Colloid Preload Research Articles

The Effects of Crystalloid and Colloid Preload on Cardiac Output in the Parturient Undergoing Planned Cesarean Delivery Under Spinal Anesthesia

Survey of Anesthesiology: August 2010 - Volume 54 - Issue 4 - p 173-174 doi: 10.1097/01.SA.0000377118.85841.c0

The Effects of Crystalloid and Colloid Preload on Cardiac Output in the Parturient Undergoing Planned Cesarean Delivery Under Spinal Anesthesia: A Randomized Trial

Hypotension after spinal anesthesia for cesarean delivery remains a major clinical problem. Fluid preloading regimens together with vasopressors have been used to reduce its incidence. Previous studies have used noninvasive arterial blood pressure measurement and vasopressor requirements to evaluate the effect of preload. We used a suprasternal Doppler flow technique to measure maternal cardiac output (CO) and corrected flow time (FTc, a measure of intravascular volume) before and after spinal anesthesia after 3 fluid preload regimens. We hypothesized that colloid solutions, compared with crystalloid, would produce the largest increase in CO and have the lowest incidence of hypotension. Sixty healthy term women scheduled for planned cesarean delivery under spinal anesthesia were recruited for this randomized, double-blind study. Baseline heart rate, systolic blood pressure (SBP), CO, and FTc were recorded in the left lateral tilt position. Patients were randomized to receive 1 of 3 fluid preload regimens given over 15 min: 1.5 L crystalloid (Hartman's solution), 0.5 L of 6% w/v hydroxyethyl starch (HES) solution (HES 0.5), or 1 L of 6% w/v HES solution (HES 1.0). Further measurements were made after fluid loading every 5 min for 30 min. After 30 min, spinal anesthesia was induced with hyperbaric bupivacaine 12.5 mg with fentanyl 15 microg and recordings were continued every 5 min for 20 min or until surgery started. The primary outcome, CO, was compared among groups. The incidence of hypotension (defined as a 20% reduction in SBP from the baseline), ephedrine use, and umbilical cord blood gases were also compared. Patient characteristics, heart rate, SBP, and cord gases were similar among groups. Although CO and FTc increased after preload in all groups (P < 0.005), this was only maintained with HES 1.0 after spinal anesthesia (P < 0.005). There were no differences among groups in the incidence of hypotension (70% vs 35% vs 65% for Hartman's solution, HES 0.5, and HES 1.0, respectively; P = 0.069) or mean ephedrine dose (10.4 vs 5.7 vs 9.7 mg; P = 0.26). Despite CO and FTc increases after fluid preload, particularly with HES 1.0 L, hypotension still occurred. The data suggest that CO increases after these preload regimens cannot compensate for reductions in arterial blood pressure after spinal anesthesia.

A Randomized Trial Comparing Colloid Preload to Coload During Spinal Anesthesia for Elective Cesarean Delivery

Hypotension after spinal anesthesia for cesarean delivery is common. Previous studies have demonstrated that a crystalloid fluid "coload" (rapid administration of a fluid bolus starting at the time of intrathecal injection) is superior to the conventional crystalloid preload (fluid administered before the intrathecal injection) for preventing hypotension. Colloid preload provides a sustained increase in central blood volume. We hypothesized that, in contrast to crystalloid, a colloid preload may be more effective than colloid coload for reducing the incidence of spinal anesthesia-induced hypotension. In this double-blind study, 178 patients were randomly assigned to receive a preload of 500 mL of hydroxyethyl starch over a period of 15-20 min before initiation of spinal anesthesia (n = 90) or an identical fluid bolus of hydroxyethyl starch starting at the time of identification of cerebrospinal fluid (n = 88). Vasopressors (ephedrine or phenylephrine) were administered if systolic arterial blood pressure decreased less than 80% of the baseline pressure and <100 mm Hg, or with smaller decreases in blood pressure if accompanied by nausea, vomiting, or dizziness. The primary outcome was the incidence of hypotension (defined as the administration of at least one dose of vasopressor). There was no significant difference between the groups in the incidence of hypotension (68% in preload group and 75% in coload group, 95% confidence interval of difference -6%-20%; P = 0.28), doses of ephedrine and phenylephrine, and number of vasopressor unit doses. The incidence of severe hypotension (systolic blood pressure <80 mm Hg) was 16% in the preload group and 22% in the coload group (P = 0.30). There were no differences in the incidence of nausea and/or vomiting, or neonatal outcome between the groups. There was no difference in the incidence of hypotension in women who received colloid administration before the initiation of spinal anesthesia compared with at the time of initiation of anesthesia. Both modalities are inefficient as single interventions to prevent hypotension.

Spinal Anaesthesia for Cesarean Section and Colloid Preload for Maintaining Arterial Pressure

Spinal Anaesthesia for Cesarean Section and Colloid Preload for Maintaining Arterial Pressure

The Effect of Colloid and Crystalloid Preloading on Thromboelastography Prior to Cesarean Delivery

The Effect of Colloid and Crystalloid Preloading on Thromboelastography Prior to Cesarean Delivery

Combined Use of Low-dose Bupivacaine, Colloid Preload and Wrapping of the Legs for Preventing Hypotension in Spinal Anaesthesia for Caesarean Section

We tested the hypothesis that using a combination of methods would result in a greater reduction in the incidence of hypotension due to spinal anaesthesia in caesarean sections compared with using each method on its own. A total of 120 patients were randomly allocated to the following four treatment groups: 10 mg bupivacaine 0.5% intrathecally plus 500 ml Ringer lactate solution (group B); 4 mg bupivacaine 0.5% plus 25 mug fentanyl plus 500 ml Ringer lactate solution (group F); 4 mg bupivacaine 0.5% plus 25 mug fentanyl intrathecally plus 500 ml Gelofusine intravenously (group G); and 4 mg bupivacaine 0.5% plus 25 mug fentanyl intrathecally plus 500 ml Gelofusine intravenously plus tight wrapping of the lower extremities with an Esmarch bandage (group E). The Esmarch bandage was only loosely applied in groups B, F and G. Hypotension was detected in 100% of the patients in group B compared with 70.0%, 46.7% and 23.3% of those in groups F, G and E, respectively. Hypotension was thus reduced by using a combination of several methods.

The sitting position in neurosurgery — Unresolved hemodynamic consequences!

ONTROVERSY continues to surround use of the sitting position for neurosurgical procedures. 1–3 The seated position, while presenting a number of challenges for the anesthesiologist, offers many surgical advantages for patients undergoing posterior fossa and cervical spine procedures. Specifically, the upright position improves operator orientation and surgical access to midline lesions in many posterior fossa cases. Gravitational drainage of venous blood from the surgical field and lowering of intracranial pressure increases technical ease and allows more rapid access to bleeding points. 4 An unobstructed view of the face allows motor responses to cranial nerve stimulation to be directly observed in the sitting position, and access to the anterior chest wall is facilitated in the event of cardiovascular collapse. Despite the many advantages offered from the surgical perspective, the sitting position presents unique physiological challenges for the anesthesiologist with the potential for serious complications. 1,5 Venous air embolism, with or without paradoxical air embolism, is a major concern in relation to the use of this position. 2,6 Hemodynamic instability with hypotension and potential compromise of cerebral and myocardial perfusion may occur. Reduction of inhaled volatile anesthetic agent and decreasing depth of anesthesia may predispose the seated patient to the risk of intraoperative awareness. Peripheral neuropathy 1 tension pneumocephalus, 7 and quadriplegia 1,2 are additional reported associated complications. The hemodynamic effects of anesthesia in the sitting position may be influenced by choice of ventilatory technique. Spontaneous ventilation with a volatile anesthetic agent in nitrous oxide/oxygen was popular in the 1960’s to provide signs of surgical encroachment on vital medullary and pontine structures. 8 The problems of cardiovascular instability and arterial hypotension associated with the upright position may be aggravated by the depressant effects of intravenous induction and volatile agents on myocardial contractility during general anesthesia and changes in venous return following intermittent positive pressure ventilation. 9 The volume of blood accumulating in the venous system may be influenced by patient factors - body mass index, intravascular volume status, pre-existing hypertension and mode of ventilation. As much as 1500 mL may be sequestered in the venous system of the lower limbs due to the effect of gravity 10 and increased diffusion through the capillary walls and venous dilatation associated with the use of volatile anesthetic agents. 11 Indicator dilution technique studies have confirmed a 14% redistribution of blood volume from the intra- to the extrathoracic compartment in anesthetized patients after a change from the supine to the sitting position. 12 Concomitant changes in arterial pressure and stroke volume index were thus attributed to alterations in cardiac preload. A number of techniques have been advocated to attenuate the hemodynamic effects of patient placement in the sitting position. Colloid preloading (10 mL·kg –1 ) 30 min before starting general anesthesia was reported to prevent decreases in systolic and central venous pressures during sitting patient positioning without adverse effects. 13 Compensatory mechanisms, perhaps mediated by the renin-angiotensin-aldosterone system or the sympathetic nervous system, may be operative in the awake or anesthetized state to attenuate adverse hemodynamic changes associated with the sitting position. Wrapping of the legs, application of anti-gravity suits and positioning of the knees at right heart level may all have potential benefits.

Prediction of hypotension during spinal anesthesia for cesarean section and its relation to the effect of crystalloid or colloid preload

If parturients prone to develop caval compression in the supine position were identified before delivery, this might be a method of predicting hypotension during caesarean section under spinal anesthesia. Colloid preloading is superior to crystalloid in reducing the risk for spinal anesthetic-induced hypotension. It is postulated that parturients preoperatively susceptible to the supine position would benefit the most from colloid preloading. Fifty-five healthy parturients scheduled for elective cesarean section under spinal anesthesia were preoperatively investigated with a supine stress test with measurement of maternal heart rate, blood pressure, right uterine artery pulsatility index and symptoms in the left lateral and supine positions. They were then randomized to receive a colloid or crystalloid preload before anesthesia. The stress test was positive, indicating a reduced tolerance to the supine position, in 36%. The sensitivity and specificity of the stress test for clinically significant hypotension (symptomatic hypotension) for patients randomized to the crystalloid group (n=25) were 69 and 92% respectively. Patients with a positive stress test receiving a crystalloid preload showed a higher frequency of hypotension compared to all other groups, 90% vs. 33%, (P=0.003) and also a greater need for ephedrine, mean dose (SD): 20.0 (9.7) vs. 8.4 (9.0) mg (P=0.002). Pregnant women with a positive preoperative supine stress test constitute a subset at increased risk for clinically significant hypotension during cesarean delivery under spinal anesthesia. These women seem more likely to benefit from prophylactic colloid solution than women with a negative stress test.

Colloid vs. Crystalloid Preloading to Prevent Maternal Hypotension During Spinal Anesthesia for Elective Cesarean Section

Colloid vs. Crystalloid Preloading to Prevent Maternal Hypotension During Spinal Anesthesia for Elective Cesarean Section

Colloid vs. Crystalloid Preloading to Prevent Maternal Hypotension during Spinal Anesthesia for Elective Cesarean Section

Colloid vs. Crystalloid Preloading to Prevent Maternal Hypotension during Spinal Anesthesia for Elective Cesarean Section

Regional anaesthesia for caesarean section

In the UK, over 80% of caesarean sections are performed under regional anaesthesia. There are four categories of surgery depending on the degree of urgency. Informed consent is vital and must be documented. All women should receive aspiration prophylaxis premedication (H 2-antagonist, metoclopramide, and within 30 minutes of surgery, a non-particulate antacid). Regional anaesthesia should be established in theatre. In emergencies, some authorities advocate topping up indwelling epidural catheters before transfer to theatre. Standards for monitoring and anaesthetic assistance are the same for obstetric and general surgery. Intravenous access must always be obtained before regional anaesthesia. Fetal heart rate monitoring should be continued during institution of the block and until the start of surgery. Supplemental oxygen is no longer considered mandatory for the mother in the absence of fetal distress. Institution of blockade must be performed in an aseptic manner. Sterile gloves are essential and face masks and gowns are highly recommended. Hypotension should be minimized by avoiding aortocaval compression, vasopressors (prophylactically/therapeutically) and colloid preloading. Single-shot spinal (SSS), combined spinal-epidural (CSE), and epidural may be used. SSS is simple and quick to perform. CSE is associated with the lowest rate of conversion to general anaesthesia and greater haemodynamic stability than SSS. Epidural anaesthesia has the highest failure rate, but if an epidural has been placed for labour, most practitioners would advocate its use rather than resorting to intrathecal anaesthesia. A block to touch from S1 to T5 or above is essential. All patients should be assessed postoperatively.

Prevention of Hypotension with Crystalloid Versus Colloid During Spinal or Combined Spinal-Epidural Anesthesia for Cesarean Delivery

Background: The prevention of hypotension continues to be one of major challenges in spinal anesthesia (SA) for cesarean delivery. And prehydration is widely performed to prevent hypotension. However, some controversy exists over the types of fluid used for prehydration. Therefore, we investigated the effects of crystalloid versus colloid preload on the incidences of hypotension, and the notion that minimal local anesthetic used in combined spinal-epidural anesthesia (CSEA) could further decrease the incidence of hypotension after colloid preloading. Methods: One hundred and fifty parturients were randomly allocated into three groups: CR (crystalloid)-SA, CO (colloid)-SA, and CO-CSEA according to the types of preload and anesthesia. In the CR-SA group, 1,000-1,500 ml of crystalloid was administered under spinal anesthesia. In the CO-SA and CO-CSEA groups, 500 ml of colloid followed by 500-1,000 ml of crystalloid under SA and CSEA was administered, respectively. Bupivacaine 9 mg with opioids was used for SA, and bupivacaine 6 mg with opioids and epidural top-up with 0.25% bupivacaine 10 ml for CSEA. Incidences of hypotension, nausea and vomiting were recorded until delivery. Results: Colloid preload reduced the incidence of hypotension (18% vs 44%, P = 0.005), and side effects (2% vs 20%, P = 0.005) compared to crystalloid in SA. However, lowering local anesthetic using CSEA (hypotension 20%, side effects 4%) did not further decrease the incidences of hypotension and side effects when using colloid. Conclusions: Colloid is a better fluid for prehydration in cesarean section under spinal anesthesia. 18-20% is considered a minimum incidence of hypotension.

▪ Effects of Crystalloid and Colloid Preload on Blood Volume in the Parturient Undergoing Spinal Anesthesia for Elective Cesarean Section

▪ Effects of Crystalloid and Colloid Preload on Blood Volume in the Parturient Undergoing Spinal Anesthesia for Elective Cesarean Section

Effect of Crystalloid and Colloid Preloading on Uteroplacental and Maternal Haemodynamic State During Spinal Anaesthesia for Caesarean Section

We have studied the effects of crystalloid 1 litre (lactated Ringer's) or colloid 0.5 litre (hydroxyethyl starch) preloading in 26 healthy parturients undergoing elective Caesarean section under spinal anaesthesia. Maternal placental uterine artery circulation was measured using a pulsed colour Doppler technique with simultaneous measurement of maternal haemodynamics. A high incidence of maternal hypotension was observed during spinal anaesthesia in the crystalloid group (62%) but the incidence was lower in the colloid group (38%). Central venous pressure was increased significantly in both groups after preload but decreased shortly after induction of spinal anaesthesia to baseline values. The mean pulsatility index (PI) in the uterine arteries did not change during preload or spinal block. A surprising finding was the widespread variation and some high values for the uterine artery PI after spinal anaesthesia. These individual increases in PI were transient and always returned to baseline values within 2 min. These results suggest that preloading with either solution is ineffective in preventing maternal hypotension and that changes in maternal heart rate, systolic arterial pressure and central venous pressure during spinal anaesthesia were not associated with rapid individual increases in uteroplacental vascular resistance. These changes seemed not to have any major effect, however, on the clinical condition of the newborn, as assessed by Apgar scores and umbilical artery pH values.

Uteroplacental and fetal haemodynamics and cardiac function of the fetus and newborn after crystalloid and colloid preloading for extradural Caesarean section anaesthesia

We have studied the effects of randomized preloading with either a crystalloid (lactated Ringer's) 15 ml kg-1 or colloid (hydroxyethyl starch) 7.5 ml kg-1 solution in 20 parturients undergoing elective Caesarean section under extradural anaesthesia, on blood flow in maternal placental and non-placental uterine and placental arcuate arteries and in fetal umbilical, renal and middle cerebral arteries, using a pulsed colour Doppler technique. Simultaneously, fetal and neonatal myocardial function were investigated by pulsed Doppler and M-mode echocardiography. We found no changes in maternal or fetal blood velocity waveform indices after crystalloid preloading, but the pulsatility index of the maternal non-placental uterine artery increased significantly after colloid preloading. Fetal heart rate decreased after preloading with crystalloid solution. There were no differences in fetal or neonatal myocardial function between the groups, and the outcome of the newborn infants were uneventful in all cases. These results suggest that preloading with either a crystalloid or colloid solution may lead to different uterine and fetal haemodynamics but these solutions had only minimal effects on fetal and neonatal myocardial performance and no effect on the clinical condition of newborns in uncomplicated pregnancies.