This study found that a history of smoking and long stay time in PACU are both independently associated with high risks of ETI. Additionally, the 3-year OS of patients subjected to ETI was estimated to be far less than those without ETI, which was identified to be an independent risk factor affecting the OS of patients after esophagectomy. In this study, multiple relevant pre-operative, intra-operative, and resuscitation-related clinical parameters were extensively evaluated to assess for their association with ETI. These findings may be used to identify and reduce the post-operative complications and thereby prolong the OS in relevant cases.
This study also found that men account for the vast majority of patients with esophageal cancer, consistent with epidemiological characteristics. [9] Additionally, the patients subjected to ETI in the presented study were estimated to be older than the control patients, implying that elderly patients are more likely to undergo this serious post-operative ETI after esophagectomy than young patients. It has previously been shown that age is associated with the severity of complications after esophagectomy by an adjusted OR of 1.02 per year increase in age. [10] Naturally, elderly patients generally have reduced functional reserves of organ systems, and thus they are less tolerant to surgical trauma than young patients. Nevertheless, age by itself may not be as influential on post-operative outcomes as assumed, and treatment choice may be more important than age in old patients. [10] Thus, a pre-operative geriatric assessment is advisable to have a holistic view of the patient, which can provide an insight into the risks of post-operative complications. [11, 12]
In this study, there were more patients with a history of smoking in the ETI group than in the control group. However, the two groups did not significantly differ in pre-operative FEV1. Patients with a history of smoking often have varying degrees of small airway damage and chronic inflammation of the trachea or bronchus, which may cause respiratory function damage under mechanical ventilation or upon surgery.[13, 14] Pulmonary function tests are not sensitive enough to detect mild-to-moderate pulmonary function impairment. Furthermore, some patients with moderate or severe pulmonary dysfunction, who were excluded from the present study, may not tolerate radical esophagectomy, and neoadjuvant therapy might be considered as an alternative treatment. In short, a history of smoking is a risk factor for post- esophagectomy ETI. [15]
Inconsistent with the results of this study, a high BMI or history of thoracoabdominal surgery is generally assumed to complicate an operation and increase the incidence of post-operative complications. [16] It should be also noted that there is currently no plausible explanation for this assumption. Nevertheless, the small size of the study population may be the reason underlying this discrepancy.
A previous study has indicated that performing the surgery during off-hours, including weekends and nights, can increase the occurrence of intra-operative adverse events. [17] In the presented study, 57.1% of the patients subjected to ETI had received esophagectomy after 8:00 P.M, as opposed to 33.3% of the control patients. However, the results of small-sample regression analysis did not indicate any contribution of a night surgery to the incidence of post-operative ETI. Additionally, our previous study has indicated that ETI during off-hours is not associated with increased mortality in hospitalized patients. [5]
Previous studies have identified blood loss, hypotensive events, insufficient oxygen delivery, and a need for inotropic support during esophagectomy as peri-operative risk factors for post-operative anastomotic leakage. Oxygenation of the gastric tube resulting from reduced tissue perfusion is considered one of the main causes of insufficient anastomotic healing.[18] Therefore, maintenance of blood circulation and adequate tissue oxygenation during intra-operative and post-operative periods are presumably important. Additionally, pulmonary complications can result from intra-operative hypoxemia or hypotension, which trigger the release of proinflammatory mediators and activation of leucocytes. [19] In the current study, there were no patients with severe intra-operative hypotension or hypoxemia. Regarding peri-operative mean arterial pressure measurements, intra-operative blood loss, and a need for inotropic support, no differences were observed between the ETI and control groups. In general, the influence of each specific intra-operative or post-operative parameter on the occurrence of ETI was not elucidated. Perhaps, the intensities of these factors cumulatively affect the risk of ETI. However, the incidence of post-operative pulmonary complications or anastomotic leakage was significantly higher in the ETI group than in the control group.
After the operation, every patient with an endotracheal tube was sent to the PACU. Esophagectomy requires a thoracoabdominal combined incision, which is very traumatic, and lasts for > 5 h. Some patients had a long recovery time in the PACU. The patients in the ETI group were resuscitated in the PACU in approximately 120 min, yet the control patients were resuscitated in approximately 60 min. Because of hypoxemia, hemodynamic instability, or insufficient ventilation, 47.6% of the patients subjected to ETI and 28.6% of the control patients could not be extubated in the PACU and had to be sent to the surgical ward or intensive care unit. Three patients in the ETI group had to be reintubated after tracheal extubation in the PACU because of hypoxemia or hypercapnia. Previous studies have shown that a long duration of mechanical ventilation is associated with increased incidence of lung injury, lung infection, or regurgitation. [20, 21] Consistent with our findings, the study has found that a long stay time in PACU is another risk factor for post-esophagectomy ETI.
In this study, 57.1% of the patients subjected to ETI and 4.8% of the control patients had to undergo reoperation, including closed thoracic drainage, thoracic debridement, and esophageal reconstruction. Accordingly, the post-operative hospital stays and hospitalization costs of the patients subjected to ETI significantly increased. The in-hospital mortality of the patients subjected to ETI was 19.0%, whereas no control patient died in the hospital. The high incidence of post-operative pulmonary complications or anastomotic leakage in the ETI group may be one of the causes of the high in-hospital mortality rate post-ETI. The 3-year OS of the patients in the ETI and control groups was 47.6% and 85.7%, respectively. COX regression analysis revealed that ETI is an independent risk factor affecting the OS of patients after esophagectomy.