Alfred E. Baylor

Effects of vitamin D deficiency in critically ill surgical patients.

BACKGROUND The incidence of vitamin D deficiency in critically ill patients is reported to be up to 50%, with a 3-fold increase in predicted mortality, but limited data exist concerning vitamin D deficiency in critically ill surgical patients. METHODS Sixty-six adult surgical intensive care unit patients who had 25-hydroxyvitamin D serum levels evaluated from January 2010 to February 2011 were prospectively identified. Patients were divided into groups according to vitamin D level (<20 vs ≥20 ng/mL). RESULTS Of the 66 patients evaluated, 49 (74%) had vitamin D levels < 20 ng/mL, and 17 (26%) had vitamin D levels ≥ 20 ng/mL. Patients with vitamin D levels < 20 versus ≥ 20 ng/mL had longer lengths of hospital stay. Lengths of intensive care unit stay were clinically longer, although not significant. Infection rates tended to be higher (P = .09), and a higher incidence of sepsis was seen in the patients with vitamin D levels < 20 ng/mL. CONCLUSIONS Vitamin D levels < 20 ng/mL have a significant impact on length of stay, organ dysfunction, and infection rates. More data are needed on the value of supplementation to improve these outcomes.

The pivotal role of tumor necrosis factor-α in signaling apoptosis in intestinal epithelial cells under shock conditions

BACKGROUND Apoptosis is essential for the regulation of cell number and function of intestinal epithelial cells but may contribute to intestinal barrier failure after shock and other low-flow conditions to the gut. METHODS Caco2 intestinal cell monolayers were challenged with recombinant tumor necrosis factor (TNF). In a second group of experiments, Caco2 cells were exposed to bacteria and/or hypoxia followed by reoxygenation. Apoptosis was detected using annexin-V propidium-iodide staining. Cell culture supernatants were also obtained in the second group of experiments and TNF levels quantitated. Monolayer integrity was assessed by measurement of paracellular permeability and transepithelial electrical resistance. RESULTS Apical but not basal recombinant TNF increased Caco2 apoptosis. Exposure to either bacteria alone or hypoxia/reoxygenation alone did not increase apoptosis; however, the combined insults significantly increased apoptosis. The increased apoptosis occurred in a delayed fashion in both groups. TNF was released in a polar fashion, and the greatest levels were noted after exposure to both bacteria and hypoxia-reoxygenation. There was also an increase in paracellular permeability in this group; however, no change in transepithelial electrical resistance was noted. The effects on apoptosis and permeability were abrogated by anti-TNF antibodies. CONCLUSION Intestinal epithelial cell apoptosis contributes to barrier failure after shock conditions and is related to augmented TNF release.

The synergistic effects of hypoxia/reoxygenation or tissue acidosis and bacteria on intestinal epithelial cell apoptosis

BACKGROUND Clinical data indicate that gut perfusion deficits must be rectified within 24 hours after traumatic injury to decrease organ failure and death. Ischemia/reperfusion injury to the gut causes enterocyte apoptosis (Apo), which may contribute to intestinal barrier failure. The temporal response of enterocyte Apo to acidosis and hypoxia/reoxygenation (H/R) in vitro is unknown. The purpose of this study was to examine the effect of various time points of acidosis or H/R on enterocyte apoptosis and monolayer integrity in an in vitro model. METHODS Caco-2 cell monolayers were made acidic (Dulbeccos modified Eagles medium, pH 6.9) by hydrochloric acid or exposed to 95% nitrogen/5% carbon dioxide (hypoxia) and then 21% oxygen (reoxygenation). Escherichia coli C-25 were added to the apical media in subsets. Apo and necrosis were quantified by flow cytometry. Permeability was determined by fluorescein isothiocyanate-dextran. Transepithelial electrical resistance (TEER) indexed monolayer. RESULTS Extracellular acidosis and C-25 significantly increased apoptosis of Caco-2 cells at 18 hours (extracellular acidosis [EC] + C-25, 14.5 +/- 3.0; control, 3.8 +/- 0.8; p < 0.001 by analysis of variance). Similarly, the H/R + C-25 group showed a significant increase in apoptosis at 12 hours (H/R + C-25 vs. control, 22.86 +/- 2.12 vs. 3.74 +/- 0.7; p < 0.001 by analysis of variance). The permeability difference was not significant for EC + C-25 versus control at 18 hours (0.68 +/- 0.25 vs. 0.43 +/- 0.0.0.36, respectively; p > 0.05). The H/R + C-25 group had a profound increase in permeability over control at 12 hours (10.8 +/- 0.5 vs. 2.1 +/- 0.3, respectively; p < 0.001). The TEER was significantly lowered for EC versus control at 18 hours (458 +/- 1.5 vs. 468 +/- 8.2) and at 0, 6, and 18 hours for EC + C-25 (409 +/- 28.1, 443 +/- 16.8, and 438 +/- 8.9 vs. 455 +/- 6.5, 467 +/- 6.5, and 469 +/- 8.2, respectively). There was no significant change in the H/R and H/R + C-25 groups. CONCLUSION Synergism of H/R or tissue acidosis and bacteria caused increased Apo, TEER, and permeability in vitro.

Impact of minimizing diagnostic blood loss in the critically ill

BACKGROUND The use of a small-volume phlebotomy tube (SVPT) versus conventional-volume phlebotomy tube (CVPT) has led to a decrease in daily blood loss. Blood loss due to phlebotomy can lead ultimately to decreased rates of anemia and blood transfusions, which can be important in the critically ill patient. METHODS We compared SVPT vs CVPT retrospectively in critically ill adult patients age ≥18 years admitted to a surgical intensive care unit for ≥48 hours. CVPT were evaluated from January 2011 to May 2011 and SVPT from June 2012 to October 2012. RESULTS Amount of blood drawn for laboratory tests and transfusions were evaluated in 248 patients (116 SVPT vs 132 CVPT). When compared with CVPT, total blood volume removed (mean ± SD) with SVPT was less overall, 174 ± 182 mL vs 299 ± 355 mL, P = .001. Daily blood draws also were less, 22.5 ± 17.3 mL vs 31.7 ± 15.5 mL, P < .001. The units of packed red blood cells given were not significant, 4.4 ± 3.6 units vs 6.0 ± 8.2 units, P = .16. CONCLUSION The use of SVPT blood sampling led to a decreased amount of blood drawn. Strategies that use SVPT in a larger cohort also may decrease the number of transfusions in selected patients. Every effort should be made to use SVPT.

Hyperbaric oxygen therapy for systemic gas embolism after hydrogen peroxide ingestion.

BACKGROUND Hydrogen peroxide is a commonly available product and its ingestion has been demonstrated to produce in vivo gas bubbles, which can embolize to devastating effect. OBJECTIVE We report two cases of hydrogen peroxide ingestion with resultant gas embolization, one to the portal system and one cerebral embolus, which were successfully treated with hyperbaric oxygen therapy (HBO), and review the literature. CASE REPORT Two individuals presented to our center after unintentional ingestion of concentrated hydrogen peroxide solutions. Symptoms were consistent with portal gas emboli (Patient A) and cerebral gas emboli (Patient B), which were demonstrated on imaging. They were successfully treated with HBO and recovered without event. CONCLUSIONS As demonstrated by both our experience as well as the current literature, HBO has been used to successfully treat gas emboli associated with hydrogen peroxide ingestion. We recommend consideration of HBO in any cases of significant hydrogen peroxide ingestion with a clinical picture compatible with gas emboli.

Impact of evaluating antibiotic concentrations in abdominal abscesses percutaneously drained

BACKGROUND Appropriate antibiotic therapy and prompt drainage are essential for optimal results with abdominal abscesses. METHODS In this prospective study, 47 abdominal abscesses from 42 patients over 2 years who had percutaneous drainage were evaluated. Antibiotic concentrations were evaluated from the abscess fluid and correlated with clinical and microbiologic cure. RESULTS Only 23% of patients had appropriate antibiotic selection with optimal concentrations for the bacteria recovered. Piperacillin/tazobactam, cefepime, and metronidazole provided adequate concentrations in all except the largest abscesses, whereas fluconazole required higher doses in all abscesses. Vancomycin and ciprofloxacin levels were inadequate in most abscesses. With gram-negative aerobes, the use of appropriate antibiotics resulted in a relatively higher incidence of presumed eradication (100% [4 of 4] vs 75% [9 of 12], P = .26). With ≥ 3 organisms identified, clinical failure was significant (58% vs 13%, P = .01). CONCLUSIONS For optimal treatment, abdominal abscesses require prompt drainage and properly selected antibiotics at adequate doses. Essential information can be obtained from abscess cultures and their antibiotic concentrations.