Methemoglobinemia is a rare condition that caused impairment of oxygen delivery manifested as spectrum of features ranging from mild desaturations to severe cyanosis and even death. It is rarely seen in the operative theatre and its incidence is scarcely reported. Even low risk patients are susceptible despite having no significant exposure to commonly reported precipitating oxidizing agents. We described a case of perioperative methemoglobinemia in a 10-year-old child, which was planned for foreign body removal in left ear. The operation went successfully; however, the child developed desaturation postoperatively. Arterial blood gas was measured, and methemoglobin levels were noticeably high at 27.1%. The child remained hemodynamically stable, monitored conservatively, and was successfully treated with intravenous methylene blue. We postulated that the cause of methemoglobinemia was intravenous fentanyl usage, as other oxidising agents were excluded. Clinicians must be aware of the possibility of perioperative methemoglobinemia causing unanticipated desaturations and unexplained cyanosis.

Introduction: The question as to whether epidural analgesia during labour can cause chronic low backpain has become a concern lately but this association has not been tested locally and remains controversial. This retrospective study aimed to ascertain the relationship between labour epidural analgesia and development of subsequent chronic low backpain. Methods: We contacted 200 primiparous women who had delivered by normal vaginal delivery via telephone at six months after delivery. While 100 of them had previously received epidural analgesia for labour, the other 100 had not. The women had to quantify their backpain by yes/no responses, numeric rating score, and impairment of daily function. Both the epidural and the non-epidural groups were compared using independent t-test and Chi-squared test while logistic regression was used to control for confounding factors. Results: The two groups had similar baseline characteristics except for body mass index, employment status and labour duration. The women who received epidural analgesia had significantly higher prevalence of low backpain at six months after delivery than those who had not (28% versus 9%, P = 0.001). However, the two groups did not show any difference in terms of numeric rating score or level of impairment of daily function. The low back pain at six months (epidural versus non-epidural) had an adjusted odds ratio of 8.1 (95% confidence interval 2.7 to 24.0, P <0.001). Conclusion: While epidural analgesia during labour was shown to be associated with chronic low back pain, this association may not be causal, suggesting the need for a randomized-controlled study in this area.