|Year : 2016 | Volume
| Issue : 2 | Page : 362-369
Repeat spinal anesthesia in cesarean section: A comparison between 10 mg and 12 mg doses of intrathecal hyperbaric (0.05%) bupivacaine repeated after failed spinal anesthesia: A prospective, parallel group study
Debasish Bhar1, Sandip RoyBasunia1, Anjan Das2, Subinay Chhaule2, Sudipta Kumar Mondal2, Subrata Bisai2, Surajit Chattopadhyay2, Subrata Kumar Mandal2
1 Department of Anaesthesiology, Midnapore Medical College and Hospital, Midnapore, West Bengal, India
2 Department of Anaesthesiology, College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
|Date of Web Publication||26-Apr-2016|
174, Gorakshabashi Road, Royal Plaza Apartment (4th Floor, Flat No 1), Nagerbazar, Kolkata - 700 028, West Bengal
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Spinal anesthesia for cesarean section is not a 100% successful technique. At times, despite straightforward insertion and drug administration, intrathecal anesthesia for cesarean section fails to obtain any sensory or motor block. Very few studies and literature are available regarding repeat administration of spinal anesthesia and its drug dosage, especially after first spinal failure in cesarean section lower segment cesarean section (LSCS) due to fear of the excessive spread of drug. The aim of our study is to compare the outcome between two different doses of 0.5% hyperbaric bupivacaine repeated intrathecally after failed spinal.
Materials and Methods: After taking informed consent and Ethical Committee approval this prospective, randomized single-blinded study was conducted in 100 parturients of American Society of Anesthesiologists I-II who were posted for elective LSCS and had Bromage score 0 and no sensory block even at L4dermatome after 10 min of first spinal anesthesia; were included in the study. Group A (n = 50) patients received 2.4 ml and Group B (n = 50) patients received 2 ml of 0.5% hyperbaric bupivacaine respectively for administering repeat spinal anesthesia. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), oxygen saturation, respiratory rate and electrocardiogram were monitored both intra- and post-operatively and complications were recorded.
Results: Incidence of high spinal, bradycardia, hypotension, respiratory complications, and nausea vomiting are significantly higher in Group A compared to Group B (P < 0.05). SBP, DBP, and HR were significantly low in Group A patients compared to Group B in the first 10 min (P < 0.05).
Conclusion: Spinal anesthesia can be safely repeated in the cesarean section with 10 mg of 0.5% hyperbaric bupivacaine provided after first spinal anesthesia, the level of sensory block is below L4and motor power in Bromage scale is 0.
Keywords: 0.5% hyperbaric bupivacaine, cesarean section, diastolic blood pressure, failed spinal, heart rate, systolic blood pressure
|How to cite this article:|
Bhar D, RoyBasunia S, Das A, Chhaule S, Mondal SK, Bisai S, Chattopadhyay S, Mandal SK. Repeat spinal anesthesia in cesarean section: A comparison between 10 mg and 12 mg doses of intrathecal hyperbaric (0.05%) bupivacaine repeated after failed spinal anesthesia: A prospective, parallel group study. Anesth Essays Res 2016;10:362-9
|How to cite this URL:|
Bhar D, RoyBasunia S, Das A, Chhaule S, Mondal SK, Bisai S, Chattopadhyay S, Mandal SK. Repeat spinal anesthesia in cesarean section: A comparison between 10 mg and 12 mg doses of intrathecal hyperbaric (0.05%) bupivacaine repeated after failed spinal anesthesia: A prospective, parallel group study. Anesth Essays Res [serial online] 2016 [cited 2019 Mar 18];10:362-9. Available from: http://www.aeronline.org/text.asp?2016/10/2/362/172725
| Introduction|| |
A significantly less but frustrating limitation of spinal anesthesia is the occasional failure (2–4%) to achieve an adequate sensory block. But still now failed spinal anesthesia and its further management is a poorly defined and relatively untouched topic in the texts and literature. The word failed implies that spinal anesthesia was attempted, but without resulting in a sensory block or a block that resulted is inadequate for that surgery. The onset of action differs between various local anesthetic agents. Bupivacaine is one of the extensively studied and well understood of these agents. Spinal anesthesia with bupivacaine is considered to have failed if anesthesia and analgesia have not been achieved within 10 min of successful intrathecal deposition of hyperbaric bupivacaine and 25 min for isobaric bupivacaine., According to current literature, failure rate of spinal anesthesia varies from 16% to <1% but most of the studies reported failure rate between 2% and 4%.
For the last two decades, cesarean section has commonly been done under spinal anesthesia. Complete failure of spinal anesthesia usually managed by either conversion to general anesthesia or by repeating the procedure of spinal anesthesia. As all pregnant patients are supposed to have a high risk of aspiration and difficulty in intubation so, conversion to general anesthesia is associated with relatively higher risk than the general population.
There are few reports and studies about repeat spinal anesthesia after the initial failure of subarachnoid block in cesarean section.,, But still now no literature clarifies about the dose of local anesthetic to be administered during the repeat spinal anesthesia for cesarean section. Some authors proposed that the dose of local anesthetic was to be reduced while administering repeat spinal anesthesia., The aim of our study is to compare the outcome, side effects, and complications of 10 mg and 12 mg doses of 0.5% hyperbaric bupivacaine repeated intrathecally after failed spinal anesthesia in cesarean section.
| Materials and Methods|| |
After taking written informed consent from patients and Ethical Committee approval this prospective, randomized single-blinded study was conducted from January 2012 to December 2014 in our Tertiary Care Institute. One hundred parturients of American Society of Anesthesiologists (ASA) I-II, aged between 18 and 40 years, were posted for elective cesarean section in which first spinal anesthesia was failed (i.e., Bromage score 0 and no sensory block even at L4 dermatome after 10 min of first spinal anesthesia) were included in our study. Patients with hypertensive disorders of pregnancy, heart disease, Bromage scale >0 and absent pinprick sensation below umbilicus after spinal anesthesia, allergy to study drug were excluded from our study. According to our institution protocol detailed preoperative checkup was done in all parturients posted for the elective cesarean section and Ringer's lactate (RL) was started at maintenance rate according to patient's body weight with the 16-gauge cannula. The monitor was attached, and preoperative vitals like heart rate (HR), noninvasive blood pressure (BP), oxygen saturation (SpO2) were measured. After all aseptic and antiseptic precautions, the subarachnoid block was performed at L3-4 or L4-5 interspace with 26-gauge Quincke needle in sitting position with 2.4 ml of 0.5% hyperbaric bupivacaine. Patients were immediately kept on supine position with a wedge under the right buttock and vitals were monitored. RL infusion rate increased immediately after the drug was deposited in subarachnoid space so that 10 ml/kg fluid was transfused over next 10 min.
Usually, effects of sensory and motor block were noted within 5 min, those who did not manifest effectiveness in 5 min were observed for another 5 min, and then they were tested for motor and sensory block. Motor block was assessed by Bromage scale: (Grade 0 - no motor block, Grade 1 - inability to raise the extended leg, able to move knees and feet, Grade 2 - inability to raise an extended leg and move knees, able to move feet, Grade 3 - complete motor block of lower limb). To assess the level of sensory block a blunt pin was taken and placed over the clavicle of the patient and the sensation of pinprick at that region was taken as reference point and then the pin was pricked at the calf muscle, knee joint and back of the thigh (L4, 3, 2), just above the groin (L1), incision line, at the level of umbilicus (T10) on both sides and compared with reference point. Sensation to cold was also tested in similar fashion on both sides with an ice cube. Surgery was allowed to start on patients who had Grade 3 in Bromage scale and no pinprick or cold sensation at the level of the umbilicus.
Those ASA I-II patients who had Bromage score 0, pinprick and a cold sensation similar to the reference point at the back of the thigh, knee, and calf muscle (L2, 3, 4 dermatome) were considered for inclusion in the present study. After obtaining informed patient consent, the patient was allocated to either Group A or Group B according to a computer generated random number selected by the patient.
Group A patients received 2.4 ml, and Group B patients received 2 ml of 0.5% hyperbaric bupivacaine respectively. With same precautions subarachnoid block was again performed with 26-gauge Quincke needle in sitting position one space above or below compared to first attempt (one space above in patients where previous spinal was attempted at L4-5 interspace or one space below in those patients who had previous spinal at L3-4 interspace) by a senior anesthesiologist who was working more than 3 years in anesthesiology. Patients were made supine immediately with left lateral uterine displacement by wedge under the right buttock, and monitoring started. After confirming the onset of spinal anesthesia by no pinprick and cold temperature sensation at T10 dermatome on both sides and Bromage score of 3 in lower limbs, the operation was allowed to start. If the patient complained of a pinprick and cold temperature sensation 10 min after repeat spinal was given at T10 dermatome, then general anesthesia was administered and excluded from our study. However, fortunately, a repeat dose of spinal anesthesia was proved to be successful in all the cases, and no patient had been excluded from our study.
After the onset of the effect of spinal anesthesia confirmed by sensory and motor block, RL was transfused at 20 ml/kg for first 20 min then at 10 ml/kg/h for rest of the intraoperative period. Moist O2 was administered at4 L/min via polymask was administered throughout the intraoperative period.
Both systolic BP (SBP) and diastolic BP (DBP) were monitored at 2 min interval for initial 20 min then at 3 min interval for rest of the operation. If SBP falls more than 20% of the preoperative value or <100 mmHg then injection phenylephrine 100 mcg intravenous bolus was administered. Continuous HR monitoring was done and injection atropine 0.6 mg was administered if HR <50/min and repeated if HR remained <50/min even after 1 min. SpO2, respiratory rate (RR) and electrocardiogram (ECG) was monitored throughout the procedure. The level of sensory block was assessed by pinprick. The incidence of complications such as hypotension, bradycardia (HR <60/min), respiratory complications (either RR <10/min or SpO2 <94%), nausea vomiting, shivering, urinary retention, postdural puncture headache, and any neurological symptoms (intra- and post-operative) were all noted. All patients were monitored for 2 h postoperatively with continuous HR, ECG, and SpO2 monitoring and BP was checked at 10 min interval.
Values were expressed as mean ± standard deviation (SD) and percentage (%) for continuous and discreet variables, respectively. Results were analyzed by unpaired Student's t-test for parametric data and Mann–Whitney U-test for nonparametric data. Fisher's exact test and Chi-square test were used for categorical data as appropriate. P < 0.05 was considered statistically significant. All statistical tests were done by “Statistica” version 9 (StatSoft Incorporation, Tulsa, Oklahoma, USA; 2009).
The sample size was estimated using the requirement of phenylephrine for combating the hypotension (after administration of spinal anesthesia) among two groups as the main primary variable. The average requirement in each group was 150 µg and to detect a difference of 10% (i.e., 15 µg), at the P < 0.05 level, (with a probability of detecting a difference of 80%) (1 − beta = 0.80). On the basis of previous study assuming that within-group SD was 60 µg and we needed to study at least 44 parturient per group to be able to reject the null hypothesis which will be increased to 50 mothers per group for possible dropouts. Raw data were entered into an MS Excel spreadsheet and analyzed using standard statistical software SPSS ® statistical package version 18.0 (SPSS Inc., Chicago, IL, USA). Categorical variables were analyzed using the Pearson's Chi-square test. Normally distributed continuous variables were analyzed using the independent sample t-test and P < 0.05 was considered to be statistically significant.
| Results and Analysis|| |
We recruited 50 subjects per group, more than the calculated sample size. There were no dropouts that mean all the repeat spinal anesthesia cases were successful. Fifty patients in the higher (2.4 ml) dose repeat spinal bupivacaine Group A and 50 patients in the lower (2 ml) dose repeat spinal bupivacaine Group B were eligible for effectiveness analysis.
The age, body weight, height, and duration of operation were found to be comparable [Table 1]a. The difference between the two groups regarding the interspace at which repeat spinal anesthesia was administered is also not significant statistically (P > 0.05). Six percentage patients of Group A had high spinal which is significantly higher than Group B (P < 0.05) [Table 1]b. [Table 2] shows that there is no significant difference in SBP between the two groups except at 6, 8, and 10 min when SBP in Group A is significantly lower than Group B (P < 0.05). From [Table 3], it is evident that DBP in Group A is significantly less than Group B between 4 and 10 min (P < 0.05). From [Table 4] is observed that HR is significantly less in Group A at 4 and 6 min compared to Group B (P < 0.05).
We have taken SBP, DBP, and HR values for statistical analysis up to 55 min because it covers 2 SD of the duration of the operation.
From [Table 5] it is found the requirement of vasopressor and atropine is significantly high in Group A compared to Group B [Table 4].
From [Table 6] it is evident that incidence of hypotension, bradycardia, respiratory complications, and nausea vomiting is significantly higher in Group A compared to Group B (P< 0.05). No patients of our study required general anesthesia but in 4 (8%) patients of Group B supplemental fentanyl, N2O and O2 was administered intraoperatively as patient complained of vague visceral discomfort after the operation was started. Postoperatively none of the patients had any incidence of hypotension, bradycardia or respiratory complications. ECG was uneventful in all the patients in the intra- and post-operative period. None of the patients received repeat spinal anesthesia reported any weakness, paresthesia, loss of sensation or any other type neurological symptoms in lower limbs up to 6th postoperative day. [Flow chart 1]: Consort flow diagram shows the patient enrollment, allocation, follow up, analysis of all the patients in the study.
| Discussion|| |
Spinal anesthesia is the widely used anesthetic technique for cesarean section but having an occasional failure rate between 2% and 4% in current literature.
Common technical errors which attribute to failed spinal anesthesia despite successful cerebrospinal fluid (CSF) tap are the improper rate of injection, entering intrathecal space at a lower spinal level than required surgical level, needlepoint partly outside of dural sac and needle in the ventral epidural region are.
Inadequate dose of local anesthetic or loss of the drug from the junction of the needle and syringe may be other causes of failed block. Loss of potency of the drug due to prolonged exposure to light or high CSF alkalinity may result in failure of spinal anesthesia or in the case of ester type of local anesthetic the drug may be hydrolyzed by blood pseudo-cholinesterase when there is bloody tap.,
Anatomical variations such as kyphosis, scoliosis, and spinal stenosis due to previous intrathecal chemotherapy or surgery may interfere with the spread of local anesthetic in the intrathecal space.,
Rarely the ligaments that form complete septae and results in unilateral or of insufficient cephalad spread. And due to physiological “resistance” to the actions of local anesthetics probably due to modulation of sodium channels.
In the current literature, only two attempts are recommended since multiple punctures can cause nerve injury and predispose to hematoma formation. Lee et al. had reported a case of cauda equina syndrome following repeated failed spinal. A large concentration of local anesthetic in a small area may lead to neurotoxicity due to some anatomical abnormality preventing the even spread of local anesthetic. To reduce this possibility, we have changed the vertebral interspace while repeating the spinal anesthesia.
There is a possibility of differential block resulting in autonomic blockade but no sensory or motor impairment due to low concentration of the local anesthetic, thus resulting in excessive high spread of local anesthetic when spinal anesthesia is repeated. To exclude this possibility we have checked that bupivacaine used in the failed spinal belongs to the same batch from which all the spinal anesthesia has been administered on that day, and it was stored in the refrigerator in a cardboard container.
Sympathetic out flow occurs from T2 to L2 segments of spinal cord so; the level of sensory block has been tested up to L4 in the present study because if there is differential block no sensory impairment at L4, it usually signifies no sympathetic block at L2 level.
In our study, only ASA I, and II patients have been selected and used bupivacaine as a local anesthetic, thus chance of CSF alkalinity is, and hydrolysis by pseudocholinesterase is minimal.
About 12 mg of hyperbaric bupivacaine has been used in our study for an initial spinal block because both Riley  and Ginosar et al. suggested a dose of 12 mg bupivacaine for cesarean section. As authors suggested a lower dose of local anesthetic while repeating the subarachnoid block due to fear of excessive cephalad spread of block we have compared between 12 and 10 mg of 0.5% hyperbaric bupivacaine in the present study.,
In literature incidence of hypotension in the cesarean section has been described to over 80% depending on the dose which is similar to a present study (82% in Group A and 46% in Group B). However, the incidence of bradycardia occurred in Group A (12%) is much higher than reported incidence of bradycardia (2.5%) during cesarean section under spinal anesthesia.
In a previous study by Pokharel, reported a higher incidence of bradycardia (5.5%), high spinal block (5.5%), and low spinal block (5.5%) compared to Group B of the present study when they repeated spinal anesthesia with 1.8 ml of 0.5% hyperbaric bupivacaine in cesarean section. This difference may be due to the difference of case selection in the two studies. In a previous study, they had repeated spinal when the patient complained of pain sensation at the incision line and did not exclude those cases which had sensory block below the line of incision and had some degree of motor block. In another study Abraham and Philip has concluded that giving a second spinal is a safe and reliable method of management of failed spinals. But, they also had repeated the drug in patients with partial motor and sensory block.
In our study SBP, DBP, and HR were significantly low in Group A patients compared to Group B in the first 10 min. The incidence of high spinal, respiratory complications, bradycardia, hypotension, and nausea vomiting are significantly higher in Group A compared to Group B. Respiratory complications which occurred in three patients due to high spinal in Group A was managed by assisted ventilation with 100% O2 for 5–10 min, correction of hypotension and assurance. None of the three patients had any loss of consciousness. All the cases of bradycardia which occurred during our study were managed successfully with atropine.
Recent literature also support the administration of repeat spinal anesthesia if there is no emergency as it avoids the risk of aspiration and difficult airway and preserves patient preference for spinal anesthesia.
Limitations of our study were, we had not measured sedation score, visual analogic scale score, and plasma catecholamine or stress hormone concentrations which may reveal relations between sympatholytic properties of local anesthetic agents after spinal anesthesia and incidence of hypotension, bradycardia produced by it. Another limitation is that we compared the only two doses of bupivacaine, based on the known optimal doses. However, a study with large sample size needs to be conducted to ascertain optimal dose of hyperbaric bupivacaine which can be used safely and successfully in repeat spinal anesthesia in parturient women.
| Conclusion|| |
We can recommend that a dose of 10 mg of 0.5% hyperbaric bupivacaine can be safely be repeated after failed spinal in the cesarean section without significant hemodynamic alteration.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]