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Chapter 45 Noninvasive Ventilation

Chapter 45 Noninvasive Ventilation. Learning Objectives. Discuss the concept of noninvasive ventilation (NIV). List the goals of and indications for NIV. Select patients who should be managed with NIV. List those factors that are predictive of success during NIV. Learning Objectives (cont.).

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Chapter 45 Noninvasive Ventilation

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  1. Chapter 45Noninvasive Ventilation

  2. Learning Objectives Discuss the concept of noninvasive ventilation (NIV). List the goals of and indications for NIV. Select patients who should be managed with NIV. List those factors that are predictive of success during NIV.

  3. Learning Objectives (cont.) Discuss patient interfaces, types of ventilators, and modes of ventilation used during NIV. Discuss the initiation and management of NIV in the acute care setting. List and discuss complications associated with NIV and their possible solutions. Discuss the appropriate approach to the initial application of NIV.

  4. Introduction to Noninvasive Ventilation Abbreviated NPPV, NIPPV, or NIV Supports ventilation without artificial airway bag-mask provides the earliest example Encompasses both ventilation and CPAP Typically provided by nasal or oral mask

  5. Introduction to Noninvasive Ventilation (cont.) Use has increased due to: Improved patient interfaces Improved quality of NIV ventilators NIV software available for critical care ventilators Reports of success in literature

  6. Types of Noninvasive Ventilation Can be provided by a number of mechanisms Pneumobelt Rubber bladder strapped to abdomen Bladder filling compresses abdominal contents pushing up diaphragm causing exhalation Bladder deflation causes diaphragm to fall and inhalation occurs Some patients prefer this while in wheelchair

  7. Pneumobelt

  8. Negative-pressure ventilators (NPV) Negative pressure around thorax causes pressure gradient across chest wall – inspiration occurs Iron lung: widely for polio epidemic (1920-1960s) Surrounds entire body Porta lung is a simplified, cheaper version Chest cuirass: seals around the chest NPV fell from use with development of positive-pressure ventilation Types of Noninvasive Ventilation

  9. Noninvasive Ventilators

  10. Types of Noninvasive Ventilation (cont.)

  11. All of the following are goals for noninvasive ventilation, except? • Avoid Intubation • Improve mortality • Maximize patient comfort • Airway protection

  12. Acute Care: COPD Hypercapnic respiratory failure due to COPD is primary indication for NIV Strong evidence of efficacy in reducing Need for intubation Hospital mortality and length of stay Complications Standard of care for managing an acute exacerbation of COPD First-line therapy

  13. Acute Care: Asthma & Cardiogenic Pulmonary Edema Asthma and NIV Some evidence of positive results Improved P/F ratio, PaCO2, and pH Reduction intubation rates Use remains controversial Acute cardiogenic pulmonary edema: Numerous studies show power of CPAP CPAP first-line therapy NIV reserved for those with ventilatory failure

  14. Acute Care: CAP & Hypoxemic Respiratory Failure CAP and NIV Only improves outcomes with COPD patients who develop pneumonia Hypoxemic respiratory failure (P/F < 300) First-line therapy for immunocompromised, awaiting transplant, and post lung resection NIV very controversial for all other groups If used, note marked improvement in 1 to 2 hours or accept failure and intubate. 60% mortality noted if intubation is further delayed

  15. Acute Care: Other Indications for NIV DNI patients (do not intubate) Only use if it makes patient more comfortable or to manage a reversible disorder Postoperative use shows promise Some evidence CPAP post abdominal surgery improves outcomes NIV to facilitate weaning Reserve for COPD and CHF patients For other patient groups, NIV instead of reintubation worsened outcomes

  16. Noninvasive ventilation may be used for a patient with a DNI (do not intubate) order, in all of the following situations, except: • Make patient more comfortable • Patient refuses artificial ventilation • Managing a reversible disorder • Manage obstructive sleep apnea

  17. Chronic Care:Restrictive Thoracic Diseases Indicated for patients: post polio, NMD, chest wall deformities, spinal injuries, and severe kyphoscoliosis If evidence of nocturnal hypoventilation Hypersomnolence, morning headache, fatigue, dyspnea, cognitive dysfunction If present, use NIV to prevent chronic hypercapnia and associated hypoxemia Helps by resting muscles, lowering CO2, and improved compliance, FRC, and deadspace

  18. Chronic Care of COPD Patients Use is controversial Consensus conference recommendation Use for severe COPD with symptoms of nocturnal hypoventilation and one of the following PaCO2 > 55 mm Hg PaCO2 50 to 54 mm Hg with nocturnal desaturation Two hospital admissions for ventilatory failure

  19. Hypoventilation Associated with a number of diseases including central and obstructive sleep apnea and lung parenchymal diseases Nasal CPAP is first-line therapy NIV is recommended when other first-line therapies failed to alleviate hypoventilation

  20. Patient Selection & Exclusion & Predictors of Success: NIV Selection is generally established by signs and symptoms of respiratory distress (see Box 45-3). Exclusion occurs once the need for ventilatory assistance has been established (see Box 45-4). Predictors of success Summarized in Box 45-5 but generally patients are not as sick and/or respond rapidly to NIV

  21. All of the following are selection criteria for NIV patients in respiratory failure, except: • Excessive use of accessory muscles • Respiratory rate <25 breaths/min • Paradoxical breathing • Dyspnea

  22. NIV Equipment: Patient Interfaces Most common types Nasal mask Full-face mask (nasal-oral) Mouthpiece Less common Total face mask (covers whole face) Nasal pillows helmet

  23. Face Masks

  24. Nasal Pillows

  25. Patient Interfaces: Nasal Masks Triangular in shape, only covers the nose Made of hard, clear plastic with a cushion below for contact with face A strap assembly holds mask on face. Do not overtighten as may cause tissue necrosis

  26. Nasal Masks

  27. Patient Interfaces: Nasal Masks (cont.) Proper sizing Reduces incidence of pressure sores and tissue necrosis Reduces leaks Increases patient comfort Improves likelihood of long-term patient tolerance

  28. Nasal Masks

  29. Patient Interfaces: Full-Face Masks Interface of choice for patients with acute respiratory failure >90% of this group should start with full-face mask Designed for either Noninvasive ventilators: entrainment valve that prevents asphyxia if ventilator fails ICU ventilators: entrainment valve absent

  30. Patient Interfaces: Full-Face Masks (cont.) Disadvantages compared to nasal mask: Increased deadspace, claustrophobia, risk of aspiration Harder to talk and expectorate

  31. Full Face Mask

  32. Noninvasive Ventilators Most are electrically powered, blower driven, microprocessor controlled Designed to work with small leak and compensate for that leak Advantage: Patient ability to trigger and cycle properly in face of small to moderate leaks Internal oxygen blender is desirable but often absent hard to obtain >0.5 FIO2

  33. Noninvasive Ventilators

  34. Noninvasive Ventilators (cont.) Typical modes CPAP Pressure support (PSV) Pressure assist/control (P-A/C) With PSV and P-A/C, machine is patient or time triggered, pressure limited, and flow or time cycled Generate lower rates, pressures, and flows than ICU ventilators

  35. Noninvasive Ventilators

  36. All of the following are types of NIV modes, except: • CPAP • PSV • PRVC • P-A/C

  37. Critical Care Ventilators Much more sophisticated, allow for precise oxygen control, high flows, pressures, etc Inability to compensate for leaks is common Often results in triggering and cycling issues PSV breaths end at set percent peak flow; if flow does not fall to set percent, may lock in inspiration Modern vents can adjust cycle off percent Time-cycling solves problem and improves patient comfort Often causes lots of nuisance alarms Use full-face mask to minimize leaks

  38. Critical Care Ventilators CPAP, PSV, and P-A/C have all have been used. VC modes used but not recommended Leaks can lead to hypoventilation Various NIV packages now available on ICU ventilators; some will Compensate for leaks Allow audio alarm deactivation Set maximum inspiratory time (great option) No proven advantage of any mode

  39. Critical Care Ventilators

  40. Humidification Patients with symptoms of sneezing, nasal draining, nasal and oral dryness, and/or nasal obstruction benefit from humidity therapy Heated humidity relieves many of above symptoms, thus improving patient compliance Heat to about 30º C (patient comfort level). As length of use is unpredictable, recommend use of humidification for all patients receiving NIV

  41. Identifying Success or Failure of NIV Success easy to identify Improved ABGs: PaCO2 decreases, pH increases, PaO2 increases Clinical improvement: decreased RR, VT increased, diminished accessory muscle use Failure If in 1 to 2 hours the above are not noted; move to intubation Waiting too long can result in cardiac arrest

  42. Adjusting NIV Adjustments determined by patient presentation and ABGs High PaCO2: Increase pressure (VT) or rate Low PaCO2: Decrease pressure (VT) or rate Often rate is for backup only; if set in A/C may have above effects, but patient inspiratory efforts override ventilator setting High PaO2: Decrease oxygen or PEEP Low PaO2: Increase oxygen or PEEP When PEEP is adjusted, may alter pressure gradient and thus VT

  43. Monitoring NIV Must assess for Leaks Accessory muscle use Ventilator synchrony and patient comfort Improved vital signs and ABGs If patient worsens on optimal setting, think immediate intubation Particular attention must be paid to those with respiratory failure

  44. Adverse Effects & Complications of NIV Causes of NPPV failure include: Mask-related problems Flow-related problems Large air leaks Patientventilator asynchrony Lack of improvement in gas exchange See Table 45-2. Major complications: aspiration, hypotension, and pneumothorax

  45. All of the following are types problems which may occur with NIV, except: • Mask-related problems • Flow-related problems • Large air leaks • Improvement in gas exchange

  46. Time and Costs of NIV Success of NPPV is closely tied to time-intensive involvement of RT staff for Mask fitting Application Adjustment of NIV settings Patient education Following initiation, time required (costs, also) should fall to reflect those required for invasive ventilation

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