Venturi mask is the pioneer of High-Flow Oxygen Therapy Concepts
From Firenze University Press Journal: Infermieristica Journal
Matteo Manici, RN, MSN, Post-Operative Intensive Care Unit, University Hospital of Parma
Stefano Bambi, RN, MSN, PhD, Associate Professor, Health Sciences Department, University of Florence
Alberto Lucchini, RN, Head Nurse, General Intensive Care Unit, Emergency Department — ASST Monza — San Gerardo Hospital, University of Milano-Bicocca
Oxygen delivery is probably one the most frequently administered medication by nurses worldwide. Oxygen was discovered by Joseph Priestly in the late 18th century and has been used as a treatment for patients with acute and chronic respiratory failure until nowadays1. Its use should be carefully considered. Like any other medication, it may cause harm to patients if misused. In clinical practice, a common debate between two currents of thought has been going on until today: “you can’t administer too much oxygen” versus “oxygen won’t hurt”.
Recently healthcare professionals tended to titrate oxygen administration to avoid the side effects of both hypoxaemia and hypoxemia in emergency and intensive care settings field. Indeed, the risks related to hypoxaemia are widely known. On the contrary, complications related to excessive oxygenation seem to have a low priority for healthcare professionals. Oxygen can be administered through low “ow — delivering “pure” oxygen until 30 L/min — or mixed with ambient or compressed air providing high “ows from 30 to 80 L/min and over, using many different interfaces. Recently, Miller and colleagues have proposed Venturi mask is the pioneer of High-Flow Oxygen Therapy Concepts standardisation of High-Flow Oxygen Therapy Concepts. The authors organised the mess of the several terminology changes introduced with the extensive employment of oxygen therapy through high “ow nasal treatment during the last years. Many trade terms refer to those oxygen delivery modes. They include high-velocity nasal insu$ation (Hi-VNI — Vapotherm, Exeter, New Hampshire), high-”ow nasal insu$ation (HFNI), high-”ow nasal oxygenation, Opti”ow (Fisher and Paykel, Irvine, California), transnasal humidified rapid-insufflation ventilatory exchange, heated high-”ow nasal cannula, heated humidified high-”ow nasal cannula, and high-”ow nasal cannula.
HFN therapy provides optimal humidification and other benefits affecting physiologic mechanisms: physiological dead space washout with improved carbon dioxide (CO2) levels, decreased respiratory rate, positive end-expiratory pressure, increased tidal volume, and end-expiratory volume. The authors suggest High Flow Nasal Insufflation (HFNI) as a more appropriate terminology to better describe this mode of “noninvasive high-”ow respiratory support”.Unlike the conventional oxygen therapy modalities, HFNI can deliver heated and humidified gas with very high-”ow rates that can approximate the patients’ inspiratory demand while maintaining an adjustable oxygen inspiratory fraction (FiO2). If gas “ow rate exceeds their inspiratory peak “ow (PIF), patients can inhale a stable mix of air-oxygen “ow. Under normal conditions, PIF is about 20–30 l/min, and during increased effort or acute distress, spontaneous inspiratory until 45 litres per minute or greater !eld8,9. However, some doubts emerge because Miller and colleagues’ classification of 6 includes Venturi mask among low-”ow oxygen supports that do not meet inspiratory demand. Venturi Mask is a conventional oxygen therapy device developed about 1960 by Earl James Moran Campbell.
He applied to the medical !eld the Venturi effect — known since the late 18th century — creating an oxygen delivery face mask capable of administering an air/oxygen mix through high “ow rates and, at the same time simultaneously, preventing CO2 retention10. The Venturi face-mask face mask receives oxygen at a specific rate, “owing into the show through a narrow tube. The oxygen “ow rate increases by passing through the thin tube called the Venturi valve, and consequently, the downstream pressure decreases. The Venturi valve includes a side orifice that aspirates room air because of the decreased pressure within the lumen of the valve. In this fashion, the oxygen “ow is mixed with the room air before reaching the patient at a constant and predictable rate.
Product data sheets and many independent studies about the effectiveness of Venturi masks usually do not report data about the final “ow reached by this device. However, the basic concept of the Venturi mask developed by Campbell indicates that this system works as “air at a high “ow-rate with controlled oxygen enrichment” generating a “ow rate ranging from 30 to 80 L/min11. Flow rate performances can also vary according to the manufacturers’ characteristics of the Venturi valves. For example, in Intersurgical EcoLiteTM mask kits with a Venturi valve (Intersurgical LTD, UK), when the oxygen “ow through the Venturi valve is settled at 15 L/min with the FiO2 35% valve, delivers a total gas “ow of 84 L/min; the “ow decreases to 60 L/min with the FiO2 40%, and 30 L/min with the FiO2 60%.On these bases, we propose to maintain the Venturi Mask inside the conceptual framework of “high-”ow” oxygenation systems, especially when settled to a middle-low FiO2 setting (<50%), because FiO2 is inversely proportional to “ow. In addition, many Venturi systems are usually employed to generate high “ow rates to adequately supply to set up HFCI or Continuous Positive Airway Pressure (CPAP) devices (when a PEEP valve is added to the exit hub of an interface or an expiratory branch of a dual-limb breathing circuit.We hope that the COVID-19 world pandemic era could offer a way to rethink the education on oxygen therapy methods in academic and professional settings with the aim to perform a conscientious oxygen administration, titration and monitoring by nurses (and all the other healthcare professionals).
DOI: https://doi.org/10.36253/if-1668
Read Full Text: https://riviste.fupress.net/index.php/if/article/view/1668
