeding patient’s peak inspiratory flow Can ensure fixed FIO2 Most suitable for patients requiring precise FIO2, with high or variable minute ventilation Include air-entrainment or blending systems Venturi masks Air-entrainment nebulizers

Oxygen Therapy (cont.)

Oxygen Therapy (cont.)

Other Oxygen Delivery Devices Enclosures Oxygen hood (AKA: Oxyhood): Generally is best method for delivering controlled oxygen to infants Incubators (AKA Isolette): Can be used in conjunction with oxyhood Oxygen tent: Regulating cooling & FIO2 can be difficult

Oxygen Therapy (cont.)

Other Oxygen Delivery Devices (cont.) High Flow Nasal Cannula - Provide high FIO2, high relative humidity & positive pressure Demand & Pulse - dose Systems-Conserve by providing flow during inspiration only Bag-Mask Device - Provide 100% FIO2, often during emergencies

Selecting a delivery approach

Oxygen Therapy (cont.)

Air-entrainment (venturi) Non-rebreather mask The most suitable oxygen delivery device for a patient with an unstable minute ventilation, needing a precise, moderate FIO2 is: Nasal cannula Simple mask Air-entrainment (venturi) Non-rebreather mask Answer: C

Transtracheal oxygen system Simple mask Nasal catheter The most suitable oxygen delivery device for a patient who requires a low FIO2, desires to conserve oxygen and objects to appearance of a nasal cannula, is: Pendant cannula Transtracheal oxygen system Simple mask Nasal catheter Answer: B

Physiological effects

Hyperbaric Oxygen Therapy (cont.) Methods of administration HBO is administered in either multiplace or monoplace chamber Multiplace chamber can hold 12 or more people Monoplace chamber can hold only 1 patient

Hyperbaric Oxygen Therapy

Hyperbaric Oxygen Therapy (cont.) Indications 2 most common acute conditions for which HBO is administered by RTs are: Air embolism Carbon monoxide poisoning

Hyperbaric Oxygen Therapy (cont.)

Complications & hazards

Air emboli and CO poisoning Wound healing and gas gangrene The most common indications for hyperbaric oxygen therapy (HBO) administered by RTs are: Air emboli and CO poisoning Wound healing and gas gangrene Neovascularization and wound healing Cardiac anomalies and lung transplantation Answer: A

Other Medical Gas Therapies Nitric oxide therapy Improves blood flow to lung Reduces shunting Improves oxygenation Decreases pulmonary vascular resistance Lower cost alternative drug therapies, including inhaled epoprostenol sodium, are gaining popularity

Nitric Oxide Therapy

Nitric oxide therapy

Nitric oxide therapy

Other Medical Gas Therapies (cont.)

Persistent Pulmonary Hypertension of the Newborn Sickle cell disease All of the following are major indications for Nitric Oxide therapy, except: ARDS Persistent Pulmonary Hypertension of the Newborn Sickle cell disease Cerebral encephalopathy Answer: D

Other Medical Gas Therapies (cont.) Helium-oxygen therapy Value of helium as therapeutic gas is based solely on its low density Can decrease work of breathing for patients with airways obstruction (e.g., asthma, croup, etc.)

Other Medical Gas Therapies (cont.) Heliox therapy Guidelines for use Helium must always be mixed with O2 Heliox can be prepared at bedside or used from premixed cylinders In general, heliox should be delivered to patients via tight-fitting nonrebreathing mask with high flow

Other Medical Gas Therapies (cont.) Heliox therapy (cont.) Troubleshooting & hazards Poor vehicle for aerosol transport Reduces effectiveness of coughing Badly distorts patient’s voice Hypoxemia can be problem

The main indication for heliox therapy is: Upper airway obstruction Pulmonary hypertension Pulmonary embolism Refractory hypoxemia Answer: A

Other Medical Gas Therapies (cont.) Carbon Dioxide-Oxygen (Carbogen) Therapy Not common, but used for: Hiccoughs Carbon monoxide poisoning Preventing complete washout of CO2 during cardiopulmonary bypass Available in mixtures of: 5%:95% or 7%:93%