Urinary bladder partial carbon dioxide tension during hemorrhagic shock and reperfusion: an observational study

INTRODUCTION: Continuous monitoring of bladder partial carbon dioxide tension (PCO(2)) using fibreoptic sensor technology may represent a useful means by which tissue perfusion may be monitored. In addition, its changes might parallel tonometric gut PCO(2). Our hypothesis was that bladder PCO(2), measured using saline tonometry, will be similar to ileal PCO(2 )during ischaemia and reperfusion. METHOD: Six anaesthetized and mechanically ventilated sheep were bled to a mean arterial blood pressure of 40 mmHg for 30 min (ischaemia). Then, blood was reinfused and measurements were repeated at 30 and 60 min (reperfusion). We measured systemic and gut oxygen delivery and consumption, lactate and various PCO(2 )gradients (urinary bladder–arterial, ileal–arterial, mixed venous–arterial and mesenteric venous–arterial). Both bladder and ileal PCO(2 )were measured using saline tonometry. RESULTS: After bleeding systemic and intestinal oxygen supply dependency and lactic acidosis ensued, along with elevations in PCO(2 )gradients when compared with baseline values (all values in mmHg; bladder ΔPCO(2 )3 ± 3 versus 12 ± 5, ileal ΔPCO(2 )9 ± 5 versus 29 ± 16, mixed venous–arterial PCO(2 )5 ± 1 versus 13 ± 4, and mesenteric venous–arterial PCO(2 )4 ± 2 versus 14 ± 4; P < 0.05 versus basal for all). After blood reinfusion, PCO(2 )gradients returned to basal values except for bladder ΔPCO(2), which remained at ischaemic levels (13 ± 7 mmHg). CONCLUSION: Tissue and venous hypercapnia are ubiquitous events during low flow states. Tonometric bladder PCO(2 )might be a useful indicator of tissue hypoperfusion. In addition, the observed persistence of bladder hypercapnia after blood reinfusion may identify a territory that is more susceptible to reperfusion injury. The greatest increase in PCO(2 )gradients occurred in gut mucosa. Moreover, the fact that ileal ΔPCO(2 )was greater than the mesenteric venous–arterial PCO(2 )suggests that tonometrically measured PCO(2 )reflects mucosal rather than transmural PCO(2). Ileal ΔPCO(2 )appears to be the more sensitive marker of ischaemia

Effects of volume resuscitation on splanchnic perfusion in canine model of severe sepsis induced by live Escherichia coli infusion

INTRODUCTION: We conducted the present study to investigate whether early large-volume crystalloid infusion can restore gut mucosal blood flow and mesenteric oxygen metabolism in severe sepsis. METHODS: Anesthetized and mechanically ventilated male mongrel dogs were challenged with intravenous injection of live Escherichia coli (6 × 10(9 )colony-forming units/ml per kg over 15 min). After 90 min they were randomly assigned to one of two groups – control (no fluids; n = 13) or lactated Ringer's solution (32 ml/kg per hour; n = 14) – and followed for 60 min. Cardiac index, mesenteric blood flow, mean arterial pressure, systemic and mesenteric oxygen-derived variables, blood lactate and gastric carbon dioxide tension (PCO(2); by gas tonometry) were assessed throughout the study. RESULTS: E. coli infusion significantly decreased arterial pressure, cardiac index, mesenteric blood flow, and systemic and mesenteric oxygen delivery, and increased arterial and portal lactate, intramucosal PCO(2), PCO(2 )gap (the difference between gastric mucosal and arterial PCO(2)), and systemic and mesenteric oxygen extraction ratio in both groups. The Ringer's solution group had significantly higher cardiac index and systemic oxygen delivery, and lower oxygen extraction ratio and PCO(2 )gap at 165 min as compared with control animals. However, infusion of lactated Ringer's solution was unable to restore the PCO(2 )gap. There were no significant differences between groups in mesenteric oxygen delivery, oxygen extraction ratio, or portal lactate at the end of study. CONCLUSION: Significant disturbances occur in the systemic and mesenteric beds during bacteremic severe sepsis. Although large-volume infusion of lactated Ringer's solution restored systemic hemodynamic parameters, it was unable to correct gut mucosal PCO(2 )gap

Effects of external global noise on the catalytic CO oxidation on Pt(110)

Oxidation reaction of CO on a single platinum crystal is a reaction-diffusion system that may exhibit bistable, excitable, and oscillatory behavior. We studied the effect of a stochastic signal artificially introduced into the system through the partial pressure of CO. First, the external signal is employed as a turbulence suppression tool, and second, it modifies the boundaries in the bistable transition between the CO and oxygen covered phases. Experiments using photoemission electron microscopy (PEEM) together with numerical simulations performed with the Krischer-Eiswirth-Ertl (KEE) model are presented.Comment: 15 pages, 7 figures, accepted in J. Chem. Phy

Open ventral hernia repair with a composite ventral patch : final results of a multicenter prospective study

Background: This study assessed clinical outcomes, including safety and recurrence, from the two-year follow-up of patients who underwent open ventral primary hernia repair with the use of the Parietex (TM) Composite Ventral Patch (PCO-VP). Methods: A prospective single-arm, multicenter study of 126 patients undergoing open ventral hernia repair for umbilical and epigastric hernias with the PCO-VP was performed. Results: One hundred twenty-six subjects (110 with umbilical hernia and 16 with epigastric hernia) with a mean hernia diameter of 1.8cm (0.4-4.0) were treated with PCO-VP. One hundred subjects completed the two-year study. Cumulative hernia recurrence was 3.0% (3/101; 95%CI: 0.0-6.3%) within 24months. Median Numeric Rating Scale pain scores improved from 2 [0-10] at baseline to 0 [0-3] at 1 month (P<0.001) and remained low at 24months 0 [0-6] (P<0.001). 99% (102/103) of the patients were satisfied with their repair at 24months postoperative. Conclusions: The use of PCO-VP to repair primary umbilical and epigastric defects yielded a low recurrence rate, low postoperative and chronic pain, and high satisfaction ratings, confirming that PCO-VP is effective for small ventral hernia repair in the two-year term after implantation. Trial registration: The study was registered publically at clinicaltrials.gov (NCT01848184 registered May 7, 2013)