British Journal of Anaesthesia 1992; 69: 461^64
COMPARISON OF HYPERTONIC SALINE (5%), ISOTONIC
SALINE AND RINGER'S LACTATE SOLUTIONS FOR FLUID
PRELOADING BEFORE LUMBAR EXTRADURAL ANAESTHESIAf
P. VEROLI AND D. BENHAMOU
SUMMARY
We have compared the haemodynamic effects of
fluid preloading performed before lumbar extradural
anaesthesia with isotonic saline (NS), 5% hypertonic saline (HS) and Ringer's lactate (RL)
solutions in 30 ASA I patients undergoing minor
orthopaedic surgery, allocated randomly to the
three groups. All patients received an equal amount
of sodium (2 mmol kg~'J. After fluid preloading,
lumber extradural anaesthesia was performed (2 %
lignocaine 6 mg kg'1) and ephedrine was administered in order to maintain mean arterial pressure
(MAP) > 80% of its control value. Both volume and
duration of fluid preload were significantly less in
group HS (760 (SD 25) ml, 8.8 (SD 2.9) min) than
in the two other groups (NS: 903 (144) ml, 17.7
(3.3) min; RL: 932 (166) ml, 212 (6.0) min) (P <
0.05). The number of blocked segments and the
total amount of ephedrine administered were similar
in the three groups. Heart rate increased significantly in all groups immediately after the fluid
preload and remained increased until the end of the
study (90 min). MAP was not affected by any fluid
preload and its maximal decrease after lumbar
extradural anaesthesia was similar in all groups.
Infusion of 5% HS 2.3 ml kg'1 was tolerated well
and produced a significant (? < 0.05) but moderate
hypernatraemia lasting 90 min after the end of fluid
preloading. We conclude that HS may be useful
when rapid fluid preloading is desired, in situations
where excess free water administration is not
desired. (Br. J. Anaesth. 1992; 69: 461-464)
KEY WORDS
Anaesthetic techniques: extradural, fluid preloading. Fluid
balance: hypertonic saline, isotonic saline, Ringer's lactate.
Lumbar extradural anaesthesia may induce arterial
hypotension as a result of a sympathetic nerve block
[ 1 ]^_ Although haemodynamic effects induced by the
technique are usually tolerated well in healthy young
patients [2], prevention of hypotension is commonly
achieved using fluid preloading. Anaphylactic reactions may occur after the administration of colloids; this risk is rare, but may not be acceptable for
prophylaxis. Ringer's lactate solution (RL) is the
solution used most commonly for fluid preloading
[2], even though its sodium concentration (130 mmol
litre"1) is less than that in 0.9% isotonic sodium
chloride solution (NS) (155 mmol litre"1). Hypertonic saline solutions have been used effectively for
fluid resuscitation in haemorrhagic shock [3, 4],
during surgical treatment of aortic aneurysm [5] and
for postoperative fluid therapy after coronary artery
bypass grafting [6]. However, hypertonic saline (HS)
has not been evaluated for fluid preloading before
lumbar extradural anaesthesia.
The present study was undertaken to evaluate and
compare, in a randomized double-blind study, the
haemodynamic effects of fluid preloading performed
before lumbar extradural anaesthesia with hypertonic saline, Ringer's lactate and isotonic saline
solutions.
PATIENTS AND METHODS
After informed consent and local Ethics Committee
approval were obtained, we performed a prospective
double-blind study in 30 ASA physical status I adult
patients undergoing lower limb orthopaedic surgery
with tourniquet under lumbar extradural anaesthesia. After an overnight fast, all patients were
premedicated with hydroxyzine 2 mg kg"1 90 min
before surgery. Atropine was not administered. In
the anaesthetic room, before lumbar extradural
anaesthesia, a 16-gauge cannula was inserted into a
peripheral vein in an antecubital fossa. This cannula
was used for fluid preload in all patients, who were
allocated randomly to group RL: Ringer's lactate
solution 270 mosmol litre"1; group NS: 0.9 isotonic
sodium chloride 306 mosmol litre"1; group HS: 5 %
hypertonic saline 1700 mosmol litre"1. The 5% HS
solution was prepared by adding 250 ml of 20% HS
to distilled water 150 ml. In all groups, patients
received an equal amount of sodium (2 mmol kg"1)
(group RL 15 ml kg"1; group NS 13 ml kg"1; group
PHILLIPPE VEROLI*, M.D. ; DAN BENHAMOU, M.D. ; Department
-d'Anesthesie-Reanimarion—Universite" Paris=Sud^H6pital An~
toine Beclere, Clamart, France. Accepted for Publication: June 15,
1992.
•Present address, for correspondence: Departement d'Anesthesie—Reanimation, Hopital Saint-Camille, 2 Rue des Peres
Camillicns, 94366 Bry sur Marne Cedex, France.
tPresented in pan at the meeting of the American Society of
Anesthesiologists, San Francisco, October 1991.
BRITISH JOURNAL OF ANAESTHESIA
462
1
HS 2.3 ml kg" ). The time required for fluid preload
was noted in each patient. No more fluid was given
during the rest of the procedure. Immediately after
fluid preload, patients were transferred to the
operating theatre and were cared for by a physician
(P.V.) blinded to the fluid preload administered
previously. Lumbar extradural anaesthesia was performed at the L3-^l interspace with the patient in
lateral decubitus position. Lignocaine 2 % (6 mg
kg"1) with adrenaline 1:240000 was injected in
increments of 5 ml every 30 s through a Tuohy
needle, an extradural catheter was placed and the
patient was repositioned in the supine position. The
tourniquet was inflated and the surgical procedure
began when the level of the sensory block was
satisfactory. Patients breathed oxygen via a face
mask and SpOj was monitored continuously using a
pulse oximeter (Nellcor N 200). Heart rate (HR),
systolic, diastolic and mean arterial pressure (MAP)
were measured non-invasively before fluid preload
(control), after preload and every 2 min during the
following 90 min (Dinamap). A 3-mg bolus of
ephedrine was administered i.v. during the course of
lumbar extradural anaesthesia whenever MAP decreased to less than 80 % of its control value. Boluses
of midazolam 1 mg were administered as required
for sedation. The highest cutaneous level of the
sensory block was determined by cold sensation and
the patients were questioned concerning side effects.
Blood samples were obtained from a venous cannula
inserted in the opposite antecubital fossa, before and
after fluid preload and 30 and 90 min later. Plasma
concentrations of sodium, potassium, chlorine, bicarbonate and proteins, and PCV were measured.
Results are expressed as mean (SD). Statistical
analysis included ANOVA followed by an appropriate post-hoc test for quantitative data, chi-square
analysis with Yates' correction and the KruskalWallis test for non-parametric data. P < 0.05 was
considered as the minimum level of statistical
significance.
RESULTS
Patients were similar in physical characteristics
(table I) and initial values of HR and MAP. Volume
and duration of fluid preload were significantly less
in group HS than in the two other groups (table II).
Groups RL and NS were not significantly different
for volume and duration of fluid preloading. There
was no significant difference between groups in the
number of blocked segments and the total amount of
ephedrine administered (table I).
Fluid preloading was associated with a significant
increase in HR, whereas lumbar extradural anaesthesia induced a significant decrease in MAP and
a significant increase in HR (fig. 1). The maximal
decrease in MAP was similar in the three groups (RL
23 (13) %; NS 24 (15)%; HS 31 (10)%). Three
types of side effects were observed: thirst, headache
TABLE I. Patient data for the three groups: Ringer lactate solution
(RL), isotonic saline NS and 5% hypertonic saline (HS) (mean
(range or SD))
Sex
(M/F)
Age
(yr)
Weight
(kg)
Height
(cm)
4/6
7/3
4/6
44.3 (29-65)
38.7 (26-60)
34.4(18-56)
62.3(10.1)
71.2(10.7)
69.7 (10.7)
165 2(8 9)
174.2 (8.7)
171.3(9 5)
RL (n = 10)
NS (n = 10)
HS (n = 10)
TABLE II. Volume and duration of fluid preloading, number of
blocked segments (Blocked) and total amount of ephedrine administered in the three groups: Ringer's lactate solution (RL), isotonic
saline (NS) and 5% hypertonic saline (HS). * P < 0.05 vs RL and
NS
Volume (ml)
Duration (min)
Blocked (No.)
Ephedrine (mg)
RL
NS
932(166)
21 2 (6.0)
17(3)
12(20)
903(144)
17.7(3.3)
17(3)
13(15)
HS
160(25)*
8 8 (2.9)*
18(3)
9(9)
22
E |
E « 100
HS '
NS I
RL '
\
90
\
1 *
•
L
80
7 JS
i!
NS I
70 •
r
'
. - • ' "
RL i r"
-•{
i*
,.--'"
HS ' r""
x B
60
Before preload
After preload
Maximal change
FIG. 1. Changes in heart rate (open symbols) and mean arterial pressure (closed symbols) with each of the three solutes
tested: RL = Ringer lactate; NS = isotonic saline; HS = hypertonic saline. *P < 0.05 vs control value.
HYPERTONIC SALINE AND EXTRADURAL ANAESTHESIA
TABLE I I I . Heart rate (HR) and mean arterial pressure (MAP)
before and after fluid loading (FL) in the three groups. * P < 0.05 vs
control value
Group RL
HR (beat min"1)
Before FL
After FL
MAP (mm Hg)
Before FL
After FL
Group NS
69.4(14.3)
79.3(15.7)*
73.6(11.6)
80(15.15)*
92.6(15.8)
92.5(15.6)
97.2(14.5)
98.5(16.7)
Group HS
64.8(12.0)
73.1(13.4)*
98.9(9.9)
101.5(14.3)
and a warm sensation either generally or along the
infused vein (table III). The incidence of side effects
was not different between groups and the infusion
was not painful in any group.
Plasma concentration of sodium did not change
significantly in groups RL and NS. In group HS,
plasma concentration of sodium increased slightly
but significantly after fluid preload (2.2 (1.5)%) and
remained significantly increased at 30 and 90 min
after the end of preload. The greatest plasma
concentration of sodium observed in group HS was
147 mmol litre"1. A significant decrease in plasma
concentration of protein was observed immediately
after fluid preload in the three groups, but this was
evident until the end of the study only in the HS
group. PCV did not change with fluid preloading in
the RL group; in the NS group it decreased, but the
change was significant only in the first sample after
preload. In the HS group, this decrease was
significant until the 90-min sample. Other data are
reported in table IV.
463
DISCUSSION
Our study showed that with RL, NS and HS when
the same amount of sodium was infused during fluid
preloading, patients required similar amounts of
ephedrine after lumbar extradural anaesthesia in
order to maintain an adequate arterial pressure. HS
5 % contains 6.5 times more sodium than NS and the
same amount of sodium was given 2.5 times faster
than with RL or NS, as the volume to infuse was
smaller. In this study infusion of HS 2.3 ml kg"1 was
tolerated well and it produced a mild and transient
hypernatraemia.
The osmolality of the extracellular fluids depends
mainly on sodium concentration. The osmotic
pressure induced by the infusion of HS leads to an
almost instantaneous [7] outward movement of
intracellular water, which may explain the haemodilution observed immediately after fluid preload.
However, the serum protein concentration remained
significantly decreased at 30 and 90 min only in the
HS group. This implies that, for the same amount of
sodium infused, the extracellular fluid expansion is
more prolonged after an infusion of HS than after
RL or NS solution. However, this result remains to
be confirmed. The magnitude of the water transfer
can be calculated simply [8]. Although the infusion
of 5% HS 160 ml in an adult produces approximately a 2-litre increase in the extracellular
volume, HS-induced haemodynamic changes and
their duration cannot be related solely to water
movement. HS induces an intense and prolonged
venoconstriction [9, 10]. This reflex vascular effect
TABLE IV. Serum concentrations of electrolytes and protein and PCV before and after, and 30 min and 90 min after the end of fluid preloading (FP) with Ringer's lactate solution (RL), isotonic saline (NS) and 5% hypertonic saline (HS) (mean SD) [interquartile range}.
* P < 0.05; **P < 0.01; vs control value
Before FP
After FP
30 min
90 min
138.8 (2.4) [136-143]
140.4(1.1) [139-142]
140.7(2.1) [137-143]
138.2(2.8) [134-142]
140.9(1.5) [138-143]
143.7(1.7) [142-147]*
137.8 (3.2) [132-141]
139.8(1.4) [137-142]
142.4(2.3) [138-146]*
139(1.8) [136-141]
140.4(1.7) [138-142]
142.4(1.9) [140-146]*
Sodium
(mmol litre"1)
RL
NS
HS
Potassium
(mmol litre"1)
RL
NS
HS
3.7 (0.3) [3.1-1.2]
3.8 (0.3) [3.5-1.1]
3.8 (0.3) [3.3-1.2]
3.7 (0.5) [3.0-1.5]
4.0 (0.5) [3.5-1.7]
3.8 (0.4) [3.3-4.3]
3.8 (0.5) [3.4-1.7]
3.7 (0.2) [3.5-3.9]
3.8 (0.3) [3.3-4.3]
3.8 (0.7) [3.1-1.8]
3.9 (0.3) [3.6-1.4]
4.0 (0.4) [3.5-4.7]
102.7 (2.3) [99-106]
102.8 (2.2) [99-106]
104.6(1.4) [103-107]
103.2(2.9) [100-109]
105.2(2.0) [101-108]**
107.5(1.8) [105-110]**
103.4(2.7) [100-107]
104.6(2.2) [101-108]**
107.2(2.0) [105-112]**
103.4 (2.9) [100-109]
104.9(2.5) [102-110]**
107.1 (2.2) [103-110]*
26.8(1.9) [24-30]
25.9(2.8) [21-30]
25.9(2.6) [21-29]
26 (2.5) [23-30]
26 (2.4) [21-29]
26.5 (2.3) [23-30]
25.3(1.8) [23-28]
24.9(2.2) [21-28]
25.7 (2.6) [22-30]
25.9(2.5) [24-31]
25.9(3.2) [20-31]
26.1 (2.4) [24-29]
72rl (4.1) [66-78^
72.2 (3.6) [68-78]
73.4 (4.2) [64-80]
66.3 (2r7) [63-71]*
66.7 (3.7) [61-73]*
68.7(4.1) [61-72]**
71.8^5:8) [66-83]
72.6 (3.7) [68-78]
69.9 (4.5) [62-78]*
72.3<8.0M63-87]
72.8(3.1) [68-78]
69.0 (3.6) [64-74]*
37.8 (5.2) [32.5-17.4]
41.7 (2.6) [38.2-16.6]
42.4 (3.5) [34.2-15]
37.2 (5.7) [30.2-15.3]
39.2 (2.5) [36.9-44.3]**
39.7 (3.4) [33-12.9]**
39.3 (4.6) [33.6-15.2]
39.5 (2.7) [35.3-12.5]
41.2(3.4) [34.1-13.8]**
38.9 (5.0) [33.3-15.4]
39.7 (2.6) [35.6-12.6]
40.2 (3.4) [33.6-44]**
Chlorine
(mmol litre"1)
RL
NS
HS
Bicarbonates
(mmol litre"1)
RL
NS
HS
Proteins
(g litre"1)
RL
NS
HS
PCV (%)
RL
NS
HS
464
originates in the lung and is mediated by the vagus
nerve [11, 12]. Because our patients were undergoing
minor peripheral orthopaedic surgery, it was not
possible to measure changes in fluid compartments.
The clinical side effects observed during and after
infusion of HS were probably related to the hypertonicity of the solution. However, these side effects
were minimal in intensity and duration. In many
clinical studies, good tolerance was reported [3, 4,
13-15]. Infusions of 7.5 % HS 2400 mmol litre"1 up
to 400 ml have been reported to be safe [4].
Hypertonicity per se does not necessarily induce
phlebitis if the duration of infusion is limited [3].
However it is important to avoid extravasation.
The potential disadvantages of HS administration
include hypernatraemia, hyperchloraemia, hyperosmolality and hypokalaemia [16]. In our study,
patients who received HS had a significant increase
in plasma sodium concentration. However, this
increase was minimal and the maximal plasma
sodium concentration observed was 147 mmol litre"1.
Several studies [13—16] have demonstrated absence
of side effects of sodium concentrations of 160 mmol
litre"1. HS 5% (2.3 ml kg"1) is well tolerated and
may be useful when rapid fluid preloading is desired
and in situations where excess free water administration is not desired. However, the limits of HS use
remain to be denned.
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