Copyright © 2006 by Mosby, Inc. Slide 1 Chapter 45 Respiratory Failure
Copyright © 2006 by Mosby, Inc. Slide 2 Mechanical Ventilation Mechanical ventilation may be delivered by: Endotracheal tube (most common) Tracheostomy Face mask Cuirass-type device
Copyright © 2006 by Mosby, Inc. Slide 3 Mechanical Ventilation Ventilator modes include: Assist-control (A/C) Synchronized intermittent mandatory ventilation (SIMV) With or without pressure support (PS) With or without pressure support (PS) Less commonly used modes include: SIMV alone SIMV alone Inverse-rate ventilation (IRV) Inverse-rate ventilation (IRV) Airway pressure release ventilation (APRV) Airway pressure release ventilation (APRV)
Copyright © 2006 by Mosby, Inc. Slide 4 Mechanical Ventilation The goal of mechanical ventilation is to totally or partially replace the gas exchange function of the lungs—with as few complications as possible
Copyright © 2006 by Mosby, Inc. Slide 5 Mechanical Ventilation The objectives of mechanical ventilation are to: Improve and maintain alveolar ventilation To ensure adequate CO 2 and pH homeostasis, oxygenation, and lung inflation To reduce the work of breathing
Copyright © 2006 by Mosby, Inc. Slide 6 Mechanical Ventilation Achievement of these objectives Reverses acute respiratory acidosis with hypoxemia Also called acute ventilatory failure with hypoxemia Also called acute ventilatory failure with hypoxemia Relieves patient discomfort Reverses or prevents atelectasis Reverses muscle fatigue Stabilizes the chest wall Allows sedation and/or neuromuscular blockade Decreases systemic or myocardial oxygen consumption
Copyright © 2006 by Mosby, Inc. Slide 7 Etiology and Pathogenesis Four conditions that commonly require mechanical ventilation Acute respiratory failure (ARF)—74% Also called acute ventilatory failure (AVF) Also called acute ventilatory failure (AVF) Exacerbation of chronic obstructive pulmonary disease (COPD)—16% Coma—7% Neuromuscular disease—3%
Copyright © 2006 by Mosby, Inc. Slide 8 Etiology and Pathogenesis The causes of ARF include the following: Postoperative complications Sepsis Trauma Pneumonia Heart failure ARDS Aspiration Others (miscellaneous)
Copyright © 2006 by Mosby, Inc. Slide 9 Etiology and Pathogenesis All of the clinical scenarios described in Chapter 9 may (and do, if left untreated) lead to respiratory failure It is crucial that the RCP be able to recognize the clinical scenarios caused by: The six most common anatomic alterations of the lungs (see Chapter 9), and The respiratory disorders that produce them (see Table 45-1) page 540
Copyright © 2006 by Mosby, Inc. Slide 10 Figure 9-7. Atelectasis clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 11 Figure 9-8. Alveolar consolidation clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 12 Figure 9-9. Increased alveolar-capillary membrane thickness clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 13 Figure Bronchospasm clinical scenario (e.g., asthma).
Copyright © 2006 by Mosby, Inc. Slide 14 Figure Excessive bronchial secretions clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 15 Figure Distal airway and alveolar weakening clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 16 Box Conditions That May Develop in the Hospital and Complicate the Management of Patients Receiving Mechanical Ventilation CCardiovascular events AAcute respiratory distress syndrome PPulmonary embolism/infarction PPneumothorax NNeuropsychiatric complications EElectrolyte and fluid imbalance UUpper airway obstruction MMalnutrition OOxygen toxicity NNonsense data IInfection AAtelectasis
Copyright © 2006 by Mosby, Inc. Slide 17 Table 45-1.
Copyright © 2006 by Mosby, Inc. Slide 18 Table 45-1., cont.
Copyright © 2006 by Mosby, Inc. Slide 19 Overview of the Cardiopulmonary Clinical Manifestations Associated with ACUTE RESPIRATORY FAILURE At the right side of each of the clinical scenarios (see Figures 9-7 though 9-12) is an overview of the signs and symptoms of the various diseases that, when allowed to proceed to their “worst case scenario,” end in acute respiratory failure The following are clinical manifestations of acute respiratory failure that are indications for mechanical ventilation
Copyright © 2006 by Mosby, Inc. Slide 20 Clinical Manifestations of Acute Respiratory Failure Somnolence proceeding to coma An indication of alveolar hypoventilation Severe and worsening hypoxemia Excessive work of breathing Inadequate lung expansion
Copyright © 2006 by Mosby, Inc. Slide 21 Clinical Indicators Clinical Indicators Respiratory acidosis (acute ventilatory failure) Pa CO 2, pH, PaO 2, Sp O 2 Agitation, tachycardia, pulse >120, A-aO 2, Pa O 2 /FI O 2, shunt fraction, venous admixture
Copyright © 2006 by Mosby, Inc. Slide 22 Clinical Indicators Clinical Indicators Dyspnea, ventilatory effect, physiologic dead space, respiratory rate, diaphoresis, use of accessory muscles, abdominal paradox Atelectasis, ventilatory capacity, maximum inspiratory pressure, maximum voluntary ventilation
Copyright © 2006 by Mosby, Inc. Slide 23 The Fifth Protocol— General Management The Fifth Protocol— General Management Do any contraindications to invasive mechanical ventilation exist? Patient’s wishes to the contrary Needless prolongation of the patient’s life
Copyright © 2006 by Mosby, Inc. Slide 24 Ventilator Management and Ventilator Weaning Modes More than 90% of patients requiring ventilatory support in the United States are ventilated with assist/control alone Or in combination with PS ventilation Initial tidal volume (V T ) settings 6 to 10 ml/kg ideal body weight 5 to 6 ml/kg for recent “lung protective strategies”
Copyright © 2006 by Mosby, Inc. Slide 25 Ventilator Management and Ventilator Weaning Modes In routine cases, 10 to 12 ml/kg is used routinely Tidal volumes as great as 16 ml/kg have been used to minimize atelectasis in acute neuromuscular diseases And initial PEEP setting of 5 cm H 2 O is used in most cases However, PEEP should not be used in patients with acute brain injury, and cautiously in COPD patients
Copyright © 2006 by Mosby, Inc. Slide 26 Ventilator Management and Ventilator Weaning Modes Except in patients with anoxic brain or myocardial injuries, permissive hypercapnia is allowed V T and RR are adjusted to achieve the predetermined pH and plateau pressure goals The inspiratory flow is set above spontaneous breathing patient demand
Copyright © 2006 by Mosby, Inc. Slide 27 Ventilator Management and Ventilator Weaning Modes Use of other protocols Bronchopulmonary hygiene therapy protocol Hyperinflation therapy protocol Aerosolized medication protocol
Copyright © 2006 by Mosby, Inc. Slide 28 Disorder: Normal Lung Mechanics —but Patient Has Apnea Disease characteristics Normal compliance and airway resistance Ventilator mode Volume ventilation in the AC or SIMV mode Or pressure ventilation—either PRVC or PC Tidal volume and respiratory rate 10 to 12 ml/kg 6 to 10 bpm 6 to 10 bpm when SIMV mode is used 6 to 10 bpm when SIMV mode is used Table 9-3 Common Ventilatory Management Strategies
Copyright © 2006 by Mosby, Inc. Slide 29 Normal Lung Mechanics, cont. Flow rate 60 to 80 L/min I:E ratio 1:2 FIO 2 Low to moderate General goals and/or concerns Care to ensure plateau pressure of 30 cm H 2 O or less Smaller tidal volumes (<7 ml/kg) should be avoided because atelectasis can develop Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 30 Disorder: Chronic Obstructive Pulmonary Disease (COPD) Disease characteristics High lung compliance and high airway resistance Ventilator mode Volume ventilation in the AC or SIMV mode Or pressure ventilation—either PRVC or PC Noninvasive positive pressure ventilation (NPPV) is good alternative Tidal volume and respiratory rate Good starting point: 10 ml/kg and 10 to 12 bpm A small tidal volume (5-8 ml/kg) and 8 to 10 bpm with increased flow rates to allow adequate expiratory time Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 31 COPD, cont. Flow rate 60 L/min I:E ratio 1:2 or 1:3 FIO 2 Low to moderate General goals and/or concerns Air-trapping and auto-PEEP can occur when expiratory time is too short ↑ Expiratory time to offset auto-PEEP May ↑ inspiratory flow up to 100 L/min to ↑ expiratory time May ↓ V T or rate to ↑ expiratory time Do not overventilate COPD patients with chronically high Pa CO 2 levels Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 32 Disorder: Acute Asthmatic Episode Disease characteristics High airway resistance Ventilator mode SIMV mode is recommended—to offset air-trapping Tidal volume and respiratory rate Good starting point: 8 to 10 ml/kg Rate of 10 to 12 bpm When air-trapping is extensive, a lower tidal volume (5-6 ml/kg) and slower rate may be required Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 33 Acute Asthmatic Episode, cont. Flow rate 60 L/min I:E ratio 1:2 or 1:3 FIO 2 Start at 100% and titrate downward per SpO 2 and ABGs General goals and/or concerns In severe cases, the development of auto-PEEP may be inevitable With controlled ventilation, a small amount of PEEP to offset auto-PEEP may be cautiously applied Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 34 Disorder: Acute Respiratory Distress Syndrome Disease characteristics Diffuse, uneven alveolar injury Ventilator mode Volume ventilation in the AC or SIMV mode Or pressure ventilation—PRVC or PC Tidal volume and respiratory rate Typically started at low tidal volumes and higher rates 8 ml/kg and adjusted downward to 6 ml/kg or 4 ml/kg 8 ml/kg and adjusted downward to 6 ml/kg or 4 ml/kg Respiratory rate as high as 35 bpm Respiratory rate as high as 35 bpm Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 35 Acute Respiratory Distress Syndrome, Cont. Flow rate 60 to 80 L/min I:E ratio 1:1 or 1:2 Do what is necessary to meet a rapid respiratory rate FIO 2 Less than 0.6 if possible General goals and/or concerns Goal is to limit transpulmonary pressures 30 cm H 2 O of less if possible PEEP is usually needed to prevent atelectasis Permissive hypercapnia may be allowed Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 36 Disorder: Postoperative Ventilatory Support Disease characteristics Often normal compliance and airway resistance Ventilator mode SIMV with pressure support Or AC volume ventilation Or pressure ventilation—either PRVC or PC Tidal volume and respiratory rate Good starting point: 10 to 12 ml/kg Rate of 10 to 12 bpm However, larger tidal volumes (12-15 ml/kg) and slower rates (6-10 bpm) may be used to maintain lung volume However, larger tidal volumes (12-15 ml/kg) and slower rates (6-10 bpm) may be used to maintain lung volume Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 37 Postoperative Ventilatory Support, Cont. Flow rate 60 L/min I:E ratio 1:2 FIO 2 Low to moderate General goals and/or concerns PEEP or CPAP of 3 to 5 cm H 2 O may be applied to offset atelectasis Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 38 Disorder: Neuromuscular Disorder Disease characteristics Normal compliance and airway resistance Ventilator mode Volume ventilation in the AC or SIMV mode Or pressure ventilation—either PRVC or PC Tidal volume and respiratory rate Good starting point: 12 to 15 ml/kg Rate of 10 to 12 bpm Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 39 Neuromuscular Disorder, cont. Flow rate 60 L/min I:E ratio 1:2 FIO 2 Low to moderate General goals and/or concerns PEEP of 3 to 5 cm H 2 O may be applied to offset atelectasis Table 9-3 Common Ventilatory Management Strategies, cont.
Copyright © 2006 by Mosby, Inc. Slide 40 Classroom Discussion Case Study: Acute Respiratory Failure