Snare or Scalpel: Challenges of Intracardiac Cement Embolism Retrieval.

Intracardiac cement embolism after percutaneous vertebroplasty is a rare, but dangerous, complication, and guiding principles for its management are not well described. The management of this present case of intracardiac cement embolism offers insight to facilitate the treatment decision-making process in symptomatic patients requiring extraction.

Authorized Agent-Controlled Analgesia for Pain Management in Critically Ill Adult Patients.

BACKGROUND: Patient-controlled analgesia is commonly used for adult patients requiring parenteral opioid analgesia in the postoperative setting. However, many patients are unable to use patient-controlled analgesia because of physical or cognitive limitations. Authorized agent-controlled analgesia, in which a nurse or family member activates the patient-controlled analgesia device, has been studied in the pediatric population but has received little attention in adults. OBJECTIVE: To evaluate the efficacy of authorized agent-controlled analgesia in critically ill adult patients. METHODS: A retrospective pilot study was conducted involving 46 patients who were placed on an authorized agent-controlled analgesia protocol in a mixed medical/surgical adult intensive care unit. Critical-Care Pain Observation Tool scores were abstracted for the 24 hours before and after initiation of authorized agent-controlled analgesia. Authorized agent-controlled analgesia was administered by nurses only. RESULTS: The mean (SD) change in pain score was -3.4 (2.0) (95% CI, -4.0 to -2.7), representing a 69% decrease in the mean (SD) pain score from before to after initiation of authorized agent-controlled analgesia (4.8 [1.8] vs 1.5 [1.6]; P < .001). When the results were controlled for time, sedative administration, and opioid medication administration, the effect of authorized agent-controlled analgesia initiation on pain scores remained significant (P < .001). CONCLUSIONS: Use of authorized agent-controlled analgesia is associated with a reduction in pain in critically ill patients. Larger studies are warranted to confirm these findings.

Early results of a modified biological valved conduit for the Bentall procedure.

INTRODUCTION: Few bioprosthetic valved conduits for aortic root surgery are commercially available. Long-term Warfarin therapy (mechanical), potential root calcification (xeno- or homograft valves), and the need for additional ascending aorta grafts are concerns associated with currently used valved conduits. A simplified, self-assembled bioroot conduit comprising currently available materials that facilitates future intervention and exhibits advantages of a bioprosthesis was used. METHODS: From November 2015 to January 2017, 17 consecutive patients underwent urgent or elective aortic root surgery. A bioroot conduit, constructed using 28 or 30 mm of sinus of Valsalva Gelweave tube graft and a 3 to 5 mm smaller bioprosthetic Trifecta valve sewn into the sinus of Valsalva base, was preconstructed in the operating room before sternotomy. The size of the valved conduit was based on the distal ascending aorta or proximal arch and not aortic annular dimension. The bioroot was sutured to the native aortic annulus at the level of the bottom skirt of the Valsalva graft without contacting the sewing cuff of the bioprosthetic valve. RESULTS: All patients survived the operation and were discharged home without long-term anticoagulation therapy. The mean age was 65 ± 12 years, and 13 patients were male. The cardiopulmonary bypass duration was 169 ± 84 minutes, and the cross-clamp (XC) duration was 110 ± 32 minutes. The operation was elective in 12 patients, urgent/emergent in five, and redo in three. CONCLUSION: A simplified self-assembled bioroot Bentall conduit is appropriate for aortic root reconstruction. Use of a patient-tailored valved conduit will not prolong the cardiac ischemic time and will facilitate future valve replacement.

Ketamine in the Prehospital Environment: A National Survey of Paramedics in the United States.

BACKGROUND: Use of ketamine in the prehospital setting may be advantageous due to its potent analgesic and sedative properties and favorable risk profile. Use in the military setting has demonstrated both efficacy and safety for pain relief. The purpose of this study was to assess ketamine training, use, and perceptions in the civilian setting among nationally certified paramedics (NRPs) in the United States. METHODS: A cross-sectional survey of NRPs was performed. The electronic questionnaire assessed paramedic training, authorization, use, and perceptions of ketamine. Included in the analysis were completed surveys of paramedics who held one or more state paramedic credentials, indicated "patient care provider" as their primary role, and worked in non-military settings. Descriptive statistics were calculated. RESULTS: A total of 14,739 responses were obtained (response rate=23%), of which 10,737 (73%) met inclusion criteria and constituted the study cohort. Over one-half (53%) of paramedics reported learning about ketamine during their initial paramedic training. Meanwhile, 42% reported seeking ketamine-related education on their own. Of all respondents, only 33% (3,421/10,737) were authorized by protocol to use ketamine. Most commonly authorized uses included pain management (55%), rapid sequence intubation (RSI; 72%), and chemical restraint/sedation (72%). One-third of authorized providers (1,107/3,350) had never administered ketamine, with another 32% (1,070/3,350) having administered ketamine less than five times in their career. Ketamine was perceived to be safe and effective as the vast majority reported that they were comfortable with the use of ketamine (94%) and would, in similar situations (95%), use it again. CONCLUSION: This was the first large, national survey to assess ketamine training, use, and perceptions among paramedics in the civilian prehospital setting. While training related to ketamine use was commonly reported among paramedics, few were authorized to administer the drug by their agency's protocols. Of those authorized to use ketamine, most paramedics had limited experience administering the drug. Future research is needed to determine why the prevalence of ketamine use is low and to assess the safety and efficacy of ketamine use in the prehospital setting. Buckland DM , Crowe RP , Cash RE , Gondek S , Maluso P , Sirajuddin S , Smith ER , Dangerfield P , Shapiro G , Wanka C , Panchal AR , Sarani B . Ketamine in the prehospital environment: a national survey of paramedics in the United States. Prehosp Disaster Med. 2018;33(1):23-28.

Platelet dysfunction in critically ill patients.

: Thrombelastography Platelet Mapping (TEG-PM) allows for measurement of maximal potential clot strength (MA) and strength from stimulation of arachidonic acid (MA-AA) and adenosine disphosphate (MA-ADP) receptors. This study was conducted to assess degree of platelet dysfunction in critically ill adult patients. A retrospective study of critically ill, adult, nontrauma patients in a medical/surgical ICU was conducted from August 2013 to September 2014. All patients who underwent TEG-PM were enrolled. Patients with intracerebral hemorrhage, following cardiac surgery, or without an APACHE II score were excluded. Patients were divided into those with and without aspirin use. Demographics, APACHE II score, and laboratory results were abstracted. Student t test was used to test significance. A total of 79 patients were enrolled (61% male). Average age and APACHE II score were 61 ±â€Š16 years and 18 ±â€Š9, respectively. Factor-associated coagulation measures and MA were normal in all groups but MA-AA and MA-ADP were significantly reduced irrespective of anticoagulant use. Compared to the nonanticoagulated cohort, MA-AA was significantly reduced in those on aspirin. There was no difference in mortality or length of stay in any cohort. Inhibition of the AA and ADP pathways is common in critically ill patients. Clinical correlation with propensity for bleeding and need for transfusion requires further assessment.

Printable enzyme-embedded materials for methane to methanol conversion.

An industrial process for the selective activation of methane under mild conditions would be highly valuable for controlling emissions to the environment and for utilizing vast new sources of natural gas. The only selective catalysts for methane activation and conversion to methanol under mild conditions are methane monooxygenases (MMOs) found in methanotrophic bacteria; however, these enzymes are not amenable to standard enzyme immobilization approaches. Using particulate methane monooxygenase (pMMO), we create a biocatalytic polymer material that converts methane to methanol. We demonstrate embedding the material within a silicone lattice to create mechanically robust, gas-permeable membranes, and direct printing of micron-scale structures with controlled geometry. Remarkably, the enzymes retain up to 100% activity in the polymer construct. The printed enzyme-embedded polymer motif is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas-liquid reactions.

Inhibition of platelet function is common following even minor injury.

BACKGROUND: Hemorrhage remains the leading cause of preventable death following injury. Whereas significant attention has been paid to the coagulation cascade, there are fewer studies evaluating platelet dysfunction following injury. Thrombelastogram platelet mapping (TEG-PM) allows for the measurement of maximal potential clot strength and clot strength selectively caused by arachidonic acid and adenosine disphosphate receptors on the platelet. The purpose of this study was to determine the incidence and magnitude of receptor-specific platelet dysfunction following injury in patients who are not otherwise pharmacologically anticoagulated. METHODS: A retrospective study of adult trauma patients evaluated at a Level I trauma center from August 2013 to September 2014 was conducted. Platelet function was assessed using TEG-PM. Patients on any anticoagulant or antiplatelet medication were excluded. Patients were divided into those with and without radiographically evident traumatic brain injury (TBI). Demographic variables, Injury Severity Score (ISS), injury pattern, laboratory test results, and mortality were abstracted. Statistical comparisons were made using the Student's t test or Mann-Whitney U-test. RESULTS: The study includes 459 patients, 92% following blunt injury. Median ISS was 5. Patients with TBI (n = 102) were significantly older (median age, 54 years vs. 35 years), were more severely injured (median ISS, 10 vs. 4), had a longer stay and higher mortality (9% vs. 0.3%). Maximal potential clot strength was normal in all cohorts, but the arachidonic acid and adenosine diphosphate pathways were significantly inhibited (30% ± 26% and 58% ± 27%, respectively). There was no correlation between TEG-PM values and ISS, length of stay, or mortality. There was no difference in the TBI cohort. There were no significant differences in TEG-PM parameters in those with an ISS greater than 14. There was no significant change in TEG-PM following platelet transfusion. CONCLUSION: Marked platelet inhibition is common following minor injury. Whereas the clinical significance of this finding remains unknown, the results of this study should be factored in the overall resuscitative strategy. LEVEL OF EVIDENCE: Prognostic/epidemiogic study, level III.

Enzymatic oxidation of methane.

Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, protein-protein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

Effects of zinc on particulate methane monooxygenase activity and structure.

Particulate methane monooxygenase (pMMO) is a membrane-bound metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria. Zinc is a known inhibitor of pMMO, but the details of zinc binding and the mechanism of inhibition are not understood. Metal binding and activity assays on membrane-bound pMMO from Methylococcus capsulatus (Bath) reveal that zinc inhibits pMMO at two sites that are distinct from the copper active site. The 2.6 Å resolution crystal structure of Methylocystis species strain Rockwell pMMO reveals two previously undetected bound lipids, and metal soaking experiments identify likely locations for the two zinc inhibition sites. The first is the crystallographic zinc site in the pmoC subunit, and zinc binding here leads to the ordering of 10 previously unobserved residues. A second zinc site is present on the cytoplasmic side of the pmoC subunit. Parallels between these results and zinc inhibition studies of several respiratory complexes suggest that zinc might inhibit proton transfer in pMMO.