COVID19 AND HIGH FLOW OXYGEN THERAPY

COVID-19 disease constitutes a serious pandemic with viral pneumonia as the most common serious disease. It is caused by SARS-CoV-2, a betacoronavirus that is in the same subgenus as several bats, including the severe acute respiratory syndrome virus (SARS-CoV). The disease is manifested by a number of symptoms, up to profound hypoxemic respiratory failure.

What is Covid 19?

COVID-19 is a viral pneumonia that emerged in 2019 and reached Pandemic status by March.

The SARS-CoV-2 virus shares 79.6% sequence identity with SARS-CoV and reaches the cell using the same receptor, angiotensin, which is converted to enzyme II (ACE2).

According to the World Health Organization, COVID-19 is transmitted through fomites when there is unprotected contact between respiratory droplets and the infected person.

Airborne spread has not been reported and is not believed to be a significant driver of transmission based on the current situation. Fecal shedding has been demonstrated in some patients and live virus has been detected in a limited number of reports, but the fecal-oral route does not appear to be a factor for Covid-19 transmission.

Transmission of the Disease

• Droplet transmission
• Airborne spread has not been reported to date.
• Fecal-oral spread is possible but does not appear to be causative.

Symptoms and Signs

Very common Less common

-Fever (87%) -Sputum Production (33%)

– Cough – Shortness of breath (18%)

-Fatigue -Sore throat (13%)

-Myalgia (14%)

-tremors (11%)

-Nausea or vomiting (5%)

-Nasal congestion (4%)

– Diarrhea (3%)

Disease Severity & Prevalence

-Symptoms begin to appear 5-6 days after infection

-80% of cases are mild to moderate

– 13.8% cases severe

– 6.1% critical

First Mortality Rates in Intensive Care Units

-81%4

-97 %5

Current Mortality Rates (Armstrong et.al. meta-analysis6)

– 24 observational studies involving more than 10,000 patients

-Death trend in intensive care units decreased from 50% to 42%

Why Have Mortality Rates Dropped?

-Better treatment, more information and resources about the disease

-Trend is valid worldwide

-However, ICU mortality rates are high for Covid-19 compared to viral pneumonias

High Rate Nasal Insufflation Therapy

HVNI Working Mechanism

High Rate Nasal Insufflation (HVNI), High Flow Nasal Cannula (HFNC) have the same characteristics, both deliver heated humidified gas through an open nasal interface. both in this

It can deliver oxygen-rich gas in supraphysiological streams, allowing a precise FiO2 delivery in the treatment of hypoxic respiratory failure.

HVNI differs from HFNC in the ventilatory support it provides for spontaneously breathing patients.

The FDA has assigned a new product code to the Precision Flow Hi-VNI system, and the description for this code is ventilation support for spontaneously breathing patients.

The main mechanical difference between HFNC and HVNI is the flow rate of the gas introduced into the nose. The high velocity high flow facilitates the removal of post-expiratory CO2 between the extra thoracic dead space and breath, and during the expiratory phase of ventilation.

HVNI is an open interface, high flow oxygen delivery system.

High velocity gas creates complex vortices that facilitate rapid evacuation of dead space, a feature important for patients who are breathing very rapidly.

Other mechanisms of action of HVNI include delivery of warm and humidified gas into the airways to improve pulmonary compliance and maintenance of mucociliary function. Providing adequately heated and humidified gas reduces the metabolic workload. High Flow therapies (HFNC and HVNI) provide patients with adequate flow oxygenation support and reliable high FiO2 delivery.

Both appear to effectively manage the hypoxic respiratory system in adult patients presenting to the emergency department. Washing out the dead space is made very easy by the high velocity gas flow transmission mechanics of the HVNI interfaces. This allows for therapeutic treatment at lower volumetric flow rates.

Overall, High Flow therapy has shown ample capacity to manage acute respiratory failure. A meta-analysis including HFNC showed superior results in endotracheal intubation compared to conventional oxygen therapy.

HVNI is a potential therapeutic adjunct in the treatment of acute respiratory failure associated with COVID-19 viral pneumonia. The risk-benefit ratio of any respiratory therapy application that provides ventilation and oxygenation support to patients must be considered, including resource management issues. Clinical efficacy and probability of success, ease of use, simplicity of the interface, and known or suspected risks (including accidental contamination) should be considered when making clinical decisions.

As a result, the clinician responsible for the patient is responsible for maximizing the improvement of details including patient management, successful management of treatment, prudent use of clinical resources, and risk reduction, including patient, staff, and environment.

Shortly

COVID-19 may present with acute respiratory distress syndrome advanced from respiratory failure and (ARDS) pneumonia.

This phrase includes acute respiratory failure, typically Type I (hypoxic). This distress can be eliminated by providing the patient with HVNI humidified and heated oxygen, which allows spontaneous breathing and its use is carried out in accordance with international guidelines.

HVNI is associated with specific clinical and environmental advantages over other non-invasive ventilatory respiratory supports.

HVNI has been shown to be an effective tool for treating all causes of respiratory failure in adults.

COVID19 AND HIGH FLOW OXYGEN THERAPY