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| LETTERS TO EDITOR |
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| Year : 2020 | Volume
: 64
| Issue : 12 | Page : 1085-1086 |
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Anti-fogging techniques as part of personal protective equipment (PPE)
Karthik Ganesh Ramamoorthy
Consultant in Anaesthesia, Fortis Malar Hospital, Chennai, Tamil Nadu, India
| Date of Submission | 05-Jun-2020 |
| Date of Decision | 29-Jun-2020 |
| Date of Acceptance | 25-Sep-2020 |
| Date of Web Publication | 12-Dec-2020 |
Correspondence Address:
Dr. Karthik Ganesh Ramamoorthy
Fortis Malar Hospital, Chennai, Tamil Nadu
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/ija.IJA_687_20
How to cite this article:
Ramamoorthy KG. Anti-fogging techniques as part of personal protective equipment (PPE). Indian J Anaesth 2020;64:1085-6 |
Fogging of protective head/eye gears is one of the most common problems in 80%[1] of cases in the daily practice of using PPEs during endotracheal intubation. Routine use of anti-fog treatment to prevent interference especially during airway management has been recommended.[2],[3] Full body encapsulating PPEs increase sweating and the added heat with moisture contributes to noncompliance in continued usage of PPEs.
Fogging of the eye PPE is caused mainly by two factors namely improper fit of the face mask causing escape of exhaled air from the upper edge of the mask and imbalance between temperature and humidity of the face relative to the environment.
While ensuring proper mask seal during donning by pressing down the nose piece, placing adhesive medical tape or double tape along the upper border and performing a “user seal check” essentially identifies air leak, this article highlights simple “Do It Yourself (DIY)” anti-fog techniques that could be attempted in health care settings.
The anti-fog agents are either hydrophilic agents or surfactant based. The commercially available hydrophilic anti-fog sprays being strong chemicals could irritate eyes and hence requires caution. Some DIY techniques are as below.
Iodophors[2] (e.g., povidone-iodine, a compound of polyvinylpyrrolidone with iodine) applied evenly on the inner layer of the protective glasses or shield with gauze, especially in the visual field area and used after drying, is an easily available measure. It is a proven disinfectant widely used in clinical practice with a good anti-fog effect but leaves a yellow tinge and needs time to dry. PVP or polyvinylpyrrolidone present in povidone-iodine is a hydrophilic synthetic polymer that readily dissolves water molecules.
A thin layer of Savlon antiseptic liquid (Cetrimide 3.0% w/v and Chlorhexidine gluconate 0.3% w/v) applied evenly on the inner layer of the goggles or face shield has an equally effective anti-fog effect. Cetrimide is a quaternary ammonium compound with surfactant and antiseptic properties[4]. Though routinely being used to demist nasal endoscopes and laparoscopic lenses, the residual Savlon needs to be wiped or allowed to air dry as it can cause eye discomfort. This technique is easier, quicker, and devoid of the yellow tinge associated with Iodophor.
The surfactant effect of detergents commonly used in daily life, such as dish soap,[2] baby shampoo, or hair conditioner is another easy way to defog. A small drop of detergent applied evenly to the inner layer and letting it dry before use prevents fogging.
Although hand sanitisers,[4],[5] (Chlorhexidine gluconate 0.5% w/v and Ethyl alcohol IP 70% v/v) have an anti-fog effect, the effect dissipates quickly over time (<20 sec) as the alcohol evaporates. It also has a mild irritant effect on inhalation and causes discomfort (as the alcohol content is as high as 70%).
Another handy method to reduce fogging is by increasing the face-mask distance[5] by keeping 5–6 cm between the forehead and the face shield. Most face shields having breathable foam in the forehead. A surgical Gamgee pad can be used for the face shields without the foam.
Another technique[6] has been described wherein the relative imbalance of temperature between the face and outside environment is altered. Nasal prongs are slipped snuggly underneath the foam of the face shield and placed over the forehead. Oxygen supplied through the nasal prongs at 10-12 L/min in the face – face shield space through flow meter from central supply or auxiliary oxygen port of anaesthetic machine achieves immediate defogging especially during critical events like intubation.
Anti-fogging with these techniques offers simple and effective means to avoid interference during airway management. Anti-fog preparations though easy, are to be planned early in the sequence of donning PPEs and should be a standard part of PPE in these testing times.[7]
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
 References | |  |
| 1. | Cook TM, El-Boghdadly K, McGuire B, Mc Narry AF, Patel Higgs A. Consensus guidelines for managing the airway in patients with COVID-19. Anaesthesia 2020;75:785-9.  |
| 2. | Yao W, Wang T, Jiang B, Gao F, Wang L, Zheng H, et al. Emergency tracheal intubation in 202 patients with COVID-19 in Wuhan, China: Lessons learnt and international expert recommendations. Br J Anaesth 2020;125:e28-37. |
| 3. | Patwa A, Shah A, Garg R, Divatia JV, Kundra P, Doctor JR, et al. All India difficult airway association (AIDAA) consensus guidelines for airway management in the operating room during the COVID-19 pandemic. Indian J Anaesth 2020;64:107-15. [Full text] |
| 4. | Luo M, Cao S, Wei L, Tang R, Hong S, Liu R, et al. Precautions for Intubating Patients with COVID-19. Anesthesiology 2020;132:1616-8. |
| 5. | Haj H AI and Khalaf F. Eliminating fogging in surgical visor masks. Bull Roy Coll Surg Engl 2016;98:164-7. |
| 6. | Singh HM, Bohra R, Singh RR, Almeida F. Prevention of fogging in face shield. A breath of fresh air: Defogging the face shield using nasal cannula with PPEs during COVID 19 pandemic. Newslett of Indian Soc Crit Care Med 2020;15.2:87. |
| 7. | Malhotra N, Joshi M, Datta R, Bajwa SJS, Mehdiratta L. Indian Society of Anaesthesiologists (ISA National) advisory and position statement regarding COVID-19. Indian J Anaesth 2020;64:259-63. [Full text] |
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