High-Acuity Nursing, 6th Edition

Mechanical Ventilation Objectives: 1. Identify criteria used to determine the need for mechanical ventilator support. 2. Select the equipment necessary to initiate mechanical ventilation. 3. Describe the modes of mechanical ventilation. 4. Explain the commonly monitored ventilator settings. 5. Briefly explain noninvasive ventilator support. 6. Discuss the major complications of mechanical ventilation with intubation. 7. Describe artificial airways and implications for practice. 8. Describe the nursing care of the patient requiring ventilatory support. 9. Describe the process of weaning a patient from mechanical ventilation and the nurse’s role in this process. I. Determining the Need for Ventilatory Support 1. Mechanical ventilators augment and support the ventilation portion of the respiratory process. Mechanical ventilators place a patient at risk for major complications, so the decision to place a patient on a ventilator is a serious one. 2. Criteria used to decide to place a patient on a ventilator: a) Acute ventilator failure (AVF): PaCO2 greater than 50 mm Hg, pH less than 7.30 b) Acute hypoxemia: PaO2 less than 60 mm Hg c) Respiratory rate: greater than 35 breaths/minute d) Vital capacity (VC): less than 15 mL/kg (normal: 65–75) e) Maximum inspiratory pressure (MIP): less than ?20 cm H2O (normal: -50–-100 cm H2O) A. Acute ventilator failure 1. Acute ventilator failure (AVF) is the most common indication for ventilator support. It is when the lungs are unable to maintain adequate alveolar ventilation. One exception is patients with COPD. B. Acute oxygenation failure 1. The second major indication for mechanical ventilator support is hypoxemia, which is frequently quantified as a Pao2 of less than 60 mm Hg (the clinical definition of oxygenation failure). C. Pulmonary mechanics 1. Pulmonary mechanics testing may be used to decide whether mechanical ventilator support is needed. The most common tests are: a) Vital capacity: maximum amount of air expired after maximum inspiration b) Maximum inspiratory pressure: amount of negative pressure that a person can generate from maximum inspiratory effort c) Respiratory rate D. Special considerations 1. Age-related changes in pulmonary physiology place the elderly at risk for respiratory failure. Common age-related changes are: a) Decreased chest wall compliance b) Decreased oxygenation c) Decreased lung volume and strength PowerPoint Slides 1. Ventilation criteria AVF Acute hypoxemia Respiratory rate VC MIP VE 2. Common indications for ventilator support Acute ventilator failure (AVF) Hypoxemia 3. Most common pulmonary mechanics tests Vital capacity Maximum inspiratory pressure Respiratory rate 4. Age-related changes in pulmonary physiology Decreased chest wall compliance Decreased oxygenation Decreased lung volume and strength II. Required Equipment for Mechanical Ventilation A. Initial equipment necessary for establishment of a patent airway 1. Endotracheal tubes come in various sizes. The size to use depends mostly on age of patient. a) Choice of endotracheal tube size and route (1) Endotracheal tubes can take different routes. b) Intubation equipment (1) Other required equipment with an ET: (a) Stylet (b) Topical anesthetic (c) Laryngoscope handle with blade attached (d) Magill forceps (e) Suction machine (f) Suction catheters, Yankauer suction tip (g) Syringe for cuff inflation (h) Water-soluble lubricant (i) Personal protective equipment (j) Sedative medication 2. Tracheostomy tubes: tracheostomy usually used with patients who had head or neck surgery or an upper airway obstruction 3. Securing the artificial airway a) Tube can be secured with adhesive tape; however, commercially available ET tube stabilizers are the preferred method of securing the ET tube commonly are secured with twill tape or a commercially available tracheostomy holder with Velcro fasteners. b) Tube also may be initially sutured in place to prevent accidental dislodgment. 4. Supportive equipment   a) In addition to an airway, other equipment is needed for mechanical ventilation: two oxygen sources b) Disposable sterile suction kits or sterile suction catheters, gloves, containers, sterile water. c) Oral pharyngeal airway or a bite block if the oral route is used. d) Cuff manometer to check the ET tube cuff pressure on a regular basis. e) Manual resuscitation bag to provide adequate backup in case of ventilator failure and for suctioning. f) If positive end-expiratory pressure (PEEP) is to be used on the ventilator, a manual resuscitation bag with a PEEP attachment is recommended. g) Secure intravenous access for medication administration. h) Sedation and muscle relaxant agents 5. Post-intubation assessment. a) An immediate method to ensure proper tube placement is to measure carbon dioxide using capnography or a disposable CO detector (Goodrich, 2011). PowerPoint Slides 1a. Endotracheal tubes (ET) Various sizes; size to use depends mostly on age of patient Different routes Other required equipment 1b. Tracheostomy tubes: usually used with patients who had head or neck surgery or an upper airway obstruction 2. Securing the artificial airway Adhesive tape different routes Tube stabilizers Sutured in place 3. Postintubation assessment Measure carbon dioxide using capnography Disposable CO2 detector III. Types of Mechanical Ventilators A. Negative pressure ventilators 1. Negative pressure ventilators use negative pressure applied to the thorax by external means. a) Patient’s body is encased in an airtight unit. b) Air pressure in the unit is reduced to below atmospheric pressure, and air moves into the lungs. c) Negative pressure ventilators can help patients who have chronic hypoventilation or who need intermittent ventilator support (such as during sleep). B. Positive pressure ventilators 1. Positive pressure ventilators use an artificial airway to deliver support. Gases are delivered into the lungs. 2. Positive pressure ventilators have four cycling mechanisms: a) Pressure-cycled: Delivers preset pressure into lungs. b) Volume-cycled: Delivers preset volume of gas into lungs. c) Time-cycled: Length of time for inspiration is controlled. d) Flow-cycled: Pre-set pressure augments the patient’s inspiratory effort as long as patient breathes at certain flow rate. PowerPoint Slides 1. Negative pressure ventilators Use negative pressure applied to the thorax by external means. Patient’s body is encased in an airtight unit. Air pressure reduced to below atmospheric pressure Air moves into lungs. 2. Positive pressure ventilators 3. Positive pressure ventilators have four cycling mechanisms: Pressure-cycled Volume-cycled Time-cycled Flow-cycled IV. Commonly Monitored Ventilator Settings 1. Positive pressure ventilators offer variables that can be adjusted to meet the individual patient’s needs. The most commonly monitored settings are: a) Tidal volume (Vt): amount of air that moves into and out of lungs. b) Fraction of inspired oxygen (FIO2) c) Respiratory rate (f) d) Positive end-expiratory pressure (PEEP) e) Continuous positive airway pressure (CPAP) f) Pressure support (PS) g) Peak pressure (peak) or peak inspiratory pressure (PIP). A. Tidal volume 1. Adverse effects of high tidal volumes a) Barotrauma: A tidal volume of more than 12 mL/kg may overdistend the alveoli, increasing pressure, which may result in injury. b) Volutrauma: increases the permeability of the lungs’ microvasculature, which may result in pulmonary edema. 2. Normal-volume settings: selection of tidal volume may range from 4 to 12 mL/kg of ideal body weight (adult) based on the patient’s lung status 3. Sigh: refers to intermittent hyperinflation of the lungs. B. Fraction of inspired oxygen 1. Fio is commonly set at 0.5 to 1.0 to deliver 50 percent to 100 percent oxygen to the patient. C. Positive end-expiratory pressure 1. PEEP is set to provide pressure at the end of expiration, to prevent alveolar collapse. Theoretically, PEEP supports oxygenation and levels of 5cm H2O. D. Ventilation modes 1. Assist-control mode: sensitive to patient’s inspiratory effort but able to deliver breath at preset rate as a backup. a) Advantages: Every breath is guaranteed, set tidal volume, takes over work of breathing, respiratory muscles rest. b) Disadvantages: risk of hyperventilation, respiratory muscle atrophy. 2. Synchronous intermittent mandatory ventilation mode: Patient breathes spontaneously, with the ventilator circuit doing much of the work of breathing. a) Advantages: Prevents respiratory muscle atrophy, decreased risk of hyperventilation, better ventilation–perfusion distribution b) Disadvantages: tachypnea and fatigue if set rate too low 3. Pressure support ventilation mode pressure support ventilation (PSV) adjunct weaning mode. Applies positive pressure. Triggered by patient’s spontaneous breathing and decreases effort needed to achieve tidal volume. a) Advantages: Improved patient–ventilator synchrony, prevents respiratory muscle atrophy, facilitates weaning b) Disadvantages: Requires spontaneous respiratory effort, tachypnea and fatigue if pressure support is too low 4. Pressure-regulated volume-controlled mode (PRVC) dual control mode: Rate and tidal volume are preset, and breaths can be initiated by patient or the ventilator. a) Advantages: guaranteed VE, improved patient–ventilator synchrony, decreased risk of barotrauma. b) Disadvantages: Respiratory muscle atrophy can result in unequal ventilation–perfusion distribution. 5. High frequency oscillating ventilation (HFV): combines high respiratory rates, with excess rates of 60 and tidal volumes smaller than anatomical dead space. E. Respiratory rate 1. Respiratory rate: Minute ventilation is amount of air that moves in and out of the lungs in one minute. Normal is f:8 t0 12 minute. Tidal volume and rate are the two variables that make up minute ventilation. F. Peak airway pressure or peak inspiratory pressure 1. Amount of pressure needed to deliver tidal volume G. Alarms 1. Low exhaled volume alarm indicates loss of tidal volume or a leak in the system. H. High-pressure alarm 1. Any patient action or problem that increases airway resistance can trigger this alarm; for example, coughing, biting on the tube, or secretions in the airway. I. Initial ventilator settings 1. Initial settings may be determined by the provider or the respiratory therapist. PowerPoint Slides 1. Positive pressure ventilators variables Continuous positive airway pressure (CPAP) Respiratory rate VT: normal FIO2 PEEP PS Peak or (PIP) 2. Adverse effects of high tidal volumes Barotrauma: A tidal volume of more than 12 mL/kg may overdistend the alveoli, increasing pressure, which may result in injury. Volutrauma. 3. Four ventilation modes Assist-control mode Synchronized intermittent mandatory ventilation Pressure support ventilation Pressure-regulated volume controlled mode 4. Advantages and disadvantages of modes Assist-control (AC) Synchronized intermittent mandatory ventilation (SIMV) Pressure support ventilation (PSV) Pressure-regulated volume controlled ventilation (PRVC) 5. Respiratory rate: minute ventilation = air that moves in and out of lungs in 1 minute. Normal = f:8 to 12 minute. 6. PEEP: continuous positive airway pressure (CPAP) or positive end-expiratory pressure. Main indication = oxygen-refractory hypoxemia. 7. Peak airway or peak inspiratory pressure 8. Two most often triggered alarms Low exhaled volume alarm High pressure alarm V. Noninvasive Alternatives to Mechanical Ventilation 1. The use of positive pressure and an artificial airway places a patient at risk for complications and increased morbidity/mortality. Noninvasive ventilation methods have been developed. Two main types of noninvasive methods: a) Noninvasive positive pressure ventilation (NIPPV or NPPV) b) Continuous positive airway pressure (CPAP) A. Noninvasive intermittent positive pressure ventilation is a way to provide ventilation support without intubation. 1. Masks/Interfaces use a ventilator and an interface—usually a noronasal mask, but can also be a nasal pillow, full-face mask, or helmet. 2. Noninvasive Ventilation a) Standard ICU/acute care ventilators b) Portable ventilators c) Bilevel devices 3. Indications and contraindications for use a) At home, NIPPV is used mainly for patients who cannot fully support their own breathing for prolonged periods. In the ICU, it is used for patients in acute respiratory distress (to avoid intubation). (1) Used successfully with patients with hypercapnia (such as those with COPD) and post-surgery patients. (2) Patients with unstable hemodynamic status, cardiac dysrhythmia, or myocardial ischemia, or who are unable to clear their own secretions or maintain airway patency, are contraindicated for use of NIPPV. B. Continuous positive airway pressure (CPAP) 1. CPAP is closely related to NPPV. a) Provides a continuous level of positive airway pressure for a spontaneously breathing person. b) Unlike NPPV, CPAP does not provide assisted ventilation upon inspiration. c) CPAP does not require mechanical vent; it uses a special flow generator (a blower) and a mask. d) CPAP used mostly for obstructive sleep apnea. C. Complications of NIPPV 1. Complications of NIPPV are same as those of regular positive pressure mechanical ventilation (see Learning Objective 6), although not as severe. a) The use of a mask has its own special complications such as skin irritation, aspiration, and conjunctivitis. b) NIPPV requires the nurse to offer the patient a combination of explanations, coaching, and demonstrations. D. Nursing considerations 1. To best assure a patient’s success in using NIPPV, a combination of explanations, patience, and coaching is required. 2. The therapy should be explained and demonstrated at each step, giving the patient an opportunity to ask questions and adapt to the sensations of the masks and air pressures. PowerPoint Slides 1. Two main types of noninvasive methods Noninvasive positive pressure ventilation Continuous positive airway pressure 2. NIPPV provides ventilation support without intubation. 3. Any positive pressure ventilator can be used for NIPPV. 4. NIPV used: At home For periods in ICU 5. CPAP Provides a continuous level of positive airway pressure for a spontaneously breathing person Does not provide assisted ventilation upon inspiration CPAP does not require mechanical vent; uses a blower and a mask Use of a mask 6. With NIPPV, the nurse offers: Explanations Coaching Demonstrations VI. Major Complications of Mechanical Ventilation And Artificial Airways 1. Positive pressure ventilation can result in complications involving nearly all body systems: cardiovascular, pulmonary, neurovascular, renal, and gastrointestinal. A. Cardiovascular complications 1. Cardiovascular a) Decreased cardiac output b) Decreased preload c) Decreased stroke volume B. Pulmonary complications 1. The distribution of gases to the alveoli normally favors the peripheral and dependent lung areas. C. Altered ventilation and perfusion 1. Barotrauma/volutrauma a) There is increasing evidence that the pulmonary injury associated with PPV results from alveolar distention created by a combination of excessive alveolar pressure (barotrauma) and volume (volutrauma). 2. Oxygen toxicity a) Oxygen toxicity damages the endothelial lining of the lungs and decreases alveolar macrophage activity. It also decreases mucous and surfactant production. 3. Ventilator-associated pneumonia (VAP) a) Nosocomial pulmonary infection is a common major complication of mechanical ventilation that develops in patients intubated for more than 48 hours. D. Neurovascular complications 1. PPV can cause a change in neurovascular status through two major mechanisms: increased intracranial pressure (ICP); and decreased cerebral perfusion pressure (CPP). E. Renal complications 1. Decreased cardiac output 2. Redistribution of renal blood flow 3. Hormonal alterations F. Gastrointestinal complications 1. Stress ulcers from gastric hyperacidity or a visceral hypoxic episode 2. Gastrointestinal bleeding 3. Hepatic dysfunction PowerPoint Slides 1. Positive pressure ventilation can result in complications. 2. Cardiovascular complications 3. Pulmonary complications 4. Neurovascular complications 5. Renal complications 6. Gastrointestinal complications VII. Artificial Airway Complications 1. Artificial airways have their own set of complications that are primarily related to bypassing the normal upper airway defenses that warm and humidify the air. A. Nasal/oral damage 1. Nasal damage a) The airway can traumatize nasal mucous membranes. b) Ischemia and necrosis of the nares can develop from pressure of tube on nasal wall. c) A tube can block Eustachian tubes, which can lead to ear infections. 2. Oral damage a) Pressure can cause ulceration or necrosis of inner cheek or lip. 3. Cuff trauma a) Cuff pressure can cause tracheal and laryngeal injury. b) Decreased blood flow to areas can lead to necrosis, which in turn can lead to fistulas, fibrosis, and ulceration. c) Damage to vocal cords. d) Proper monitoring of cuff pressure and use of correct tube size can significantly decrease risk of cuff complications. 4. Tracheostomy Tubes. a) Tracheomalacia. (1) Acquired tracheomalacia, weakening or erosion of the tracheal cartilage, is a rare complication that can arise when tracheal wall tissue becomes damaged from the presence of the tube, cuff, or suctioning over a prolonged period of time. b) Granulation tissue formation (1) Granulation tissue formation can cause obstruction to airflow. Laryngoscopy can identify the degree of problem, c) Stoma Erosion (1) Can develop as the stoma size is enlarged in patients with tracheostomies. PowerPoint Slides 1. Airways have their own specific set of complications. 2. Nasal damage. 3. Oral damage. 4. Cuff trauma. 5. Tracheostomy tubes. VIII. Care of the Patient Requiring Mechanical Ventilation 1. The goals of nursing management can be divided into physiologic needs and psychosocial needs. A. Nursing management of physiologic needs 1. Supporting a patient’s physiologic needs involves: a) Promoting optimal oxygenation. b) Treating impaired gas exchange. c) Providing adequate ventilation. d) Clearing the airway: (1) ABCs: airway, breathing, and clearance. (2) Suctioning of secretions. e) Protecting the airway. f) Supporting tissue perfusion. g) Providing adequate nutrition. 2. Ineffective airway clearance a) Excessive secretions are removed by suctioning the artificial airway on an as-necessary basis, which may be every few minutes during initial intubation or several times a shift with ongoing intubation. b) Thick secretions: properly hydrating the patient is an important means of thinning secretions because secretions are composed primarily of water. c) Pooled secretions can cause obstruction of major airways or can plug the tip of the artificial airway. 3. Impaired gas exchange can involve problems of oxygenation, problems of CO2 elimination, or often both. 4. Ineffective breathing pattern a) Alveolar hyperventilation b) Alveolar hypoventilation 5. Protection of the airway must be taken to minimize the possibility of dislodgment, which could precipitate respiratory compromise. 6. Alteration in cardiac output. 7. Alteration in nutrition: collaboration with the dietitian and provider allows for nutritional assessment and formula delivery to meet each individual’s needs. B. Nursing management of psychosocial needs 1. Anxiety and pain a) High-acuity patients, in general, are at high risk for experiencing pain and anxiety related to their underlying illness, procedures, immobility, routine care, and the critical care environment itself. 2. Sleep pattern disturbance a) Airway clearance and other maintenance nursing interventions frequently require disturbing a resting or sleeping high-acuity patient. 3. Communication and sensation a) The presence of an artificial airway prevents the patient from communicating verbally. 4. Family support a) The psychosocial needs of the patient’s family are important, while the patient physical needs being managed on the ventilator. PowerPoint Slides 1. Goals of nursing management: physiologic needs and psychosocial needs 2. Physiologic needs Promoting optimal oxygenation Treating impaired gas exchange Providing adequate ventilation Clearing and protecting the airway Supporting tissue perfusion Providing adequate nutrition 3. Psychosocial needs Anxiety Pain Communication Sleep pattern disturbance Communication and sensation Family support IX. Weaning the Patient from the Mechanical Ventilator 1. Patients being evaluated for weaning from a mechanical ventilator fall into three categories: a) Those whose removal is rapid when the reason for ventilation is resolved b) Those whose removal is slow and gradual c) Those who are unweanable and need long-term ventilator support A. Readiness for weaning 1. Traditional methods to determine readiness to wean a) Initial patient screening b) Comprehensive patient screening 2. Alternative indications of readiness to wean. a) Rapid shallow breathing index less than 60 to 105 breaths/min/L (spontaneous breathing) b) Vital capacity (VC) greater than 15 mL/kg c) Breathing rate (f) less than 35 spontaneous breaths/minute d) Spontaneous tidal volume (VT) greater than 4 to 6 mL/kg (IBW) e) Maximum inspiratory pressure (MIP) less than ?20 to ?30 cm H2O f) Minute ventilation (VE) less than 10 to 15 L/minute g) Airway occlusion pressure (P0.1 or P100) less than ?6 cm H2O B. The weaning process: Duration 1. Rapid weaning (short term): Patient is placed on T-piece for 30–120 minutes and may then be extubated if trial is successful. 2. Slow weaning (long term): difficult and complex process that can require use of many weaning alternatives, such as SIMV, mandatory minute ventilation, PSV, and manual weaning C. The weaning process: Methods 1. Manual Weaning is accomplished by following a schedule of disconnecting the patient from the mechanical ventilator for increasingly longer periods of time. 2. Ventilator Weaning is generally thought to be less traumatic for the patient because it does not involve intermittent removal from the ventilator. D. Special considerations for older adults 1. The elderly are at particular risk for developing complications of mechanical ventilation. a) No best method for weaning elderly patients has been identified. E. Postextubation follow-up 1. Extubation is carried out as soon as it is determined that the patient can sustain spontaneous breathing, usually indicated by maintaining their own airways and coughing adequately to mobilize secretions. 2. Terminal weaning a) Terminal weaning is the intentional removal of the mechanical ventilator when the patient is expected to die without it. b) The nurse closely monitors the patient’s status and provides PRN medications as needed. PowerPoint Slides 1. Categories of patients to wean Removal is rapid when the reason for ventilation is resolved. Removal is slow and gradual. Unweanable, and need long-term ventilator support. 2. Readiness to wean depends on the physiologic and psychological status of patient. 3. Bedside tests, a.k.a. AKA weaning parameters, can help assess patient’s readiness: Rapid shallow breathing index < 60 to 105 breaths/min/L (spontaneous breathing) VC > 15 mL/kg f < 35 spontaneous breaths/minute VT > 4–6 mL/kg (IBW) MIP < ?20?30 cm H2O VE < 10–15 L/minute Airway occlusion pressure (P0.1 or P100) < ?6 cm H2O 4. Weaning process Rapid/short-term Slow/long-term 5. Methods of weaning Manual Weaning Ventilator Weaning 6. After extubation, maintain pulmonary hygiene via: Coughing Deep breathing Spirometry X. Chapter Summary XI. Clinical Reasoning Checkpoint XII. Post-Test XIII. References Suggestions for Classroom Activities Ask students to explain the similarities and differences between CPAP and NIPPV. Ask students to specify which patients might benefit most from noninvasive mechanical ventilation Ask students to role-play demonstrating to a patient how to use a CPAP ventilator Ask students to describe the various complications that can arise from use of an artificial airway Develop a role-play scenario. Select three students to participate. The rest of the class will observe and critique the interaction. The selected student group will demonstrate communication with the patient who is receiving mechanical ventilation. Cast one student as the patient, another the significant other, and the last student will act as the nurse Ask students to review the role of the nurse when caring for the patient after extubation. Review the phenomena of oxygen toxicity. What are the signs and symptoms? What potential causes are associated with the disorder? What actions can the nurse perform in prevention of the disorder? Suggestions for Clinical Activities Observe patients on NIPPV and CPAP ventilation. Ask students to describe the complications that can result from use of an artificial airway. Assign students to patients who might require secretion suction. Help students to perform the procedure. During the postconference period, discuss the actions taken. What signs did the patient exhibit when suctioning was needed? What monitoring took place after the suction procedures? Wagner et al., Instructor’s Resource Manual for High-Acuity Nursing, 6th Edition ©2014 by Education, Inc.