Interaction between the lateral preoptic area and the subfornical organ in the control of water ingestion caused by cellular dehydration, hypotension, hypovolemia, and deprivation

Water intake was studied in albino rats with lesions in the lateral preoptic area, in the subfornical organ, and in both the lateral preoptic area and the subfornical organ. Drinking was induced by cellular dehydration, hypovolemia, hypotension (isoproterenol or caval ligation), and water deprivation. The animals with lesions in both areas showed a significant reduction in their water intake in response to cellular dehydration. Drinking due to extracellular dehydration was reduced in the animals that received only subfornical organ lesions, and was reduced even further in the animals with both areas ablated. The lesions in the subfornical organ were sufficient to reduce the thirst induced by caval ligation. The lesions in both areas inhibit water intake induced by caval ligation. Water intake induced by deprivation was reduced when both areas were destroyed. These findings demonstrate that both the lateral preoptic area and the subfornical organ are necessary for normal drinking in response to cellular dehydration, hypovolemia, and hypotension. There is further evidence that the lateral preoptic area and subfornical organ interact in the control of water intake induced by a variety of thirst challenges.

Tepoxalin on renal function and liver enzymes in cats exposed to hypotension with isoflurane

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Orthognathic surgery with or without induced hypotension

This study involved a retrospective evaluation of patients subjected to surgery for dentofacial deformities treated without induced controlled hypotension (group I, n = 50) and a prospective evaluation of patients who were subjected to surgery under hypotensive general anaesthesia (group II, n = 50). No statistical differences were found between the study groups with regard to the duration of surgery. However, there were statistically significant differences in the need for blood transfusion and the occurrence of bradycardia during the maxillary down-fracture. Hypotensive anaesthesia decreased the need for a blood transfusion and the occurrence of bradycardia, and is therefore considered highly beneficial for patients undergoing orthognathic surgery.

Type 2 Diabetes Elicits Lower Nitric Oxide, Bradykinin Concentration and Kallikrein Activity Together with Higher DesArg(9)-BK and Reduced Post-Exercise Hypotension Compared to Non-Diabetic Condition

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Prevention of Intradialytic Hypotension in Patients with Acute Kidney Injury Submitted to Sustained Low-Efficiency Dialysis

Objectives: This study evaluated the effects of a protocol aiming to reduce hypotension in acute kidney injury (AKI) patients submitted to sustained low-efficiency dialysis (SLED). Methods: Patients were randomly assigned to two SLED prescriptions-control group, dialysate temperature was 37.0 degrees C with a fixed sodium concentration [138 mEq/L] and ultrafiltration (UF) rate; and profiling group, dialysate temperature was 35.5 degrees C with a variable sodium concentration [150-138 mEq/L] and UF rate. Results: Sixty-two SLED sessions were evaluated (34 in profiling and 28 in control). Patients (n = 31) were similar in terms of gender, age, and Sequential Organ Failure Assessment (SOFA) score. Dialysis time, dialysis dose, and post-dialysis serum sodium were similar in both groups. The profiling group had significantly less hypotension episodes (23% vs. 57% in control, p = 0.009) and achieved higher UF volume (2.23 +/- 1.25 L vs. 1.59 +/- 1.03 L in control, p = 0.04) when compared with control group. Conclusions: SLED protocol with modulation of dialysate temperature, sodium, and UF profiling showed similar efficacy but less intradialytic hypotension when compared with a standard SLED prescription.

Effect of 12 weeks of resistance exercise on post-exercise hypotension in stage 1 hypertensive individuals

Post-exercise hypotension (PEH), the reduction of blood pressure (BP) after a single bout of exercise, is of great clinical relevance. As the magnitude of this phenomenon seems to be dependent on pre-exercise BP values and chronic exercise training in hypertensive individuals leads to BP reduction; PEH could be attenuated in this context. Therefore, the aim of the present study was to investigate whether PEH remains constant after resistance exercise training. Fifteen hypertensive individuals (46 +/- 8 years; 88 +/- 16 kg; 30 +/- 6% body fat; 150 +/- 13/93 +/- 5mm Hg systolic/diastolic BP, SBP/DBP) were withdrawn from medication and performed 12 weeks of moderate-intensity resistance training. Parameters of cardiovascular function were evaluated before and after the training period. Before the training program, hypertensive volunteers showed significant PEH. After an acute moderate-intensity resistance exercise session with three sets of 12 repetitions (60% of one repetition maximum) and a total of seven exercises, BP was reduced post-exercise (45-60 min) by an average of aproximately -22mm Hg for SBP, -8mm Hg for DBP and -13 mm Hg for mean arterial pressure (P<0.05). However, this acute hypotensive effect did not occur after the 12 weeks of training (P>0.05). In conclusion, our data demonstrate that PEH, following an acute exercise session, can indeed be attenuated after 12 weeks of training in hypertensive stage 1 patients not using antihypertensive medication. Journal of Human Hypertension (2012) 26, 533-539; doi:10.1038/jhh.2011.67; published online 7 July 2011

Muscle ischaemia in patients with orthostatic hypotension assessed by velocity recovery cycles

Patients with orthostatic hypotension may experience neck pain radiating to the occipital region of the skull and the shoulders while standing (so-called coat-hanger ache). This study assessed muscle membrane potential in the trapezius muscle of patients with orthostatic hypotension and healthy subjects during head-up tilt (HUT), by measuring velocity recovery cycles (VRCs) of muscle action potentials as an indicator of muscle membrane potential.

Hypotension during fluid-restricted abdominal surgery: effects of norepinephrine treatment on regional and microcirculatory blood flow in the intestinal tract

Vasopressors, such as norepinephrine, are frequently used to treat perioperative hypotension. Increasing perfusion pressure with norepinephrine may increase blood flow in regions at risk. However, the resulting vasoconstriction could deteriorate microcirculatory blood flow in the intestinal tract and kidneys. This animal study was designed to investigate the effects of treating perioperative hypotension with norepinephrine during laparotomy with low fluid volume replacement.

Terlipressin as an adjunct vasopressor in refractory hypotension after tricyclic antidepressant intoxication

AIM OF STUDY: To report the management of cardiovascular failure refractory to standard catecholamine therapy with terlipressin in a patient with tricyclic antidepressant (TCA) intoxication. CASE REPORT: A 41-year-old woman, with suicidal ingestion of 11.25 g amitriptyline and 1500 mg diclofenac, was admitted to the emergency department. After 30 min in ventricular fibrillation, with ongoing CPR, she regained a potentially perfusing rhythm, but with hypotension refractory to standard catecholamine therapy with adrenaline, 2 microg/kg/min (norepinephrine); adrenaline, 1 microg/kg/min (epinephrine) until 55 min after admission. An injection of 1 mg terlipressin restored mean arterial blood pressure >65 mmHg within 10 min. Ten hours after admission to the intensive care unit, catecholamine support could be withdrawn because of a stable haemodynamic state. Within 7 days, all organ function recovered, and the patient regained full neurological function. CONCLUSIONS: Successful management of cardiovascular failure with terlipressin after TCA intoxication refractory to catecholamines suggests a potential role for terlipressin as an adjunct vasopressor in severely hypotensive patients.

Hypovolemia contributes to the pathogenesis of orthostatic hypotension in patients with diabetes mellitus

PURPOSE: To investigate whether body sodium content and blood volume contribute to the pathogenesis of orthostatic hypotension in patients with diabetes mellitus. SUBJECTS AND METHODS: Exchangeable sodium, plasma and blood volumes, and catecholamine, renin, and aldosterone levels were assessed in 10 patients with Type II diabetes mellitus who had orthostatic hypotension and control groups of 40 diabetic patients without orthostatic hypotension and 40 normal subjects of similar age and sex. In subgroups, clinical tests of autonomic function and cardiovascular reactivity to norepinephrine and angiotensin II infusions were performed. RESULTS: In diabetic patients with orthostatic hypotension, mean (+/- SD) supine blood pressure was 165/98 +/- 27/12 mm Hg (P <0.05 compared with other groups) and mean upright blood pressure was 90/60 +/- 38/18 mm Hg. Compared with controls, diabetic patients with orthostatic hypotension had a 10% lower blood volume. They also had less exchangeable sodium than patients with diabetes who did not have orthostatic hypotension (P <0.01). Compared with both groups of controls, diabetic patients with orthostatic hypotension had decreased 24-hour urinary norepinephrine excretion and a reduced diastolic blood pressure response to handgrip (P <0.05). Moreover, they displayed reduced products of exchangeable sodium or blood volume and sympathetic function indexes. Cardiovascular pressor reactivity to norepinephrine was enhanced (P <0.01) and beat-to-beat variation decreased (P <0.01) in both groups of diabetic patients. Microvascular complications were more prevalent in the diabetic patients with orthostatic hypotension (90% vs 35%). CONCLUSIONS: Patients who have Type II diabetes mellitus and orthostatic hypotension are hypovolemic and have sympathoadrenal insufficiency; both factors contribute to the pathogenesis of orthostatic hypotension.

[The treatment of orthostatic hypotension with metoclopramide]

The dopamine receptor antagonist metoclopramide (paspertin, primpéran, gastrosil, meclopran, gastro-timelets), used as monotherapy or in combination with an inhibitor of the cyclooxygenase enzyme, affords good results in orthostatic hypotension due to insufficiency of the sympathetic nervous system. The mechanism of action in these cases is unclear but is assumed to be elevation of vascular tone in the splanchnic vessels. A case is discussed which documents the effectiveness of metoclopramide therapy in orthostatic hypotension, even in absence of signs of autonomic dysfunction.

Contrast-enhanced MR myelography in spontaneous intracranial hypotension: description of an artefact imitating CSF leakage

In contrast-enhanced (CE) MR myelography, hyperintense signal outside the intrathecal space in T1-weighted sequences with spectral presaturation inversion recovery (SPIR) is usually considered to be due to CSF leakage. We retrospectively investigated a hyperintense signal at the apex of the lung appearing in this sequence in patients with SIH (n = 5), CSF rhinorrhoea (n = 2), lumbar spine surgery (n = 1) and in control subjects (n = 6). Intrathecal application of contrast agent was performed in all patients before MR examination, but not in the control group. The reproducible signal increase was investigated with other fat suppression techniques and MR spectroscopy. All patients and controls showed strongly hyperintense signal at the apex of the lungs imitating CSF leakage into paraspinal tissue. This signal increase was identified as an artefact, caused by spectroscopically proven shift and broadening of water and lipid resonances (1-2 ppm) in this anatomical region. Only patients with SIH showed additional focal enhancement along the spinal nerve roots and/or in the spinal epidural space. In conclusion CE MR myelography with spectral selective fat suppression shows a reproducible cervicothoracic artefact, imitating CSF leakage. Selective water excitation technique as well as periradicular and epidural contrast collections may be helpful to discriminate between real pathological findings and artefacts.

Orthostatic hypotension in Parkinson's disease: association with cognitive decline?

BACKGROUND Orthostatic hypotension is common in Lewy body disorders and may be related to disease progression and the spread of Lewy body pathology. We therefore hypothesize that PD patients with orthostatic hypotension (OH) have a different cognitive profile compared to PD patients without OH. METHODS This cross-sectional study included 175 PD patients. Blood pressure (BP) was measured with a validated digital blood pressure monitor and patients with a systolic BP drop of > or =20 mmHg or a systolic pressure of <90 mm Hg after standing were considered to have OH. Cognition was assessed using MMSE extended by a selection of computerized cognitive tests focusing on reaction time, sustained attention, working memory and episodic verbal and visual memory. RESULTS Eighty-seven (49.7%) of the PD patients had OH. These patients were significantly more impaired in sustained attention and visual episodic memory compared to PD patients without OH. CONCLUSION We conclude that there are differences in the neuropsychological performance of patients with PD and OH, supporting the hypothesis that OH might be a marker for disease progression and cognitive decline in PD.

Re-thinking resuscitation: leaving blood pressure cosmetics behind and moving forward to permissive hypotension and a tissue perfusion-based approach

Definitions of shock and resuscitation endpoints traditionally focus on blood pressures and cardiac output. This carries a high risk of overemphasizing systemic hemodynamics at the cost of tissue perfusion. In line with novel shock definitions and evidence of the lack of a correlation between macro- and microcirculation in shock, we recommend that macrocirculatory resuscitation endpoints, particularly arterial and central venous pressure as well as cardiac output, be reconsidered. In this viewpoint article, we propose a three-step approach of resuscitation endpoints in shock of all origins. This approach targets only a minimum individual and context-sensitive mean arterial blood pressure (for example, 45 to 50 mm Hg) to preserve heart and brain perfusion. Further resuscitation is exclusively guided by endpoints of tissue perfusion irrespectively of the presence of arterial hypotension ('permissive hypotension'). Finally, optimization of individual tissue (for example, renal) perfusion is targeted. Prospective clinical studies are necessary to confirm the postulated benefits of targeting these resuscitation endpoints.