**4.4 COVID-19 pandemic**

The COVID-19 pandemic created a major challenge in airway management for both patients and providers [152]. It was reported that VL "should be dedicated for

#### **Figure 21.**

*Application of VS technique in a 42-year-old male patient (BMI 29.6 kg/m2 ) with cervical collar immobilization due to C4-5 contusion. (A) Fair mouth opening. (B) Copious saliva and secretions in the pharynx and larynx. (C, D) The immobilization process itself caused a worse glottic view (LQS scale: 2. No glottis structures can be seen at all). Fortunately, the space underneath the epiglottis is enough for passage of the stylet-ET tube. (E, F) The secretion bubbles disturbed the glottis view. The intubation time is 16 s. (Also see the Supplementary Materials Video S20).*

#### **Figure 22.**

*Application of VS technique in a patient undergoing stereotactic neurosurgery. This 59-year-old man with genetic torsion dystonia and Parkinson's disease (BMI 20.2 kg/m2 ) underwent frame-based stereotactic procedure for bilateral subthalamus nucleus electrodes implantation. (A) Prior to anesthesia induction, a head frame was mounted and secured. (B) Tracheal intubation was performed with VS technique. (C) Close-up views in front of epiglottis and glottis (D). Copious saliva and secretions were present. The intubation time is 14 s. (Also see the Supplementary Materials Video S21).*

use in patients with COVID-19, where this is feasible, and disposable VL blades are preferred" [153]. In reality, for practical reasons, DL was still used in certain cases during the COVID-19 pandemic [154–156].

At the very beginning of the outbreak of COVID-19, it was intuitive to use VL in the management of patients with COVID-19, both in emergent and non-emergent tracheal intubation [157–161]. On the other hand, the safety (transmission rate to the airway managers and team members) and efficacy (e.g., first-pass success rate, intubation time, complications) of VL and DL had not yet been validated in COVID-19 cases [162, 163].

When considering the factors (close proximity of operators and assistants to the patient airway, intubation speed, quality of airway view obtained, or degree of hypoxia during the tracheal intubation) it seems intuitive that VL would be superior to DL (if healthcare resource availability is not an issue). Because of extensive clinical experiences with VS, we applied that technique during the COVID-19 outbreak in Taiwan [65–70]. Since 2020, we have been hit by three outbreak waves (**Figure 23**, time points A, B, and C). From April 2022 to June 2022 22 cases called for tracheal intubation in the negatively pressurized isolation wards and 28 tracheal intubations for emergency surgeries in the negative pressure-operating room. All the tracheal intubations were accomplished with VS technique and a plastic shield (**Figures 24** and **25**). Because our staff (anesthesiologists and residents) are proficient in the use of VS technique (**Table 2**), it seems that COVID-19 intubations did not cause extraordinary mental loading, stress, or technical difficulties for the airway managers.

## **4.5 Rapid sequence intubation**

During the COVID-19 pandemic, it was recommended that PPE be worn by airway managers and airways should be secured in a rapid sequence induction (RSI) or modified RSI [154, 157, 159]. The intubation first-attempt and overall success rates were acceptable. It is inconclusive, however, that RSI itself consistently shows better clinical outcomes than not doing so [164–167]. Moreover, combined use of VL with RSI maneuver does not necessarily shows superiority over DL [168–171].

In our hands, the VS technique provided a higher first-attempt intubation success rate with RSI. The intubation time for VS was non-significantly shorter than DL [73]. Since the benefits of cricoid pressure (CP) is not conclusive, usually we conducted RSI without applying CP. It has been reported that BURP does not help, and jaw-thrust is the most effective maneuver to provide better laryngeal view and shorter intubation time [31]. **Figure 26** shows a tracheal intubation performed using VS technique under RSI protocol. **Figure 27** shows a similar RSI-intubation process in a confirmed COVID-19 positive patient undergoing emergency surgery. In both cases, the intubation process was smooth and swift, and the operators felt safe and better protected against virus exposure.

### **4.6 Double-lumen endobronchial tube**

The clinical role of VL on tracheal intubation with double-lumen endobronchial tube (DLEB tube) for thoracic surgeries has been reviewed [172, 173]. For tracheal intubation with double-lumen endobronchial tube, VL was found either to be superior or equivalent to DL [174–179]. When various outcome parameters were used as comparators (e.g., glottis view, time to intubate, first-pass success rate, complications, ease to use), different types of VL might exhibit their own advantages and

#### **Figure 23.**

*Application of VS technique to intubate patients at our institute during COVID pandemic in Taiwan. The inset photo (left) shows the operator equipped with PPE intubating with a C-MAC VS (Storz, Germany) in a mannequin simulation model. The inset photo (right) shows the real world when tracheal intubation was conducted with VS technique in an omicron-positive patient. Time point A: February 2020 [65]. Time point B: May 2021 [69]. Time point C: April 2022 [70].* X*-axis: The weekly report series number;* Y*-axis: The patient number. Green and blue colors indicate the surveillance reporting number and confirmed cases number, respectively. Data was modified from Taiwan CDC press release (https://www.cdc.gov.tw/En; data retrieved on July 20, 2022).*

#### **Figure 24.**

*Combined use of a piece of transparent plastic sheet and VS technique in a mannequin model (A) and in 52-yearold man during COVID-19 pandemic (B and C). The intubation time: 20 s. the detailed technique for this combination method can be seen in the reference [67]. (Also see the Supplementary Materials Video S22).*

#### **Figure 25.**

*Combined use of a plastic sheet barrier and VS technique in an omicron-positive patient undergoing emergency neurosurgery for intracerebral hemorrhage. This is a 77-year-old woman (BMI 23.2 kg/m2 ) with medical history of diabetes and brain tumor. The airway managers wore PPE and a piece of plastic sheet was used as a physical barrier against possible contamination from the patient's airway. The tracheal intubation was smoothly and swiftly achieved with VS technique. The intubation time is 10 s. (Also see the Supplementary Materials Video S23).*

#### **Figure 26.**

*Application of VS technique with rapid sequence intubation in a patient undergoing emergency abdominal surgery. This 57-year-old man (BMI 26.2 kg/m2 ) with medical history of duodenal adenocarcinoma (pT4N1) had received a Whipple operation 1 day prior to this emergency surgery. Acute abdominal distention, leukocytosis, and elevated C-reactive protein indicated an intra-abdominal infection. Acute abdominal distention, leukocytosis, and elevated C-reactive protein indicated intra-abdominal infection. Anesthesia induction was conducted using rapid sequence intubation with VS technique. Serial images of oropharynx and larynx (A–C) and glottis-vocal cordstrachea (D–F) are shown. A nasogastric tube is seen in (C). A. The intubation time is 5 s. (Also see the Supplementary Materials Video S24).*

#### **Figure 27.**

*Application of VS technique with modified rapid sequence intubation in a morbidly obese (BMI 53.3 kg/m2 , height 150 cm, weight 120 kg) COVID-positive patient undergoing emergency surgery. The intubation time is 7 s. (Also see the Supplementary Materials Video S25).*

shortcomings [178, 180]. Not surprisingly, VS technique was alternatively applied for double-lumen endobronchial tube insertion [90, 181, 182]. It was found that VS is quicker, easier, has better glottic visualization, less complications, and was a useful alternative airway tool for placement of DLEB tube. In our single-institute experience, the volume of video-assisted thoracic surgeries using double-lumen endobronchial tube (few using blockers) is about 100 a year. The VS technique has been routinely applied for double-lumen endobronchial tube intubation. **Figure 28** shows such a case. The intubating process is smooth, quick, and with a clear glottis visualization. It should be emphasized that the stick of the VS for DLEB tube intubation should be longer and thinner in order to cope with the design of the DLEB tube.

#### **4.7 Cardiopulmonary resuscitation**

It is still a matter of debate whether VL is superior to conventional DL for tracheal intubation during emergency or critical situations. It is generally believed that, if the study outcome parameters are glottis visualization and first-pass success rate, both airway modalities could be equivalent [183–190]. Various factors can come into play including experience, in-hospital/out-of-hospital or emergency room/ICU setting, normal/difficult airway, routine use/rescue alternative, etc. [44, 191–197]. The comparison between VL and DL has been widely conducted [7, 198–202]. Quite often, it was found that VL provides better glottis visualization but does not improve the firstattempt success rate (which is highly experience-dependent) [203]. It is a consensus that uninterrupted, high-quality chest compressions during CPR is crucial to patient outcomes. A "hands-off time" less than 5 s while securing the airway without interruptions of chest compressions during CPR is beneficial for maintaining vital organ perfusion. Meanwhile, during cardiac massage maneuver, it is crucial to avoid unrecognized esophageal intubation [204, 205]. The role of VS has been tested and trained in a mannequin model in the emergency department [206]. Our

#### **Figure 28.**

*Application of VS technique for placement of double-lumen endobronchial tube. This is a 71-year-old man (BMI 16.5 kg/m2 ) who underwent esophageal reconstruction due to esophageal cancer (after definitive concurrent chemoradiotherapy). Although the patient's neck is stiff due to radiation fibrosis, the intubation is 23 s. (Also see the Supplementary Materials Video S26).*

single-institute experience is that we always applied VS technique to rescue failed or difficult tracheal intubation in settings outside the operating rooms (e.g., ER, ICU, general wards, endoscopy room). **Figure 29** shows such an example in a 65-year-old man with terminal lung cancer. During the night shift, this patient was found in cardiac arrest and the night staff called code blue but failed to secure the airway after multiple attempts by non-anesthesiologists. Non-stop CPR was continued for 30 min before the anesthesiologist arrived. **Figure 29** shows the tracheal intubation with VS was completed in 6 s without interrupting the CPR course.
