**6. Non-invasive methods of ventilation in aerosol generating procedure**

#### **6.1 Nasal cannula**

It is well known today that use of full PPE reduces the risk of infection in corona virus family [15], Based on retrospective study published on March 2020, hospital acquired infection was 41.3% from those 29% were health care workers from dif-

**OBESE Description**

**B** Bearded **E** Edentulous **S** Snoring

**O** Obese (BMI >26 kg/m2)

**E** Elderly (>55 years)

Level 3 (enhanced) is recommended in COVID 19 suspected or confirmed cases airway management for better understanding it is worth to mention here in summary what are the level of PERSONAL protection for healthcare workers [17]

The person who is performing the intubation should wear a third pair of gloves

Minimizing number of people during intubation is preferred in order to reduce risk of exposure. The interval time after intubation should be taken into consideration. The required waiting period will vary between 15 and 30 minutes [19].

• Fluid-resistant Type IIR surgical face mask and goggle or visor

• Filtering face piece 3 (FFP3) respirator and eye protection

• Disposable fluid-resistant hood (if wearing a gown without an attached

• 2 sets of long or extended cuff non-sterile, non-latex disposable gloves

• Reinforced fluid-resistant long-sleeved surgical gown

*Levels of personal protective equipment (PPE) for healthcare workers when providing patient care. (copied from health protection Scotland, "levels of personal protective equipment (PPE) for ward patient care").*

and remove them immediately after intubation [18].

**Level 1 SICPs Standard Infection Control Precaution** • Disposable apron • Disposable gloves

• Disposable gloves **Level 2 DROPLET DROPLET (RESPIRATORY) PRECAUTIONS** • Fluid-resistant disposable gown

• Disposable gloves

• disposable gloves

hood)

**Level 2 AIRBORNE AIRBORNE (RESPIRATORY) PRECAUTIONS** • Fluid resistant disposable gown

or a powered hood respirator

• Full length disposable plastic apron • FFP3 respirator or powered hood respirator

• Surgical wellington boots or closed shoes

**ENHANCED PRECAUTIONS**

• Disposable full-face visor

• Disposable boot covers

**Level 2 CONTACT DIRECT/INDIRECT CONTACT PRECAUTIONS** • Fluid-resistant disposable gown

*Shows OBESE mnemonics for difficult mask ventilation.*

*Special Considerations in Human Airway Management*

ferent specialties [16].

**(Table 5).**

**Level 3 ENHANCED**

**Table 5.**

**6**

**Table 4.**

Low-flow nasal oxygen (nasal cannula) may provide some oxygenation during apnoea (apnoeic oxygenation) and might therefore delay or reduce the extent of hypoxemia during tracheal intubation [21] however, literature suggests this beneficial effect might be worthless in patients with primary respiratory failure like in COVID 19 patients [22]. Till now, there is no evidence that low flow nasal canula can generate aerosols, in COVID 19 patients so, it is not recommended to use it routinely during intubation [23].

#### *6.1.1 High flow nasal cannula*

Using high flow nasal cannula (HFNC) 30–70 L/min significantly increases the risk of spreading exhaled gas [24], debate around using HFNC in COVID 19 considering it prolong apnoea time remarkably however there is few predisposed disadvantage: when used in deteriorating patients it is delaying intubation in severely ill patients who really need intubation, exhausting hospital oxygen reserves as a results in very high demand [25], when used during intubation risk of generating aerosol that carrying the virus [26].

**Important note:** after a few hours of ventilation by high flow nasal cannula (HFNC), the oropharyngeal airway and trachea become extremely dry, due to a high oxygen flow reaching 60 L/min. Which leads to difficulty in passing the endotracheal tube (ETT). So, make sure that the tube and the intubation equipment are very well lubricated to allow the tube to go easily through the vocal cords. Our personal experience is to soak the pharyngeal cavity with 10 ml 0.9% saline and some gel to allow a sufficient lubrication for this purpose.

#### *6.1.2 Non-invasive ventilation*

Data regarding use of non-invasive ventilation (NIV) in COVID 19 patients is limited but based on recent systematic review published recently the evidence for using NIV in COVID 19 patient is currently low in quality however it might reduce mortality and increase risk of healthcare worker transmission [27]. Many centres recommend to use NIV in view of limited resources in pandemic regions or using hyperbaric oxygen therapy in preventing mechanical ventilation in COVID-19 in other centers [28–30].
