Comparison between Position Change after Low-Dose Spinal Anesthesia and Higher dose with Sitting Position in Elderly Patients: Block Characteristics, Hemodynamic Changes, and Complications.

BACKGROUND: Large numbers of patients are presenting for surgeries with aging-related pre-existing conditions that make them at higher risks of adverse outcomes. Hemodynamic instability due to high sympathetic nerve block largely limits the use of conventional dose spinal anesthesia in high risk elderly patients. AIMS AND
OBJECTIVES: We aimed to compare the hemodynamic stability and the block characteristics in low dose spinal anesthesia (5 mg) with immediate position change into supine position versus higher dose of spinal anesthesia (10 mg) with maintaining patient position in sitting position for 3 minutes after the block in elderly high risk population. SETTINGS AND
DESIGN: This study was a prospective randomized controlled double-blinded clinical study.
MATERIALS AND METHODS: This study was carried on 70 patients of American Society of Anesthesiologists physical status classes I, II, and III aged 50 years old and above, who were scheduled for elective knee and below knee orthopedic surgeries expected to last for 40-60 minutes under spinal anesthesia. Patients were randomly allocated into two groups: group (A) Sitting group n= 35 patients that received 10 mg hyperbaric bupivacaine 0.5% in 2 mL volume intrathecal at level lumbar (L4-5) in sitting position and remained in this position for 3 minutes before turning supine. And, group (B) Supine group n = 35 patients received 5 mg (low dose) intrathecal hyperbaric bupivacaine in 2 mL volume (1 mL hyperbaric bupivacaine 0.5% diluted with 1 ml sterile distilled water) at L4-5 in sitting position then turned supine immediately. The injection will be in the midline over 30 seconds by 25 gauge(G) Quincke needle. We measured the changes of mean arterial blood pressure, heart rate, O2 saturation and the incidence of hypotension and bradycardia intraoperatively as a primary outcome. Also, we measured the characteristics and the duration of the sensory and motor blocks, the duration required till return of bladder function and the satisfaction levels of both the patients and the surgeons as secondary outcomes. STATISTICAL ANALYSIS USED: Student's t-test and Chi-square test were used for analysis.
RESULTS: As regards hemodynamics, mean arterial blood pressure and heart rate were significantly lower in group A compared to group B; P-value <0.05, during the intraoperative period, while MABP and HR were significantly decreasing in group A during the initial intraoperative period at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min and 35 min, but in group B these parameters were statistically insignificant throughout the whole procedure P-value >0.05. As regards oxygen saturation, there were no significant differences between both groups or within the same group during the whole intraoperative period. Comparing sensory and motor blocks, sensory block was significantly higher and motor block was significantly dense in group A compared to group B during the first intraoperative period at 5 min, 10 min, 15 min, 20 min and 25 minutes. The recovery times from sensory and motor blocks were significantly longer in group A compared to group B (P-value <0.001). Also, the void recovery time was significantly longer in group A (129.29 ± 5.87 min) compared to group B (114.77 ± 8.24 min). In group B, patient satisfaction was significantly better (25 excellent/ 10 good) compared to group A (10 excellent/25 good). Also, surgeon satisfaction was statistically significantly better in group B (23 excellent/12 good) compared to group A (14 excellent/21 good). As regards side effects, in group A, 3 patients had to receive ephedrine due to significant reduction in MABP while no patients in group B had significant hypotension or bradycardia throughout the intra operative period.
CONCLUSION: We concluded that the use of small dose of heavy bupivacaine 0.5% (5 mg) with immediate patient position changing to supine position provided good spinal block characteristics in elderly population without any hemodynamic side effects, also with better patient and surgeon satisfaction levels compared to higher doses of heavy bupivacaine (10 mg) even if we maintained patient position in the sitting position for 3 min after the block. Copyright:

INTRODUCTION

Rationale and background

As the average life expectancy has been recently increased due to advancement in medical service practice and the upsurge of consideration on health conditions, the aging population started to rapidly increase. It is required to properly consider rewards and drawbacks between general and regional anesthesia, and to provide an understanding of anatomy, pharmacological changes of medicine, and physiological changes of old age in order to reduce the frequency of complications or after effects of surgery or anesthesia, since an increase of aging population obliges as a major risk factor for increasing the number of patients suffering from chronic diseases and perioperative mortality.[1] Spinal anesthesia uses only a small amount of local anesthetics related to the one needed for epidural anesthesia and requires relatively simple procedures and fast anesthetic onset effect. In addition, the rate of occurrence of thromboembolism and cardiovascular complications after surgery is reduced during spinal compared to general anesthesia and the amount of blood transfusion and hemorrhage in the perioperative period, leading to a decrease in the rate of pneumonia and respiratory failure in cases of patients suffering from chronic lung diseases.[2] Therefore, in general cases, spinal anesthesia is most likely selected for orthopedic surgery of lower limb for elderly patients. In addition, this frequently causes hypotension and bradycardia,[3] such cardiovascular changes serve as a major reason for increasing the rate of morbidity and mortality. Therefore, it is required to consider a safe method for esthesia that can maintain perioperative and postoperative hemodynamic stability.[4]

Aim of the study

The primary outcome of this study was to compare the hemodynamic changes of elderly patients who remain in sitting position for 3 min after 10 mg intrathecal hyperbaric bupivacaine compared to patients who were placed in supine position immediately after giving a low dose of bupivacaine (5 mg). The secondary outcomes were to compare the level of sensory and motor blocks, Bromage scale, patient and surgeon satisfaction as well as the occurrence of complications between the two groups.

MATERIALS AND METHODS

After Ethical Committee approval of the Fayoum University Hospitals and written informed consents from the patients were taken, 70 patients of the American Society of Anesthesiologists physical status classes I, II, and III aged 50 years old and above, who were scheduled for elective knee and below knee orthopedic surgeries expected to the last for 40–60 min under spinal anesthesia, were included in this prospective double-blinded study which was conducted between March 2018 and April 2019. Exclusion criteria were patients with other neurological diseases, spine abnormalities, absolute, and relative contraindications to spinal anesthesia as patients suffering from intracranial hypertension, major bleeding disorder, patients on anticoagulant, local infection, dementia, and allergic reaction to local anesthetics. Patients received no preoperative sedation, and they were off oral fluids for 2 h and for 8 h for solid food preoperatively. On arrival to the anesthetic room, two large bore intravenous (i.v.) cannulas were inserted, and ringer lactate 8 mL/kg was given as a preload over 30 min when appropriate and maintained intraoperatively with a rate of 8 mL.kg-1.h-1. All patients received oxygen (4 L.min-1) using a face mask during the procedure; standard routine monitoring was applied including electrocardiogram, noninvasive blood pressure, and pulse oximetry that will be continued intraoperatively. Patients were allocated to either study groups using a randomized central computer-generated sequence and a sealed envelope assignment held by an investigator not involved with the clinical management or data collection, and they were randomly allocated into two groups as follows: Group (A) Sitting group n = 35 patients who received 10 mg hyperbaric bupivacaine 0.5% (Marcaine®, AstraZeneca, Sweden) in 2 mL volume intrathecal at level lumbar (L4–5) in sitting position and remained in this position for 3 min before turning supine. Moreover, Group (B) supine group n = 35 patients received 5 mg (low dose) intrathecal hyperbaric bupivacaine in 2 mL volume (1 mL hyperbaric bupivacaine 0.5% diluted with 1 mL sterile distilled water) at L4–5 in sitting position then turned supine immediately. The injection will be in the midline over 30 s by 25 gauge (G) Quincke needle. The study solution was prepared by another investigator and its content blinded to the anesthetist who administered it, the anesthesiologist who will collect the data will be unaware about any of the experimental groups. If adequate surgical anesthesia was not achieved, general anesthesia was performed, and patient was excluded from our study. Hypotension was defined as a systolic blood pressure dropped <90 mmHg or mean arterial blood pressure (MABP) was reduced 30% lower than the base line, and hence, ephedrine was given in 3 mg incremental doses until improvement. If heart rate (HR) was recorded lower than 50 beat/min, it was defined as bradycardia and 0.5 mg of atropine was given i.v..

Measured parameters

The mean arterial pressure, pulse rate, and oxygen saturation were recorded at 5-min intervals till the end of the procedures (primary outcome)

The rate of occurrence of hypotension, bradycardia who required the use of ephedrine and atropine (primary outcome)

The level of sensory block and motor blocks (secondary outcome). Five minutes after subarachnoid injection, patients were evaluated for 25 min, in 5-min intervals. Sensory block level was evaluated using the pin-prick test for both sides by using a 25G needle. Assessments of motor block were made immediately after the assessment of the analgesia, motor block level was assessed using the Bromage scale,[5] (0 = no motor block; 1 = hip blocked; 2 = hip, and knee blocked; and 3 = hip, knee, and foot blocked)

The durations of recovery from sensory and motor blocks were measured (secondary outcome). Duration of sensory block was defined as the time when the sensory blockage reached highest dermatomal level till recovery of S2 dermatome. Duration of motor block was defined as the time at which the Bromage scale was declined from score 3 to score 0

The duration required till the return of bladder function (ability to void urine without difficulty) was recorded and compared (secondary outcome)

The degree of satisfaction of the patients and the surgeons was compared between the two groups. Four grades will be classified: Excellent, good, fair, and poor. We evaluated the satisfaction of the surgeons immediately after the surgery and of the patients right before coming to the ward (secondary outcome).

Statistical analysis and sample size

Using PASS 11 and based on data from Mehta S et al. study,[6] it was calculated that group sample size of 23 patients per group achieved 81% power to detect a difference between the group proportions of 40% in the incidence of hypotension, The test statistic used is the two-sided Z test with pooled variance. The significance level of the test was targeted at 0.0500. The significance level actually achieved by this design is 0.0497. We choose our sample size to replace any missing data. The statistical analysis was performed using the standard SPSS software package version 21 (Chicago, IL, USA). Normally distributed numerical data are presented as a mean ± standard deviation and differences between groups were compared using the independent Student's t-test, and categorical variables were analyzed using the Chi-square test or Fisher's exact test and are presented as number (%). All P values are two-sided. Value of P < 0.05 is considered as statistically significant.

RESULTS

The demographic data of the two studied groups are summarized in Table 1, statistical analysis revealed nonsignificant differences between the two groups as regards age, sex distribution, height, weight, and duration of surgery. No patients were excluded after inclusion to the study. As regards hemodynamics, MABP and HR were significantly lower in Group A compared to that of Group B [Tables 2 and 3]; value of P < 0.05, during the intraoperative period, whereas MABP and HR were significantly decreasing in Group A during the initial intraoperative period at 5, 10, 15, 20, 25, 30 , and 35 min, but in Group B, these parameters were statistically insignificant throughout the whole procedure P > 0.05. As regards oxygen saturation, there were no significant differences between both groups or within the same group during the whole intraoperative period [Table 4]. Comparing sensory and motor blocks [Tables 5 and 6], sensory block was significantly higher and motor block was significantly dense in Group A compared to Group B during the first intraoperative period at 5, 10, 15, 20 , and 25 min. The recovery times from sensory and motor blocks were significantly longer in Group A compared to Group B (P < 0.001) [Table 7]. Furthermore, the void recovery time was significantly longer in Group A (129.29 ± 5.87 min) compared to Group B (114.77 ± 8.24 min) [Table 7]. In Group B, patient satisfaction was significantly better (25 excellent/10 good) compared to Group A (10 excellent/25 good). Furthermore, surgeon satisfaction was statistically significantly better in Group B (23 excellent/12 good) compared to Group A (14 excellent/21 good) [Table 7]. As regards side effects, in Group A, 3 patients had to receive ephedrine due to a significant reduction in MABP while no patients in Group B had significant hypotension or bradycardia throughout the intraoperative period.

Table 1

Demographic data

	Group A (n=35)	Group B (n=35)	P
Age (years)	55.18±10.9	56.76±8.69	0.501
Sex (male/female)	17/18	19/16	0.54
Height (cm)	165.12±10.3	169.57±8.6	0.2
Weight (kg)	69.59±9.9	69.14±9.36	0.847
Duration of surgery (min)	49.12±6.45	52.43±5.74	0.27

Data are presented as mean±SD or ratio of patients. P>0.05 is considered statistically nonsignificant. SD=Standard deviation

Table 2

Mean arterial blood pressure (mmHg)

	Group A (n=35)	Group B (n=35)	P
Preoperative	99.56±11.95	106.11±11.4	0.2
5 min	97.82±9.52	105.2±12.1	0.011*
P	<0.001**	0.185
10 min	95.6±8.7	103.5±10	0.001*
P	<0.001**	0.181
15 min	92.9±9.66	102.9±11.2	0.001*
P	<0.001**	0.84
20 min	89.47±11.08	102±6.86	<0.001*
P	<0.001**	0.377
25 min	87.65±10.4	100.6±12.48	<0.001*
P	<0.001**	0.187
30 min	84.12±8.63	100.86±18.3	<0.001*
P	0.004**	0.2
35 min	81.9±10.84	101.36±9.85	<0.001*
P	<0.001**	0.04
40 min	82.3±17.1	102.2±8	<0.001*
P	0.04	0.186
45 min	84.9±9.97	103.9±9	<0.001*
P	0.211	0.3
50 min	86.8±11.39	104.3±9.2	0.001*
P	0.3	0.66

Data are presented as mean±SD. *P<0.05 is considered statistically significant between the two groups, **P<0.05 is considered statistically significant compared to the data before in the same group. SD=Standard deviation

Table 3

Heart rate (beat/min)

	Group A (n=35)	Group B (n=35)	P
Preoperative	107.85±15.25	109.97±13.9	0.548
5 min	100.5±12.8	107.11±13.82	0.045*
P	0.001**	0.292
10 min	96.62±11.35	106.63±13.23	0.032*
P	0.02**	0.224
15 min	93.15±11.16	106±10.225	<0.001*
P	0.03**	0.292
20 min	90.12±7.1	104.4±11	<0.001*
P	0.021**	0.234
25 min	87.88±10.98	102.37±11.1	<0.001*
P	0.04**	0.142
30 min	84.35±13.66	101.28±8.2	0.014*
P	0.041**	0.31
35 min	80.1±10.69	101.22±6.97	<0.001*
P	0.04**	0.96
40 min	82.58±10.2	103.3±10.13	<0.001*
P	0.212	0.155
45 min	84.47±7.24	104.3±7.23	0.012*
P	0.210	0.495
50 min	86.3±10.37	107.83±9.86	0.014*
P	0.204	0.21

Data are presented as mean±SD. *P<0.05 is considered statistically significant between the two groups, **P<0.05 is considered statistically significant compared to the data before in the same group. SD=Standard deviation

Table 4

O2 saturation(%)

	Group A (n=35)	Group B (n=35)	P
Preoperative	98.4±2.16	98.7±0.4	0.142
5 m	97.86±1.99	98.49±051	0.153
10 m	98.2±0.77	98.4±0.5	0.158
15 m	97.74±0.83	98.1±0.56	0.43
20 m	97.9±0.75	98.2±0.58	0.08
25 m	97.6±0.82	98.26±0.66	0.07
30 m	98±0.43	97.94±2.1	0.883
35 m	98.2±0.79	98.3±0.789	0.569
40 m	97.88±1.6	99±1	0.149
45 m	98.2±0.68	98.4±0.6	0.158
50 m	98.35±0.85	98.3±0.67	0.835

Data are presented as mean±SD. P>0.05 is considered statistically not significant between the two groups. SD=Standard deviation. SD=Standard deviation

Table 5

Bromage score

	Group A (n=35)	Group B (n=35)	P
5 min	2 (2-3)	1 (1-2)	0.01*
10 min	3 (2-3)	2 (2-3)	0.021*
15 min	3 (2-3)	2 (2-3)	0.0018*
20 min	3 (3-3)	3 (2-3)	0.0068*
25 min	3 (3-3)	3 (2-3)	0.006*

Data are presented as median (IQR). *P<0.05 is considered statistically significant between the two groups. IQR=Interquartile range

Table 6

Level of sensory block

	Group A (n=35)	Group B (n=35)	P
5 min	T10 (T10-T12)	T11 (T11-L1)	<0.001*
10 min	T9 (T9-T11)	T10 (T10-12)	<0.001*
15 min	T8 (T8-T11)	T10 (T10-T11)	<0.001*
20 min	T8 (T8-T10)	T9 (T9- T11)	<0.001*
25 min	T8 (T8-T11)	T9 (T9-T12)	<0.001*

Data are presented as median (IQR). *P<0.05 is considered statistically significant between the two groups. IQR=Interquartile range

Table 7

SB recovery time, MB recovery time, void recovery time, patient satisfaction level, surgeon satisfaction level

	Group A (n=35)	Group B (n=35)	P
SB recovery time (min)	111.88±5.24	103.2±6.1	<0.001*
MB recovery time (min)	94.4±4.16	86.37±12.92	0.001*
Void recovery time (min)	129.29±5.87	114.77±8.24	<0.001*
Patient satisfaction
Excellent	10	25	0.001*
Good	25	10
Surgeon satisfaction
Excellent	14	23	<0.001*
Good	21	12

Data are presented as mean±SD or number of patients. *P<0.05 is considered statistically significant between the two groups. SD=Standard deviation, SB=Sensory block, MB=Motor block

DISCUSSION

Surgeries done with spinal anesthesia have distinct advantages of decreased blood loss, minimal perioperative cardiac ischemic incidents, postoperative hypoxic episodes, arterial venous thrombosis, and better postoperative pain control.[7] A change in cardiovascular physiology associated with aging decreases cardiovascular reserve and may predispose elderly patients to hemodynamic instability more over the high incidence of coronary artery diseases that render those patients more liable to cardiac ischemia due to hypotension.[8] This cardiovascular risk increases with the use of spinal anesthesia, especially in the elderly population. There is considerable controversy over the use of vasopressors to treat the hypotension of spinal anesthesia; furthermore, ephedrine treatment of hypotension increases HR.[910] Furthermore, excessive fluid loading may lead to more complications such as fluid overload and is, therefore, better to be avoided.[9] The increase of the age and the high level of the sensory block are the main reasons for hypotension after spinal anesthesia. Hypotension occurred due to the sympathetic nerve block that is 2–4 segments higher than the level of sensory block. According to Lee et al.,[11] the ratio of occurrence of hypotension on the elderly patients aged more than 70 were 48%, which turned out to be significantly higher than the patients aged <60 by 4.2% after using 7 mg of 0.5% heavy bupivacaine. Therefore, the level of the sympathetic block is important in our practice and it is important not to unnecessarily increase the height of the block during spinal anesthesia in those elderly patients. The advantage of using hyperbaric local anesthetic solutions is the flexibility of controlling the level with posture. However, it is still controversial in terms of period needed for seating position to restrict the level of sympathetic block. For the purpose of minimizing the degree of the sympathetic block, especially in those high-risk elderly patients, many studies tried to use different techniques and even injecting different intrathecal drugs to achieve this. In 2014, Singh et al. studied the use of unilateral intrathecal block with low-dose heavy bupivacaine 0.5% (7.5 mg) in lower limb orthopedic surgeries, but they found that the unilateral block was obtained only in 75% of the patients which became only 65% on turning the patients into supine position which led to hypotension in some patients.[12] In 2015, in the study done by Saber and El Metainy,[13] they concluded the efficiency and better hemodynamic stability with the use of continuous intrathecal block (CSA) in lower limb orthopedic surgeries compared to low-dose intrathecal heavy bupivacaine 0.5% (7.5 mg), but still CSA carries the risk of significant postoperative dural puncture headache as well as infection due to the presence of intrathecal catheter, especially in those high-risk elderly patients. The study demonstrates that the use of small dose (5 mg) of heavy bupivacaine 0.5% in spinal anesthesia with immediate position changing (supine) provides hemodynamic stability without episodes of severe hypotension or bradycardia and provides also sufficient anesthesia for lower limb fractures repair in the elderly compared to higher intrathecal doses (10 mg) even if we maintain the sitting position for 3 min. In concordance with our results, Kararmaz et al.[14] studied the effect of low-dose bupivacaine (only 4 mg) in spinal anesthesia for trans-urethral resection of the prostate and they concluded that it provided sufficient block for the surgery without any hemodynamic complications, but they had to add 25 μg of fentanyl intrathecally that caused some adverse effects in the form of pruritis, nausea, and vomiting which we did not use in our study as we used larger bupivacaine dose (5 mg) with immediate patient's position change (supine). Kim et al.,[15] who compared the effect of low-dose intrathecal heavy bupivacaine given in lateral decubitus position then turning the patients immediately to supine position compared to the effect of the same dose given in sitting position with maintaining this sitting position for 2 min after block, and they found that the sensory block and the episodes of hypotension and bradycardia were significantly higher in the supine position group compared to the sitting group which is in contrast to our findings. This may be attributed to the fact that in our study; in the sitting group, we injected larger heavy bupivacaine dose (10 mg) while Kim et al. injected only 6.5 mg heavy bupivacaine in their sitting group so this caused higher sensory block level and more episodes of hypotension and bradycardia in our setting group than those of the sitting group of Kim et al. Also, we gave smaller intrathecal bupivacaine dose (5 mg) in our supine position group than the dose that Kim et al. used in their supine position group (6.5 mg) so in our supine group the episodes of hypotension and bradycardia were less than those of the supine group of Kim et al.

CONCLUSION

We believe that the use of small dose of heavy bupivacaine 0.5% (5 mg) with immediate patient position changing to supine position provides good spinal block characteristics in elderly population without any hemodynamic side effects, also with better patient and surgeon satisfaction levels compared to higher doses of heavy bupivacaine (10 mg) even if we maintain patient position in the sitting position for 3 min after the block.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.