Objectives. Respiratory Failure : Challenging Cases in Mechanical Ventilation. EM Knows Respiratory Failure!

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Respiratory Failure : Challenging Cases in Mechanical Ventilation Peter DeBlieux, MD, FAAEM, FACEP LSUHSC University Hospital Pulmonary and Critical Care Medicine Emergency Medicine pdebli@lsuhsc.

1 Respiratory Failure : Challenging Cases in Mechanical Ventilation Peter DeBlieux, MD, FAAEM, FACEP LSUHSC University Hospital Pulmonary and Critical Care Medicine Emergency Medicine pdebli@lsuhsc.edu Objectives At the end of this presentation participants should be able to: Review different ventilator settings for specific patient populations Describe the relationship between the components of the blood gas and the effect of ventilator changes Discuss approaches to reducing patient injury when utilizing mechanical ventilation EM Knows Respiratory Failure! Indications for intubation: Airway protection Respiratory failure Expected clinical course 1

2 Respiratory Failure The most common indication for institution of mechanical ventilation is patient fatigue. The inability of the patient to handle the work of breathing. Signs and Symptoms of Respiratory Failure Not one single indicator for respiratory failure Consider patient s cardiopulmonary reserve Hypoxemia results in sympathetic nervous system activation. Acute hypercapnia causes central nervous system depression by lowering cerebrospinal fluid ph. Signs of Impending Respiratory Failure Respiratory rate > 35 breaths per minute PaO 2 < 55 mmhg on FiO 2. > 50% Hemodynamic instability 2

3 Signs of Impending Respiratory Failure Paradoxical respiratory efforts Mental status deterioration Rising PCO 2 > 55 mmhg with respiratory acidosis Requirements for Noninvasive Mechanical Ventilation Experienced support staff respiratory therapist, nursing and physician education is essential Variety of facemask sizes and types to assure comfort, air seal A cooperative patient who is willing to participate in their care Contraindications to Noninvasive Mechanical Ventilation Rapid deterioration Decreased mental status Aspiration risks/aerophagia Facial instability/pressure necrosis Need for a definitive airway/ventilation Excess secretions Coronary ischemia 3

Predictors of Failure in Noninvasive Mechanical Ventilation MC Trial 354 pts Higher severity of illness score Older age ARDS Pneumonia Failure to improve in one hour Wysocki M, Antonelli M, Eur Resp

4 Predictors of Failure in Noninvasive Mechanical Ventilation MC Trial 354 pts Higher severity of illness score Older age ARDS Pneumonia Failure to improve in one hour Wysocki M, Antonelli M, Eur Resp J 2001 Jul;18(1): Pearls For NPPV Start with low pressures 8/3 or only CPAP Have patients hold mask and apply Constant reassurance Tread lightly with sedation Pediatric patients-consider it Correct hypoxia with appropriate oxygenless concern over toxicity acutely Consider intubation if not improved in 1 hour 4

5 Case One A 69 yo female with a long standing history of emphysema presents complaining of SOB. She has received aerosol therapy, oxygen, Solumedrol and noninvasive mechanical ventilation without improvement. Her respiratory rate increases from 34 to 40 bpm and she is removing the BIPAP mask from her face.abg 7.20/66/60 FiO2 40% Respiratory Failure Mode Respiratory rate Tidal volume cc/kg IBW PEEP cm H2O FIO2 % Peak flow L/min Respiratory Failure Mode Assist Control Respiratory rate Tidal volume 7-8 cc/kg IBW PEEP 5 cm H2O FIO2 100% Peak flow 60 L/min 5

6 ABG and Ventilators ABG plays no role in deciding the need for intubation Oxygenation is primarily a function of FiO 2 and PEEP CO 2 is a primary function of respiratory rate and secondarily tidal volume Oxygenation Start with an FiO2 of 100% Increase PEEP in increments of 2-3 cm H 2 O every min until oxygenation goals are achieved Follow plateau pressures and consider decreasing tidal volume as plateau pressures increase > 30 cm H 2 O Ventilation Goal, maintaining ph in the range Often, patients have an altered PCO 2 due to compensation for underlying metabolic problems Changes in either respiratory rate or tidal volume typically alter minute ventilation and affect PCO 2 6

7 Ventilation Respiratory rate has a greater effect on PCO 2 and ph than tidal volume Increasing the respiratory rate or the tidal volume will cause a decrease in PCO 2 and classically raise the ph Decreasing the respiratory rate or the tidal volume will cause an increase in PCO 2 and classically lower the ph Modes of Mechanical Ventilation CPAP Control Assist Control SIMV Pressure Support SIMV with Pressure Support Mechanical Ventilation Lung Volume Airway Pressure Peak Airway Pressure Time 7

8 CPAP Continuous positive airway pressure PEEP May be used in conjunction with pressure support Requires a spontaneously breathing patient CPAP Mode Lung Volume Airway Pressure Time 8

9 CPAP Consider in the following cases: Airway protection cases without respiratory compromise Weaning trial candidates-preparing to extubate Control Volume cycled mode Every breath is machine initiated and dictated No utility outside of the operating room Control Mode Lung Volume Airway Pressure M M M M Time 9

10 Assist Control Preset rate and tidal volume For each additional triggered attempt the ventilator will deliver a standard tidal volume breath Initial mode of choice for respiratory failure Assist Control Mode Lung Volume Airway Pressure M M P P Time SIMV Synchronized intermittent mandatory ventilation Preset rate and tidal volume synchronized to the patient s efforts For each additional triggered attempt the ventilator will deliver a variable tidal volume breath dictated by patient effort 10

11 SIMV Mode Lung Volume Airway Pressure M M P P Time SIMV Mode Lung Volume Airway Pressure M M Yellow areas signifies work of breathing P P Time Pressure Support Preset pressure boost Delivery of a variable tidal volume based on lung, chest wall, ventilator system compliance and patient effort Requires a spontaneously breathing patient 11

12 SIMV with Pressure Support Offers the benefits of pressure support with the security of a back-up rate Pressure support is delivered each time the patient generates a negative inspiratory effort SIMV + PSV Lung Volume Airway Pressure M M P P Time CPAP + PSV Lung Volume Airway Pressure P P P P Time 12

13 Work of Breathing The work of breathing can be significant in CPAP, SIMV and Pressure Support modes of ventilation. Avoid these modes if your patient has respiratory fatigue. Case Two A 23 yo female with a history of asthma presents with acute onset of shortness of breath. Her RR is 34 and she has an initial PEFR of 100. Despite continuous aerosol therapy, steroids, oxygen, and magnesium. Her clinical exam and PEFR is unchanged. She is now anxious and confused. Reactive Airways Mode Respiratory rate Tidal volume cc/kg IBW PEEP cm H2O FIO2 % Peak flow L/min 13

14 Reactive Airways Mode Assist Control Respiratory rate 8-12 bpm Tidal volume 6 cc/kg IBW PEEP 5cm H2O FIO2 100% Peak flow L/min What are the dangers associated with reactive airways disease and mechanical ventilation? Respiratory Cycle Airflow In Airflow out End exhalation No Intrinsic PEEP 14

15 Intrinsic PEEP Measured by occluding the exhalation port at end exhalation Airway pressures equalize throughout system Respiratory Cycle Airflow In * Signifies trapped volume before and after respiratory cycle Airflow out * * End exhalation with Intrinsic PEEP Intrinsic PEEP Results from: early airway closure insufficient exhalation time Rapid respiratory rate 15

16 Intrinsic PEEP Leads to air trapping with progressive hyperinflation of the lung Causes a high work of breathing, fatigue May cause reduced venous return and hypotension Work of breathing Machine initiated breath Patient initiated breath W.O.B. Respiratory Rate RR = 20 (resp cycle 3 seconds) I E RR = 12 (resp cycle 5 seconds I E 16

17 Peak Flow The speed that a tidal volume is delivered Typically preset at 60 L/min Increased from L/min in those patients with reactive airways disease May increase PIP but not plateau pressures Reactive Airways Methods to reduce Intrinsic PEEP and increase expiratory time-emptying #1 - reduce respiratory rate 8-12 bpm #2 reduce tidal volume 6 cc/kg IBW #3 increase peak flow l/min Case Three A 55 yo female presents with multilobar pneumonia extensively involving both lung fields. She is not maintaining oxygen saturations on 100% NRB and she begins to tire. 17

18 What are the concerns mechanically ventilating patients with multilobar infiltrates, edema and extensive disease patterns? Multilobar Disease Mode Respiratory rate Tidal volume cc/kg IBW PEEP cm H2O FIO2 % Peak flow L/min 18

19 Multilobar Disease Mode Assist Control Respiratory rate bpm Tidal volume 6 cc/kg IBW PEEP 5cm H2O FIO2 100% Peak flow 60L/min Multilobar Disease Acute Lung Injury Diffuse Lung Injury ARDS must exclude CHF Multilobar Disease Management Concerns Oxygenation High pressures High relative volumes Ventilation 19

20 PEEP Positive end expiratory pressure Increases residual volumes and total lung volumes 5 cm H 2 O is considered physiologic by some and unnecessary by others High levels may limit venous return and injure the lung Alveolar Distention PEEP 6 cc/kg cc/kg Good U g l y Bad Increasing Lung Volume / Plateau Pressure Good lung can be recruited and then over distended creating lung injury Case Three Cont d Her initial settings are FIO2 100%, AC, rate of 20, Tidal volume of 6 cc/ kg and PEEP of 5cmH2O. Her ABG after being on the ventilator for 30 minutes is ph 7.38 PCO2 36 PaO2 50. What are the appropriate changes? 20

21 Hypoxia Mode Respiratory rate Tidal volume cc/kg IBW PEEP cm H2O FIO2 % Peak flow L/min Hypoxia Mode Assist Control Respiratory rate 20 bpm Tidal volume 6cc/kg IBW PEEP 7-8cm H2O FIO2 100% Peak flow 60L/min 21

22 Hypoxia Adjustments To affect oxygenation, adjust: FiO2-first PEEP-second only if FiO2 100% Progressive increases in PEEPyield increases in: Pressure Volume Hypoxia Goals Maintain oxygen saturations in the 88-92% range Caution in cardiac/neuro disease Maintain plateau pressures less than 30 cm H 2 O May require lowering tidal volumes Case Four A 50 yo male with a history of COPD and obesity hypoventilation has been intubated due to confusion and apnea. His ABG on a 100% non rebreather mask is ph 7.20 PCO2 90 PaO2 90. He weighs 250 KG and is five foot five inches tall. His vent settings should be: 22

23 OSA at Age 1 Hypercapnea Mode Respiratory rate Tidal volume cc/kg IBW PEEP cm H2O FIO2 % Peak flow L/min Hypercapnea Mode Assist Control Respiratory rate Tidal volume 7-8cc/kg IBW PEEP 5cm H2O FIO2 100% Peak flow 60L/min 23

24 Hypercapnea Adjustments To affect ventilation, adjust: Respiratory rate-primarily Tidal volume-secondarily Progressive increases in respiratory rate will reduce the I:E ratio Caution in reactive airways Hypercapnea Goals ph range Acutely, for every 10 change in PCO2 there will be a change of ph of.08 Chronic hypercapnea will have relatively normal ph values >7.30 Case Five A 30 yo male has just been placed on mechanical ventilation following a severe MVC. He sustained multiple rib fractures that created a flail segment and awaits CT scan of his head and abdomen. The mechanical ventilator begins to alarm and the nurse informs you his BP is 60/palp!! 24

25 What To Do? Avoid Bad Parenting Trouble Shooting Disconnect the patient from the ventilator and bag the patient with 100% oxygen Confirm ETT placement-airway Auscultate the lungs-breathing Consider other causes of circulatory compromise-circulation Keep needle and tube thoracostomy kit handy 25

26 Common Problems Endotracheal tube- extubation, plug, mainstem, kink Tension pneumothorax Dynamic hyperinflation- auto peep Agitation diagnosis of exclusion Equipment failure - ventilator, suction, oxygen delivery, nebulizer Pressure Manometer Peak Inspiratory Pressure (PIP)- the highest inflection point reached during delivery of a breath Dictated by system and patient compliance No correlation of PIP with risk of lung injury Pressure Manometer Plateau Pressure - if an inspiratory pause is placed at the end of inspiration, the needle comes to rest at a point- the plateau pressure Reflects the pressure witnessed by the alveolus and correlates with the risk of lung injury > 30 cm H 2 O 26

Pressures High Volumes High FIO2 Rapid Alveolar Opening Alveolar Injury

27 Plateau Pressure Lung Volume Airway Pressure Peak Airway Pressure * * + Plateau Pressure + Time Ventilator Induced Lung Injury - VILI High Pressures High Volumes High FIO2 Rapid Alveolar Opening Alveolar Injury Am J Respir Crit Care Med 1998;158: Ventilator Induced Lung Injury 27

28 VILI Pulmonary interstitial emphysema Pneumomediastinum Pneumothorax Bronchial rupture Air emboli N Engl J Med 2000 May 4;342(18): / Resp Care Clin Nor Am 6:2,2000:

Indications for Mechanical Ventilation. Mechanical Ventilation. Indications for Mechanical Ventilation. Modes. Modes: Volume cycled

Mechanical Ventilation Eric A. Libré, MD VCU School of Medicine Inova Fairfax Hospital and VHC Indications for Mechanical Ventilation Inadequate ventilatory effort Rising pco2 with resp acidosis (7.25)