Mannual hyperinflation

manual hyperinflation is used physiotherapy treatment, it is done by Ambu bag. it helps in improvement of lung volumes and maintain oxygen saturation

1. Manual hyperinflation Dr.T.Sunil Kumar Assistant Professor

2. Manual hyperinflation 'Bagging' can be used as a technique to hand-ventilate a patient or during physiotherapy. When hand ventilating, normal tidal volumes are generally delivered, whereas to facilitate physiotherapy larger breaths or hyperinflations are necessary. Manual hyperinflation can be given either using a Water's bag circuit or an Ambu -bag. A greater range of volume is available with a Water's bag. For an adult a 2 or 3 litre Water's bag, connected to a flow of 10- 15 litres of oxygen is commonly used .

3. By altering the expiratory valve, volume and therefore inspiratory pressure can be manipulated . The use of a manometer acts as a guide to inflation pressures which are recommended to be less than 40cmH2O. If manual hyperinflation is indicated in a PEEP dependent patient; a PEEP valve must be used to maintain positive end-expiratory pressure during treatment

4. Indications • To aid removal of secretions • To aid reinflation of atelectatic segments • To assess lung compliance • To improve lung compliance.

5. Therapeutic effects of manual hyperinflation The most common technique used is a slow inspiration, and inspiratory hold followed by quick expiratory release. A prolonged inspiratory hold is contraindicated in a patient who is already hyperinflated (e.g. emphysema).

6. Slow deep inspiration: Recruits collateral ventilation thus promoting mobilization of secretions Enhances interdependence to aid re-expansion of atelectatic segments Improves gaseous exchange Assesses and potentially improves compliance.

7. Inspiratory hold (at full inspiration): Further utilizes collateral ventilation and interdependence as at higher volume; therefore maximizes pressure distribution. Fast expiratory release: Mimics a forced expiration (huff or cough) Stimulates a cough. Hand-held PEEP: By grasping and holding the end of a semi-filled bag throughout inspiration and expiration it is possible to maintain a low level of PEEP.

8. Hazards of manual hyperinflation Reduction in blood pressure. During manual hyperinflation the normal mechanism which 'sucks' the remaining blood from the inferior vena cava to the right atrium during negative pressure inspiration is lost. In addition, the positive pressure generated during manual hyperinflation increases intrathoracic pressure. Both mechanisms compromise venous return. The resultant effect could be a reduction in stroke volume and therefore a drop in blood pressure

9. This risk is potentially increased when using a PEEP valve, or during prolonged inspiratory holds. It should be noted that if a bolus of sedation is given before treatment, this may lower the blood pressure through vasodilatation . Considerations for physiotherapy If the blood pressure drops during treatment, smaller tidal breaths should be given. If the blood pressure remains compromised the patient should be put back onto the ventilator/ positioned appropriately and a medical review requested.

10. Reduced saturations. Oxygen saturations can be compromised by sputum plugging, collapse, pneumothorax, bronchospasm and V/Q mismatching. Considerations for physiotherapy Reassessment will highlight the cause. Intermediate measures such as increasing the FiO 2 can be used .

11. Raised intracranial pressure. The presence of increased levels of PaC02 in cerebral blood vessels may lead to vasodilatation. The resultant increased cerebral blood flow may increase ICP . Considerations for physiotherapy To prevent fluctuations in ICP during manual hyperinflation small fast breaths should be interspersed between hyperinflations.

12. Reduced respiratory drive. PaCO 2 levels may be reduced during effective treatment. This may reduce the patient's respiratory drive. Considerations for physiotherapy After finishing manual hyperinflation, the patient's spontaneous respiratory effort should be monitored.

13. Contraindications to manual hyperinflation Undrained pneumothorax (presence of patent intercostal drain - treat as normal) Potential bronchospasm Severe bronchospasm Gross cardiovascular instability inducing arrhythmias and hypovolemia Unexplained haemoptysis An absolute indication for treatment should be present before manual hyperinflation is used on patients requiring PEEP levels greater than 15 cmH20 plus maximal ventilatory support, or patients with high peak and mean inspiratory pressures.

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