Similar to postoperative fever, fever after the removal of a drainage tube is always a challenge for many doctors. The diagnostic workups for fever could be costly, waste time, and prolong the hospital stay of patients. Moreover, most of the evaluations failed to identify the cause of fever. In this study, we used acetaminophen (Tylenol) as a prophylactic treatment for fever after the removal of drainage tubes in lumbar surgery, and the results showed that this approach could significantly lower the possibility of fever.
To the best of our knowledge, our research was the first to focus on the problem of fever after the removal of a drainage tube placed during lumbar surgery. Many previous studies have focused on postoperative fever. The most acceptable conclusion was that fever was the physiological response due to the damage caused by surgical trauma, and the degree of fever was correlated with the extent of tissue trauma during surgery[4, 8, 11, 13]. The inflammation reaction stimulated by tissue trauma could trigger the release of cytokines such as IL1, IL6 and TNF-a in the local surgical area, and the released cytokines acted as endogenous pyrogens to stimulate the preoptic area of the hypothalamus to increase prostaglandin production, raising the thermoregulatory set point for body temperature[9, 13, 14, 19, 20]. Based on these theories, we proposed that when the drainage tube was removed, the local inflammatory cytokines could not flow out, and then a small hematoma formed. With the increase in pressure caused by the hematoma and the concentration of cytokines, the inflammatory cytokines could penetrate the vessel circulation and then raise the body temperature. Therefore, if we use acetaminophen in advance to depress the function of prostaglandin (Fig. 4), we could lower the possibility of fever when the drainage tube is removed. The results of the study proved our hypothesis.
Many previous studies could directly or indirectly support our proposal. The reports of Chmel et al  and Gemer et al  both suggested that hematoma of the wound site was the source of fever, which was in line with our thoughts. Many previous studies have stated that the postoperative drainage fluid is rich in inflammatory cytokines such as IL1, IL6 and TNF-a, and the levels of these cytokines are higher in fever patients[12, 16, 17]. Mark et al  and Gideon et al  both compared the fever rate of patients with or without drainage tubes postoperatively and declared that patients without postoperative drainage were more vulnerable to fever. More interesting, learning from Hao’s  research, we found that if the drainage tube is intermittently clamped after lumbar surgery, the patient was more likely to have fever. All the above conclusions could support our original idea that the removal of the drainage tube could stop the outflow of inflammatory cytokines and then cause fever.
Tylenol, a brand of acetaminophen, is a common analgesic-antipyretic medicine in our clinical treatment. This drug could inhibit prostaglandin synthase in the hypothalamic thermoregulation center and then reduce the production of prostaglandin. Based on what we discussed above, when the drainage tube was removed, the elevated cytokines could act on the hypothalamic thermoregulation center and cause a fever. The prophylactic medicine acetaminophen could depress the activity of prostaglandin synthase to fight against stimulation from the cytokines to synthase, and then lower the possibility of fever. The half-life of Tylenol is approximately 2 hours, so the serum concentration of acetaminophen would be too low to have an antipyretic effect the next day. It was not necessary to worry if the use of acetaminophen would mask signs of infection, and the number of infectious cases in the study group could prove this.
The concentrations of WBCs and CRP were not significantly different between groups in this study. As we observed, acetaminophen could only depress the activity of prostaglandin synthase but not suppress the inflammatory reaction caused by surgical trauma, so it was reasonable to accept this result. The length of hospital stay after drainage removal of the study group was shorter than that of the control group (2.23 days vs 2.82 days), but the difference was not significant because some patients asked to delay their discharge due to weekends or their personal condition.
Our study had some limitations. First, this was not a triple-blinded study. Second, due to limited funding, we did not directly test the changes in the concentrations of cytokines before and after the removal of the drainage tube. However, we were the first to focus on fever after the removal of drainage tubes for lumbar surgery, and our research proved that prophylactic treatment with acetaminophen could significantly lower the potential of developing fever.