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Clinical Indications and Goals for IPPB

Patients afflicted with diseases that limit the depth of breathing can be have their VT increased, sometimes as much as fourfold, with IPPB. The single overall clinical goal of IPPB therapy is to provide patients with a significantly larger VT at a physiologically advantageous inspiratory-to-expiratory pattern than the they can produce with spontaneous ventilation.

In the past, IPPB therapy was administered for a host of reasons, some well founded and others without any sound clinical or physiologic basis. Today, this shotgun approach to using IPPB is no longer acceptable. As discussed earlier, the use of IPPB must be supported by corroborating patient data that clearly indicates a potential benefit. Substantiated indications for IPPB include:

• To improve lung expansion: It is important that patients be able to breathe deeply so they can maintain an effective cough mechanism to facilitate removal of secretions from the airways. An effective cough maneuver involves taking a deep inspiration, the glottis closing, the diaphragm and other muscles of respiration contracting, and achievement of high interpulmonic pressure. The pressure is then strongly released causing the gas behind the secretions to move upward at high velocities carrying out the secretions. Patients unable to make these deep inspirations may need IPPB therapy may assist their efforts.
  
  IPPB can also be helpful for patients with atelectasis that has been unresponsive to other therapies. A correctly administered IPPB treatment can provide these patients with augmented tidal volumes, achieved with minimal effort.
  
  The optimal breathing pattern to reinflate collapsed lung units with IPPB consists of slow, deep breaths that are sustained or held at end-inspiration. This type of inspiratory maneuver increases the distribution of inspired gas to areas of the lung with low compliance, specifically, the atelectatic areas. While IPPB proven successful in treating atelectasis, there is little evidence of its prophylactic value in preventing the occurrence of this postoperative complication.

To provide short-term ventilatory support: Appropriately applied IPPB therapy improves the distribution of ventilation in patients with ventilation-perfusion mismatch, and has a great potential for decreasing the incidence of postoperative atelectasis and pneumonia. Patients who have to work hard to adequately ventilate themselves can benefit from IPPB therapy. With the equipment machine providing the force for ventilation rather than the patients, periods of positive pressure ventilation allow them to rest without losing adequate ventilation. Many of these types of patients are afflicted with chronic obstructive pulmonary disease (COPD) or some neuromuscular disease. If they can learn to cooperate with the therapy and not fight or lead the device, IPPB can help decrease their consumption of oxygen. IPPB is also a viable alternative to tracheal intubation and continuous mechanical ventilation for some patients with acute hypercapnic respiratory failure. Patients most likely to benefit are those with pre-existing COPD whose condition acutely worsens. Stabilization may require continuous treatment for several hours or more, but given the costliness and poor outcomes of long-term ventilatory support in these patients, early aggressive intervention with IPPB during an acute exacerbation of chronic lung disease represents a sound clinical decision.

• To aid in the delivery of aerosolized drugs: Administering medications via aerosol helps assure that they will be deposited deeper and more equally than other modes of delivery. IPPB helps provide a larger volume of inspired gas under higher pressures, dilates the airways and alveoli, bypassing obstructions, and provide an opportunity for more of the medication to be absorbed. This is particularly helpful in caring for patients unable to breathe deeply or who may not benefit from normal aerosol treatment. If IPPB is to be used to deliver aerosolized medications,the following should be observed:
  
  
  • Unless tracheal suction is also administered, mucolytics should not be delivered to the patients without ineffective cough unless tracheal suctioning is also ordered.
    
    
  • When an aerosol is delivered via a tracheostomy, the patient receives a higher concentration of the drug compared to administering the via a mask or mouth piece.
    
    
  While some physicians view IPPB therapy primarily as a means of delivering medications, it is generally considered an unjustifiable expense to use IPPB for this purpose when medication can be safely and conveniently delivered by other means (hand nebulizers, SVNs, MDIs, DPIs). The decision to use IPPB as an alternative method for giving aerosolized drugs should be based on clear evidence that the patient is unable to properly other delivery systems.

  Therapy that is expensive should be judged on its cost-effectiveness as well as clinical effectiveness. Whether administered to improve the cough, improve distribution of ventilation, or deliver medication, IPPB is justified only if the patient's ability to inspire adequately is limited. The clinical situations indicating a need for IPPB therapy include the following:

  • Clinical diagnosis of atelectasis
    
    
  • Reduced lung volumes, eg:
    

    Vital capacity <10-15 mL/kg
    Inspiratory capacity <40% predicted

    
    
  • Reduced expiratory flows (precluding effective cough), eg:
    

    FEV1 <65% predicted
    FVC <70% predicted
    

  • Neuromuscular disorders or kyphoscoliosis with associated decreases in lung volumes and capacities
    
    
  • Fatigue or muscle weakness with impending respiratory failure
    
    
  • Presence of acute severe bronchospasm or exacerbated COPD that fails to respond to other therapy