Characterization of a small tRNA-binding protein that interacts with the archaeal proteasome complex.

The proteasome system allows the elimination of functional or structurally impaired proteins. This includes the degradation of nascent peptides. In Archaea, how the proteasome complex interacts with the translational machinery remains to be described. Here, we characterized a small orphan protein, Q9UZY3 (UniProt ID), conserved in Thermococcales. The protein was identified in native pull-down experiments using the proteasome regulatory complex (proteasome-activating nucleotidase [PAN]) as bait. X-ray crystallography and small-angle X-ray scattering experiments revealed that the protein is monomeric and adopts a ß-barrel core structure with an oligonucleotide/oligosaccharide-binding (OB)-fold, typically found in translation elongation factors. Mobility shift experiment showed that Q9UZY3 displays transfer ribonucleic acid (tRNA)-binding properties. Pull-downs, co-immunoprecipitation and isothermal titration calorimetry (ITC) studies revealed that Q9UZY3 interacts in vitro with PAN. Native pull-downs and proteomic analysis using different versions of Q9UZY3 showed that the protein interacts with the assembled PAN-20S proteasome machinery in Pyrococcus abyssi (Pa) cellular extracts. The protein was therefore named Pbp11, for Proteasome-Binding Protein of 11 kDa. Interestingly, the interaction network of Pbp11 also includes ribosomal proteins, tRNA-processing enzymes and exosome subunits dependent on Pbp11's N-terminal domain that was found to be essential for tRNA binding. Together these data suggest that Pbp11 participates in an interface between the proteasome and the translational machinery.

Analysis of the inhibiting activity of reversion-inducing cysteine-rich protein with Kazal motifs (RECK) on matrix metalloproteinases.

Matrix metalloproteinases (MMPs) occur in 23 human paralogues with key functions in physiology, and their activity is controlled by protein inhibitors. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), which is essential for embryogenesis and tumour suppression, has been reported to inhibit MMPs. Here, we developed eukaryotic and bacterial expression systems for different RECK variants and analysed their inhibitory capacity against representative MMPs in vitro. We could not detect any significant inhibition. Instead, we found that partially purified RECK from the conditioned medium of transfected Expi293F cells but not that of ExpiCHO-S or Drosophila Schneider cells contained a contaminant with proteolytic activity. The contaminant was removed through treatment with a small-molecule serine peptidase inhibitor and additional chromatographic purification. A tantamount contaminant was further detected in an equivalent expression system of the N-terminal fragment of the proteoglycan testican 3, but not in those of two other proteins. These results indicate that previous reports of inhibitory activity of recombinant RECK on MMPs, which were performed with partially purified samples, were probably masked by a coeluting contaminant present in the supernatant of HEK293-derived cells. Thus, RECK is probably not a direct inhibitor of MMP catalytic activity but may still regulate MMPs through other mechanisms.

Relationship between skin and urine colonization and surgical site infection in the proximal femur fracture: a prospective study.

PURPOSE: Antibiotic prophylaxis is routinely used in the surgical management of proximal femur fractures. The role of bacterial colonization of the skin and urine in the development of deep surgical site infections (SSI) is yet to be elucidated. This study aimed to evaluate the role of previous skin and urine colonization in the development of deep SSI after a proximal femoral fracture surgery. METHODS: We conducted a prospective observational study in 326 patients > 64 years old, who were scheduled to surgery. Cultures from skin samples of the surgical site and from urine were performed prior to the procedure, and cefazoline was administered as prophylaxis. RESULTS: Skin microbiota was isolated in 233 (71.5%) cases; 8 (2.5%) samples were positive for other bacteria, and 85 (26%) were negative. Of 236 urine samples, 168 were negative or contaminated (71.2%), and 68 (28.8%) were positive, being 58/236 for Enterobacterales (24.6%). Acute deep SSI were diagnosed in nine out of 326 patients (2.7%), and two (22%) were infected by Gram-negative bacilli. Of the 9 cases, normal skin microbiota was isolated in 7 (78%), and the remaining two were negative. Seven cases had negative or contaminated urine cultures, and the one with E. coli did not correlate with SSI bacteria. CONCLUSION: In our elderly hip fracture population, most patients harbored normal skin microbiota, and Enterobacterales urine cultures were positive in one-quarter of cases. There was no relationship between skin colonization, urine culture, and deep SSI. We therefore do not believe that our patients would benefit from modifying the current antibiotic prophylaxis.

Recombinant production, purification, crystallization, and structure analysis of human transforming growth factor ß2 in a new conformation.

Transforming growth factor ß is a disulfide-linked dimeric cytokine that occurs in three highly related isoforms (TGFß1-TGFß3) engaged in signaling functions through binding of cognate TGFß receptors. To regulate this pathway, the cytokines are biosynthesized as inactive pro-TGFßs with an N-terminal latency-associated protein preceding the mature moieties. Due to their pleiotropic implications in physiology and pathology, TGFßs are privileged objects of in vitro studies. However, such studies have long been limited by the lack of efficient human recombinant expression systems of native, glycosylated, and homogenous proteins. Here, we developed pro-TGFß2 production systems based on human Expi293F cells, which yielded >2 mg of pure histidine- or Strep-tagged protein per liter of cell culture. We assayed this material biophysically and in crystallization assays and obtained a different crystal form of mature TGFß2, which adopted a conformation deviating from previous structures, with a distinct dimeric conformation that would require significant rearrangement for binding of TGFß receptors. This new conformation may be reversibly adopted by a certain fraction of the mature TGß2 population and represent a hitherto undescribed additional level of activity regulation of the mature growth factor once the latency-associated protein has been separated.

Recombinant production of human α2-macroglobulin variants and interaction studies with recombinant G-related α2-macroglobulin binding protein and latent transforming growth factor-ß2.

α2-Macroglobulins (α2Ms) regulate peptidases, hormones and cytokines. Mediated by peptidase cleavage, they transit between native, intact forms and activated, induced forms. α2Ms have been studied over decades using authentic material from primary sources, which was limited by sample heterogeneity and contaminants. Here, we developed high-yield expression systems based on transient transfection in Drosophila Schneider 2 and human Expi293F cells, which produced pure human α2M (hα2M) at ~1.0 and ~0.4 mg per liter of cell culture, respectively. In both cases, hα2M was mainly found in the induced form. Shorter hα2M variants encompassing N-/C-terminal parts were also expressed and yielded pure material at ~1.6/~1.3 and ~3.2/~4.6 mg per liter of insect or mammalian cell culture, respectively. We then analyzed the binding of recombinant and authentic hα2M to recombinant latent human transforming growth factor-ß2 (pro-TGF-ß2) and bacterial G-related α2M binding protein (GRAB) by surface plasmon resonance, multiple-angle laser light scattering, size-exclusion chromatography, fluorogenic labelling, gel electrophoresis and Western-blot analysis. Two GRAB molecules formed stable complexes of high affinity with native and induced authentic hα2M tetramers. The shorter recombinant hα2M variants interacted after preincubation only. In contrast, pro-TGF-ß2 did not interact, probably owing to hindrance by the N-terminal latency-associated protein of the cytokine.

Epidural Space Identification With Loss of Resistance Technique for Epidural Analgesia During Labor: A Randomized Controlled Study Using Air or Saline-New Arguments for an Old Controversy.

BACKGROUND: The best technique to identify the epidural space for labor analgesia is still unclear despite the publication of various randomized controlled studies and meta-analyses. Our aim was to assess the superiority of the saline loss of resistance (SLOR) technique over the air loss of resistance (ALOR) technique with respect to the quality of the block. METHODS: Consenting parturients admitted to our obstetric suite for spontaneous or induced labor were randomized to receive epidural analgesia using either the ALOR or SLOR technique. Our primary outcome was to compare the impact of the SLOR and ALOR technique on pain score improvement measured 30 minutes after administration of epidural block. Our secondary outcomes included the density of motor blockade and analgesic efficacy measured at 30 minutes. Primary and secondary outcomes were compared using the Student t test and Mann-Whitney U test. Statistical significance was set at P < .017 for primary and secondary outcomes, considering Bonferroni correction for multiple comparisons. Other comparisons were considered exploratory. RESULTS: Four hundred parturients were included; 24 were excluded from the final analysis. After 30 minutes, pain score reduction (ALOR, 4.7 ± 2.9/10; SLOR, 4.9 ± 3.0/10; P = .49), motor block (ALOR, 1.4 ± 0.8; SLOR, 1.3 ± 0.8; P = .27), and efficacy of the block (ALOR, 1.0 ± 0.7; SLOR, 1.0 ± 0.6; P = .87) did not differ significantly between groups. CONCLUSIONS: Pain score reduction after 30 minutes and onset of the block were not affected by the technique used to locate the epidural space.

Matrix metalloproteinases outside vertebrates.

The matrix metalloproteinase (MMP) family belongs to the metzincin clan of zinc-dependent metallopeptidases. Due to their enormous implications in physiology and disease, MMPs have mainly been studied in vertebrates. They are engaged in extracellular protein processing and degradation, and present extensive paralogy, with 23 forms in humans. One characteristic of MMPs is a ~165-residue catalytic domain (CD), which has been structurally studied for 14 MMPs from human, mouse, rat, pig and the oral-microbiome bacterium Tannerella forsythia. These studies revealed close overall coincidence and characteristic structural features, which distinguish MMPs from other metzincins and give rise to a sequence pattern for their identification. Here, we reviewed the literature available on MMPs outside vertebrates and performed database searches for potential MMP CDs in invertebrates, plants, fungi, viruses, protists, archaea and bacteria. These and previous results revealed that MMPs are widely present in several copies in Eumetazoa and higher plants (Tracheophyta), but have just token presence in eukaryotic algae. A few dozen sequences were found in Ascomycota (within fungi) and in double-stranded DNA viruses infecting invertebrates (within viruses). In contrast, a few hundred sequences were found in archaea and >1000 in bacteria, with several copies for some species. Most of the archaeal and bacterial phyla containing potential MMPs are present in human oral and gut microbiomes. Overall, MMP-like sequences are present across all kingdoms of life, but their asymmetric distribution contradicts the vertical descent model from a eubacterial or archaeal ancestor. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

Structural and functional insight into pan-endopeptidase inhibition by α2-macroglobulins.

Peptidases must be exquisitely regulated to prevent erroneous cleavage and one control is provided by protein inhibitors. These are usually specific for particular peptidases or families and sterically block the active-site cleft of target enzymes using lock-and-key mechanisms. In contrast, members of the +1400-residue multi-domain α2-macroglobulin inhibitor family (α2Ms) are directed against a broad spectrum of endopeptidases of disparate specificities and catalytic types, and they inhibit their targets without disturbing their active sites. This is achieved by irreversible trap mechanisms resulting from large conformational rearrangement upon cleavage in a promiscuous bait region through the prey endopeptidase. After decades of research, high-resolution structural details of these mechanisms have begun to emerge for tetrameric and monomeric α2Ms, which use 'Venus-flytrap' and 'snap-trap' mechanisms, respectively. In the former, represented by archetypal human α2M, inhibition is exerted through physical entrapment in a large cage, in which preys are still active against small substrates and inhibitors that can enter the cage through several apertures. In the latter, represented by a bacterial α2M from Escherichia coli, covalent linkage and steric hindrance of the prey inhibit activity, but only against very large substrates.

Pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus ® ) for the perioperative management of a caesarean section in a patient with severe cardiomyopathy / Análise do contorno do pulso calibrado por termodiluição transpulmonar (Picco Plus ® ) para o manejo perioperatório de cesariana em paciente com miocardiopatia grave

ABSTRACT BACKGROUND: The delivery of cardiac patients is a challenge for the anaesthesiologist, to whom the welfare of both the mother and the foetus is a main issue. In case of caesarean section, advanced monitoring allows to optimize haemodynamic condition and to improve morbidity and mortality. OBJECTIVE: To describe the use of pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus® for the perioperative management of a caesarean section in a patient with severe cardiomyopathy. CASE REPORT: We describe the case of a 28-year-old woman with a congenital heart disease who was submitted to a caesarean section under general anaesthesia for maternal pathology and foetal breech presentation. Intra- and post-operative management was optimized by advanced haemodynamic monitorization obtained by pulse contour wave analysis and thermodilution calibration (Picco Plus® monitor). The information about preload, myocardial contractility and postcharge was useful in guiding the fluid therapy and the use of vasoactive drugs. CONCLUSION: This case report illustrates the importance of advanced haemodynamic monitoring with an acceptably invasive device in obstetric patients with high cardiac risk. The increasing experience in advanced haemodynamic management will probably permit to decrease morbidity and mortality of obstetric patients in the future.

RESUMO JUSTIFICATIVA: O parto em pacientes cardíacas é um desafio para o anestesiologista, para o qual o bem-estar tanto da mãe quanto do feto é a questão principal. Em caso de cesariana, o monitoramento avançado permite melhorar a condição hemodinâmica e diminuir a morbidade e mortalidade. OBJETIVO: Descrever o uso da análise do contorno do pulso calibrado por termodiluição transpulmonar (Picco Plus®) para o manejo perioperatório de cesariana em paciente com miocardiopatia grave. RELATO DE CASO: Descrevemos o caso de uma paciente de 28 anos com uma doença cardíaca congênita, submetida a uma cesariana sob anestesia geral devido a afecção materna e apresentação fetal pélvica. O manejo nos períodos intraoperatório e pós-operatório foi aprimorado por monitoração hemodinâmica avançada obtida pela análise do contorno da onda de pulso e calibração por termodiluição (monitor Picco Plus®). As informações sobre pré-carga, pós-carga e contratilidade miocárdica foram úteis para orientar a reposição hídrica e o uso de medicamentos vasoativos. CONCLUSÃO: Este relato de caso ilustra a importância da monitoração hemodinâmica avançada com dispositivo aceitavelmente invasivo em pacientes obstétricas com alto risco cardíaco. O aumento do conhecimento no manejo hemodinâmico avançado provavelmente possibilitará a redução da morbidade e mortalidade de pacientes obstétricas no futuro.

Reperfusion injury protection during Basic Life Support improves circulation and survival outcomes in a porcine model of prolonged cardiac arrest.

OBJECTIVE: Ischemic postconditioning (PC) using three intentional pauses at the start of cardiopulmonary resuscitation (CPR) improves outcomes after cardiac arrest in pigs when epinephrine (epi) is used before defibrillation. We hypothesized PC, performed during basic life support (BLS) in the absence of epinephrine, would reduce reperfusion injury and enhance 24h functional recovery. DESIGN: Prospective animal investigation. SETTING: Animal laboratory SUBJECTS: Female farm pigs (n=46, 39±1kg). INTERVENTIONS: Protocol A: After 12min of ventricular fibrillation (VF), 28 pigs were randomized to four groups: (A) Standard CPR (SCPR), (B) active compression-decompression CPR with an impedance threshold device (ACD-ITD), (C) SCPR+PC (SCPR+PC) and (D) ACD-ITD CPR+PC. Protocol B: After 15min of VF, 18 pigs were randomized to ACD-ITD CPR or ACD-ITD+PC. The BLS duration was 2.75min in Protocol A and 5min in Protocol B. Following BLS, up to three shocks were delivered. Without return of spontaneous circulation (ROSC), CPR was resumed and epi (0.5mg) and defibrillation delivered. The primary end point was survival without major adverse events. Hemodynamic parameters and left ventricular ejection fraction (LVEF) were also measured. Data are presented as mean±SEM. MEASUREMENTS AND MAIN RESULTS: Protocol A: ACD-ITD+PC (group D) improved coronary perfusion pressure after 3min of BLS versus the three other groups (28±6, 35±7, 23±5 and 47±7 for groups A, B, C, D respectively, p=0.05). There were no significant differences in 24h survival between groups. PROTOCOL B: LVEF 4h post ROSC was significantly higher with ACD-ITD+PC vs ACD-ITD alone (52.5±3% vs. 37.5±6.6%, p=0.045). Survival rates were significantly higher with ACD-ITD+PC vs. ACD-ITD alone (p=0.027). CONCLUSIONS: BLS using ACD-ITD+PC reduced post resuscitation cardiac dysfunction and improved functional recovery after prolonged untreated VF in pigs. PROTOCOL NUMBER: 12-11.

Pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus(®)) for the perioperative management of a caesarean section in a patient with severe cardiomyopathy.

BACKGROUND: The delivery of cardiac patients is a challenge for the anaesthesiologist, to whom the welfare of both the mother and the foetus is a main issue. In case of caesarean section, advanced monitoring allows to optimize haemodynamic condition and to improve morbidity and mortality. OBJECTIVE: To describe the use of pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus(®)) for the perioperative management of a caesarean section in a patient with severe cardiomyopathy. CASE REPORT: We describe the case of a 28-year-old woman with a congenital heart disease who was submitted to a caesarean section under general anaesthesia for maternal pathology and foetal breech presentation. Intra- and post-operative management was optimized by advanced haemodynamic monitorization obtained by pulse contour wave analysis and thermodilution calibration (Picco Plus(®) monitor). The information about preload, myocardial contractility and postcharge was useful in guiding the fluid therapy and the use of vasoactive drugs. CONCLUSION: This case report illustrates the importance of advanced haemodynamic monitoring with an acceptably invasive device in obstetric patients with high cardiac risk. The increasing experience in advanced haemodynamic management will probably permit to decrease morbidity and mortality of obstetric patients in the future.

[Pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus(®)) for the perioperative management of a caesarean section in a patient with severe cardiomyopathy]. / Análise do contorno do pulso calibrado por termodiluição transpulmonar (Picco Plus(®)) para o manejo perioperatório de cesariana em paciente com miocardiopatia grave.

BACKGROUND: The delivery of cardiac patients is a challenge for the anaesthesiologist, to whom the welfare of both the mother and the foetus is a main issue. In case of caesarean section, advanced monitoring allows to optimize haemodynamic condition and to improve morbidity and mortality. OBJECTIVE: To describe the use of pulse contour analysis calibrated by Trans-pulmonar thermodilution (Picco Plus(®)) for the perioperative management of a caesarean section in a patient with severe cardiomyopathy. CASE REPORT: We describe the case of a 28-year-old woman with a congenital heart disease who was submitted to a caesarean section under general anaesthesia for maternal pathology and foetal breech presentation. Intra- and post-operative management was optimized by advanced haemodynamic monitorization obtained by pulse contour wave analysis and thermodilution calibration (Picco Plus(®) monitor). The information about preload, myocardial contractility and postcharge was useful in guiding the fluid therapy and the use of vasoactive drugs. CONCLUSION: This case report illustrates the importance of advanced haemodynamic monitoring with an acceptably invasive device in obstetric patients with high cardiac risk. The increasing experience in advanced haemodynamic management will probably permit to decrease morbidity and mortality of obstetric patients in the future.

Effect of regulating airway pressure on intrathoracic pressure and vital organ perfusion pressure during cardiopulmonary resuscitation: a non-randomized interventional cross-over study.

BACKGROUND: The objective of this investigation was to evaluate changes in intrathoracic pressure (Ppl), airway pressure (Paw) and vital organ perfusion pressures during standard and intrathoracic pressure regulation (IPR)-assisted cardiopulmonary resuscitation (CPR). METHODS: Multiple CPR interventions were assessed, including newer ones based upon IPR, a therapy that enhances negative intrathoracic pressure after each positive pressure breath. Eight anesthetized pigs underwent 4 min of untreated ventricular fibrillation followed by 2 min each of sequential interventions: (1) conventional standard CPR (STD), (2) automated active compression decompression (ACD) CPR, (3) ACD+ an impedance threshold device (ITD) CPR or (4) ACD+ an intrathoracic pressure regulator (ITPR) CPR, the latter two representing IPR-based CPR therapies. Intrapleural (Ppl), airway (Paw), right atrial, intracranial, and aortic pressures, along with carotid blood flow and end tidal CO2, were measured and compared during each CPR intervention. RESULTS: The lowest mean and decompression phase Ppl were observed with IPR-based therapies [Ppl mean (mean ± SE): STD (0.8 ± 1.1 mmHg); ACD (-1.6 ± 1.6); ACD-ITD (-3.7 ± 1.5, p < 0.05 vs. both STD and ACD); ACD-ITPR (-7.0 ± 1.9, p < 0.05 vs. both STD and ACD)] [Ppl decompression (mean ± SE): STD (-6.3 ± 2.2); ACD (-13.0 ± 3.8); ACD-ITD -16.9 ± 3.6, p < 0.05 vs. both STD and ACD); ACD-ITPR -18.7 ± 3.5, p < 0.05 vs. both STD and ACD)]. Interventions with the lower mean or decompression phase Ppl also demonstrated lower Paw and were associated with higher vital organ perfusion pressures. CONCLUSIONS: IPR-based CPR methods, specifically ACD-ITPR, yielded the most pronounced reduction in both Ppl and Paw and resulted in the most favorable augmentation of hemodynamics during CPR.

Intrathoracic pressure regulation to treat intraoperative hypotension: A phase II pilot study.

BACKGROUND: Intraoperative hypotension secondary to acute blood loss and fluid shifts increases morbidity and mortality. Intrathoracic pressure regulation (IPR) is a new therapy that enhances circulation by increasing venous return with a negative intrathoracic pressure created noninvasively, either actively (vacuum source or patient inspiration) or passively (chest recoil during cardiopulmonary resuscitation). OBJECTIVE: In this Phase II pilot study, we tested the hypothesis that active IPR therapy would improve the haemodynamic status of patients who developed clinically significant hypotension during abdominal surgery. DESIGN: A phase II, single cohort, interventional pilot study. SETTING: University of Minnesota Fairview Hospital. PATIENTS: Twenty-two patients [American Society of Anesthesiologists (ASA) physical status I to III] were enrolled prospectively of whom 15 experienced intraoperative hypotension. INTERVENTION: If intraoperative hypotension occurred more than 10 min after induction, the IPR device was applied immediately for a minimum of 10 min. MAIN OUTCOME MEASURE: The hypotensive SBP immediately before the start of IPR treatment was compared with the SBP obtained at the end of IPR therapy. The paired Student's t-test was used to determine statistical significance (P < 0.05). RESULTS: Fifteen of the 22 patients enrolled experienced 18 hypotensive episodes, which were treated with at least 10 min of IPR therapy. Fourteen episodes responded to IPR alone and four episodes (four patients) required additional fluid and vasopressor therapy to treat the hypotension. The group mean ± SD SBPs at the onset of the IPR treatment and at the end of IPR treatment were 90.7 ± 9.7 and 98.4 ± 17.4 mmHg (P = 0.02), respectively. The maximum SBP reached during the treatment was 105.6 ± 19.6 mmHg. Pulse pressure increased from 36.8 ± 8.5 mmHg immediately before IPR treatment to 41.5 ± 11.1 mmHg (P = 0.02) at the end of IPR treatment. Mean arterial pressure (MAP) increased from 66.3 ± 9.4 mmHg immediately before IPR treatment to 71.5 ± 14.4 mmHg (P = 0.03) at the end of IPR treatment. No adverse events were identified with use of the IPR device. CONCLUSION: IPR may be useful in treating intraoperative hypotension without additional fluid or vasopressor therapy. No significant adverse events were observed. On the basis of this phase II pilot study, a larger study is justified.

Enhanced perfusion during advanced life support improves survival with favorable neurologic function in a porcine model of refractory cardiac arrest.

OBJECTIVE: To improve the likelihood for survival with favorable neurologic function after cardiac arrest, we assessed a new advanced life support approach using active compression-decompression cardiopulmonary resuscitation plus an intrathoracic pressure regulator. DESIGN: Prospective animal investigation. SETTING: Animal laboratory. SUBJECTS: Female farm pigs (n = 25) (39 ± 3 kg). INTERVENTIONS: Protocol A: After 12 minutes of untreated ventricular fibrillation, 18 pigs were randomized to group A-3 minutes of basic life support with standard cardiopulmonary resuscitation, defibrillation, and if needed 2 minutes of advanced life support with standard cardiopulmonary resuscitation; group B-3 minutes of basic life support with standard cardiopulmonary resuscitation, defibrillation, and if needed 2 minutes of advanced life support with active compression-decompression plus intrathoracic pressure regulator; and group C-3 minutes of basic life support with active compression-decompression cardiopulmonary resuscitation plus an impedance threshold device, defibrillation, and if needed 2 minutes of advanced life support with active compression-decompression plus intrathoracic pressure regulator. Advanced life support always included IV epinephrine (0.05 µg/kg). The primary endpoint was the 24-hour Cerebral Performance Category score. Protocol B: Myocardial and cerebral blood flow were measured in seven pigs before ventricular fibrillation and then following 6 minutes of untreated ventricular fibrillation during sequential 5 minutes treatments with active compression-decompression plus impedance threshold device, active compression-decompression plus intrathoracic pressure regulator, and active compression-decompression plus intrathoracic pressure regulator plus epinephrine. MEASUREMENTS AND MAIN RESULTS: Protocol A: One of six pigs survived for 24 hours in group A versus six of six in groups B and C (p = 0.002) and Cerebral Performance Category scores were 4.7 ± 0.8, 1.7 ± 0.8, and 1.0 ± 0, respectively (p = 0.001). Protocol B: Brain blood flow was significantly higher with active compression-decompression plus intrathoracic pressure regulator compared with active compression-decompression plus impedance threshold device (0.39 ± 0.23 vs 0.27 ± 0.14 mL/min/g; p = 0.03), whereas differences in myocardial perfusion were not statistically significant (0.65 ± 0.81 vs 0.42 ± 0.36 mL/min/g; p = 0.23). Brain and myocardial blood flow with active compression-decompression plus intrathoracic pressure regulator plus epinephrine were significantly increased versus active compression-decompression plus impedance threshold device (0.40 ± 0.22 and 0.84 ± 0.60 mL/min/g; p = 0.02 for both). CONCLUSION: Advanced life support with active compression-decompression plus intrathoracic pressure regulator significantly improved cerebral perfusion and 24-hour survival with favorable neurologic function. These findings support further evaluation of this new advanced life support methodology in humans.

Awakening after cardiac arrest and post resuscitation hypothermia: are we pulling the plug too early?

BACKGROUND: Time to awakening after out-of-hospital cardiac arrest (OHCA) and post-resuscitation therapeutic hypothermia (TH) varies widely. We examined the time interval from when comatose OHCA patients were rewarmed to 37°C to when they showed definitive signs of neurological recovery and tried to identify potential predictors of awakening. METHODS: With IRB approval, a retrospective case study was performed in OHCA patients who were comatose upon presentation to a community hospital during 2006-2010. They were treated with TH (target of 33°C) for 24h, rewarmed, and discharged alive. Comatose patients were generally treated medically after TH for at least 48h before any decision to withdraw supportive care was made. Pre-hospital TH was not used. Data are expressed as medians and interquartile range. RESULTS: The 89 patients treated with TH in this analysis were divided into three groups based upon the time between rewarming to 37°C and regaining consciousness. The 69 patients that regained consciousness in ≤48h after rewarming were termed "early-awakeners". Ten patients regained consciousness 48-72h after rewarming and were termed "intermediate-awakeners". Ten patients remained comatose and apneic >72h after rewarming but eventually regained consciousness; they were termed "late-awakeners". The ages for the early, intermediate and late awakeners were 56 [49,65], 62 [48,74], and 58 [55,65] years, respectively. Nearly 67% were male. Following rewarming, the time required to regain consciousness for the early, intermediate and late awakeners was 9 [2,18] (range 0-47), 60.5 [56,64.5] (range 49-71), and 126 [104,151]h (range 73-259), respectively. Within 90 days of hospital admission, favorable neurological function based on a Cerebral Performance Category (CPC) score of 1 or 2 was reported in 67/69 early, 10/10 intermediate, and 8/10 late awakeners. CONCLUSION: Following OHCA and TH, arbitrary withdrawal of life support <48h after rewarming may prematurely terminate life in many patients with the potential for full neurological recovery. Additional clinical markers that correlate with late awakening are needed to better determine when withdrawal of support is appropriate in OHCA patients who remain comatose >48h after rewarming.