Lumbar laminectomy is the one of the most commonly performed spine surgery now a days. Traditionally general anaesthesia (GA) is preferred and widely used anaesthesia technique for lumbar spine surgery due to a variety of factors, including greater patient acceptance, able to extend duration for long surgeries and secured airway in the prone position.[1][2] But in GA, along with the increased stress response of laryngoscopy and intubation, there is also increase blood loss, duration of surgery and requirement for blood transfusion [3].

Among regional anaesthesia, spinal anaesthesia (SA) and epidural anaesthesia are the alternative anaesthesia techniques for lumbar spine surgeries. Spinal anaesthesia has several benefits noted in the literature, including rapid onset, decreased operative and anaesthesia time, less intra-operative blood loss etc. [4][5][6] The shorter duration of anaesthesia and lesser required assistance for positioning the patients are other advantages of SA. There are several studies comparing various perioperative outcome parameters in spinal and general anaesthesia in lumbar spine surgeries.

India is still a developing nation with an overall lack of health care that necessitates the use of anaesthesia techniques that are not only safe and cost-effective but also cause less peri-operative morbidity and early discharge from the PACU. Spinal anaesthesia can prove to be such a reliable technique that may reduce the burden not only on the health care system but also on cost-effectiveness for patients. Keeping this aspect in our mind, we planned a study with a aim to compare various perioperative outcome variable between SA and GA in cases of single or double-level elective lumbar laminectomy surgeries.

This randomized prospective comparative study was conducted in the Department of Anaesthesiology, Dr. S. N. Medical College, Jodhpur from August 2021 to January 2022 after taking approval of institutional ethics committee approval (SNMC/IEC/2021/plan/468). The study enrolled the patients undergoing one or two-level elective lumbar laminectomy for diagnosed disc herniation (DH) or lumbar canal stenosis (LCS). In the study total 60 patients with American Society of Anaesthesiologists physical status (ASA PS) 1-2, and aged 18-60 years were included. Patients with an anticipated difficult airway, contra-indications of spinal anaesthesia, diagnosed herniated lumbar disc of level >2 for elective surgery, long term history of neuropathic pain at the operation site etc were excluded.

Patients were randomized into two groups, Group S and Group G; with 30 patients in each group. In group S, patients were given spinal anaesthesia and in group G, patients were given general anaesthesia.

Detailed pre-anaesthetic evaluation for all the subjects was done which included general condition, history, physical examination, and ASA- PS grading. All the basic investigations including complete blood profile, RFT, coagulation profile, serum electrolytes, urine analysis, HIV, HBsAg, Chest X-ray PA view, and ECG were done before surgery. The night before surgery, all subjects were given orally omeprazole 20 mg and alprazolam 0.25 mg and advised to remain nil by mouth (NBM) as per fasting guidelines.

In the pre-operative area, the patient was identified and reviewed, consent was checked and NBM status was confirmed. All vital parameters were attached and baseline vitals including HR, BP and SpO2 were recorded. Intravenous (IV) line with 18G cannula was secured. Then, randomization was done and patients were allocated to either of spinal or general anaesthesia group.

In the group G, once the patient was in operating room (OR) all vitals’ parameters were attached, and iv premedication i.e., inj. midazolam 2 mg, inj. ondansetron 4mg and inj. glycopyrrolate 0.2mg was given. Patients were pre-oxygenated with 100% oxygen on bag and mask and inj. lidocaine (1.5 mg/kg), and inj. fentanyl (2 μg/kg) were given. Patients were induced with inj. propofol (2 mg/kg), and after giving inj. atracurium (0.5 mg/kg), patients were intubated with a cuffed endotracheal tube. Balanced anaesthesia was maintained with sevoflurane and intermittently inj. atracurium 0.1mg/kg. After the completion of surgery, the anaesthetic drugs were discontinued and neuromuscular blockade was reversed. After adequate spontaneous respiration, extubation done and shifted to PACU.

In the group S, once the patients in the OR, vitals’ parameters were attached and the patients were coloaded with 7 ml/kg Lactated Ringer's solution over 10-15 minutes. The patients were placed into a sitting position, prepared and draped. Spinal anaesthesia was performed using a 25-gauge Quincke spinal needle at one or two levels of interspace above the surgical site. After observing spinal fluid, with 3ml 0.5% heavy bupivacaine combined with 25 μg fentanyl were administered into the intrathecal space and patients were placed in the supine position. Once the level of the spinal block (sensory block up to T6 and motor block as per modified Bromage score 1) was established in next five to ten minutes, patients were placed in the prone position. If even after 15 minutes of spinal anaesthesia, adequate level of sensory and motor block was not established then it was considered as spinal block failure and had to be converted into GA and excluded from the study. Oxygen at 4L/min via face mask was administered afterward. During surgery, patient was sedated with intravenous propofol infusion at the rate of 25 to 50 μg/kg/min.

The vital parameters i.e., HR, SBP, DBP, MBP, and SpO2 were monitored. If the patients had bradycardia (HR less than 50 per minute) inj. atropine 0.6mg iv or if hypotension (SBP less than 90 mmHg) inj. ephedrine 5mg was administered. If any patient had nausea or vomiting, inj. metoclopramide 0.1mg/kg iv, if headache inj. paracetamol 15 mg/kg iv infusion and if pain (VAS score >4) then inj. tramadol 2 mg/ kg iv (after giving inj. ondansetron 0.15 mg/kg iv) were given respectively.

Observations assessed were the following:

• Anaesthesia duration.
• Operative time.
• Haemodynamic parameters- HR, SBP, DBP, MAP and SpO₂ for every 5 minutes for the first half an hour (beginning from the spinal block), then every 15 minutes till 240 minutes (4 hours), then every 30 minutes till 360 minutes (6 hours) and then every 60 minutes till 480 minutes (8 hours).
• Blood loss as well as total operative fluid requirements (including fluid given immediately before induction of anaesthesia).
• Surgeon’s and patient satisfaction using the Likert scale [7] (a uni-dimensional psychometric scale that measures respondent’s attitude, score ranging from 1-4) where 1=Excellent, 2=Good, 3=Fair and 4=Poor
• Perioperative side effects– Bradycardia, hypotension, nausea or vomiting, headache, pain, urinary retention, and shivering were noted.
• PACU time
• Total analgesia dose given in first 24 hours

The primary objective was to compare anaesthesia duration between both the groups. Secondary objectives were to compare blood loss, hemodynamic stability, operative time, surgeon satisfaction, patient satisfaction, PACU time, total analgesic dose given in first 24 hours and duration of hospital stay between both the groups.

Statical Analysis-

Sample size is calculated at alpha error 0.05 and study power 90% using the formula for hypothesis testing for two population mean.

Sample size was calculated using below formula: - 

n = ([2×(Z(1-α/2) )+ Z(1-β) )]²× σ²)/[(μ1-μ2)] ²  .

The minimum sample size calculated is 21 but due to anticipated dropouts during the study sample size for each group was taken as 30. Hence, total sample size for the study was taken as 60.

Data was entered into MS EXCEL and analysed using SPSS version 17.  Categorical (qualitative) data was presented as numbers (proportion) and compared using the chi-square test. The continuous variable (quantitative) was presented as mean±SD and compared using t–test or ANOVA as per need P value < 0.05 was considered as statistically significant.

A total of 60 patients were included out of which there was zero dropout and no spinal failure occurred. The distribution of age, gender, weight, height, BMI, ASA- PS grading and diagnosis between the two groups were comparable. Along with the above parameters, the surgeries performed on one level and two levels were also comparable in group S and group G. In both groups, L4-5 was the most common level involved. [Table 1]

Table -1 demographic variables

The primary objective of our study was anaesthesia duration. The mean anaesthesia duration was 111.4± 17.9 mins in group S as compared to157.6± 16.5 mins in group G with P value of <0.0001 the difference is statistically highly significant. The other timings like operative time, mean time from entering OR to incision, and mean time from placement of surgical dressing until patient exits from the OR were found to be statistically significant (P <0.0001) [Table 2].

Table 2: Comparison Of Variables Between Both the Groups

Mean surgical blood loss calculated in group S was 72.23± 18.56 ml whereas in group G it was 139.33± 31.72 ml with P-value <0.0001. [Table 2]. Using the Likert scale, surgeon satisfaction was found to be better in group S as compared to group G (P = 0.006). [Graph 1].

Graph- 1: Surgeon Satisfaction wise distribution of all patients

 Similarly, patients’ satisfaction was also found to be better in group S in comparison to group G (P value=0.023). [Graph 2] 

The incidence of variations in haemodynamic parameters was seen less in group S as compared to group G, although the variations were not statistically significant. [Table 3]

Table 3 : Haemodynamic Parameters

However, in group S in the first 5 minutes of spinal anaesthesia patients had an increase in HR or decrease in BP which was not significant. Out of 30 patients, the incidence of bradycardia in group S was only in 3 (10%) patients vs 5 (16.67%) patients in group G (P value=0.706). Similarly, in group S only 5 (16.67%) patients developed hypotension vs. 8 (26.67%) patients in group G (P value=0.532). Regarding hypertension, only 2(6.67%) patients in group S versus 4 (13.33%) patients in group G developed it (P value=0.67).  Similarly, the incidence of tachycardia only 6 (20%) patients group S versus 8 (26.67%) patients in group G (P value= 0.761). 

Among postoperative complications, the incidence of nausea/vomiting and shivering were comparable less in group S whereas urinary retention incidence were comparable more in group S, but the difference is statistically insignificant between both the groups. [Graph 3]

The mean duration of stay in PACU was significantly less in group S (223.7±13.02 mins) as compared to group G (307.73±26.97 mins) with P value<0.0001. Similarly, the mean duration of hospital stay (in days) in group S was 1.88±0.38 vs 2.46±0.41 in group G. The difference is statistically significant with P value <0.0001 [Table 2] The mean total analgesic dose required in the first 24 hours in group S was 2.13±0.34 and in group G was 2.36±0.49, with P value 0.037, hence statistically significant.

In the current global scenario, lumbar spine surgeries especially lumbar laminectomy, are the most common surgeries performed among all spine surgeries. Although both GA and SA are reliable and safe techniques, they can be used interchangeably for performing less extensive lumbar spine surgeries. Both have their advantages and disadvantages that may exert distinctive effects on peri-operative outcomes. [8]

In our study, the primary objective, the mean anaesthesia duration was significantly less in SA than GA because the mean time taken from entering OR to incision and mean time from placement of surgical dressing until patient exits from the OR during SA were significantly less. The reason behind it is that after giving SA it is easier and faster to prone an awake patient as the patient can move freely and adjust according to the position but during GA more time is taken to orally intubate, then prone the paralyzed patient carefully and also supine the patient at the end of surgery all while avoiding pressure necrosis and nerve injuries and finally extubate. The lesser anaesthesia duration leads to less time for the patient to stay inside the OR thus decreasing morbidity, and peri-operative complications, hence reducing the burden on our healthcare system in terms of both time and cost. These results are also consistent with a study conducted by Sharif Ahmed Jonayed et al., [9] who conducted a cross-sectional analytical study on 64 patients and discussed that in GA more time is required to intubate, extubate, and transfer the patient to the post-operative room which is not required in SA. Morris MT et al., [10] in their retrospective chart review and Sekerak et al., [11] observed that under GA time required to assess patient responsiveness and respiratory function before extubation leads to a net increase in anaesthesia time. Sarkar et al., [12] in their retrospective study of 239 cases observed that in GA considerable time was needed for intubation.

Our study results showed that operative time during SA was also significantly less than in GA as the mean surgical blood loss calculated during SA (72.23± 18.56 ml) was significantly less than during GA (139.33± 31.72 ml) due to less distension of epidural veins caused by negative intra-thoracic pressure created during spontaneous ventilation which led to better view of surgical field, thus higher surgeon’s satisfaction. This finding comes in line with various studies in the literature [8,13,14]. However, Agarwal P et al., [15] observed lesser blood loss for SA since sympathetic blockade tends to reduce heart rate and arterial and venous pressure. One of the key findings of the retrospective chart review conducted by Morris MT [10] et al., was also shorter operative and recovery times. Conversely, Sadrolsadat et al., [16] found no difference in the volume of intra-operative blood loss between SA and GA and proposed the mechanism as a drop in systemic vascular resistance after SA. Also, Kahveci K et al., [17] and Dashtbani M et al., [18] found that the duration of surgery and blood loss did not differ significantly between the two groups. Lessing et al., [19] in his study observed that mean operating time did not differ significantly but estimated blood loss did. Attari MA [9] showed higher surgeon satisfaction in the SA group owing to less blood loss and more haemodynamic stability. Surgeon satisfaction was however higher in the GA group in a study done by Sadrolsadat H [16)]. Patient satisfaction was better in spinal anaesthesia, likely due to fewer post-operative complications and analgesia requirements along with earlier discharge from the hospital as compared to the patients in general anaesthesia. This finding is in concordance with the study conducted by Hassi et al [20] and Attari MA et al [9]. Both studies showed that patient satisfaction was high with a low level of complications in SA with a P value <0.05.

We observed that although haemodynamic stability was higher in patients under spinal anaesthesia the difference between both groups was not significant. Finsterwald M et al [21] showed greater haemodynamic stability with less vasopressor and volume requirement in the SA group despite the fact, that this group included high-risk patients compared to the healthier GA group.

Postoperative side effects or complications seen were PONV, shivering, and urinary retention. However, urinary retention is a common complication of spinal anaesthesia and was seen more in SA cases but the difference between all the complications was not substantially significant between both the groups which were also observed by Jellish W Scott et al. [22]

Our study shows that the mean duration of stay in PACU was significantly less in group S as compared to group G. It was mainly because of early recovery and fewer postoperative complications in cases of spinal anaesthesia. This finding is in concordance with the study conducted by Sharif Ahmed Jonayed et al [9]. Contradictory to our finding, Kahveci K et al [17] in their study found comparative longer PACU stay in patients in the SA. According to them, the reason for the longer PACU stay of SA patients was their discharge until full motor/sensory recovery was observed. Sadrolsadat et al [16] did not observe a significant difference in the duration of PACU stay between patients who received SA and GA. The mean duration of hospital stay (in days) in group S was also less than in group G. It was mainly due to less postoperative analgesia requirement and early mobilization due to fewer perioperative complications. This finding is in line with a study conducted by Kahveci K et al [17]. Conversely, Sharif Ahmed Jonayed et al [9] found that the duration of hospitalization was less for patients with SA than GA but the difference was insignificant.

The mean number of times the total analgesic dose given in the first 24 hours was less in patients received SA than GA. The reduced pain response in SA might be due to inhibition of nociceptive pathways and reduced levels of stress response in the patients. Similar findings are shown by several studies in the literature. [7,9,17]

The limitations of our study were that it was conducted in a single center hospital thus, results cannot be generalized to the population of other countries. Also, the effects of the drugs on geriatric patients and patients with other comorbidities like cardiovascular, renal, and pulmonary systems were not inferred and need further study.

We conclude that outcomes of spinal anaesthesia in terms of peri-operative variables when compared to general anaesthesia are significantly better. Thus, we can safely and reliably use spinal anaesthesia as an anaesthetic technique in cases of one or two-level elective lumbar laminectomies.

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