Medical Gas Therapy PDF

Chapter 42 Medical Gas Therapy Low-Flow System 1  Learning Objectives (1 of 3) ˜ Describe when oxygen (O2) therapy is needed. ˜ Assess the need for O2 therapy. ˜ Describe what precautions and complications are associated with O2 therapy. ˜ Select an O2...

Chapter 42 Medical Gas Therapy Low-Flow System 1  Learning Objectives (1 of 3) ˜ Describe when oxygen (O2) therapy is needed. ˜ Assess the need for O2 therapy. ˜ Describe what precautions and complications are associated with O2 therapy. ˜ Select an O2 delivery system appropriate for the respiratory care plan. 2  Learning Objectives (2 of 3) ˜ Describe how to administer O2 to adults, children, and infants. ˜ Describe how to identify and correct malfunctions of O2 delivery systems. ˜ Assess and monitor a patient's response to O2 therapy. ˜ Describe how and when to modify or recommend modification of O2 therapy. 3  Learning Objectives (3 of 3) ˜ Describe how to implement protocol-based O2 therapy. ˜ Identify the indications, complications, and hazards of hyperbaric O2 therapy. ˜ Identify when and how to administer specialty therapeutic gases. 4  Oxygen Therapy ˜ The overall goal of O2 therapy: Ø Maintain adequate tissue oxygenation Ø Minimizing cardiopulmonary work ˜ Clinical objectives for O2 therapy: Ø Correct documented or suspected acute hypoxemia Ø Decrease symptoms associated with chronic hypoxemia Ø Decrease the workload hypoxemia imposes on the cardiopulmonary system 5  Assessing the Need for Oxygen Therapy Indications ˜ Documented or suspected hypoxemia as evidenced by Ø PaO2 less than 60 mm Hg or SaO2 less than 90% in subjects breathing room air Ø PaO2 or SaO2 below desirable range for a specific clinical situation ˜ Severe trauma ˜ Acute myocardial infarction (MI) ˜ Post-Op like short-term therapy or surgical intervention (e.g., postanesthesia recovery) 6 7  Hazards of Oxygen Therapy ˜ Ventilatory depression ˜ Absorption atelectasis Ø FIO2 > 50% may cause ˜ Retinopathy of atelectasis due to oxygen Prematurely (ROP) replace nitrogen. ˜ Oxygen toxicity ˜ Depression of ˜ Fire hazard ventilation. ˜ Contamination Ø Pao2 > 60 mmHg may depress ventilation with chronic hypercapnia. 8  Precautions & hazards of supplemental O2 (cont.) Ø 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 9  Precautions & hazards of supplemental O2 (cont.) Ø Depression of ventilation Occurs in COPD patients with chronic hypercapnia Ø Retinopathy of prematurity Excessive blood O2 levels cause retinal vasoconstriction & necrosis Ø Absorption atelectasis Can occur with FIO2 above 0.50 Patients breathing small tidal volumes at greatest risk 10 Absorption Atelectasis Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 11  Oxygen Therapy (cont.) ˜ Precautions & hazards of supplemental O2 (cont.) Ø 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 12  13 Copyright © 2017 by Mosby, an imprint of Elsevier Inc.  TABLE 42-3 Page: 912&913 14  Oxygen Delivery Systems ˜ O2 delivery systems: design and performance Ø Three basic designs exist 1. Low-flow systems 2. Reservoir systems 3. High-flow systems ˜ Clinical performance ultimately determines how the device is used Ø How much O2 can the system deliver? Ø Does the delivered FiO2 remain fixed or vary under changing patient demands? 15 Differences between O2 delivery systems 16  Low Flow System Low Flow Devices (Variable Performance) ˜ FiO2 can vary with: Ø Patient’s respiratory rate and pattern Ø Flow of gas from the equipment Ø Equipment reservoir ˜ Does NOT fully meet patient’s inspiratory demand Ø Needs additional mixing with room air 17  Low Flow System Cont. ˜ Low-flow devices include: Nasal cannula Nasal catheter (no longer used) Transtracheal catheters 18  Low-Flow Systems: Nasal Cannula ˜ 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 ˜ A humidifier is used when the input flow is greater than 4 L/min 19  Low-Flow Systems: Nasal Catheter ˜ Generally limited to short-term O2 administration during specialized procedures Ø A bronchoscopy ˜ Used at flows of ¼ to 8 L/min ˜ Delivers FiO2 of 0.22 to 0.45 ˜ Should be replaced with a new one at least every 8 hours Ø Placed in the opposite naris ˜ Has been replaced by nasal cannula 20  Oxygen Therapy: Transtracheal Catheter ˜ Surgically placed in trachea through neck by physician ˜ Uses 40% to 60% less O2 to achieve same PaO2 by nasal cannula ˜ Used with flow rates of ¼ to 4 L/min ˜ Requires careful maintenance and cleaning ˜ Complications such as infection are possible 21  Performance Characteristics of Low-Flow Systems (1 of 3) ˜ Provide O2 concentrations ranging from 22% at 1 L/min to 60% at 15 L/min ˜ The range of 22% to 45% is based on 8 L/min as the upper limit of comfortable flow ˜ Concentration delivered by a low-flow system varies with the amount of air dilution ˜ Estimation FiO2 provided by low-flow systems Ø Each 1 L/min of nasal O2 increases FiO2 approximately 4% 22  Performance Characteristics of Low-Flow Systems (2 of 2) ˜ Increases FiO2 ˜ Decreases FiO2 Ø Higher O2 input Ø Lower O2 input Ø Mouth-closed breathing* Ø Mouth-open breathing* Ø Low inspiratory flow Ø High inspiratory flow Ø Low tidal volume Ø High tidal volume Ø Slow rate of breathing Ø Fast rate of breathing Ø Small minute ventilation Ø Large minute ventilation Ø Long inspiratory time Ø Short inspiratory time Ø High I:E ratio Ø Low I:E ratio 23  Troubleshooting Low-Flow Systems ˜ Common problems with low-flow O2 delivery systems include: Ø Inaccurate flow Ø System leaks and obstructions Ø Device displacement Ø Skin irritation Ø The problem of inaccurate flow is greatest when low-flow flowmeters (≤3 L/min) are used 24  Reservoir Systems: Cannulas ˜ Designed to conserve oxygen Ø Nasal reservoir Ø Pendant reservoir ˜ Can reduce oxygen use as much as 50% to 75% ˜ Humidification usually not needed 25  Reservoir Systems: Masks ˜ Most commonly used reservoir systems ˜ Three types 1. Simple mask 2. Partial rebreathing mask 3. Nonrebreathing mask 26  Simple Mask ˜ The input flow range for an adult simple mask is 5 to 10 L/min Ø At a flow less than 5 L/min, the mask volume acts as dead space and causes carbon dioxide (CO2) rebreathing ˜ FiO2 range is 0.35 to 0.50 Ø Air dilution easily occurs during inspiration through its ports and around its body, provides a variable FiO2 Ø FiO2 varies depending on the O2 input flow, the mask volume, the extent of air leakage, and the patient’s breathing pattern 27  Partial Rebreathing Mask ˜ Because the bag increases the reservoir volume, provides higher FiO2 capabilities than a simple mask Ø A partial rebreathing mask has no valves Ø During inspiration, source O2 flows into the mask and passes directly to the patient Ø During exhalation, source O2 enters the bag. ˜ The input flow range for an adult partial rebreathing mask is a minimum of 10 L/min to prevent bag collapse on inspiration ˜ FiO2 range is 0.40 to 0.70 28  Nonrebreathing Mask (1 of 2) ˜ More commonly used than a partial rebreathing mask ˜ The input flow range for an adult partial rebreathing mask is a minimum of 10 L/min to prevent bag collapse on inspiration ˜ FiO2 range is 0.60 to 0.80 29  Nonrebreathing Mask (2 of 2) ˜ Prevents rebreathing with one-way valves Ø An inspiratory valve sits on top of the bag, and expiratory valves cover the exhalation ports on the mask body Ø During inspiration, slight negative mask pressure closes the expiratory valves, preventing air dilution Ø At the same time, the inspiratory valve on top of the bag opens, providing O2 to the patient Ø During exhalation, valve action reverses the direction of flow 30 31  Troubleshooting Reservoir Systems ˜ Common problems with reservoir masks include: Ø Device displacement Ø System leaks and obstructions Ø Improper flow adjustment Ø Skin irritation 32  Oxygen Conservation Device ˜ Pulse demand oxygen delivery system Ø Delivers oxygen only during inspiration Ø Can be used with nasal cannulas, nasal catheters, and transtracheal oxygen catheters Ø Delivers flows equivalent to 1 to 5 L/min Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 33 High Flow System Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 34  High Flow System ˜ High flow (fixed performance) Ø Provides flow rate adequate to meet patients’ inspiratory flow needs ˜ Provides a relatively constant (fixed) FIO2 by supplying all the gases the patient requires without further dilution of room air Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 35  High Flow System Cont. Ø Delivers a FIO2 of 0.24 to 1.0, regardless of patient’s breathing pattern. Ø High-flow devices include: Air entrainment mask, venturi ,or high airflow with oxygen enrichment (HAFOE) Oxygen hoods Incubators Oxygen tents ˜ High volume aerosol and humidifiers through (face mask and tracheostomy collars devices) also be considered high flow oxygen devices. Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 36 Air Entrainment Mask (Venturi Mask) ˜ Oxygen delivered through an orifice; this increases flow rate of gas ˜ A decrease in pressure on other side of orifice ˜ Causes air from atmosphere to be entrained ˜ Oxygen and air mixes to obtain precise concentration ˜ Primary application: to provide oxygen therapy for patients with COPD Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 37 Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 38 Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 39 Air:Oxygen Ratios Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 40 Air Entrainment Mask Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 41  Air Entrainment Mask (Cont.) ˜ Total flow from mask is determined by multiplying oxygen flow rates by number of parts ˜ Cannot be used with humidifier due to back pressure; humidity can be added by attaching collar at air entrainment ports Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 42  Oxygen Hoods ˜ Encloses infant’s head ˜ Generally is best method for delivering oxygen to infants ˜ The FIO2 should be monitored at same level as infant’s nose ˜ Noise levels inside hood can be problematic ˜ Must analyze O2 near head! Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 43 Oxygen Hoods (Cont.) Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 44  Incubators ˜ Regulate temperature, humidity, and FIO2 of infants’ environment ˜ Include port to regulate FIO2 : Ø If port is open, FIO2 is 0.40 or less Ø If port is closed, FIO2 is 0.40 or higher ˜ FIO2 inside incubator can vary significantly due to opening chamber for nursing care ˜ Hood inside incubator may be necessary to maintain consistent FIO2 Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 45 Incubators (Cont.) Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 46  Oxygen Tents ˜ Uses a frame and a large , soft plastic material to enclose the patient. ˜ Used in pediatrics especially with croup. ˜ Tents receive O2 from a high flow aerosol system. ˜ FIO2 is difficult to be controlled because of large volume Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 47  Oxygen Blenders and Mixers ˜ Mixes 50 psig source of oxygen and air to obtain precise FIO2 ˜ Alarms signal failure of either compressed gas source ˜ Pressure change of 10 psig will activate alarm Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 48  Oxygen Blender ˜ Oxygen Blenders and Mixers: ˜ Mixes 50 psig source of oxygen and air to obtain precise FIO2 ˜ Alarms signal failure of either compressed gas source ˜ Pressure change of 10 psig will activate alarm Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 49 Oxygen Blender cont. Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 50  Other Oxygen Delivery Devices Courtesy of Fisher & Paykel Healthcare, Inc., Irvine, From Henry MC, Stapleton ER: EMT prehospital care, revised ed 4, California. St. Louis, 2009, Mosby. Bag-Mask Device High Flow Nasal Cannula Provide 100% FIO2, often during Provide high FIO2, high relative humidity & positive emergencies pressure 51 Copyright © 2017 by Mosby, an imprint of Elsevier Inc. 52