Chapter 6 Respiratory/Airway Emergencies

NLC CCT Program Introduction

 Most critical and difficult skill for prehospital providers  BLS skills are basis before ALS skills:  Manual airway maneuvers  Head-tilt chin lift  Jaw-thrust  Basic mechanical airways  Nasopharyngeal  Oropharyngeal  Advanced airway management  Naso/orotracheal intubation  Intubation of the trauma/medical patient  Surgical airways Lil Airway Review Lil Airway Review

 Important structures of upper airway  Nose  Structure made of bone and cartilage that warms and humidifies air on inspiration. Where 1st cranial nerve originates. (Olfactory)  Mouth Begins at lips and ends at the oropharynx. Houses teeth, salivary glands and the tongue; which is the most common cause of airway obstruction. Lil Airway Review Continued

 Important structures of upper airway  Pharynx  U-shaped tube. Made of 3 parts: naso/oro/hypopharynx.  9th CN (glossopharyngeal) is responsible for sensory input from this area.  Larynx Houses several structures as in thyroid cartilage, epiglottis and vallecula. 10th CN (vagus) is dominate for sensory input, stimulation can cause alterations in HR and BP Lil Airway Review Lil Airway Review Continued

 Important structures of lower airway  Trachea  Made of approximately 20 C-shaped rings anteriorly.  The rings help to maintain airway patency.  Lungs  Inferior division of trachea divides into right and left mainstem bronchi, just past the carina.  Functional unit of lungs are the alveoli.  Pulmonary artery contains blood high in CO2 Considerations for Infants and Children Considerations for Infants and Children

 Airway Anatomy in Infants and Children  Chest wall is pliable.  Increased reliance on diaphragm.  Lungs are easily overinflated in artificial ventilation.  Epiglottis is larger and more floppy  Cricothyroid membrane is smaller  Limited oxygen reserves.  High metabolic rate and oxygen needs.  Hypoxia is the most common cause of cardiac arrest. Blood Supply to the Lungs

 Blood supply to lung  Venous blood flows into pulmonary veins  Deoxygenated blood mixes with oxygenated blood in pulmonary veins  Pulmonary arteries  Deoxygenated blood  Low pressure system  Alveoli  Must have constant blood flow  PCO2: 40 mm Hg, PO2: 100 mm Hg  Capillary  PCO2: 45 mm Hg, PO2: 40 mm Hg

V/Q Ratio Ventilation Perfusion (V/Q) Mismatch

 V/Q ratio  Ratio of about 0.8 in healthy individual  Ventilation and perfusion are imperfect due to:  Gravity  Alterations in pulmonary/alveolar pressures  Obstruction  Compliance  Increased perfusion in lower lobes (dependent)  Increased ventilation in higher lobes (nondependent) Ventilation Perfusion (V/Q) Mismatch

 Factors affecting V/Q ratio  Ratio decreases when ventilation is impaired, perfusion remains normal  Ratio increases when perfusion is impaired, ventilation remains normal Ventilation Perfusion (V/Q) Mismatch

 Types of V/Q mismatch  Low V/Q ratio  Perfusion exceeds ventilation  pneumonia  High V/Q ratio  Ventilation exceeds perfusion  PE  Silent unit  Decrease in ventilation/perfusion  pneumothorax

Physiology of Respiratory System

 Hemoglobin  Binding site for O2  Transports O2 to tissues  Oxyhemoglobin dissociation curve  Relationship between SaO2 and PaO2  O2 binding to hemoglobin is PaO2  O2 dissociation(unloading) from hemoglobin is determined by tissues demand for O2

Physiology of Respiratory System

 Gas exchange  Due to pressure gradients  PaO2 drives O2 to hemoglobin  Dysfunctional hemoglobin  Many substances can bind to hemoglobin causing dysfunction  Example: CO has 240 times affinity for hemoglobin than O2 Physiology of Respiratory System

 Dynamics of breathing  Compliance  Ease of the lungs and thorax expand  Resistance  Force required to move gas/fluid through capillary bed  Pressure Gradient  Allow majority of gas to move in and out of lungs

Physiology of Respiratory System

 Breathing stimulus  Normal is to eliminate CO2  Co2 increases causes increase of H+ causing acidosis  Centers are located in brain stem  DRG  Impulses to diaphragm  VRG  Expiration and respiratory patterns

Volumes/Capacities of Respiratory System

 Total lung capacity (TLC)  Adult male 5-6 L  Adult female 4-5L

 Tidal Volume (Vt)  Amount of air moved with 1 normal breath  Minute Volume  Air breathed in 1 min normal is 5-10 L  RR (x) tidal volume=500 ml (x) 12

Volumes/Capacities of Respiratory System

 Inspiratory Reserve Volume (IRV)  Amount of air that can be inhaled after normal inhalation  Expiratory Reserve Volume (ERV)  Amount of air that can be exhaled after normal exhalation  Inspiratory Capacity

 Sum of IRV and Vt

Volumes/Capacities of Respiratory System

 Vital Capacity (Vc)  Total amount of air that can be exhaled after maximum inspiration  Called pulmonary reserve  Normal is 60/70 mL/kg  Decreased with age  Indication for mechanical ventilation when reached 10/15 mL/kg

Volumes/Capacities of Respiratory System

 Residual Volume (RV)  Air remaining after maximum exhalation  Functional Residual Capacity (FRC)  RV (+) ERV  Allows for gas exchange in between breaths  Positive end-expiratory pressure (PEEP)  Increases FRC

 Anatomic dead space (VD)  Air in upper airway not utilized in gas exchange  Normally 2 mL/kg

Volumes/Capacities of Respiratory System Obstructive Disease States

 Obstructive diseases  Difficulty in moving air out of lungs  COPD, Cystic Fibrosis, Asthma  Restrictive diseases  Difficulty in moving air into lungs  Loss of either chest or lung compliance or both  Idiopathic pulmonary fibrosis, occupational lung disease, pneumonia

Hypoxic Forms

 Hypoxic hypoxia

 Insufficient O2 in blood and tissues  Hypovolemia, airway obstruction, CAD, decrease in CO  Anemic hypoxia  Due to decrease or dysfunctional hemoglobin  Anemia, hemorrhage, inhalation of chemicals  Stagnant hypoxia

 Insufficient O2 in tissue due to decreased circulation/cardiac output  Temps, posture, restriction, hyperventilation, clots, CVA  Histotoxic hypoxia

 Decrease in ability for cells to use O2 because lack of specific enzymes  Cyanide, strychnine, late CO poisoning (red)

Assessing Breath Sounds Assessing Breath Sounds

 Tracheal Breath Sounds (bronchial sounds)  Inspiration/Expiration are both loud  In bronchial sounds inspiration is shorter  Place scope over trachea or sternum  Vesicular Breath Sounds  Softer, muffled sounds  Inspiration auscultated better than exhalation  Bronchovesicular Breath Sounds  Mix of above breath sounds  Heard over airways and alveoli

Assessing Breath Sounds

 Adventitious Breath Sounds  Wheezing  Ronchi  Crackles (rales)  Stridor  Pleural friction rub Assessing Breath Sounds

8

#1 and #8 Invasive airway auscultation Assessing Breath Sounds

 Rate  Eupnea  Normal rate 12-20  Tachypnea  Fast, <20

 Decreased (VA)  Bradypnea  Slow rate >10  Apnea  Absent or extremely slow, possibly at intervals

Assessing Breath Sounds

 Pattern (rhythm)  Many different forms  Cheyne-Stokes  Cluster  Biot’s (ataxic)  Kussmaul’s  Apneustic  Central Neurogenic  Agonal Assessing Breath Sounds

 Depth (quality)  Hyperpnea  Deeper than normal  Alkalosis  Depth (quality)  Hypopnea  Shallow breathing  Acidosis

Transport Preparation

 Prior to transport  ABC’s  Stability of airway patency  Chest symmetry  Assess dressings (if any)  Secure tubes  Assess drainage tubes (chest tube)  ABG’s  Capnography (waveform)

Abnormalities

 Respiratory insufficiency  Respiratory system unable to meet body’s metabolic demands  Respiratory depression  Respiratory failure  Respiratory system unable to meet body’s metabolic demands

 O2 or ventilatory faliure

Airway Management

 Positioning  Sniffing  Head tilt-chin lift  Tongue-jaw lift  Jaw thrust Airway Management

 Airway Adjuncts  O2 Administration  NPA  NC  OPA  NRM

 Suctioning  Supplemental O2  Yankauer  Rescue mask  French  BVM

Advanced Airway Management

 Indications for  Failure to maintain patency  Failure in oxygenation or ventilation  Decreased LOC  Absent gag reflex  Low GCS  Respiratory failure/arrest  Cardiac arrest Advanced Airway Management

 Evaluate airway Advanced Airway Management

 Cormack and Lehane grading system  Grades view glottic anatomy under direct laryngoscopy Advanced Airway Management

 Intubation adjuncts  Assist with endotracheal intubation  Useful when glottic opening difficult to visualize  Bougie  BURP maneuver  ELM  Cricoid pressure Advanced Airway Management

 Orotracheal Intubation  Airway control  Coma, cardiac/respiratory arrest, burns, trauma  Ventilatory Support

Advanced Airway Management

 Nasotracheal Intubation  Airway control  Awake with impending respiratory failure  Have gag reflex  Breathing but cannot open mouth  Contraindications  Apneic or bradypnea  Cannot pass tube through nostril  Severe facial, nasal, basilar skull fractures

Advanced Airway Management Advanced Airway Management

 Digital intubation  Unconscious, apneic, no gag reflex, obese, no neck  Fingers used to guide tube

Advanced Airway Management

 Retrograde intubation  Unsuccessful intubation attempts Advanced Airway Management

 Face-to-face  Useful in MVC and tight spaces Advanced Airway Management

 Transillumination  Trapped in vehicle  Sitting in chair  Like Face-to-Face, but with a light

Advanced Airway Management

 LMA  Rescue airway  Used in OR  Some systems utilize  May be BLS skill

Advanced Airway Management

 Complications of Intubation  Use D.O.P.E pneumonic and capnography to correct  Extubate if needed, reintubate  Use BLS airway  Surgical airway

Surgical Airways

 Used after failed orotracheal intubation  Indications  Inability to ventilate or intubate a patient by oral or nasal routes  Contraindications  Ability to ventilate or intubate a patient by oral or nasal routes  Inability to identify anatomical landmarks Surgical Airways

 Needle Cricothyrotomy  Used only temporary until surgical cricothyrotomy or other definitive airway can be secured  Allows oxygenation but little ventilation  Expect hypercarbia Surgical Airways Surgical Airways

 Surgical Cricothyrotomy  Failed intubation attempts  Obstruction of airway  Last option  Provides better oxygenation and ventilation compared to needle cricothyrotomy  Contraindicated for those <8 y/o Surgical Airways Rapid Sequence Intubation (RSI)

 Involves the rapid sedation and paralyzing of a patient with the goal of increasing the likelihood of successful orotracheal intubation  Indications  Impending respiratory failure secondary to pulmonary disease  Acute loss or potential loss of airway  Decreased mentation, low GCS  Not normally needed in cardiac arrest Rapid Sequence Intubation (RSI)

 Steps  Preparation  Induction  Premedication  Neuromuscular blockade  Maintenance therapy Rapid Sequence Intubation (RSI)

 Sedation/Induction  Sedation induces unconsciousness  Patient cannot appreciate, respond to, or recall event  Many agents used in emergency medicine  Agent depends on patient presentation/complaint  Atropine may/may not be part of prep depending on region SOP Sedative/Induction Medications Thiopental Sodium (Pentothal)

 Short-acting barbiturate  CNS depressant  Onset of action: 10–20 seconds  Duration of effect: 5–10 minutes  Dose: 2–5 mg/kg IV  Significant hemodynamic effects  Worsens hypotension  Decreases ICP  Ideal for head injury Etomidate (Amidate)

 Short-acting, nonbarbiturate, hypnotic agent  Attractive safety profile  Onset of action: 10–20 seconds  Duration of effect: 3–5 minutes  Dose: 0.2–0.3 mg/kg IV over 15–30 seconds  Too low of a dose may cause trismus

Propofol (Diprivan)

 Good for long-term, rapid induction  May cause profound hypotension  Onset of action: 10–20 seconds  Duration of effect: 10–15 minutes  Dose: 1–3 mg/kg Fentanyl (Sublimaze)

 Short-acting opiate  Synthetic opiate  Chemically unrelated to morphine  Widely used in anesthesia  Onset of action: Immediate  Duration of action: 30–60 minutes  Dose: 2–10 mcg/kg IV Morphine

 Less potent and less effective than fentanyl  Hemodynamic properties make it unattractive  Onset of action: 3–5 minutes  Duration: 2–7 hours  Dose: 0.1–0.2 mg/kg IV Ketamine (Ketalar)

 Dissociative drug  Used in pediatric anesthesia  Patient appears awake, is deeply anesthetized  Causes catecholamine release  Increases sympathetic nervous system tone  Increases heart rate, cardiac output , blood pressure  Onset of action: 45–60 seconds  Duration of action: 10–20 minutes  Dose: 1–4 mg/kg  Ideal for asthmatics and hemodynamically unstable patients Midazolam (Versed)

 Popular induction agent for prehospital RSI  Potent amnesic effects  Two to four times more potent than diazepam  Onset of action: 1–2 minutes  Duration of action: 30–60 minutes  Dose: 0.1–0.3 mg/kg IV At high doses, may promote cardiovascular collapse Diazepam (Valium)

 Features similar to midazolam  Not water soluble, less potent  Greater potential for hypotension  Onset of action: 2–4 minutes  Duration of effect: 30–90 minutes  Dose: 0.25–0.4 mg/kg IV Lorazepam (Ativan)

 Long-acting benzodiazepine  Useful for long-term sedation after intubation  Onset of action: 1–5 minutes  Duration of action: 1–2 hours  Dose: 50 mcg/kg IV Potential Premedications

 Premedication serve to:  Blunt physiologic responses to neuromuscular blockers  Blunt physiologic responses to laryngoscopy and intubation  Decreases autonomic nervous system stimulation Lidocaine (Xylocaine)

 Thought to prevent rise in ICP  Patients with possible head injury  Patients with CNS pathology  Suppresses cough reflex and increases in airway resistance  Dysrhythmia control  Dose: 1.0–1.5 mg/kg IV Can be sprayed directly onto vocal cords when spasm exists Atropine

 May reduce laryngoscope-induced bradycardia in children  Possible indications in patients 10 years old  Will also help to dry oral secretions  Anticholinergic  Administer 2 minutes before intubation attempts  Dose: 0.01 mg/kg IV to a maximum of 3.0 mg  Used only if in SOP Neuromuscular Blocking Agents Neuromuscular Blocking Agents

 Facilitate endotracheal intubation  Paralyze skeletal muscle  Do not affect level of consciousness  Do not affect pain sensation  Specific agents  Succinylcholine (Anectiune)  Pancuronium (Pavulon)  Vecuronium (Norcuron)  Atracurium (Tracrium)  Rocuronium (Zemuron) Depolarizing Blocking Agents

 Succinylcholine (Anectine) is only depolarizing neuromuscular blocking agent used in prehospital care  Rapid onset and short duration  Ideal for RSI  Depolarization of cell membrane, causing muscle twitching (fasciculations) Phase 1  Unresponsive to stimulation, flaccid paralysis, Phase 2 Depolarizing Blocking Agents Nondepolarizing Blocking Agents

 Several used in prehospital  Act by blocking the binding site of ACH, blocking stimulus  Tend to have long durations of action  Used for long-term paralysis Succinylcholine (Anectine)

 Most widely used neuromuscular blocking agent  Depolarizing agent  Causes fasciculations before paralysis  Can increase ICP  Use of defasciculating dose of neuromuscular blocking agent may be suggested  Elevates serum potassium levels  Onset of action: 30–60 seconds  Duration of action: 5 minutes  Dose: 1-2mg/kg IVP Vecuronium (Norcuron)

 Nondepolarizing agent  Does not cause fasciculations  Commonly used as a defasciculating agent before administration of Anectine  0.01 mg/kg IV  Generally considered a second-line paralytic if Anectine is contraindicated  Onset of action: 2–3 minutes  Duration of action: 60-75 minutes  Dose: 0.15 mg/kg IV Pancuronium (Pavulon)

 Nondepolarizing agent  Does not cause fasciculations  Advantage of rapid onset offset by long duration of action  Can be disadvantageous in instances of failed intubation  Onset of action: 1-2minutes  Duration of action: 45-60minutes  Dose: 0.1 mg/kg IV Rocuronium (Zemuron)

 Nondepolarizing agent  Does not cause fasciculations  Short onset of action makes it good choice for patients with contraindications to Anectine  Onset of action:< 2 minutes  Duration of action: 30–60 minutes  Dose: 0.6 mg/kg IV Transport Ventilator

 Designed for convenience and easy use  Lightweight  Durable  Run off portable oxygen supply  Control of:  Ventilatory rate  Tidal volume  Ventilation mode  Pop-off valve to control pressure  Hindrance in cases where high airway pressures desirable  ARDS  Cardiogenic pulmonary edema Negative Pressure Ventilators

 Used in 1950’s for Polio epidemic  Work similar to normal breathing pattern  New forms of iron lung may be used in long term care

Positive Pressure Ventilators

 Tidal volume administered at increase pressures  Types are utilized for which variable ends inspiratory phase.  Pressure Ventilators  End delivery of tidal volume based on a set pressure  Volume Ventilators  End delivery of tidal volume based on a set volume  Flow-cycled Ventilators  End inspiration based on a set flow rate  Time-cycled Ventilators  End inspiration based on a set time

Ventilator Modes Assist/Control

 Provides full tidal volume at preset rate  Patient can initiate breath on own, ventilator will assist with full tidal volume  Provides near-complete rest to ventilatory muscles  Can be used in patients who are:  Conscious  Sedated  Paralyzed Synchronized Intermittent Mandatory Ventilation (SIMV)

 Ventilator delivers preset tidal volume at predetermined rate  If patient initiates own breath, ventilator will not provide preset breath  Ventilator does not support patient breath with full tidal volume  Often used to “wean” patients off ventilator  Respiratory fatigue/failure can develop if rate set too low Pressure Support

 Ventilator assists spontaneous breaths to predetermined peak pressure  Overcomes resistance and improves compliance  Cannot be used in patients who are comatose, heavily sedated, or paralyzed  Respiratory fatigue/failure can occur if pressure support set too low Pressure-Regulated Volume Control (PRVC)

 Pressure and respiratory rate predetermined  Ventilation delivered until predetermined pressure reached  Adjusts pressure from breath to breath  Monitors volumes and adjusts pressure to achieve set volume and pressure Positive End-Expiratory Pressure

 Set to stop exhalation at a set pressure

 Application of 2.5–20 cm H2O of pressure to end of expiration  Increases FRC, keeps alveoli open  Prevents atelectasis  Can result in:  Barotrauma  Air trapping  Increased intrathoracic pressure Ventilator Parameters

 Sensitivity (trigger)  Assist mode  Triggered when patient initiates a breath  Inspiratory effort, measured as negative pressure, required to initiate a breath

 Common settings  1–2 cm H20 Ventilator Parameters

 Minute Ventilation  Vmin (mL/min)  VT (mL)  Respiratory Rate (minute)  Normally 6–10 lpm in adults  Tidal Volume  Volume of each breath  VT (ml)  VA  VD  VA  alveolar air  VD  dead space air  Commonly between 5–15 ml/kg ideal body weight  Respiratory Rate  8–12 breaths per minute  20 breaths per minute  hyperventilation

Ventilator Parameters

 Inspiration/Expiration (I/E) Ratio  Normal setting 1:2  1:4, 1:5 commonly used in cases of restrictive airway disease to prevent air stacking  Flow Rate  40–80 lpm commonly used  Patients with obstructive lung disease require higher flow rates

Ventilator Parameters

 Inspired Oxygen Concentration (FiO2)  Initially set at 1.0 (100 percent)  Titrated down based on blood gas values

 Lowest FiO2 used to avoid oxygen toxicity

 With known blood gas values, can predict needed FIO2 settings  Sigh  normal respiratory function  Helps prevent atelectasis  1.5–2.0 times the normal tidal volume, 10–15 times per hour

Alarms High-Pressure

 Usually set to activate when pressure exceeds 10–20 cm H20 over patient’s peak inspiratory pressure  Triggers include:  Increased airway resistance  Accumulation of secretions  Kinking of vent circuit tubing  Bronchospasm  Patient coughing  Decreased lung compliance  ARDS  Pneumothorax  Atelectasis  Pulmonary edema  Pneumonia Low-Pressure

 Usually set to activate if tidal volume falls 5–10 cm

H2O below set volume  Triggers include:  Disconnected vent circuit  ET cuff leak Low FiO2

 Alarm sounds if FiO2 decreases to predetermined level  Triggers include:  Disconnected oxygen tubing  Depletion of oxygen