Sanders: Mosby's Paramedic Textbook, Revised 3 rd Edition PowerPoint Lecture Notes Chapter 19: Airway Management and Ventilation

Transcription

1 Sanders: Mosby's Paramedic Textbook, Revised 3 rd Edition PowerPoint Lecture Notes Chapter 19: Airway Management and Ventilation Chapter 19 Airway Management and Ventilation Objectives Distinguish between respiration, pulmonary ventilation, and external and internal respiration Explain mechanics of respiration Relate partial pressures of gases in blood and lungs to atmospheric gases Describe pulmonary circulation Explain process of gas exchange and transfer in the body Objectives Describe voluntary, chemical, and nervous regulation of respiration Discuss assessment and management of airway obstruction Outline causes and effects and prevention of pulmonary aspiration Describe indications, contraindications, and techniques of oxygen delivery 1

2 Objectives Discuss methods of ventilation Describe manual airway maneuvers and mechanical airway adjuncts Describe assessment techniques and devices to ensure oxygenation, ET tube placement, and elimination of CO 2 Explain airway assessment of the child Given a scenario, identify alterations in oxygenation and ventilation Scenario An elderly black male complained of a severe headache and then lost consciousness and slumped over in his chair. When you arrive, he is snoring, his eyes are closed, and he flexes slightly in response to painful stimulus. He is breathing 8 times per minute, has an oxygen saturation of 81%, and an end-tidal CO 2 of 60 mm Hg. His blood pressure is 160/100 and his heart rate is 50 bpm. Discussion What manual airway maneuver should be attempted initially? Which findings indicate a problem with airway, oxygenation and/or ventilation? What airway adjuncts should be used during his care? How should this patient be oxygenated? What other assessments should you do? 2

3 Upper Airway Anatomy Pharynx Nasopharynx Oropharynx Larynx Thyroid cartilage Glottic opening Arytenoid cartilage Pyriform fossae Cricoid ring Lower Airway Anatomy Function Exchange of O 2 and CO 2 Location Trachea Bronchi and bronchioles Alveoli Lungs Differences in Pediatric Airway Pharynx Trachea Chest wall 3

4 Respiration and Ventilation Respiration Exchange of oxygen and carbon dioxide between an organism and the environment External respiration Transfer of oxygen and carbon dioxide between inspired air and pulmonary capillaries Internal respiration Transfer of oxygen and carbon dioxide between peripheral blood capillaries and tissue cells Pressure Changes and Ventilation Gas flows from an area of higher pressure or concentration to an area of lower pressure or concentration Pressure gradient Required for gas to flow into lungs Produced by differences in: Atmospheric pressure Intrapulmonic pressure Intrapleural (intrathoracic) pressure Chest wall expands Inspiration Lung space increases Pressure gradient causes gas flow into lungs 4

5 Chest wall relaxes Expiration Elastic recoil causes thorax and lung space to decrease in size Pressure gradient is created in thoracic cavity Pressure Changes During Inspiration and Expiration Inspiration and Expiration Muscles of respiration Compliance Work of breathing Pulmonary surfactant Airway resistance Structural changes in lungs or thorax 5

6 Mechanics of Breathing Muscles of Ventilation Muscles of Ventilation 6

7 Lung Volumes and Capacities Anatomical dead space Physiological dead space Tidal volume Reserve volume Inspiratory reserve volume Expiratory reserve volume Residual volume Lung Volumes and Capacities FiO 2 Percentage of oxygen in inspired air (increases with supplemental oxygen) Commonly documented as a decimal (e.g., FiO 2 = 0.85) 7

8 Pulmonary Capacities Minute Volume/ Minute Alveolar Ventilation Minute volume Tidal volume x Respiratory rate Minute alveolar ventilation Amount of inspired gas available for gas exchange in 1 minute Total pressure Gas Pressures Partial pressure Water vapor pressure 8

9 Partial Pressure of Gases in Air Pulmonary Circulation Exchange and Transport of Gases Diffusion Pulmonary circulation 9

10 Exchange and Transport of Gases Concentration of gas determined by its partial pressure and solubility in liquid Pulmonary Gas Exchange Systemic venous blood enters pulmonary capillaries High in PCO 2 and low in PO 2 O 2 molecules diffuse From alveoli (where oxygen is more concentrated) Into blood (where it oxygen less concentrated) CO 2 moves From blood (where it is more concentrated) Into alveoli (where it is less concentrated) Gas Exchange Structure of the Lung 10

11 Respiratory Membrane Thin tissue layer separates pulmonary capillary blood from alveolar air Alveolar wall, interstitial fluid, and wall of pulmonary capillary Oxygen Content of Blood O 2 saturation % of hemoglobin saturated Normally ~98% Oxygen in blood Bound to hemoglobin SaO 2 Dissolved in plasma PaO 2 Oxy-Hemoglobin Dissociation Curve 11

12 Oxy-Hemoglobin Dissociation Curve In exercising tissues, percentage saturation of hemoglobin can decrease to 25% Results in release of 75% of transported oxygen Carbon Dioxide Content of Blood CO 2 is byproduct of cellular work Cellular respiration Carbon dioxide transported in blood in: Plasma (8%) Blood proteins (20%) Bicarbonate ions (72%) Carbon Dioxide Content of Blood As O 2 crosses into blood, CO 2 diffuses into alveoli Carbon dioxide in the blood PaCO 2 12

13 Exchange of Gases in Lung and Tissue Capillaries High CO 2 Drop in ph O 2 affinity for Hgb decreases Low CO 2 Increase in ph Oxygen affinity for Hgb increases Bohr Effect Fick Principle Movement and use of oxygen to perfuse tissues adequately Based on: Adequate oxygen available to RBCs through alveoli RBCs must circulate to tissue cells RBCs have to load in pulmonary capillaries and unload in tissues 13

14 Inadequate Blood Oxygenation Conditions affecting blood oxygenation Depressed respiratory drive Respiratory muscle paralysis Increased respiratory airway resistance Decreased compliance of lungs and thoracic wall Chest wall abnormalities Decreased surface area for gas exchange Increased respiratory membrane thickness Ventilation and perfusion mismatching Reduced capacity of blood to transport oxygen Hypoxia and Hypoxemia Hypoxia Inadequate oxygen at the cellular level Hypoxemia Deficiency of oxygen in arterial blood Anoxia A lack of oxygen Regulation of Respiration Voluntary control of respiration Nervous control of respiration Chemical control of respiration Control of respiration by other factors 14

15 Voluntary Control of Respiration Respiration can be consciously altered Hyperventilation can decrease PCO 2: Cerebral vascular constriction Paresthesia Dizziness Euphoria Breath holding Respiratory centers override Nervous Control of Respiration Phrenic and intercostal nerves Respiratory center in medulla Inspiratory center Spontaneous activity/fatigue Expiratory center Inactive in quiet respiration Forceful expiration Control of Respiratory Rhythm Vagal (Hering-Breuer) reflex Stretch receptors in lungs/chest inhibit respiration Limits inspiration Pneumotaxic center In pons Inhibits respiratory center Active in labored breathing Apneustic center Lower pons Stimulates inspiratory center 15

16 Regulation of Respiration Chemical Control of Respiration Determined by changes in: Carbon dioxide/hydrogen ion concentration Primary drive Medulla Oxygen Carotid arteries Aortic arch With chronic CO 2, elevation hypoxia becomes main respiratory drive Other Factors Regulating Respiration Body temperature Drugs Pain Emotion Sleep Activity 16

17 Control of Respiration Modified Forms of Respiration Cough Sneeze Sigh Hiccough Decreased vital capacity Older Patients Increased dead space Altered chest compliance Alveolar changes Altered control of respiration 17

18 Respiratory Pathophysiology Establishing and maintaining a clear airway is the most critical lifesaving maneuver performed It is always the first priority of patient care A common cause of poor ventilation is upper airway obstruction Foreign Body Airway Obstruction Airway obstruction conscious conscious patient Choking risk factors Partial airway obstruction Signs of inadequate air exchange Complete airway obstruction Airway obstruction unconscious unconscious patient Causes of airway obstruction Laryngeal Spasm and Edema Laryngeal spasm Spasmodic vocal cord closure May result from aggressive intubation technique Laryngeal edema Swelling of glottic and subglottic tissues may lead to laryngeal closure 18

19 Fractured Larynx Motor vehicle crashes common cause Edema may develop rapidly Rapid intervention may be required Pain Stridor Hoarseness Dysphonia Hemoptysis Subcutaneous emphysema Dysphagia Rare but serious Tracheal Trauma Often associated with injuries to: Esophagus Cervical spine CNS Abdomen Chest Aspiration by Inhalation Inhalation of food, foreign body, or fluid into airway Suspect in patients with decreased level of responsiveness May occlude airway and cause hypoventilation of distal lung tissue Associated risk factors Location of most aspirates Common aspirates 19

20 Pathophysiology of Aspiration Predisposing conditions Progression of an aspiration event Effects of pulmonary aspiration Effects of ph Effects on lung tissue Management Essential Parameters of Airway Evaluation Rate Adult 12-24/min 24/min Regularity Pattern Respiratory effort Work of breathing Recognition of Airway Problems Chest rise/fall Gasping Cyanosis Nasal flaring Pursed-lip breathing Chest muscle retraction Locations of retractions 20

21 Recognition of Airway Problems Auscultation with and without stethoscope Palpation of chest Other signs Recognition of Airway Problems History What makes it better or worse? Associated symptoms Any interventions at home Medication compliance Respiratory Patterns 21

22 Inadequate Ventilation Occurs when the body cannot: Compensate for increased oxygen demand Maintain normal oxygen/carbon dioxide balance Inadequate Ventilation Causes Infection Trauma Brain stem insult Noxious or hypoxic atmosphere Multiple symptoms Respiratory rate changes (up or down) Respiratory pattern changes Supplemental Oxygen Therapy Oxygen therapy Increases oxygen in pulmonary capillary blood Allows compensation without increased work of breathing Oxygen sources 22

23 Oxygen Cylinders Pressure Regulators Flowmeters 23

24 24%-44% 44% oxygen Flow rate: L/min Contraindicated if: Severe hypoxia Apnea Mouth breather Severe distress Well-tolerated Nasal Cannula 35%-60% oxygen Simple Face Mask Flow rate: L/min Carbon dioxide collects in mask if rate <6 L/min Partial Rebreather Mask Fill reservoir before use 35%-60% oxygen Flow rate: L/min Not for use with patients with poor respiratory effort, apnea 24

25 Nonrebreather Mask 80%-95% oxygen Flow rate: L/min or higher Fit firmly on face Reservoir never less than 2/3 full 24%-50% oxygen Venturi Mask Flow rate: L/min Precise regulation of FiO 2 Used for COPD patients Rescue Breathing Exhaled air 17% oxygen Limited by vital capacity of rescuer Potential for infectious disease spread Complications Hyperinflation Gastric distention 25

26 Position airway Pinch nostrils Take a normal breath Mouth-to to-mouth Seal over patient s s mouth Exhale over 1 second until chest rises Remove mouth for passive exhalation Mouth-to to-nose Ventilating through nose rather than mouth Indications Injuries to mouth, lower jaw Missing teeth or dentures Ventilating Infants and Children Cover both mouth and nose of infant Deliver each breath over 1 second Ventilate until chest rises Provide ventilations every sec 26

27 Mouth-to to-stoma Locate stoma site and expose Pocket mask to stoma preferred Alternative to mouth-to to- mouth ventilation One-way valve Limits infectious exposure Oxygen delivery Mouth-to to-mask More effective than mouth- to-mouth or BVM Mouth-to to-mask Technique 27

28 Bag-Mask Devices Self-refilling bag Valve allowing inflow of 15 L/min Non-pop pop-off off valve 15- and 22-mm fittings Delivers high-concentration O 2 Nonrebreathing valve Pressure to cricoid ring Cricoid Pressure Minimizes gastric distention Use with caution if C-spine C injury Complications Laryngeal trauma Esophageal rupture Pediatric Considerations Smaller bag-mask devices are needed Minimum volume ml > L/min of oxygen flow is necessary 28

29 Pediatric Considerations Bag-mask devices provide Ventilatory support in respiratory arrest BVM devices with fish-mouth mouth or leaf-flap flap operated outlet cannot be used to provide supplemental O 2 to spontaneously breathing infant or child Automatic Transport Ventilators (ATVs) Description Indications Contraindications Advantages Disadvantages Airway Management Basic to advanced techniques Rapid safe progression from least to most invasive procedures and devices 29

30 Head-Tilt/Chin Tilt/Chin-Lift Maneuver Opens airway Avoid if spinal injury suspected Jaw-Thrust without Head-Tilt If spinal injury suspected Stabilize head Provide in-line immobilization Suction Devices Fixed suction unit Portable suction unit 30

31 Soft catheters Suction Catheters Hard or rigid catheters Suction tubing without catheter Tracheobronchial suctioning Description Gastric Distention Management Noninvasive Gastric tubes Gastric Decompression Nasogastric Orogastric If nasal contraindicated 31

32 Complications of Gastric Decompression Uncomfortable May cause vomiting Tubes interfere with mask seals Tissue trauma from poor technique Tracheal placement Supragastric placement Gastric tube obstruction Nasopharyngeal (Nasal) Airway Maintains airway Semiconscious Temporary airway Nasopharyngeal (Nasal) Airway Sizing 32

33 Nasopharyngeal (Nasal) Airway Lubricate Largest nostril Disadvantages May enter esophagus Vomiting Obstruction Oropharyngeal (Oral) Airway Maintain airway No gag reflex Unconscious patient Measuring an Oral Airway 33

34 Oropharyngeal Airway Insertion Method 1 Method 2 Insertion Oropharyngeal Airway Advantages Complications Advanced Airway Procedures Endotracheal Laryngeal mask airway (LMA) Multilumen All require special training Follow local written guidelines/protocols 34

35 Endotracheal Intubation Indicated when: Unable to ventilate by other methods Patient cannot protect airway Prolonged artificial ventilation needed Endotracheal Intubation Video Clip: Endotracheal Intubation Endotracheal Intubation Advantages Isolates airway Facilitates ventilation Prevents gastric insufflation Route for medication administration NAVEL 35

36 Endotracheal Intubation Cuffed ET tube Children >8-10 years Uncuffed ET tube Straight Blades Curved Blades 36

37 Endotracheal Intubation ET tube with malleable stylet Recess stylet cm from distal end of ET tube Magill Forceps Nontrauma (Medical) Patient Patient supine Sniffing position to facilitate visualization 37

38 Endotracheal Intubation Lubricate tube Stethoscope, stylet, and suction available Ventilate with 100% oxygen for min Procedure for Intubation Position yourself at patient's head Inspect mouth for foreign material Suction if needed Open patient's mouth with fingers of right hand Grasp lower jaw with right hand Draw it forward and upward Remove any dentures Procedure for Intubation Hold laryngoscope in left hand Insert blade into right side of mouth Displace tongue to left Identify uvula Avoid pressure on lips or teeth 38

39 Procedure for Intubation If using a curved blade, advance tip of blade into vallecula Procedure for Intubation If using a straight blade, insert tip of blade under epiglottis Procedure for Intubation Expose the glottic opening by exerting upward traction on handle Do not pry Do not use teeth as a fulcrum 39

40 Procedure for Intubation Advance ET tube through right corner of mouth and, under direct vision, through the vocal cords Remove stylet (if used) Procedure for Intubation View of the vocal cords Procedure for Intubation ET tube passing through the vocal cords 40

41 Procedure for Intubation Pass end of cuffed tube past cords about cm (½ -11 inch) Observe depth markings on ET tube Inflate cuff Attach tube to mechanical airway device Begin ventilation and oxygenation Confirming Tube Placement Clinical method Auscultation Epigastrium Midaxillary Anterior chest line (Left and right sides) Confirmation devices Corrective measures Secure the ET Tube 41

42 Transillumination Technique (Lighted Stylet) High-intensity intensity light Little neck manipulation Thyroid and cricoid illuminated by light and ET tube advanced Digital Intubation Direct palpation of glottic structures to intubate trachea Patient entrapment Equipment failure Copious blood Intubation Potential complications Lacerated lips or tongue Dental trauma Lacerated pharyngeal or tracheal mucosa Tracheal rupture Vocal cord injury Vomiting and aspiration of stomach contents Vagal stimulation Bradycardia and hypotension Esophagus may be intubated 42

43 Nasotracheal Intubation Indications Spontaneous respirations when limited neck movement desired OD Asthma/anaphylaxis COPD Stroke Status epilepticus Blind procedure Nasotracheal Intubation Oxygenate patient Measure tube Lubricate Insert through largest nostril Nasotracheal Intubation Palpate larynx Listen for airflow over tube Verify placement Ventilate patient Secure tube 43

44 Nasotracheal Intubation Potential complications Epistaxis Vagal stimulation Injury to nasal septum or turbinates Retropharyngeal laceration Vocal cord injury Esophageal intubation Intubation with Spinal Precautions Requires minimum of two rescuers Procedure Sitting position method Intubation with Spinal Precautions Prone position method 44

45 Face-to to-face Intubation When positioning above head is not possible Open mouth with left hand Hold laryngoscope in right hand Face-to to-face Intubation Visualize cords from above mouth Pass tube with left hand Confirm placement Inflate cuff Ventilate Extubation Not often indicated in prehospital setting Suction oral cavity Deflate cuff Withdraw tube on exhalation Assess patient Oxygenate 45

46 Advantages of ET Intubation Provides complete airway management Helps prevent aspiration Positive-pressure ventilation can be given Large volumes of ventilations can be given Tracheal suctioning is possible Prevents gastric distention Provides a route for some drugs High concentration of oxygen can be given Pediatric Intubation Infant airway small with large tongue Epiglottis omega shaped and narrow Larynx more anterior and elevated Infant s s cords slope back to front Cricoid cartilage narrow Distance from carina to cords variable Diaphragm primary muscle for breathing Loose teeth may fall out End-Tidal CO 2 Detectors Verify ET placement Estimate alveolar ventilation 46

47 End-Tidal CO 2 Detectors EtCO mm Hg Waveform and ETCO2 value will be present if tracheal intubation High sensitivity High specificity Esophageal Detector Devices Bulb or syringe Easily fills if trachea is intubated Useful in situations where ETCO 2 is unreliable Oxygen saturation Pulse Oximetry Lower range 93%- 95% <90% SaO2 Decline in oxygenation is rapid 47

48 Pulse Oximetry The percentage of hemoglobin saturated with oxygen is denoted as SaO 2 SaO 2 depends on: PCO 2 ph Temperature Normal or altered hemoglobin Pulse Oximetry Lower range of normal for SaO 2 is 93%-95% 95% Upper range is 99%-100% Comparison of O 2 saturation and PO 2 90% saturation, PO 2 drops to 60 mm Hg 75% saturation, PO 2 drops to 40 mm Hg 50% saturation, PO 2 drops to 27 mm HG Pulse Oximetry Possible causes of false readings: Dyshemoglobinemia Excessive ambient light Patient movement Hypotension Hypothermia/vasoconstriction Vasoconstrictive drugs Nail polish Jaundice 48

49 Laryngeal Mask Airway (LMA) Indications If ET intubation is unsuccessful Limited access to patient Possible unstable neck injury Positioning for ET tube not possible Laryngeal Mask Airway Inserted through mouth into pharynx Advance until resistance Black line midline on upper lip Inflate cuff Placement confirmed Multilumen Airways Esophageal tracheal combitube (ETC) Pharyngeal tracheal lumen (PTL) Esophageal or tracheal placement Advantages 49

50 Multilumen Airways Guide device into esophagus or trachea Inflate distal and pharyngeal balloons Ventilate through esophageal lumen Confirm placement Multilumen Airways Common disadvantages Patient must be unresponsive without a gag reflex Airway must be removed when patient becomes responsive or agitated Tracheal suctioning is not possible when tube is in the esophagus Common contraindications Patient under 5 ft tall/<14 y/o Caustic ingestion Esophageal trauma or disease Presence of gag reflex Pharmacological Adjuncts Sedation Tranquilizers Barbiturates Benzodiazepines Narcotics 50

51 Pharmacological Adjuncts Paralytic agents used for intubation Depolarizing agents Can lead to fasciculations Succinylcholine (Anectine) Nondepolarizing agents Vecuronium (Norcuron) Pancuronium (Pavulon) Rapid Sequence Intubation Indications Emergency intubation needed Full stomach Intubation likely to be successful If intubation fails, ventilation possible Six Ps of RSI Preparation Preoxygenation Pretreatment Paralysis (with induction) Placement of the tube Postintubation management 51

52 Translaryngeal Cannula Ventilation Description Indications Advantages Disadvantages Potential complications Translaryngeal Cannula Ventilation Patient who can t t be intubated or ventilated If airway obstructed Edema Fractured larynx Severe hemorrhage High-volume/high volume/high-pressure oxygenation Does not protect airway Does not efficiently eliminate CO 2 Short-term term measure Translaryngeal Cannula Ventilation Stabilize larynx and identify cricothyroid membrane 52

53 Translaryngeal Cannula Ventilation Insert needle of syringe downward through membrane toward carina Translaryngeal Cannula Ventilation Apply negative pressure to syringe Air in syringe indicates needle is in trachea Translaryngeal Cannula Ventilation Remove needle/syringe, stabilize catheter Connect oxygen tubing to oxygen regulator Provide for a release valve 53

54 Description Cricothyrotomy Relative indications Potential complications Contraindications Needle Cricothyrotomy Insert large-bore catheter through cricothyroid membrane Needle Cricothyrotomy Slide catheter off stylet into larynx 54

55 Surgical Cricothyrotomy Make incision through cricothyroid membrane Surgical Cricothyrotomy Open hole by twisting handle of scalpel in it Surgical Cricothyrotomy Open hole with a clamp 55

56 Surgical Cricothyrotomy Insert ET tube Retrograde Intubation Less invasive than cricothyrotomy Not recommended for apneic patients Retrograde Intubation Puncture cricothyroid membrane Pass guide wire Advance ET tube over guide wire Withdraw wire 56

57 Conclusion A thorough understanding of the respiratory system and mastery of airway management and ventilation are important aspects of prehospital emergency care. Questions? 57