Fibreoptic tracheal intubation is a useful technique in patients whose tracheas are dif®cult to intubate. 66 69 However, there are two major dif®culties with this technique. The ®rst is location of the glottis and insertion of a ®brescope into the trachea. Induction of general anaesthesia (with or without neuromuscular block) causes the soft palate, tongue and epiglottis to approximate to the posterior pharyngeal wall, 64 and thus little air space is left in the oropharynx for manoeuvring the tip of the ®brescope to locate the glottis. 58 The second dif®culty is insertion of a tube over the ®brescope into the trachea. There have been reports of failed tracheal intubation despite successful insertion of a ®brescope into the trachea. 67 89 To solve the ®rst dif®culty, several manoeuvres (such as thrusting the jaw forward, extension of the head, or traction of the tongue) have been proposed, and airway intubators (such as the Berman, 17 Ovassapian 66 and Williams 87 ) have been developed. In addition, there have been comprehensive articles discussing effective ways of teaching ®brescopy. 58 66 69 85 In contrast, there have been no textbooks or reviews which comprehensively deal with the second dif®culty, of advancing a tracheal tube over a ®brescope. Therefore, the main aim of this review article is to analyse the incidence of, causes of and possible solution to, the dif®culty in advancing a tube over a ®brescope into the trachea. Problems associated with dif®cult intubation over a ®brescopeDif®culty in ®breoptic intubation is associated with two major problems. The ®rst is apnoea. Time taken to intubate the trachea, and thus the duration of apnoea, is generally markedly longer for ®breoptic intubation than intubation using a laryngoscope. 74 80±82 As a consequence, stress responses, such as the increase in the heart rate and blood pressure, are more likely to be greater during ®breoptic intubation. 80±82 If apnoea continues unduly, the patient may become hypoxic. 56 It is particularly awkward if, after successful insertion of a ®brescope into the trachea despite considerable dif®culty in a patient with a dif®cult airway, it is still dif®cult to advance a tube over the scope into the trachea and the arterial haemoglobin oxygen saturation starts to decrease.The second problem associated with dif®cult ®breoptic intubation is damage to the upper airway. Repeated attempts at inserting a ®brescope into the trachea and advancing a tube over the scope increase the risk of injury to the larynx and surrounding tissues, leading to bleeding from, or oedema of, the tissues. Although rare, complete airway obstruction could occur during attempts at ®breoptic intubation even when the patient is not anaesthetized. 18 59 What tends to be ignored is that at no time during insertion of a tracheal tube over a ®brescope can the tip of the tube be seen directly. Therefore, a tracheal tube should be advanced over a ®brescope with great caution, particularly in patients with pathological changes to the glottis or surrounding tissues. 44 ...
A prominent feature of various inflamed and diseased tissue is the presence of low oxygen tension (hypoxia). Effector cells of the innate immune system must maintain their viability and physiologic functions in a hypoxic microenvironment. Monocytes circulating in the bloodstream differentiate into macrophages. During this process, cells acquire the ability to exert effects at hypoxic sites of inflammation. The transcription factor hypoxia-inducible factor 1 (HIF-1) mediates adaptive responses to reduced oxygen availability. In this study, we demonstrated that lipopolysaccharide (LPS) induces HIF-1 activation by enhancing both HIF-1alpha protein expression through a translation-dependent pathway and HIF-1alpha transcriptional activity in THP-1 human myeloid cells that have undergone macrophage differentiation but not in undifferentiated monocytic THP-1 cells. LPS-induced HIF-1 activation was blocked by treatment with antioxidant (N-acetylcysteine or thioredoxin-1), NADPH oxidase inhibitor (diphenyleneiodonium), indicating that reactive oxygen species generated in response to LPS are essential in this process. LPS-mediated activation of HIF-1 was independent of NF-kappaB activity. LPS-induced ROS generation and HIF-1 activation required the expression of Toll-like receptor 4 or myeloid differentiation factor (MyD) 88, thus providing a molecular basis for the selective activation of HIF-1 in differentiated THP-1 cells.
SummaryThere are two major subpopulations of peripheral helper T lymphocytes: T helper 1 (Th1) and T helper 2 (Th2) cells. Surgical stress increases the number of Th2 cells, and decreases that of Th1 cells, resulting in a decrease in the Th1 ⁄ Th2 ratio, and, consequently, in suppressed cellmediated immunity. Since anaesthesia can suppress the stress response to surgery, it may inhibit the decrease in the Th1 ⁄ Th2 ratio. Using flow cytometry, we studied whether propofol anaesthesia (n = 9) or isoflurane anaesthesia (n = 9) had more effect on the decrease in the Th1 ⁄ Th2 ratio after surgery in patients undergoing craniotomy. The Th1 ⁄ Th2 ratio decreased significantly after isoflurane anaesthesia (p = 0.011), while it did not change after propofol anaesthesia. The ratio was significantly lower with isoflurane than propofol (p = 0.009). Propofol anaesthesia attenuated the surgical stress-induced adverse immune response better than isoflurane anaesthesia.
Propofol and midazolam are the most widely used sedatives in the intensive care setting after surgery. We studied whether these sedatives had any antitumor immunity effects in mice. Mice were given intraperitoneal injections of propofol or midazolam and subcutaneous inoculation of tumor cells (EL4). Then, spleen cells were collected and the in vitro activity of cytotoxic T lymphocytes (CTL) was measured using flow cytometry. The in vitro activity of CTL against EL4 was significantly greater after propofol injection compared with its vehicle (Intralipid) or saline. Midazolam had no effect on CTL activity. We also studied whether tumor growth in vivo was affected by the administration of propofol. Tumor growth was significantly suppressed in mice that were given propofol, compared with tumor growth in mice given saline. Therefore, it is concluded that propofol may have a beneficial effect on antitumor immunity in mice.
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