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© Borgis - Anaesthesiology Intensive Therapy 1/2001
Wojciech Pietrzyk, Laura Wołowicka
Combined spinal-epidural analgesia for elective caesarean section - intraoperative period
Department of Anaesthesiology, Regional Specialised Hospital of Obstetrics, Gynaecology and Neonatal Care.
Head: P.Szpak, M.D., Kielce, Poland. Dept of Intensive Medical Care and Pain Therapy.
Head: prof. L.Wołowicka, Poznań, Poland
Summary
We conducted a prospective randomized study to assess effectiveness of the combined spinal - epidural analgesia (CSEA) in eighty parturiens, scheduled for elective caesarean section, randomly divided to receive either the combined block or epidural analgesia. In the CSEA group onest of the block was faster, surgical analgesia and relaxation were better and the patient satisfaction score - higher. We therefore recommend this method for the elective caesarean section surgery.
One of the methods, rapidly gaining popularity during recent years, is the combined spinal-epidural anaesthesia (CSEA). Many authors stress that CSEA, combining the efficacy and depth of subarachnoid block with the versatility of continuous epidural analgesia, is superior to each of the two methods alone [1, 2, 3, 4].
The study presents the results of multifactoral, prospective analysis of CSEA effectiveness in elective caesarean section. The most important parameters assessed included the rapidity of onset of action, the extent of senso-motoric block in parturients, as well as frequency of untoward effects.
METHODS
Eighty parturients scheduled for elective caesarean section were included in the study. The patients were in good general condition - grade I or II, according to the ASA scale. In all cases the pregnancy was single, at term, without a history of complications. The protocol of the study was approved by the local Ethical Committee for Clinical Studies in Humans and informed consent was obtained from each patient.
Premedication consisted of ranitidine 50 mg, metoclopramide 10 mg i.v. and 30 ml 0.3 M solution of sodium citrate given orally. 150 mL of Ringer's solution was also administered by a rapid i.v. infusion. The parturients were randomly divided into two groups of 40 patients each (group I: CSEA, group II: continuous epidural anaesthesia- CEA).
In group I the CSEA was performed using the "needle via needle" technique. The procedure was carried on the patient in the lateral decubitus position. After localising L3-L4 intervertebral space a 16G Tuohy needle (Epidural Minipack, Portex, Great Britain) was introduced by median approach and the epidural space identified by the "loss of resistance" technique. Then, a subarachnoid Qincke needle (120 mm length, Spinocan 26G, B.Braun Melsungen, Germany) was introduced into the lumen of the Tuohy needle. After identification of subarachnoid space 0.5% isobaric bupivacaine solution (Marcaine Spinal 0.5%, Astra, Sweden) and 25 ?g of fentanyl was injected. The dose of bupivacaine depended on the height of the patient: those measuring 165 cm or more received 12.5 mg of bupivacaine, the others - 10 mg. After withdrawal of the subarachnoid needle, an epidural catheter was introduced and (after an aspiration test) primed with physiologic saline solution. The patient was placed in a supine position on the operating table inclined at least 15° to the left. If the desired level of blockade was not reached after 15 minutes from subarachnoid injection, 0.5% bupivacaine was administered through the epidural catheter. 1 mL of analgesic was given for each non - anaesthetised segment below Th4, until satisfactory level was reached.
Patients from group II received continuous epidural anaesthesia. The position of the patient and technique for identification of the epidural space were identical, as in group I. After a negative result of the aspiration test, 3 mL of 0.25% bupivacaine with adrenaline (Marcaine 0.25% Adrenaline, Astra, Sweden) was injected. Then, 0.5% bupivacaine solution was administered in fractionated doses, until a sensory block up to the Th4 level developed. After clamping of the umbilical cord 75 ?g of fentanyl (in 10 mL of saline) was administered additionally. In 2 patients; in spite of the correct level of sensory block some areas of the abdomen and groins skin remained non - anaesthetised. These patients were excluded from the study. In all cases time intervals (table I) were measured. The degree of motor block was assessed according to the Bromage scale [5], just before surgical draping of the patient, and the level of sensory block - by a pin-prick test.
Table I. Time intervals
SymbolDescriptionUnit
ATh4TTime from injection of analgesic dose of bupivacaine to Th4 sensory blockademin
IDT (IDT1+IDT2)Time from injection of analgesic dose of bupivacaine to umbilical cord clampingmin
IDT1Time from injection of analgesic dose of bupivacaine to skin incisionmin
IDT2Time from skin incision to umbilical cord clampingmin
UDTTime from uterine muscle incision to umbilical cord clampings
Blood pressure values, were recorded by a non-invasive method (Diascope 2 Vismo, Simonsen & Weel, Denmark) every minute till the delivery of the foetus and every 5 minutes thereafter. Hypotension was defined as a 30% decrease of mean pressure value of as compared with the baseline, or systolic blood pressure below 100 mmHg (13.3 kPa). The number of hypotensive episodes and their duration were also recorded during the IDT time interval.
The effectiveness of sensory block was assessed by the patients themselves by quantifying the intensity of nociceptive stimulation from the operative field. During closure of the peritoneal cavity they were asked to express their pain perception in 10-point numeric scale (NRS), where 0 means no pain and 10 points - unbearable pain. After the operation the patients were asked to give their opinion on the course of anaesthesia in a 4-point verbal scale (VRS): very good, good, fair, poor [6]. Untoward effects of technique employed, such as nausea and vomiting, skin itching or shivering, were also assessed.
Statistical analysis of the results was performed with the Student's T-test, Chi² test and nonparametric Mann-Whitney rank U - test. Correlation assessment was based on Chi², linear correlation on Pearson's test and rank correlation on Spearman's R- test. The level of statistical significance was taken as p<0.05.
RESULTS
No statistically significant differences were found between groups in anthropometric parameters, or in clinical indications to caesarean section (table II).
Table II. Characteristics of patients
ParameterCSEA (n=40)EA (n=40)Statistical significance
age (years)26.7±5.727.7±6.5NS
body weight (kg)75.0±10.375.5±10.1NS
height (cm)75.0±10.3164.0±5.3NS
primiparity17 (42.7%)22 (55%)NS
Indications for a caesarean section:

   
foetal malposition16 (40%)15 (37.5%)NS
previous caesarean section13 (32.5%)14 (32.5%)NS
obstetric history7 (17.5%)8 (20%)NS
ophtalmologic and orthopaedic indications4 (10%)3 (7.5%)NS
Mean values of time intervals: ATh4 T, IDT1 and IDT were statistically significantly lower in group I (CSEA), than in group II (CEA) patients (table III).
The mean ATh4 T interval in CSEA group was less then half shorter then in CEA group. In 5 patients from group I (CSEA) supplementation of analgesia via epidural catheter was required. This was the cause of lengthening ATh4 T in these patients, and in consequence - big individual differences and increasing the value of standard deviation in this group. Intervals IDT2 and UDT, dependent mainly from surgical technique, did not differ significantly between groups (table III).
Table III. Mean values of time intervals
TimeCSEACEAStatistical significance
ATh4Tmin.10.7±6.426.7±5.1p<0.001
IDTmin.31.4±9.841.7±11.5p<0.001
IDT1min.19.4±8.230.7±9.5p<0.001
IDT2min.12.1±6.211.1±6.7NS
UDTs.69.6±270.4±29NS
Motor blockade, as assessed with the Bromage scale, was significantly more pronounced in patients from CSEA, than CEA group (table IV).
Table IV. Motor block (according to the Bromage scale) immediately before skin incision
Degree of motor blockadeCEA
n (%)
CSEA
n (%)
Statistical significance
00p<0.001
09 (23.7%)
II°13 (32.5%)19 (50%)
III°27 (67.5%)10 (26.3%)
No patient expressed pain perception from the operative field above 2 points in the NRS scale. There exists, however, statistically significant difference between CSEA and CEA parturients: in these latter, the mean NRS score was higher (table V).
Table V. Intensity of nociceptive stimuli reception from the operative field (NRS scale)
NRS score (points)CEA
n (%)
CSEA
n (%)
Statistical significance
031 (77.5%)21 (55.3%)p<0.05
1.5 (12.5%)10 (26.3%)
24 (10%)7 (18.4%)
300
No differences between groups were observed in rate of nausea, vomiting, shivering, skin itching, hypotension nor its mean duration time (table VI).
Table VI. Untoward effects during the intraoperative period
Symptomn (%)n (%)Statisticalsignificance
nauseaand vomiting9 (22.5%)11 (28.5%)NS
shivering12 (30%)10 (26.3%)NS
itching1 (2.5%)2 (5.3%)NS
hypotension26 (65%)18 (47%)NS
mean duration115±6497±58NS
The subjective opinion of the patients on the quality of anaesthesia differed significantly between groups (p<0.05). More patients from CSEA group assessed anaesthesia as very good. There were more good and fair notes in the CEA group. Anaesthesia was qualified as very good or good by 95% of parturients from CSEA, and by 81.6% - from CEA group. No negative notes were given (table VII).
Table VII. Assessment of the quality of anaesthesia by the patients
NoteCSEA
n (%)
CEA
n (%)
Statistical significance
very good25 (62.5%)14 (36.8%)p <0.05
good13 (32.5%)17 (44.8%)
fair2 (5%)7 (18.4%)
poor00
There was a negative correlation between the intensity of sensory stimulation from the operative field and the assessment of the quality of anaesthesia in both groups of patients (CSEA: R=-0.3205; EA: R=-0.5380). A significant difference (p<0.05) was also observed between the variables: nausea/vomiting and assessment of anaesthesia quality. This suggests that the effectiveness of sensory block and adverse effects, unpleasant for the patient, significantly influence the subjective assessment of the quality of anaesthesia. Other adverse effects did not significantly influence the overall impression of the patients on anaesthesia.
DISCUSSION
The dose of subarachnoidally administered isobaric bupivacaine was titrated to cause a rapid onset of anaesthesia, enabling the beginning of surgery. The role of epidural component in CSEA group was a priori limited to secure the patients in whom spinal analgesia was inadequate and to secure analgesia in the postoperative period. Other authors [7,8] present the same approach, favouring the rapid onset of anaesthesia at the cost of more pronounced haemodynamic consequences of high sympathetic block. Thanks to this approach, the mean ATh4 T interval (depending mainly on the method of anaesthesia) was almost half as long in CSEA, comparing with the CEA group. This enabled the shortest possible time from analgesic injection to the start of the caesarean section, which is very often of main importance in obstetric anaesthesia. The use of a "single shot" technique and premixed solutions of local analgesic drugs may markedly shorten the time needed to obtain a satisfactory level of epidural anaesthesia. Fernando and Jones [9], using an alkalised solution of bupivacaine and lidocaine with adrenaline reported the reduction of time to reach Th4 level of block to 12.7 minutes. This is comparable with our results (mean value of ATh4 T interval) in the CSEA group. The "single shot" technique is, however, not free from life-threatening complications, which may arise after inadvertent administration of a large dose of analgesic solution to the subarachnoid or intravascular space.
No equality sign can be posed between the techniques compared, in terms of reaching the adequate level of surgical anaesthesia. In our study, the need to use an alternative method arose only in 2 patients (5%) from the CEA group. According to Lyons [10], both subarachnoid as well as epidural anaesthesia is ineffective in about 4% of patients, and need to be replaced by other anaesthetic techniques. If both these methods are used simultaneously, the probability of insufficient anaesthesia drops to 0.16%. The author cited above stressed, that the need for conversion of CSEA to general anaesthesia is observed in 1:900 patients scheduled for caesarean section. Westbrook, who demonstrated that the rate of failed CSEA for caesarean section (performed by the experienced and in-training anaesthesiologists) did not exceed 0.67% [11], published similar observations.
In the present study the patients in whom CSEA was performed (as compared with CEA) expressed a more favourable opinion on the reduction of sensory stimulation from the operative field (NRS scale). This observation is consistent with the results published by other authors [12, 13].
The degree of muscular motor block, assessed according to the Bromage scale, was higher in the CSEA group. This is in agreement with the clinical experience of other authors [1,14], reported in their studies on optimal dosing of drugs in CSEA. They stated that the best degree of muscle relaxation (as assessed by the surgeon) was observed in patients in whom the component of subarachnoid analgesia overweighed the epidural one. Taking into account the role of adequate muscle relaxation in rapid delivery of the foetus during caesarean section, deeper motor blockade during CSEA seems to play a substantial role.
The rate of nausea or vomiting during the procedure was similar to that reported in the literature [15]. These adverse effects of spinal anaesthesia, unpleasant for the patients, may be attributed to hypotension, admixture of opioids, direct stimulation of peritoneum, emotional factors and slower passage of the upper gastrointestinal tract (characteristic for the advanced pregnancy). Shivering was observed/reported by the patients as frequently, as in other authors reports [14,15]. It seems that this mechanism of defence against excessive heat loss could be triggered by rapid infusion of non-heated i.v. fluids (temperature 20-22°C). Equally, if not more, important may be the results of autonomic block: thermoregulation disturbances (caused by increased skin blood flow) diminished feedback information from skin thermoreceptors and altered pattern of heat redistribution [16]. The frequency of generalised skin itching was low, as compared with other authors' results [7] and did not differ significantly between our groups.
In both groups of patients, arterial hypotension was observed frequently, but similar to other authors' observations [17]. The cause might be the elective mode of caesarean section and non - administration (as a rule) of ephedrine preoperatively. Hypotension occurred more frequently (although without statistical significance) in the CSEA group, which may be attributed to a faster spread of sympathetic block [14]. Episodes of hypotension, however, were easy to correct, as is reflected by their short duration.
Subjective assessment of the quality of anaesthesia by the patients revealed the superiority of CSEA over CEA, comparable with other authors' observations [18]. Statistical analysis of our results confirms the role of negative influence of pain perception and nausea/vomiting on the overall assessment of anaesthesia. Totally conscious patient was able, during surgery, to express her own opinion, based on premises frequently ignored by the medical personnel. This factor, influencing the choice of the method of a safe and effective method of anaesthesia, introduces to the anaesthetic practice the definition of "quality of anaesthesia". On the basis of our results, presented above, we can make a conclusion that CSEA for elective caesarean section can be an advisable method of regional anaesthesia.
CONCLUSIONS
1. Combined subarachnoid-epidural anaesthesia allows a faster beginning of caesarean section than epidural anaesthesia alone.
2. The degree of sensory and motor block is more pronounced after the combined subarachnoid - epidural, than after epidural anaesthesia alone.

Originally published in Anestezjologia Intensywna Terapia 31; (2), 83-87, 1999.
Piśmiennictwo
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Adres do korespondencji:
Mazurska Str. 34; 25-342 KIELCE, Poland

Anaesthesiology Intensive Therapy 1/2001