Maintaining the airways of patients with severe oral diseases such as oral cancer or oral infection, is one of the most important demands for oral maxillofacial surgery and various factors can affect postoperative airway maintenance. The factors could include cancer resection cancer, reconstruction, postoperative edema, inherent systemic diseases1,2,3 in oral cancer cases, as in odontogenic infection, infection site edema, airway distortion, or systemic diseases. These factors were cited as clinically important by practicing clinicians4,5,6.

Tracheostomy is an effective technique for airway maintanence after oral maxillofacial surgery. Because the demands of long-term postoperative airway maintenance can vary depending on the patient's circumstances, elective tracheostomy is recommended for patients with a high risk of airway obstruction. However, careful patient selection is required in elective tracheostomy because complications such as bleeding, local infection, pneumonia, obstruction or airway distortion, and airway stenosis can occur after a tracheostomy is performed7,8,9. Moreover, because of the invasive nature of the tracheostomy, this procedure can cause additional risks for the patient.

For these reasons, Kruse-Lösler et al.10 invented a scoring system based on tumor size and location, multiple complications, alcohol intake, and pathologic findings based on chest radiograph to determine whether to perform a tracheostomy.

Kruse-Lösler et al.10 conducted a significance test on 20 factors that can influence patients that require a tracheostomy. As a result, the research determined that significant factors included pathologic findings on chest posterior-anterior (PA) and underlying disease (systemic disease). However, Kruse-Lösler et al.'s scoring system10 lacked consideration in regards to surgical factors.

Cameron et al.11 introduced a standard for elective tracheostomy by scoring factors such as the tumor location, mandibulectomy, neck dissection, and reconstruction. However, insufficient consideration of the tumor size and systemic health condition was not included.

Similarly, Flynn et al.12,13,14,15 reported a severity score for each facial space infection site in dental infection patients, but this study is limited because it developed suggestions based on anatomical considerations and lacked systemic consideration.

In spite of these studies, a sufficient comprehensive and objective evaluation index for elective tracheostomy has not been developed. Crosher et al.16 predicted in their study on elective tracheostomy that an evaluation standard would benefit patients with the disease.

Therefore, this study was conducted to develop a comprehensive patient evaluation scoring system and to statistically revaluate the scoring system to prepare the system as an elective tracheostomy standard based on several factors. Furthermore, this study compared the average hospital day of postoperative oral cancer patients and severe infection patients in regards to tracheostomy performance.

Airway management is crucial for oromaxillofacial surgery patients that undergo sugery for severe oral disease and management may be difficult for the operating surgeon17. Therefore, recently, overnight intubation with an endotracheal tube has been introduced for cases in which challenging airway maintenance is predicted such as in postoperative edema18,19. This technique can only be used for a short time period, while severe edema is present, but is advantageous because it is minimally invasive and allows for a quick recovery. In contrast, Coyle et al.20 reported that almost every patient can be treated with overnight intubation for airway maintenance.

However, this technique is not optimal because the endotracheal tube can cause cause discomfort especially in conscious patients that are sensitive to oral intubation, hence, long-term maintenance can be very difficult. Therefore, after surgery, immediate removal is recommended after the patient recovers specific attributes. However, it can be challenging to determine the optimal time to remove the tube. Postoperative edema usually increases during the 2-3 days after surgery. Accordingly, removal one day after surgery, or 2-3 days after sugery, is considered untimely. Moreover, once the intubation tube is removed, it can complicate reintubation in emergency situations21, for example, reintubation is required if a patient experiences obstruction after the tube is removed. However, elevating the larynx is problematic in oral cancer and odontogenic infection surgery patients due to postoperative edema and this be associated with opening limitations which increase the risk for patients. In this situation, an emergency tracheostomy can be performed, but is conducted on a concious patient with head and neck edema which can also cause complications and increase the failure rate21.

In this aspect, elective tracheostomy is the most definite technique for maintaining the airway after surgery. Because long-term airway maintenance for up to a week may be warranted, an elective tracheostomy is recommended in high-risk patients after surgery, based on the patient's recovery status22. However, a tracheostomy is very invasive. Even though complications are very rare, intensive care is required in addition to a recovery period as well as cost after surgery increases23,24. Even though there is a possibility of postoperative airway obstruction it is important to determine the best indication to effectively treat patients.

In consideration of these challenges, this study researched and designed a new scoring system. Both the oral cancer and odontogenic infection groups were divided largely into two factors: a surgical factor and a systemic factor. First, in the oral cancer group, surgical factors were simplified into TNM stage and reconstruction methods based on studies on other surgical factors2,7,16,25,26, and for systemic factors, pathologic findings on chest PA and the number of systemic diseases were selected after referring to the study done by Cameron et al.11. Cameron et al.11 conducted a significant number of tests on 20 factors that could influence the need for tracheostomy. The significant systemic factors were pathologic findings on chest PA and systemic disease. In the odontogenic infection group, we referenced a study by Flynn et al.12,13,14,15 to evaluate the infection site and degree of infection. Likewise, systemic factors were set equally to the oral cancer patients based on information from the Cameron et al.'s study11. Moreover, age and CRP level were set as additional factors to compensate for consideration of the patient's systemic condition27,28,29,30.

A correlation survey on the tracheostomy score total and between each of the factors showed that TNM stage for oral cancer and infection site for odontogenic infection had the highest correlation. Both groups indicated that surgical factors are more important than systemic factors. However, this correlation was only a result of a factor of the scoring system suggested in this study and cannot currently be generalized. Furthermore, additional research is necessary to identify a new systemic factor with that is highly correlated with this systemizing the theory.

Interestingly in this study, the tracheostomy score was significantly correlated with both the hospital day and whether or not the tracheostomy was performed. For patients with a high score in the preoperative score system, early tracheostomy could be perfomed by predicting the invasiveness of surgery and recovery period in advance, which could enable patient management teams to increase safety and prevent emergency situations. Crosher et al.16 predicted that if such an evaluation index existed, patients would benefit greatly. Although a number of systemic diseases showed significant correlations, the pathologic finding on chest PA, one of the factors suggested in this study, was not significantly correlated with the total tracheostomy score in either group A or group B.

An optimal scoring system should not be complicated and should be discernable before operation or during operation10. However, strictly speaking, there the TNM stage factor can be limiting and accurate scoring may only be with histopathologic analysis based on radial resection. Even though such factors as the size of the tumor and overactivation of related lymph nodes can be detected in advance with positron emission tomography-computed tomography31, the exact TNM stage is difficult to discern.

For the oral cancer patients scoring system, a history of preoperative radiation therapy and previous surgery on the same area were intended to be included as contributing factors because patients with these histories tend to have altered anatomic landmarks and airway management can be difficult32. However, a number of patients in our hospital who met these criteria were not included in the study for statistical analysis because other factors were too limiting.

We also tried to include arterial blood gas analysis (ABGA) results at the first medical examination in the scoring system for odontogenic infection patients. Because ABGA is the most objective index to indicate the respiratory status of a patient with an obstructed airway due to infection or edema15. However, we could not include this factor in the scoring system because ABGA is not manifested as respiratory acidosis, which could have been used in this study, because it is multifactorial.

The scoring system suggested in this study is based on the premise that a tracheostomy should be performed in a patient that is above a specific score level. To achieve this, we calculated the sensitivity, specificity, PPV, and NPV based on the ROC curve. A score of 5 in oral cancer patients and a score of 6 in odontogenic patients showed the highest predictive value. However, these values are not associated with an absolute scoring system. In fact, in the oral cancer patient group (group A), 2 out of 28 patients with tracheostomy score of more than 5, which was the cutoff, did not receive a tracheostomy. In the odontogenic infection patients (group B), among patients with tracheostomy score of more than 6, which was the cutoff, 3 patients did not receive a tracheostomy.

For example, an oral cancer patient that underwent a tracheostomy recovered in the general ward since the patient had shown good progress after surgery. However, the patient suddenly experienced difficulty breathing due to delayed bleeding 4 days after the surgery happened. The patient was transferred to the intensive care unit and an emergency tracheostomy was performed. Although additional research and is necessary, the scoring system suggested in this study can be used as a auxiliary index for elective tracheostomy in severe oral disease patients.

In oral cancer patients, the TNM stage, and reconstruction were significantly correlated with the tracheostomy score. However, the pathologic findings on chest PA were not significantly correlated with the score. In odontogenic infection patients, the infection site, age, CRP level at the first visit, and systemic disease were significantly correlated with the tracheostomy score, but the pathologic findings on the chest PA were not correlated in this study.

A tracheostomy score of 5 for oral cancer patient and 6 for odontogenic infection patients is considered as a relevant cutoff to determine if an elective tracheostomy is indicated.

The elective tracheostomy evaluation system suggested in this study is expected to be practical and cover both surgical and systemic factors in patients with severe oral disease.