Clinical insights into adipsic diabetes insipidus: a large case series

OBJECTIVE

Adipsic diabetes insipidus (DI) causes significant hypernatraemia. Morbidity and mortality data for patients with adipsic DI have been previously published as single case reports, rather than as formal trials or case series from units with established management protocols. Our objective was to describe morbidity and mortality in patients with adipsic DI attending a tertiary referral centre, representing the largest reported series of adipsic DI, and to suggest management protocols for such patients, based on our extensive experience of this condition.

DESIGN

Arginine vasopressin (AVP) responses to hypotension were recorded during trimetaphan infusion. Sleep abnormalities were identified using overnight oximetry or polysomnography. Case-note analysis defined other clinical abnormalities including seizures and thrombotic episodes. Important clinical points for the management of these patients are highlighted.

PATIENTS

Thirteen patients with adipsic DI defined by thirst and plasma AVP responses to hypertonic saline infusion.

RESULTS

All patients had absent AVP and thirst responses to osmotic stimulation, with subnormal water intake. Five patients had absent AVP responses to hypotension; the remainder had normal responses. Eight patients were obese [body mass index (BMI) > 30 kg/m(2)], and three were overweight (BMI > 25 kg/m(2)). Seven patients had sleep apnoea, of whom three died at 36 years or younger. Four patients developed venous thrombosis during episodes of hypernatraemia. Two patients had thermoregulatory dysfunction and seven patients had seizure activity.

CONCLUSION

Adipsic DI is associated with significant morbidity and mortality. Physicians should be aware of associated, treatable hypothalamic abnormalities such as obesity, sleep apnoea, seizures and thermoregulatory disorders when managing adipsic DI.

Selected zinc metabolism parameters in women with arterial hypotension

In the present study, differences between selected zinc parameters in healthy women and arterial hypotension patients were compared. The patients had baseline systolic blood pressure that did not surpass 100 mm Hg. During the orthostatic test, a decrease of over 20 mm Hg was seen and the patients reported dizziness, limpness, and palpitations. The patients had higher levels of lymphocyte zinc than those of the controls and exhibited a positive correlation between serum zinc and the ouabain-dependent zinc efflux from lymphocytes (r = 0.49), and, in turn, this efflux was negatively correlated to the serum aldosterone level (r = -0.35). Except for the differences in their systolic blood pressure and lymphocyte zinc, none of the tested zinc metabolism parameters showed significant differences between the patients and the controls. As in arterial hypertension, the obtained results indicate that zinc plays a significant role in regulation of arterial blood pressure.

Propofol causes more hypotension than etomidate in patients with severe aortic stenosis: a double-blind, randomized study comparing propofol and etomidate

BACKGROUND

Vasodilatation and hypotension are thought to be harmful in patients with severe aortic stenosis. Etomidate is preferred to propofol for anaesthesia induction in haemodynamically unstable patients, but may disturb cortisol synthesis. We assessed the haemodynamic effects of etomidate vs. propofol as anaesthesia induction agents, and the effects of these drugs on cortisol concentrations, in patients with severe aortic stenosis. The main end-point of the study was the incidence of hypotension.

METHODS

Sixty-six patients with severe aortic stenosis scheduled for elective aortic valve replacement were enrolled in the study. The patients were randomized to receive either propofol or etomidate for induction of anaesthesia. Haemodynamic parameters, i.e. mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI), were measured. If MAP decreased below 70 mmHg for more than 30 s, phenylephedrine was administered. Serum cortisol concentrations were also measured.

RESULTS

MAP decreased in all patients (P < 0.001). MAP decreased to a greater extent in patients receiving propofol than in those receiving etomidate (P = 0.006). Patients receiving propofol needed phenylephedrine more often than those receiving etomidate (20/30 vs. 8/30, P = 0.002). CI and PCWP decreased in both groups (P < 0.001), with no difference between the groups. Patients receiving etomidate had a lower serum cortisol concentration immediately after the operation than those receiving propofol (P < 0.001), but no differences between the groups were observed on the first post-operative morning.

CONCLUSION

Propofol is twice as likely as etomidate to evoke hypotension in anaesthesia induction of patients with severe aortic stenosis; however, etomidate transiently decreases post-operative serum cortisol concentrations.

Oxycodone Accumulation in a Hemodialysis Patient

Oxycodone and oxycodone-containing analgesics are often used for the relief of pain. In the presence of renal dysfunction, the half-life of oxycodone and metabolites can be prolonged. We describe the case of a 41-year-old chronic hemodialysis patient who received multiple doses of oxycodone/acetaminophen resulting in accumulation of the medication and consequent lethargy, hypotension and respiratory depression. These adverse effects were reversed with multiple bolus doses of naloxone, followed by a continuous infusion administered for 45 hours. Utilizing the Naranjo probability scale, the patient had a "probable" adverse drug reaction to the oxycodone. Oxycodone should be used with caution in patients with chronic renal failure.

The influence of sodium profiling on blood volume and intradialytic hypotension in patients on maintenance hemodialysis

An accurate evaluation of water content in the body of hemodialyzed patients seems to be an important problem in chronic dialysotherapy. Acute intradialytic hypotension observed in 20-33% of hemodialysis patients is a very common complication of this kind of renal replacement therapy. The study was performed in 40 uremic patients, treated with hemodialysis at the Nephrology Clinic of the University Hospital in Cracow. In every patient, 3 model dialysis sessions were carried out. Total fluid removal was the same during every hemodialysis. The first model hemodialysis (HD1) was performed with constant dialysate sodium concentration (140 mmol/L), the second (HD2) with linear and the third (HD3) with expotential decrease of dialysate sodium concentration (from 144 to 136 mmol/L). Every hemodialysis was also monitored continuously with Crit-Line 2 R system (In-Line Diagnostics, Riverdale, UT). Before and after the first model hemodialysis (HD1), ultrasound examination of abdominal cavity was performed. The measurement of inferior vena cava diameter (mm), circumference (mm), area (mm2), at hepatic veins orifice-level, on expiration was performed. The fluid removal during the first model hemodialysis resulted in significant reduction of the vena cava inferior diameter, circumference and area, measured with ultrasound on expiration. The statistically significant lower fall of blood volume after the first and second hour of the second model hemodialysis session (HD2) was observed when compared to the first hemodialysis (HD1) - p<0.05 was observed. The statistically significant lower frequency of hypotension during the second hemo-dialysis session (HD2) as compared to HD1 (chi2=5.25 p<0.05). Differences among HD1 and HD3 and HD2 and HD3 did not reach statistical significance. The monitoring of hemodialysis with the Crit-Line instrument permits for optimalization of dry weight of dialyzed patients and allows reaching higher ultrafiltration rates during dialysis without hypotensive episodes. The changes in the blood volume, approximately 5% per one hour of dialysis session are an optimal value for these patients.

[Acute intoxication with clonidine--a case report]

The case of a 24-year-old female who ingested 45 tablets of clonidine (Iporel á 0.075 mg) in the total dose of 3,375 mg in suicidal attempt was described. At the admission to the hospital the patient had complained of drowsiness and weakness. She was conscious but somnolent. Minimal blood pressure was 90/50 mmHg. The patient was treated with gastric lavage and crystalloids infusion. During two days of observation the symptoms were rapidly retreated.

Serum chromogranin A concentration and intradialytic hypotension in chronic haemodialysis patients

AIM

The aim of this study was to investigate the influence of haemodialysis on plasma chromogranin A (CgA) concentration and to assess the relationship between CgA, blood pressure, occurrence of intradialytic hypotension episodes and residual renal function, respectively.

METHODS

The study included 38 chronic haemodialysis patients (24 M, 14 F; mean age 56.2+/-13.6 years). Plasma CgA and blood pressure were measured before and after a mid-week dialysis. Control group included 10 age- and sex-matched healthy subjects.

RESULTS

Plasma CgA levels were on average 50-fold higher in HD patients than in the controls (699+/-138 vs. 14+/-6 U/L). In HD patients plasma CgA corrected for ultrafiltration rates significantly increased (to 836+/-214 U/L, P<0.001) at the end of dialysis procedure. In patients with (n=8) and without frequent symptomatic intradialytic hypotension episodes predialysis values of CgA were similar (701+/-169 vs. 698+/-132 U/L) but post-dialysis were significantly lower in the former group (746+/-312 vs. 860+/-177 U/L; P=0.03) despite a similar rate of ultrafiltration (2675+/-1009 and 2583+/-1311 ml, respectively). Accordingly, in patients with intradialytic hypotension an increase of plasma CgA during dialysis was also much lower than in patients without hypotension (45+/-81 vs. 163+/-144 U/L; P=0.001).

CONCLUSIONS

CgA undergoes marked accumulation in renal failure. The increase of plasma CgA during dialysis is impaired in subjects with intradialytic hypotension episodes, which confirms the role of autonomic dysfunction in the pathogenesis of this complication.

Ketamine inhibits fetal ACTH responses to cerebral hypoperfusion

The present study tested the effect of ketamine on the fetal reflex responses of late-gestation sheep to brachiocephalic occlusion (BCO), a stimulus that mimics the reduction in cerebral blood flow that results from severe fetal hypotension. Ketamine, a dissociative anesthetic and known noncompetitive antagonist of N-methyl D-aspartate (NMDA) receptors, has previously been shown to impair chemoreceptor responsiveness. Studies from this laboratory suggest that fetal reflex ACTH responses to hypotension are largely mediated by chemoreceptors; therefore, we hypothesized that ketamine would inhibit the reflex hormonal response to BCO. Chronically catheterized fetal sheep were subjected to acute cerebral hypoperfusion through occlusion of the brachiocephalic artery. Fetal blood pressure and heart rate were continuously recorded, and fetal blood samples drawn during the experiment were analyzed with specific hormone assays. Our results demonstrate that ketamine attenuates hemodynamic responses to cerebral hypoperfusion and is a potent inhibitor of ACTH and proopiomelanocortin (POMC)/pro-ACTH release. These data support the hypothesis that fetal reflex responses hypotension are chemoreceptor mediated. Given the potency with which ketamine inhibits ACTH response to fetal hypotension, we suggest that the use of ketamine or other anesthetic or analgesic drugs that block or otherwise interact with the NMDA-glutamate pathways, in late pregnancy or in preterm newborns be reconsidered.

Modulation of hypotensive effects of kinins by cathepsin K

Kinins are pro-inflammatory peptides, which participate in the maintenance of cardiovascular homeostasis, and play a key role in numerous diseases, including lung fibrosis and hypertension. Evidence has been provided recently for the presence of alternative mechanisms of bradykinin generation and/or degradation. Here we showed that cathepsin K may act as a potent kinin-degrading enzyme in bloodstream. Contrary to cathepsin L, cathepsin K attenuates kallikrein-induced decrease of rat blood pressure, and reduces the hypotensive effect of bradykinin in a dose-dependent manner. Moreover, we identified, by engineering the S2 subsite of both recombinant enzymes, two critical residues involved respectively in the kininase activity of cathepsin K, i.e. Tyr67/Leu205, versus kininogenase activity of cathepsin L, i.e. Leu67/Ala205. In conclusion, according to its ability to modulate hypotensive effects of kinins, we propose that cathepsin K is a kininase of biological relevance, in complement of well-documented neutral endopeptidase or angiotensin-converting enzyme.

Intraoperative hypotension and prolonged operative time as risk factors for slow graft function in kidney transplant recipients

BACKGROUND

Slow graft function (SGF) is an immediate post-operative complication of cadaveric kidney transplantation pre-disposing to acute rejection (AR) and lower graft survival. The objective of this study was to test whether intraoperative hypotension and/or prolonged operative time are risk factors for SGF in patients post-cadaveric kidney transplant.

METHODS

This was a single center retrospective case-control study of patients post-cadaveric kidney transplant performed at the University of Kansas Medical Center (KUMC) between January 2002 and February 2005. Data were retrieved from the United Network of Organ Sharing (UNOS) database.

RESULTS

One hundred and sixty patients underwent cadaveric kidney transplant. Intraoperative measurements including blood pressure and operative time were available in 94 patients of which 57 had immediate graft function (IGF) and 37 had SGF (defined as decline in serum creatinine (Cr) of <50% by day 3). In multivariate logistic regression analysis, intraoperative hypotension and prolonged operative time were additive independent risk factors for SGF. For every 5 mmHg increment decrease in blood pressure, the odds ratio (OR) for SGF was 1.28 (95% confidence interval (CI): 1.08-1.53) for systolic blood pressure (SBP), 1.38 (CI: 1.06-1.79) for diastolic blood pressure (DBP), and 1.51 (CI: 1.15-1.99) for mean arterial pressure (MAP). For every 30 min increase in operative time, the OR for SGF was 1.35 (CI: 1.07-1.71).

CONCLUSION

Intraoperative hypotension and prolonged operative time are independent risk factors for SGF in patients post-cadaveric kidney transplant.

Intradialytic changes of serum magnesium and their relation to hypotensive episodes in hemodialysis patients on different dialysates

Magnesium is a crucial mineral, involved in many important physiological processes. Magnesium plays a role of maintaining myocardial electrical stability in hemodialysis patients. Intradialytic hypotension is a common complication of dialysis and it is more common with acetate dialysate. The significance of the intradialytic changes of magnesium and their relation to parathyroid hormone (PTH) level and calcium changes during dialysis, and their relation to hypotensive episodes during dialysis are interesting. The aim of this work is to investigate the intradialytic changes of serum magnesium in chronic hemodialysis patients with different hemodialysis modalities and the relation to other electrolytes and to PTH, and also the relation to intradialytic hypotension. The present study was conducted on 20 chronic renal failure patients. All patients were on regular hemodialysis thrice weekly 4 hr each using acetate dialysate (group I). To study the effect of an acetate-based dialysate vs. a bicarbonate-based dialysate on acute changes of magnesium, calcium, phosphorus, and PTH during a hemodialysis session, the same patients were shifted to bicarbonate dialysis (group II). All patients were subjected to full history and clinical examination, predialysis laboratory assessment of blood urea nitrogen (BUN), serum creatinine, albumin, and hemoglobin, serial assessment of magnesium, calcium, phosphorus, and parathyroid hormone at the start of the hemodialysis session, 2 hr later, and at the end of the session, blood pH, and electrocardiogram (ECG) presession and postsession. All patients were urged to fix their dry weight, diet, and current medications. None of the patients had diabetes, neoplasia, liver disease, or cachexia, nor had they been recently on magnesium-containing drugs or previously parathyroidectomized. Hemodialysis sessions were performed by volumetric dialysis machines using the same electrolyte composition. Magnesium level significantly increased in the bicarbonate group at the end of dialysis (0 hr: 2.73+/-0.87, 2 hr: 3.21+/-1.1, and at 4 hr: 5.73+/-1.45 mg/dL, p value <0.01), while it significantly decreased in the acetate group (0 hr: 3.00+/-0.58, 2 hr: 2.26+/-0.39, 4 hr: 1.97+/-0.33 mg/dL, p value <0.01). Calcium level significantly increased in the bicarbonate group (p=0.024) but not in the acetate group. Phosphorus level significantly decreased in both acetate and bicarbonate groups. PTH level did not significantly change in either group, p value > or =0.05. Blood pH significantly increased, changing from acidic to alkaline pH, with both modalities of hemodialysis. ECG showed no significant changes during sessions with either type of dialysate. Hypotension was significantly higher in group I compared with group II (p=0.01), and this hypotension was positively correlated with a decrease in serum magnesium level in group I. Intradialytic changes in serum magnesium have no correlation with intradialytic changes in serum calcium or with PTH level. However, it was significantly correlated with hypotension during the dialysis session, especially with acetate dialysate. Further investigations are needed to determine whether or not this is true in patients using bicarbonate dialysis.

Antithrombin reduces endotoxin-induced hypotension by enhancing pulmonary sensory neuron activation in rats

We recently demonstrated that activation of the pulmonary sensory neurons plays a critical role in prevention of endotoxin-induced shock by releasing calcitonin gene-related peptide (CGRP) in rats. CGRP increased the endothelial production of prostacyclin (PGI(2)) in the lungs, thereby preventing endotoxin-induced shock response by inhibiting tumor necrosis factor-alpha (TNF-alpha) production. Since antithrombin (AT) enhances sensory neuron activation, we hypothesized that AT might reduce endotoxin-induced hypotension by enhancing the activation of pulmonary sensory neurons in rats. We examined this possibility using a rat model of endotoxin shock. AT-induced effects including reduction of hypotension (n = 5) and inhibition of induction of iNOS (n = 4 or 5) and TNF- alpha (n = 5) in the lungs of endotoxin-treated animals were completely reversed by pretreatment with capsazepine (CPZ) (n = 4 or 5), a vanilloid receptor antagonist, or CGRP(8-37), a CGRP receptor antagonist (n = 4 or 5). AT enhanced endotoxin-induced increases in lung tissue levels of CGRP (n = 4), but this effect of AT was not seen in animals pretreated with CPZ (n = 4). CGRP produced therapeutic effects (n = 5) similar to those induced by AT, and such therapeutic effects were completely abrogated by pretreatment with indomethacin (n = 4). AT increased CGRP release from cultured dorsal root ganglion neurons only in the presence of anandamide (n = 5), and AT-induced increase in CGRP release was not observed in the presence KT5720, an inhibitor of protein kinase A (n = 5). AT markedly increased intracellular levels of cAMP in the presence of anandamide (n = 5). These results strongly suggested that AT might reduce endotoxin-induced hypotension in rats by enhancing activation of sensory neurons via activation of protein kinase A.

Involvement of brain thromboxane A in hypotension induced by haemorrhage in rats

1. In the present study, we aimed to determine the involvement of brain thromboxane A2 (TXA2) in blood pressure decreases evoked by acute and/or graded haemorrhage in rats. 2. Sprague-Dawley rats were used throughout the study. Acute haemorrhage was achieved by withdrawing a total volume of 2.1 and 2.5 mL blood/100 g bodyweight over a period of 10 min. A microdialysis study was performed in a hypothalamic area to measure extracellular TXA2 levels. Graded haemorrhage was conducted successively by withdrawing carotid arterial blood (0.55 mL/100 g bodyweight) over a 10 s period four times (S1-S4) at 5 min intervals. Furegrelate (125, 250 and 500 microg), a TXA2 synthase inhibitor, was injected intracerebroventricularly (i.c.v.) 60 min before acute or graded haemorrhage was initiated. U-46619 (0.5, 1 and 2 microg, i.c.v.), a synthetic TXA2 analogue, was administered 5 min before acute haemorrhage (2.1 mL/100 g bodyweight). 3. Acute haemorrhage produced a severe and long-lasting decrease in blood pressure and had a tendency to increase heart rate. Both haemorrhage protocols (2.1 or 2.5 mL/100 g) generated similar approximate twofold increases in extracellular hypothalamic TXA2 levels. Intracerebroventricular furegrelate (250 microg) pretreatment completely blocked the TXA2 increases induced by acute haemorrhage. Furegrelate administration (100, 250 and 500 microg, i.c.v.) attenuated the fall in arterial pressure evoked by acute haemorrhage and caused significant increases in heart rate at all doses injected. 4. Graded haemorrhage progressively lowered arterial pressure and increased plasma vasopressin and adrenaline levels in the last period. Furegrelate-injected rats were greatly resistant to the hypotensive effect of haemorrhage for all degrees of blood removed. Plasma adrenaline and vasopressin levels were significantly elevated in furegrelate-pretreated rats compared with the saline-treated group during S2-S3 and S4, respectively. U-46619 administration caused small but statistically significant decreases in arterial pressure induced by haemorrhage. 4. The results show that acute hypotensive haemorrhage increases extracellular hypothalamic TXA2 levels. The increase in brain endogenous TXA2 levels involves a decrease in blood pressure evoked by haemorrhage because the blockade of TXA2 synthesis by furegrelate pretreatment attenuated the haemorrhagic hypotension. Increases in plasma adrenaline and vasopressin levels may mediate this effect.

Effects of post-treatment with direct hemoperfusion using a CTR column on mortality and inflammatory responses to endotoxin-induced shock in rats

BACKGROUND

To clarify the effects of post-treatment with direct hemoperfusion using a CTR column on the mortality and inflammatory responses to endotoxin-induced shock in rats.

METHODS

Thirty-six male rats were randomly assigned to 1 of 3 groups (n = 12/group): the endotoxemic group, receiving intravenous Escherichia coli endotoxin (15 mg/kg over 2 min); the control column group, treated without CTR for 120 min at 2 h after endotoxin injection, and CTR-post-treatment group, treated with CTR for 120 min at 2 h after endotoxin injection. Hemodynamics, arterial blood gases, and mortality were recorded for the 8-hour observation period, and plasma cytokine concentrations were measured every 4 h.

RESULTS

The mortality rates were 83, 83 and 33% for the endotoxemic, control column, and CTR post-treatment groups, respectively. The increases in IL-6 concentrations were less for the CTR post-treatment group than the other 2 groups.

CONCLUSION

The present study shows that CTR post-treatment inhibited hypotension and elevations in IL-6 concentrations, reducing the mortality rate of rats with endotoxin-induced shock.

The protective effect of low-dose dopamine on renal functions in hypotensive rats: an experimental study

BACKGROUND

The aim of this study was to investigate the effect of low-dose dopamine on markers of the renal functions in a rat model of hypotension.

METHODS

Forty Wistar rats were divided into control, hypotension, dopamine, and hypotension+dopamine groups. Hypotension was achieved by sodium-nitroprusside infusion. Samples were drawn for analysis during the two-hour study period.

RESULTS

Blood urea nitrogen levels were significantly increased in hypotension group during the early phase but this difference disappeared at the end of the second hour. Dopamine infusion had no effect on creatinine and potassium clearance. Despite the significance of improved sodium clearance in the hypotensive rats treated with dopamine, natriuresis did not occurred in the dopamine-only group.

CONCLUSION

It can be stated that low dose dopamine infusion at a rate of 0.5 microg kg(-1) min(-1) has a short-term preventive action against the increase of blood urea nitrogen during the early phase of pharmacologically induced hypotension.

Cardiac troponin T and cardiac dysfunction in extremely low-birth-weight infants

Extremely low-birth-weight (ELBW) infants frequently manifest signs of cardiac dysfunction requiring inotropic support. It is not clear if this is due to cardiac injury, which can be monitored by measuring cardiac troponin T (cTnT). We performed a nested prospective cohort study at a university level III neonatal intensive care unit. The study included 27 infants weighing between 500 and 999 g. Exclusion criteria included evidence of sepsis, use of postnatal steroids, and cardiac anomalies. Measurements included serum cTnT and echocardiogram in the first 48 hours of life. The mean serum cTnT level of the study population was 0.52 +/- 0.38 ng/ml. It was higher in those with lower Apgar scores (0.89 +/- 0.37 if 5-minute Apgar < 4 vs 0.36 +/- 0.26 ng/ml, p < 0.001) and correlated to initial base deficit (r = -0.37, p < 0.05). Infants who required inotropic support had higher cTnT levels than those who did not (0.73 +/- 0.43 vs 0.39 +/- 0.29 ng/ml, p < 0.03). cTnT concentrations did not relate to simultaneous echocardiographic measures of cardiac function. In ELBW infants, serum cTnT levels are higher than normally seen in term infants and adults, and they are higher in infants with greater perinatal stress as well as those who show evidence of cardiac dysfunction requiring pressor support.

Voglibose inhibits postprandial hypotension in neurologic disorders and elderly people

The authors examined blood pressure, glucose, insulin, and neurotensin before and after intake of 75 g glucose with or without voglibose in 28 neurologic patients and 20 healthy controls. Voglibose significantly prevented hypotension and neurotensin increment after glucose intake and had no influence on glucose or insulin increment. These results suggest that voglibose benefits postprandial hypotension.

Effects of intraduodenal glucose concentration on blood pressure and heart rate in healthy older subjects

The aims of this study were to determine whether the hypotensive and heart rate responses to small intestinal glucose infusion are dependent on the glucose concentration. Eight healthy subjects, aged 65-78 years, were studied on 3 separate days in random order. Each subject received intraduodenal infusions of 50 g of glucose in either 300 mL (16.7%), 600 mL (8.3%), or 1200 mL (4.1%) of saline (0.9%) at a rate of 3 kcal/min for 60 minutes (t = 0-60 minutes), followed by saline (0.9%) for a further 60 minutes (t = 60-120 minutes). During the infusions, blood pressure (systolic and diastolic) and heart rate were measured every 3 minutes, and blood glucose concentrations every 15 minutes. Systolic and diastolic blood pressure fell (P < .0001), and heart rate and blood glucose increased (P = .0001 for both) over time, during all 3 infusions. Between t = -2-120 minutes, there was no difference in systolic blood pressure (P = .20), diastolic blood pressure (P = .61), or heart rate (P = .09) over the study days. There was also no significant difference in the glycemic response to the infusions. We conclude that in healthy older subjects, glucose concentration does not affect the blood pressure or heart rate responses to intraduodenal glucose and that, therefore, the magnitude of the postprandial fall in blood pressure induced by oral glucose is likely to depend primarily on the small intestinal glucose load.

Successful reduced intensity allogeneic stem cell transplantation for systemic AL amyloidosis

No established treatments for systemic AL amyloidosis have been determined, and only four reports have described allogeneic stem cell transplantation for this disease. We report the case of a patient with orthostatic hypotension, diarrhea, nephrotic syndrome, and cardiac amyloidosis due to systemic AL amyloidosis. Reduced intensity allogeneic stem cell transplantation (RIST) was performed using a conditioning regimen comprising fludarabine 125 mg/m2 and melphalan 90 mg/m2. Hematologically complete remission and symptomatic improvement were obtained without severe transplantation-related complications. RIST may thus offer a useful treatment strategy for systemic AL amyloidosis complicated by cardiac amyloidosis.

Mechanotransduction and the homeostatic significance of maintaining blood viscosity in hypotension, hypertension and haemorrhage

The increase of plasma and blood viscosity is usually associated with pathological conditions; however, elevation of both parameters often results in increased perfusion and the lowering of peripheral vascular resistance. In extreme haemodilution, blood viscosity is too low and insufficient to maintain functional capillary density, a problem that in experimental studies is shown to be corrected by increasing plasma viscosity up to 2.2 cP. This effect is mediated by mechanotransduction-induced nitric oxide (NO) production via shear stress in the endothelium as shown by microelectrode perivascular measurements of NO concentration. Moderate elevations of blood viscosity by increasing haematocrit ( approximately 10%) result in comparable reductions of blood pressure and peripheral vascular resistance, an effect also NO-mediated as it is absent after Nomega-nitro-L-arginine methyl ester treatment and in endothelial nitric oxide synthase-deficient mice. These findings show that the rheological properties of plasma affect vessel diameter in the microcirculation leading to counterintuitive responses to the changes in blood and plasma viscosity. Application of these findings to haemorrhagic shock resuscitation leads to the concept of hyperosmotic-hyperviscous resuscitation as a modality for maintaining the recovery of microvascular function.

Effects of arterial hypotension on microvascular oxygen exchange in contracting skeletal muscle

In healthy animals under normotensive conditions (N), contracting skeletal muscle perfusion is regulated to maintain microvascular O2 pressures (Pmv[Formula: see text]) at levels commensurate with O2 demands. Hypovolemic hypotension (H) impairs muscle contractile function; we tested whether this condition would alter the matching of O2 delivery (Q̇o2) to O2 utilization (V̇o2), as determined by Pmv[Formula: see text] at the onset ofmuscle contractions. Pmv[Formula: see text] in the spinotrapezius muscles of seven female Sprague-Dawley rats (280 ± 6 g) was measured every 2 s across the transition from rest to 1-Hz twitch contractions. Measurements were made under N (mean arterial pressure, 97 ± 4 mmHg) and H (induced by arterial section; mean arterial pressure, 58 ± 3 mmHg, P < 0.05) conditions; Pmv[Formula: see text] profiles were modeled using a multicomponent exponential fitted with independent time delays. Hypotension reduced muscle blood flow at rest (24 ± 8 vs. 6 ± 1 ml−1·min−1·100 g−1 for N and H, respectively; P < 0.05) and during contractions (74 ± 20 vs. 22 ± 4 ml−1·min−1·100 g−1 for N and H, respectively; P < 0.05). H significantly decreased resting Pmv[Formula: see text] and steady-state contracting Pmv[Formula: see text](19.4 ± 2.4 vs. 8.7 ± 1.6 Torr for N and H, respectively, P < 0.05). At the onset of contractions, H reduced the time delay (11.8 ± 1.7 vs. 5.9 ± 0.9 s for N andH, respectively, P < 0.05) before the fall in Pmv[Formula: see text] and accelerated therate of Pmv[Formula: see text] decrease (time constant, 12.6 ± 1.4 vs. 7.3 ± 0.9 s for N and H, respectively, P < 0.05). Muscle V̇o2 was reduced by 71% at rest and 64% with contractions in H vs. N, and O2 extraction during H averaged 78% at rest and 94% during contractions vs. 51 and 78% in N. These results demonstrate that H constrains the increase of skeletal muscle Q̇o2 relative to that of V̇o2 at the onset of contractions,leading to a decreased Pmv[Formula: see text]. According to Fick's law, this scenario will decrease blood-myocyte O2 flux, thereby slowing V̇o2 kinetics and exacerbating the O2 deficit generated at exercise onset.

Inflammatory markers and hepatocyte growth factor in sustained hemodialysis hypotension

Hypotension is an important complication of hemodialysis. The pathogenesis of this complication remains unclear. The role of chronic inflammation in chronic dialysis-associated hypotension has not been investigated. A total of 38 dialysis patients with chronic hypotension were identified. Their demographic and biochemical data, inflammatory markers (high sensitivity C-reactive protein [hs-CRP] and interleukin-6 [IL-6]), hepatocyte growth factor (HGF), leptin, and adiponectin levels were measured and compared with those of another 87 nonhypotensive dialysis patients. No between-group differences in their clinical features, underlying renal disease were found. Levels of serum albumin, leptin, adiponectin, and HGF were similar between the two groups. The serum albumin levels were inversely correlated with hs-CRP and IL-6. Adiponectin was negatively correlated with hs-CRP and leptin. HGF showed a positive relation with hs-CRP. No association was found between adiponectin and HGF. Therefore, chronic inflammation is prevalent in the dialysis population, and serum HGF level is associated with inflammation but not with chronic dialysis hypotension.

The effects of acute fluid loading on plasma B-type natriuretic peptide levels in a septic shock patient

A 64-year-old female patient was admitted to a general intensive care unit with sustained hypotension resulting from severe sepsis. Her admission plasma B-type natriuretic peptide was elevated (407 pg/ml), and echocardiogram displayed normal ventricular dimensions and function. The right ventricular end-diastolic diameter increased with acute fluid loading, and this coincided with a parallel increase in B-type natriuretic peptide. Subsequent fluid depletion was accompanied by a reduction in both right ventricular end-diastolic diameter and B-type natriuretic peptide. The present case indicates that acute fluid loading may alter plasma B-type natriuretic peptide levels, and highlights the importance of taking the clinical context into account when interpreting these levels.

Caffeine attenuates early post-exercise hypotension in middle-aged subjects

BACKGROUND

Sustained hypotension after an acute dynamic exercise bout is due primarily to peripheral vasodilation. We tested the hypothesis that adenosine-mediated vasodilation contributes to hypotension after exercise, by determining the effect of blocking its actions with caffeine.

METHODS

Fourteen healthy middle-aged subjects (mean age = 51 +/- 3 years), cycled to peak effort on 2 study days, after a randomized double-blind intravenous infusion of caffeine (4 mg/kg) selective for adenosine receptor blockade, or vehicle. Both studies were performed after 72 h of caffeine abstinence.

RESULTS

Infusion achieved 52.0 +/- 6.1 mumol/L caffeine in plasma. Significant reductions in mean and diastolic blood pressure (BP) were elicited by prior exercise on the vehicle day (from 93 +/- 2 to 85 +/- 2 mm Hg v from 79 +/- 2 to 73 +/- 3 mm Hg, respectively; both P < .05), but not after caffeine infusion. Systolic and mean BP, 10 min after exercise, were higher on the caffeine than on the vehicle day (by 9 +/- 3 and 6 +/- 2 mm Hg, respectively; P < .05), as was heart rate (HR) (100 +/- 5 v 93 +/- 4 beats/min; P < .05).

CONCLUSIONS

These data suggest that endogenous adenosine contributes to early hypotension after exercise in healthy middle-aged subjects and underscore the importance of caffeine abstinence if BP or HR immediately after exercise is used to infer cardiovascular risk.