Effect of crystalloid and colloid preloading on uteroplacental and maternal haemodynamic state during spinal anaesthesia for caesarean section

Abstract

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.

Manual displacement of the uterus during Caesarean section

“…The relative hypovolaemia caused by the combination of aortocaval compression and subarachnoid block may lead to placental insufficiency. The incidence of hypotension seems to be unexpectedly high despite preloading with crystalloids (47.4-83%) [1,2] or colloids (17-38%) [3,4] and the use of prophylactic vasoconstrictors (35-80%) [5].The universal practice of employing a 15°left lateral tilt using an obstetric wedge under the right hip [6] or tilting the table leftwards [7] might help to decrease the degree of aortocaval compression but does not guarantee its absence [8]. Maximum displacement of the uterus is best achieved by mechanical displacers.…”

Anaesthesia for insertion of bone‐anchored hearing aids in children: a 7‐year audit

“…Inappropriate use of these methods, because of the nature or site of the injuries, may lead to a failure of DVT prophylaxis. An effective alternative to anticoagulation may be vena caval interruption [14,15].…”

“…Other colloids have been studied in the context of obstetric spinal anaesthesia. Hydroxyethyl starch (HES) 6% has been shown to be more effective at maintaining maternal blood pressure than Ringer's lactate but neither solution can prevent it [14]. A preload of HES 6% combined with Ringer's lactate solution has been shown to be superior to both a gelatin/Ringer's lactate combination and HES alone [9].…”

“…Inappropriate use of these methods, because of the nature or site of the injuries, may lead to a failure of DVT prophylaxis. An effective alternative to anticoagulation may be vena caval interruption [14,15].There is increasing evidence that the use of low-dose unfractionated heparin and the newer low-molecularweight heparins (LMWH) in neurosurgical patients results in a clinically significant decrease in venous thromboembolism without inducing any significant increase of major bleeding [9,10,16,17]. However, anecdotal evidence suggests that most surgeons and anaesthetists intentionally avoid the use of heparin prophylaxis in this subgroup of patients.…”

Comparison of Hetastarch and Hartman’s Solution for Volume Preloading For Elective Caesarian Section- A Tertiary Care Teaching Centre Experience

“…J. Karinen et al (1995) found that incidence of maternal hypotension in the crystalloid group was 62% as compared to 38% in the colloid group. Colloid preloading has been suggested earlier (Twigly-1985) 66 and tried effectively by many others too.…”