This was a multicentre, retrospective observational study conducted at three non-academic rural hospitals in Jönköping County in southern Sweden.
Patient selection and methods
The study included all adult patients (> 18 years old) who were admitted to the ICU in Jönköping County between 14 March 2020 and 13 March, 2021 (Fig. 1). All included patients were diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, as confirmed by positive polymerase chain reaction results using nasopharyngeal swabs. The final date for data cut-off was 14 April 2021. Patients who were treated in the ICU in Jönköping County but underwent tracheostomy elsewhere were excluded. For patients transferred from our hospitals to different regions after receiving tracheostomy, data were collected only for the time in Jönköping County.
Patients who underwent tracheostomy were categorised into two groups based on the timing of the procedure. Those who were on mechanical ventilation for < 7 days prior to surgery were included in the “early” group and those who were on mechanical ventilation for > 7 days were included in the “late” group.
Medical records from Cosmic™ and MetaVision™ were reviewed retrospectively by trained abstractors to ensure accuracy.
Main outcomes and measures
Patient demographics included age, sex, body mass index (BMI), presence of comorbidities (cardiac disease, hypertension, diabetes, kidney/liver/lung disease, immunosuppression, neuromuscular disease, and active or previous cancer), as well as present or previous smoking habits and blood group. The primary outcome was the duration of IMV. The secondary outcomes included number of days on IMV prior to tracheostomy, time of decannulation, number of hours on mechanical ventilation in the prone position, ICU length of stay, all-cause mortality (within 30 days of ICU admission), and complications associated with tracheostomy (haemorrhage, aspiration, displaced tracheal cannula, tracheal injury, failed surgery, accidental decannulation, stoma infection, perioperative hypoxemia, pneumothorax/pneumomediastinum/subcutaneous emphysema, fistulas, and airway obstruction related to tracheostomy, and procedure-related death)
Definitions
Co-morbidities were defined by ICD-10 codes in the medical records, that is, cardiovascular disease (I25 and/or I50), hypertension (I10), diabetes (E10/E11), asthma (J45), and chronic obstructive pulmonary disease (J44) in combination with active treatment. Immunosuppression was classified as systemic steroid treatment, radiation, or chemotherapy < 6 months prior to hospital admission(23). Kidney function was defined using the Kidney Disease: Improving Global Outcomes classification of chronic kidney disease based on the glomerular filtration rate (GFR) mL/min/1.73 m2.
Complications associated with tracheostomy were defined as events that had a potential negative impact on the patients’ clinical course and thus required intervention. All events occurring from the time of the procedure to the time of decannulation were included. The definitions of the complications are outlined in Table 1.
Table 1 - Definitions of tracheostomy-related complications
Haemorrhage
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In tracheal stoma, needing manual or pharmacological intervention
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Displaced tracheal cannula
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Displacement requiring manual repositioning
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Aspiration
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Visualization of gastric contents in the airway or clinical indications of aspiration
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Tracheal injury
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Lacerations or wounds related to the procedure or from chafing by the tracheal cannula
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Failed surgery
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Discontinuation of the procedure due to complications or unforeseen events
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Pneumothorax/pneumomediastinum/subcutaneous emphysema
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Verified by chest CT or clinical examination
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Airway obstruction
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Causing severe dyspnoea, needing physician attention
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Accidental decannulation
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Tracheal cannula dislodgement
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Stoma infection
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Culture verified infection resulting in change in antibiotics
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Fistula
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Tracheoarterial or tracheoesophageal fistula
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Ethical considerations
This study was approved by the Swedish Ethical Review Authority on August 26, 2020 (Dnr 2020-02758). Patient consent was waived due to the retrospective nature of the study.
Statistical analysis
All statistical analyses were performed using IBM SPSS Statistics (version 27.0; IBM Corp., Armonk, NY, USA). Data are presented as descriptive statistics, with categorical variables reported as frequencies (percentages). The continuous variables are presented as medians (interquartile ranges [IQRs]). The differences between the groups were tested using the chi-square test, the Mann-Whitney U test, Fisher’s exact test, or Student’s t-test, as appropriate. All tests were two-sided, and statistical significance was set at p < 0.05.