Water Conservation Overrides Osmotic Diuresis During SGLT2 Inhibition in Patients With Heart Failure.

BACKGROUND: Sodium-glucose cotransporter 2 inhibitors are believed to improve cardiac outcomes due to their osmotic diuretic potential. OBJECTIVES: The goal of this study was to test the hypothesis that vasopressin-driven urine concentration overrides the osmotic diuretic effect of glucosuria induced by dapagliflozin treatment. METHODS: DAPA-Shuttle1 (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment) was a single-center, double-blind, randomized, placebo-controlled trial, in which patients with chronic heart failure NYHA functional classes I/II and reduced ejection fraction were randomly assigned to receive dapagliflozin 10 mg daily or placebo (1:1) for 4 weeks. The primary endpoint was change from baseline in urine osmolyte concentration. Secondary endpoints included changes in copeptin levels and solute free water clearance. RESULTS: Thirty-three randomized, sodium-glucose cotransporter 2 inhibitor-naïve participants completed the study, 29 of whom (placebo: n = 14; dapagliflozin: n = 15) provided accurate 24-hour urine collections (mean age 59 ± 14 years; left ventricular ejection fraction 31% ± 9%). Dapagliflozin treatment led to an isolated increase in urine glucose excretion by 3.3 mmol/kg/d (95% CI: 2.51-4.04; P < 0.0001) within 48 hours (early) which persisted after 4 weeks (late; 2.7 mmol/kg/d [95% CI: 1.98-3.51]; P < 0.0001). Dapagliflozin treatment increased serum copeptin early (5.5 pmol/L [95% CI: 0.45-10.5]; P < 0.05) and late (7.8 pmol/L [95% CI: 2.77-12.81]; P < 0.01), leading to proportional reductions in free water clearance (early: -9.1 mL/kg/d [95% CI: -14 to -4.12; P < 0.001]; late: -11.0 mL/kg/d [95% CI: -15.94 to -6.07; P < 0.0001]) and elevated urine concentrations (late: 134 mmol/L [95% CI: 39.28-229.12]; P < 0.01). Therefore, urine volume did not significantly increase with dapagliflozin (mean difference early: 2.8 mL/kg/d [95% CI: -1.97 to 7.48; P = 0.25]; mean difference late: 0.9 mL/kg/d [95% CI: -3.83 to 5.62]; P = 0.70). CONCLUSIONS: Physiological-adaptive water conservation eliminated the expected osmotic diuretic potential of dapagliflozin and thereby prevented a glucose-driven increase in urine volume of approximately 10 mL/kg/d · 75 kg = 750 mL/kg/d. (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment [DAPA-Shuttle1]; NCT04080518).

Effect of mannitol on acute kidney injury induced by cisplatin.

PURPOSE: Acute kidney injury (AKI) is a frequent dose-limiting toxicity induced by cisplatin. Mannitol has been used in hydration protocols to mitigate this adverse event but its role remains controversial. The aim of this study is to define the impact of mannitol on AKI in patients receiving cisplatin. METHODS: This retrospective observational study was conducted in cancer patients who received at least one dose of cisplatin between September 2010 and December 2016 at the Centre hospitalier de l'Université de Montréal. The primary outcome of this study was the comparison of all grade cisplatin-associated AKI between hydration protocols with or without mannitol. RESULTS: A total of 1821 patients were included of which 658 received mannitol whilst 1163 received hydration alone. The risk of all grade cisplatin-associated AKI was significantly lower for the mannitol group (Hazard Ratio (HR) = 0.62; 95% CI [0.42, 0.89]). This result was mainly driven by gynecologic (HR = 0.50), upper gastrointestinal (HR = 0.32), urinary tract malignancies (HR = 0.29) and lymphoma (HR = 0.33). No significant difference was seen for head and neck (HN), lung, germ cells and other cancers. However, HN cancers patients receiving mannitol had fewer grade 2 and 3 AKI. Significantly fewer AKI events were observed in HN, lung, upper gastrointestinal and urinary tract cancer when mannitol was added for cisplatin dose <75 mg/m2. CONCLUSION: Although the results were generally driven by a decrease of grade 1 AKI for most cancers, the greatest benefit of mannitol was seen with cisplatin doses lower than 75 mg/m2 and should probably be reinstated in this setting.

Mannitol Improves Intraoperative Brain Relaxation in Patients With a Midline Shift Undergoing Supratentorial Tumor Surgery: A Randomized Controlled Trial.

BACKGROUND: Mannitol is widely used to reduce brain tissue swelling and improve brain relaxation during neurosurgery. However, the optimal dosage for patients with midline shift undergoing supratentorial tumor resection remains unclear. METHODS: In this randomized, controlled double-blinded study, 204 patients with preoperative midline shift who underwent elective supratentorial brain tumor surgery were equally allocated to receive placebo or 0.7, 1.0, or 1.4 g/kg mannitol infusion. The primary outcome was the proportion of satisfactory brain relaxation. RESULTS: Demographics and baseline characteristics were similar among the 4 groups. Trend analysis showed that mannitol infusion increased satisfactory brain relaxation (P<0.0001), relaxed dural tension (P<0.0001) and adequate surgical exposure (P<0.0001), and decreased the requirement for rescue therapy for brain swelling (P<0.0005), all in a dose-dependent manner. Tumor size (odds ratio [OR]: 0.99 per 1 mm, 95% confidence interval [CI]: 0.989-0.998, P=0.004), peritumoral edema classification (OR: 0.60, 95% CI: 0.37-0.97; P=0.038) as well as mannitol dose (OR: 2.81, 95% CI: 1.97-4.02, P<0.0001) were significantly associated with satisfactory brain relaxation. An increased risk of moderate to severe postoperative cerebral edema was found in the group receiving 1.4 g/kg mannitol (P=0.025) in a dose-dependent manner (P=0.018). CONCLUSIONS: An optimal mannitol infusion dosage of 1.0 g/kg is recommended to improve brain relaxation with lower risk of moderate to severe postoperative cerebral edema in patients with midline shift undergoing supratentorial tumor resections. The effect of mannitol on brain relaxation is affected by tumor size and severity of peritumoral edema, rather than by midline shift.

Examining Mannitol Use in Kidney Cancer Surgery: A Cautionary Tale of Extrapolated Surgical Data.

Mannitol for renal protection during partial nephrectomy is common but unsupported by evidence from clinical trials. The impact of mannitol on renal physiology includes both beneficial and harmful effects. Current understanding of renal ischemia reperfusion injury suggests potentially targetable processes that have a lower potential risk.

Phase III Trial of Intravenous Mannitol Versus Placebo During Nephron-sparing Surgery: Post Hoc Analysis of 3-yr Outcomes.

Our recently reported phase III trial demonstrated that patients undergoing nephron-sparing surgery (NSS) with an estimated glomerular filtration rate (eGFR) of ≥45 ml/min/1.73 m2 who received mannitol had no improvement in renal function at 6 mo compared with those who received placebo. Some authors have suggested that benefit is restricted to subgroups, such as those with comorbidities. We assessed whether preoperative eGFR, or other patient and surgical factors modified the effect of mannitol on postoperative outcomes at 6 mo and with extended follow-up. We also assessed whether mannitol was associated with differences in long-term GFR years after surgery. No significant difference between the mannitol or placebo groups (mean eGFR difference: 1.4; 95% confidence interval: -2.6, 5.3; p = 0.5) was found in the 134 patients with known eGFR at 3 yr after NSS. At both 6 mo and 3 yr, the effect of mannitol was not significantly modified by patient or surgical factors including preoperative eGFR. In summary, we validated our original trial conclusions by finding that intraoperative use of mannitol does not improve either short- or long-term renal function in patients undergoing NSS. Specifically, there is no evidence that comorbidities, including lower preoperative eGFR, modify the effect of mannitol. PATIENT SUMMARY: Use of mannitol at the time of partial nephrectomy does not improve either short- or long-term renal function even in patients with comorbidities, including lower preoperative renal function. The routine use of intraoperative mannitol should be discontinued.

Mannitol and Hypertonic Saline Reduce Swelling and Modulate Inflammatory Markers in a Rat Model of Intracerebral Hemorrhage.

BACKGROUND: Spontaneous intracerebral hemorrhage (ICH) leaves most survivors dependent at follow-up. The importance of promoting M2-like microglial responses is increasingly recognized as a key element to ameliorate brain injury following ICH. The osmotherapeutic agents, mannitol and hypertonic saline (HTS), which are routinely used to reduce intracranial pressure, have been shown to reduce neuroinflammation in experimental ischemic and traumatic brain injury, but anti-inflammatory effects of osmotherapies have not been investigated in ICH. METHODS: We studied the effects of iso-osmotic mannitol and HTS in rat models of ICH utilizing high-dose and moderate-dose collagenase injections into the basal ganglia, associated with high and low mortality, respectively. We studied the effects of osmotherapies, first given 5 h after ICH induction, and then administered every 12 h thereafter (4 doses total). Immunohistochemistry was used to quantify microglial activation and polarization. RESULTS: Compared to controls, mannitol and HTS increased plasma osmolarity 1 h after infusion (301 ± 1.5, 315 ± 4.2 and 310 ± 2.0 mOsm/kg, respectively), reduced mortality at 48 h (82, 36 and 53%, respectively), and reduced hemispheric swelling at 48 h (32, 21, and 17%, respectively). In both perihematomal and contralateral tissues, mannitol and HTS reduced activation of microglia/macrophages (abundance and morphology of Iba1 + cells), and in perihematomal tissues, they reduced markers of the microglia/macrophage M1-like phenotype (nuclear p65, TNF, and NOS2), increased markers of the microglia/macrophage M2-like phenotype (arginase, YM1, and pSTAT3), and reduced infiltration of CD45 + cells. CONCLUSIONS: Repeated dosing of osmotherapeutics at regular intervals may be a useful adjunct to reduce neuroinflammation following ICH.

Mannitol reduces nephron loss after warm renal ischemia in a porcine model.

BACKGROUND: Mannitol has been employed to ameliorate renal warm ischemia damage during partial nephrectomy, however, there is limited scientific evidence to support the use of mannitol during partial nephrectomy. The objective of the present study was to investigate the glomerular number after renal warm ischemia, with and without the use of mannitol in a Pig Model. METHODS: Twenty-four male pigs were assigned into three groups. Eight animals were allocated to the sham group that was subjected to laparoscopic dissection of the left renal hilum, without renal ischemia. Eight animals were allocated to the ischemia group that had the left renal hilum clamped for 30 min through laparoscopic access. Eight animals received mannitol (250 mg/kg) before the occlusion of renal hilum for 30 min. The kidneys were collected after the euthanasia of the pigs 21 days post surgery. The right kidney was utilized as a self-control for each animal. Serum creatinine, urea levels, the weight and volume of the kidneys were measured. Glomerular volumetric density, volume-weighted glomerular volume, and cortical volume were quantified through stereological methods and employed to determine the number of nephrons per kidney. Student's t test and ANOVA were used for statistical analysis. RESULTS: In the ischemia group, the left kidney recorded a reduction of 24.6% (290, 000 glomeruli) in the number of glomeruli in comparison to the right kidney. Kidneys subjected to ischemia also displayed decreased weight and volume in comparison to the sham and mannitol groups. No difference was observed between the left and right kidneys from the sham and mannitol groups. Further, no distinction in serum creatinine and urea among the groups was observed. CONCLUSION: The use of mannitol significantly reduces nephron loss during warm ischemia in pigs.

Effect of Mannitol on Ultrasonographically Measured Optic Nerve Sheath Diameter as a Surrogate for Intracranial Pressure During Robot-Assisted Laparoscopic Prostatectomy with Pneumoperitoneum and the Trendelenburg Position.

INTRODUCTION: CO2 pneumoperitoneum and the steep Trendelenburg position during robot-assisted laparoscopic prostatectomy (RALP) can increase intracranial pressure (ICP). Mannitol is widely used to treat increased ICP. However, no studies to date have specifically evaluated the effect of mannitol on ICP in patients undergoing RALP. Ultrasonographic measurement of the optic nerve sheath diameter (ONSD) is considered a reliable technique to noninvasively evaluate the ICP. Therefore, this study compared ONSDs as a surrogate for ICP before and after mannitol administration in prostate cancer patients undergoing RALP. METHODS: Mannitol (0.5 g/kg) was administered after pneumoperitoneum establishment and shifting to the Trendelenburg position. ONSDs were measured at six predetermined time points: 10 minutes after anesthesia induction (T0); 5 minutes after pneumoperitoneum and the Trendelenburg position before mannitol administration (T1); 30 minutes (T2), 60 minutes (T3), and 90 minutes (T4) after completion of mannitol administration during pneumoperitoneum and the Trendelenburg position; and at skin closure in the supine position (T5). Moreover, intraoperative hemodynamic and respiratory variables were evaluated simultaneously. RESULTS: Thirty-six patients were analyzed. ONSDs were significantly lower at T2, T3, and T4 than at T1 (all p < 0.001), with the greatest decrease observed at T4 compared with T1 (4.46 ± 0.2 mm vs 4.81 ± 0.3 mm, p < 0.001). Regional cerebral oxygen saturation, cardiac output, corrected flow time, peak velocity, body temperature, arterial CO2 partial pressure, peak airway pressure, plateau airway pressure, dynamic compliance, and static compliance were not significantly different during pneumoperitoneum and the Trendelenburg position; however, mean arterial blood pressure and heart rate were significantly different. CONCLUSIONS: Mannitol decreases the ONSD in patients undergoing RALP with CO2 pneumoperitoneum and the steep Trendelenburg position. This result provides useful information on the beneficial effects of mannitol administration on prostate cancer patients who may develop increased ICP during RALP.

Renal tubular epithelial cells injury induced by mannitol and its potential mechanism.

Administration of mannitol with high dose could induce extensive isometric renal proximal tubular vacuolization and acute renal failure in clinic. We previously demonstrated that mannitol-induced human kidney tubular epithelial cell (HK-2) injury. The objective of our present work was to further study the cytotoxicity of mannitol in HK-2 cells and its potential mechanism. Cell viability was assessed by an MTT method. Cell morphological changes were observed. Furthermore, levels of malondialdehyde (MDA) and glutathione (GSH) were measured. Flow cytometry was performed to determine cell apoptosis by using Annexin V-FITC and PI. In addition, the F-actin of cells was labeled by FITC-Phalloidin for observation of cytoskeleton. The MTT assay displayed that the cell viability decreased significantly in a dose- and time-dependent manner. The morphological changes were observed, including cell membrane rapture and cell detachment. The GSH concentration in HK-2 cells decreased dramatically in mannitol treatment group, while MDA content increased significantly. The results of flow cytometry indicated that apoptotic percentages of HK-2 cells increased in 250 mmol/L mannitol treatment group. After treatment with 250 mmol/L mannitol for 48 h, HK-2 cells showed disorganization of cytoskeleton and even exhibited a totally destroyed cytoskeleton. Therefore, high dose of mannitol has a toxic effect on renal tubular epithelial cells, which might be attributed to oxidative stress, destroyed cellular cytoskeleton and subsequent cell apoptosis.

Comparison of 3% Hypertonic Saline and 20% Mannitol for Reducing Intracranial Pressure in Patients Undergoing Supratentorial Brain Tumor Surgery: A Randomized, Double-blind Clinical Trial.

BACKGROUND: In the present study, we hypothesized that 3% hypertonic saline (HS) is more effective than 20% mannitol to reduce intracranial pressure (ICP) and to modify brain bulk in patients undergoing an elective supratentorial craniotomy. MATERIALS AND METHODS: After institutional review board approval, patients scheduled to undergo supratentorial craniotomy were enrolled into this prospective, randomized, double-blind study. The patients were monitored for routine hemodynamic parameters, depth of anesthesia, and ICP. They received 5 mL/kg 20% mannitol (n=20) or 3% HS (n=19) as infusion for 15 minutes. The patients' ICP values were monitored during hypertonic fluid infusion and throughout 30 minutes after infusion as a primary outcome. Secondary outcomes were hemodynamic variables, serum sodium value, blood gases, and surgeon brain relaxation assessment score (1=relaxed, 2=satisfactory, 3=firm, 4=bulging). In addition, the length of intensive care unit and hospital stay were recorded. RESULTS: Demographic and tumor characteristics were similar between groups. The basal (before hypertonic infusion, ICPT0) and last (30 min after hypertonic infusion finished, ICPT45) ICP values were 13.7±3.0 and 9.5±1.9 mm Hg, respectively, for the M group, which were comparable with the corresponding levels of 14.2±2.8 and 8.7±1.1 mm Hg in the HS group (P>0.05). The median amount of ICP reduction between T0 and T45 timepoints were 4 (1 to 7) and 5 (1 to 9) mm Hg for group M and group HS, respectively (P=0.035). Baseline central venous pressure, pulse pressure variation, and serum sodium and lactate values were similar between groups, but the last measured pulse pressure variation and lactate value were lower, and sodium value was higher in group HS than in group M (P<0.05). Duration of hospital and intensive care unit stay were similar between groups. CONCLUSIONS: Our results suggest that 3% HS provided more effective ICP reduction than 20% mannitol during supratentorial brain tumor surgery.

The renoprotective effects of mannitol and udenafil in renal ischemia-reperfusion injury model.

PURPOSE: The aim of this study was to investigate and compare the effects of udenafil and mannitol in an experimental renal ischemia-reperfusion (I/R) injury model. MATERIALS AND METHODS: A total of 64 female Wister Albino rats were used. Right nephrectomy was performed in all groups. In the control group; I/R injury was not performed. In the I/R group; left renal pedicle was clamped for 45 minutes and then underwent 60 minutes and 24 hours of reperfusion. In the mannitol group; 1 mL 20% mannitol was given intravenously 15 minutes before clamping. In the udenafil group; 10-mg/kg udenafil was given orally 1 hour before clamping. Creatinine (Cr), blood urea nitrogen (BUN), Cr clearance, malondialdehyde, neutrophil gelatinase associated lipocalin (NGAL), histological examination and DNA damage (Comet Assay method) levels were compared in tissue, serum and urine samples. RESULTS: Udenafil had a better protective effect than mannitol according to biochemical parameters (Cr, BUN, Cr clearance, and NGAL levels) and histopathological findings when compared with the I/R group. In the Comet sampling analysis no significant difference was detected. CONCLUSIONS: Udenafil has a better renoprotective effect than mannitol against I/R injury and this effect supports more functional improvements. Further clinical trials are needed to demonstrate those effects and clinical utility of udenafil for that purpose in humans.

Isosorbide-Induced Decompression Effect on the Scala Media: Participation of Plasma Osmolality and Plasma Arginine Vasopressin.

OBJECTIVE: The correlation between the isosorbide-induced decompression effect on the endolymphatic space and plasma osmolality (p-OSM) or plasma arginine vasopressin (p-AVP) was investigated on comparing two different dosages of isosorbide (2.8 and 1.4 g/kg) to elucidate why the decompression effect is delayed with a large dose of isosorbide. MATERIALS AND METHODS: Two experiments were performed using 80 guinea pigs. Experiment 1 was designed to morphologically investigate the sequential influence of the oral intake of 1.4- and 2.8-g/kg doses of isosorbide on the endolymphatic volume. The animals used were 50 guinea pigs (control: 10, experimental: 40). All animals underwent surgical obliteration of the endolymphatic sac of the left ear. One month after the surgery, control animals were sacrificed 3 hours after the intake of distilled water, and experimental animals were sacrificed 3 and 6 hours after the isosorbide intake. All of the left temporal bone served for the quantitative assessment of changes in the endolymphatic space, and the cross-sectional area of the scala media was measured from the mid-modiolar sections of the cochlea.Experiment 2 was designed to investigate changes in p-OSM and p-AVP levels 3 hours after the oral intake of isosorbide. Animals used were 15 guinea pigs (control: 5, experimental: 10). The control group received the oral administration of distilled water (4 ml/kg), and the experimental animals were subdivided into two groups consisting of 10 animals each by the dosage of isosorbide (1.4 or 2.8 g/kg). All animals were sacrificed for the measurement of p-OSM and p-AVP concentrations 3 hours after the intake of water or 70% isosorbide solution. RESULTS: Morphologically, an isosorbide-induced decompression effect was noted in animals with both 1.4- and 2.8-g/kg doses of isosorbide. According to the regression analysis, however, the volumetric decrease of the endolymphatic space was more evident in cases with the small dose (1.4 g/kg) 3 hours after the intake (analysis of covariance [ANCOVA], p < 0.001). Six hours after, the decompression effect was significantly greater in cases with the large dose (2.8 g/kg) (ANCOVA, p < 0.001).Isosorbide intake caused a rise in p-OSM levels dose-dependently. The Cochran-Cox test revealed that the differences in the mean values among control and isosorbide groups were significant (p < 0.01). Regarding the p-AVP level, a significant increase was evident in cases with the large dose (2.8 g/kg) (p < 0.01, Cochran-Cox test), and not in cases with the small dose (1.4 g/kg). CONCLUSION: An isosorbide-induced decompression effect of the endolymphatic space was evident in spite of two different dosages of isosorbide (2.8 and 1.4 g/kg). Three hours after the isosorbide intake, however, the decompression effect was more marked in the group with the small dose (1.4 g/kg). Since significant rises in p-OSM and p-AVP were evident in the group with the large dose, this early rise of p-AVP due to dehydration seems to be the major reason for the delayed decompression effect in cases with a large isosorbide intake.

Equiosmolar Solutions of Hypertonic Saline and Mannitol Do Not Impair Blood Coagulation During Elective Intracranial Surgery.

BACKGROUND: The authors investigated the effect of equiosmolar, equivolemic solutions of 3% hypertonic saline (HS) and 20% mannitol on blood coagulation assessed by rotational thromboelastometry (ROTEM) and standard coagulation tests during elective craniotomy. METHODS: In a prospective, randomized, double-blind trial, 40 patients undergoing elective craniotomy were randomized to receive 5 mL/kg of either 20% mannitol or 3% HS for intraoperative brain relaxation. Fibrinogen, activated partial thromboplastin time, prothrombin time, hemoglobin, hematocrit, and platelet count were simultaneously measured intraoperatively with ROTEM for EXTEM, INTEM, and FIBTEM analysis. ROTEM parameters were: clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF), and α-angle. RESULTS: No significant differences between groups were found in ROTEM variables CT, CFT, MCF, α-angle (EXTEM and INTEM), and MCF (FIBTEM) nor standard coagulation tests. ROTEM parameters did not show changes after administration of hyperosmolar solutions relating to basal values, except for an increase of CFT EXTEM (118±28 vs. 128±26 s) and decrease of CT INTEM (160±18 vs. 148±15 s) with values within normal range. Significant decreases from baseline levels were observed for hematocrit (-7%), platelet count (-10%), and fibrinogen (-13%) after HS infusion, and hematocrit (-9%), platelet count (-13%), and fibrinogen (-9%) after mannitol infusion, but remaining normal. CONCLUSIONS: The use of 5 mL/kg of equiosmolar solutions of 3% HS and 20% mannitol applied to reach a brain relaxation during elective craniotomy does not induce coagulation impairment as evidenced by ROTEM and standard coagulation tests.

Effects of acetaminophen and mannitol on crush injuries in rats: An experimental study.

BACKGROUND: The present objective was to evaluate effects of acetaminophen and mannitol on renal function and histopathology in crush injuries. METHODS: Thirty-six rats weighing 370-400 g each were used. No surgery was performed on the first (control) group. The gastrocnemius muscle regions of each rat in the remaining 5 groups were compressed for 2 or 24 hours. In the 4th group, 100 mg/kg acetaminophen was intraperitoneally administered. In the 5th group, 1 g/kg mannitol was administered. In the 6th group, 100 mg/kg acetaminophen and 1 g/kg mannitol were administered. RESULTS: No statistically significant differences were observed among the treatment groups in terms of sodium, potassium, alanine aminotransferase (ALT), and average creatinine clearance values. Hydropic degeneration, tubular necrosis, presence of immunoperoxidase and myoglobin, tubulus epithelial cell degeneration, and presence of PAS-dyed material in tubular lumen was more prominently decreased in the acetaminophen group than the mannitol group. Improvement was observed in the group that was administered both drugs, compared to the mannitol-only group, though findings were still worse than those of the group administered acetaminophen only. CONCLUSION: In crush injuries, acetaminophen improves histopathological renal damage better than mannitol. When used in conjunction with mannitol, the toxic effect of acetaminophen on the liver is decreased.

Mannitol versus hypertonic saline: Safety and efficacy of mannitol and hypertonic saline in sputum induction and bronchial hyperreactivity assessment.

Eosinophilic asthma phenotype predicts good response to corticosteroids and associates to asthmatic exacerbations. Sputum induction by hypertonic saline (HS) inhalation is technically demanding. Bronchial hyperresponsiveness (BHR) to osmotic agents indirectly mirrors active airway inflammation. We compared the safety and ability of HS and mannitol to induce sputum and measure BHR. We evaluated the stability of inflammatory phenotypes. We studied 35 non-smoking asthmatics randomized to undergo HS and mannitol challenges on 2 days 1 week apart. Sputum was sampled for cell analysis and phenotyped as eosinophilic (≥3% eosinophils) and non-eosinophilic (<3%) asthma. Nineteen subjects had BHR to mannitol and nine of them also had BHR to HS. Drops in forced expiratory volume in 1 s were higher from HS challenge than from mannitol challenge. Adequate sputum samples were obtained from 80% subjects (68% mannitol and 71% HS). Eosinophils and macrophages from both challenges correlated. Neutrophils were higher in sputum from HS. Ninety percent samples were equally phenotyped with HS and mannitol. Fractional exhaled nitric oxide, sputum eosinophils and BHR correlated in both challenges. HS and mannitol showed similar capacity to produce valuable sputum samples. BHR to both osmotic stimuli partially resembled airway eosinophilic inflammation but mannitol was more sensitive than HS to assess BHR. Eosinophilic phenotype remained stable in most patients with both stimuli.

Hypertonic saline in elevated intracranial pressure: past, present, and future.

Hypertonic Saline (HS) has been a proven and effective therapy and a safe alternative to mannitol in patients with increase intracranial pressure (ICP). We hereby present a case of 25-year-old women with intracranial bleed secondary to right parietal arteriovenous malformation. Patient underwent surgery for evacuation of hematoma and resection of arteriovenous malformation. Post- operative course was complicated by recurrent episodes of elevated ICP. She received total of 17 doses of 23.4% HS and 30 doses of mannitol with good outcome. Despite reluctance from some clinicians to use HS, hypertonic saline seems to be a safe and effective therapy.

Hyperosmolality-mediated peritoneal microvascular vasodilation is linked to aquaporin function.

Glucose-based peritoneal dialysis (PD) solutions dilate the parietal and visceral peritoneal microvasculature by endothelium-dependent mechanisms that primarily involve hyperosmolality. This PD-mediated dilation occurs by active intracellular glucose uptake and adenosine Al receptor activation, and by hyperosmolality-stimulated glibenclamide-sensitive potassium channels. Both pathways invoke NO as a second messenger for vasodilation. We hypothesized that during crystalloid-induced osmosis, the osmotic water flux through the transendothelial water-exclusive aquaporin 1 (AQP1) channels is the primary mechanism whereby the endothelium is being stimulated to instigate hyperosmolality-driven vasodilation. Four microvascular levels (diameters in the range 6 - 100 microm) were visualized by intravital videomicroscopy of the terminal ileum in anesthetized rats. Microvascular diameters and flow were measured after topical exposure to a 5% hypertonic mannitol or 2.5% glucose-based PD solution, at baseline and after brief tissue pre-treatment (with 0.1% glutaraldehyde for 10 seconds) or after combined tissue pre-treatment and pharmacologic blockade of AQP1 with HgCl2 (100 micromol/L). Vascular endothelial integrity was verified by the response to acetylcholine (10(-4) mol/L) and sodium nitroprusside (10(-4) mol/L). The hyperosmolar solutions both caused rapid and sustained vasodilation at all microvascular levels, which was not altered by tissue pre-treatment. Inhibition of AQP1 completely abolished the mannitol-induced vasodilation and markedly attenuated the PD fluid-mediated vasodilation. Neither glutaraldehyde pre-treatment nor HgCl2 affected tissue integrity or endothelial cell function. We conclude that the peritoneal microvascular vasodilation caused by hyperosmolar PD fluid is instigated by the osmotic water flux through AQP1. Clinical PD solutions have components other than hyperosmolality that can induce endothelium-dependent peritoneal microvascular vasodilation independent of the AQP1-mediated osmosis.

Cannulation of the internal carotid artery in mice: a novel technique for intra-arterial delivery of therapeutics.

We have developed a novel minimally invasive technique for the intra-arterial delivery of therapeutics to the mouse brain. CD-1 mice were anesthetized and placed in a lateral decubitus position. A 10mm midline longitudinal incision was made over the thyroid bone. The omohyoid and sternomastoid muscles were retracted to expose the common carotid artery and external carotid artery (ECA). To maximize delivery of administered agents, the superior thyroid artery was ligated or coagulated, and the occipital artery and the pterygopalatine artery (PPA) were temporarily occluded with 6-0 prolene suture. The ECA was carefully dissected and a permanent ligature was placed on its distal segment while a temporary 6-0 prolene ligature was placed on the proximal segment in order to obtain a flow-free segment of vessel. A sterilized 169 µm outer diameter polyimide microcatheter was introduced into the ECA and advanced in retrograde fashion toward the carotid bifurcation. The catheter was then secured and manually rotated so that the microcatheter tip was oriented cephalad in the internal carotid artery (ICA). We were able to achieve reproducible results for selective ipsilateral hemispheric carotid injections of mannitol mediated therapeutics and/or gadolinium-based MRI contrast agent. Survival rates were dependent on the administered agent and ranged from 78 to 90%. This technique allows for reproducible delivery of agents to the ipsilateral cerebral hemisphere by utilizing anterograde catheter placement and temporary ligation of the PPA. This method is cost-effective and associated with a low rate of morbimortality.

Mannitol enhances antibiotic sensitivity of persister bacteria in Pseudomonas aeruginosa biofilms.

The failure of antibiotic therapies to clear Pseudomonas aeruginosa lung infection, the key mortality factor for cystic fibrosis (CF) patients, is partly attributed to the high tolerance of P. aeruginosa biofilms. Mannitol has previously been found to restore aminoglycoside sensitivity in Escherichia coli by generating a proton-motive force (PMF), suggesting a potential new strategy to improve antibiotic therapy and reduce disease progression in CF. Here, we used the commonly prescribed aminoglycoside tobramycin to select for P. aeruginosa persister cells during biofilm growth. Incubation with mannitol (10-40 mM) increased tobramycin sensitivity of persister cells up to 1,000-fold. Addition of mannitol to pre-grown biofilms was able to revert the persister phenotype and improve the efficacy of tobramycin. This effect was blocked by the addition of a PMF inhibitor or in a P. aeruginosa mutant strain unable to metabolise mannitol. Addition of glucose and NaCl at high osmolarity also improved the efficacy of tobramycin although to a lesser extent compared to mannitol. Therefore, the primary effect of mannitol in reverting biofilm associated persister cells appears to be an active, physiological response, associated with a minor contribution of osmotic stress. Mannitol was tested against clinically relevant strains, showing that biofilms containing a subpopulation of persister cells are better killed in the presence of mannitol, but a clinical strain with a high resistance to tobramycin was not affected by mannitol. Overall, these results suggest that in addition to improvements in lung function by facilitating mucus clearance in CF, mannitol also affects antibiotic sensitivity in biofilms and does so through an active, physiological response.

Decreased risk of acute kidney injury with intracranial pressure monitoring in patients with moderate or severe brain injury.

OBJECT: The authors undertook this study to evaluate the effects of continuous intracranial pressure (ICP) monitoring-directed mannitol treatment on kidney function in patients with moderate or severe traumatic brain injury (TBI). METHODS: One hundred sixty-eight patients with TBI were prospectively assigned to an ICP monitoring group or a conventional treatment control group based on the Brain Trauma Foundation guidelines. Clinical data included the dynamic changes of patients' blood concentrations of cystatin C, creatinine (Cr), and blood urea nitrogen (BUN); mannitol use; and 6-month Glasgow Outcome Scale (GOS) scores. RESULTS: There were no statistically significant differences with respect to hospitalized injury, age, or sex distribution between the 2 groups. The incidence of acute kidney injury (AKI) was higher in the control group than in the ICP monitoring group (p < 0.05). The mean mannitol dosage in the ICP monitoring group (443 ± 133 g) was significantly lower than in the control group (820 ± 412 g) (p < 0.01), and the period of mannitol use in the ICP monitoring group (3 ± 3.8 days) was significantly shorter than in the control group (7 ± 2.3 days) (p < 0.01). The 6-month GOS scores in the ICP monitoring group were significantly better than in the control group (p < 0.05). On the 7th, 14th, and 21st days after injury, the plasma cystatin C and Cr concentrations in the ICP-monitoring group were significantly higher than the control group (p < 0.05). CONCLUSIONS: In patients with moderate and severe TBI, ICP-directed mannitol treatment demonstrated a beneficial effect on reducing the incidence of AKI compared with treatment directed by neurological signs and physiological indicators.