NON-INVASIVE VENTILATION WITH AVERAGE VOLUME-ASSURED PRESSURE SUPPORT FOR ACUTE HYPERCAPNIC RESPIRATORY FAILURE

Abstract

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Average volume-assured pressure support (AVAPS) is a comparatively newer modality of non-invasive ventilation that incorporates the properties of both volume and pressure-control ventilation. Though its benefits were well documented in chronic respiratory failure, studies illustrating its usage in acute respiratory failure are still insubstantial. Herein, we aim to showcase the utility of AVAPS in the management of acute on chronic hypercapnic respiratory failure. CASE PRESENTATION: An 80-year-old female with a body mass index (BMI) of 37 kg/m2 and chronic opiate use presented to the Emergency Department (ED) following a two-day history of increasing shortness of breath and confusion. Her medical history was notable for hypersensitivity pneumonitis secondary to bird exposure, former smoker, paroxysmal atrial fibrillation, and recent acute pericarditis for which she is taking aspirin and colchicine. An arterial blood gas (ABG) showed a pH of 7.14, PaCO2 of 124 mmHg (FiO2 28%), PaO2 of 94 mmHg, and bicarbonate of 41 mmol/L. A chest x-ray showed increased bilateral interstitial infiltrates. The patient received IV methylprednisolone and was placed on Spontaneous/Timed mode Bilevel positive airway pressure (BiPAP S/T) with an Inspiratory positive airway pressure (IPAP) of 10 mmHg, Expiratory positive airway pressure (EPAP) of 5 mmHg, and a respiratory rate of 12/min. At these set pressures, her inspired tidal volumes were around 400ml. The patient continued to remain confused (GCS 12/15) and thus, she was switched to average volume-assured pressure support (AVAPS) with a target tidal volume of 500ml. With this modality, she displayed rapid improvement in her symptoms and an ABG drawn eight hours after initiation revealed a pH of 7.34, PaO2 of 66 mmHg, PaO2 of 135 mmHg (FiO2 50%), and bicarbonate of 34 mmol/L. The patient was discharged home on the 5th day after admission. DISCUSSION: AVAPS is an intelligent modality of non-invasive pressure support that gives us the option to set a maximum and a minimum IPAP, in place of one fixed IPAP setting, along with a target tidal volume. The ventilator automatically adjusts the inspiratory pressure within the set range to ensure the delivery of pre-set tidal volume. Patient-ventilator dyssynchronization is prevented and previous studies have reported better patient comfort and satisfaction with AVAPS, thereby, improving patient compliance to the treatment. AVAPS was shown to be superior to BiPAP S/T and associated with a rapid improvement of ABG values and GCS score in patients with acute hypercapnic respiratory failure complicated with hypercapnic encephalopathy (GCS <10/15). CONCLUSIONS: Our case highlights the valuable utility of AVAPS and how, in certain clinical situations, it may be a preferred first-line modality over standard BiPAP S/T for the treatment of acute hypercapnic respiratory failure. REFERENCE #1: Yarrarapu SNS, Saunders H, Sanghavi D. Average Volume-Assured Pressure Support. 2021 Jan 5. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 32809435. DISCLOSURES: No relevant relationships by Pramod Guru, source=Web Response No relevant relationships by Devang Sanghavi, source=Web Response No relevant relationships by Hollie Saunders, source=Web Response No relevant relationships by Siva Naga Yarrarapu, source=Web Response