Active clinical trials for "Hypotension"

Background: Poor spinal anaesthesia block is common and is difficult to manage; so a technique to minimize its incidence is advisable. Hypotension is the commonest problem with spinal anesthesia. Multiple trials to prevent or combat hypotension using positional changes, fluid therapy and the use of vasopressors were tried. However, the drug choice and mode of administration as either bolus or infusion is still a matter of debate. Objectives: To compare the outcome of spinal injection of hyperbaric bupivacaine and fentanyl separately to standard injection of mixed fentanyl with hyperbaric bupivacaine. Design: A randomized, controlled clinical trial. Setting: Single medical center from 5/2013 to 10/2014. Patients & Methods: 124 parturient scheduled for elective cesarean section (CS) were randomly allocated into two groups, each 62 parturient: Group M received spinal anesthesia using 10 mg bupivacaine 0.5% premixed with 25 µg fentanyl in the same syringe and Group S received 25 µg fentanyl in one syringe and 10 mg bupivacaine 0.5% without barbotage in a second syringe. Intravenous fluid co-load with 15 ml/kg warm lactated ringer solution was started as fast drip during, and continued after spinal anesthesia. Patients were monitored for hemodynamic parameters, time of sensory onset and height of maximum sensory block, lower limb motor blockade was scored using modified Bromage scale and the frequency of side effects.

This prospective, double-blinded, randomized, controlled study was undertaken to evaluate whether warming IV fluids (37 oC) resulted in lower incidence of hypotension, less ephedrine and transfusion requirement and lower fluid consumption than use of room-temperature fluids (22 oC) in cesarean delivery patients undergoing spinal anesthesia.

Electroencephalographic-based monitoring systems such as the bispectral index (BIS) may reduce anaesthetic overdose rates. The investigators hypothesised that goal-directed sevoflurane administration (guided by BIS monitoring) could reduce the sevoflurane plasma concentration (SPC) and intraoperative vasopressor doses during on-pump cardiac surgery in a prospective, controlled, sequential two-arm clinical study.

At our centre a conventional dose of 12 mg of hyperbaric bupivacaine in combination with a short acting opioid fentanyl (to increase block density) and a long acting opioid morphine (to provide post-operative pain relief ) is used for spinal anesthesia for cesarean section.However, larger doses of local anesthetic drug when used in caesarean section commonly cause low blood pressure and requires drugs (vasopressors) to treat it. In our study the investigators will standardize the doses of both opioids (fentanyl/morphine) and adjust the dose of local anesthetic (bupivacaine) based on the patients height and weight .One of the obvious challenges anesthesiologists face is providing adequate anesthesia to the patient whilst minimizing harmful side effects. Our primary concern is the low blood pressure as an effect of the spinal anesthetic as it is harmful to both mother and the baby. The investigators propose that the extent of surgical anesthetic block, which is dependent on height and weight in our adjusted dose group, will provide adequate anesthesia for surgery and minimise maternal low blood pressure.

Spinal anesthesia is widely used as the procedure of choice for cesarean delivery. In comparison to epidural anesthesia it is faster, easier to perform, patients are more comfortable, complication rates are lower, and it is more cost effective. Spinal anesthesia is an accepted technique in elective cesarean sections. However, hypotension, resulted from sympathectomy is a common problem, especially in pregnant women. Spinal block causes peripheral vasodilation and venous pooling, which may result in maternal hypotension. Maternal hypotension after spinal anesthesia for cesarean delivery, without prophylactic measures, has a very high incidence (80%-100%). Even though highly investigated, spinal induced hypotension remains a major concern, and it has been referred to as the "Holy Grail" of obstetric anesthesia. The detrimental effects of the spinal induced hypotension are maternal and fetal. Maternal effects are nausea, vomiting and dizziness. Hypotension results in reduced uterine and intervillous blood flow with potential fetal hypoxia and acidosis. Treatment and prevention of hypotension has been the subject of much investigation and controversy. Prophylactic measures include: 1) left lateral tilt, 2) fluid preload, 3) vasopressors,4) low dose spinal anesthesia. A 15° left lateral tilt is used routinely during cesarean section, to prevent aorto-caval compression, however it is not sufficient as a sole method. Left uterine displacement is achieved by tilting the operating table or by placing a wedge under the woman's hip. Aorto-caval compression also may increase the spread of spinal anesthesia. Among the non-pharmacological interventions studied to minimize the incidence of hypotension sitting the patient up for up to 7 min after CSE anesthesia for cesarean section reduced intraoperative ephedrine requirement without affecting the success of the spinal anesthetic. In contrast, sitting up for 9 min resulted in the need for rescue epidural anesthesia without additional benefit. Phenylephrine Treatment of vascular failure in shock, shock-like states, drug-induced hypotension or hypersensitivity; correction of paroxysmal supraventricular tachycardia; prolongation of spinal anesthesia; vasoconstriction in regional analgesia; maintenance of adequate level of BP during spinal and inhalation anesthesia. It has a number of important attributes for treating spinal hypotension: (i) as an alpha-adrenergic agonist, its mechanism of action directly addresses the decrease in systemic vascular resistance following spinal anesthesia;(ii) phenylephrine has a faster onset of action compared with ephedrine; (iii) ephedrine is associated with a five-fold increased risk of fetal acidosis; and (iv) ephedrine is more likely to cross the placenta and increase concentrations of lactate, glucose, and catecholamines in the fetal circulation compared with phenylephrine. However, phenylephrine used alone may be accompanied by maternal bradycardia and does not benefit from widespread clinical experience, as does ephedrine do. Thus, phenylephrine has not yet become popular, particularly for prophylactic use. Clinical experience suggests that phenylephrine may be useful in addition to ephedrine when the latter fails to correct hypotension. Ephedrine sulphate is a potent sympathomimetic that stimulates both α and β receptors and has clinical uses related to both actions. Its peripheral actions, which it owes in part to the release of norepinephrine, simulate responses that are obtained when adrenergic nerves are stimulated. These include an increase in blood pressure, stimulation of heart muscle, constriction of arterioles.

Ultrasound represents an attractive non-invasive method to assess hemodynamic status. Understanding dynamic changes in hemodynamics in situations such as hypovolemia, sepsis, and cardiogenic shock can potentially help improve patient care. However, the inter-rater reliability and accuracy of how various ultrasound measurements reflect dynamic changes in physiology remains incompletely understood. Overall our aims are to investigate the use of ultrasound in a controlled setting, specifically using lower body negative pressure (LBNP), which can simulate hypovolemia at varied levels in human volunteers. Aim 1: To determine the change in carotid blood flow (measured by velocity time integral, VTI) in subjects undergoing simulated hypovolemia at LBNP levels that precede vital sign changes. Hypothesis: Carotid VTI will demonstrate significant changes that precede vital sign changes in simulated hypovolemia. Aim 2: To compare transcranial color Doppler indices of cerebral blood flow with carotid blood flow, as assessed by VTI of the common carotid artery. Hypothesis: Changes in transcranial color Doppler indices of cerebral blood flow will be mirrored by changes in carotid blood flow, indicating carotid VTI is an adequate surrogate for measuring cerebral blood flow in variable states of central hypovolemia. However, if cerebral blood flow remains more constant than carotid blood flow throughout varying levels of hypovolemia, our assumption is that cerebral autoregulation alters the relationship between carotid and cerebral blood flow. The more complex procedure of Transcranial Doppler ultrasound (TCD) must be performed to obtain valid assessments of cerebral blood flow.

Hyperoxygenation for resuscitation of abnormal fetal heart rate tracings has been routine obstetric practice. However, there have not been any studies to support this practice. Recent literature have either found no associated benefit to intrapartum maternal oxygen administration, or in a number of studies demonstrated higher risk of neonatal complications. Despite these studies, the evidences have not been adequate to change the clinical practice because the majority of these studies either focused on biological differences rather than clinical outcomes data or were retrospective rather than randomized trials. Therefore, the investigators propose a large single center randomized clinical trial to determine the effects of maternal hyperoxygenation therapy for the treatment of fetal heart rate tracing abnormalities.

All over the world, spinal anesthesia is widely used in cesarean sections due to its superiority over general anesthesia. Due to reasons such as increased sensitivity to local anesthetics and increased intra-abdominal pressure in pregnant women, the frequency of hypotension increases by up to 70%. As a result of the blockage of sympathetic vasoconstrictor fibers originating from T1-L2 segments, loss of peripheral resistance, venous ponding occurs, and cardiac output decreases. Also, the level required for cesarean operation is T4 or T5, and the possibility of affecting the cardiac accelerator fibers, so bradycardia due to the increase in parasympathetic activity may deepen the hypotension. If postspinal hypotension is not managed correctly, it may lead to maternal and fetal complications. In addition to classical methods such as fluid loading and prophylactic vasoconstrictor application to prevent hypotension in pregnant women after spinal anesthesia, techniques such as wrapping the lower extremity, lifting, or applying both together have been in question. Passive leg raise application is an easy method that allows the blood collected in the lower part of the body to participate in the central circulation with the effect of gravity. An increase in venous return occurs with the passage of blood from the lower extremities to the thorax. Thus, it leads to an increase in stroke volume and an increase in cardiac output. In this study, we aimed to determine the effectiveness of passive leg raising in preventing or reducing the depth of hypotension after spinal anesthesia in pregnant women who underwent cesarean section under spinal anesthesia.

This is a randomized trial (1) investigating whether continuous invasive arterial blood pressure monitoring using an arterial catheter reduces the area under a mean arterial pressure (MAP) of 65 mmHg within the first 15 minutes of anesthetic induction compared to intermittent arterial blood pressure monitoring using oscillometry in patients having major surgery under general anesthesia; and (2) investigating the effect of continuous invasive arterial blood pressure monitoring using an arterial catheter on cardiac output, stroke volume, and heart rate within the first 15 minutes of anesthetic induction compared to intermittent blood pressure monitoring using upper-arm cuff oscillometry in patients having major surgery under general anesthesia.

This will be a randomized study aiming at investigating the combination of a norepinephrine infusion and colloid preloading versus the combination of a norepinephrine infusion and crystalloid co-loading for the prevention of maternal hypotension during elective cesarean section