|Year : 2018 | Volume
| Issue : 3 | Page : 231-239
Optimizing heavy marcaine dose for spinal anesthesia in short stature pregnant female individuals undergoing cesarean section
Wael Elgharabawy, Ramy Mahrose
Department of Anesthesiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
|Date of Submission||15-Dec-2017|
|Date of Acceptance||17-Feb-2018|
|Date of Web Publication||31-Aug-2018|
Department of Anesthesiology, Faculty of Medicine, Ain Shams University, Cairo
Source of Support: None, Conflict of Interest: None
Background and objectives Hypotension after spinal anesthesia is still widespread in cesarean delivery, especially in pregnant women with short stature. The use of a reduced dose of local anesthesia allows adequate spinal anesthesia with minimal hypotension. We investigate the lowest dose of heavy bupivacaine that can be used to reduce the frequency of hypotension associated with adequate spinal anesthesia in short stature pregnant female individuals undergoing cesarean section.
Patients and methods Sixty women scheduled for cesarean section were divided into three groups of patients (20 in each group) receiving spinal injections of 0.04 mg heavy bupivacaine/cm height (group A), 0.05 mg heavy bupivacaine/cm height (group B), and 0.06 mg heavy bupivacaine/cm height (group C). A decrease in systolic pressure greater than 20% of the baseline was considered low blood pressure and was treated with a bolus of 5–10 mg intravenous ephedrine. The quality of surgical anesthesia was assessed among groups.
Results Groups B and C were assigned a higher sensory level block than group A after spinal anesthesia, and the difference was statistically significant (P<0.05). In group C, 18 (90%) patients developed a complete motor block, while in group B, 16 (80%) patients developed a complete motor block, compared with patients of group A in which only four (20%) patients developed complete motor block, and the difference between groups was statistically significant (P<0.05). The spinal block resulted in excellent surgical anesthesia in groups B and C compared with group A. Patients in group C were more likely to develop hypotension than patients in groups B and A. There was no significant statistical difference between the groups as regards neonatal outcome.
Conclusions This study showed that the use of spinal anesthesia in pregnant women of short stature using heavy bupivacaine at a concentration of 0.05 mg/cm body weight showed a clear benefit in terms of adequate anesthesia and stable hemodynamics.
Keywords: cesarian section, heavy marcaine dose, short stature, spinal anesthesia
|How to cite this article:|
Elgharabawy W, Mahrose R. Optimizing heavy marcaine dose for spinal anesthesia in short stature pregnant female individuals undergoing cesarean section. Res Opin Anesth Intensive Care 2018;5:231-9
|How to cite this URL:|
Elgharabawy W, Mahrose R. Optimizing heavy marcaine dose for spinal anesthesia in short stature pregnant female individuals undergoing cesarean section. Res Opin Anesth Intensive Care [serial online] 2018 [cited 2019 Apr 25];5:231-9. Available from: http://www.roaic.eg.net/text.asp?2018/5/3/231/233602
| Introduction|| |
Cesarean section under spinal anesthesia has become increasingly common, especially in the last decade, wherein it has become the preferred method for most anesthesiologists. This is mainly attributable to increased maternal mortality with general anesthesia (GA) and benefits for the mother. However, spinal anesthesia is associated with serious complications in the pregnant patient, with maternal hypotension occurring frequently. It is believed to affect up to 95% of patients, and can reduce placental perfusion of the uterus, leading to fetal acid–base abnormalities .
Physiological changes with pregnancy are a challenge for the anesthesiologist during spinal and GA. Volatile anesthetic requirements are reduced by 28–30%. Epidural vein engorgement decreases the space of the available cerebrospinal fluid, extending the spread of injectates into the subarachnoid space .
The expected blood loss is about 300–500 ml for vaginal delivery and about 800–1000 ml for cesarean delivery. Packed cell volume increases by 20% during pregnancy (although ‘anemia’ of pregnancy). Moreover, stroke volume, heart rate, and cardiac output increase by 50% during pregnancy .
Liver enzymes are slightly increased, which is normal. Serum proteins are decreased, increasing the effectiveness of different drugs. Plasma cholinesterase activity declines ∼25% after 10 weeks, which may prolong the duration of the action of succinylcholine. Furthermore, coagulation factors increase during pregnancy .
Aortocaval syndrome occurs in 20% of pregnant women and can lead to fetal acidosis and intravascular injections. This is to be treated by placing patients in the left lateral position or using the right hip wedge. Mucous swelling of the capillaries may affect the airway. Pregnant patients have an increased risk of aspiration. The renal blood flow increases by ∼50% (identical to changes in cardiac output) .
In the medical context, short stature is commonly defined as adult height that is more than two SDs below average age and sex . This typically includes adult men shorter than 166 cm and adult women shorter than 153 cm .
Short stature female patients present a challenge for the anesthesiologist during spinal anesthesia, because they need to reduce the dose of heavy bupivacaine, to avoid high spinal anesthesia and unstable hemodynamics .
When we looked at the literature on reference doses of anesthesia given to patients with short stature, we found that the dose we used was identical to that of Samra, who used a minimum effective dose (effective spinal block in 95% of cases of women undergoing cesarean section) of intrathecal bupivacaine (0.06 mg/cm body height), in puerpera with short stature, and reached a satisfactory block height .
The aim of our study was to identify the optimum dose (least effective dose with least hemodynamic affection) of heavy bupivacaine for spinal anesthesia for short stature pregnant female individuals undergoing cesarean section.
| Patients and methods|| |
The study was conducted at the obstetric operating room of Ain Shams University hospitals during a period of 6 months. The study protocol was approved by the ‘research and ethics committee’ of Anesthesia and Intensive Care Department, Ain Shams University. Informed consent was obtained from all patients or their legal guardians before enrolling in the study.
Sixty pregnant female individuals were enrolled in the study, with a range of age between 19 and 40 years and height below 153 cm. All patients were of American Society of Anesthesiology physical status 1 or 2 and were planned for elective cesarean section.
After completion of the baseline laboratory work, the patients were randomly allocated into one of three groups (20 patients each), using the closed sealed envelope method of randomization.
Group A consisted of 20 patients who received lumbar spinal anesthesia at a dose of 0.04 mg/cm height.
Group B consisted of 20 patients who received lumbar spinal anesthesia at a dose of 0.05 mg/cm height.
Group C consisted of 20 patients who received lumbar spinal anesthesia at a dose of 0.06 mg/cm height.
Exclusion criteria for the study included the following: patient refusal to consent (absolute), infection in the patient’s back near the proposed site of the injection, coagulation disorder (defined as prothrombin time: >18 s, partial thromboplastin time: >40 s, international normalized ratio: >1.5, clotting time: >8 min, platelet disorder: platelet count: <100.000, bleeding time: >4 min), HELLP syndrome (defined as Hemolysis, Elevated Liver enzymes, Low Platelet count), receiving any anticoagulant drugs, pre-existing neurological disease or psychic patients, history of cardiac and respiratory system failure, known allergy to local anesthetic drugs, coexisting renal disease, and eclamptic patients.
On arrival to the operating room, all patients were continuously monitored with ECG, noninvasive blood pressure, and pulse oximetry; urinary catheter was inserted if not already present. A 16-G cannula was inserted in a peripheral vein, and 500 ml Ringer’s solution was given as loading over 15–20 min.
Patients were put in the sitting position, and, under complete aseptic precautions with full sterilization of the skin covering the lumbar spine and covering the patients back with sterile towels, local anesthesia was administered by infiltration of the skin and subcutaneous tissues with 3–5 ml lidocaine 1%. A 25-G standard quincke-babcock needle was inserted at the L3−4 interspace. The subarachnoid space was identified by cerebrospinal fluid; thereafter, heavy bupivacaine was injected into the subarachnoid space in the following doses: 0.04 mg/cm height for group A, 0.05 mg/cm height for group B, and 0.06 mg/cm height for group C. A bellow is placed under the right side of the patient to avoid aortocaval compression after lying flat. Thereafter, breathing oxygen by oxygen mask was used.
The upper level of the blockade was tested by the pin-prick test (as indictor for sensory level of block, T4 block is required for adequate block during caesarian section), Bromage scale (BS) (BS 0, full flexion of knees and feet; 1, just able to move knees; 2, able to move feet only; 3, unable to move feet and knees, and complete motor block was defined as BS 3) was used as indicator for motor block. Noninvasive blood pressure measurement was recorded at every 3 min interval during the first 15 min after the spinal injection and every 5 min thereafter, If it decreased by more than 20% below baseline level, the patient was given intermittent doses of ephedrine 5–10 mg intravenously, until systolic blood pressure (SBP) was regained to 20% of the baseline value. If inadequate spinal anesthesia occurred, GA was used for the patients, and they were excluded from the study.
The newborns’ Apgar scores and umbilical pH values were recorded immediately after delivery.
Analysis of data was carried out by an IBM computer using Statistical Program for Social Science, version 16 (SPSS Inc., Chicago, Illinois, USA) as follows:
- Description of quantitative variables as mean±SD.
- Description of qualitative variables as number and percentage.
Statistical analysis was performed using statistical tests including the Student’s t-test, analysis of variance test, Tukey’s test, χ2-test, and table analysis. P values less than 0.05 were considered significant.
| Results|| |
As regards age, gestational age, body weight, operation length, and height of patients, there were no statistically significant differences between groups (P>0.05) ([Table 1] and [Figure 1]).
As regards the peak sensory level after spinal anesthesia
Peak median cephalad sensory block to touch sensation was significantly higher (by at least two dermatomes) in groups B and C, with the highest level of anesthesia occurring at the second thoracic dermatome in group C and at the third thoracic dermatome in group B, than in group A, with the highest level of anesthesia occurring at the fifth thoracic dermatome, and the difference was statistically significant (P<0.05). There was no significant statistical difference between groups B and C as regards peak sensory level (P>0.05) ([Table 2] and [Figure 2]).
As regards motor block after spinal anesthesia
In group C, 18 (90%) patients developed complete motor block (BS=3), whereas in group B, 16 (80%) patients developed complete motor block, compared with patients of group A in which only four (20%) patients developed complete motor block, and the difference between groups was statistically significant (P<0.05). Two patients in group C and three patients in group B developed partial motor block (BS=1 and 2) after spinal anesthesia, whereas 11 patients in group A developed partial motor block. Five (25%) patients in group A developed nonmotor block, whereas only one (5%) patient in group B and no (0%) patient in group C developed nonmotor block after spinal anesthesia, and the difference between groups was statistically significant (P<0.05) ([Table 3] and [Figure 3]).
As regards adequacy of block after spinal anesthesia
Spinal block was sufficiently intense in groups B and C to provide surgical anesthesia for patients, although two (10%) patients from group C and four (20%) patients from group B required conversion to GA, because of inadequate surgical anesthesia.
Sixteen (80%) patients of group A showed nonadequate block needed for caesarian section after spinal anesthesia, although four (20%) patients developed adequate block.
For group A, GA was used to complete the surgery for patients who developed nonadequate block for caesarian section ([Table 4] and [Figure 4]).
As regards occurrence of hypotension after spinal anesthesia
- The baseline SBP readings showed no statistically significant difference between groups (P>0.05).
- Group C showed a decrease in SBP values (at 6 and 9 min), after spinal anesthesia, in comparison with baseline readings, and in comparison with groups A and B, which was statistically significant (P<0.05); however, there were no statistically significant changes in SBP in groups A and B after spinal anesthesia.
- For group C, rescue doses of ephedrine, as a treatment for decreased SBP of more than 20% of the baseline value, were used ([Table 5] and [Figure 5]).
Neonatal outcome parameters
Apgar scores after 1 min of delivery and umbilical pH values were similarly excellent in the groups, and there were no significant differences between the groups (P>0.05) ([Table 6] and [Figure 6]).
| Discussion|| |
In the present study, we tried to optimize the dose of heavy marcaine during spinal anesthesia for short stature pregnant female individuals undergoing cesarean section; the advantage of using the optimum dose is that adequate spinal anesthesia with least haemodynamic affection to improve the outcome is achieved.
Group A showed no statistical significance in the nonadequacy of spinal block for cesarian section compared with groups B and C, meaning that the dose used was not adequate for surgery. This corresponds to observations that have long been reported by many authors (such as Paulzilberman ). Group C showed statistically significant increase in hemodynamic instability in patients compared with groups B and A.
Raffaele , showed that a low dose of up to 0.06 mg/cm height represents the dose of intrathecal bupivacaine, which represents an effective spinal block in 95% of short stature women who undergo elective cesarean section.
Heavy bupivacaine 0.06 mg/cm height provided spinal anesthesia for cesarean delivery, with low occurrence of hypotension and vasopressor requirements, while ensuring excellent perioperative surgical anesthesia, as demonstrated by De Simone et al. (1995); these results are against our study, which supports a heavy marcaine dose of 0.05 mg/cm height as the lowest effective dose, with less hemodynamic instability .
A low dose of up to 0.05 mg/cm height heavy bupivacaine for cesarean sections under spinal anesthesia was found to be effective, as reported by Daniel and colleagues. These results are supported by our study, the heavy marcaine dose of 0.05 mg/cm height, as the lowest effective dose with the lowest haemodynamic instability .
A dose of 0.05 mg/cm height heavy bupivacaine is likely to reduce the incidence of hypotension caused by the spinal anesthesia, and possibly the severity of maternal effects resulting from it, but there was increased risk of pain during the operation, and increased usage of supplementary requirements, together with a slower onset and shorter duration of anesthesia, which was shown by Rucklidge. This result are against our study, which supports that heavy marcaine dose of 0.05 mg/cm height is an effective dose for cesarean section .
Finucane , suggested that spinal anesthesia in a cesarean section containing a 0.05 mg/cm heavy bupivacaine body height was associated with significantly lower occurence of hypotension, vasopressor requirements, and nausea than spinal anesthesia with heavy bupivacaine 0.08 mg/cm high.
Heavy bupivacaine with a dose of 0.06 mg/cm height leads to sufficient anesthesia and lower blood pressure and nausea, compared with 0.1 mg heavy bupivacaine/cm height, as indicated by Bendavid ; these results are against our study, which supports the heavy bupivacaine dose of 0.05 mg/cm height as the lowest effective dose with the lowest hemodynamic instability.
Arzola and Wieczorek stated that a low dose of heavy bupivacaine (0.05 mg/cm height) in spinal anesthesia lowers the efficacy of the anesthetic agent (high risk of anesthetic supplementation), despite the benefits of maternal side effects becoming lower in intensity (decreased blood pressure, nausea, and vomiting). These results are against our studies that support the heavy bupivacaine dose of 0.05 mg/cm height as an effective dose for cesarean delivery .
Carrie showed that the occurrence of an upper level block above T4 occurs more frequently with heavy bupivacaine 0.06 mg/cm height than those receiving heavy bupivacaine 0.05 mg/cm heights. The risk of severe arterial hypotension caused by the sympathetic blockade of the heart is greater in patients receiving bupivacaine 0.06 mg/cm height. These results are consistent with our study, which supports a heavy bupivacaine dose of 0.05 mg/cm height as the lowest effective dose with less circulatory instability .
| Conclusion|| |
The results of this study demonstrated that performing spinal anesthesia for short stature pregnant female individuals using 0.05 mg/cm height heavy bupivacaine showed marked benefit as regards adequate anesthesia and hemodynamic stability. This study has opened the ground for intensive research for finding the optimum dose of heavy bupivacaine to achieve adequate anesthesia for cesarian section with the least hemodynamic affection.
Financial support sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]