OXYGEN THERAPY. DR :Gehan Ali. Lecturer of chest Ds Menoufia university

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1 OXYGEN THERAPY DR :Gehan Ali Lecturer of chest Ds Menoufia university

2 O 2 Therapy : Indications Documented hypoxemia as evidenced by PaO 2 < 60 mmhg or SaO 2 < 90% on room air PaO 2 or SaO 2 below desirable range for a specific clinical situation Acute care situations in which hypoxemia is suspected Severe trauma Acute myocardial infarction Short term therapy (Post anaesthesia recovery) Respir Care 2002;47:

3 Indications for Long Term Oxygen Therapy (LTOT): Resting room air: PaO2: < 55 mmhg SaO2: < 88% Resting PaO2 = or SaO2 <89% in the presence of: CHF or P pulmonale in ECG or evidence of P++ in Echo cardiography.

4 MONITORING Physical examination for C/F of hypoxemia Pulse oximetry ABG analysis ph po2 pco2 Mixed venous blood oxygenation

5 ASSESSMENT The need for oxygen therapy should be assessed by 1. monitoring of ABG - PaO2, SpO2 2. clinical assessment findings.

6 PaO2 as an indicator for Oxygen therapy PaO2 : mm Hg : Normal mm Hg : cold, clammy extremities < 60 mm Hg : cyanosis < 40 mm Hg : mental deficiency memory loss < 30 mm Hg : bradycardia cardiac arrest PaO2 < 60 mm Hg is a strong indicator for oxygen therapy

7 Clinical assessment of hypoxia mild to moderate severe CNS : restlessness somnolence, confusion disorientation impaired judgement lassitude loss of coordination headache obtunded mental status Cardiac : tachycardia bradycardia, arrhythmia mild hypertension hypotension peripheral vasoconst. Respiratory: dyspnea increasing dyspnoea, tachypnea tachypnoea, possible shallow & bradypnoea laboured breathing Skin : paleness, cold, clammy cyanosis

8 Methods of Dispensing Oxygen Piped in Cylinder Oxygen concentrator Wall outlets

9 O 2 Delivery systems

10 CLASSIFICATION DESIGNS Low- flow system Reservoir systems High flow system Enclosures PERFORMANCES (Based on predictability and (consistency of FiO 2 provided) Fixed Variable

11 O 2 Delivery devices o Low flow (Variable performance devices ) Nasal cannula Nasal catheter Transtracheal catheter o Reservoir system (Variable performance device) Reservoir cannula Simple face mask Partial rebreathing mask Non rebreathing mask Tracheostomy mask o High flow (Fixed performance devices) Ventimask (HAFOE) Aerosol mask and T-piece with nebulisers

12 Low-Flow Devices

13 Nasal canula nasal catheter Transtracheal catheter

14 Nasal Cannula A plastic disposable device consisting of two tips or prongs 1 cm long, connected to oxygen tubing Inserted into the vestibule of the nose FiO % Flow ¼ - 8L/min (adult) < 2 L/min(child)

15 Nasal Cannula advantage Easy to fix Keeps hands free Not much interference with further airway care Low cost Compliant disadvantage Unstable Easily dislodged Nasal trauma Mucosal irritation FiO2 can be inaccurate and inconsistent

16 Estimation of FiO 2 provided by nasal cannula O 2 Flowrate (L/min Fi O Patient of normal ventilatory pattern - each litre/min of nasal O 2 increases the FiO 2 approximately 4%. E.g. A patient using nasal cannula at 4 L/min, has an estimated FiO2 of 37% ( )

17 Nasal catheter

18 Nasal catheter Merits Good stability Disposable Low cost Demerits Difficult to insert High flow increases back pressure Needs regular changing May provoke gagging, air swallowing, aspiration Nasal polyps, deviated septum may block insertion

19 Transtracheal catheter A thin polytetrafluoroethylene (Teflon) catheter Inserted surgically with a guidewire between 2 nd and 3 rd tracheal rings FiO % Flow ¼ - 4L/min

20 Transtracheal catheter advantage Lower O 2 use Eliminates nasal and skin irritation Better compliance Increased exercise tolerance Increased mobility disadvantage High cost Surgical complications Infection Mucus plugging Lost tract

21 Reservoir systems

22 Reservoir cannula NASAL RESERVOIR PENDANT RESERVOIR

23 Reservoir cannula advantage Lower O 2 use and cost Increased mobility Less discomfort because of lower flow Disavantage Poor compliance Must be regularly replaced (3 weekly) Breathing pattern affects performance (must exhale through nose to reopen reservoir membrane)

24 RESERVOIR MASKS Commonly used reservoir system Three types 1. Simple face mask 2. Partial rebreathing masks 3. Non rebreathing masks

25 Simple face mask Reservoir ml Variable performance device FiO 2 varies with O 2 input flow, mask volume, extent of air leakage patient s breathing pattern FiO 2 : 40 60% Input flow range is 5-8 L/min Minimum flow 5L/min to prevent CO 2 rebreathing

26 Face mask Adventage Moderate but variable FiO2. Good for patients with blocked nasal passages and mouth breathers Easy to apply Disadvantage Uncomfortable Interfere with further airway care Proper fitting is required Risk of aspiration in unconscious pt Rebreathing (if input flow is less than 5 L/min) O 2 Flowrate (L/min) Fi O

27 Partial rebreathing mask O 2 Exhalation ports + Reservoir No valves Mechanics Exp: O2 + first 1/3 of exhaled gas (anatomic dead space) enters the bag and last 2/3 of exhalation escapes out through ports Insp: the first exhaled gas and O2 are inhaled FiO % FGF > 8L/min

28 Non-rebreathing mask One-way valves O 2 Has 3 unidirectional valves Expiratory valves prevents air entrainment Inspiratory valve prevents exhaled gas flow into reservoir bag FiO FGF 10 15L/min To deliver ~100% O 2, bag should remain inflated Reservoir Factors affecting FiO 2 air leakage and pt s breathing pattern

29 The non rebreathing mask

30 Tracheostomy Mask Used primarily to deliver humidity to patients with artificial airways. Variable performance device

31 High-Flow systems Air entrainment devices Blending systems

32 Air entrainment devices Based on Bernoulli principle A rapid velocity of gas exiting from a restricted orifice will create subatmospheric lateral pressures, resulting in atmospheric air being entrained into the mainstream.

33 Mechanism of Air entrainment devices exhaled gas oxygen room air

34 Approximate Air Entrainment Ratio and Gas Flows for different Fio 2 Fio 2 (%) Ratio Recommended O 2 Flow (L/min) Total Gas Flow (to Port) (L/min) : : : : : : :

35 2 most common air-entrainment systems are 1. Air-Entrainment mask (venti-mask) 2. Air-Entrainment nebulizer

36 Venturi / Venti / HAFOE Mask Mask consists of a jet orifice around which is an air entrainment port. FiO 2 regulated by size of jet orifice and air entrainment port FiO2 Low to moderate ( ) HIGH FLOW FIXED PERFORMANCE DEVICE

37 Varieties of Venti Masks A fixed Fio 2 model A variable Fio 2 model

38 Air entrainment nebulizer Have a fixed orifice, thus, air-to-o2 ratio can be altered by varying entrainment port size. Fixed performance device Deliver FiO2 from % Max. gas flows 14-16L/min Device of choice for delivering O2 to patients with artificial tracheal airways. Provides humidity and temperature control

39 Air entrainment nebulizer Aerosol mask Face tent Tracheostomy collar T tube

40 Blending systems With a blending system, separate pressurized air and oxygen sources are input. The gases are mixed either manually or with a blender FiO % Provide flow > 60L/min Allows precise control over both FiO 2 and total flow output - True fixed performance devices OXYGEN BLENDER

41 Oxygen tent Hood Incubator ENCLOSURES

42 OXYGEN TENT Consists of a canopy placed over the head and shoulders or over the entire body of a patient FiO 2 2 Variable performance device Provides concurrent aerosol therapy Disadvantage Expensive Cumbersome Difficult to clean Constant leakage Limits patient mobility

43 OXYGEN HOOD An oxygen hood covers only the head of the infant O2 is delivered to hood through either a heated entrainment nebulizer or a blending system Fixed performance device Fio % Minimum Flow > 7L/min to prevent CO2 accumulation

44 INCUBATOR Incubators are polymethyl methacrylate enclosures that combine servo-controlled convection heating with supplemental O2 Provides temperature control FiO2 flow of 8-15 L/min Variable performance device

45 Hyperbaric O 2 Therapy (HBOT)

46 DEFINITION A mode of medical treatment wherein the patient breathes 100% oxygen at a pressure greater than one Atmosphere Absolute (1 ATA) 1 ATA is equal to 760 mm Hg at sea level

47 Physiological effects of HBO Bubble reduction ( boyle s law) Hyperoxia of blood Enhanced host immune function Neovascularization Vasoconstriction

48 INDICATIONS OF HBOT ACUTE CONDITIONS Decompression sickness Air embolism Carbon monoxide poisoning Severe crush injuries Thermal burns Acute arterial insufficiency Clostridial gangrene Necrotizing soft-tissue infection Ischemic skin graft or flap CHRONIC CONDITIONS Radiation necrosis Diabetic wounds of lower limbs Refratory osteomyelitis Actinomycosis (chronic systemic abscesses)

49 METHODS OF ADMINISTRATION of HBOT

50 Problems with HBOT Barotrauma Ear/ sinus trauma Tympanic membrane rupture Pneumothorax Oxygen toxicity Fire hazards Clautrophobia Sudden decompression

51 Complications of Oxygen therapy

52 Complications of Oxygen therapy 1. Oxygen toxicity 2. Depression of ventilation 3. Retinopathy of Prematurity 4. Absorption atelectasis 5. Fire hazard

53 How much O2 is safe? 100% - not more than 12hrs 80% - not more than 24hrs 60% - not more than 36hrs Goal should be to use lowest possible FiO2 compatible with adequate tissue oxygenation

54 Thank you