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(BQ) Part 1 book Essentials of mechanical ventilation has contents: Physiologic effects of mechanical ventilation, ventilator induced lung injury, ventilator associated pneumonia, ventilator liberation... and other contents.
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use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited Your right to use the work may be terminated if you fail to comply with these terms THE WORK IS PROVIDED “AS IS.” MCGRAW-HILL EDUCATION AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE McGraw-Hill Education and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free Neither McGraw-Hill Education nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom McGraw-Hill Education has no responsibility for the content of any information accessed through the work Under no circumstances shall McGraw-Hill Education and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise Dedication For Susan, Terri, Rob, Max, Abby, Lauren, and Matt—who make every day enjoyable D.R.H For my children Robert, Julia, Katie, and Callie, who make it all worthwhile R.M.K Contents Preface Abbreviations Part 1 Principles of Mechanical Ventilation Chapter Physiologic Effects of Mechanical Ventilation Chapter Physiologic Goals of Mechanical Ventilation Chapter Ventilator-Induced Lung Injury Chapter Ventilator-Associated Pneumonia Chapter Ventilator Mode Classification Chapter Traditional Modes of Mechanical Ventilation Chapter Pressure and Volume Ventilation Chapter Advanced Modes of Mechanical Ventilation Chapter Flow Waveforms and I:E Ratios Chapter 10 High Frequency Ventilation Chapter 11 Noninvasive Ventilation Chapter 12 Humidification and the Ventilator Circuit Chapter 13 FIO2, Positive End-Expiratory Pressure, and Mean Airway Pressure Chapter 14 Initial Settings for Mechanical Ventilation Chapter 15 Patient-Ventilator Asynchrony Chapter 16 Ventilator Liberation Part 2 Ventilator Management Chapter 17 Acute Respiratory Distress Syndrome Chapter 18 Obstructive Lung Disease Chapter 19 Chest Trauma Chapter 20 Head Injury Chapter 21 Postoperative Mechanical Ventilation Chapter 22 Neuromuscular Disease Chapter 23 Cardiac Failure Chapter 24 Burns and Inhalation Injury Chapter 25 Bronchopleural Fistula Chapter 26 Drug Overdose Part 3 Monitoring During Mechanical Ventilation Chapter 27 Blood Gases Chapter 28 Pulse Oximetry, Capnography, and Transcutaneous Monitoring Chapter 29 Hemodynamic Monitoring Chapter 30 Basic Pulmonary Mechanics During Mechanical Ventilation Chapter 31 Advanced Pulmonary Mechanics During Mechanical Ventilation Chapter 32 Nutritional Assessment Part 4 Topics Related to Mechanical Ventilation Chapter 33 Airway Management Chapter 34 Airway Clearance Chapter 35 Inhaled Drug Delivery Chapter 36 Emergency Ventilation and Ventilation in a Disaster Chapter 37 Mobilization and Portable Ventilation Chapter 38 Extracorporeal Life Support Index Chapter 22 Neuromuscular Disease • Introduction • Overview Rapid Onset Gradual Onset • Mechanical Ventilation Indications Noninvasive Ventilation Ventilator Settings Monitoring Liberation • In-Exsufflator, Maximum Insufflation Capacity, and Assisted Cough • Points to Remember • Additional Reading Objectives Discuss the pathophysiology of ventilatory failure in patients with neuromuscular disease or chest wall deformities Discuss the indications for invasive and noninvasive ventilation in this patient population Discuss initial ventilator settings for invasive and noninvasive ventilatory support in this patient population Discuss monitoring during and weaning from ventilatory support for patients with neuromuscular disease Discuss the use of the in-exsufflator in patients with neuromuscular disease Introduction Patients with neuromuscular disease or chest wall deformities represent a small percentage of patients receiving ventilatory support However, they also represent a large percentage of patients requiring long-term ventilatory support As these patients usually have normal lungs and the reason for ventilatory assistance is an inability to generate sufficient muscular effort to ventilate, providing mechanical ventilation is much easier in this group than with other groups of patients Overview The neurorespiratory system includes the central nervous system control centers and feedback mechanisms, spinal cord, motor nerves, and the respiratory muscles that affect chest wall and lung movement Neuromuscular respiratory failure can be due to dysfunction of the central or the peripheral nervous system (Tables 22-1 and 22-2) The three main components of neuromuscular respiratory failure are inability to ventilate, inability to cough, and aspiration risk This group of patients can be divided into two general categories—those with a relatively rapid (days to weeks) onset of neuromuscular weakness and those in which neuromuscular weakness is progressive and not reversible Table 22-1 Diseases of the Central Nervous System Associated With Respiratory Dysfunction Table 22-2 Diseases of the Peripheral Nervous System Associated With Respiratory Dysfunction Rapid Onset The two primary diseases in this category are myasthenia gravis and GuillainBarré syndrome This category also includes patients with prolonged paralysis following the use of neuromuscular blocking agents in the ICU and patients with high spinal cord injury These patients do not have lung disease, but reversible neuromuscular weakness requiring ventilatory support for varying periods of time prior to return to a stable state where spontaneous breathing is feasible The exception to this may be the spinal cord-injured patient who may require longterm ventilatory support Of concern with these patients is their perception that their lungs are being ventilated As a result, they require large tidal volumes— sometimes exceeding 10 mL/kg, although this is controversial Because they do not have intrinsic lung disease, plateau pressure (Pplat) is easily kept below 30 cm H2O Gradual Onset Patients with muscular dystrophy, amyotrophic lateral sclerosis, thoracic deformities (severe scoliosis, kyphosis, or kyphoscoliosis), or postpolio syndrome frequently develop gradual muscular weakness over time, in some cases progressing over years Many require periodic mechanical ventilation because of acute pulmonary infections and others require chronic ventilatory support because of progressive deterioration in neuromuscular function For many of these patients, mechanical ventilation is required at some point in their course of disease These patients are good candidates for noninvasive ventilation (NIV) At first, these patients may only need nocturnal ventilation During rapid eye movement (REM) sleep, respiratory control of accessory muscles is lost, resulting in nocturnal hypoventilation when the diaphragm is weak As the disease progresses, further deterioration in neuromuscular function leads to the need for daytime NIV and invasive ventilatory support may be required Mechanical Ventilation Indications Ventilatory support in most cases is indicated because of progressive ventilatory muscle weakness leading to ventilatory failure Oxygenation is not usually an issue Exceptions are the patients with an acquired neuropathy or myopathy following prolonged mechanical ventilation (polyneuropathy or myopathy of critical illness), pneumonia, atelectasis, or pulmonary edema Oxygenation may be an issue in these patients because of the primary pathophysiology leading to ventilatory support However, it is important to remember that most patients with neuromuscular disease develop hypoxemia because they are unable to ventilate If they are ventilated appropriately, the hypoxemia resolves Noninvasive Ventilation Patients with neuromuscular disease can often be managed with NIV NIV has been successfully used in both short-term application and long-term applications NIV is most useful for progressive neuromuscular weakness NIV in the setting of progressive neuromuscular disease is life-prolonging and improves the quality of life, particularly in patients who do not have bulbar involvement Usual criteria for NIV in patients with progressive neuromuscular disease are a Paco2 more than 45 mm Hg while awake, or sleep oximetry demonstrates oxygen saturation less than or equal to 88% for more than or equal to 5 minutes, or maximal inspiratory pressure (PImax) is greater than –60 cm H2O or forced vital capacity (FVC) is less than 50% predicted NIV can be provided using either an oronasal or nasal interface Mouth leak is often problematic, requiring the use of an oronasal mask In patients using daytime NIV, a mouthpiece can be used sometimes NIV is most useful in patients where lung function has not been compromised Typically, an inspiratory positive airway pressure of 8 to 15 cm H2O is used, although higher settings are needed for some patients Unless the patient also has obstructive sleep apnea, an expiratory positive airway pressure of 3 to 4 cm H2O is sufficient A backup rate of 10 to 12 breaths/min is needed to manage periodic breathing Modifications based on air leaks are necessary and large tidal volumes are usually not achievable or necessary A properly fitting interface is necessary to improve tolerance Ventilator Settings Since these patients have normal lung function, invasive ventilation can be accomplished with low pressures and a low FIO2 (Table 22-3) Volumecontrolled ventilation with normal VT and respiratory rate is usually sufficient Although high VT have been recommended by some authorities, that practice is anecdotal and not necessary for most patients Settings of VT and respiratory rate that the patient considers comfortable are recommended (Figure 22-1) Table 22-3 Initial Ventilator Settings in Patients With Neuromuscular Disease Figure 22-1 An algorithm for mechanical ventilation of the patient with neuromuscular disease who does not have underlying lung disease In most cases assist/control continuous mandatory ventilation is the mode of choice If the rate and VT are set to satisfy the patient’s ventilatory demand, many patients allow the ventilator to control ventilation Inspiratory flow waveforms are set per patient’s comfort A low level of positive end-expiratory pressure (PEEP) is set (eg, 5 cm H2O) to prevent atelectasis If large tidal volumes are used, Paco2 can be maintained at a normal level by the addition of 50 to 200 mL of dead space between the ventilator Y-piece and endotracheal tube Use of a very high tidal volume, sometimes with the addition of mechanical dead space to avoid excessive respiratory alkalosis, is the practice in some cervical spine injury centers However, this is controversial and evidence is lacking that this results in better outcomes Before the decision is made to use large tidal volumes, attempts to use more normal tidal volumes should be made If a high tidal volume is used in these patients, it should be decreased to 6 to 8 mL/kg if the patient develops acute respiratory failure such as pneumonia In patients with reduced lung volumes (ie, thoracic deformities or muscular dystrophies), care must be taken not to overdistend the lungs Pplat should be maintained as low as possible (< 30 cm H2O) This requires low tidal volumes (< 8 mL/cm H2O) with more rapid rates (> 15/min) and shorter inspiratory times (< 1 second) Patients with low lung volumes benefit from the use of PEEP Monitoring Periodic monitoring of blood gases is necessary (Table 22-4) However, frequent blood gases are unnecessary because of the lack of intrinsic lung disease Spontaneous VT and respiratory rate, ventilatory pattern, vital capacity (VC), and PImax provide useful information to guide the initiation and termination of ventilatory support Decisions to initiate ventilatory support due to rapid onset disease are commonly made when VC is less than 10 mL/kg ideal body weight and/or PImax more than –20 cm H2O Decisions to begin the process of liberation occur when the above thresholds are reached, and ventilation discontinued when VC is more than 15 mL/kg and PImax is less than –30 cm H2O with no deterioration after extended periods of spontaneous breathing (> 1 hour) Table 22-4 Monitoring for the Mechanically Ventilated Patient With Neuromuscular Disease or Chest Wall Deformity • Spontaneous tidal volume and respiratory rate • Vital capacity and maximal inspiratory pressure • Periodic arterial blood gases Liberation Since these patients are committed to ventilatory support because a primary neuromuscular deficit has resulted in ventilatory muscle weakness and fatigue, liberation can only occur if these indications for ventilation have been reversed In some patients with severe irreversible disease (eg, high spinal cord injury, end-stage amyotrophic lateral sclerosis), liberation will not be possible and longterm ventilation strategies must be considered In those patients where the acute process is reversible, appropriate therapy and time must be allowed for reversal of the neuromuscular deficit Some patients will require tracheostomy, but this should only be considered if it is consistent with the patient’s wishes The first goal is ventilator independence during waking hours with support at night Complete ventilator independence is a secondary goal Because of the nature of these diseases, liberation may take weeks to achieve, and care must be exercised not to fatigue the respiratory muscles during spontaneous breathing trials Patients should not be pushed to the point that ventilatory pattern changes, VC and PImax deteriorate, or hypercarbia develops With many patients in this group, the decision to maintain long-term ventilatory support must be made at some point in their disease process Specific guidelines for when this should occur are lacking However, nocturnal NIV should be considered whenever daytime baseline Paco2 is more than 45 mm Hg When the patient’s ventilatory reserve is markedly compromised, even small stressors may facilitate failure These patients’ ability to perform activities of daily living and to handle periodic stress is increased with nocturnal NIV In-Exsufflator, Maximum Insufflation Capacity, and Assisted Cough Patients with neuromuscular diseases and chest wall deformities with ventilatory difficulties are ideal candidates for the in-exsufflator (cough assist) This device simulates a cough by inflating the lungs with pressure, followed by a negative airway pressure to produce a high expiratory flow This sequence is repeated as necessary to clear secretions There is considerable anecdotal experience with this therapy in patients with neuromuscular disease Many of these patients indicate no need for tracheal suctioning when the in-exsufflator is used Initial application of the in-exsufflator requires low settings to allow acclimation The inspiratory pressure is then adjusted to 25 to 35 cm H2O applied for 1 or 2 seconds followed by an expiratory pressure up to –40 cm H2O for about 1 or 2 seconds Treatment periods consist of five to six breaths, followed by rest, and repeated until secretions are effectively cleared Hyperinflation therapy may be of benefit for patients with neuromuscular disease This has been described as the maximum insufflation capacity (MIC) It is accomplished by the patient taking a deep breath, holding it, and then stacking consecutively delivered tidal volumes to the maximum volume that can be held with a closed glottis The air is delivered from a manual or portable volume ventilator This technique is limited by the ability of the patient to close the glottis (eg, bulbar disease) Some clinicians train the patient in this technique when the vital capacity becomes less than 2 L MIC can be combined with manually assisted cough to improve secretion clearance A manually assisted cough consists of an abdominal thrust and/or chest compression (tussive squeeze) after a deep inflation This can be quantified using a peak flow meter A peak cough flow of more than 160 L/min is needed to adequately clear airway secretions The in-exsufflator is usually indicated if the patient with neuromuscular disease cannot generate an unassisted or assisted peak flow more than 160 L/min Points to Remember • Most patients with decreased neuromuscular function do not have intrinsic lung disease • Two subgroups of patients are usually encountered—those with acute onset of weakness that is short-term and reversible, and those with progressive weakness that is nonreversible • Most patients with a gradual onset of weakness are candidates for noninvasive ventilation • Invasive mechanical ventilation is indicated with acute ventilatory failure caused by muscular weakness • In those patients without reduction in lung volumes, larger tidal volumes (≥ 8 mL/kg), long inspiratory times (> 1 second), and moderate rates (≥ 15/min) may be necessary for patient’s comfort • Mechanical dead space may be necessary in patients requiring large VT and V.E • Use small VT (≤ 8 mL/kg), rapid rates (> 20/min), and short inspiratory times (≤ 1 second) in patients with reduced lung volumes • Monitor spontaneous ventilatory capabilities: VT, rate, VC, PImax, and ventilatory pattern • Liberation, when possible, is accomplished by increasing periods of spontaneous breathing trials interspersed with ventilatory support • The mechanical in-exsufflator is useful to mobilize secretions in patients with neuromuscular disease and a weak cough • Patients unable to maintain daytime Paco2 less than 45 mm Hg are candidates for nocturnal chronic ventilatory support Additional Reading Ambrosino N, Carpenè N, Gherardi M Chronic respiratory care for neuromuscular diseases in adults Eur Respir J 2009;34:444-451 Bach JR, GonÇalves MR, Hon A, et al Changing trends in the management of end-stage neuromuscular respiratory muscle failure: recommendations of an international consensus Am J Phys Med Rehabil 2013;92:267-277 Bedlack RS Amyotrophic lateral sclerosis: current practice and future treatments Curr Opin Neurol 2010;23:524-529 Beghi E, Chiò A, Couratier P, et al The epidemiology and treatment of ALS: focus on the heterogeneity of the disease and critical appraisal of therapeutic trials Amyotroph Lateral Scler 2011;12:1-10 Benditt JO, Boitano LJ Pulmonary issues in patients with chronic neuromuscular disease Am J Respir Crit Care Med 2013;187:1046-1055 Benditt JO Full-time noninvasive ventilation: possible and desirable Respir Care 2006;51: 1005-1015 Benditt JO Initiating noninvasive management of respiratory insufficiency in neuromuscular disease Pediatrics 2009;123;S236-S238 Benditt JO The neuromuscular respiratory system: physiology, pathophysiology, and a respiratory care approach to patients Respir Care 2006;51:829-839 Bershad EM, Feen ES, Suarez JI Myasthenia gravis crisis South Med J 2008;101:63-69 Birnkrant DJ, Bushby K, Amin RS, et al The respiratory management of patients with Duchenne muscular dystrophy: a DMD care considerations working group specialty article Ped Pulm 2010;45:739-748 Boitano LJ Equipment options for cough augmentation, ventilation, and noninvasive interfaces in neuromuscular respiratory management Pediatrics 2009;123(Suppl 4):S226-S230 Garguilo M, Leroux K, Lejaille M, et al Patient-controlled positive endexpiratory pressure with neuromuscular disease: effect on speech in patients with tracheostomy and mechanical ventilation support Chest 2013;143:1243-1251 Hess DR The growing role of noninvasive ventilation in patients requiring prolonged mechanical ventilation Respir Care 2006;51:896-911 Homnick DN Mechanical insufflation-exsufflation for airway mucus clearance Respir Care 2007;52:1296-1307 Lofaso F, Prigent H, Tiffreau V, et al Long term mechanical ventilation equipment for neuromuscular patients: meeting the expectations of patients and prescribers Respir Care 2014;59:97-106 Lyall RA, Donaldson N, Fleming T, et al A prospective study of quality of life in ALS patients treated with noninvasive ventilation Neurology 2001;57:153-156 Moran FC, Spittle A, Delany C Effect of home mechanical in-exsufflation on hospitalisation and life-style in neuromuscular disease : a pilot study J Paediatr Child Health 2013;49: 233-237 Radunovic A, Annane D, Rafiq MK, Mustfa N Mechanical ventilation for amyotrophic lateral sclerosis/motor neuron disease Cochrane Database Syst Rev 2013 28;3:CD004427 Wolfe LF, Joyce NC, McDonald CM, et al Management of pulmonary complications in neuromuscular disease Phys Med Rehabil Clin N Am 2012;23:829-853 ... the publisher ISBN: 978-0-07 -17 7283-9 MHID: 0-07 -17 7283-9 The material in this eBook also appears in the print version of this title: ISBN: 978-0-07 -17 715 1 -1, MHID: 0-07 -17 715 1-4 eBook conversion by codeMantra... Contents Preface Abbreviations Part 1 Principles of Mechanical Ventilation Chapter Physiologic Effects of Mechanical Ventilation Chapter Physiologic Goals of Mechanical Ventilation Chapter Ventilator-Induced Lung Injury... There have been many advances in the practice of mechanical ventilation over the past 10 years Hence, much of the book is rewritten Like previous editions, the book is divided into four parts Part 1, Principles of Mechanical Ventilation, describes basic principles of mechanical ventilation and then