Emergency Intubation of Critically Ill Covid-19 Patients Using Conventional Laryngoscope: a Descriptive Observational Study


 BackgroundVideo laryngoscopy is recommended for critically ill COVID-19 patients due to safety concerns and to avoid complications. It is not available in some places forcing the operator to rely on conventional laryngoscope. Intubations in critically ill COVID is challenging and may lead to adverse complications and this may be affected by the laryngoscope used. The aim of the study was to analyse predictors of difficult intubation, complexity of intubation and complications of using conventional laryngoscopy in emergency intubations of COVID- 19 patients.MethodsA prospective observational study was done in COVID Intensive care unit of Base Hospital- Teldeniya, Sri Lanka from 1st of January 2021 to August 2021. Data was collected using a performa filled by operator at the end of the intubation. Apart from demographic data and clinical parameters, data related to intubation including MACOCHA score which is a validated score predicting difficult intubation in ICU(3) and Intubation difficulty scale (IDS) which measures actual complexity of intubation(4) were collected. The complications related to intubation were also analysed.Results84 out of 91 emergency intubations were done using conventional laryngoscope. Out of them 50.72 % were male and 49.27% Were female. Mean age was 50.75 years. First pass success rate was 83.3%. 25% had MACOCHA score more than 3. Most patients scored on the desaturation component of the score. Despite this only 50 % of the predicted difficult intubations actually had major difficulty in intubation. The commonest complication was hypotension. 12 had suffered cardiac arrest, and 4 of them were fatal. Conclusions Intubation of Critically ill COVID-19 patients are challenging, but can be done successfully with conventional laryngoscope. However, one must prepare for complications including cardiac arrest.


Abstract Background
Video laryngoscopy is recommended for critically ill COVID-19 patients due to safety concerns and to avoid complications. It is not available in some places forcing the operator to rely on conventional laryngoscope. Intubations in critically ill COVID is challenging and may lead to adverse complications and this may be affected by the laryngoscope used. The aim of the study was to analyse predictors of di cult intubation, complexity of intubation and complications of using conventional laryngoscopy in emergency intubations of COVID-19 patients.

Methods
A prospective observational study was done in COVID Intensive care unit of Base Hospital-Teldeniya, Sri Lanka from 1 st of January 2021 to August 2021. Data was collected using a performa lled by operator at the end of the intubation. Apart from demographic data and clinical parameters, data related to intubation including MACOCHA score which is a validated score predicting di cult intubation in ICU (3) and Intubation di culty scale (IDS) which measures actual complexity of intubation (4) were collected.
The complications related to intubation were also analysed.
Results 84 out of 91 emergency intubations were done using conventional laryngoscope. Out of them 50.72 % were male and 49.27% Were female. Mean age was 50.75 years. First pass success rate was 83.3%. 25% had MACOCHA score more than 3. Most patients scored on the desaturation component of the score. Despite this only 50 % of the predicted di cult intubations actually had major di culty in intubation. The commonest complication was hypotension. 12 had suffered cardiac arrest, and 4 of them were fatal.

Conclusions
Intubation of Critically ill COVID-19 patients are challenging, but can be done successfully with conventional laryngoscope. However, one must prepare for complications including cardiac arrest.

Background
With the onset of COVID-19 pandemic in 2019, the Intensive care units around the world has experienced increasing number of ICU admissions of patient requiring invasive ventilation (1) . Due to the infective nature of the SARS-CoV-2 virus through aerosol generation, the intubation procedure was regarded as a high risk procedure. (2) Many guidelines exist providing safe instructions to intubate critically ill COVID-19 patients. Personnel protective equipment (PPE) were considered mandatory. In most institutions the intubations were done by the most experience person which ensures rapid intubation reducing the time of exposure to the aerosol generation. (3) In most institutions intubation of SARS-CoV-2 patients were done using video laryngoscope. This has shown to reduce the time required for intubation and hence the time of exposure to aerosols and has been regarded as the gold standard for intubating COVID-19 patients. (3,4) Most institutions have been purchasing video laryngoscope for this purpose. Video laryngoscope are expensive and during the time of pandemic they were not freely available. This was the fate of the ICUs in most third world countries.
In most institutes in Sri Lanka which were managing COVID-19 critically ill patients did not have video laryngoscopes. Intensive care unit of the Base hospital Teldeniya, which was a designated COVID-19 treatment centre for COVID-19 in the central region of the country did not have the video laryngoscopy facilities at the start of the ICU. All patients admitted to ICU were intubated using conventional laryngoscopes. The unit acquired a video laryngoscope after 5 months of the commencement. Despite adequate training the doctors preferred conventional laryngoscope over video laryngoscope to intubate those patients.
There are minimal data available on patients with COVID-19 who requires intubation in ICU. Furthermore, no literature available on intubation using conventional laryngoscope in this cohort. This study was designed to assess the cohort of patients who requires intubation with respect to prediction of di culty in intubation and presence of actual intubation when using conventional laryngoscope. The complications that occur during intubation were also assessed.

Methodology
This prospective observational study was approved by the Ethical review committee of the National Hospital-Kandy, Sri Lanka (Ref NHK/ERC/17/2021) The study was carried out in COVID designated Intensive care unit , Base Hospital Teldeniya of Sri Lanka from 1 st of January 2021 to 31 st of August 2021. The principle objective of this study was to objectively identify the problems and complications associated with intubation of COVID-19 patients using conventional laryngoscope. Alternatively rate of rst pass success and presence of actual di culty of intubation and intubation related complications were also analysed.

Intubation
Intubation procedure was protocol based and the procedure was done by the most experienced person in the shift. Most of the staff had experience more than 2 years in ICU and some of the doctors had anaesthesia experience. All con rmed cases of COVID-19 were intubated with full personal protective equipment with KN 95 masks and face shields.
Possibility of potential di cult intubation was assessed using the MACOCHA score which is a validated tool in predicting di cult intubation in ICU patients (5) . This was done during the preparation stage of the intubation. Each procedure of intubation was performed with short acting muscle relaxants except for ones done during unexpected cardiac arrests.
An intubation attempt was described as insertion of the laryngoscope into the oropharynx.
Preoxygenation was de ned as providing supplementary oxygen prior to administration of sedation and muscle relaxants. Failed tracheal intubations were de ned according to Di cult Airway Society (London, United Kingdom) guidelines as four or more attempts at intubation, the nal recorded airway device being a supraglottic airway device, or the need for emergency surgical airway. (6) Objective assessment of intubation di culty was done using Intubation di culty scale which is widely accepted in ICU set up. (7) Non-invasive ventilation was continued in patients who were already on NIV until intubation. Bag and mask ventilation was avoided. All attempts of endotracheal intubation were con rmed by capnography.

Data collection
The Performa which includes the technical details and clinical details related to intubation was lled by the person performing the intubation at the end of the procedure.

Statistical analysis
Continuous variables are reported as mean ± SD for normally or uniformly distributed data, or median (interquartile range) for data with skewed distributions. Categorical variables were summarized as number (%) and compared using a Pearson's chi-square test or two-tailed Fisher's exact test at a twosided signi cance level of 0.05.

Results
The intensive care unit had 202 patients with COVID -19 during the study period. Out of the 91 patients required emergency intubation and out of those 84 intubations were done using conventional laryngoscope. 14 patients had di cult intubations having Intubation di culty score more than 6. Rest of the 70 patient had rst pass success in intubation which accounts for 83.33%.
In the total intubation cohort 50.72 % were male and 49.27% Were females. Mean age was 50.75 years.
(SD 14.9). The demographic features were compared between the two groups; di cult intubation and non-di cult intubation groups. There were no signi cant difference in age, height and weight among the 2 groups. ( Table 1) . Although statistical signi cance was not evident, male gender had a tendency for di cult intubation compared to females. Also doing the intubation in out of hours did not have any impact on di culty of intubation Emergency intubations in COVID ICU were performed due to many reasons. In our intensive care unit, the commonest cause was hypoxic respiratory failure which accounts for 60% of intubations. Out of these patients 10% had hypercapnia at the time of intubation. The reasons for intubations are illustrated in gure 1.
Intubation di culty was predicted using MACOCHA score in each patient. MACOCHA score is a validated scoring system to predict di cult intubations in ICU patients. Table 2 shows the percentage of patients who had a positive value for each component of the MACOCHA score. There were number of complications that occur at the time of intubation. The commonest complication was hypotension. 12 had suffered cardiac arrest, and 4 of them were fatal accounting for 4.7% of patients dying at the time of intubation. Figure 2 shows complications associated with intubations.
Only one intensive care doctor contracted SARS-CoV-2 infection during this period. The said doctor also had an outside contact source.

Discussion
Intubation is one of the commonest procedures carried out in Intensive care units. (8) In non-COVID patients, complications related to tracheal intubation can occur upto 40% of patients requiring intubation. (9) Therefore it is regarded as a high risk procedure. To add to this risk , in COVID-19 patients , intubation is regarded as an aerosol generating procedure and possess a risk for the person handling the airway.
Therefore , personal protective equipment (PPE) are considered essential.
Videolaryngoscopy is the commonly used modality in intubating patients with COVID-19. There are several advantages of using video laryngoscopy in COVID-19 patients. It has shown to increase the rst pass success, increase mouth to mouth to mouth distance and also has shown to improve visibility when wearing PPE. (10,11) Increase mouth to mouth distance allows having drapes and intubation boxes over patient's face. (10,11) For various reasons, some institutes use conventional laryngoscope for intubation. This is an expensive piece of equipment and therefore most of the institute in third world countries did not have enough number. At the same time the demand for the videolaryngoscopes were increased during the time of pandemic causing it limited in supply. Video laryngoscopy is a procedure which needs adequate training to perform. Most of the studies done among novice trainees in anaesthesia have shown that the skill of videolaryngoscopy is easy to acquire when compared to direct laryngoscopy. (12,13) Therefore it should be an easy skill to master among the experienced anaesthetists.
In our set up, the unit did not have a video laryngoscopy at the beginning of the pandemic. Therefore all intubations were performed using a conventional laryngoscope. Even when the video laryngoscope was available, the ICU doctors did not prefer it over a conventional laryngoscope and therefore majority of intubations were done with conventional laryngoscope. This problem is not uncommon. According to the survey done in UK by Cook and Kelly 92% of the hospitals that were included in the study had access to video laryngoscopy, but only 1/3 of them were actually using them regularly. (14) This attitude is expected to change after the pandemic as most institute are equipped with video laryngoscope.
Critically ill patients require intubation due to several reasons. In this cohort the commonest cause was hypoxic respiratory failure. Several studies have shown this as the commonest reason needing intubation in COVID-19 patients. (15,16) The experience from other COVID ICUs have shown that the patients could be extremely hypoxaemic due to rapid deterioration. Rapid deterioration it self will make the intubation challenging and di cult in this population. In addition, considerable amount of patients had CO2 retention in addition to hypoxia indicating a ventilatory problem as well. Considerable amount of patients had unexpected cardiac arrests requiring intubation. This may be higher than that of non-COVID patients, but further studies are needed.
MACOCHA score has been used in ICU patients in predicting di cult intubation. It had been validated in various critical care set ups. In MACOCHA score, desaturation more than 80% carries a high risk and 2 marks are allocated. In our cohort, most patients were scoring on the desaturation part of the score. SARS-CoV-2 mainly affect respiratory system and therefore these patients have more tendency to desaturation. That makes them to have a higher MACOCHA score with a possibility of di cult intubation. In our study out if the predicted di cult intubations only 50% of patients actually had di cult intubation.
Therefore there may be other factors come into play when intubation is considered in this cohort. Therefore further studies with a higher number of patients are required to validate MACOCHA score in COVID-19 critically ill population.
Many studies have shown that hypotension is the commonest complication that may arise during the time of ICU intubation in non-COVID patients (17,18) . This was similar in our cohort and hypotension was the commonest. 12 had cardiac arrest during intubation. In non-COVID population this is as low as 1.5-4%. (19) This is a very low value compared to 14.2% of cardiac arrests that occur at the time of intubation in this cohort. Most of the patients who requires intubation has severe disease and tends to suffer from other complications like myocardial ischaemia and acute kidney injury. Therefore the cause for cardiac arrest could be multi factorial. Out of 12cardiac arrests 4 were fatal.
The study mainly focus on laryngoscopy that are performed with conventional laryngoscope. There are no comprehensive analysis of complications that occur during conventional or video laryngoscopy in SARS-CoV-2 patients. This study will add to the literature as one of such studies.

Conclusion
Intubation is a high risk procedure carried out in ICU. Several methods can use to predict di cult intubation in critically and MACOCHA score is one of them. The score needs further testing in COVID-19 population. Intubation of Critically ill COVID-19 patients are challenging, but can be done successfully with conventional laryngoscope. However, one must prepare for complications including cardiac arrest. The staff should be encourage to use video laryngoscope and change of attitudes are necessary in this remark.

Figure 2
Complications during intubation