A randomized trial on subject tolerance and the adverse effects associated with higher- versus lower-flow oxygen through a standard nasal cannula.

STUDY OBJECTIVE: Experts advocate the use of a standard nasal cannula to provide oxygen at flow rates of up to 15 L/minute during emergency intubation. However, because of concerns about potential patient discomfort, some providers avoid providing nasal cannula oxygen at flow rates greater than 6 L/minute. This trial is designed to determine the participants' ability to tolerate 10 minutes of nasal cannula oxygen at higher flow rates. METHODS: This was a prospective, randomized, crossover trial of healthy volunteers at an emergency department in New Zealand. Participants were randomized to first receive either higher-flow (15 L/minute) or lower-flow (6 L/minute) nasal cannula oxygen for 10 minutes. After a 1-hour washout period, they received the alternate flow rate for 10 minutes. The primary outcome was the ability to tolerate 10 minutes of the nasal cannula oxygen at each flow rate. The secondary outcome was the difference in discomfort between the flow rates as measured on a 100-mm visual analog scale. RESULTS: All 77 of the participants (100%) were able to tolerate 10 minutes at both flow rates. Participants rated the higher-flow nasal cannula oxygen as a mean of 25 mm (SD 20 mm) more uncomfortable than the lower-flow nasal cannula oxygen. One minute after the oxygen was discontinued, the mean difference in discomfort between the flow rates was a clinically insignificant 9.8 mm (SD 17 mm) more uncomfortable. There were no adverse events. CONCLUSION: Participants were able to tolerate higher-flow nasal cannula oxygen for 10 minutes without difficulty. Higher-flow nasal cannula oxygen at 15 L/minute was associated with some discomfort, but the discomfort quickly dissipated and caused no adverse events.

Differential production of cytokines following colorectal surgery.

BACKGROUND: Colorectal surgery is associated with a number of postoperative complications, including anastomotic leak and local recurrence. These complications are more common after rectal surgery than after colon surgery. Cytokines are secreted into the peritoneal cavity after colorectal surgery and have a number of metabolic and immunological effects. Hence we suggested that differential secretion of these may contribute to the differences in complications between colon and rectal surgeries. METHODS: Patients undergoing either elective rectal excision or colectomy for benign or malignant disease were recruited into the study. The region in relation to the anastomosis was drained with a silastic drain for 12-18 h. Drain fluid was collected on the morning following surgery. The drain fluid was assayed for interleukin (IL)-1beta, tumour necrosis factor-alpha, IL-6, IL-8, IL-10 and IL-13 using multiplexed biomarker immunoassays. RESULTS: Interleukin-8 concentrations were significantly higher in the region of the anastomosis after rectal excision compared with colectomy. Also, IL-6 levels were very high in both groups, but there was no significant difference between the groups. Although the concentrations of IL-10 were higher in the rectal group relative to the colectomy group, only low levels of this cytokine were present in the drain fluids. No other cytokines were consistently detected in significant concentrations. CONCLUSION: This study has shown that the concentration of IL-8 in the region of the anastomosis of patients who have undergone rectal surgery is much higher than those who have undergone colonic surgery. The increased level of IL-8 may provide a milieu conducive to local recurrence and anastomotic leak.

Central nervous system interleukin-8 production following neck of femur fracture.

AIM: To establish a proinflammatory cytokine profile of the cerebrospinal fluid (CSF) following trauma. BACKGROUND: Trauma is associated with a postinjury syndrome consisting of loss of weight and nitrogen, pyrexia, anorexia and fatigue. It has been proposed that cytokines are pathophysiologically involved in this syndrome but the site of action of these is unclear. Previous work in head injury models, supported by animal work, has suggested that one important site of action is the central nervous system (CNS). METHODS: Women who had sustained neck of femur fractures were enrolled (trauma group). CSF was collected at the time of spinal anaesthetic. Women undergoing elective lower limb surgery were recruited as controls. CSF and serum were assayed for Interleukin (IL) 1, 2, 4, 6, 8, 10, 12, interferon gamma, and tumour necrosis factor by cytometric bead array. RESULTS: In the trauma group, IL-8 was elevated in the CSF but not in the serum, while IL-6 was elevated in the serum but not in the CSF. IL-1beta, associated with elevated IL-12, was also detected in the serum of three of 11 trauma patients but none of the nine controls. No other cytokines were consistently detected. CONCLUSIONS: This study raises the possibility that IL-8, acting in the CNS, plays a role in the postinjury syndrome. It is unclear as to the mechanism by which CNS IL-8 is produced in trauma but a physiological role is supported by the known ability of the CNS to produce IL-8 and the presence of receptors for its action in the CNS.