Preliminary evaluation of near infrared spectroscopy as a method to detect plasma leakage in children with dengue hemorrhagic fever.

BACKGROUND: Dengue viral infections are prevalent in the tropical and sub-tropical regions of the world, resulting in substantial morbidity and mortality. Clinical manifestations range from a self-limited fever to a potential life-threatening plasma leakage syndrome (dengue hemorrhagic fever). The objective of this study was to assess the utility of near infrared spectroscopy (NIRS) measurements of muscle oxygen saturation (SmO2) as a possible continuous measure to detect plasma leakage in children with dengue. METHODS: Children ages 6 months to 15 years of age admitted with suspected dengue were enrolled from the dengue ward at Queen Sirikit National Institute for Child Health. Children were monitored daily until discharge. NIRS data were collected continuously using a prototype CareGuide Oximeter 1100 with sensors placed on the deltoid or thigh. Daily ultrasound of the chest and a right lateral decubitus chest x-ray the day after defervescence were performed to detect and quantitate plasma leakage in the pleural cavity. RESULTS: NIRS data were obtained from 19 children with laboratory-confirmed dengue. Average minimum SmO2 decreased for all subjects prior to defervescence. Average minimum SmO2 subsequently increased in children with no ultrasound evidence of pleural effusion but remained low in children with pleural effusion following defervescence. Average minimum SmO2 was inversely correlated with pleural space fluid volume. ROC analysis revealed a cut-off value for SmO2 which yielded high specificity and sensitivity. CONCLUSIONS: SmO2 measured using NIRS may be a useful guide for real-time and non-invasive identification of plasma leakage in children with dengue. Further investigation of the utility of NIRS measurements for prediction and management of severe dengue syndromes is warranted.

Comparison of Noninvasive pH and Blood Lactate as Predictors of Mortality in a Swine Hemorrhagic Shock with Restricted Volume Resuscitation Model.

Recent clinical studies have demonstrated that high blood lactate in the prehospital setting and poor lactate clearance in the emergency department are predictive of in-hospital mortality. This analysis of data collected from a swine model of hemorrhage and restricted volume resuscitation investigated the hypotheses that noninvasive muscle pH (pHm) and H clearance would predict mortality, and the responses would be similar between pHm and lactate. Data from a set of 57 swine were analyzed over the first 2 h after controlled hemorrhage and uncontrolled splenic bleeding. Surviving animals were ones that lived for the full 5-h experimental period. Venous lactate was determined at baseline, shock, and at 30, 60, and 120 min after injury. Spectra were collected continuously from the posterior thigh using a prototype CareGuide 1100 Oximeter and pHm calculated from the spectra; H concentration was determined from pHm. Lactate clearance rate was calculated from the difference in lactate concentration at 120 min and shock, and H clearance was calculated in a similar manner. Comparison of the area under the receiver operator characteristic curves was used to assess prediction of survival at 5 h after injury. At 120 min after injury, lactate, lactate clearance, noninvasive pHm, and noninvasive H clearance were equivalent predictors of mortality each with a receiver operator characteristic area under the curve of 0.87. Thresholds for single lactate (<3.8 mmol/L) or pHm (>7.30) determinations were found to be consistent with a resuscitation goal targeted to reverse acidosis. Continuous, noninvasive pHm monitoring may provide a substitute for lactate measurement in trauma patients, particularly in the prehospital and emergency department settings.

Investigation of noninvasive muscle pH and oxygen saturation during uncontrolled hemorrhage and resuscitation in swine.

This study evaluated noninvasively determined muscle pH (pHm) and muscle oxygen saturation (SmO2) in a swine shock model that used uncontrolled hemorrhage and restricted volume resuscitation. Anesthetized 40-kg female swine underwent hemorrhage until 24 mL/kg of blood was removed (n = 26), followed by transection of the spleen, causing uncontrolled hemorrhage throughout the remainder of the protocol. After 15 min, 15 mL/kg of resuscitation fluid (Hextend, fresh-frozen plasma or platelets) was given for 30 min. Arterial and venous blood gases were measured at baseline, shock, end of resuscitation, and end of the study (death or 5 h), along with lactate and base excess. In addition, seven animals underwent a sham procedure. Spectra were collected continuously from the posterior thigh using a prototype CareGuide 1100 Oximeter, and pHm and SmO2 were calculated from the spectra. A two-factor analysis of variance with repeated measures followed by Tukey post hoc comparisons was used to compare experimental factors. It was shown that, for both pH and SO2, venous and muscle values were similar to each other at the end of the resuscitation period and at the end of the study for both surviving and nonsurviving animals. pH and SO2, venous and muscle, significantly declined as a result of bleeding, but lactate and base excess did not show significant changes during this period. Noninvasive pHm and SmO2 tracked the adequacy of resuscitation in real time, indicating at the time all of the fluid was delivered, which animals would live and which would die. The results of this swine study indicate that further evaluation on trauma patients is warranted.

[Drug resistance of methicillin resistant Staphylococcus strains in burn ward and relative analysis].

OBJECTIVE: To study the distribution and drug resistance of methicillin resistant Staphylococcus strains in various specimens of inpatients in burn wards, and to provide reference for clinical treatment. METHODS: Bacteria were isolated from specimens of wound exudate, blood, sputum, and bronchoalveolar lavage fluid etc., which were collected from patients hospitalized in our burn wards from January 2008 to December 2010. The bacteria were routinely cultured and identified. Drug resistance of the Staphylococci to 15 antibiotics commonly used in clinic was identified by K-B disk diffusion method. Data were processed with statistical software WHONET 5.5. The homology of 40 strains of methicillin resistant Staphylococcus aureus (MRSA) was analyzed by pulsed-field gel electrophoresis (PFGE). RESULTS: Altogether 386 strains of Staphylococcus were isolated, including 196 strains of Staphylococcus aureus and 190 strains of coagulase negative Staphylococcus. The mean annual isolation rates of MRSA and methicillin resistant coagulase negative Staphylococcus (MRCoNS) were respectively 73.00% (143/196) and 74.20% (141/190). The resistance rates of MRSA and MRCoNS to ß-lactams drugs, such as penicillin, oxacillin, cefazolin, and cefuroxime were 100.00% in every year. No Staphylococcus strains resistant to vancomycin, teicoplanin, or linezolid were found. Three different PFGE patterns A, B, and C were identified among 40 MRSA strains, including 33 strains of type A (30 strains in sub-type A1 and 3 strains in sub-type A2), 6 strains of type B (respectively 3 strains in sub-types B1 and B2), and 1 strain of type C. CONCLUSIONS: The isolation rates of MRSA and MRCoNS were high in our burn wards from January 2008 to December 2010. All of them showed strong drug resistance property, and they were multidrug resistant. The most prevalent strain was PFGE type A.

Lightweight noninvasive trauma monitor for early indication of central hypovolemia and tissue acidosis: a review.

BACKGROUND: Hemorrhage is a major cause of soldier death; it must be quickly identified and appropriately treated. We developed a prototype patient monitor that noninvasively and continuously determines muscle oxygen saturation (SmO2), muscle pH (pHm), and a regional assessment of blood volume (HbT) using near-infrared spectroscopy. Previous demonstration in a model of progressive, central hypovolemia induced by lower body negative pressure (LBNP) showed that SmO2 provided an early indication of impending hemodynamic instability in humans. In this review, we expand the number of subjects and provide an overview of the relationship between the muscle and sublingual microcirculation in this model of compensated shock. METHODS: Healthy human volunteers (n = 30) underwent progressive LBNP in 5-minute intervals. Standard vital signs, along with stroke volume (SV), total peripheral resistance, functional capillary density, SmO2, HbT, and pHm were measured continuously throughout the study. RESULTS AND DISCUSSION: SmO2 and SV significantly decreased during the first level of central hypovolemia (-15 mm Hg LBNP), whereas vital signs were later indicators of impending cardiovascular collapse. SmO2 declined with SV and inversely with total peripheral resistance throughout LBNP. HbT was correlated with declining functional capillary density, suggesting vasoconstriction as a cause for decreased SmO2 and subsequently decreased pHm. CLINICAL TRANSLATION: The monitor has been miniaturized to a 58-g solid-state sensor that is currently being evaluated on patients with dengue hemorrhagic fever. Early results demonstrate significant decreases in SmO2 similar to those observed with progressive reductions in central blood volume. As such, this technology has the potential to (1) provide a monitoring capability for both nontraumatic and traumatic hemorrhage and (2) help combat medics triage casualties and monitor patients during lengthy transport from combat areas.

Investigation of spectral interferences on the accuracy of broadband CW-NIRS tissue SO(2) determination.

An accurate SO(2) prediction method for using broadband continuous-wave diffuse reflectance near infrared (NIR) spectroscopy is proposed. The method fitted the NIR spectra to a Taylor expansion attenuation model, and used the simulated annealing method to initialize the nonlinear least squares fit. This paper investigated the effect of potential spectral interferences that are likely to be encountered in clinical use, on SO(2) prediction accuracy. The factors include the concentration of hemoglobin in blood, the volume of blood and volume of water in the tissue under the sensor, reduced scattering coefficient, µ(s)', of the muscle, fat thickness and the source-detector spacing. The SO(2) prediction method was evaluated on simulated muscle spectra as well as on dual-dye phantoms which simulate the absorbance of oxygenated and deoxygenated hemoglobin.

[Investigation of 728 strains of infectious bacteria in burn ward and analysis of their antibiotic resistance].

OBJECTIVE: To study the infectious strains of bacteria in our burn ward in recent 5 years, and analyze their antibiotic resistance. METHODS: Bacteria were isolated from the wound excretions of 306 burn patients hospitalized during 2001 to 2006 for analyzing their strains and their antibiotic resistance. RESULTS: 378 strains were Grams positive bacteria, among them Staphylococcus aureus was the predominant strain. Further analysis showed that methicillin resistant staphylococcus aureus (MRSA) ranked the first in occurrence, followed by methicillin-resistance Staphylococcus epidermidis (MRSE) and Enterococcus fecalis, 338 strains were Gram negative bacteria, and among them Acinetobacter baumannii was predominant, and Enterobacter cloacae and Pseudomonas aeruginosa ranked the 2nd and 3rd. Twelve strains were fungi. CONCLUSION: Drug resistance to antibiotics in our burn ward may be related to the beta-lactamases from acinetobacter baumannii and multiple-drug-resistance of MRSA.

[The isolation of acinetobacter strain from burn wound and the analysis of its antibiotic resistance].

OBJECTIVE: To investigate the distribution and drug resistance of acinetobacter isolated from burn wounds. METHODS: The acinetobacter strains were isolated and identified by routine methods. Based on the recommendation of NCCLS, AmpC enzyme was determined by cefoxiti three-dimensional test, ESBLs by disk diffusion method and bacterial susceptibility by Kirby-Bauer agar diffusion method. RESULTS: Among the 69 strains of acinetobacter clinically isolated from burn wounds, 52 were baumannii (75.6%). The acinetobacter strains were identified to be highly resistant to 17 kinds of antibiotics. The drug resistance rate of beta-lactamase-producing strains (68.25%) was higher than that of non-beta-lactamase-producing strains (20.33%). The strains isolated in our burn ward exhibited multiple drug resistance which was mainly due to the production of many kinds of beta-lactamases. Among the 38 strains of beta-lactamase-producing acinetobacter, those producing AmpC beta-lactamase (AmpC BLA) accounted for 42.1%. CONCLUSION: Acinetobacter strain was one of the pathogens in burn wound infection, and its isolation and identification of its drug resistance could be beneficial to the doctors to make right choice of antibiotics.