Saline Loading Research Articles

Abstract 05: Renal Resident Tissue Macrophages Contribute to Salt-Dependent Increases in IL-6

Salt-Sensitive hypertension is associated with an increase in pro-inflammatory cytokines and immune cells. We previously showed an acute increase in systolic blood pressure following IL-6 + high salt (HS) after 3 days, coupled with an immediate (1 day) reduction in sodium excretion. Renal resident tissue macrophages (rRTMs) form an intricate network within the kidney and function to both maintain homeostasis and secrete pro-inflammatory cytokines. We hypothesize that rRTMs are primary contributors to the immediate increases in IL-6 following high salt. To test this hypothesis, male wild-type mice lacking a functional CX 3 CR 1 chemokine receptor (CX 3 CR 1 - EGFP+/+ ) or wild-type (Wt, C57Bl6) were used. CX 3 CR 1 is required for RTM localization to the kidney; thus, these mice are rRTM-depleted. Mice were fed HS (1% saline or 4% HS chow) or normal chow (NC) for 6 days and kidneys harvested. Kidneys were digested and FACS analysis performed on total immune cell populations or used for RT-PCR (n=4-5 Wt & rRTM-depleted). Cells were gated on: Live + CD45 + + MHCII + Lyc6C - + B220 - + CD64 + + F4/F80 hi + CD11b lo. Or Lyc6C hi . Lyc6C hi and rRTMs were pre-stimulated (LPS, 1mg/mL, 3hrs) before staining with intracellular IL-6 antibody. FACS data were analyzed as a percent increase (mean fluorescence intensity, MFI) of IL-6 over control. RT-PCR data were analyzed as DCt/housekeeping. Our data show that rRTMs are the most abundant immune cell in the kidney (23.4% of total CD45 + ) and predominantly reside in the cortex and outer medulla (>99%). HS feeding (4%) significantly increased whole kidney IL-6 mRNA (12.0 ± 0.5 vs . 15.3 ± 0.6 DCt Wt NC, **p<0.01). This increase was completely prevented in rRTM-depleted mice. While intracellular IL-6 levels were generally increased in LPS-stimulated Lyc6C hi inflammatory monocytes, the rRTMs showed a preferential increase in intracellular IL-6 with both hyperosmolar saline (1%, >13% increase) and HS chow (4%, >50%). Here, we show that rRTM-depletion prevents the HS-induced increase in kidney IL-6. We additionally show that rRTMs are preferentially increasing intracellular levels of IL-6 following an acute HS load of hyperosmolar saline (1%) or HS chow (4%). We previously demonstrated that IL-6 contributes to increased blood pressure and sodium retention, and these data suggest that rRTMs preferentially contribute to the increased IL-6.

Detection of Traumatic Ankle Arthrotomies: Computed Tomography Scan Versus Saline Load Test.

Periarticular wounds present a common diagnostic dilemma for emergency providers and orthopedic surgeons because traumatic arthrotomies (TA) often necessitate different management from superficial soft tissue wounds. Historically, TA have been diagnosed with the saline load test (SLT). Computed tomography (CT) scan has been studied as an alternative to SLT in diagnosing TA in several joints, but there are limited data specifically pertaining to the ankle. This study aimed to compare the ability of a CT scan to identify an ankle TA versus a traditional SLT. The hypothesis was that there would be no significant difference between a CT scan and SLT in diagnosing ankle TA in a cadaveric model. This cadaveric study used 10 thawed fresh-frozen cadaveric ankles. A baseline CT scan was performed to ensure no intra-articular air existed before simulated TA. After the baseline CT, a 1 cm TA was created in the anterolateral arthroscopy portal site location. The ankles then underwent a postarthrotomy CT scan to evaluate for the presence of intra-articular air. After the CT scan, a 30 mL SLT was performed using the anteromedial portal site location. After arthrotomy, intra-articular air was visualized in 7 of 10 cadavers in the postarthrotomy CT scan. All the ankles had fluid extravasation during the SLT with <10 mL of saline. The sensitivity of the SLT for TA was 100% versus 70% for the CT scan. The SLT was more sensitive in diagnosing 1-cm ankle TA than a CT scan in a cadaveric model.

Computed Tomography Scan Versus Saline Load Test in the Detection of Traumatic Arthrotomies of the Ankle: A Cadaveric Study.

To evaluate the sensitivity and ability of computed tomography (CT) scan for diagnosing traumatic ankle arthrotomies compared with that of the saline load test (SLT). Eleven cadaveric ankles were included in this study. Before intervention, a CT scan was obtained to confirm the absence of intra-articular air. Arthrotomies were created at the anterolateral, posterolateral, anteromedial, and posteromedial aspects of the ankle under fluoroscopic visualization. A postarthrotomy and postrange of motion CT scan was obtained to evaluate for the presence of intra-articular air. Each ankle then underwent a SLT with 60 mL of saline, where volumes provoking extravasation were recorded. Of the 11 included ankles, intra-articular air was detected in all 11 ankles by CT scan. All 11 ankles also demonstrated extravasation of saline through the arthrotomy site during SLT. Thus, the sensitivity for both CT scan and SLT for detecting ankle traumatic arthrotomy was 100%. The mean volume of saline needed for extravasation was 7.7 mL, with a range of 3-22 mL and a SD of 5.4. Given that CT scan was equally as sensitive to the SLT, this study presents good evidence that CT scan may be used for the detection of ankle traumatic arthrotomies.

Commentary on: "Computed Tomography Scan Versus Saline Load Test in the Detection of Traumatic Arthrotomies of the Ankle: A Cadaveric Study" and "Detection of Traumatic Ankle Arthrotomies: Computed Tomography Scan Versus Saline Load Test".

Commentary on: "Computed Tomography Scan Versus Saline Load Test in the Detection of Traumatic Arthrotomies of the Ankle: A Cadaveric Study" and "Detection of Traumatic Ankle Arthrotomies: Computed Tomography Scan Versus Saline Load Test".

Using Point-of-care Ultrasonography to Diagnose Traumatic Arthrotomy of the Knee: A Case Series.

Accurate diagnosis of traumatic arthrotomy of the knee (TAK) is critical for patients presenting to the emergency department (ED) to ensure timely treatment. Current diagnostic modalities including plain radiography, computed tomography (CT), and the saline load test (SLT) have advantages and disadvantages. Point-of-care-ultrasonography (POCUS) offers a possible timely, low-cost, and efficient alternative method of diagnosing TAK. In this case series we present three cases where POCUS was used to diagnose TAK in the ED. Three patients in their early 20s presented to the ED complaining of knee trauma with wounds in proximity to the joint. Mechanisms of injury included a gunshot wound in one case and blunt trauma (motor vehicle collision and bicycle crash) in two cases. In all three cases TAK was suggested on POCUS examinations by the presence of intra-articular hyperechoic foci consistent with air artifact. All three cases had TAK confirmed by orthopedic evaluation. Ultrasound may have utility in the evaluation of patients presenting with knee trauma where TAK is a concern. The SLT is generally considered the gold standard test for diagnosis of TAK, but it is invasive and has a wide range of diagnostic accuracy. Intra-articular air has been found to be a sensitive marker for TAK in CT studies. Thus, additional investigations into the diagnostic accuracy of POCUS for this finding should be undertaken.

Right Heart Reserve Function Assessed With Fluid Loading Predicts Late Right Heart Failure After Left Ventricular Assist Device Implantation

BackgroundA left ventricular assist device (LVAD) is an effective therapeutic option for advanced heart failure. Late right heart failure (LRHF) is a complication after LVAD implantation that is associated with increasing morbidity and mortality; however, the assessment of right heart function, including right heart reserve function after LVAD implantation, has not been established. We focused on a fluid-loading test with right heart catheterization to evaluate right heart preload reserve function and investigate its impact on LRHF. MethodsPatients aged > 18 years who received a continuous-flow LVAD between November 2007 and December 2022 at our institution, and underwent right heart catheterization with saline loading (10 mL/kg for 15 minutes) 1 month after LVAD implantation, were included. ResultsOverall, 31 cases of LRHF or death (right heart failure [RHF] group) occurred in 149 patients. In the RHF vs the non-RHF groups, the pulmonary artery pulsatility index (PAPi) at rest (1.8 ± 0.89 vs 2.5 ± 1.4, P = 0.02) and the right ventricular stroke work index (RVSWi) change ratio with saline loading (0.96 ± 0.32 vs 1.1 ± 0.20, P = 0.03) were significantly different. The PAPi at rest and the RVSWi change ratio with saline loading were identified as postoperative risks for LRHF and death. The cohort was divided into 3 groups based on whether the PAPi at rest and the RVSWi change ratio were low. The event-free curve differed significantly among the 3 groups (P < 0.001). ConclusionsHemodynamic assessment with saline loading can evaluate the right ventricular preload reserve function of patients with an LVAD. A low RVSWi change with saline loading was a risk factor for LRHF following LVAD implantation.

Safety of ventricular arrhythmia radiofrequency ablation with half-normal saline irrigation.

Failure of radiofrequency (RF) ablation of ventricular arrhythmias is often due to inadequate lesion size. Irrigated RF ablation with half-normal saline (HNS) has the potential to increase lesion size and reduce sodium delivery to the patient if the same volume of RF irrigant were used for normal saline (NS) and HNS but could increase risks related to steam pops and lesion size. This study aims to assess periprocedural complications and acute ablation outcome of ventricular arrhythmias ablation with HNS. Prospective assessment of outcomes was performed in 1024 endocardial and/or epicardial RF ablation procedures in 935 consecutive patients (median age 64 years, 71.2% men, 73.4% cardiomyopathy, 47.2% sustained ventricular tachycardia). Half-normal saline was selected at the discretion of the treating physician. Radiofrequency ablation power was generally titrated to a ≤15 Ω impedance fall with intracardiac echocardiography monitoring. Half-normal saline was used in 900 (87.9%) and NS in 124 (12.1%) procedures. Any adverse event within 30 days occurred in 13.0% of patients treated with HNS RF ablation including 4 (0.4%) strokes/transient ischaemic attacks and 34 (3.8%) pericardial effusions requiring treatment (mostly related to epicardial access). Two steam pops with perforation required surgical repair (0.2%). Patients who received NS irrigation had less severe disease and arrhythmias. In multivariable models, adverse events and acute success of the procedure were not related to the type of irrigation. Half-normal saline irrigation RF ablation with power guided by impedance fall and intracardiac echocardiography has an acceptable rate of complications and acute ablation success while administering half of the saline load expected for NS irrigation.

Kiosk 6R-FB-01 - Ventricular Extracellular Volume and Mass Changing Induced by Acute Saline Loading

Kiosk 6R-FB-01 - Ventricular Extracellular Volume and Mass Changing Induced by Acute Saline Loading

Correlation of Histopathologic Subtypes of Primary Aldosteronism with Clinical Phenotypes and Postsurgical Outcomes.

Clinical implications of unilateral primary aldosteronism (PA) histopathology remain to be determined in various ethnic populations. We examined the histopathology of unilateral PA using CYP11B2 immunostaining in relation to clinical phenotypes and postsurgical outcomes. Patients consecutively operated for unilateral PA from 2010 to 2020 at 3 tertiary hospitals in South Korea were retrospectively enrolled. Adrenals with solitary aldosterone-producing adenomas and/or dominant aldosterone-producing nodules were classified as the classical and the others as the nonclassical groups. The classical group was subdivided into mixed or solitary group according to whether other aldosterone-producing lesions coexist or not. Of the 240 cases, 124 were solitary, 86 mixed, and 30 nonclassical. Baseline serum potassium concentration was lower in the solitary group than the mixed or nonclassical group. Plasma aldosterone concentration after saline loading was the highest in the solitary group (median 31.65 ng/dL), followed by the mixed group (median 25.40 ng/dL), and the lowest in the nonclassical group (median 14.20 ng/dL). Solitary and mixed groups showed higher lateralization indices and lower contralateral indices than the nonclassical group. The contralateral index was lower in the solitary group than the mixed group. At 6 to 12 months after adrenalectomy, fewer antihypertensive medications were required for the solitary and mixed groups than the nonclassical group. The solitary group, followed by the mixed group, was associated with more severe hyperaldosteronism and more suppressed aldosterone production from the contralateral side than the nonclassical group. Histopathologic phenotypes were related to the clinical manifestations and may suggest postoperative prognosis.

FRI130 Usefulness Of The Upright Posture Test In The Diagnosis Of Primary Aldosteronism

Abstract Disclosure: N. Younes: None. M. St-Jean: None. M. Desrochers: None. I. Bourdeau: None. A. Lacroix: None. Objectives: Renin-independent aldosterone excess characterizes primary aldosteronism (PA). We have previously shown that PA is frequently regulated by aberrant stimuli, including the upright posture stimulation test (UPT), in which plasma aldosterone concentrations (PAC) increase in a renin-independent manner. In this study, we further examined the usefulness of UPT in diagnosing PA. Methods: We conducted a retrospective analysis of the medical records of 187 adult patients who underwent an UPT as part of their evaluation for possible PA and 25 control subjects, in 2 referral university centers between January 2011 and December 2021. UPT was conducted in an ambulatory setting, mostly in patients with potential false negative or borderline results of oral/IV saline confirmation tests. UPT was performed in a fasting state, early morning, 72 hours off beta-blockers, ACE, or ARBS. Patients were in a supine posture for 1 hour, followed by ambulation for 2 hours. Blood samples were collected for PAC, renin, and cortisol, at baseline and at 30 minutes intervals during ambulation. An abnormal response was defined as a ≥50% rise in PAC with a suppressed renin (≤10.1 ng/L or ≤1 ng/mL/h) and a cortisol increase ≤50%. Results: Median age of patients was 55.0 [IQR (46.0; 63.0)], 52.4% were female. 93.6% were taking at least one antihypertensive medication and 32% had hypokalemia. 43.5% did not have adrenal nodules at imaging. 76.5% (n=143) were diagnosed with PA, based on either IV/oral sodium load or UPT. When compared to controls, PA patients had higher basal PAC and lower basal renin levels (p&amp;lt;.0001) and achieved a higher maximal PAC and lower maximal renin (renin max) in response to posture [median PAC (IQR): 802.0 pmol/L (569.0, 1244.0) in PA v/s 624.0 pmol/L (500.0, 736.0) in controls, p=0.0081 and median renin 5.0 ng/L [IQR (3.0, 8.0)] in PA v/s 27.5 ng/L in controls (19.0, 46.0); p&amp;lt;.0001]. Renin max ≤10.1 had the best sensitivity and specificity for predicting PA (90% and 92%, respectively). 95.3% of PA patients increased PAC by at least 50% on UPT (median increase 363%), while renin remained suppressed. All 42 PA patients with a false negative (PAC ≤162 pmol/L) on IV saline test had a renin max ≤10.1 during UPT and 97.6% increased aldosterone by at least 50%. 84% of PA patients with a borderline response (162-240 pmol/L) on IV saline test, had a renin max ≤10.1 and all patients increased aldosterone by at least 50%. 42 patients underwent adrenal vein sampling: 50% had lateralized PA (potassium was lower than in bilateral PA, p=0.003). However, the aldosterone and renin response to UPT did not significantly differ between the two subtypes of PA. Conclusion: A renin-independent aldosterone increase during UPT can be used to confirm PA diagnosis, which was particularly useful in patients with false negative saline loading tests. Renin-independent PAC response to UPT occurred equally in lateralized and bilateral PA. Presentation: Friday, June 16, 2023

The role of computed tomography in the detection of traumatic arthrotomies of the elbow: a cadaveric study

Abstract Purpose: To evaluate the use of computed tomography (CT) imaging as a diagnostic tool for elbow arthrotomies using a standardized cadaveric arthrotomy model. Method: Nineteen intact fresh frozen cadaver elbows were CT scanned using 2 mm cuts with sagittal and coronal reformats in the plane of the joint and used as controls. An elbow arthrotomy at the posterocentral arthroscopic portal site was performed in all specimens using a 4.5 millimeter trocar. After arthrotomy, all elbows underwent a second CT scan followed by a standard saline load test (SLT). Images were randomized and reviewed by 2 blinded, independent reviewers. Bimodal scoring was performed for each specimen with regard to the presence of an arthrotomy indicated by presence of air in the joint. Regarding the SLT, saline exiting the arthrotomy wound was considered a positive test. Results: CT scans were found to have 100% sensitivity and 86% specificity for diagnosing elbow arthrotomies. Interrater reliability calculated with Cohen kappa statistic was near perfect at r = 0.89. The SLT had a sensitivity of 79% when 20 mL was injected. A total of 25 mL of saline was required to be injected for a sensitivity greater than 95%. Conclusion: This study demonstrates that CT scan is a reliable and less technically demanding method of diagnosis arthrotomies with high interrater reliability and high sensitivity and with results comparable with SLT. This technique may be useful in centers where trained providers are not readily available to perform SLT. Clinical study is required to validate our results. Level of Evidence: Level II.

Abstract 128: Saline Load Induces Acute Changes In Ventricular Extracellular Volume And Mass

Background: Maladaptive left ventricular hypertrophy (LVH) in hypertension is generally regarded as a result of myocardial fibrosis. However, salt loading induces a systemic and isotonic expansion of the extracellular (EC) volume in tissues, which could affect myocardial structure independent of fibrosis. Methods: Cardiac MRI, including cine-images and native T1 and T2 mapping as surrogates for EC volume and myocardial water content, was performed immediately before and after a saline infusion test (SIT; 2L NaCL 0.9% in 4h) in patients with primary aldosteronism (PA), a prototypic sodium-retentive form of hypertension. Results: We enrolled 13 consecutive patients with PA (5F; 50±12 yo; BP=140/88±14/7 mmHg; sK + =3.7±0.4 mmol/L on KCl supplements; renin=2.5[2.0-4.8] mIU/L, aldosterone=568[368-737] pmol/L), lacking aldosterone suppression after SIT (562 [262-776] pmol/L, p=0.127). SIT induced a small but significant increase in wall thickness (septum: 9.0±1.5 vs 9.5±1.0 mm, p=0.027) and, overall, in left ventricular mass (56.3±9.1 vs 58.0±9.2 g/m 2 , p=0.026), paralleled by an increase in myocardial T1 (1012±29 vs 1027±25 ms, p&lt;0.001) and T2 (49.9±2.0 vs 51.2±2.7 ms, p=0.012). After saline the left ventricular ejection fraction was mildly reduced (56[55-62] vs 53[51-59]%, p=0.023), reflecting an increase in end-systolic (ES) volume (38±10 vs 43±10 ml/m 2 , p=0.030) without significant changes in the end-diastolic (ED) volume (88±18 vs 91±16 ml/m 2 , p=0.114). Conclusions: Within a timeframe inconsistent with EC matrix remodeling, saline load induced an increase in ventricular mass and an expansion of the EC volume, i.e. edema, in a human model of salt-related disease.

CT scan versus Saline Load Test for Detection of Traumatic Shoulder Arthrotomy: A Cadaveric Study.

Traumatic shoulder arthrotomy (TSA) is a rare injury that is commonly detected through saline load test (SLT). There are no studies that have studied the ability of CT scan to detect a TSA. The purpose of this study is to determine the ability of CT scan to detect a TSA and compare it to the SLT. Twelve cadaveric shoulders were included in the study. Before intervention, a CT scan was conducted to determine presence of intra-articular air. After confirmation that no air was present, an arthrotomy was made at the anterior or posterior portal site. A CT was obtained post-arthrotomy to evaluate for intra-articular air. Each shoulder then underwent a SLT to assess the sensitivity of SLT and the volume needed for extravasation. Twelve shoulders were included after pre-intervention CT scan. Six shoulders received an arthrotomy through the anterior portal and six shoulders received an arthrotomy through the posterior portal. After the arthrotomy, air was visualized on CT scan in eleven of the twelve shoulders (92%). All twelve shoulders demonstrated extravasation during SLT. The mean volume of saline needed for extravasation was 29 ml with a standard deviation of 10 and range of 18 to 50ml. CT scan is a sensitive modality (sensitivity of 92%) for detection of TSA. In comparison, SLT is more sensitive (sensitivity of 100%) and outperforms CT scan for the diagnosis of TSA in a cadaveric model. Further research is needed to solidify the role that CT imaging has in the diagnosis of TSAs.

Brief early life angiotensin-converting enzyme inhibition attenuates the diuretic response to saline loading in sheep with solitary functioning kidney.

A solitary functioning kidney (SFK) from birth predisposes to hypertension and kidney dysfunction, and this may be associated with impaired fluid and sodium homeostasis. Brief and early angiotensin converting enzyme inhibition (ACEi) in a sheep model of SFK delays onset of kidney dysfunction. We hypothesized that modulation of the renin angiotensin system via brief postnatal ACEi in SFK would reprogram renal sodium and water handling. Here, blood pressure (BP), kidney haemodynamics and kidney excretory function were examined in response to an isotonic saline load (0.13 ml/kg/min; 180 minutes) at 20 months of age in SFK (fetal unilateral nephrectomy at 100 days gestation; term 150 days), sham and SFK+ACEi sheep (ACEi in SFK 4-8 weeks of age). Basal BP was higher in SFK than sham ( 13 mm Hg), and similar between SFK and SFK+ACEi groups. Saline loading caused a small increase in BP ( 3-4 mm Hg) the first two hours in SFK and sham sheep but not SFK+ACEi sheep. Glomerular filtration rate did not change in response to saline loading. Total sodium excretion was similar between groups. Total urine excretion was similar between SFK and sham animals but was 40% less in SFK+ACEi animals compared to SFK animals. In conclusion, this study indicates that water homeostasis in response to a physiological challenge is attenuated at 20 months of age by brief early life ACEi in SFK. Further studies are required to determine if ACEi in early life in children with SFK could compromise fluid homeostasis later in life.

Radiographic Measurements Correlate to Isolated Posterolateral Corner (PLC) Injury in a Novel Cadaveric Model.

Injury to the posterolateral corner (PLC) of the knee often requires surgical reconstruction. There remains no consensus on treatment for PLC injury, and, therefore, it is imperative to have a reproducible injury model to improve the general knowledge of PLC injuries. A novel cadaveric model of isolated PLC injury is proposed and evaluated using radiographic parameters as well as gross dissection. All protocols were reviewed by the Human Investigation and Research Committee of the home institution and were approved. Translational force in a defined posterior and lateral direction was applied to cadaveric native knees to induce PLC injury. Varus and recurvatum stress fluoroscopic imaging was obtained of each specimen before and after the injury model. Lateral joint distance and recurvatum angle after stress was measured on each image via picture archiving and communication software (PACS) imaging software. After the injury model, injured structures were assessed via saline loading and gross dissection. Any specimens found to be fractured were excluded from the analysis of stress radiography. A total of 12 knees underwent testing and 6/12 successfully induced PLC injury without fracture. The lateral capsule was torn in every specimen. The popliteofibular ligament (PFL) was torn in 83% of specimens and the fibular collateral ligament (FCL) in 66.7% of specimens. The median lateral gapping after injury under varus stress radiography was 5.39 mm and the median recurvatum angle after injury was 14.25°. Radiographic parameters had a direct relationship with a number of structures injured. This is the first successful cadaver model of PLC injury. The lateral capsule was injured in every specimen emphasizing the importance of this structure to the PLC.

Safe and Effective Aspirations and Nerve Blocks for the On-Call Orthopaedic Surgeon.

The on-call orthopaedic surgeon is faced with a wide array of orthopaedic pathology for which intra-articular aspiration, injection, and/or nerve/hematoma block may be used. Efficient use of these diagnostic and therapeutic modalities affords better patient care and a more effective on-call period. Often, these interventions are the rate limiting factor in a reduction or diagnosis. In this review, we describe joint aspirations, saline load tests, hematoma blocks, and nerve blocks in detail to include their indications, techniques, related pharmacology, pearls, and pitfalls.

Computed Tomography Provides Effective Detection of Traumatic Arthrotomy of the Elbow.

Failure to identify a traumatic arthrotomy of the elbow (TAE) can lead to septic arthritis with devastating complications. The gold standard for TAE detection remains controversial, and evidence is limited. While multiple clinical and cadaveric studies have validated the use of computed tomography (CT) to detect traumatic arthrotomies about the knee, other studies have called into question whether the use of CT to detect traumatic arthrotomy is applicable to the elbow. A prior cadaveric study utilizing a direct posterior (transtendon) traumatic arthrotomy model failed to detect traumatic arthrotomy via CT in 100% of cases11. The aim of this study was to determine the sensitivity and specificity for detecting TAE with CT, utilizing a lateral traumatic arthrotomy model. Ten fresh-frozen upper extremity transhumeral cadaveric specimens were utilized. Only specimens with an intact elbow joint and no known elbow surgery or injury were included. CT scans were performed to screen for intra-articular air prior to arthrotomy. A full thickness 10 mm incision was performed over the soft spot, just distal to the lateral epicondyle. The elbow was taken through full range of motion in flexion and extension, as well as forearm pronation and supination 10 times. CT scans were then repeated and screened for the presence of intra-articular air. Lastly, a saline load test was performed on all specimens, and the volume of saline required to detect the arthrotomy was recorded. Of the 10 specimens, 0% (n=0) demonstrated intra-articular air of the elbow joint on CT scan prior to arthrotomy, and 100% (n=10) demonstrated intra-articular air on CT scan following arthrotomy. CT scan demonstrated 100% sensitivity and 100% specificity for TAE. For the saline load test, 90% (n=9) were positive for TAE at an average of 12 mL (range: 4mL-47mL), providing 90% sensitivity. In this cadaveric study utilizing a more commonly observed direct lateral traumatic laceration, CT was able to detect 100% (n=10) of TAEs with 100% sensitivity and specificity. These results show that CT scans can effectively diagnose lateral traumatic arthrotomy in a cadaveric model and can be a viable option for diagnosis in a clinical setting. Clinical correlation is required to confirm in these in vitro findings.

The “forgotten circulation”: Sympathetic control of mesenteric venous capacity in conscious hypertensive rats

The venous circulation is often “forgotten,” as cardiovascular research and therapeutic intervention focusses predominantly on arteries. However, systemic veins store two-thirds of blood volume at rest, with reservoir beds such as the mesenteric circulation receiving dense sympathetic innervation, suggesting a critical neurogenic role for the mobilization of blood. The impact of hypertension on sympathetic regulation of venous circulation remains unclear. We hypothesized that capacity of mesenteric vasculature is impaired in spontaneously hypertensive rats (SHR) and that reducing sympathetic drive will increase mesenteric buffering of excess volume.SHR (n=6) and Wistar rats (n=7) were instrumented with telemeters recording arterial and venous pressures, and an atrial balloon for assessment of mean circulatory filling pressure (MCFP). Arterial (inflow) and venous (outflow) mesenteric flow probes were implanted to measure total mesenteric volume fluctuation. Mesenteric vascular capacity was challenged with 20% volume load of intravenous saline. In SHR sympathetic drive was reduced via hexamethonium (10mg/kg) or via carotid body denervation (CBD).MCFP was elevated in SHR (+2.7±0.5mmHg, p&lt;0.01 vs Wistars). MCFP in SHR was reduced by hexamethonium (-2.6±0.6; p=0.01 vs Baseline, n=5) and CBD (‑2.0±0.7mmHg; p=0.04 vs Baseline, n=5). In normotensives volume load was accommodated by the mesenteric bed, with a net total influx of blood (+5.4±2.2ml; n=7). In contrast, SHR showed a counter-intuitive net efflux of blood from the mesenteric bed (-1.6±1.4ml; p=0.04 vs Wistars, n=6). Preliminary results indicate that hexamethonium and CBD tended to increase the ability of the mesenteric bed to accommodate volume (hexamethonium: +1.9±1.5, n=6; CBD: +0.8±0.6ml, n=3).We show that SHR have higher venous tone and reduced capacity to accommodate excess volume within the mesenteric vascular bed. Reductions in sympathetic drive reduced venous tone and improved the ability to accommodate volume load. Inhibiting sympathetic activity may provide a novel therapeutic opportunity to restore venous mesenteric capacity and potentially ameliorate hypertension. Marsden Fund, Royal Society of New Zealand; Health Research Council of New Zealand This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Association between salt sensitivity of blood pressure and the risk of hypertension in a Chinese Tibetan population.

Epidemiological studies have confirmed salt sensitivity as a crucial risk factor for the development of hypertension. However, few studies have investigated the association between salt sensitivity of blood pressure (SSBP) and hypertension in Chinese Tibetan population. Therefore, we conducted a cross-sectional study based on a Tibetan population to evaluate the association between SSBP and the risk of hypertension. Seven hundred and eighty-four participants with hypertension and 645 participants without hypertension were included from five villages in Tibetan Autonomous Region of Gannan during 2013-2014. The assessment of salt sensitivity (SS) and non-salt sensitivity (NSS) was performed according to mean arterial pressure (MAP) changes by the modified Sullivan's acute oral saline load and diuresis shrinkage test (MSAOSL-DST). Logistic regression models and restricted cubic models were used to examine the association between SSBP and hypertension. There were 554 (70.5%) salt-sensitive participants with hypertension and 412 (63.9%) salt-sensitive participants without hypertension in this study. Compared with individuals with NSS, individuals with SS had a significantly increased risk of hypertension, and the multiple-adjusted odds ratios were 2.582 with 95% confidence interval of 1.357-4.912. Furthermore, a significant linear trend was found between MAP changes and hypertension. Subgroup analyses showed significant and stronger associations between SSBP and the risk of hypertension in the older (age≥55years old), males and participants who took exercise less than 1 time per week. Our results suggest that SS is associated with an increased risk of hypertension in Tibetan population, indicating a need for clinicians dealing with SSBP to decrease the risk of hypertension.

Groundwater Hydrochemical Characteristics and Water Quality in Egypt’s Central Eastern Desert

The rapid expansion of economic activities in Egypt’s Central Eastern Desert has resulted in poorly coordinated groundwater development, having a negative impact on the resource. This study was conducted to assess the hydrochemical characteristics of the different aquifers in the Central Eastern Desert, with an emphasis on the impact of seawater intrusion and groundwater quality for different purposes. A total of 21 groundwater samples were collected representing the three main aquifers (Eocene Carbonate, Nubian Sandstone, and Fractured Basement) in the Central Eastern Desert, and analyzed for major ions and trace elements. The majority of the samples had electrical conductivity values that exceeded the salinity limit for natural water. Groundwater saline load is primarily influenced by sodium, calcium, chloride, and sulfate concentrations. The groundwater in the Central Eastern Desert mainly consists of Na-Cl, Ca-Cl, and Na-SO4 water-types. Saltwater intrusion and water-rock interactions via cation exchange and minerals weathering are the primary controlling factors of groundwater hydrochemistry. The high salinity of this groundwater renders it unsuitable for irrigation or consumption. Additionally, it is unfit for domestic use based on total hardness values. Furthermore, the Al, Cd, Fe, Mn, and Ni concentrations in the investigated groundwater exceed the allowable limits for human consumption. Proper mitigation measures and adaptation strategies are required for groundwater sustainability in the Central Eastern Desert.