CPAP- BIPAP

Sussan Soltani Mohammadi.MDAssistant professor

Shariati Hospital

Positive Airway Pressure Therapy:

Application of higher than ambient airway pressure during inspiration and/or

exhalation to improve respiratory function

Positive pressure applied during inspiration → PPV.

Positive pressure applied during exhalation → PEEP.

Positive pressure applied during spontaneous breathing to maintain an elevated baseline airway

pressure → CPAP

Difference between PEEP and CPAP:

PEEP → elevated baseline pressure during mechanical ventilation (during separate

mode).

CPAP → elevated baseline pressure during spontaneous

breathing.

BIPAP: Bilevel positive airway

pressure→ is an intermittent CPAP or CPAP with release

Occasionally described as Airway Pressure Release

Ventilation (APRV)

This mode was developed during the late 1980s using the principle of

CPAP.

Allow the clinician to set the two CPAP levels → pressure high at

inspiratory time and pressure low or release pressure at expiratory time

In BIPAP clinician set not only the pressure but also the time spent at

each level.Time high or inspiration and time

low or expiration.When the patient is breathimng

spontaneously, transition of pressure

from higher to lower → tidal movement of gas and subsequent

CO2 elimination.

The short expiratory time( time at the low pressure)

prevents complete exhalation and maintains

alveolar distention .

When PP is applied to the respiratory system

(continuously or at end

expiration) → physiologic

changes occur → cardio respiratory system.

Pulmonary effecta) Redistribution of extra vascular

water → improve oxygenation, lungs compliance and

vent/perfusion matching.b) ↑ FRC → increase volume of patent

alveoli at lower levels of PEEP and inflation of previously collapsed

alveoli → alveolar recruitment at higher levels of peep.

Cardiovascular effects↓CO by three mechanism:

1) ↓ venous return

2) RV dysfunction (ppv increase PVR → increase RV afterload)

3) ↑pulmonary pressure → ↑ RVEDV →left ward shift of interventricular septum →LV distensibility ↓

Technical application 1) Invasively:

• Endotracheal tube

• Tracheostomy tube

2) Non invasively:

• Mask:

Nasal, Oronasal, Full face mask

• Nasal pillow

The basic equipments required are:

1) Ventilator

2) Ventilator tubing

3) An interface connecting the system to the patient

CPAP:Commonly is delivered by a tight

fitting maskWith a continuous gas-flow rate (15-

30 lit/min at a specific FIO2)A reservoir bag, a one way valve, a

humidifier and an expiratory pressure valve

patients can not tolerate mask due to

claustrophobia aerophagia or

hemodynamic instability → endotracheal

intubation

Indications1) Respiratory insufficiency has

not yet progress to true respiratory failure with dyspnea , use of accessory muscle

2) Ph < 7.35 , PaCo2 > 45 mmHg , RR > 25

3)Treatment of atelectasis (especially postoperative)

4) Post extubation stridor: Immediately → reintubation

30 min or later → is the result of laryngeal edema → CPAP

5) Accelerate the weaning of ventilatory support

6)Exaxerbation of COPD ,asthma

7) Hypoventilation syndromes (obesity, obstructive sleep apnea syndrome)

8) Do not intubate patients (who have refused intubation)

9) Acute cause of respiratory insufficiency who require a short

period of ventilatory support until underlying problem can be treated

(pulmonary edema , ARDS , pneumonia , chest trauma ).

Contraindications1) Cardiopulmonary arrest or sever

hemodynamic instability ,life threatening dysrhythmia

2) Apnea or need for immediate intubation

3) Facial burns , trauma or surgery

4) Uncontrolled vomiting or sever GIB and need for airway protection (risk of aspiration)

5) Uncooperative patient (extreme anxiety)

6) Sever ill patient with multi organ dysfunction

Ventilators• Most studies have used pressure cycle

ventilator however volume-cycle ventilator has been used successfully.

• Patients tolerate P.C.Ventilator better.

• Risk of barotrauma and degree of air leak are less than with V.C.Ventilator.

• Types of ventilators have ranged from standard ICU type ventilator

to portable ones designed for CPAP or NIPPV.

• Use of portable pressure-cycle ventilator in ICU provides high

FIO2 levels and lack of alarm or monitors.

MonitoringFor leaks around the mask

Amount of ventilation , ABG (PaO2)

Physical exam of the patient for synchrony with mechanical

ventilation

patient comfort

Presence or absence of stress responses (tachycardia , tachypnea)

Degree of accessory muscle use at the bedside

Unsuccessful treatment

Rapid shallow breathing

Continues accessory muscle use

Paradoxical abdominal respiration

Successful treatment Conversion of rapid shallow

breathing →slower deeper pattern Exhaled tidal vol ≥ 5-6 ml/kg RR≤ 20 ↓CO2

Improvement of respiratory parameter usually occurs within the

first hours.

Factors necessitating intubation

1)Major factors:Respiratory arrestRespiratory pause with gasping or

reduced consciousnessAgitation requiring sedationBradycardia with ↓ consciousnessHemodynamic instability (SBP < 70)

2) Minor factors:

RR>35(or > than admission)

PH< 7.30 (or < than admission)

PaO2< 60 mmHg

Increasing encephalopathy

Presence of one major factor at any time or

two minor factors after 1 hour of NIV

should lead to intubation

ComplicationsPressure necrosis over the bridge of

the noseNasal ,sinus or ear pain at initiation

of NIPPV (start at low pressure and slowly rise it)

Nasal congestion and drynessOral dryness

Eye dryness and iritationPneumothorax (rare but may

occur at high pressure especially in bullous lung disease)

Aspiration especially with full face mask

Gastric insufflation(25% may need NG tube)