Could Beta blockade improve outcome after injury by modulating inflammatory profiles?

BACKGROUND: Cardioprotection with beta-receptor antagonists improves outcome in high risk patients undergoing elective surgery. Recent trials have demonstrated an association between beta blocker (BB) use and improved outcomes after injury. The mechanisms through which BB result in improved outcomes remain poorly elucidated. In vitro evidence supports that BB modulates the postinjury inflammatory response. The purpose of this study was to examine the effects of BB on inflammatory profiles in injured patients at increased risk for heart disease. METHODS: A pseudo-randomized, controlled trial of injured patients over 55 admitted to the intensive care unit was conducted. Patients were randomized to receive continuous BB or standard of care. Patients with a reported history of prehospital BB use were enrolled into an observational arm of the trial, continued on BB, and analyzed with the continuous BB group. Plasma interleukin (IL)-6 and IL-1beta levels were measured by enzyme-linked immunosorbent assay at baseline and day 1, 2, and 4 after BB initiation. Cytokine data were log transformed for normality assumptions. Repeated measures analysis of variance was used to test for within-group differences in cytokine levels over time. RESULTS: Forty-two patients were enrolled. Seventeen patients were randomized to the control group and 25 patients received continuous BB (10 randomized/15 observational). There was no difference in gender, age, prior history of heart disease, or admission heart rate, systolic blood pressure or initial base deficit between groups. Baseline levels of IL-6 and IL-1beta did not differ between groups. Levels of IL-6, but not IL-1beta, decreased over time in patients receiving BB (p = 0.04), whereas levels in controls remained unchanged (p = 0.27). There were no BB related complications. CONCLUSIONS: Use of BB decreases serum IL-6 levels over time in injured patients at risk for heart disease. This may contribute to improved outcomes noted in trauma patients receiving BB. Additionally, BB use in this population of patients is safe after endpoints of resuscitation have been met.

Serum B-type natriuretic peptide: a marker of fluid resuscitation after injury?

BACKGROUND: Excessive volume resuscitation after injury is associated with severe complications. B-type natriuretic peptide (BNP) is secreted from myocardium under increased wall stretch and is used in medical intensive care units (ICUs) as a noninvasive method to detect heart failure. However, the use of BNP as a marker of fluid overload during resuscitation from injury has not been previously described. METHODS: Serum BNP levels were prospectively followed in 134 trauma ICU patients. Levels were obtained at admission and at 12, 24, and 48 hours. Repeated measures analysis of variance was used to test for differences in BNP levels over time. Post hoc pairwise comparisons were made with Bonferroni correction when the omnibus test indicated significance. Chest films were obtained at 24 hours and scored for the presence of pulmonary edema by a radiologist blinded to BNP measurements (n = 45). Twenty-four hour BNP levels for patients with or without radiographic evidence of pulmonary edema were compared using nonparametric analysis (Mann-Whitney U). RESULTS: Admission BNP levels were low and increased with fluid resuscitation over time in all patients (p = 0.002) as well as in a subgroup of patients <60 years of age (p = 0.003). At 24 hours, 25 patients had no pulmonary edema evident on chest X-ray, whereas 20 were scored indicating that pulmonary edema was present. Patients with evidence of pulmonary edema had higher mean BNP levels at 24 hours (110 +/- 31 pg/mL) than did patients without edema (47.0 +/- 10.8 pg/mL) (p = 0.04). CONCLUSIONS: Serum BNP levels increase with resuscitation after injury and levels are higher in patients who develop pulmonary edema. These findings suggest that BNP might be a marker of excessive volume resuscitation after injury.

Quantity and quality of sleep in the surgical intensive care unit: are our patients sleeping?

BACKGROUND: The lack of adequate sleep during intensive care unit (ICU) admission is a frequently overlooked complication. Disrupted sleep is associated with immune system dysfunction, impaired resistance to infection, as well as alterations in nitrogen balance and wound healing. The effects of surgical ICU admission on patients' sleep quality and architecture remain poorly defined. The purpose of this study was to describe the quantity and quality of sleep as well as sleep architecture, as defined by polysomnography (PSG), in patients cared for in the surgical ICU. METHODS: A prospective observational cohort study was performed at our urban Level I trauma center. A convenience sample of surgical or trauma ICU patients underwent continuous PSG for up to 24 hours to evaluate sleep patterns. A certified sleep technician performed, monitored, and scored all PSG recordings. A single neurologist trained in PSG interpretation reviewed all PSG recordings. chi goodness-of-fit analysis was performed to detect differences in the proportion of time spent in stages 1 and 2 (superficial stages), stages 3 and 4 (deep stages), or rapid eye movement (REM) sleep between study patients and healthy historical controls. All PSG recordings were performed greater than 24 hours after the administration of a general anesthetic. Patients with traumatic brain injury were excluded. RESULTS: Sixteen patients were selected to undergo PSG recordings. Median age was 37.5 years (range, 20-83), 81.3% were male patients, 62.5% were injured, and 31.3% were mechanically ventilated. Total PSG recording time was 315 hours (mean, 19.7 hours per patient), total sleep time captured by PSG was 132 hours (mean, 8.28 hours per patient), and there were 6.2 awakenings per hour of sleep measured. ICU patients had an increase in the proportion of time spent in the superficial stages of sleep, and a decrease in the proportion of time spent in the deeper stages of sleep as well as a decrease in REM sleep compared with healthy controls (p < 0.001). CONCLUSIONS: Patients do achieve measurable sleep while cared for in a surgical ICU setting. However, sleep is fragmented and the quality of sleep is markedly abnormal with significant reductions in stages 3 and 4 and REM, the deeper restorative stages of sleep. Further studies on the effects of a strategy to promote sleep during ICU care are warranted.