Enhanced recovery after cardiac surgery: A literature review

Enhanced recovery after cardiac surgery (ERACS) represents a constellation of evidence-based peri-operative methods aimed to reduce the physiological and psychological stress patients experience after cardiac surgery, with the primary objective of providing an expedited recovery to pre-operative functional status. The method involves pre-operative, intra-operative, and post-operative interventions as well as direct patient engagement to be successful. Numerous publications in regard to the benefits of enhanced recovery have been presented, including decreased post-operative complications, shortened length of stay, decreased overall healthcare costs, and higher patient satisfaction. Implementing an ERACS program undeniably requires a culture change, a methodical shift in the approach of these patients that ultimately allows the team to achieve the aforementioned goals; therefore, team-building, planning, and anticipation of obstacles should be expected.

Opioid-Free Recovery After Hernia Repair with HTX-011 as the Foundation of a Non-Opioid, Multimodal Analgesia Regimen in a Real-World Setting: A Randomized, Open-Label Study

INTRODUCTION

Helping Opioid Prescription Elimination (HOPE) is a project designed to provide surgeons with practical, real-world solutions to effectively manage postoperative pain and eliminate the need for opioids using HTX-011 (extended-release bupivacaine/low-dose meloxicam). In phase 3 herniorrhaphy and bunionectomy studies, HTX-011 without multimodal analgesia (MMA) was superior to bupivacaine hydrochloride in reducing pain and opioid consumption. Here, we examine the HOPE Hernia-1 study, which was designed to compare alternating ibuprofen/acetaminophen with concurrent use as part of an HTX-011-based non-opioid MMA regimen in patients undergoing herniorrhaphy and to evaluate the effectiveness of a personalized opioid prescription algorithm.

METHODS

Patients undergoing outpatient open inguinal herniorrhaphy with intraoperative administration of HTX-011 (300 mg bupivacaine/9 mg meloxicam) were randomly assigned to receive a scheduled oral regimen of ibuprofen plus acetaminophen, either taken together every 6 hours or alternating every 3 hours, for 5 days following surgery, while awake. Based on the opioid prescription algorithm evaluated here, patients could receive an oxycodone prescription upon discharge only if they had a numeric rating scale pain score of ≥ 6 at discharge and/or had received a postoperative rescue opioid.

RESULTS

The majority of patients did not require an opioid prescription through 2 weeks following surgery, and this was similar between cohorts (alternating MMA, 89.1%; concurrent MMA, 93.6%). Patient satisfaction was high for both regimens, and 95% of patients had an opioid-free recovery. No patient discharged without a prescription called back to request one. Treatment was well tolerated, without evidence of nonsteroidal anti-inflammatory drug-related toxicity.

CONCLUSIONS

HTX-011, used with over-the-counter products ibuprofen/acetaminophen and personalized opioid prescription algorithm in a real-world environment, has the potential to reduce opioid use and opioid prescriptions after herniorrhaphy without compromising patient satisfaction.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03237481.

Modeling the Cost Savings of Continuous Pulse Oximetry and Capnography Monitoring of United States General Care Floor Patients Receiving Opioids Based on the PRODIGY Trial

INTRODUCTION

Despite the high incidence of respiratory depression on the general care floor and evidence that continuous monitoring improves patient outcomes, the cost-benefit of continuous pulse oximetry and capnography monitoring of general care floor patients remains unknown. This study modeled the cost and length of stay savings, investment break-even point, and likelihood of cost savings for continuous pulse oximetry and capnography monitoring of general care floor patients at risk for respiratory depression.

METHODS

A decision tree model was created to compare intermittent pulse oximetry versus continuous pulse oximetry and capnography monitoring. The model utilized costs and outcomes from the PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial, and was applied to a modeled cohort of 2447 patients receiving opioids per median-sized United States general care floor annually.

RESULTS

Continuous pulse oximetry and capnography monitoring of high-risk patients is projected to reduce annual hospital cost by $535,531 and cumulative patient length of stay by 103 days. A 1.5% reduction in respiratory depression would achieve a break-even investment point and justify the investment cost. The probability of cost saving is ≥ 80% if respiratory depression is decreased by ≥ 17%. Expansion of continuous monitoring to high- and intermediate-risk patients, or to all patients, is projected to reach a break-even point when respiratory depression is reduced by 2.5% and 3.5%, respectively, with a ≥ 80% probability of cost savings when respiratory depression decreases by ≥ 27% and ≥ 31%, respectively.

CONCLUSION

Compared to intermittent pulse oximetry, continuous pulse oximetry and capnography monitoring of general care floor patients receiving opioids has a high chance of being cost-effective.

TRIAL REGISTRATION

www.clinicaltrials.gov , Registration ID: NCT02811302.

Opioid-induced respiratory depression increases hospital costs and length of stay in patients recovering on the general care floor

BACKGROUND

Opioid-induced respiratory depression is common on the general care floor. However, the clinical and economic burden of respiratory depression is not well-described. The PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial created a prediction tool to identify patients at risk of respiratory depression. The purpose of this retrospective sub-analysis was to examine healthcare utilization and hospital cost associated with respiratory depression.

METHODS

One thousand three hundred thirty-five patients (N = 769 United States patients) enrolled in the PRODIGY trial received parenteral opioids and underwent continuous capnography and pulse oximetry monitoring. Cost data was retrospectively collected for 420 United States patients. Differences in healthcare utilization and costs between patients with and without ≥1 respiratory depression episode were determined. The impact of respiratory depression on hospital cost per patient was evaluated using a propensity weighted generalized linear model.

RESULTS

Patients with ≥1 respiratory depression episode had a longer length of stay (6.4 ± 7.8 days vs 5.0 ± 4.3 days, p = 0.009) and higher hospital cost ($21,892 ± $11,540 vs $18,206 ± $10,864, p = 0.002) compared to patients without respiratory depression. Patients at high risk for respiratory depression, determined using the PRODIGY risk prediction tool, who had ≥1 respiratory depression episode had higher hospital costs compared to high risk patients without respiratory depression ($21,948 ± $9128 vs $18,474 ± $9767, p = 0.0495). Propensity weighted analysis identified 17% higher costs for patients with ≥1 respiratory depression episode (p = 0.007). Length of stay significantly increased total cost, with cost increasing exponentially for patients with ≥1 respiratory depression episode as length of stay increased.

CONCLUSIONS

Respiratory depression on the general care floor is associated with a significantly longer length of stay and increased hospital costs. Early identification of patients at risk for respiratory depression, along with early proactive intervention, may reduce the incidence of respiratory depression and its associated clinical and economic burden.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT02811302 .

Prediction of Opioid-Induced Respiratory Depression on Inpatient Wards Using Continuous Capnography and Oximetry: An International Prospective, Observational Trial

BACKGROUND

Opioid-related adverse events are a serious problem in hospitalized patients. Little is known about patients who are likely to experience opioid-induced respiratory depression events on the general care floor and may benefit from improved monitoring and early intervention. The trial objective was to derive and validate a risk prediction tool for respiratory depression in patients receiving opioids, as detected by continuous pulse oximetry and capnography monitoring.

METHODS

PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) was a prospective, observational trial of blinded continuous capnography and oximetry conducted at 16 sites in the United States, Europe, and Asia. Vital signs were intermittently monitored per standard of care. A total of 1335 patients receiving parenteral opioids and continuously monitored on the general care floor were included in the analysis. A respiratory depression episode was defined as respiratory rate ≤5 breaths/min (bpm), oxygen saturation ≤85%, or end-tidal carbon dioxide ≤15 or ≥60 mm Hg for ≥3 minutes; apnea episode lasting >30 seconds; or any respiratory opioid-related adverse event. A risk prediction tool was derived using a multivariable logistic regression model of 46 a priori defined risk factors with stepwise selection and was internally validated by bootstrapping.

RESULTS

One or more respiratory depression episodes were detected in 614 (46%) of 1335 general care floor patients (43% male; mean age, 58 ± 14 years) continuously monitored for a median of 24 hours (interquartile range [IQR], 17-26). A multivariable respiratory depression prediction model with area under the curve of 0.740 was developed using 5 independent variables: age ≥60 (in decades), sex, opioid naivety, sleep disorders, and chronic heart failure. The PRODIGY risk prediction tool showed significant separation between patients with and without respiratory depression (P < .001) and an odds ratio of 6.07 (95% confidence interval [CI], 4.44-8.30; P < .001) between the high- and low-risk groups. Compared to patients without respiratory depression episodes, mean hospital length of stay was 3 days longer in patients with ≥1 respiratory depression episode (10.5 ± 10.8 vs 7.7 ± 7.8 days; P < .0001) identified using continuous oximetry and capnography monitoring.

CONCLUSIONS

A PRODIGY risk prediction model, derived from continuous oximetry and capnography, accurately predicts respiratory depression episodes in patients receiving opioids on the general care floor. Implementation of the PRODIGY score to determine the need for continuous monitoring may be a first step to reduce the incidence and consequences of respiratory compromise in patients receiving opioids on the general care floor.

Succinylcholine Use and Dantrolene Availability for Malignant Hyperthermia Treatment: Database Analyses and Systematic Review

BACKGROUND

Although dantrolene effectively treats malignant hyperthermia (MH), discrepant recommendations exist concerning dantrolene availability. Whereas Malignant Hyperthermia Association of the United States guidelines state dantrolene must be available within 10 min of the decision to treat MH wherever volatile anesthetics or succinylcholine are administered, a Society for Ambulatory Anesthesia protocol permits Class B ambulatory facilities to stock succinylcholine for airway rescue without dantrolene. The authors investigated (1) succinylcholine use rates, including for airway rescue, in anesthetizing/sedating locations; (2) whether succinylcholine without volatile anesthetics triggers MH warranting dantrolene; and (3) the relationship between dantrolene administration and MH morbidity/mortality.

METHODS

The authors performed focused analyses of the Multicenter Perioperative Outcomes Group (2005 through 2016), North American MH Registry (2013 through 2016), and Anesthesia Closed Claims Project (1970 through 2014) databases, as well as a systematic literature review (1987 through 2017). The authors used difficult mask ventilation (grades III and IV) as a surrogate for airway rescue. MH experts judged dantrolene treatment. For MH morbidity/mortality analyses, the authors included U.S. and Canadian cases that were fulminant or scored 20 or higher on the clinical grading scale and in which volatile anesthetics or succinylcholine were given.

RESULTS

Among 6,368,356 queried outcomes cases, 246,904 (3.9%) received succinylcholine without volatile agents. Succinylcholine was used in 46% (n = 710) of grade IV mask ventilation cases (median dose, 100 mg, 1.2 mg/kg). Succinylcholine without volatile anesthetics triggered 24 MH cases, 13 requiring dantrolene. Among 310 anesthetic-triggered MH cases, morbidity was 20 to 37%. Treatment delay increased complications every 10 min, reaching 100% with a 50-min delay. Overall mortality was 1 to 10%; 15 U.S. patients died, including 4 after anesthetics in freestanding facilities.

CONCLUSIONS

Providers use succinylcholine commonly, including during difficult mask ventilation. Succinylcholine administered without volatile anesthetics may trigger MH events requiring dantrolene. Delayed dantrolene treatment increases the likelihood of MH complications. The data reported herein support stocking dantrolene wherever succinylcholine or volatile anesthetics may be used.

Inter-Rater Reliability and Reception of the Michigan Opioid Safety Score

PURPOSE

The Michigan Opioid Safety Score (MOSS) combines health risk, respiratory rate, and sedation measurement to guide safe opioid administration. This study was designed to assess reliability and nursing acceptance of the MOSS tool.

DESIGN

Cross-sectional survey.

METHODS

Nurses without prior exposure to the tool were asked to participate in an online survey. In part I, raters utilized the MOSS to answer questions based on four fictional case scenarios. In part II, anonymous opinion of the tool was queried.

FINDING

Participants correctly scored 58.1% of patient scenarios, while appropriate clinical action was 80.5%. The intraclass correlation coefficient was 0.83. In terms of opinion, a majority of raters agreed the tool positively impacted patient safety (59.2%), improved confidence in opioid therapy (59.2%), and was easy to use (53%).

CONCLUSIONS

Participants interpreted case scenarios with excellent inter-rater reliability and had a generally positive opinion. These study findings suggest the MOSS is a reliable safety instrument.

AT III Barcelona: A Familial Quantitative-Qualitative AT III Deficiency

A quantitative and qualitative deficiency of antithrombin III (AT III) was found in four members of a Spanish family with thrombotic tendency. In all affected members, levels of AT III antigen and activity (heparin cofactor activity) were reduced to 50% of the normal range. When crossed immunoelectrophoresis (CIE) was performed in the presence of heparin, an abnormal slow-moving peak was found. Crossed immunoelectrofocusing (CIEF) from normal and affected individuals showed that normal AT III migrated between pH 4.9–5.3 while the AT III under study was asymetrically distributed between two pH ranges: 4.9–5.3 and 4.6–4.8. Affinity adsorption of affected members’ plasma to heparin-sepharose beads revealed one population of AT III in the supernatant corresponding to the abnormal AT III, devoid of heparin cofactor activity and showing a peak between pH range: 4.6–4.8 in CIEF.

Our data supports the view that a quantitative-qualitative deficiency was present in the heterozygous state in all the affected family members. Both normal and abnormal ATIII were present in plasma of the affected individuals. This abnormal ATIII was characterized by a lack of affinity for heparin. This familial ATIII deficiency was named ATIII Barcelona.

Catalytic activity dependence on morphological properties of acidic ion-exchange resins for the simultaneous ETBE and TAEE liquid-phase synthesis

Resin acid capacity and specific volume of the swollen polymer are the key properties that determine its catalytic activity.

Kinematics and Dynamics of a New 16 DOF Humanoid Biped Robot with Active Toe Joint

Humanoid biped robots are typically complex in design, having numerous Degrees-of-Freedom (DOF) due to the ambitious goal of mimicking the human gait. The paper proposes a new architecture for a biped robot with seven DOF per each leg and one DOF corresponding to the toe joint. Furthermore, this work presents close equations for the forward and inverse kinematics by dividing the walking gait into the Sagittal and Frontal planes. This paper explains the mathematical model of the dynamics equations for the legs into the Sagittal and Frontal planes by further applying the principle of Lagrangian dynamics. Finally, a control approach using a PD control law with gravity compensation was recurred in order to control the desired trajectories and finding the required torque by the joints. The paper contains several simulations and numerical examples to prove the analytical results, using SimMechanics of MATLAB toolbox and SolidWorks to verify the analytical results.

Erratum to: Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

[This corrects the article DOI: 10.1186/s13017-016-0089-y.].

Simulating the activation, contraction and movement of skeletal muscles using the bidomain model

A simulation of the muscle activation, contraction and movement is here presented. This system was developed based on the Bidomain mathematical model of the electrical propagation in muscles. This study shows an electrical stimuli input to a muscle and how this behave. The comparison between healthy subject and patient with muscle activation impairment is depicted, depending on whether the signal reaches a threshold. A 3D model of a bicep muscle and a forearm bone connected was constructed using OpenGL. This platform could be used for development of controllers for biomechatronic systems in future works. This kind of bioinspired model could be used for a better understanding of the neuromotor system.

Erratum to: 'Prophylaxis and management of postoperative nausea and vomiting in enhanced recovery protocols'

[This corrects the article DOI: 10.1186/s13741-016-0029-0.].

Prophylaxis and management of postoperative nausea and vomiting in enhanced recovery protocols: Expert Opinion statement from the American Society for Enhanced Recovery (ASER)

International experience and evidence-based practices have shown that reduction in variability through use of protocolized perioperative care improves surgical outcomes and reduces costs to patients and healthcare systems. In this series of Expert Opinions, we provide consensus recommendations for the various components of perioperative care to aid with the development of enhanced recovery after surgery protocols.

Novel compliant actuator for wearable robotics applications

In the growing fields of wearable robotics, rehabilitation robotics, prosthetics, and walking robots, variable impedance and force actuators are being designed and implemented because of their ability to dynamically modulate the intrinsic viscoelastic properties such as stiffness and damping. This modulation is crucial to achieve an efficient and safe human-robot interaction that could lead to electronically generate useful emergent dynamical behaviors. In this work we propose a novel actuation system in which is implemented a control scheme based on equilibrium forces for an active joint capable to provide assistance/resistance as needed and also achieve minimal mechanical impedance when tracking the movement of the user limbs. The actuation system comprises a DC motor with a built in speed reducer, two force-sensing resistors (FSR), a mechanism which transmits to the FSRs the torque developed in the joint and a controller which regulate the amount of energy that is delivered to the DC motor. The proposed system showed more impedance reduction, by the effect of the controlled contact forces, compared with the ones in the reviewed literature.

Isotopic and hydrogeochemical characterization of high-altitude karst aquifers in complex geological settings. The Ordesa and Monte Perdido National Park (Northern Spain) case study

The Ordesa and Monte Perdido National Park, located in the Southern Pyrenees, constitutes the highest karst system in Western Europe. No previous studies regarding its geochemical and isotopic groundwater characterization are available in this area. This work presents the results of field and sampling campaigns carried out between July 2007 and September 2013. The groundwater presents high calcium bicarbonate contents due to the occurrence of upper Cretaceous and lower Paleocene-Eocene carbonate materials in the studied area. Other relevant processes include dissolution of anhydrite and/or gypsum and incongruent dissolution of Mg-limestone and dolomite. The water stable isotopes (δ(18)O, δ(2)H) show that the oceanic fronts from the Atlantic Ocean are responsible for the high levels of precipitation. In autumn, winter, and spring, a deuterium excess is found in the recharge water, which could be related to local atmospheric transport of low-altitude snow sublimation vapour and its later condensation on the snow surface at higher altitude, where recharge is mostly produced. The recharge zones are mainly between 2500m and 3200ma.s.l. The tritium content of the water suggests short groundwater transit times. The isotopic composition of dissolved sulphate points to the existence of regional fluxes mixed with local discharge in some of the springs. This work highlights the major role played by the altitude difference between the recharge and discharge zones in controlling the chemistry and the vertical variability of the isotopic composition in high-altitude karst aquifers.

Assessing carbon and nitrogen removal in a novel anoxic-aerobic cyanobacterial-bacterial photobioreactor configuration with enhanced biomass sedimentation

The carbon and nitrogen removal potential of an innovative anoxic-aerobic photobioreactor configuration operated with both internal and external recyclings was evaluated under different cyanobacterial-bacterial sludge residence times (9-31 days) during the treatment of wastewaters with low C/N ratios. Under optimal operating conditions, the two-stage photobioreactor was capable of providing organic carbon and nitrogen removals over 95% and 90%, respectively. The continuous biomass recycling from the settler resulted in the enrichment and predominance of rapidly-settling cyanobacterial-bacterial flocs and effluent suspended solid concentrations lower than 35 mg VSS L(-1). These flocs exhibited sedimentation rates of 0.28-0.42 m h(-1) but sludge volumetric indexes of 333-430 ml/g. The decoupling between the hydraulic retention time and sludge retention time mediated by the external recycling also avoided the washout of nitrifying bacteria and supported process operation at biomass concentrations of 1000-1500 mg VSS L(-1). The addition of additional NaHCO3 to the process overcame the CO2 limitation resulting from the intense competition for inorganic carbon between cyanobacteria and nitrifying bacteria in the photobioreactor, which supported the successful implementation of a nitrification-denitrification process. Unexpectedly, this nitrification-denitrification process occurred both simultaneously in the photobioreactor alone (as a result of the negligible dissolved oxygen concentrations) and sequentially in the two-stage anoxic-aerobic configuration with internal NO3(-)/NO2(-) recycling.

Casimir effect in swimmer suspensions

We show that the Casimir effect can emerge in microswimmer suspensions. In principle, two effects conspire against the development of Casimir effects in swimmer suspensions. First, at low Reynolds number, the force on any closed volume vanishes, but here the relevant effect is the drag by the flow produced by the swimmers, which can be finite. Second, the fluid velocity and the pressure are linear on the swimmer force dipoles, and averaging over the swimmer orientations would lead to a vanishing effect. However, being that the suspension is a discrete system, the noise terms of the coarse-grained equations depend on the density, which itself fluctuates, resulting in effective nonlinear dynamics. Applying the tools developed for other nonequilibrium systems to general coarse-grained equations for swimmer suspensions, the Casimir drag is computed on immersed objects, and it is found to depend on the correlation function between the rescaled density and dipolar density fields. By introducing a model correlation function with medium-range order, explicit expressions are obtained for the Casimir drag on a body. When the correlation length is much larger than the microscopic cutoff, the average drag is independent of the correlation length, with a range that depends only on the size of the immersed bodies.

The increases in potassium concentrations are greater with succinylcholine than with rocuronium-sugammadex in outpatient surgery: a randomized, multicentre trial

BACKGROUND

Succinylcholine provides rapid onset of neuromuscular blockade and short duration of action, but its administration may be associated with hyperkalemia. Rocuronium is not known to increase potassium concentration, has fast onset of activity, and can be rapidly reversed by sugammadex. This study evaluated changes in plasma potassium concentrations in patients randomized either to rocuronium followed by sugammadex reversal or to succinylcholine in ambulatory surgery.

METHODS

In this multicentre randomized active-controlled study, adult patients undergoing short surgical procedures in an outpatient setting received either rocuronium 0.6 mg·kg(-1) for intubation with sugammadex 4.0 mg·kg(-1) for reversal (n = 70) or succinylcholine 1.0 mg·kg(-1) with spontaneous recovery (n = 80). Blood potassium concentrations were assessed at baseline (before study drug administration) and at intervals up to 15 min after rocuronium, sugammadex, and succinylcholine.

RESULTS

At the primary endpoint, five minutes post-administration, the changes in potassium concentrations from baseline were significantly smaller in patients treated with rocuronium than in those given succinylcholine [mean (SD): -0.06 (0.32) vs 0.30 (0.34) mmol·L(-1), respectively; P < 0.0001]. At baseline, potassium concentrations were similar in both groups, but they were greater at two, five, ten, and 15 min after succinylcholine than after rocuronium (P < 0.0001) for all time points. After sugammadex administration, there were no significant changes in mean potassium concentration from the pre-rocuronium baseline. No adverse effects related to hyperkalemia were observed.

CONCLUSION

Succinylcholine was associated with a modest increase in potassium concentration; these changes were not seen after rocuronium or sugammadex (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00751179).

Active temperature and velocity correlations produced by a swimmer suspension

The agitation produced in a fluid by a suspension of microswimmers in the low Reynolds number limit is studied. In this limit, swimmers are modeled as force dipoles all with equal strength. The agitation is characterized by the active temperature defined, as in kinetic theory, as the mean square velocity, and by the equal-time spatial correlations. Considering the phase in which the swimmers are homogeneously and isotropically distributed in the fluid, it is shown that the active temperature and velocity correlations depend on a single scalar correlation function of the dipole-dipole correlation function. By making a simple medium-range order model, in which the dipole-dipole correlation function is characterized by a single correlation length k(0)(-1) it is possible to make quantitative predictions. It is found that the active temperature depends on the system size, scaling as L(4-d) at large correlation lengths L<<k(0)(-1), while in the opposite limit it saturates in three dimensions and diverges logarithmically with the system size in two dimensions. In three dimensions the velocity correlations decay as 1/r for small correlation lengths, while at large correlation lengths the transverse correlation function becomes negative at maximum separation r~L/2, an effect that disappears as the system increases in size.

Dynamical approach to the Casimir effect

Casimir forces can appear between intrusions placed in different media driven by several fluctuation mechanisms, either in equilibrium or out of it. Herein, we develop a general formalism to obtain such forces from the dynamical equations of the fluctuating medium, the statistical properties of the driving noise, and the boundary conditions of the intrusions (which simulate the interaction between the intrusions and the medium). As a result, an explicit formula for the Casimir force over the intrusions is derived. This formalism contains the thermal Casimir effect as a particular limit and generalizes the study of the Casimir effect to such systems through their dynamical equations, with no appeal to their Hamiltonian, if any exists. In particular, we study the Casimir force between two infinite parallel plates with Dirichlet or Neumann boundary conditions, immersed in several media with finite correlation lengths (reaction-diffusion system, liquid crystals, and two coupled fields with non-Hermitian evolution equations). The driving Gaussian noises have vanishing or finite spatial or temporal correlation lengths; in the first case, equilibrium is reobtained and finite correlations produce nonequilibrium dynamics. The results obtained show that, generally, nonequilibrium dynamics leads to Casimir forces, whereas Casimir forces are obtained in equilibrium dynamics if the stress tensor is anisotropic.

Cutaneous facial sinus tract of dental origin

Cutaneous sinus tract on the head and neck area in a child may originate from dental disease. A high degree of clinical suspicion and complementary tests are often needed, as the diagnosis is usually not straight forward. Anatomical correlation is also useful in tracing the affected tooth or teeth. We present the case of a boy with a facial sinus tract that originated from periapical abscesses of maxillary molars.

Segregation induced by inelasticity in a vibrofluidized granular mixture

We investigate the segregation of a dense binary mixture of granular particles that only differ in their restitution coefficient. The mixture is vertically vibrated in the presence of gravity. We find a partial segregation of the species, where most dissipative particles submerge in the less dissipative ones. The segregation occurs even if one type of the particles is elastic. In order to have a complete description of the system, we study the structure of the fluid at microscopic scale (few particle diameters). The density and temperature pair distribution functions show strong enhancements with respect to the equilibrium ones at the same density. In particular, there is an increase in the probability that the more inelastic particles group together in pairs (microsegregation). Microscopically the segregation is buoyancy driven, by the appearance of a dense and cold region around the more inelastic particles.

[Major closed-space bleeding in patients on anticoagulation with acenocoumarol (TAO) or non-fractionned heparin(HS): a case-control study]

OBJECTIVE

To study the characteristics of major bleeding episodes into a closed space (BCS) of patients under chronic anticoagulation with either unfractionated heparin (HS) or coumadin (CM), and to determine the relationship, if any, of anticoagulation parameters (INR, PT and PTT) values at the time of bleeding with the episode. Finally, to determine risk factors for BCS and mortality in this population.

METHODS

Descriptive epidemiology of all cases of BCS seen in our hospital from 1995 to 2000 was obtained through the records and follow up visits of all patients under anticoagulation (HS or CM) during this period. A matched case-control study to determine risk factors for BCS was carried out. Cases and controls (1:2) were matched for age, gender, anticoagulant treatment and indication for anticoagulation. Cases were patients with a BCS while on anticoagulation (HS OR CM). Controls were patients under anticoagulation (HS or CM) without any bleeding episode during the study period that had anticoagulation parameter values (INR, PT or PTT) determined the very same day than the cases.

RESULTS

During the study period, 225 patients under anticoagulation were prospectively followed (75 cases and 150 controls) amid a total of 1650 patients under anticoagulation, for a 4.5% prevalence of BCS. Reasons for anticoagulation were: atrial fibrillation in 79 (35.3%), valvular heart disease in 59 (25.9%), pulmonary embolism or deep venous thrombosis in 48 (21.4%), dilated cardiomyopathy in 26 (11.6%) and vascular cerebral stroke in 13 (5.8%). Mean age of cases was 70.5 (SD 9.5) years and 41 (55%) were women, values similar to the controls. At the time of BCS 39 patients were on CM and 36 on HS. The mean INR value in the CM group at the time of the episode of BCS was 5.3 (SD + 7.5) while the PTT value was 2,25 (SD 0.95) in the HS group. There was previous antecedent bleeding in 24 (32%) cases. The most common sites of BCS were: muscular (40%), CNS (30.6%), retroperitoneal (18,6%) and articular (10.6%). Muscular (abdominal or thoracic wall) and retroperitoneal BCS were higher in the HS group (10 and 12 in the HS group versus 5 and 2 in the CM group, respectively; p < 0.0001). In contrast, CNS bleeding was commoner in the CM group (20 in CM versus 3 in HS; p < 0.001). BCS related mortality rate was 14.6% (11/75) and higher in the CM group (p = 0.04). Comparative analysis of the case-control study revealed that anticoagulation values in the CM group at the time of bleeding were within the recommended range in 38.5% of cases vs. 75% of the controls (p < 0.001). Also, there were significant differences in mean INR values between cases and controls (5.3 + 7.5 vs. 2.6 + 0.9, p < 0.029) In the HS group no differences were present in PTT values at the time of bleeding between cases and controls. In BCS cases, a previous bleeding episode was more frequent than in the control group (32% versus 1.3%, p < 0.001). Likewise, mortality was higher in cases (18,6%) than in controls (11.4%), p = 0.01.

CONCLUSIONS

In our study, the majority of patients under anticoagulation with CM had INR values above the recommended range at the time of BCS, in contrast with those on HS that had a PTT within the therapeutic range at the time of the BCS. A previous bleeding episode was an independent risk factor for a BCS episode. Bleeding was a late complication in the CM group and frequently in the CNS, while BCS was more frequently associated with muscular or retroperitoneal sites in the HS treated group. BCS related mortality was 15%. Close monitoring of INR is crucial to minimize bleeding complications.

Generalized Casimir forces in nonequilibrium systems

In the present work, we propose a method to determine fluctuation-induced forces in nonequilibrium systems. These forces are the analog of the well-known Casimir forces, which were originally introduced in quantum field theory and later extended to the area of critical phenomena. The procedure starts from the observation that many nonequilibrium systems exhibit fluctuations with macroscopic correlation lengths, and the associated structure factors strongly depend on the wave vectors for long wavelengths; in some cases the correlations become long range, and the structure factors show algebraic divergences in the long-wavelength limit. The introduction of external bodies into such systems in general modifies the spectrum of these fluctuations, changing the value of the renormalized pressure, which becomes inhomogeneous. This inhomogeneous pressure leads to the appearance of a net force between the external bodies. It is shown that the force can be obtained from the knowledge of the structure factor of the homogeneous system. The mechanism is illustrated by means of a simple example: a reaction-diffusion equation, where the correlation function has a characteristic length. The role of this length in the Casimir force is elucidated.

A Randomized, Dose-Finding, Phase II Study of the Selective Relaxant Binding Drug, Sugammadex, Capable of Safely Reversing Profound Rocuronium-Induced Neuromuscular Block

BACKGROUND

The reversal of a deep neuromuscular blockade remains a significant clinical problem. Sugammadex, a modified gamma-cyclodextrin, encapsulates steroidal neuromuscular blocking drugs, promoting their rapid dissociation from nicotinic receptors. Sugammadex is the first drug that acts as a selective relaxant binding agent.

METHODS

We enrolled 50 patients into a Phase II dose-finding study of the efficacy and safety of sugammadex. Subjects, anesthetized with nitrous oxide and propofol, were randomized to one of two doses of rocuronium (0.6 or 1.2 mg/kg) and to one of five doses of sugammadex (0.5, 1.0, 2.0, 4.0, or 8.0 mg/kg). Neuromuscular monitoring was performed using the TOF Watch SX acceleromyograph. Recovery was defined as a train-of-four ratio > or =0.9. Sugammadex was administered during profound block when neuromuscular monitoring demonstrated a posttetanic count of one or two.

RESULTS

Reversal of neuromuscular block was obtained after administration of sugammadex in all but the lowest dose groups (0.5-1.0 mg/kg) where several subjects could not be adequately reversed. At the 2 mg/kg dose all patients were reversed with sugammadex, but there was significant variability (1.8-15.2 min). Patient variability decreased and speed of recovery increased in a dose-dependent manner. At the highest dose (8 mg/kg), mean recovery time was 1.2 min (range 0.8-2.1 min). No serious adverse events were reported during this trial.

CONCLUSIONS

Sugammadex was well tolerated and effective in rapidly reversing profound rocuronium-induced neuromuscular block. The mean time to recovery decreased with increasing doses. Profound rocuronium-induced neuromuscular block can be reversed successfully with sugammadex at doses >/=2 mg/kg.

The influence of radiotherapy technique and dose on the patterns of failure for mesothelioma patients following extrapleural pneumonectomy

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Background: Extrapleural pneumonectomy (EPP) is an effective treatment of pleural mesothelioma(MPM). We present a comparison of moderate-dose hemithoracic radiation (MDRT) to high-dose hemithoracic radiation (HDRT) following EPP for MPM. Methods: From 7/94 to 4/04, 39 pts underwent EPP and adjuvant radiotherapy (RT) at DFCI/BWH. From 1994–2002, MDRT, 30Gy to the hemithorax with boosts to the mediastinum or chest wall to 40–54 Gy was given, generally with concurrent chemotherapy (CT). Beginning in 2003, HDRT to 54 Gy as published by Yajnik et al (IJROBP 03’) was given with sequential CT. Results: Thirty-nine pts received RT following EPP. Median age was 59 yrs (range 44–77). Histology was epithelial in 25 (64%) pts and mixed/sarcomatoid in 14 (46%) pts. Twenty-four pts were treated with MDRT. 19 pts received concurrent platinum-based CT with MDRT. Three received cyclophosphomide, adriamycin and cisplatin (CDDP) CT prior to radiotherapy and 2 did not receive CT. 14 pts (39%) were treated with HDRT. 10/14 received sequential CDDP/gemcitabine, 4 received CDDP/pemetrexed and 1 patient received intraoperative CDDP. The median follow-up was 20 mos (range, 6–73 mos). Overall survival (OS) was 19 mos (95% CI, 14–24 mos). The median times to distant failure (DF) and local recurrence (LR) were 20 mos (95% CI, 14–26 mos) and 26 mos (95% CI, 16–36 mos), respectively. No significant differences in outcome between the two radiotherapy regimens were seen. One patient died of radiation-induced liver disease, one of pneumonitis and one of an MI. Four pts who received HDRT are alive and NED. On univariate and multivariate analysis mixed histology was predictive of DF and OS (p < .006; p < .004). Neither RT technique nor type of CT were predictive of LF, DF, or OS. The patterns of failure are in the table below. Conclusions: HDRT appears to limit in field local failures as compared to MDRT. Distant failure remains a significant challenge, with half of the patients experiencing distant failure.

[Table: see text]

No significant financial relationships to disclose.

Fluctuation-induced casimir forces in granular fluids

We numerically investigate the behavior of driven noncohesive granular media and find that two fixed large intruder particles, immersed in a sea of small particles, experience, in addition to a short-range depletion force, a long-range repulsive force. The observed long-range interaction is fluctuation-induced and we propose a mechanism similar to the Casimir effect that generates it: The hydrodynamic fluctuations are geometrically confined between the intruders, producing an unbalanced renormalized pressure. An estimation based on computing the possible Fourier modes explains the repulsive force and is in qualitative agreement with the simulations.

A Comparison of Bispectral Index and Entropy, or How to Misinterpret Both

Consciousness monitoring has become increasingly popular in general anesthesia cases, and a new technology has recently been introduced with potential advantages over the other available products. In this case report, we discuss a patient who was monitored simultaneously with Bispectral Index and Entropy and evaluate the differences between the two. More importantly, we emphasize the importance of vigilance when using new technologies and discuss the potential impact of lack of vigilance on patient outcome.

Evidence of chemical reactions between di- and poly-glycidyl ether resins and tannins isolated from Pinus radiata D. Don bark

This work evaluates the feasibility of reacting tannins isolated from Pinus radiata D. Don bark with epoxide resins of the diglycidyl and polyglycidyl ether type. To this end, gel times of aqueous tannin dispersions (40% w/w) with every one of nine selected resins (5% w/w), at previously established pH values (initial equal to 3.3, 4, 7 and 10), have been determined. Products of these reactions were analyzed by FT-IR spectroscopy, and the results were compared with those obtained from tannin-p-formaldehyde and (+)-catechin-p-formaldehyde systems, at the same pH values. Their mechanical properties were evaluated, by dynamic mechanical analysis, at two pH values (3.3 and 10). In general, it was concluded that tannin-epoxide resin systems behave similarly to tannin-paraformaldehyde systems, especially at basic pH values.

van der Waals normal form for a one-dimensional hydrodynamic model

Phase separation in a fluidized granular system is studied. We consider a one-dimensional hydrodynamic model that mimics a two-dimensional fluidized granular system with a vibrating wall and without gravity, which exhibits a phase separation. Close to the critical point, by means of an adiabatic elimination of the temperature, we deduce the van der Waals normal form, which is the equation that describes the slow dynamics of the system and predicts the qualitative behavior in different regions of parameters. This allows us to understand the origin of the effective viscosity and the spatial saturation at the onset of the bifurcation. The hydrodynamic model and van der Waals normal form exhibit a behavior similar to the one observed in molecular dynamics simulations.

Comparative outcomes analysis of procedures performed in physician offices and ambulatory surgery centers

HYPOTHESIS

This study compared outcomes to determine whether patient safety is similar in Florida ambulatory surgery centers and offices.

DATA SOURCES

All adverse incident reports to the Florida Board of Medicine for procedure dates April 1, 2000, to April 1, 2002 were reviewed. The numbers of office procedures performed during a 4-month period were used to estimate the total number of procedures. Ambulatory surgery death summaries, adverse incident data, and volumes of procedures for 2000 were procured from the Florida Agency for Health Care Administration.

STUDY SELECTION/DATA EXTRACTION

Adverse incident reports were reviewed by multiple parties; only reports that involved an office surgical procedure and resulted in injury or death were included in the outcomes calculation. Reports were extracted independently by multiple reviewers.

DATA SYNTHESIS

Adverse incidents occurred at a rate of 66 and 5.3 per 100,00 procedures in offices and ambulatory surgery centers, respectively. The death rate per 100,000 procedures performed was 9.2 in offices and 0.78 in ambulatory surgery centers. The relative risks for injuries and deaths for office procedures vs ambulatory surgery centers were 12.4 (95% confidence interval, 9.5-16.2) and 11.8 (95% confidence interval, 5.8-24.1), respectively.

CONCLUSIONS

In this review of surgical procedures performed in offices and ambulatory surgery centers in Florida during a recent 2-year period, there was an approximately 10-fold increased risk of adverse incidents and death in the office setting. If all office procedures had been performed in ambulatory surgery centers, approximately 43 injuries and 6 deaths per year could have been prevented.