Balloons on the battlefield: REBOA implementation in the UK Defence Medical Services

Established in 2018, the Defence Endovascular Resuscitation (DefER) group recognised that resuscitative endovascular balloon occlusion of the aorta (REBOA) offered an option to improve survival in battle casualties dying from haemorrhage, particularly in remote and austere surgical settings. Following a successful jHub opportunity assessment, DefER purchased training and operational kit at pace. By 1 April 2019, the first forward surgical group undertook a bespoke endovascular training and assessment package. Results of the pilot were presented back to a jHub 4* Innovation Board, which initially awarded £500 000 to fund the project to full implementation. Med Op Cap provided a solution to establish REBOA as a core capability on to the 370 modules. REBOA catheters and arterial access kit are now available to deployed Role 2 facilities across defence as an adjunct to damage control resuscitation in specific circumstances. REBOA has, from a standing start, gained pan-Defence Medical Services (DMS) endorsement and has been integrated into deployed damage control resuscitation. To establish a new resuscitation capability across all Role 2 platforms within 15 months of inception represents implementation at pace. This agility was unlocked by empowering clinicians to develop the platform in conjunction with commercial procurement. This article describes how this innovative pathway facilitated the rapid introduction of a lifesaving haemorrhage control technique to equip DMS clinicians.

The effect of intestinal microbiota dysbiosis on growth and detection of carbapenemase-producing Enterobacterales within an in vitro gut model

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) can colonize the gut and are of major clinical concern. Identification of CPE colonization is problematic; there is no gold-standard detection method, and the effects of antibiotic exposure and microbiota dysbiosis on detection are unknown.

AIM

Based on a national survey we selected four CPE screening assays in common use. We used a clinically reflective in vitro model of human gut microbiota to investigate the performance of each test to detect three different CPE strains under different, clinically relevant antibiotic exposures.

METHODS

Twelve gut models were seeded with a pooled faecal slurry and exposed to CPE either before, after, concomitant with, or in the absence of piperacillin-tazobactam (358 mg/L, 3 × daily, seven days). Total Enterobacterales and CPE populations were enumerated daily. Regular screening for CPE was performed using Cepheid Xpert® Carba-R molecular test, and with Brilliance™ CRE, Colorex™ mSuperCARBA and CHROMID® CARBA SMART agars.

FINDINGS

Detection of CPE when the microbiota are intact is problematic. Antibiotic exposure disrupts microbiota populations and allows CPE proliferation, increasing detection. The performances of assays varied, particularly with respect to different CPE strains. The Cepheid assay performed better than the three agar methods for detecting a low level of CPE within an intact microbiota, although performance of all screening methods was comparable when CPE populations increased in a disrupted microbiota.

CONCLUSION

CPE strains differed in their dynamics of colonization in an in vitro gut model and in their subsequent response to antibiotic exposure. This affected detection by molecular and screening methods, which has implications for the sensitivity of CPE screening in healthcare settings.

Intravascular ultrasound, performed during resuscitative endovascular balloon occlusion of the aorta (REBOA), confirms correct balloon deployment and haemostasis - a potential solution for remote, austere and military settings

Introduction

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is rapidly evolving as an emergency haemorrhage control technique. It has wide potential applicability in remote and austere settings, and following military trauma where prolonged field care might be required. However, rapid confirmation of balloon delivery is a challenge which relies on estimates derived from anatomical measurements or trans-abdominal ultrasound. In addition, confirmation of adequate balloon expansion is difficult. Intravascular ultrasound (IVUS) offers a solution to these two issues, making REBOA a deliverable therapy in the pre-hospital and early hospital settings.

Methods

In an animal model of severe ballistic trauma, following characterisation of the technique, an IVUS-REBOA device was configured, combining a peripheral angioplasty balloon and a digital coronary IVUS catheter. This was introduced via a sheath into the femoral vessel over a conventional angioplasty guide wire.

Results

Real time IVUS imaging allowed confirmation of delivery of the balloon to the aorta, and also demonstrated full apposition once deployed. Furthermore, using ChromaFlo imaging, the device confirmed loss of pulsatile flow in the aorta after deployment, correlating with loss of transduced femoral pressure traces. Post-mortem examination confirmed correct anatomical balloon placement.

Summary

For the first time, in a porcine pilot study, we have demonstrated that IVUS-REBOA is feasible and confirms both correct balloon placement and haemostasis. It has potential to offer advantages to REBOA operators especially during the pre-hospital and retrieval phases, and in the early phase of hospital delivered damage control resuscitation at remote locations.

REBOA at Role 2 Afloat: resuscitative endovascular balloon occlusion of the aorta as a bridge to damage control surgery in the military maritime setting

Role 2 Afloat provides a damage control resuscitation and surgery facility in support of maritime, littoral and aviation operations. Resuscitative endovascular balloon occlusion of the aorta (REBOA) offers a rapid, effective solution to exsanguinating haemorrhage from pelvic and non-compressible torso haemorrhage. It should be considered when the patient presents in a peri-arrest state, if surgery is likely to be delayed, or where the single operating table is occupied by another case. This paper will outline the data in support of endovascular haemorrhage control, describe the technique and explore how REBOA could be delivered using equipment currently available in the Royal Navy Role 2 Afloat equipment module. Also discussed are potential future directions in endovascular resuscitation.

The Crystal Structure of Potassium Nickel Arsenate; KNiAsO4

The crystal structure of potassium nickel arsenate. KNiAsO4 has been determined by high resolution powder neutron diffraction at 30 K. The unit cell of KNiAsO4 is rhombohedral. space group R3̄, with hexagonal cell constants, a = 4.97208(2) (Å). c = 28.52606(10) (Å). The compound is isomorphous with NaNiAsO4.

Nitrogen Fixation and Carbon Dioxide Assimilation in Rhizobium japonicum

In free-living Rhizobium japonicum cultures, the stimulatory effect of CO(2) on nitrogenase (acetylene reduction) activity was mediated through ribulose bisphosphate carboxylase activity. Two mutant strains (CJ5 and CJ6) of R. japonicum defective in CO(2) fixation were isolated by mitomycin C treatment. No ribulose bisphosphate carboxylase activity could be detected in strain CJ6, but a low level of enzyme activity was present in strain CJ5. Mutant strain CJ5 also exhibited pleiotropic effects on carbon metabolism. The mutant strains possessed reduced levels of hydrogen uptake, formate dehydrogenase, and phosphoribulokinase activities, which indicated a regulatory relationship between these enzymes. The CO(2)-dependent stimulation of nitrogenase activity was not observed in the mutant strains. Both mutant strains nodulated soybean plants and fixed nitrogen at rates comparable to that of the wild-type strain.

Long-term mortality after first psychiatric admission

BACKGROUND

Little is known about the long-term mortality and causes of death after first psychiatric admission.

METHOD

A consecutive series of 87 patients admitted for the first time from a strictly defined catchment area to Saxondale Hospital, Nottinghamshire, who were discharged in 1974 and 1975, were traced in 1992 to either their general practitioner or death. The causes of their deaths were ascertained and the observed mortality was compared with expected mortality.

RESULTS

Twelve subjects had died. None had committed suicide, and there were no open verdicts or accidental deaths. Although the observed mortality was higher than expected, there was no significant excess.

CONCLUSIONS

There may be little scope for reducing suicide rates by targeting patients for careful follow-up after discharge from their first psychiatric admission. More research is required before large investments are made in potentially fruitless interventions to achieve the objectives of The Health of the Nation.

Identification of essential nucleotides in an upstream repressing sequence of Saccharomyces cerevisiae by selection for increased expression of TRK2

The TRK2 gene in Saccharomyces cerevisiae encodes a membrane protein involved in potassium transport and is expressed at extremely low levels. Dominant cis-acting mutations (TRK2D), selected by their ability to confer TRK2-dependent growth on low-potassium medium, identified an upstream repressor element (URS1-TRK2) in the TRK2 promoter. The URS1-TRK2 sequence (5'-AGCCGCACG-3') shares six nucleotides with the ubiquitous URS1 element (5'-AGCCGCCGA-3'), and the protein species binding URS1-CAR1 (URSF) is capable of binding URS1-TRK2 in vitro. Sequence analysis of 17 independent repression-defective TRK2D mutations identified three adjacent nucleotides essential for URS1-mediated repression in vivo. Our results suggest a role for context effects with regard to URS1-related sequences: several mutant alleles of the URS1 element previously reported to have little or no effect when analyzed within the context of a heterologous promoter (CYC1) [Luche, R.M., Sumrada, R. & Cooper, T.G. (1990) Mol. Cell. Biol. 10, 3884-3895] have major effects on repression in the context of their native promoters (TRK2 and CAR1). TRK2D mutations that abolish repression also reveal upstream activating sequence activity either within or adjacent to URS1. Additivity between TRK2D and sin3 delta mutations suggest that SIN3-mediated repression is independent of that mediated by URS1.

Genetic and molecular analysis of DNA43 and DNA52: two new cell-cycle genes in Saccharomyces cerevisiae

Two Saccharomyces cerevisiae genes previously unknown to be required for DNA synthesis have been identified by screening a collection of temperature-sensitive mutants. The effects of mutations in DNA43 and DNA52 on the rate of S phase DNA synthesis were detected by monitoring DNA synthesis in synchronous populations that were obtained by isopycnic density centrifugation. dna43-1 and dna52-1 cells undergo cell-cycle arrest at the restrictive temperature (37 degrees C), exhibiting a large-budded terminal phenotype; the nuclei of arrested cells are located at the neck of the bud and have failed to undergo DNA replication. These phenotypes suggest that DNA43 and DNA52 are required for entry into or completion of S phase. DNA43 and DNA52 were cloned by their abilities to suppress the temperature-sensitive lethal phenotypes of dna43-1 and dna52-1 cells, respectively. DNA sequence analysis suggested that DNA43 and DNA52 encode proteins of 59.6 and 80.6 kDa, respectively. Both DNA43 and DNA52 are essential for viability and genetic mapping experiments indicate that they represent previously unidentified genes: DNA43 is located on chromosome IX, 32 cM distal from his5 and DNA52 is located on chromosome IV, 0.9 cM from cdc34.

TRK2 is required for low affinity K+ transport in Saccharomyces cerevisiae

TRK1, the gene encoding the high affinity K+ transporter in Saccharomyces cerevisiae, is nonessential due to the existence of a functionally independent low affinity transporter. To identify the gene(s) encoding the low affinity K+ transporter, we screened trk1 delta cells for mutants (Kla-) that require higher concentrations of K+ in the medium to support growth. trk1 delta trk2 mutants require up to tenfold higher concentrations of K+ to exhibit normal growth compared to trk1 delta TRK2 cells. K+ and 86Rb+ transport assays demonstrate that the mutant phenotype is due to defective K+ transport (uptake). Each of 38 independent mutants contains a mutation in the same gene, TRK2. Cells deficient for both high and low affinity K+ transport (trk1 delta trk2) exhibit hypersensitivity to low extracellular pH that can be suppressed by high concentrations of K+ but not Na+. TRK1 completely suppresses both the K+ transport defect and low pH hypersensitivity of trk2 cells, suggesting that TRK1 and TRK2 are functionally independent.

Direct selection for mutants with increased K+ transport in Saccharomyces cerevisiae

Saccharomyces cerevisiae cells containing a deletion of TRK1, the gene encoding the high affinity potassium transporter, retain only low affinity uptake of this ion and consequently lose the ability to grow in media containing low levels (0.2 mM) of potassium. Using a trk1 delta strain, we selected spontaneous Trk+ pseudorevertants that regained the ability to grow on low concentrations of potassium. The revertants define three unlinked extragenic suppressors of trk1 delta. Dominant RPD2 mutations and recessive rpd1 and rpd3 mutations confer increased potassium uptake in trk1 delta cells. Genetic evidence suggests that RPD2 mutations are alleles of TRK2, the putative low affinity transporter gene, whereas rpd1 and rpd3 mutations increase TRK2 activity: (1) RPD2 mutations are closely linked to trk2, and (2) trk2 mutations are epistatic to both rpd1 and rpd3. rpd1 maps near pho80 on chromosome XV and rpd3 maps on the left arm of chromosome XIV, closely linked to kre1.