Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 9  |  Issue : 2  |  Page : 250-255

Comparison between colloid preload, coload, and no load in the prevention of spinal anesthesia-induced hypotension in patients undergoing inguinal hernia repair


Department of Anesthesia and Intensive Care, Ain Shams University, Cairo, Egypt

Date of Submission22-Nov-2015
Date of Acceptance23-Feb-2016
Date of Web Publication11-May-2016

Correspondence Address:
Heba A Labib
Department of Anesthesia and Intensive Care, Ain Shams University, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-7934.182266

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  Abstract 

Background and objective
The aim of this study was to know whether colloid fluid administration (either preloading or coloading) can decrease the incidence of hypotension secondary to spinal anesthesia in an elderly population undergoing inguinal hernia repair without mesh.
Patients and methods
After obtaining institutional ethical committee's approval and patients' informed consent, 84 patients (aged 61-89 years) scheduled for elective inguinal hernia repair were enrolled in this prospective, randomized study. We compared the incidence of hypotension and ephedrine requirement after spinal anesthesia between three groups: group P (n = 28), in which patients were preloaded with 500 ml of 6% hydroxyethyl starch solution (130/0.4), group C (n = 28), in which patients were coloaded with 6% hydroxyethyl starch solution during spinal anesthesia, and group N (n = 28), in which patients were not given any fluid.
Results
The incidence of hypotension and the mean dose of ephedrine were not significantly different between the three groups.
Conclusion
We concluded that, in elderly patients undergoing inguinal hernia repair, withholding fluid loading (whether preloading or coloading) did not increase the incidence of spinal anesthesia-induced hypotension and did not affect the dose of ephedrine required to correct hypotension, if occurred.

Keywords: colloid preloading, coloading, elderly, spinal anesthesia


How to cite this article:
Elewa GM, Labib HA, Samir GM. Comparison between colloid preload, coload, and no load in the prevention of spinal anesthesia-induced hypotension in patients undergoing inguinal hernia repair. Ain-Shams J Anaesthesiol 2016;9:250-5

How to cite this URL:
Elewa GM, Labib HA, Samir GM. Comparison between colloid preload, coload, and no load in the prevention of spinal anesthesia-induced hypotension in patients undergoing inguinal hernia repair. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2021 May 9];9:250-5. Available from: http://www.asja.eg.net/text.asp?2016/9/2/250/182266


  Introduction Top


From 1960s, when two reports by Wollman and Marx [1] and Marx et al. [2] advocated prehydration by 1 l of crystalloid for the prevention of spinal anesthesia-induced hypotension of women undergoing cesarean section, routine prehydration of all patients with 10-15 ml/kg crystalloid before spinal anesthesia has gained widespread acceptance. But nowadays, this practice is being challenged. Jackson et al. [3] found no disadvantage in giving only 200 ml compared with 1 l of crystalloid prehydration in the incidence and severity of hypotension after spinal anesthesia in young women undergoing elective cesarean section, and they recommended avoiding prehydration as a routine measure.

Researches support a decreased use of crystalloid prehydration and ephedrine and an increased use of cohydration by colloids [4]. Colloids remain for a longer period within the intravascular space, and colloid preload provides a sustained increase in the central venous blood volume and cardiac output [5]. However, most studies [1-6] on spinal anesthesia-induced hypotension have been conducted on a homogeneous population of young women in obstetric units [6]. Hence, their conclusions should be applied with caution to other patient populations.

Not enough attention has been paid on the effect of the timing of hydration on spinal anesthesia-induced hypotension in the elderly, despite their greater vulnerability to decompensation from rapid fluid shifts, hemodilution, and hemodynamic instability [7].

Therefore, our objective in this study was to know whether colloid fluid administration (either preloading or coloading) could decrease the incidence of hypotension secondary to spinal anesthesia in elderly population. Elderly was defined as patients with age more than 60 years old according to the Health Statistics and Information Systems [8].


  Patients and methods Top


This study was carried out in Ain Shams University Hospitals between June 2013 and March 2015 after obtaining approval from the institutional ethics committee and informed written consent from the patients. A total of 84 patients (aged 61-89 years) scheduled for inguinal hernia repair without mesh were enrolled in this prospective, randomized study. Randomization was done using computer-generated random number tables with closed/sealed envelopes. Exclusion criteria were ASA grade III or higher, age less than 61 years, known chronic hypertension, congestive cardiac failure, or renal dysfunction.

All patients were fasted for 8 h for food but clear fluids were stopped for only 4 h, and no intravenous fluids were given until their arrival in the induction room, after which an 18-G cannula was inserted in a forearm vein. Patients were randomized into three equal groups: group P (n = 28), in which patients were given 500 ml of 6% hydroxyethyl starch solution (HES) (130/0.4) 15-20 min before giving spinal anesthesia; group C (n = 28), in which patients were coloaded with 6% HES during spinal anesthesia; and group N (n = 28), in which patients were given no fluids.

Spinal anesthesia was administered in the lateral position under complete aseptic conditions, with the surgery side-dependent, using a 25-G spinal needle at the L2-L3 or L3-L4 intervertebral space. All patients received 2.5 ml of hyperbaric bupivacaine 0.5%. The highest sensory level was documented after the intrathecal injection using a cold bag in a dermatomal distribution. Patients remained in the side position for the ensuing 15-20 min. Then, the patients were either turned to the supine position or to the lateral position so that the surgery side was up.

Baseline arterial blood pressure (systolic, diastolic, and mean) was taken as the mean of three preoperative readings, using an automated oscillotonometer. Noninvasive blood pressure was recorded at 1-min intervals for 10 min, and then at 5 min intervals for 50 min. Other standard monitoring were applied (ECG, temperature, and pulse oximetry).

Hypotension was defined as a decrease in mean arterial pressure (MAP) of 25% from baseline [9] or an absolute systolic blood pressure (SBP) value of less than 90 mmHg [10]. Hypotension was treated with ephedrine in 3 mg increments, repeated every 3 min if required. Incidence of hypotension, number of patients who required ephedrine, mean amount of ephedrine was defined, and possible side effects were also recorded as, all ephedrine administered to that group/number of patients actually in need of it.

The primary outcome of the study was comparing the incidence of hypotension in the studied groups. Secondary outcomes included number of patients who were given ephedrine, amount of ephedrine administered, and other possible side effects in each group.

Statistical analysis

Sample size calculation was performed using PASS 11. On the basis of the data from previous studies [8, 11, 12], sample size of 25 patients per group was expected to achieve 80% power to detect 40% decrease in the incidence of hypotension with 0.05000 significance level. To compensate for possible dropouts, 28 patients per group were included.

Data were analyzed using the SPSS 21.0 for Windows (SPSS Inc., Chicago, Illinois, USA). Analysis of variance was used to compare the three groups for quantitative parametric data; the post-hoc Scheffe test was carried out whenever a significant difference was detected; the Kruskal-Wallis test was used for quantitative nonparametric data, with application of the Mann-Whitney U-test post-hoc, whenever a significant difference was detected. The c2 -test was used for the comparison of qualitative data, with application of Fisher's exact test when appropriate. Continuous parametric data were expressed as mean ± SD, nonparametric data as median (interquartile range), and categorical data were presented as number of patients. P-values of less than 0.05 were considered statistically significant.


  Results Top


Although 84 patients were initially enrolled, two patients were subsequently excluded from the study: one patient from the preload (P) group as spinal anesthesia was inadequate so that general anesthesia had to be applied; and the other patient from the coload (C) group as the patient was irritable and needed sedation.

Thus, a total of 82 patients were studied in three groups: group P (n = 27), group C (n = 27), and group N (n = 28). There was no statistically significant difference between the three groups as regards age, sex, height, weight, baseline SBP, diastolic, and MAP, baseline heart rate, highest sensory level, and the proportion of patients with a sensory level of T7 or higher [Table 1] and [Table 2].
Table 1 Demographic data of the three studied groups

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Table 2 Baseline hemodynamic data and sensory level of the three groups

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Mean blood pressure showed no significant difference between the three groups after spinal anesthesia throughout the study period. It decreased insignificantly after spinal anesthesia in all the three groups [Figure 1].
Figure 1: Mean arterial blood pressure (mmHg) in the three groups. Y axis indicates MAP (mmHg). X axis indicates time (min). Data are presented as mean ± SD. C, coload; MAP, mean arterial pressure; N, no load; P, preload. No significant difference was found between the three groups

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The overall incidence of spinal anesthesia-induced hypotension was 17% (18.5% in the P group, 14.8% in the C group, and 17.8% in the N group) [Table 3]. The proportion of patients requiring ephedrine ranged from 14.8% in the C group to 17.8% and 18.5% in the N and P groups, respectively. None of these outcome measures was significantly different between the groups. Moreover, number of patients who required ephedrine and the mean amount of ephedrine required showed no significant different between the groups [Table 3]. The incidence of nausea or vomiting after spinal anesthesia in this study was less than 10%, and not significantly different between the groups [Table 3].
Table 3 Incidence and frequency of hypotension, ephedrine use, and nausea or vomiting

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  Discussion Top


Inguinal herniation is a common problem in the elderly and often requires inguinal hernia repair [13,14]. However, there are predictable physiological and metabolic changes in elderly patients that limit their ability to respond to surgical and anesthetic stress. Furthermore, high incidence of comorbidities in this population has been reported, as cardiovascular disease may contribute to perioperative adverse events and mortality [15]. Therefore, previous studies have shown that spinal anesthesia is the type of anesthesia most frequently used in the elderly patients because of its better postoperative outcome [14,16].

In this study, colloid preloading and coloading did not reduce the incidence of hypotension in elderly. Furthermore, number of patients who required ephedrine and mean amount of ephedrine required showed no significant difference between the three groups. The three groups showed insignificant difference in MAP throughout the study period. The incidence of spinal anesthesia-induced hypotension was 18.5% in the P group, 14.8% in the C group, and 17.9% in the N group. In some studies, hypotension has been reported in 25-75% of the general population after spinal anesthesia [17].

We used colloid rather than crystalloid because of the suggestion that colloid preload may augment the blood volume enough to offset the effects of increased atrial natriuretic peptide and rapid redistribution of fluid, diminishing the effects of peripheral vasodilatation and decreased venous return after the central sympathetic blockade of spinal anesthesia. The increase in intravascular volume brought about by coloading coincides with the time of maximal vasodilatation effect of spinal anesthesia, thus reducing the degree of hypotension [17]. Colloid solutions are not as rapidly redistributed to the extracellular compartment as crystalloids, thus better maintaining intravascular volume and hence cardiac output [18]. Studies conducted by Mathru et al. [19], Baraka et al. [20], and Sharma et al. [21] had supported the superiority of colloid over crystalloid. However, these studies did not compare preloading and coloading with no loading.

Few studies have investigated the impact of avoiding prehydration in elderly patients undergoing spinal anesthesia [22,23]. Coe and Revanäs [22] compared elderly groups receiving 16 and 8 ml/kg crystalloid prehydration with no prehydration before spinal anesthesia. The incidence of hypotension ranged from 24-32%, with no differences between them. Colloid (polygeline) given immediately after subarachnoid block was compared with metaraminol, an a1 agonist, given in bolus and in an infusion form. Metaraminol was more effective than colloid prehydration in maintaining systolic arterial pressure (SAP), central venous pressure, and cardiac index and in increasing the systemic vascular resistance index [23]. This is in agreement with our results: the problem is not in fluid administration (whether preloading or coloading), but it is in peripheral vascular dilatation and the decrease in peripheral vascular resistance, which occurs after spinal anesthesia [24]. This decrease in peripheral vascular resistance is better corrected by sympathomimetic (whether ephedrine or metaraminol) [23].

In addition, the findings of a study by Ogata et al. [25] are in agreement with that of our study. They found no significant reduction in postspinal hypotension after a 8 ml/kg HES preload compared with the control group, who received no prehydration. They concluded that colloid preloading did not prevent spinal anesthesia-induced hypotension.

In agreement with our study, Siddik-Sayyid et al. [26] conducted a large (n = 178), double-blind study comparing 500 ml 6% HES preloading with 500 ml 6% HES coloading. There were no significant differences between the groups in the incidence of hypotension (68 vs. 75%, respectively), severity of hypotension (defined as SBP <80 mmHg) (16 vs. 22%), or vasopressor requirements. The authors concluded that both modalities of HES loading were inefficient as single interventions. The incidence of spinal anesthesia-induced hypotension in our study was about 17%, which is less than that recorded in the study by Siddik-Sayyid et al. [26]. This might be explained by a larger sample size of their study, different types of operation, and also different age group of patients. There is a decrease in the autonomic nervous system responsiveness in elderly. Diminished sympathetic predominance and its effect on peripheral vascular resistance in this population are mainly due to atherosclerosis [27]. Thus, spinal anesthesia in elderly patients has little effect on peripheral vascular resistance and subsequent hypotension. In addition, an increased systemic vascular resistance in elderly patients, which is mainly due to atherosclerosis, could also render spinal anesthesia to have minimal effect on blood pressure in this population [15].

In their study, Carvalho et al. [28] compared the administration of 500 ml 6% hetastarch as a preload or coload and reported no differences in prophylactic requirements for vasopressors, important maternal hemodynamic, or neonatal outcome values. They concluded that hetastarch coloading was as effective as preloading for the prevention of hypotension. But they did not compare them with no load, and it is more accurate from these results to conclude that there was no difference between preload and coload on blood pressure in case of spinal anesthesia. In their study, Teoh and Sia [18] reported a significant increase in maternal cardiac output (CO) for the first 5 min after spinal anesthesia when 15 ml/kg of 6% tetrastarch was given quickly as a preload in combination with prophylactic phenylephrine boluses. However, there were no significant differences between the preload and coload groups in terms of incidence of hypotension, nausea, vomiting, and phenylephrine requirements. Therefore, the authors advocated the use of a modest preload or coload along with phenylephrine for the maintenance of SBP close to the baseline value. Again, this might reflect the importance of the use of vasopressors, and that fluid alone might have no or minimal impact on the incidence of hypotension.

Previous studies that demonstrated a beneficial effect of one fluid regimen over another [20, 29, 30] showed a 29-36% difference in the proportion of patients developing hypotension. The reported incidence of hypotension varies widely, which is partly explained by the variety of accepted definitions of hypotension. These range from a 25-30% decrease in the baseline SAP to an absolute SAP of 90 mmHg or a requirement for a bolus of vasopressor. This study is more conclusive as it had a power of 80% to detect true differences in the incidence of hypotension, with at least 27 patients in each group and a P value of less than 0.05, given that the smallest difference between the groups in the incidence of hypotension, which we took to be clinically significant, was 40%.

This study failed to demonstrate a beneficial effect from either prehydration or cohydration in elderly. Conversely, rapid infusions of large volume of fluids might be hazardous in elderly patients who mostly have cardiac dysfunction and may be at a risk for cardiac failure and pulmonary edema [15]. Moreover, colloids have a small but noteworthy incidence of anaphylactic reactions, renal impairment, and coagulopathy [31,32].

Limitations of the study

Our data might be affected by some of the features of the study design. Baseline blood pressure was taken as the mean of three readings, measured with the patient in the semirecumbent position and obtained immediately on arrival to the operating room. Subsequently, arterial blood pressure was measured in the position required for the operation, supine or lateral. Blood pressure might be affected by changes of position, in addition to the possible effects of spinal anesthesia on blood pressure. More studies are required in multicenter settings on larger number of patients with different age groups and different types of operations. This study was conducted on patients not fasting for long time with no signs of dehydration or hypovolemia. Therefore, these results could not be applied on patients who are hypovolemic or with different diseases especially cardiac and/or renal problems.


  Conclusion Top


There is no significant difference between preload, coload, or no load as regards the incidence of hypotension, proportion of patients who needed ephedrine, or the dose of ephedrine required to correct hypotension after spinal anesthesia in elderly patients undergoing inguinal hernia repair without mesh.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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