With regular inputs from Dr Monica Vasudev

Respiratory Care of The Nonintubated Patient

Specific aspects of respiratory care for deteriorating patients with COVID-19 before admission to the intensive care unit (ICU) include oxygenation with low flow and high-flow systems, noninvasive ventilation and the administration of nebulized medications.

How many will require oxygen

Data from Wuhan, China, has revealed that more than one-third of patients with COVID-19 infection (41.3%) will require oxygen and more than 1 in 20 (6.1%) will require mechanical ventilation. About 3.4% will develop acute respiratory distress syndrome (ARDS).

What should be ideal oxygen levels : SPO2 94-98%

The 2016 Oxygen-ICU randomized clinical trial revealed that there was an improvement in outcomes with a conservative oxygen strategy. It targeted a PaO2 of 70-100 mm Hg, or an arterial oxyhemoglobin saturation (SpO2) between 94% and 98%. The comparison group targeted a goal of an SpO2 of 97%-100%.

It was concluded that the conservative protocol led to decreased ICU mortality. The guidelines developed by an international panel of experts thus updated their oxygen targets. A 2018 systematic review and meta-analysis confirmed the benefits of a more conservative oxygen strategy.

What about other trials

In March 2020, two randomized clinical trials evaluating oxygen therapy were published in the New England Journal of Medicine. A large retrospective study was published in CHEST in late 2019. The studies assessed oxygen targets in the critically ill. While the first reported no difference in a conservative versus liberal approach, the second reported potential harm with the conservative approach. The third trial revealed that an oxygen saturation range of 94%-98% was optimal.

What is the current consensus

An oxygen saturation target as low as SpO2 88% seems to be contraindicated, especially in patients with moderate to severe ARDS.

We can limit SpO2 to below 96%. This seems safe and it may still prove to be beneficial.

What are the recommendations in COVID-19

Guidelines for the management of critically ill patients with COVID-19 have been issued. It has been recommended to start oxygen at an SpO2 of 90% and maintaining it no higher than 96%. This is a target of 90%-96%. Setting a lower limit of 92% provides a little breathing room.

What is Silent hypoxemia

It is being described in many COVID patients. The patient is very hypoxemic; they may have an oxygen saturation of about 85% on room air, but clinically they look comfortable. The patient may not be dyspneic or tachypneic and may not even verbalize a significant sense of shortness of breath.

It has been seen that patients sit there looking fairly normal, with a resting oxygen saturation much lower than what is expected for someone who doesnt have an underlying pulmonary disease or other symptoms.

What are the equipments required for escalation of O2 Therapy

Starting with patients with O2 sat <90%

Goal should be to maintain O2 sat > 90-96%

NC 1 – 6LPM + Surgical Mask

Venti Mask

NRB + NC

HFNC + Surgical Mask

NIV (i.e. CPAP)

If SPO2 < 90%

Low flow oxygen — For COVID-19 patients, it is appropriate to provide supplemental oxygenation with a low flow system via nasal cannula (up to 6 L/min). While the extent of micro-organism aerosolization at low flow rates is unknown, we can presume that it is minimal. So, start with nasal canula at 6 L/minute.

As demand increases, higher flows may be administered using a simple face mask, venturi face mask, or non-rebreather mask (up to 10 to 20 L/minute). As the flow increases, the risk of dispersion also increases, thus increasing the contamination of the surrounding environment and staff.

It has been suggested to have patients who wear nasal cannula wear a droplet mask (during transport to protect spread to the surrounding environment).

What if it fails

1. NPPV: FiO2 always at 100%, EPAP set to 5; Ensure the viral filter is connected, perform in negative pressure room
2. HFNC: FiO2 always at 100%, start at 20 L/mt, Goal SPO2 > 88%, Preferred over NPPV. This is for patients with higher oxygen requirements.

As patients progress, higher amounts of oxygen are needed. In non-COVID-19 patients, the options include high-flow oxygen via nasal cannulae (HFNC) or the initiation of noninvasive ventilation (NIVor NPPV). In retrospective cohorts, rates for HFNC use ranged from 14 to 63 percent while 11 to 56 percent were treated with NIV.

What next

Proning - buys time, change position every hour

What next

Intubate and transfer

When to transfer to ICU

For hospitalized patients who develop progressive symptoms, early admission to the ICU is prudent when feasible. The hospitalized patient spends as much time as is feasible and safe in a prone position while receiving oxygen.

What are oxygenation targets

The World Health Organization (WHO) suggests titrating oxygen to a target peripheral oxygen saturation (SpO2) of ≥90 percent.

For most critically ill patients, the lowest possible fraction of inspired oxygen (FiO2) necessary to meet oxygenation goals is preferred, ideally targeting a SpO2 90-96 percent, if feasible.

Which patients require lower targets of SPO2

Some patients may require a lower target. These include patients with a concomitant acute hypercapnic respiratory failure from chronic obstructive pulmonary disease (COPD). Others may warrant a higher target (eg, pregnancy).

NIV or intubation

In patients with COVID-19 with acute hypoxemic respiratory failure and higher oxygen needs than what low flow oxygen can provide, noninvasive modalities may be used selectively rather than proceeding directly to intubation, for instance, in a younger patient without comorbidities who can tolerate nasal cannulae.

Some patients may warrant avoidance of HFNC and may benefit from proceeding directly to early intubation, such as elderly or confused patient with comorbidities and several risk factors for progression.

Can we avoid both modalities HFNC or NIV and  proceed to early intubation if escalating beyond 6 L/min with continued hypoxemia or increased work of breathing

This is established on an increased risk of aerosolization and high odds that patients who need these modalities will rapidly deteriorate and require mechanical ventilation (eg, within one to three days). This approach may be reasonable when resources are available. However, using this as an absolute rule may cause excess of unnecessary intubations and place an undue load on ventilator demand as the disease surges.

This is particularly problematic for patients under investigation (eg, COVID-19 testing pending), patients who have chronic nocturnal NIV requirements, patients with chronic respiratory failure who have high baseline oxygen requirements, and patients with do-not-intubate status but who might benefit otherwise from NIV or HFNC.

What about Nebulized medications (spontaneously breathing patients)

Nebulizers are linked with aerosolization and potentially heighten the risk of SARS-CoV-2 transmission. In patients with suspected or documented COVID-19, nebulized bronchodilator therapy should be given for acute bronchospasm (eg, in the setting of asthma or chronic obstructive pulmonary disease [COPD] exacerbation). Otherwise, it should generally be avoided, particularly for indications without a clear evidence-base; however some uses (eg, hypertonic saline for cystic fibrosis) may need to be individualized.

What to use

Metered dose inhalers (MDIs) with spacer devices should be used instead of nebulizers for management of chronic conditions (eg, asthma or COPD controller therapy).

If nebulizer is necessary

If nebulized therapy has to be used, patients should be in an airborne infection isolation room, and healthcare workers should follow contact and airborne precautions with appropriate personal protection equipment (PPE), including N95 mask with goggles and face shield or equivalent (eg, powered air-purifying respirator [PAPR] mask]) as well as gloves and gown.

All non-essential personnel should leave the room during nebulization.

What needs to be avoided

• Positive airway devices for chronic nocturnal ventilation support
• Chest physical therapy or oscillatory devices
• Oral or airway suctioning
• Sputum induction to be avoided
• Bronchoscopy to be avoided in spontaneously breathing patients and limited to therapeutic indications (life-threatening hemoptysis, central airway stenosis)

If any of these therapies are performed, similar PPE to that described for nebulizer therapy should be used.

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA