SBO is a common cause of emergency department visits, and there is a dilemma in the management of SBO: conservative treatment may result in delayed intestinal ischemia and necrosis; However, unnecessary emergency surgery could increase the incidence of severe complications and the formation of new adhesive bands. With the development of instruments, the usage of NITs could lead to a reduction of intestinal pressure in the early-stage and avoid intestinal ischemia, thus transforming the case from acute SBO to subacute SBO.
Previous studies have confirmed the efficacy of nasointestinal decompression through NITs for SBO [6, 12-15]; Similarly, in our center, NITs have confirmed therapeutic efficacy for SBO. The patients who have success with NITs decompression could avoid electrolyte imbalance and postoperative pneumonia, with a shortened length of hospital-stay and decreased hospital costs. However, in patients with tumors, the success rate of NITs insertion was significantly lower, which may owe to peritoneal metastasis that triggered mechanical intestinal obstruction in several portions, cannot be alleviated by single-one obstructive site decompression. Meanwhile, tumors accounted for 61.5% of the causes of obstruction in the SAE group and 19.5% in the non-SAE group (p=0.002). These results highlight that patients with malignant bowel obstruction could barely benefit form NITs insertion. HAN’s study showed that the cure rate of NITs for benign ileus was significantly higher than that for malignant ileus (38.1% vs. 6.7%, respectively; p=0.01) . As a result of a poor nutritional status, systemic deterioration and the multiple portions obstructions found in malignant small bowel obstruction, hampered the strategies for the treatment. Only 30-48.9% of the patients can be successfully treated, as mentioned in the literature. Patients with malignant bowel obstruction should be carefully selected for treatment with the aim of improving their quality of life [21-23].
Our research found that hypochloremia in the success group was lower than that in the failed group, which was related to the findings that hypochloremia closely increased mortality rates in severe patients [24-26]. We speculated that hypochloremia could be a marker of malnutrition in the patient before surgery. Moreover, it could be related to the status of preoperative chronic kidney disease and known heart failure with hypochloremia [27, 28]. In addition, insufficient fluid supplementation before surgery and fluid accumulation in the third space may lead to prerenal renal insufficiency, and during decompression, the electrolyte support cannot meet the body's needs, which may lead to the occurrence of hypochloremia after NITs insertion.
Even if the patient failed to achieve the goal of complete alleviation of SBO, NITs drainage of the luminal contents could reduce the internal pressure, ease bowel edema and find the cause of the obstruction. Moreover, the incidence of SAE was extremely low in all patients with NITs insertion (9.6%) (success group vs failure group: 1.5% vs 17.6%) (Table 6) [16, 29, 30]. We compared some previous studies on the incidence of complications during conservative treatment of intestinal obstruction [2, 31, 32]. It was obvious that the incidence of SAEs after NITs insertion in our study was not significantly higher than other conservative treatment (Table 7, 8). Different from previous study, no patients suffered with intestinal ischemia in our study, however, Intractable diarrhea and Methicillin-resistant staphylococcus aureus colitis occurred. Consistent with the report by Shogo Tanaka, patients after NITs insertion should pay attention to their intestinal flora and avoid the use of antibiotics (Table 9).
We also constructed a risk score system containing the relief of bowel obstruction symptoms and preoperative anemia, to predict the occurrence of SAEs after NITs insertion. Failure in decompression will lead to respiratory complications, while successful relief of bowel obstruction symptoms by NITs insertion can reduce the intra-abdominal pressure and the abdominal pain of the patients, thus improving respiratory ventilation and effectively reduce the incidence of pneumonia. Similarly, preoperative anemia also contributed to an increased risk of the occurrence of SAEs. As a carrier of oxygen, a reduction of hemoglobin may indicate intestinal ischemia and an insufficient oxygen support. Therefore, preoperative anemia should be corrected before NITs insertion to minimize the risk.
It is important to note that one case in the success group experienced gastrointestinal perforation. The patient accepted left liver resection and diagnosed as intestinal obstruction on the 13th day postoperatively (Figure 6A, 6B), then underwent NIT insertion followingly (Figure 6C). Unfortunately, gastrointestinal perforation and abdominal infection occurred (Figure 6D). After continuous abdominal irrigation, antibiotic therapy and infusion of plasma, the patient was able to eat semiliquid diet and discharged on the 30th day postoperatively. This case illustrated that even if SAEs occurred after NIT placement, effective decompression through the tube can lead to successful conservative treatment and avoid reoperation.
The present study is a retrospective cohort study that focuses on SAEs after NITs insertion using the PSM scoring system to detect the indication for NITs insertion. We constructed a risk score system including the hemoglobin level before NITs insertion and the relief of bowel obstruction symptoms after NITs insertion, to predict the occurrence of SAEs. There were some limitations in this study. Firstly, this was a retrospective study in a single center; thus, we will initiate a prospective, multicenter study to confirm our findings. Secondly, in this paper, data on conservative treatment of patients with SBO were lacking, and the complication rate of conservative treatment could only be determined by referring to previous studies. Thirdly, the severity of the intestinal obstruction in patients with conservative treatment may be generally mild, so NITs treatment or surgical treatment is not performed. It is better to further evaluate the degree of obstruction in combination with CT imaging data to evaluate the incidence of SAEs.