Adenylate Kinase-Catalyzed Reactions of AMP in Pieces: Specificity for Catalysis at the Nucleoside Activator and Dianion Catalytic Sites.

The pressure to optimize the enzymatic rate acceleration for adenylate kinase (AK)-catalyzed phosphoryl transfer has led to the evolution of an induced-fit mechanism, where the binding energy from interactions between the protein and substrate adenosyl group is utilized to drive a protein conformational change that activates the enzyme for catalysis. The adenine group of adenosine contributes 11.8 kcal mol-1 to the total ≥14.7 kcal mol-1 adenosine stabilization of the transition state for AK-catalyzed phosphoryl transfer to AMP. The relative third-order rate constants for activation of adenylate kinase, by the C-5 truncated adenosine 1-(ß-d-erythrofuranosyl)adenine (EA), for catalysis of phosphoryl transfer from ATP to phosphite dianion (HP, kcat/KHPKAct = 260 M-2 s-1), fluorophosphate (47 M-2 s-1), and phosphate (9.6 M-2 s-1), show that substitution of -F for -H and of -OH for -H at HP results, respectively, in decreases in the reactivity of AK for catalysis of phosphoryl transfer due to polar and steric effects of the -F and -OH substituents. The addition of a 5'-CH2OH to the EA activator results in a 3.0 kcal mol-1 destabilization of the transition state for AK-activated phosphoryl transfer to HP due to a steric effect. This is smaller than the 8.3 kcal mol-1 steric effect of the 5'-CH2OH substituent at OMP on HP-activated OMPDC-catalyzed decarboxylation of 1-(ß-d-erythrofuranosyl)orotate. The 2'-OH ribosyl substituent shows significant interactions with the transition states for AK-catalyzed phosphoryl transfer from ATP to AMP and for adenosine-activated AK-catalyzed phosphoryl transfer from ATP to HP.

Avoiding the Use of Halogenated Anesthetic Agents for Uterine Relaxation in Open Mid-Gestation Fetal Surgery: A Case Report.

INTRODUCTION: Profound uterine relaxation is required for open fetal surgery. This is typically achieved by the administration of high-dose halogenated anesthetic agents. However, this anesthetic technique is associated with adverse cardiovascular effects in the fetus and may have long-term neurocognitive effects as well. CASE PRESENTATION: We pre-sent reports for 2 patients in whom uterine relaxation was maintained with nitroglycerin and magnesium infusions without any exposure to halogenated anesthetic agents. There were no adverse fetal or maternal effects from this technique. DISCUSSION/CONCLUSION: To the best of our knowledge, these are the first reports of open fetal surgery being performed without the use of halogenated anesthetic agents. This has potential short- and long-term benefits for the fetus, particularly as more complex and longer duration minimally invasive procedures are developed.

Epidemiology of Enterococcus , Staphylococcus aureus , Klebsiella , Acinetobacter , Pseudomonas , and Enterobacter Species Transmission in the Pediatric Anesthesia Work Area Environment With and Without Practitioner Use of a Personalized Body-Worn Alcohol Dispenser.

BACKGROUND: Personalized body-worn alcohol dispensers may serve as an important tool for perioperative infection control, but the impact of these devices on the epidemiology of transmission of high-risk Enterococcus , Staphylococcus aureus , Klebsiella, Acinetobacter , Pseudomonas , and Enterobacter (ESKAPE) pathogens is unknown. We aimed to characterize the epidemiology of ESKAPE transmission in the pediatric anesthesia work area environment with and without a personalized body-worn alcohol dispenser. METHODS: This controlled before and after study included 40 pediatric patients enrolled over a 1-year study period. Two groups of operating room cases were compared: (1) operating room cases caring for patients with usual care (December 17, 2019, to August 25, 2020), and (2) operating room cases caring for patients with usual care plus the addition of a personalized, body-worn alcohol hand rub dispenser (September 30, 2020, to December 16, 2020). Operating rooms were randomly selected for observation of ESKAPE transmission in both groups. Device use was tracked via wireless technology and recorded in hourly hand decontamination events. RESULTS: Anesthesia providers used the alcohol dispenser 3.3 ± 2.1 times per hour. A total of 57 ESKAPE transmission events (29 treatment and 28 control) were identified. The personalized body-worn alcohol dispenser impacted ESKAPE transmission by increasing the contribution of provider hand contamination at case start (21/29 device versus 10/28 usual care; relative risk, [RR] 2.03; 99.17% confidence interval [CI], 1.025-5.27; P = .0066) and decreasing the contribution of environmental contamination at case end (3/29 device versus 12/28 usual care; RR, 0.24; 99.17% CI, 0.022-0.947; P = .0059). ESKAPE pathogen contamination involved 20% (8/40) of patient intravascular devices. There were 85% (34/40) of preoperative patient skin surfaces contaminated with ≥1 (1.78 ± 0.19 [standard deviation {SD}]) ESKAPE pathogens. CONCLUSIONS: A personalized body-worn alcohol dispenser can impact the epidemiology of ESKAPE transmission in the pediatric anesthesia work area environment. Improved preoperative patient decolonization and vascular care are indicated to address ESKAPE pathogens among pediatric anesthesia work area reservoirs.

Adenylate Kinase-Catalyzed Reaction of AMP in Pieces: Enzyme Activation for Phosphoryl Transfer to Phosphite Dianion.

The binding of adenosine 5'-triphosphate (ATP) and adenosine 5'-monophosphate (AMP) to adenylate kinase (AdK) drives closure of lids over the substrate adenosyl groups. We test the hypothesis that this conformational change activates AdK for catalysis. The rate constants for Homo sapiens adenylate kinase 1 (HsAdK1)-catalyzed phosphoryl group transfer to AMP, kcat/Km = 7.0 × 106 M-1 s-1, and phosphite dianion, (kHPi)obs ≤1 × 10-4 M-1 s-1, show that the binding energy of the adenosyl group effects a ≥7.0 × 1010-fold rate acceleration of phosphoryl transfer from ATP. The third-order rate constant of kcat/KHPiKEA = 260 M-2 s-1 for 1-(ß-d-erythrofuranosyl)adenine (EA)-activated phosphoryl transfer to phosphite dianion was determined, and the isohypophosphate reaction product characterized by 31P NMR. The results demonstrate the following: (i) a ≥14.7 kcal/mol stabilization of the transition state for phosphoryl transfer by the adenosyl group of AMP and a ≥2.6 × 106-fold rate acceleration from the EA-driven conformational change and (ii) the recovery of ≥8.7 kcal/mol of this transition state stabilization for EA-activated phosphoryl transfer from ATP to phosphite.

Phosphodianion Activation of Enzymes for Catalysis of Central Metabolic Reactions.

The activation barriers ΔG⧧ for kcat/Km for the reactions of whole substrates catalyzed by 6-phosphogluconate dehydrogenase, glucose 6-phosphate dehydrogenase, and glucose 6-phosphate isomerase are reduced by 11-13 kcal/mol by interactions between the protein and the substrate phosphodianion. Between 4 and 6 kcal/mol of this dianion binding energy is expressed at the transition state for phosphite dianion activation of the respective enzyme-catalyzed reactions of truncated substrates d-xylonate or d-xylose. These and earlier results from studies on ß-phosphoglucomutase, triosephosphate isomerase, and glycerol 3-phosphate dehydrogenase define a cluster of six enzymes that catalyze reactions in glycolysis or of glycolytic intermediates, and which utilize substrate dianion binding energy for enzyme activation. Dianion-driven conformational changes, which convert flexible open proteins to tight protein cages for the phosphorylated substrate, have been thoroughly documented for five of these six enzymes. The clustering of metabolic enzymes which couple phosphodianion-driven conformational changes to enzyme activation suggests that this catalytic motif has been widely propagated in the proteome.

Perioperative Infection Transmission: the Role of the Anesthesia Provider in Infection Control and Healthcare-Associated Infections.

PURPOSE OF REVIEW: This review aims to highlight key factors in the perioperative environment that contribute to transmission of infectious pathogens, leading to healthcare-associated infection. This knowledge will provide anesthesia providers the tools to optimize preventive measures, with the goal of improved patient and provider safety. RECENT FINDINGS: Over the past decade, much has been learned about the epidemiology of perioperative pathogen transmission. Patients, providers, and the environment serve as reservoirs of origin that contribute to infection development. Ongoing surveillance of pathogen transmission among these reservoirs is essential to ensure effective perioperative infection prevention. SUMMARY: Recent work has proven the efficacy of a strategic approach for perioperative optimization of hand hygiene, environmental cleaning, patient decolonization, and intravascular catheter design and handling improvement protocols. This work, proven to generate substantial reductions in surgical site infections, can also be applied to aide prevention of SARS-CoV-2 spread in the COVID-19 era.

Inverse Solvent Isotope Effects in Enzyme-Catalyzed Reactions.

Solvent isotope effects have long been used as a mechanistic tool for determining enzyme mechanisms. Most commonly, macroscopic rate constants such as kcat and kcat/Km are found to decrease when the reaction is performed in D2O for a variety of reasons including the transfer of protons. Under certain circumstances, these constants are found to increase, in what is termed an inverse solvent kinetic isotope effect (SKIE), which can be a diagnostic mechanistic feature. Generally, these phenomena can be attributed to an inverse solvent equilibrium isotope effect on a rapid equilibrium preceding the rate-limiting step(s). This review surveys inverse SKIEs in enzyme-catalyzed reactions by assessing their underlying origins in common mechanistic themes. Case studies for each category are presented, and the mechanistic implications are put into context. It is hoped that readers may find the illustrative examples valuable in planning and interpreting solvent isotope effect experiments.

Subanesthetic ketamine infusions for the management of pediatric pain in non-critical care settings: An observational analysis.

BACKGROUND: Guidelines issued by the American Society of Regional Anesthesia and Pain Medicine suggest that ketamine infusions for acute pain management are advantageous as a primary treatment or as an opioid adjunct. Despite significant data regarding its use in adult patients, there remains a paucity of information related to its quality and side effect profile in pediatrics and how it can be effectively used. We aimed to summarize our practice of utilizing ketamine for pediatric pain management in non-critical care settings. METHODS: Patients aged 0-21 years receiving low-dose ketamine infusions (≤0.3 mg/kg/hour) in inpatient care units over five years were retrospectively analyzed. Demographics, specific quality metrics, and side effects were quantified. RESULTS: About 172 patients received 270 subhypnotic ketamine infusions. The median duration of the infusions was 63.8 hours and 0.2 mg/kg/hour for the highest dose. The primary indication for ketamine was chronic pain exacerbation (83.3%). Despite similar opioid consumption, there was a significant reduction in mean verbal pain scores before (8.9 ± 1.9, P < .001) and after ketamine (6.5 ± 2.7, P < .001) use. Although there were 52 incidences of some side effect (neurologic excitability [10.4%]; over-sedation [7.4%]; rapid response team alerts [1.1%]), none resulted in termination of the infusion or escalations in care. CONCLUSION: Ketamine can effectively be used as part of a multimodal analgesic regimen in pediatric patients in non-critical care settings. Our five-year experience using low-dose ketamine infusions highlights an acceptable side effect profile, with no attributable escalations in care or serious adverse events.

Predictors of transfusion outcomes in pediatric complex cranial vault reconstruction: a multicentre observational study from the Pediatric Craniofacial Collaborative Group.

PURPOSE: Pediatric patients undergoing complex cranial vault reconstruction (CCVR) are at risk of significant perioperative blood loss requiring blood product transfusion. Minimizing allogeneic blood product transfusion is an important goal because of the associated risks and cost. The impact of patient and surgical variables on transfusion is unknown in this population. Our primary aim was to examine relationships between demographic and perioperative variables and blood product transfusion outcomes in CCVR. METHODS: The multicentre Pediatric Surgery Perioperative Registry was checked for children undergoing CCVR between June 2012 and September 2016. Univariable and multivariable analyses were performed examining patient, procedure, and blood conservation variables and their relationship to three outcomes: intraoperative red blood cell-containing product (RBC-CP) transfusion, total perioperative blood donor exposures, and transfusion-free hospitalization. RESULTS: The registry search returned data from 1,814 cases. Age and surgical duration were the only variables significantly associated with all three outcomes studied. Predictors of reduced RBC-CP transfusion included lower American Society of Anesthesiologists (ASA) physical status and antifibrinolytic administration. Total cranial vault reconstruction, intraoperative vasoactive infusion, and presence of a tracheostomy predicted increased donor exposures. Increased body weight, higher preoperative hematocrit, and utilization of intraoperative cell saver and transfusion protocols were associated with transfusion-free hospitalization. CONCLUSION: Clinical factors associated with increased allogeneic blood product transfusion in pediatric CCVR include: age ≤ 24 months, ASA status ≥ III, preoperative anemia, prolonged surgical duration, lack of intraoperative antifibrinolytic use, lack of intraoperative cell saver use, and the lack of transfusion protocols.

RéSUMé: OBJECTIF: Les patients pédiatriques subissant une reconstruction complexe de la voûte crânienne courent un risque de pertes sanguines périopératoires importantes nécessitant la transfusion de produits sanguins. La minimisation de la transfusion de produits sanguins allogènes constitue un objectif majeur étant donné les risques et les coûts associés. L'impact des variables liées au patient et à la chirurgie sur la transfusion est inconnu dans cette population. Notre objectif principal était d'examiner les liens entre les variables démographiques et périopératoires, et les résultats des transfusions sanguines suite à une reconstruction complexe de la voûte crânienne. MéTHODE: Le Registre périopératoire multicentrique de chirurgie pédiatrique (Pediatric Surgery Perioperative Registry) a été consulté afin d'en extraire les dossiers de tous les enfants ayant subi une reconstruction complexe de la voûte crânienne entre juin 2012 et septembre 2016. Des analyses univariées et multivariées ont été réalisées et ont examiné les variables concernant les patients, l'intervention et la conservation du sang ainsi que les relations entre ces données et trois critères : la transfusion peropératoire de produits contenant des érythrocytes, l'exposition durant toute la période périopératoire aux dons de sang, et l'hospitalisation sans transfusion. RéSULTATS: L'examen du Registre a permis d'extraire les données de 1814 cas. L'âge et la durée de la chirurgie étaient les deux seules variables à afficher une association significative aux trois critères à l'étude. Les prédicteurs d'une transfusion réduite d'érythrocytes étaient un statut physique ASA (American Society of Anesthesiologists) plus bas et l'administration d'agents antifibrinolytiques. La reconstruction totale de la voûte crânienne, la perfusion peropératoire d'agents vasoactifs et la présence d'une trachéostomie constituaient des prédicteurs d'exposition plus importante aux dons de sang. Un poids corporel accru, un hématocrite préopératoire plus élevé et l'utilisation de systèmes d'autotransfusion peropératoire et de protocoles de transfusion étaient associés à une hospitalisation sans transfusion. CONCLUSION: Les facteurs cliniques associés à une augmentation des transfusions de produits sanguins allogènes dans les cas de reconstruction complexe de la voûte crânienne chez l'enfant sont : un âge ≤ 24 mois, un statut ASA ≥ III, une anémie préopératoire, la durée prolongée de la chirurgie, l'absence d'utilisation peropératoire d'antifibrinolytiques, l'absence d'utilisation de systèmes d'autotransfusion peropératoire, et l'absence de protocoles de transfusion.

Endoscopic Versus Open Repair for Craniosynostosis in Infants Using Propensity Score Matching to Compare Outcomes: A Multicenter Study from the Pediatric Craniofacial Collaborative Group.

BACKGROUND: The North American Pediatric Craniofacial Collaborative Group (PCCG) established the Pediatric Craniofacial Surgery Perioperative Registry to evaluate outcomes in infants and children undergoing craniosynostosis repair. The goal of this multicenter study was to utilize this registry to assess differences in blood utilization, intensive care unit (ICU) utilization, duration of hospitalization, and perioperative complications between endoscopic-assisted (ESC) and open repair in infants with craniosynostosis. We hypothesized that advantages of ESC from single-center studies would be validated based on combined data from a large multicenter registry. METHODS: Thirty-one institutions contributed data from June 2012 to September 2015. We analyzed 1382 infants younger than 12 months undergoing open (anterior and/or posterior cranial vault reconstruction, modified-Pi procedure, or strip craniectomy) or endoscopic craniectomy. The primary outcomes included transfusion data, ICU utilization, hospital length of stay, and perioperative complications; secondary outcomes included anesthesia and surgical duration. Comparison of unmatched groups (ESC: N = 311, open repair: N = 1071) and propensity score 2:1 matched groups (ESC: N = 311, open repair: N = 622) were performed by conditional logistic regression analysis. RESULTS: Imbalances in baseline age and weight are inherent due to surgical selection criteria for ESC. Quality of propensity score matching in balancing age and weight between ESC and open groups was assessed by quintiles of the propensity scores. Analysis of matched groups confirmed significantly reduced utilization of blood (26% vs 81%, P < .001) and coagulation (3% vs 16%, P < .001) products in the ESC group compared to the open group. Median blood donor exposure (0 vs 1), anesthesia (168 vs 248 minutes) and surgical duration (70 vs 130 minutes), days in ICU (0 vs 2), and hospital length of stay (2 vs 4) were all significantly lower in the ESC group (all P < .001). Median volume of red blood cell administered was significantly lower in ESC (19.6 vs 26.9 mL/kg, P = .035), with a difference of approximately 7 mL/kg less for the ESC (95% confidence interval for the difference, 3-12 mL/kg), whereas the median volume of coagulation products was not significantly different between the 2 groups (21.2 vs 24.6 mL/kg, P = .73). Incidence of complications including hypotension requiring treatment with vasoactive agents (3% vs 4%), venous air embolism (1%), and hypothermia, defined as <35°C (22% vs 26%), was similar between the 2 groups, whereas postoperative intubation was significantly higher in the open group (2% vs 10%, P < .001). CONCLUSIONS: This multicenter study of ESC versus open craniosynostosis repair represents the largest comparison to date. It demonstrates striking advantages of ESC for young infants that may result in improved clinical outcomes, as well as increased safety.

Utilization of a Text and Translation Application for Communication With a Foreign Deaf Family: A Call for Validation of This Technology-A Case Report.

Effective communication with patients is essential to quality care. Obviously, language barriers significantly impact this and can increase the risk of poor patient outcomes. Smartphones and mobile health technology are valuable resources that are beginning to break down language barriers in health care. We present a case of a challenging language barrier where successful perioperative communication was achieved using mobile technology. Although quite beneficial, use of technology that is not validated exposes providers to unnecessary medicolegal risk. We hope to highlight the need for validation of such technology to ensure that these tools are an effective way to accurately communicate with patients in the perioperative setting.

Perioperative considerations for the food-allergic pediatric patient.

Patients with a history of food allergy and food intolerance are common in the pediatric population and are encountered frequently in the perioperative setting by pediatric anesthesiologists. Perioperatively, food allergy can present on a spectrum ranging from minor acute urticaria to more severe hypovolemia and anaphylactic shock. Allergy to foods including fruits, fish, egg, soy, and peanut are most concerning for their potential to cross-react with perioperative medications. There is little in the anesthesia literature that focuses on the perioperative management of children with food allergies. This educational review will provide a brief overview of classic immunoglobulin E (IgE)-mediated food allergies, less common non-IgE food allergies, and present perioperative considerations for these patients. An audio summary of this topic is included as Supplementary Audio S1.

Perioperative Outcomes and Management in Pediatric Complex Cranial Vault Reconstruction: A Multicenter Study from the Pediatric Craniofacial Collaborative Group.

BACKGROUND: The Pediatric Craniofacial Collaborative Group established the Pediatric Craniofacial Surgery Perioperative Registry to elucidate practices and outcomes in children with craniosynostosis undergoing complex cranial vault reconstruction and inform quality improvement efforts. The aim of this study is to determine perioperative management, outcomes, and complications in children undergoing complex cranial vault reconstruction across North America and to delineate salient features of current practices. METHODS: Thirty-one institutions contributed data from June 2012 to September 2015. Data extracted included demographics, perioperative management, length of stay, laboratory results, and blood management techniques employed. Complications and outlier events were described. Outcomes analyzed included total blood donor exposures, intraoperative and perioperative transfusion volumes, and length of stay outcomes. RESULTS: One thousand two hundred twenty-three cases were analyzed: 935 children aged less than or equal to 24 months and 288 children aged more than 24 months. Ninety-five percent of children aged less than or equal to 24 months and 79% of children aged more than 24 months received at least one transfusion. There were no deaths. Notable complications included cardiac arrest, postoperative seizures, unplanned postoperative mechanical ventilation, large-volume transfusion, and unplanned second surgeries. Utilization of blood conservation techniques was highly variable. CONCLUSIONS: The authors present a comprehensive description of perioperative management, outcomes, and complications from a large group of North American children undergoing complex cranial vault reconstruction. Transfusion remains the rule for the vast majority of patients. The occurrence of numerous significant complications together with large variability in perioperative management and outcomes suggest targets for improvement.

Hand hygiene knowledge and perceptions among anesthesia providers.

BACKGROUND: Health care worker compliance with hand hygiene guidelines is an important measure for health care-associated infection prevention, yet overall compliance across all health care arenas remains low. A correct answer to 4 of 4 structured questions pertaining to indications for hand decontamination (according to types of contact) has been associated with improved health care provider hand hygiene compliance when compared to those health care providers answering incorrectly for 1 or more questions. A better understanding of knowledge deficits among anesthesia providers may lead to hand hygiene improvement strategies. In this study, our primary aims were to characterize and identify predictors for hand hygiene knowledge deficits among anesthesia providers. METHODS: We modified this previously tested survey instrument to measure anesthesia provider hand hygiene knowledge regarding the 5 moments of hand hygiene across national and multicenter groups. Complete knowledge was defined by correct answers to 5 questions addressing the 5 moments for hand hygiene and received a score of 1. Incomplete knowledge was defined by an incorrect answer to 1 or more of the 5 questions and received a score of 0. We used a multilevel random-effects XTMELOGIT logistic model clustering at the respondent and geographic location for insufficient knowledge and forward/backward stepwise logistic regression analysis to identify predictors for incomplete knowledge. RESULTS: The survey response rates were 55.8% and 18.2% for the multicenter and national survey study groups, respectively. One or more knowledge deficits occurred with 81.6% of survey respondents, with the mean number of correct answers 2.89 (95% confidence interval, 2.78- 2.99). Failure of providers to recognize prior contact with the environment and prior contact with the patient as hand hygiene opportunities contributed to the low mean. Several cognitive factors were associated with a reduced risk of incomplete knowledge including providers responding positively to washing their hands after contact with the environment (odds ratio [OR] 0.23, 0.14-0.37, P < 0.001), disinfecting their environment during patient care (OR 0.54, 0.35-0.82, P = 0.004), believing that they can influence their colleagues (OR 0.43, 0.27-0.68, P < 0.001), and intending to adhere to guidelines (OR 0.56, 0.36-0.86, P = 0.008). These covariates were associated with an area under receiver operator characteristics curve of 0.79 (95% confidence interval, 0.74-0.83). CONCLUSIONS: Anesthesia provider knowledge deficits around to hand hygiene guidelines occur frequently and are often due to failure to recognize opportunities for hand hygiene after prior contact with contaminated patient and environmental reservoirs. Intraoperative hand hygiene improvement programs should address these knowledge deficits. Predictors for incomplete knowledge as identified in this study should be validated in future studies.

Juvenile nasopharyngeal angiofibroma: vascular determinates for operative complications and tumor recurrence.

OBJECTIVES/HYPOTHESIS: Operative complications and tumor recurrence in juvenile nasopharyngeal angiofibroma (JNA) are measurable and meaningful outcomes. This study aimed to assess the association of these two outcomes to various clinical indices and in particular, vascular determinates. STUDY DESIGN: Retrospective cohort study. METHODS: An 18-year retrospective chart review of an academic tertiary center was undertaken. Data from clinical notes, imaging studies, and arteriograms were analyzed. RESULTS: Thirty-seven male (mean age, 14.4 years) patients were included in the study. Tumor stages included: IA (three), IB (three), IIA (14), IIB (three), IIC (five), IIIA (five), and IIIB (four). Four complications (cerebrospinal fluid leak, cerebral vascular accident, and two transient ocular defects) occurred. Eight recurrences occurred within 24 months following surgery. Complications were associated with estimated intraoperative blood loss (EBL) (P = .045). Tumor recurrence was associated with feeding vessels from the contralateral internal carotid artery (ICA) (P = .017). EBL was significantly associated with surgical technique used. EBL, tumor stage, and tumor vascular supply were significantly associated with each other. CONCLUSIONS: Vascular factors were associated with JNA complication and tumor recurrence. EBL might affect complications, and contralateral ICA as a feeding vessel might affect recurrence. EBL was influenced by procedure choice and was interrelated to size and vascular supply of the tumor. This study bolsters the need to decrease intraoperative blood loss by preoperative embolization and use of endoscopic removal techniques. Furthermore, when branches of the ICA are found to be feeding vessels, greater surgical attention for a dry surgical field is encouraged.

Multiple reservoirs contribute to intraoperative bacterial transmission.

BACKGROUND: Intraoperative stopcock contamination is a frequent event associated with increased patient mortality. In the current study we examined the relative contributions of anesthesia provider hands, the patient, and the patient environment to stopcock contamination. Our secondary aims were to identify risk factors for stopcock contamination and to examine the prior association of stopcock contamination with 30-day postoperative infection and mortality. Additional microbiological analyses were completed to determine the prevalence of bacterial pathogens within intraoperative bacterial reservoirs. Pulsed-field gel electrophoresis was used to assess the contribution of reservoir bacterial pathogens to 30-day postoperative infections. METHODS: In a multicenter study, stopcock transmission events were observed in 274 operating rooms, with the first and second cases of the day in each operating room studied in series to identify within- and between-case transmission events. Reservoir bacterial cultures were obtained and compared with stopcock set isolates to determine the origin of stopcock contamination. Between-case transmission was defined by the isolation of 1 or more bacterial isolates from the stopcock set of a subsequent case (case 2) that were identical to reservoir isolates from the preceding case (case 1). Within-case transmission was defined by the isolation of 1 or more bacterial isolates from a stopcock set that were identical to bacterial reservoirs from the same case. Bacterial pathogens within these reservoirs were identified, and their potential contribution to postoperative infections was evaluated. All patients were followed for 30 days postoperatively for the development of infection and all-cause mortality. RESULTS: Stopcock contamination was detected in 23% (126 out of 548) of cases with 14 between-case and 30 within-case transmission events confirmed. All 3 reservoirs contributed to between-case (64% environment, 14% patient, and 21% provider) and within-case (47% environment, 23% patient, and 30% provider) stopcock transmission. The environment was a more likely source of stopcock contamination than provider hands (relative risk [RR] 1.91, confidence interval [CI] 1.09 to 3.35, P = 0.029) or patients (RR 2.56, CI 1.34 to 4.89, P = 0.002). Hospital site (odds ratio [OR] 5.09, CI 2.02 to 12.86, P = 0.001) and case 2 (OR 6.82, CI 4.03 to 11.5, P < 0.001) were significant predictors of stopcock contamination. Stopcock contamination was associated with increased mortality (OR 58.5, CI 2.32 to 1477, P = 0.014). Intraoperative bacterial contamination of patients and provider hands was linked to 30-day postoperative infections. CONCLUSIONS: Bacterial contamination of patients, provider hands, and the environment contributes to stopcock transmission events, but the surrounding patient environment is the most likely source. Stopcock contamination is associated with increased patient mortality. Patient and provider bacterial reservoirs contribute to 30-day postoperative infections. Multimodal programs designed to target each of these reservoirs in parallel should be studied intensely as a comprehensive approach to reducing intraoperative bacterial transmission.

Micelle and solvent relaxation in aqueous sodium dodecylsulfate solutions.

Dielectric spectra have been measured for aqueous sodium dodecylsulfate (SDS) solutions up to 0.1 mol L-1 at 25 degrees C over the frequency range 0.005 < or = nu GHz-1 < or = 89. The spectra exhibit two relaxation processes at approximately 0.03 GHz and 0.2 GHz associated with the presence of micelles in addition to the dominant solvent relaxation process at approximately 18 GHz and a small contribution at approximately 1.8 GHz due to H2O molecules hydrating the micelles. Detailed analysis reveals that the micelles bind 20 water molecules per SDS unit, but not as strongly as trimethylalkylammonium halide surfactants do. The relaxation times and amplitudes of both micelle relaxation processes can be simultaneously analysed with the theory of Grosse, yielding the effective volume of a SDS unit in the micelle and the lateral diffusion coefficient of the bound counterions. The findings of this investigation fully corroborate recent molecular dynamics simulations on structure and dynamics of SDS micelles.