All about O2
A variety of oxygen interfaces/appliance can be used with a LVN
Aerosol Face Mask Aerosol Face Tent Aerosol Trache Collar (for a TRACHE Pt) Aerosol T-Tube (for patient with an ETT) We'll explore these in Lab
High Flow Devices & Law of Continuity
Law states that as the fluid flows at a constant rate (i.e., 5L/min), the velocity increases when the cross-sectional diameter decreases. Diameter and Velocity are inversely related
High Flow Devices: Fixed Performance
Max Flows: Adults: up to 50lpm Children: 20-30 lpm Neonates: 2-8 lpm
High Flow: High Flow Nasal Cannula
Max Flows: Adults: up to 50lpm Children: 20-30 lpm Neonates: 2-8 lpm
Partial Pressure of Oxygen Abbreviations
Needles: with blood gas Here are a list of partial pressures of oxygen measurements that you will need to become familiar with. We will talk about these frequently and will become a habit in conversation.
O2 CONTRAINDICATIONS:
No specific contraindications to oxygen therapy exist when indications are judged to be present.
Oxygen Enclosures
Oxygen Hood Enclosures Oxygen hood (AKA: Oxyhood): Generally is best method for delivering controlled oxygen to infants Oxygen tent: Regulating cooling and FiO2 can be difficult (very old school)
O2 RISKS & HAZARDS
Oxygen does not come without risks:
Oxygen facts
Range: FiO2 21 - 100____% Anhydrous: without humidity? A drug Requires a physician order Must be monitored for response and effectiveness
High, Low, or Reservoir?... 2 questions
Second :Does the delivered FiO2 remain: fixed or variable ? A FIXED Delivery Device: FiO2 REMAINS STABLE: WILL NOT change under pt changing conditions. Variable devices will VARY under changing patient demands A patient's WOB (increased or decreased) may cause the delivered FiO2 to be diluted or more concentrated, depending on how the patient is breathing. Depends on how much of patient's inspired gas the system supplies When a patient inspires, a flow is generated Pt Faster flow will result in an increased PIF and Vice Versa
Low Flow: NonRebreathing Mask (NRB)
Similar concept as PRB: BUT INCORPORATES TWO VALVES: 1.ONE-WAY VALVE BETWEEN BAG AND FACEMASK IS PRESENT 2.At least 1 one-way valve on the side of mask ALWAYS ENSURE ONE SIDE PORT IS OPEN: SAFETY
O2 RISKS & HAZARDS CONT2
So how much O2 should we use? 1.If patient needs 100% O2, try to limit this FiO2 to < 24hrs (titrate down as soon as possible) 2.Use the minimum FiO2 to achieve the best oxygenation (evidenced by PaO2) and Alleviate Symptoms. This is critical in Neonates: High FiO2 in newborns and premature babies can cause retinal damage: Called Retinopathy of Prematurity (ROP) ALSO: O2 results in vasodilation and may risk INTRAVENTRICULAR HEMMORRHAGE in PREMATURE BABIES (neonates)
So: Why Does a High Flow device need to be able to deliver at least 60LPM total flow?
TO get a pts VE, you will need to multiply their RR x VT You will be given either the VE ... or the RR & VT. An avg VE is 10-20 L/min A patient who is breathing at a higher VE may appear more air hungry and have a higher WOB. See the example that shows a patient breathing at the high end of normal VE will have a PIF of 60LPM. We must choose a device that will MEET his Flow Demands
Low Flow: Reservoir Systems: Anatomical Reservoir
TO understand a reservoir system, let's revisit the concept of our ANATOMICAL RESEVOIR: We all have an INNATE RESEVOIR: our Nasopharynx & Oropharynx Holds small amounts of 100% 02 (50cc) available for next inspiration. THE LAST PART OF EXPIRATION FLOW FROM DEVICE IS STILL ENTERING THE PHARYNX, WHICH ALLOWS FiO2 GAS THAT REMAINS IN THE NASO/ORO PHARYNX to INPSPIRED ON NEXT BREATH. Increases 02 Aids with low-flow devices Pt. Vt and RR influence effectiveness of reservoir
Calculating a Patient PIF
We said PIF = RR x VT Your first pt: has a VT of 600ml and a RR of 12. What is his Flow Demand? PIF Calculation gives you 21.6 L/MIN (NOTE: in this calculation, YOU MUST CONVERT FROM ml to Liters) Your second pt has a VT of 1000ml and a RR of 36. What is his flow demand? PIF Calculation gives you 108 L/MIN Which patient would require High Flow System (#2) or Low Flow (#1)?
AARC INDICATIONS & CONTRAINDICATIONS OF O2
https://www.aarc.org/resources/clinical-resources/clinical-practice-guidelines/
3 Goals of Oxygen Therapy
3 goals: Correct hypoxemia Decrease Symptoms of Hypoxemia Minimize Cardiopulmonary Workload -Let's talk about this: Oxygen raises alveolar and arterial P02 levels when PO2 Levels are low, CV system compensates for hypoxemia by increasing ventilation and CO. DRAW! because hypoxemia causes pulm. Vasoconstriction and pulmonary Hypertension which make right heart work harder. Oxygen can decrease effects on both heart and lungs. Therefore: Oxygen can decrease right heart workload
3 ways to Assess Need for 02 Therapy
3 ways to assess need for O2 ABG results Clinical Need (as indicated in previous slide, or other clinical indications for O2: ie, Carbon Monoxide or Cyanide Poisoning) Physical Assessment indicating O2 Tachypnea/Dyspnea Cyanosis Respiratory Distress Tachycardia Restlessness
VENTURI PRINCIPLE: Fluid (Air) Entrainment
So now we're combining the LAW of CONTINUITY & BERNOULI's PRINICIPLE = VENTURI PRINCIPLE SO, if the Pressure on the Lateral wall of a TUBE that NARROWS, decreases so much, It becomes < surrounding atmospheric pressure This then is NEGATIVE related to the surrounding ATMOSPHERIC PRESSURE IF WE PLACE AN OPENING (HOLE) at the very POINT where the Pressure Decreases: This negative pressure will pull in another fluid into the primary flow when an open tube is placed distal to the constriction (narrowing) = Fluid entrainment! (Gases are also fluids) THIS PRINCIPLE IS USED IN SOME OF OUR OXYGEN DEVICES *the amount of air entrained at these ports varies directly with the size of the port and the velocity of O2 at the jet* The larger the intake ports and the higher the gas velocity at the jet, the more air entrained.
Goal 3: Minimize Cardiopulmonary Workload
Third Goal: Minimize the CardioPulmonary Workload: When patient is hypoxemic: The brain tells the patient to BREATHE MORE to GET MORE OXYGEN TO THE BODY Patient WOB Increases TO do this, the patient increases ventilation (breathing), the Heart's CO increases Low Oxygen causes the pulmonary vessels to constrict (become tighter/smaller - pulmonary hypertension). The right heart has to push the blood against this INCREASED RESTRICTION THEREFORE: Providing Oxygen SHOULD: Decrease the patient's WOB Improve the Workload on the Heart Improve Right Heart ability to push blood into the pulmonary vessels.
Refresher: What are High Flow Systems?
CHARACTERISTICS of a HIGH FLOW: FIXED PERFORMANCE device: High Flow: Fixed Performance: O2% stays consistent regardless of VT or RR as long as flow exceeds pt. flow To be considered High Flow: Fixed Performance Device: Provides all of inspired gas Must meet or exceed patient inspiratory flow (PIF) > 60LPM QUESTION: Which HIGH FLOW devices meet or exceed a PIF? Ventilator ? Yes Air entrainment (venturi) mask? Sometimes Large volume nebulizer? Sometimes (we'll talk about this soon)
O2 is Supportive ONLY Does NOT correct underlying cause
O2 is Supportive ONLY Does NOT correct underlying cause Pts with HYPOXEMIA DUE TO V/Q MISTMATCH or DIFFUSION DEFECT required O2 THERAPY ... UNTIL more definitive therapies TAKE EFFECT!
O2 Toxicity: Vicious Cycle
Oxygen Toxicity is a vicious cycle. A patient who is hypoxemic will need Oxygen - if a High FiO2 is used for a long period of time, it can lead to O2 toxicity, which as we just learned, can cause alveolar damage/collapse/scarring/pulmonary edema. This results in something called Pulmonary Shunt: This is indicated when the ALVEOLI are NOT BEING VENTILATED, but the PULMONARY VESSELS STILL ARE SENDING BLOOD FLOW TO THE NON-VENTILATED ALVEOLI. JUST REMEMBER: A PATIENTS NEED FOR O2 MUST OVERRIDE CONCERS FOR O2 TOXICITY
Other options for varying FiO2:Blender
A BLENDER is another device for providing VARIED FiO2. The device mixes AIR & Oxygen (ranges 21% - 100%) and delivers the FiO2 via a compressed gas the a patient NOT a HIGH FLOW DEVICE. Just an O2 source. This is more typical in the neo-ped setting
Confirm O2 Delivery: O2 Analyzers
As you'll see in the video link, we need to perform a 2 point calibration (high & low) of our O2 Analyzer. 1st: HIGH Point: O2 from Flow Source/Device (99-100% Compressed Pure O2 coming from wall/tank) Place O2 source in closed container (bag) 2nd: Low Point: O2 in the Room (RA) (21%) Remove from contained source and displayed value should fall to 21% Measurements may vary slightly Now ready for analyzing other O2 devices for accuracy
Bernoulli Effect
Continuity law stated that velocity increases as fluid flows through a constriction. So as the fluid speeds up, Bernoulli principles states that LATERAL PRESSURE on the WALL of that TUBE DECREASES
INDICATIONS
Documented hypoxemia as evidenced by; PaO2 <60mmHgor O2 < 90% on RA PaO2 or SaO2 below desirable range for a specific clinical situation The difference between SpO2 & SaO2, is: SpO2 is an estimate of tissue oxygen via pulse oximetry SaO2 is actually the saturation of O2 (to hemoglobin) measured in the arterial blood. 2. Acute care situations where hypoxemia is suspected 3. Severe trauma 4. Acute MI (myocardial infarction) 5. short-term therapy (i.e. Post op)
What is the purpose of the addition of the open reservoir?
Frequently, you will see a 6" reservoir piece of tubing on the end of devices. The purpose of this is to have an additional reservoir for O2 and/or medication. HOWEVER, If a patient has a PIF that EXCEEDS the NEBULIZER FLOW, ... the Pt will entrain the flow from the atmosphere. For example: if you have a LVN set at 100% for a pt, and the LVN is set at 15 lpm, but the pt's PIF is 45 lpm... which side is he going to pull flow from (Nebulizer or Atmosphere?) Will this patient get the 100% O2 you intend to deliver? A reservoir at the end of the patient exceeds nebulizer flow, gas is drawn form the reservoir side.
Concepts & Causes
Hypoxia (low oxygen at the tissue level) vs Hypoxemia (low oxygen in the blood - confirmed by an Arterial Blood Gas: PaO2)
Monitoring the Physiologic Effects of O2
It's IMPORTANT that ALL RTs not only determine what their patient's needs are, but also: - anticipate the best response - ASSESS for response - TITRATE O2 per patient needs Pulse Oximetry is a non-invasive way to monitor our patient's need for/response to oxygen We'll learn more about Pulse Oximetry soon, but for now: - best guiding rule is to titrate O2 to achieve an SpO2 of ≥ 92%
Additional o2 concepts
Some additional concepts we need to understand is the PHYSIOLOGIC CONCEPT of O2 ADMINSITRATION and the EFFECTs in our PATIENTS Administration of FiO2 increases Partial Pressure of Inspired Oxygen (PIO2) RESULTS IN Increased Partial Pressure of ventilated alveoli (PAO2): NOTE big "A" indicates the ALVEOLAR partial pressure of O2 RESULTS IN Gas exchange occurs = PaO2 (arterial ) and saturation of Hemoglobin (SaO2 & SpO2) increases I've provided you abbreviations and definitions on the next slide.
Goal 2: Decrease Signs and Symptoms of Hypoxemia
The second goal is to decrease the signs and symptoms of Hypoxemia Signs and symptoms are a SUBJECTIVE finding. Patient's descriptions, RT's perception Many signs and symptoms are associated with specific lung diseases (i.e., COPD) You will learn to differentiate possible diagnoses with different symptoms. As you ASSESS /REASSESS your patient, when PROVIDING OXYGEN: Anticipated Signs and Symptoms should include: Less DYSPNEA (Med Term: What's Dyspnea? - Feeling of the Shortness of Breath) Improved Mental Function
Goal 1
we previously learned the concept of the partial pressure of Oxygen as PO2. Hypoxemia: is defined as low oxygen in the blood. We said we measure this with an arterial blood gas. Therefore, we add an "a" to the PO2 which represents the O2 in the arteries..., now referred to as the "PaO2." Hypoxemia is verified when the patient's PaO2 is < 60mmHg and is correlated with an SpO2 <90% (SpO2 is a measurement that is estimated through the tissues, called pulse oximetry) We'll learn about SpO2, very soon REMEMBER: that verifying the PaO2 is an OBJECTIVE GOAL Every time that you provide ANY THERAPY, YOU ALWAYS MUST ASSESS YOUR PATIENT FOR THE ANTICIPATED RESPONSE. This will tell you if the therapy you provided is EFFECTIVE.
O2 RISKS & HAZARDS CONT
Additional O2 risks: 2. absorption atelectasis High FiO2 results in collapse of alveoli breathing RA = approximately 79% Nitrogen When FiO2 increased: Nitrogen molecules displaced with O2 molecules If airway obstruction occurs (air can't get out), Hgb continues to pull O2 from Alveolus (into blood) = Alveolar Collapse 3. oxygen toxicity: Long use of High FiO2 can result in major problems DEFINITION: Cellular injury of lung parenchyma and airway epithelium
