Quantitative trait locus analysis of contextual fear conditioning in mice

Family, twin and adoption studies provide evidence for a substantial genetic component underlying individual differences in general intelligence, specific cognitive abilities and susceptibility to psychopathologies related to fear-inducing events. Contextual fear conditioning, which is highly conserved across species, can serve as a model for elucidating genes that regulate individual differences in learning and emotion. In fear conditioning, an initially neutral stimulus, such as a tone or a particular environment (context), elicits a fear response after it has been paired with an aversive stimulus, such as shock. Two neural circuits have been implicated in fear conditioning. The fear component is regulated by amygdaloid pathways, while the contextual component is, at least in part, dependent on the hippocampus. C57BL/6J (B6) and DBA/2J (D2) mice differ in several types of complex learning. including contextual fear conditioning. A quantitative trait locus (QTL) analysis of contextual fear conditioning was performed in a B6/D2 F2 intercross population. Two QTLs for contextual conditioning (lod score > 4.3) were identified on chromosomes 10 and 16. QTLs for conditioning to the auditory cue (lod score > 4.3) were localized to chromosomes 1 and 10. Suggestive QTLs (lod score = 2.8-4.1) for contextual conditioning were detected on chromosomes 1, 2 and 3.

LiDCO-based fluid management in patients undergoing hip fracture surgery under spinal anaesthesia: a randomized trial and systematic review

BACKGROUND

Hip fracture is a condition with high mortality and morbidity in elderly frail patients. Intraoperative fluid optimization may be associated with benefit in this population. We investigated whether intraoperative fluid management using pulse-contour analysis cardiac monitoring, compared with standard care in patients undergoing spinal anaesthesia, would provide benefits in terms of reduced time until medically fit for discharge and postoperative complications.

METHODS

Patients undergoing surgical repair of fractured neck of femur, aged >60 yr, receiving spinal anaesthesia were enrolled in this single-centre, blinded, randomized, parallel group trial. Patients were allocated to either anaesthetist-directed fluid therapy or a pulse-contour-guided fluid optimization strategy using colloid (Gelofusine) boluses to optimize stroke volume. The primary outcome was time until medically fit for discharge. Secondary outcomes included postoperative complications, mobility, and mortality. We updated a systematic review to include relevant trials to 2014.

RESULTS

We recruited 130 patients. Time until medically fit for discharge was similar in both groups, mean [95% confidence interval (CI)] 12.2 (11.1-13.5) vs 13.1 (11.9-14.5) days (P=0.31), as was total length of stay 14.2 (12.9-15.8) vs 15.3 (13.8-17.2) days (P=0.32). There were no significant differences in complications, function, or mortality. An updated meta-analysis (four studies, 355 patients) found non-significant reduction in early mortality [relative risk 0.66 (0.24-1.79)] and in-hospital complications [relative risk 0.80 (0.61-1.05)].

CONCLUSIONS

Goal-directed fluid therapy during hip fracture repair under spinal anaesthesia does not result in a significant reduction in length of stay or postoperative complications. There is insufficient evidence to either support or discount its routine use.

CLINICAL TRIAL REGISTRATION

ISRCTN88284896.

The effect of patient ethnicity on the accuracy of peripheral pulse oximetry in patients with COVID-19 pneumonitis: a single-centre, retrospective analysis

Pulse oximetry is used widely to titrate oxygen therapy and for triage in patients who are critically ill. However, there are concerns regarding the accuracy of pulse oximetry in patients with COVID‐19 pneumonitis and in patients who have a greater degree of skin pigmentation. We aimed to determine the impact of patient ethnicity on the accuracy of peripheral pulse oximetry in patients who were critically ill with COVID‐19 pneumonitis by conducting a retrospective observational study comparing paired measurements of arterial oxygen saturation measured by co‐oximetry on arterial blood gas analysis (SaO₂) and the corresponding peripheral oxygenation saturation measured by pulse oximetry (S_pO₂). Bias was calculated as the mean difference between SaO₂ and S_pO₂ measurements and limits of agreement were calculated as bias ±1.96 SD. Data from 194 patients (135 White ethnic origin, 34 Asian ethnic origin, 19 Black ethnic origin and 6 other ethnic origin) were analysed consisting of 6216 paired SaO₂ and S_pO₂ measurements. Bias (limits of agreement) between SaO₂ and S_pO₂ measurements was 0.05% (−2.21–2.30). Patient ethnicity did not alter this to a clinically significant degree: 0.28% (1.79–2.35), −0.33% (−2.47–2.35) and −0.75% (−3.47–1.97) for patients of White, Asian and Black ethnic origin, respectively. In patients with COVID‐19 pneumonitis, S_pO₂ measurements showed a level of agreement with SaO₂ values that was in line with previous work, and this was not affected by patient ethnicity.

Regional analgesia for lower leg trauma and the risk of acute compartment syndrome: Guideline from the Association of Anaesthetists

Pain resulting from lower leg injuries and consequent surgery can be severe. There is a range of opinion on the use of regional analgesia and its capacity to obscure the symptoms and signs of acute compartment syndrome. We offer a multi-professional, consensus opinion based on an objective review of case reports and case series. The available literature suggested that the use of neuraxial or peripheral regional techniques that result in dense blocks of long duration that significantly exceed the duration of surgery should be avoided. The literature review also suggested that single-shot or continuous peripheral nerve blocks using lower concentrations of local anaesthetic drugs without adjuncts are not associated with delays in diagnosis provided post-injury and postoperative surveillance is appropriate and effective. Post-injury and postoperative ward observations and surveillance should be able to identify the signs and symptoms of acute compartment syndrome. These observations should be made at set frequencies by healthcare staff trained in the pathology and recognition of acute compartment syndrome. The use of objective scoring charts is recommended by the Working Party. Where possible, patients at risk of acute compartment syndrome should be given a full explanation of the choice of analgesic techniques and should provide verbal consent to their chosen technique, which should be documented. Although the patient has the right to refuse any form of treatment, such as the analgesic technique offered or the surgical procedure proposed, neither the surgeon nor the anaesthetist has the right to veto a treatment recommended by the other.

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

BACKGROUND

Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.

METHODS

This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low-middle-income countries.

RESULTS

In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of 'single-use' consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low-middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.

CONCLUSION

This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high- and low-middle-income countries.

Influence of propofol-based total intravenous anaesthesia on peri-operative outcome measures: a narrative review

Propofol-based total intravenous anaesthesia is well known for its smooth, clear-headed recovery and anti-emetic properties, but there are also many lesser known beneficial properties that can potentially influence surgical outcome. We will discuss the anti-oxidant, anti-inflammatory and immunomodulatory effects of propofol and their roles in pain, organ protection and immunity. We will also discuss the use of propofol in cancer surgery, neurosurgery and older patients.

The use of LiDCO based fluid management in patients undergoing hip fracture surgery under spinal anaesthesia: neck of femur optimisation therapy - targeted stroke volume (NOTTS): study protocol for a randomized controlled trial

BACKGROUND

Approximately 70,000 patients/year undergo surgery for repair of a fractured hip in the United Kingdom. This is associated with 30-day mortality of 9% and survivors have a considerable length of acute hospital stay postoperatively (median 26 days). Use of oesophageal Doppler monitoring to guide intra-operative fluid administration in hip fracture repair has previously been associated with a reduction in hospital stay of 4-5 days. Most hip fracture surgery is now performed under spinal anaesthesia. Oesophageal Doppler monitoring may be unreliable in the presence of spinal anaesthesia and most patients would not tolerate the probes. An alternative method of guiding fluid administration (minimally-invasive arterial pulse contour analysis) has been shown to reduce length of stay in high-risk surgical patients but has never been studied in hip fracture surgery.

METHODS

Single-centre randomised controlled parallel group trial. Randomisation by website using computer generated concealed tables.

SETTING

University hospital in UK.

PARTICIPANTS

128 patients with acute primary hip fracture listed for operative repair under spinal anaesthesia and aged > 65 years.

INTERVENTION

Stroke volume guided intra-operative fluid management. Continuous measurement of SV recorded by a calibrated cardiac output monitor (LiDCOplus). Maintenance fluid and 250 ml colloid boluses given to achieve sustained 10% increases in stroke volume.

CONTROL GROUP

fluid administration at the responsible (blinded) anaesthetist's discretion. The intervention terminates at the end of the surgical procedure and post-operative fluid management is at the responsible anaesthetist's discretion.

PRIMARY OUTCOME

length of acute hospital stay is determined by a blinded team of clinicians. Secondary outcomes include number of complications and total cost of care. Funding NIHR/RfPB: PB-PG-0407-13073.

TRIAL REGISTRATION NUMBER

TRIAL REGISTRATION

Current Controlled Trials ISRCTN88284896.

The glochidia of certain Unionidae (Mollusca) in Nova Scotia and their fish hosts

Morphological and morphometric comparisons among adult and glochidial unionids from two Nova Scotian locations showed that Anodonta implicata, A. cataracta cataracta, A. c. fragilis, Elliptio complanatus, and Lampsilis radiata radiata were present. Gravidity studies suggested that fully developed glochidia occur from September to May in Anodonta marsupia, for only 5–6 weeks in June and July in E. complanatus, and perhaps at least from spring to early fall in L. r. radiata. Seven of 12 fish species sampled bore glochidia, which were identified in five host species by comparisons of their shapes and dimensions with those of glochidia from adult clams. Results were as follows: A. c. cataracta in Catostomus commersoni in June only, A. implicata or A. c. cataracta in Gasterosteus aculeatus in May and June, Anodonta sp. in Apeltes quadracus and Pungitius pungitius in June, and E. complanatus in Fundulus diaphanus in June and July. Thus, no relationships between gravidity periods of adult clams and infestation periods of their fish hosts by their glochidia were evident for species of Anodonta.

Adherent neutrophils mediate permeability after atelectasis

Re-expansion of atelectatic lung is associated with increased permeability. This study tests whether neutrophils mediate this event. Right middle lobar atelectasis was induced in anesthesized rabbits (n = 18) by intraluminal obstruction of the bronchus after a 20-minute ventilation with 100% O2. After 1 hour of bronchial obstruction and 20 minutes after lobar re-expansion, leukopenia was noted, 2870 +/- 210 white blood cells (WBC)/mm3, relative to control animals treated with a noninflated balloon catheter, 6500 +/- 410 WBC/mm3 (p less than 0.05). Three hours after re-expansion, neutrophils were sequestered in the previously atelectatic region 78 +/- 7 polymorphonuclear leukocytes (PMN)/10 high-power field (HPF), as well as in nonatelectatic areas, 40 +/- 3 PMN/10 HPF, higher than control values of 26 +/- 3 PMN/10 HPF (p less than 0.05). In the atelectatic region, neutrophil sequestration was associated with increased protein concentration in lobar bronchoalveolar lavage (BAL) of 1370 +/- 100 micrograms/mL, higher than control values of 270 +/- 20 micrograms/mL (p less than 0.05). Reexpansion also induced increases in lung wet-to-dry weight ratio (W/d) of 6.2 +/- 0.2, higher than control values of 4.3 +/- 0.1 (p less than 0.05). Rendering rabbits neutropenic (n = 18) (0 to 4 PMN/mm3) limited the atelectasis-induced protein accumulations in BAL (520 +/- 60 micrograms/mL) and increase in lung W/d (5.2 +/- 0.1) (both p less than 0.05). Intravenous (I.V.; treatment of another group (n = 18) with an anti-CD 18 monoclonal antibody (R 15.7, 1 mg/kg) before balloon deflation prevented leukopenia (6550 +/- 560 WBC/mm3), minimized neutrophil sequestration (36 +/- 2 PMN/10 HPF), and attenuated protein leak (710 +/- 95 micrograms/mL) and the increased lung W/d (5.6 +/- 0.1) (all p less than 0.05). A final atelectatic group (n = 9) was treated I.V. with the anti-intercellular adhesion molecule-1 monoclonal antibody (RR 1/1, 1 mg/kg), which also prevented leukopenia and showed similar protection of microvascular barrier function. These data indicate that adherent neutrophils in large part mediate lung permeability and edema after atelectasis and re-expansion. Adhesion receptors of both neutrophils and endothelial cells regulate this event.

The occurrence of Diplozoon paradoxum Nordmann, 1832 (Trematoda: Mongenea) in certain waters of northern England and its distribution on the gills of certain Cyprinidae

The monogenean Diplozoon paradoxum occurs on Abramis brama, Gobio gobio, Phoxinus phoxinus and Rutilus rutilus in northern England. In any one area, the infection is present in some waters but absent in others and predominates in rivers rather than in ponds or reservoirs.

D. paradoxum is randomly distributed on the gills, sides of the gill apparatus, hemibranchs and surfaces of primary lamellae of G. gobio, P. phoxinus and R. rutilus (except for P. phoxinus where inner hemibranchs carry more worms), but prevails on median sectors of the gills of these hosts. In A. brama the parasite is more numerous on certain gills, on the right side of the gill apparatus, and on the inner hemibranchs, but is randomly disposed on primary lamellar surfaces and along the gills. Except on G. gobio attachment is predominantly to two primary lamellae rather than one. This may reduce dislodging effects of the gill ventilating current by leaving portions of the lamellar surfaces unoccupied and allowing unimpeded flow in these regions.

This work was conducted during tenure of a Science Research Council Research Studentship. Research facilities in the Department of Zoology, University of Leeds, were kindly provided by Professor J. M. Dodd. Other facilities in the Biological Station, St John's, Newfoundland, were provided by the Director, Dr W. Templeman. Statistical advice offered by Dr E. Broadhead, Department of Zoology, and Professor C. L. Oakley, Department of Bacteriology, both of the University of Leeds, is gratefully acknowledged. I am indebted to Dr R. Wynne Owen, Department of Zoology, for constant advice and encouragement and for critical reading of the manuscript.

Targeted temperature management in patients with intracerebral haemorrhage, subarachnoid haemorrhage, or acute ischaemic stroke: updated consensus guideline recommendations by the Neuroprotective Therapy Consensus Review (NTCR) group

BACKGROUND

There is a lack of consistent, evidence-based guidelines for the management of patients with fever after brain injury. The aim was to update previously published consensus recommendations on targeted temperature management after intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in patients who require admission to critical care.

METHODS

A modified Delphi consensus, the Neuroprotective Therapy Consensus Review (NTCR), included 19 international neuro-intensive care experts with a subspecialty interest in the acute management of intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke. An online, anonymised survey was completed ahead of the meeting before the group came together to consolidate consensus and finalise recommendations on targeted temperature management. A threshold of ≥80% for consensus was set for all statements.

RESULTS

Recommendations were formulated based on existing evidence, literature review, and consensus. After intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in patients who require critical care admission, core temperature should ideally be monitored continuously and maintained between 36.0°C and 37.5°C using automated feedback-controlled devices, where possible. Targeted temperature management should be commenced within 1 h of first fever identification with appropriate diagnosis and treatment of infection, maintained for as long as the brain remains at risk of secondary injury, and rewarming should be controlled. Shivering should be monitored and managed to limit risk of secondary injury. Following a single protocol for targeted temperature management across intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke is desirable.

CONCLUSIONS

Based on a modified Delphi expert consensus process, these guidelines aim to improve the quality of targeted temperature management for patients after intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in critical care, highlighting the need for further research to improve clinical guidelines in this setting.

The effect of a new topical local anaesthetic delivery system on forearm skin blood flow reactivity

Different topical local anaesthetics have varying effects on skin blood flow and vascular reactivity. We compared the vasoactive properties of Rapydan, a new topical local anaesthetic, with those of Ametop and EMLA creams in 20 healthy volunteers. Blood flow and vascular reactivity in the forearm skin were assessed by laser Doppler flowmetry and the transient hyperaemic response ratio respectively, before and after the application of EMLA (for 60 min), Ametop (for 30 and 60 min) and Rapydan (for 30 min). Application of EMLA had no effect on skin blood flow (median (IQR [range]) change from baseline -0.9% (-63 to 414 [-38.5 to 51.3] %, p = 1.0)) or mean (SD) transient hyperaemic response ratio (from 2.86 (0.86) to 3.17 (1.3), p = 0.38). The application of Ametop for 60 min produced a greater median (IQR [range]) increase in blood flow from baseline (508 (-55 to 998 [148-649]) %) than Rapydan applied for 30 min 160 (-77 to 997 [45-301]) %, p = 0.001), and a similar decrease in mean (SD) transient hyperaemic response ratio (from 2.69 (1.16) to 1.08 (0.26) and from 2.83 (0.84) to 1.49 (0.93) respectively, p = 0.57).

Airway management in patients with suspected or confirmed traumatic spinal cord injury: a narrative review of current evidence

Around 1 million people sustain a spinal cord injury each year, which can have significant psychosocial, physical and socio‐economic consequences for patients, their families and society. The aim of this review is to provide clinicians with a summary of recent studies of direct relevance to the airway management of patients with confirmed or suspected traumatic spinal cord injury to promote best clinical practice. All airway interventions are associated with some degree of movement of the cervical spine; in general, these are very small and whether these are clinically significant in terms of impingement of the spinal cord is unclear. Manual in‐line stabilisation does not effectively immobilise the cervical spine and increases the likelihood of difficult and failed tracheal intubation. There is no clear evidence of benefit of awake tracheal intubation techniques in terms of prevention of secondary spinal cord injury. Videolaryngoscopy appears to cause a similar degree of cervical spine displacement as flexible bronchoscope‐guided tracheal intubation and is an appropriate alternative approach. Direct laryngoscopy does cause a slightly greater degree of cervical spinal movement during tracheal intubation than videolaryngoscopy, but this does not appear to increase the risk of spinal cord compression. The risk of spinal cord injury during tracheal intubation appears to be minimal even in the presence of gross cervical spine instability. Depending on the clinical situation, practitioners should choose the tracheal intubation technique with which they are most proficient and that is most likely to minimise cervical spine movement.

Parasites of Fundulus diaphanus (LeSueur) (Pisces: Cyprinodontidae) in certain Nova Scotian freshwaters

Over 90% of 829 banded killifish from three Nova Scotian locations were infected with at least one parasitic species. Protozoans, monogeneans, digeneans, cestodes, nematodes, acanthocephalans, and a crustacean and a molluscan species occurred in the fish. All species recovered are reported for the first time from Fundulus diaphanus in Nova Scotia and 12 are new host records. Five of the non-digenean larval genera found were probably accidental parasites.

The numerical translation of verbal probability expressions by patients and clinicians in the context of peri-operative risk communication

Shared decision-making is central to the pre-operative consent process and accurate communication of risk is dependent on a clear understanding of numerical information by both the patient and clinician. The risk of an adverse event or complication is often described using verbal probability expressions but how these are interpreted by clinicians and patients in the pre-operative setting has not been studied. We asked patients and clinicians to assign a numerical translation (as a percentage) for seven verbal probability expressions in relation to the probability of a major peri-operative complication occurring. In total, data from 290 patients and 57 clinicians were analysed. There was a wide range in percentages assigned by patients to all verbal probability expressions. Patients assigned a wider range of percentage values to each of the verbal probability expressions and these were all significantly higher than those assigned by clinicians: median (IQR [range]) negligible risk 5% (1-15 [0-100]) vs. 0% (0-0 [0-5]); minimal risk 5% (2-10) [0-100]) vs. 1% (0-1 [0-10]); low risk 10% (3-10 [0-100]) vs. 1% (0-2) [0-10]); standard risk 20% (10-40) [0-100]) vs. 1% (1-5) [0-30]); moderate risk 33% (20-50) [0-100]) vs. 5% (3-10) [0-80]); high risk 70% (30-90 [0-100]) vs. 15% (10-40) [1-75]); and very high risk 90% (50-95 [0-100]) vs. 40% (20-50 [5-100]), respectively (p < 0.005 for all comparisons). There is considerable variation in the numerical translation of verbal probability expressions by both patients and clinicians. This suggests that verbal probability expressions should not be used in isolation as part of doctor-patient discussions regarding peri-operative risk.

Positioning a proned patient with cauda equina syndrome who presents at 15 weeks gestation: a case report

Cauda equina syndrome is a neurosurgical emergency that requires prompt intervention to prevent irreversible spinal cord paralysis. This article describes how we managed a case of an obese pregnant patient who was placed in the prone position for surgery. We discuss the evidence behind the management options and choice of operating tables available.

Position statement from the Editors of Anaesthesia and Anaesthesia Reports on best practice in academic medical publishing

It is essential that academic publishing complies with the highest standards in terms of ethics, research conduct and manuscript preparation. This protects the rights and welfare of research participants, ensures the integrity of study results and aids the communication and dissemination of novel findings into clinical practice. This position statement outlines the current policies and practices of the Editors of Anaesthesia and Anaesthesia Reports in relation to academic medical publishing.

The Pathophysiology of Early Hypotension Following Epinephrine-containing Local Anesthetic Infiltration of the Nasal Mucosa in Patients Undergoing Endoscopic Transsphenoidal Hypophysectomy: A Prospective, Observational Study

In patients undergoing endoscopic transsphenoidal hypophysectomy, the nasal mucosa is often infiltrated with local anesthetic solutions that contain epinephrine to aid hemostasis. This may, however, result in hemodynamic changes, especially hypotension. We characterized the cardiovascular changes using a LiDCOrapid monitor in 13 patients after the infiltration of 4% articaine containing 1:200,000 epinephrine. Nine (69%) had a >20% decrease in mean arterial pressure at a median time of 116 seconds after the infiltration of articaine with epinephrine. Analysis of the cardiac output data revealed that this was caused by a sustained reduction in systemic vascular resistance. The arterial blood pressure normalized over a period of 60 to 90 seconds secondary to increases in stroke volume and heart rate producing an elevation in cardiac output. Transient hypotension following the infiltration of epinephrine-containing local anesthetics may be caused by epinephrine stimulation of β2-adrenoceptors producing vasodilation.