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Intermittent Positive Pressure Breathing (IPPB)

Intermittent Positive Pressure Breathing (IPPB)

Definition

  • IPPB: Intermittent Positive Pressure Breathing is the application of inspiratory positive pressure to a spontaneously breathing patient as an intermittent or short-term therapeutic modality.
    • Created by running pressurized gas into a mouthpiece or mask.
    • Treatment ends when a pre-selected peak inspiratory pressure (PIP) is reached.
    • Patients with healthy lungs need significantly less pressure than those with decreased lung compliance.
    • Typically accompanied by a Small Volume Nebulizer (SVN) using sterile saline or bronchodilator to humidify the air during treatment.
    • The SVN is integrated in-line with the pressurized gas delivery.

IPPB Machines

  • Common IPPB machines include:
    • BirdMark 7
    • Bennett PR2
    • 314
    • MARK 10
    • pirator
    • WATE
    • BENNETT

How IPPB Works

  • The operation of IPPB consists of the following steps:
    • A driving pressure is set on the machine.
    • When the patient triggers the machine by decreasing pressure in the line during inhalation, gas flows down to the mouth and airways.
    • The exhalation port is shut by a mushroom valve during inhalation.
    • Gas is continuously sent to power the inline SVN during the treatment.
    • Once the preset PIP is reached, gas flow ceases immediately (Inspiratory phase cycles off).
    • The mushroom valve collapses, allowing gas to exit through the exhalation port.
    • Respiratory rate is limited to 6-8 breaths per minute (SMI - Slow, Deep Breath).

Physiological Effects of IPPB

  • Increased Mean Airway Pressure (MAP):

    • An increase in MAP and intrathoracic pressure occurs due to the application of positive pressure, which can decrease venous return.
    • Normal breathing creates a thoracic negative pressure of approximately (-5 ext{ to } -10 ext{ cmH2O}), which facilitates blood return to the heart.
    • High thoracic pressures from IPPB therapy can hamper venous return, decreasing cardiac output, symbolically represented as:
      ↑ PL = ↓ CO
    • Blood can back up into the head, causing increased intracranial pressure (ICP).

  • Decreased Work of Breathing (WOB):

    • Provides ventilatory assistance, reducing reliance on respiratory musculature and energy expenditure.
    • Increases tidal volume (VT) by approximately 3-4 times during the treatment.
    • Enhances ventilation distribution and gas exchange.
    • Facilitates secretion mobilization, promoting effective coughing through SMI.
    • Continuous monitoring of heart rate is crucial; if HR increases more than 20 bpm during treatment, discontinue therapy.

Goals for IPPB

  • The primary goals of IPPB therapy include:
    • Increase tidal volume (VT).
    • Improve and promote the cough mechanism.
    • Enhance ventilation distribution and reduce atelectasis.
    • Administer medications with improved distribution.
    • Enhance breath sounds, especially in lower lung bases.
    • Improve oxygenation and ensure favorable patient responses.

Indications for IPPB

  • Suitable for the following conditions:
    • Atelectasis unresponsive to alternative therapies (i.e., cough, deep breaths, incentive spirometry).
    • Poor cough leading to inability to clear airways.
    • Short-term non-invasive ventilatory support for hypercapnic patients.
    • Delivery of aerosolized drugs when SVN has failed for patients unable to take deep breaths.
    • Prevention or reduction of pulmonary edema.
    • Positive pressure can help push fluid back into pulmonary capillaries, thus enhancing VT and oxygenation, leading to improved cardiac activity.

Absolute Contraindications

  • The absolute contraindication for IPPB:
    • Untreated Pneumothorax: Any untreated pneumothorax poses a risk of becoming a tension pneumothorax as positive pressure may push more air into the chest from the airway.

Relative Contraindications

  • Considered relative contraindications include:

    • Unskilled practitioners.
    • ICP over 15 mmHg.
    • Hemodynamic instability.
    • Active hemoptysis or pulmonary hemorrhage; positive pressure could exacerbate bleeding.
    • Conditions predisposing to hemoptysis include:
    • Active untreated tuberculosis (TB).
    • Lung cancer and cystic fibrosis.
    • Recent lung surgery.
    • Tracheoesophageal (T-E) fistula, allowing air to escape into the chest or esophagus.

  • Additional considerations:

    • Recent esophageal surgery, as IPPB patients might swallow significant air, hampering recovery and potentially causing bleeding.
    • Recent facial, oral, or skull surgeries.
    • Symptoms like singultus (hiccups) or nausea due to air swallowing, leading to potential vomiting.
    • High pressures over 20 ext{ cmH2O} are associated with gastric distention.
    • Radiographic evidence of blebs or wheezing; IPPB may be administered with a bronchodilator if wheezing is present.

Hazards of IPPB

  • Identified hazards associated with IPPB therapy include:

    • Decreased cardiac output (CO) resulting from reduced venous return.
    • Increased airway resistance (RAW) particularly in patients sensitive to cooling airways.
    • Risk of barotrauma or pneumothorax in patients receiving excessive volumes and pressures or those who experience air trapping, notably in COPD patients.
    • Potential for blebs to rupture, leading to hemoptysis.
    • Air embolism caused by broken blood vessels allowing air into the bloodstream.
    • Nosocomial infections due to bacteria being sent deeper into the lungs.

  • Other potential hazards:

    • Hyperventilation leading to tingling fingers, lightheadedness, and alkalosis, potentially triggering cardiac arrhythmias.
    • Respiratory depression, particularly in chronic hypercapnic patients, as increased FiO2 may dull hypoxic drive.
    • Gastric insufflation/distention from swallowing air, potentially causing belching, discomfort, and vomiting.
    • Possible psychological dependence and secretion impaction due to inadequate humidity.

Assessment of Patient on IPPB

  • Pre-assessment steps include:

    • Evaluating the necessity for therapy and ensuring outcomes are measurable.
    • Considering alternatives such as incentive spirometry (IS), slow deep breaths (SMI), or EZ-PAP.
    • Reviewing patient history and x-rays for contraindications.
    • Assessing baseline vital signs, particularly heart rate: an increase due to machine pressure alone is normal, but continued increased HR could necessitate slowing the treatment and allowing longer intervals between breaths.
    • Respiratory rate (RR) should generally decrease post-treatment; if bronchospasm or barotrauma occurs, RR could increase.
    • Evaluating sensorium is crucial; in chronic hypercapnic patients, supplemental FiO2 may induce sleepiness and confusion.
    • Respiratory sounds, breathing patterns, and tidal volumes should also be measured.

  • After 5 minutes of treatment:

    • Re-assess vital signs, patient consciousness (sensorium), and returned tidal volume (VT).
    • Encourage the patient to cough and repeat assessments post-treatment to evaluate therapy effectiveness.

How to Measure Exhaled Volumes

  • Techniques for measuring exhaled volumes include:
    • Wright’s spirometer: Attach spirometer to exhalation valve and read the volume.
    • Venti-comp bag: Position the bag on the exhalation valve, count breaths needed to inflate the bag, then remove to gauge volume.

Administration of IPPB

  • Position the patient in a Semi-Fowler's position for treatment.

  • Ensure a tight seal around the mouthpiece.

  • Set sensitivity so that the patient can easily trigger a breath, typically between 1-2 cmH2O.

  • Establish adequate tidal volume (VT) by setting peak inspiratory pressure (PIP).

    • VT is contingent on selected PIP as well as patient lung compliance and airway resistance (RAW).
    • Aiming for a VT of 12-15 ext{ ml/kg IBW} (Ideal Body Weight) or at least 30 ext{%} of predicted inspiratory capacity (IC).
    • In cases of reduced lung compliance, PIP may need to be set as high as 30-35 ext{ cmH2O}.

  • Flow adjustments:

    • Increasing flow decreases inspiratory time (I-time); decreasing flow increases I-time.
    • Ideal I-time should be between 1-1.5 seconds; rapid flow rates can elevate compliance resistance (RAW).
    • Set expiratory time to be at least 3-4 times longer than inspiratory time, establishing an I:E ratio of 1:3 to 1:4.

  • Ensure appropriate respiratory rate (RR) of 6-8 breaths per minute; the patient may breathe faster off the IPPB.

  • Breathing Instructions:

    • Instruct the patient to inhale to cycle the ventilator, emphasizing relaxation during inspiration for proper lung filling.
    • At the end of inhalation, have the patient pause briefly before exhalation, which should be passive and effortless.
    • Advise the patient to count to three after exhalation before beginning the next inhalation to reduce RR.
    • Treatments generally last for 15-20 minutes.

IPPB - Initial Settings

  • Recommended initial settings include:
    • Sensitivity: -1 ext{ to } -2 ext{ cm H2O}
    • Initial Pressure: between 10 ext{ and } 15 ext{ cm H2O}
    • Breathing Pattern: usually set at 6 breaths/min.
    • I:E ratio around 1:3 to 1:4; adjustments to flow and pressures may be required as treatment progresses and patient needs are assessed.

IPPB - Monitoring and Troubleshooting

  • Monitor machine performance by checking:
    • Large negative pressure swings at the start of inspiration indicate incorrect sensitivity or triggering settings.
    • If system pressure drops post-inspiration initiation or fails to rise steadily, it may be necessary to increase flow until consistent pressure is achieved.
    • Excessive flow may cause the device to prematurely cycle off, along with kinks or occlusions in tubing or mouthpiece.
    • Identify leaks as they prevent preset pressures from being reached; differentiate between machine and patient interface leaks.
    • Nasal leaks can often be corrected with nose clips.

IPPB - Charting

  • Details to chart regarding therapy include:
    • Method of treatment administration (e.g., mouthpiece, mask, tracheotomy).
    • Pressure recorded in cmH2O.
    • Type of gas mix used (Air/mix or 100% O2).
    • Duration of treatment.
    • Patient positioning.
    • Positive End-Expiratory Pressure (PEEP) used in cmH2O (if applicable, a PEEP valve is often attached to the exhalation port).
    • Medications administered and their dosages.
    • Any observed adverse effects during treatment.
    • Vital signs and breath sounds post-therapy for further assessment.