Airway Pressure Release Ventilation - Pulmonary Medicine - Lecture Slides, Slides of Pneumology

Download Airway Pressure Release Ventilation - Pulmonary Medicine - Lecture Slides and more Slides Pneumology in PDF only on Docsity!

Airway PressureRelease Ventilation

APRV

APRV zVentilator cycles between two differentlevels of CPAP – an upper pressure leveland a lower level zThe two levels are required to allow gasmove in and out of the lung zBaseline airway pressure is the upperCPAP level, and the pressure isintermittently “released” to a lower level,thus eliminating waste gas

APRV SET UP

APRV Settings zExpiratory time variable:

↓^ enough to prevent derecruitment &

↑enough to obtain a suitable TV (0.4 to 0.6 s) – Target TV (4-6ml/kg) zIf the TV is inadequate

→^ expiratory time is lengthened zIf TV too high (>6ml/kg)

→^ expiratory time is shortened

APRV Settings zThe inspiratory time is set at 4-6 seconds(the respiratory rate should be 8 to 12breaths per minute - never more) zI:E ratio: at least 8:1 and zTime at low pressure level should be brief(0.8 sec)

APRV Settings zNeuromuscular blockade should beavoided: the patient allowed to breathspontaneously (beneficial) zThe breaths can be supported withpressure support - but the plateaupressure should not exceed 30cmH2O

APRV Benefits zPreservation of spontaneous breathingand comfort with most spontaneousbreathing occurring at high CPAP z↓WOB z↓Barotrauma z↓Circulatory compromise zBetter V/Q matching

APRV Evidence zAPRV vs pressure controlled conventionalventilation patients with ALI after trauma (

n

= 30) zRandomized controlled, prospective trial z↓ICU days, ventilator days, better gasexchange, hemodynamic, lung comp, z↓Need for sedation and vasopressors

Varpula et al. Acta Anasthesiol Scand 2003

APRV Evidence zStock (1987) APRV vs. IPPV; dogs withALI (n = 10):

Better zRasanen (1988)

APRV vs. conventional ventilation vs. CPAP; anesthetized dogs (n= 10): Similar zMartin (1991)

APRV vs. CPAP vs. conventional ventilation :

Better zDavis (1993) APRV vs. SIMV; surgerypatients with ALI (n = 15) Similar

APRV zRathgeber (1997): APRV vs conventionalventilation vs. SIMV; patients after cardiacsurgery

(n = 596) zShorter duration of intubation: (10 hrs)than SIMV (15 hrs) or conventionalventilation (13 hrs) z↓Sedation&analgesia requirement zProspective, randomized, controlled, opentrial over 18 months, unevenrandomization

Mandatory Minute Ventilation zClosed loop ventilation: ventilator changesit’s output based on measured based on ameasured input variable zSpontaneous breaths: pressure control isused zIf anticipated V

< set (based on MV ofE^ past 30 sec): Mandatory breaths which areVC, time triggered

MMV zIn contrast to SIMV: MMV givesmandatory breaths only if spontaneousbreathing has fallen below a pre-selectedminimum ventilation