Tourniquet-induced nerve compression injuries are caused by high pressure levels and gradients - a review of the evidence to guide safe surgical, pre-hospital and blood flow restriction usage

Effect of One Session of Muscle Blood Flow Restriction Training Versus Normal Training on Blood Lactate Level

Objectives

Blood flow restriction training (BFRT) is useful for improving muscle strength. However, it involves a long training time and is unsuitable for vigorous exercise. Muscle blood flow restriction training (MBFRT), which uses multiple parallel pneumatic cuffs (MPCs) to compress large areas of the extremities and restrict blood flow, was subsequently developed to address these issues. This study compared the effects of MBFRT with normal training (NT).

Methods

Ten healthy adults underwent low-intensity MBFRT. MPC pressure was increased to 200 mmHg just before training. The exercise was a bodyweight half-squat. Three sets of 30 squats were performed. Two weeks later, the participants underwent NT with the same exercise. Blood lactate levels were measured before the start of training and at 1 and 5 min after training. The Borg index was also measured at the end of the training.

Results

The blood lactate level was elevated at 1 min after MBFRT and NT. The elevated blood lactate level was maintained at 5 min after MBFRT, whereas the lactate level was significantly decreased at 5 min after NT. The Borg index at the end of the training was significantly higher in MBFRT than in NT.

Conclusions

Lactic acid accumulates in the muscles during low-intensity MBFRT, thereby initiating type II fiber activity.

A systematic review of tourniquet use in paediatric orthopaedic surgery: can we extrapolate from adult guidelines?

Purpose

Tourniquets are commonly used intraoperatively in orthopaedic surgery to control bleeding and improve visibility in the surgical field. Recent evidence has thrown into question the routine use of tourniquets in the adult population resulting in a British Orthopaedic Association standard for intraoperative use. This systematic review evaluates the evidence on the practice, benefits, and risks of the intraoperative use of tourniquets for trauma and elective orthopaedic surgery in the paediatric population.

Methods

A prospectively registered systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO: CRD42022359048). A search of MEDLINE, Embase, the Cochrane Library and a Grey literature search was performed from their earliest record to 23 March 2023. Studies reporting tourniquet data in paediatric patients undergoing orthopaedic surgery were included. Data extracted included demographics, involved limb, trauma versus elective use, tourniquet use as primary or secondary measure, and tourniquet parameters and complications.

Results

Thirty-nine studies were included. Tourniquet practices and information reporting varied considerably. Tourniquets were used uneventfully in the majority of patients with no specific benefits reported. Several physiological and biochemical changes as well as complications including nerve injury, compartment syndrome, skin burns, thrombosis, post-operative limb swelling, and pain were reported.

Conclusions

Tourniquets are routinely used in both trauma and elective paediatric orthopaedic surgery with no high-quality research affirming benefits. Severe complications associated with their use are rare but do occur. High-quality studies addressing their benefits, the exact indication in children, and the safest way to use them in this population are necessary.

Tourniquet-Related Nerve Injury Following Reconstructive Surgery for Wassel Type IV Preaxial Polydactyly of 13-Year-Old Boy: A Case Report

BACKGROUND Congenital thumb duplication comes under the Wassel type IV classification is the hypoplastic variety, with the extra digit growing from the dominant thumb's soft tissue alone. Excising the hypoplastic finger while reconstructing for the retained one has been the most adopted approach. Tourniquets are commonly utilized tools in orthopedic surgeries to reduce the amount of blood, thus enhancing the visibility. Unfortunately, tourniquet-related nerve injury (TNRI) is gaining more attention as a serious complication of tourniquet use in surgery. CASE REPORT A 13-year-old Asian boy with preaxial polydactyly Wassel type IV of the right hand underwent reconstruction surgery. A pneumatic tourniquet was applied at 200 mmHg on the right mid-upper arm and maintained for 90 min. After the surgery, the patient had total weakness with numbness, tingling, and burning sensation from his right upper arm to his fingertips. The neurological examination and nerve conduction studies (NCS) results were consistent with axonotmesis lesions. Pharmacological and physical rehabilitation therapy had successfully restored full motoric and sensory function after 6 months. CONCLUSIONS Nerve injury should be acknowledged as a possible complication from routinely-utilized tourniquets in orthopedic surgeries. Our cases may expand the need for further studies to establish a guideline for tourniquet use and TRNI management.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part B (Nerve Injury Types, Mechanisms, and Pathogenesis)

Selander emphatically said, "Handle these nerves with care," and those words still echo, conveying a loud and clear message that, however rare, peripheral nerve injury (PNI) remains a perturbing possibility that cannot be ignored. The unprecedented nerve injuries associated with peripheral nerve blocks (PNBs) can be most tormenting for the unfortunate patient and a nightmare for the anesthetist. Possible justifications for the seemingly infrequent occurrences of PNB-related PNIs include a lack of documentation/reporting, improper aftercare, or associated legal implications. Although they make up only a small portion of medicolegal claims, they are sometimes difficult to defend. The most common allegations are attributed to insufficient informed consent; preventable damage to a nerve(s); delay in diagnosis, referral, or treatment; misdiagnosis, and inappropriate treatment and follow-up care. Also, sufficient prospective studies or randomized trials have not been conducted, as exploring such nerve injuries (PNB-related) in living patients or volunteers may be impractical or unethical. Understanding the pathophysiology of various types of nerve injury is vital to dealing with them further. Processes like degeneration, regeneration, remyelination, and reinnervation can influence the findings of electrophysiological studies. Events occurring in such a process and their impact during the assessment determine the prognosis and the need for further interventions. This educational review describes various types of PNB-related nerve injuries and their associated pathophysiology.

Guidelines for Wide-Awake Local Anesthesia Surgery with No Tourniquet in the Office Setting Using Field Preparation Sterility

SUMMARY

Wide-awake local anesthesia surgery with no tourniquet, or WALANT, has become popular in surgery, especially among hand surgeons. With the increasing number of surgeons performing office-based procedures, this article provides guidelines that may be used in the office setting to help transition more traditional hospital operating room-based procedures to the office setting. This article outlines the benefits of performing office-based wide-awake local anesthesia surgery with no tourniquet and provides a step-by-step guide to performing procedures that can be easily incorporated into any hand surgeon's practice successfully and safely.

Optimization of surgical tourniquet usage to improve patient outcomes: Translational cross-disciplinary implications of a surgical practice survey

Tourniquet use is common practice in many millions of orthopaedic procedures annually. Recent reviews of risks and benefits of surgical tourniquet use have primarily involved meta-analyses, many of which have forgone a comprehensive risk-benefit analysis to simply question whether "tourniquet or no tourniquet" use produces improved patient outcomes, often leading to limited, inconclusive, or conflicting results. To investigate further, a pilot survey was undertaken to determine current practices, opinions, and understandings among orthopaedic surgeons in Canada regarding use of surgical tourniquets in total knee arthroplasties (TKAs). Results of the pilot survey showed a wide range of understanding and practice associated with tourniquet use in TKAs, especially regarding tourniquet pressures and tourniquet times, two key factors known from basic research and clinical studies to impact the safety and efficacy of tourniquet use. The wide variation of use indicated by the survey results reveals important implications for surgeons, researchers, educators, and biomedical engineers, to better understand the association between key tourniquet parameters and outcomes assessed in research, which may be factors leading to their often limited, inconclusive, and conflicting results. Lastly, we provide an overview of the overly simplified assessments of tourniquet use in meta-analyses, whose conclusions may not provide an understanding of how or whether key tourniquet parameters might be optimized to retain the benefits of tourniquet use while mitigating the associated real or perceived risks.

A single-center, nonblinded, clinical trial comparing blood pressures before and after tourniquet application in healthy humans: A study protocol

INTRODUCTION

Cardiac arrest is the leading cause of natural death in the United States, and most surviving patients suffer from neurological dysfunction. Although this is recognized as a problem, there have been very few changes to the cardiopulmonary resuscitation (CPR) procedure. Tourniquets have been recognized for their ability to increase truncal blood pressure and have been shown to improve CPR outcomes in animal models. However, the relationship between tourniquet application and blood pressure elevation has not been adequately explored in healthy human adults.

OBJECTIVES

The objective of this study is to demonstrate that bilateral, non-invasive, peripheral vascular occlusion in the thighs results in an increased proximal systolic blood pressure ≥ 10 mmHg.

METHODS

This is a single-center, non-blinded clinical trial. Volunteers will be screened for eligibility at least 24 hours before the day of the trial. On the day of the trial, volunteers will undergo an informed consent process. If they choose to participate in the trial after informed consent, their baseline blood pressure will be measured. Volunteers will then have a Combat Application Tourniquet (CAT) applied to each thigh, and the windlasses will be tightened by IRB-approved personnel. Once no pulse can be felt in the lower extremity, blood pressure will be measured in the arm. This will be replicated three times, and the tourniquets will be loosened between trials to allow the volunteers to rest. Any complications that arise during the trial will be handled by the physician that is present.

ANALYSIS

Changes in systolic blood pressure and diastolic blood pressure will be analyzed using a Shapiro-Wilk test. Then, a one-way repeated measures analysis of variance (ANOVA) will be performed with a Holm-Sidak post-hoc test to determine the mean differences. The significance level will be set to 5% for statistical significance.

REGISTRY AND REGISTRATION NUMBER

Clinicaltrials.gov, NCT05324306.

Pre-operative Blood Loss Prediction Formulas in Burn Surgeries: A Review

Extensive burn surgeries lead to a considerable amount of blood loss. Predicting pre-operative blood loss is essential for blood ordering and crossmatching. Accurate amount of ordered blood units ensures patients' safety and minimizes cost. However, blood loss estimation is complicated due to a variety of factors influencing blood loss, including patient and operative-related variables. Currently, no standard method to predict blood loss exists prior to surgery. Our goal is to review factors influencing blood loss and formulas that can predict blood loss. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE databases for studies investigating blood loss in burn surgeries with a clear quantitative outcome. Fifteen studies were included, comprising 1613 subjects. All studies calculated blood loss and assessed possible related factors, and four studies proposed preoperative blood loss prediction formulas. Larger areas of tissue excised and grafted, younger age, and delayed surgery were correlated with increased blood loss. Varying decrease in blood loss was observed with tumescent usage and other bleeding control methods. Other variables produced inconsistent results. From four prediction formulas, only one formula, Dye's Formula, had been applied and proven effective in reducing unused blood units clinically by up to 40% of cross-matched blood. Various confounding factors and dissimilarities between studies make reliable prediction method construction challenging. With consideration of diverse patient characteristics, some study develops formulas to achieve optimal patient care and avoid unnecessary hospital expenditure. Further research with consistent variables should be done to construct a standardized blood loss estimation formula.

Beneficial Role of Blood Flow Restriction Exercise in Heart Disease and Heart Failure Using the Muscle Hypothesis of Chronic Heart Failure and a Growing Literature

Background: Blood flow restriction exercise (BFRE) has become a common method to increase skeletal muscle strength and hypertrophy for individuals with a variety of conditions. A substantial literature of BFRE in older adults exists in which significant gains in strength and functional performance have been observed without report of adverse events. Research examining the effects of BFRE in heart disease (HD) and heart failure (HF) appears to be increasing for which reason the Muscle Hypothesis of Chronic Heart Failure (MHCHF) will be used to fully elucidate the effects BFRE may have in patients with HD and HF highlighted in the MHCHF.

Methods: A comprehensive literature review was performed in PubMed and the Cochrane library through February 2022. Inclusion criteria were: 1) the study was original research conducted in human subjects older than 18 years of age and diagnosed with either HD or HF, 2) study participants performed BFRE, and 3) post-intervention outcome measures of cardiovascular function, physical performance, skeletal muscle function and structure, and/or systemic biomarkers were provided. Exclusion criteria included review articles and articles on viewpoints and opinions of BFRE, book chapters, theses, dissertations, and case study articles.

Results: Seven BFRE studies in HD and two BFRE studies in HF were found of which four of the HD and the two HF studies examined a variety of measures reflected within the MHCHF over a period of 8–24 weeks. No adverse events were reported in any of the studies and significant improvements in skeletal muscle strength, endurance, and work as well as cardiorespiratory performance, mitochondrial function, exercise tolerance, functional performance, immune humoral function, and possibly cardiac performance were observed in one or more of the reviewed studies.

Conclusion: In view of the above systematic review, BFRE has been performed safely with no report of adverse event in patients with a variety of different types of HD and in patients with HF. The components of the MHCHF that can be potentially improved with BFRE include left ventricular dysfunction, inflammatory markers, inactivity, a catabolic state, skeletal and possibly respiratory muscle myopathy, dyspnea and fatigue, ANS activity, and peripheral blood flow. Furthermore, investigation of feasibility, acceptability, adherence, adverse effects, and symptoms during and after BFRE is needed since very few studies have examined these important issues comprehensively in patients with HD and HF.

Predicting surgical factors for unplanned overnight admission in ambulatory arthroscopic surgery of the knee: a prospective cohort in one hundred and eighty four patients

PURPOSE

Unplanned overnight admission (UOA) is an important indicator for quality of care with ambulatory knee arthroscopic surgery (AKAS). However, few studies have explored the factors related to the UOA and how to predict UOA after AKAS. This study aimed to evaluate the effectiveness of a standardized peri-operative protocol for the AKAS and identify whether a correlation exists between the peri-operative surgical factors and UOA in the patients undergoing AKAS. We hypothesized that more surgical invasiveness and prolong tourniquet time increase the risk of UOA after AKAS.

METHOD

A prospective cohort study was conducted between October 2017 and March 2021. All 184 patients operated on standard AKAS protocol. The UOA is defined as overnight hospitalization of a patient undergoing AKAS. Demographic and peri-operative data were recorded, and the procedure was categorized based on the surgical invasiveness based on less invasive (intra-articular soft tissue surgery) (n = 65) and more complex surgery (involving extra-articular soft tissue surgery or ligamentous reconstruction) (n = 119). The clinical risk factors for UOA were identified and analyzed with multivariate analysis.

RESULTS

The incidence of UOA in the more complex group (n = 7, 14.3%) was significantly higher than in the less invasive group (n = 3, 4.6%) (p = 0.049). The peri-operative factors significantly associated with UOA were age, more complex surgery, and longer tourniquet time (p < 0.10 all). However, the multivariate analysis revealed that longer tourniquet time was the only significant predictor for UOA (OR = 1.045, 95% CI = 1.022-1.067, p = 0.0001). The optimal cut-off points of tourniquet time for predicting UOA with the highest Youden index in the less invasive and more complex groups were 56 minutes and 107 minutes, respectively.

CONCLUSION

The UOA after AKAS is more common in more complex surgery compared to less invasive surgery. This study showed that unplanned admission significantly associated with many factors-as patient factors, surgical invasiveness, and tourniquet time. However, tourniquet time is the only independent predictor for UOA. Therefore, strict perioperative management protocol must be applied in AKAS, and all patients having these risk factors should be prepared for UOA.

Prehospital Tourniquets Placed on Limbs Without Major Vascular Injuries, has the Pendulum Swung Too far?

BACKGROUND

Combat applications of tourniquets for extremity trauma have led to increased civilian prehospital tourniquet use. Studies have demonstrated that appropriate prehospital tourniquet application can decrease the incidence of arrival in shock without increasing limb complications. The aim of this study was to examine outcomes of prehospital tourniquet placement without definitive vascular injury.

METHODS

Retrospective review was performed of a prospectively maintained database by the American Association for the Surgery of Trauma from 29 trauma centers. Patients in this subset analysis did not have a significant vascular injury as determined by imaging or intra-operatively. Patients who received prehospital tourniquets (PHTQ) were compared to patients without prehospital tourniquets (No-PHTQ). Outcomes were amputation rates, nerve palsy, compartment syndrome, and in-hospital mortality.

RESULTS

A total of 622 patients had no major vascular injury. The incidence of patients without major vascular injury was higher in the PHTQ group (n = 585/962, 60.8 vs n = 37/88, 42.0%, P < .001). Cohorts were similar in age, gender, penetrating mechanism, injury severity scores (ISS), abbreviated injury score (AIS), and mortality (P > .05). Amputation rates were 8.3% (n = 49/585) in the PHTQ group compared to 0% (n = 0/37) in the No-PHTQ group. Amputation rates were higher in PHTQ than No-PHTQ with similar ISS and AIS (P = .96, P = .59). The incidence of nerve palsy and compartment syndrome was not different (P > .05).

CONCLUSIONS

This study showed a significant amount of prehospital tourniquets are being placed on patients without vascular injuries. Further studies are needed to elucidate the appropriateness of prehospital tourniquets, including targeted education of tourniquet placement.

Development and Characterization of a Self-Tightening Tourniquet System

Uncontrolled hemorrhage remains a leading cause of death in both emergency and military medicine. Tourniquets are essential to stopping hemorrhage in these scenarios, but they suffer from subjective, inconsistent application. Here, we demonstrate how tourniquet application can be automated using sensors and computer algorithms. The auto-tourniquet self-tightens until blood pressure oscillations are no longer registered by the pressure sensor connected to the pneumatic pressure cuff. The auto-tourniquet's performance in stopping the bleed was comparable to manual tourniquet application, but the time required to fully occlude the bleed was longer. Application of the tourniquet was significantly smoother, and less variable, for the automatic tourniquet compared to manual tourniquet application. This proof-of-concept study highlights how automated tourniquets can be integrated with sensors to provide a much more consistent application and use compared to manual application, even in controlled, low stress testing conditions. Future work will investigate different sensors and tourniquets to improve the application time and repeatability.

Supervisory Algorithm for Autonomous Hemodynamic Management Systems

Future military conflicts will require new solutions to manage combat casualties. The use of automated medical systems can potentially address this need by streamlining and augmenting the delivery of medical care in both emergency and combat trauma environments. However, in many situations, these systems may need to operate in conjunction with other autonomous and semi-autonomous devices. Management of complex patients may require multiple automated systems operating simultaneously and potentially competing with each other. Supervisory controllers capable of harmonizing multiple closed-loop systems are thus essential before multiple automated medical systems can be deployed in managing complex medical situations. The objective for this study was to develop a Supervisory Algorithm for Casualty Management (SACM) that manages decisions and interplay between two automated systems designed for management of hemorrhage control and resuscitation: an automatic extremity tourniquet system and an adaptive resuscitation controller. SACM monitors the required physiological inputs for both systems and synchronizes each respective system as needed. We present a series of trauma experiments carried out in a physiologically relevant benchtop circulatory system in which SACM must recognize extremity or internal hemorrhage, activate the corresponding algorithm to apply a tourniquet, and then resuscitate back to the target pressure setpoint. SACM continues monitoring after the initial stabilization so that additional medical changes can be quickly identified and addressed, essential to extending automation algorithms past initial trauma resuscitation into extended monitoring. Overall, SACM is an important step in transitioning automated medical systems into emergency and combat trauma situations. Future work will address further interplay between these systems and integrate additional medical systems.

Effects of Folinic Acid Administration on Lower Limb Ischemia/Reperfusion Injury in Rats

Surgery under ischemic conditions, lasting up to 3 h, is routinely performed in orthopedic surgery, causing undesirable injury due to ischemia-reperfusion syndrome, with short and medium-term functional repercussions. To date, there is no established prophylactic treatment. In this work we evaluated folinic acid (FA) in a rodent model of lower limb ischemia-reperfusion (IRI-LL). 36 male WAG rats underwent 3 h of lower limb ischemia. In the saline group, rats received intraperitoneal administration of saline (used as vehicle for treatment). In the experimental group, rats were pretreated with FA (2.5 mg/kg) before the end of ischemia. After ischemia, animals were sacrificed at 3 h, 24 h or 14 days (for biochemical determination (Na+, K+, Cl-, urea, creatinine, CK, LDH, ALP, ALT, and AST), pathological assessment, or functional study using the rotarod test; respectively). Another six animals were used to establish the reference values. The prophylactic administration of FA significantly reduced the elevation of biochemical markers, especially those that most directly indicate muscle damage (CK and LDH). In addition, it also improved direct tissue damage, both in terms of edema, weight, PMN infiltrate and percentage of damaged fibers. Finally, the administration of FA allowed the animals to equal baseline values in the rotarod test; what did not occur in the saline group, where pre-ischemia levels were not recovered. Following 3 h of lower limb ischemia, FA minimizes the increase of CK and LDH, as well as local edema and leukocyte infiltration, allowing a faster recovery of limb functionality. Therefore, it could be considered as a prophylactic treatment when tourniquet is used in clinics.

Therapeutic effects of masitinib on abnormal mechanoreception in a mouse model of tourniquet-induced extremity ischemia-reperfusion

Tourniquets are widely used to stop extremity hemorrhage, but their use and subsequent release can result in nerve damage and degeneration, leading to neurological deficits. Increasing evidence has suggested a pivotal role of inflammation in nerve damage and abnormal mechanoreception. In this study, we investigated the therapeutic effects of masitinib (Mas), an anti-neuroinflammatory drug, on the mechanoreception of sensory neurons in a mouse model of tourniquet-induced hind paw ischemia-reperfusion (tourniquet/IR). C57BL/6 mice were subjected to 3 h of ischemia by placing a rubber band at the ankle joint and evaluated for subsequent reperfusion injury on day 1, 3, 7, 14, and 28 based on the experiments. Treatment with Mas (28 mg/kg/day, i.p.) began on the day of IR induction and lasted for 1, 3, 7, 14, or 28 days. Tourniquet/IR caused sensory nerve denervation in the skin of paw pads and abolished the hind paw mechanoreception to mechanical stimulation during the first 3 days of reperfusion. Sensory nerves gradually reinnervated in the skin of paw pads and allodynia began to appear on day 7. The maximum reaction occurred on day 14 and was maintained throughout the study period. Treatment with Mas mitigated nerve damage and improved hind paw mechanoreception to mechanical stimulation by decreasing the production of reactive oxygen species (ROS) during the early stages of tourniquet/IR. Mas also alleviated allodynia and decreased inflammatory cytokines (IL-1β and TNFα) in the skin of paw pads from days 7-28. Our data suggest that treatment with Mas significantly ameliorated paw numbness and allodynia in mouse hind paw tourniquet/IR.

A reproducible method for biochemical, histological and functional assessment of the effects of ischaemia-reperfusion syndrome in the lower limbs

Current methodology described to mimic lower limb ischaemia-reperfusion injury (LL-IRI) does not accurately define the procedures and pressures exerted to induce and maintain ischaemia. In this piece of work, we propose a well-defined and detailed rat model that simulates the conditions established in clinical practice guidelines for tourniquet application and allows us to test treatments that aim to prevent/reduce LL-IRI. Eighty-six male WAG/RijHsd rats were subjected to hind limb IRI (LL-IRI), using a mechanical system applying a 1 kg tension to induce and maintain ischemia for 2 or 3 h, and assessed the damage caused by reperfusion at biochemical and muscular levels at different time points. At the biochemical level, both 2 and 3 h of ischemia induced changes (except for electrolyte levels); 3 h of ischemia induced greater changes in specific markers of muscular damage: creatine kinase (CK) and lactate dehydrogenase (LDH). At the histopathological level, 3 h of ischemia and 24 h of reperfusion was associated with an increase in hind limb girth, cross-sectional area, and weight and presence of neutrophils, as well as histological damage in more than 60% of muscle fibres. Our model allows to reliably reproduce the damage associated with the use of a pneumatic tourniquet. CK and LDH, as well as measures of tissue damage, allow to define and characterize the response to LL-IRI-related damage. A period of 3 h of ischemia followed by 3 h of reperfusion caused only local damage but showed greater sensitivity to detect differences in future studies on prophylactic treatments against LL-IRI.

Enzymatically triggered graphene oxide released from multifunctional carriers boosts anti-pathogenic properties for promising wound-healing applications

Spurred by recent progress in biomaterials and therapeutics, stimulus-responsive strategies that deliver an active substance in temporal-, spatial-, and dose-controlled fashions have become achievable. Implementation of such strategies necessitates the use of bio-safe materials that are sensitive to a specific pathological incitement or that, in response to a precise stimulus, undergo hydrolytic cleavage or a change in biomolecular conformation. An innovative design of polymeric stimulus-responsive systems should controllably release a drug or degrade the drug carrier in response to specific lesion enzymes. Wound healing is a great challenge due to various hidden factors such as pathogenic infections, neurovascular diseases, excessive exudates, lack of an effective therapeutic delivery system, low cell proliferation, and cell migration. In addition, long-term use of antibiotics in chronic wound management can result in side effects and antimicrobial resistance. Novel treatments with antibacterial pharmaceuticals thus vitally need to be developed. Recently, graphene and graphene family members have emerged as shining stars among biomaterials for wound-healing applications due to their excellent bioactive properties, which can overcome limitations of current wound dressings and fulfill wound-healing requirements. Herein, we developed a feasible approach to impregnate graphene oxide (GO) into genipin-crosslinked gelatin (3GO) hydrogels to enzymatically control GO release. The developed hydrogels were characterized by chemical, physical, morphological, and cellular analyses. The results proved that the 3GO1 hydrogel is biocompatible and significantly enhanced the mechanical strength by encapsulating GO. Moreover, the rate of GO release depended on the crosslinking degree and environmental enzyme levels. Enzymatically released GO displayed uniform dispersity, retained its antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa through sharp edges and wrapping mechanisms, and promoted human fibroblast migration. This multifunctional hydrogel we developed with antibacterial efficacy is suitable for future application as wound dressings.

A novel alginate/gelatin sponge combined with curcumin-loaded electrospun fibers for postoperative rapid hemostasis and prevention of tumor recurrence

Surgical resection of the tumor remains the preferred treatment for most solid tumors at an early stage, but surgical treatment often leads to massive bleeding and residual tumor cells. Therefore, a novel alginate/gelatin sponge combined with curcumin-loaded electrospun fibers (CFAGS) for rapid hemostasis and prevention of tumor recurrence was prepared by using an electrospinning and interpenetrating polymer network (IPN) strategy. The present results show that alginate/gelatin sponge display excellent hemostatic properties and possess more advantages than commercial gelatin hemostasis sponge. More importantly, CFAGS could control the release of curcumin, inducing curcumin to accumulate at the surgical site of the tumor, thereby inhibiting local tumor recurrence in the subcutaneous postoperative recurrence model. In addition, the sponge was safe to implant in the body and did not cause toxicity to normal tissues and organs. This approach represents a new strategy to implant a dual functional sponge at the postoperative site as an adjuvant to the surgical treatment of cancer.

Tourniquets as a haemorrhage control measure in military and civilian care settings: An integrative review

AIMS AND OBJECTIVES

The aim of review was to describe and synthesise the evidence on the use of tourniquets to control haemorrhages, summarising both civilian and military use.

BACKGROUND

Trauma-related haemorrhage constitutes one of the most preventable deaths among injured patients, particularly in multi-casualty incidents and disasters. In this context, safe instruments such as tourniquets are essential to help healthcare professionals to minimise loss of life and maximise patient recovery.

DESIGN AND METHODS

An integrative review was conducted in Medline, Nursing & Allied Health Premium, and Health & Medical Collection, using published data until March 2021 and following the PRISMA guidelines.

RESULTS

A total of 25 articles were included. Evidence has been synthesised to understand the use of different types of tourniquets, environment of application, indication for their placement and potential complications associated with tourniquet placement.

CONCLUSIONS

Commercial tourniquets such as Combat Application Tourniquet or Emergency Tourniquet models are a valuable and safe instrument for haemorrhage control in both military and civilian out-of-hospital care settings. Nurses, as part of emergency teams, and other professionals should be aware that there is a possibility of adverse complications, but they are directly proportional to the time of tourniquet placement and generally temporary. In addition, national and international guidelines ensure the need for all civilian emergency services to be equipped with these devices, as well as for the training of healthcare professionals and first responders in their use.

RELEVANCE TO CLINICAL PRACTICE

Despite the lack of complications in the use of tourniquets in these cases, their use has been a matter of debate for decades. In this sense, this review yields up-to-date guidelines in the use of tourniquets, their recommendations and their significance among professionals to manage complicated situations.

Investigation of clinically acceptable agreement between two methods of automatic measurement of limb occlusion pressure: a randomised trial

Background

Development of automatic, pneumatic tourniquet technology and use of personalised tourniquet pressures has improved the safety and accuracy of surgical tourniquet systems. Personalisation of tourniquet pressure requires accurate measurement of limb occlusion pressure (LOP), which can be measured automatically through two different methods. The ‘embedded LOP’ method measures LOP using a dual-purpose tourniquet cuff acting as both patient sensor and pneumatic effector. The ‘distal LOP’ method measures LOP using a distal sensor applied to the patient’s finger or toe of the operating limb, using photoplethysmography to detect volumetric changes in peripheral blood circulation. The distal LOP method has been used clinically for many years; the embedded LOP method was developed recently with several advantages over the distal LOP method. While both methods have clinically acceptable accuracy in comparison to LOP measured using the manual Doppler ultrasound method, these two automatic methods have not been directly compared. The purpose of this study is to investigate if the embedded and distal methods of LOP measurement have clinically acceptable agreement. The differences in pairs of LOP measurement in the upper and lower limbs of 81 healthy individuals were compared using modified Bland and Altman analysis. In surgery, it is common for cuff pressure to deviate from the pressure setpoint due to limb manipulation. Surgical tourniquet systems utilise a ± 15 mmHg pressure alarm window, whereby if the cuff pressure deviates from the pressure setpoint by > 15 mmHg, an audiovisual alarm is triggered. Therefore, if the difference (bias) ± SE, 95% CI of the bias and SD of differences ± SE in LOP measurement between the embedded and distal methods were all within ±15 mmHg, this would demonstrate that the two methods have clinically acceptable agreement.

Results

LOP measurement using the embedded LOP method was − 0.81 ± 0.75 mmHg (bias ± standard error) lower than the distal LOP method. The 95% confidence interval of the bias was − 2.29 to 0.66 mmHg. The standard deviation of the differences ± standard error was 10.35 ± 0.49 mmHg. These results show that the embedded and distal methods of LOP measurement demonstrate clinically acceptable agreement.

Conclusions

The findings of this study demonstrate clinically acceptable agreement between the embedded and distal methods of LOP measurement. The findings support the use of the embedded LOP method of automatic LOP measurement using dual-purpose tourniquet cuffs to enable accurate, effective and simple prescription of personalised tourniquet cuff pressures in a clinical setting.

Intact parathyroid hormone levels localize causative glands in persistent or recurrent renal hyperparathyroidism: A retrospective cohort study

Persistent or recurrent renal hyperparathyroidism may occur after total parathyroidectomy and transcervical thymectomy with forearm autograft under continuous stimulation due to uremia. Parathyroid hormone (PTH) levels may reflect persistent or recurrent renal hyperparathyroidism because of the enlarged autografted parathyroid glands in the forearm or remnant parathyroid glands in the neck or mediastinum. Detailed imaging requires predictive localization of causative parathyroid glands. Casanova and simplified Casanova tests may be convenient. However, these methods require avascularization of the autografted forearm for >10 min with a tourniquet or Esmarch. The heavy pressure during avascularization can be incredibly painful and result in nerve damage. An easier method that minimizes the burden on patients in addition to predicting the localization of causative parathyroid glands was developed in this study. Ninety patients who underwent successful re-parathyroidectomy for persistent or recurrent renal hyperparathyroidism after parathyroidectomy between January 2000 and July 2019 were classified according to the localization of causative parathyroid glands (63 and 27 patients in the autografted forearm and the neck or mediastinum groups, respectively). Preoperatively, intact PTH levels were measured from bilateral forearm blood samples following a 5-min avascularization of the autografted forearm. Cutoff values of the intact PTH ratio (intact PTH level obtained from the non-autografted forearm before re-parathyroidectomy/intact PTH level obtained from the autografted forearm before re-parathyroidectomy) were investigated with receiver operating characteristic curves to localize the causative parathyroid glands. Intact PTH ratios of <0.310 with an area under the curve (AUC) of 0.913 (95% confidence interval [CI]: 0.856–0.970; P < 0.001) and >0.859 with an AUC 0.744 (95% CI: 0.587–0.901; P = 0.013) could predict causative parathyroid glands in the autografted forearm and the neck or mediastinum with diagnostic accuracies of 81.1% and 83.3%, respectively. Therefore, we propose that the intact PTH ratio is useful for predicting the localization of causative parathyroid glands for re-parathyroidectomy.