Effects of different anesthetic techniques on neutrophil lymphocyte ratio and monocyte lymphocyte ratio in patients undergoing major non-cardiac surgery: A prospective, single-blind, randomized study

Abstract

Background: 

Various surgical and anesthetic techniques can produce stress. This study aimed to see the changes in neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) in patients undergoing major surgery at different time points.

Materials and Methods: 

A prospective randomized controlled single blinded study was conducted involving 300 patients, scheduled for elective non-cardiac surgeries, randomly grouped into Group 1 (general anesthesia [GA]), Group 2 (total intravenous anesthesia [TIVA]), and Group 3 (combined spinal and epidural [CSE]). Blood samples were collected for NLR and MLR (preoperatively, end-of-surgery, 6 and 24 h after surgery).

Results: 

There was an increase in NLR in all three groups and increase in mean NLR was highest in group GA at the end of the surgery, 6 and 24 h after surgery. The mean comparison of NLR at 6 and 24 h after surgery was also found to be significant when comparison was made between groups 1 and 2 (P = 0.001), and between groups 1 and 3 (P < 0.001); however, the difference was found to be insignificant when comparison was made between groups 2 and 3.

Conclusion: 

The mean comparison of NLR at 24 h after surgery was found to be significant when comparison was made between GA and TIVA, GA and CSE; however, the difference was insignificant between-TIVA and CSE groups. Highest rise in the mean NLR 24 h after surgery was found in patients who underwent surgeries under GA than TIVA followed by neuraxial blockade.

Introduction

Neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) are basic inflammatory markers that are inexpensive, easy to obtain, and easy to perform.^[1] The NLR has been extensively studied for a variety of medical conditions, including ischemic stroke, major cardiac events, cerebral hemorrhage, sepsis, and infectious disease, and has been proven to relate to outcome and predict disease course.^[2] The migration of activated lymphocytes to inflammatory tissues, combined with increased lymphocyte death, results in a drop in lymphocyte numbers.^[2-5]

The human body’s immune system is prone to alterations as a result of various anesthetic procedures and surgical stress.^[6-9] The patient’s age, general health status during surgery, blood transfusion, and drugs used are all linked to changes in the body’s general physiological reactions, which in turn reflect immune system changes. Several previous research works have shown that variations in the quantity of peripheral blood cells can indicate the body’s inflammatory response.^[10]

Although different methods of study are available, the NLR has been proposed as a simple and less expensive approach of assessing neuroendocrine responses than the more expensive C-reactive protein, tumor necrosis factor, interleukin-6, cortisol levels, and leptin levels. As a result, measuring NLR and MLR after various anesthetic procedures may be useful for assessing various inflammatory responses, infection, and prognosis. The use of various anesthetic procedures and their impact on neuroendocrine changes that could influence NLR are mainly unknown.^[11] This study was conducted to evaluate the effects of different anesthetic procedures on NLR and MLR in patients undergoing major non-cardiac surgery.

Materials and Methods

After obtaining approval from the ethical committee and informed consent from the patients, an observational, randomized, prospective, single blinded, analytical study was conducted in the Department of Anesthesia in All India Institute of Medical Sciences, Rishikesh. The study was enrolled in the Clinical Trials Registry (CTRI/2020/07/026760, dated: July 24, 2020) involving 300 patients aged 18–70 years classified the American Society of the Anesthesiologists grades I and II, and who were scheduled for elective noncardiac surgery. The study excluded patients with any contraindication to spinal anesthesia, general anesthesia, surgery in which there was a conversion of anesthesia technique, patients with existing acute infection, sepsis, on recent chemotherapy, chronic treatment with steroids or immunosuppressants, with endocrine diseases, electrolyte imbalance, hepatic and renal dysfunction, morbidly obese, have autoimmune disorders, and underwent blood transfusion in the past 7 days. All subjects provided written informed consent before inclusion to this study.

Participants were assigned randomly and evenly into one of the three groups: Group 1 (GA, those who received general, inhalational anesthesia), Group 2 (TIVA, total intravenous anesthesia), or Group 3 (CSE, combined spinal-epidural or central neuraxial blockade). The randomization was made by a computer-generated random table, and allocation concealment was done via a sequentially numbered sealed envelope technique.

Routine preoperative evaluation and medications, as well as American society of anaesthesiologists standard monitoring were applied. In Group 1, the patients were induced using 2–4 mg/kg propofol, 3 µg/kg fentanyl, air/oxygen mixture, and sevoflurane was used to maintain the bispectral index (BIS) of 40–60. In Group 2, the patients received a loading dose of 2 mg/kg of propofol and the depth of anesthesia was assessed by the loss of eyelash reflex and BIS score between 40 and 60. If both the conditions were not obtained with the initial dose of propofol, an incremental dose of propofol 0.5 mg/kg every minute, till the condition were achieved. A manual infusion of 15 mg/kg/h propofol was continued for the next 15 min, 11 mg/kg/h for 30 min, and 10 m/kg/h for 60 min and finally maintained at 9 mg/kg/h for the rest of anesthesia. At any point of time if the BIS score went above 60 a bolus of propofol 0.5 mg over 10 s was administered additionally. In Group 3, the CSE was performed under aseptic technique by placing a needle between lumbar vertebra L2–L5 for hip surgery and lower extremity, lower thoracic T6–T8 for obstetric analgesia, colectomy anterior resection and for upper abdominal surgery and thoracic surgery T2–T6 and injecting medication into the epidural space (for epidural anesthesia). Epidural anesthesia comprised bupivacaine or lidocaine in combination with fentanyl. Spinal anesthesia was performed at L2–L3 or L3–L4 with a 25-Gauge Quincke Spinal needle with the patient in seated position. Spinal anesthesia consisted of appropriate dose of hyperbaric bupivacaine 0.5% (2 mL) in combination with Fentanyl 25 µg.

Outcome parameters included NLR and MLR collected from blood sample report preoperatively at 24 h, end of the surgery, 6 and 24 h after end of the surgery, demographic parameters, duration of surgery, blood loss, urine output and fluid requirement, any post op complications till 24 h were also recorded [Figure 1].

Figure 1:: Sequence of conduct of study

The statistical test was conducted on SPSS statistical software suite (IBM Corp., Armonk, New York, IBM SPSS statistics for windows, version 21.0) Continuous date was presented as mean (SD) or median (interquartile range). Discrete number were taken as percentage and or proportions. χ² test was used to evaluate the association between categorical variables. Data were checked for normality using Kolmogorov–Smirnov and Shapiro–Wilk tests. One-way analysis of variance or Kruskal–Wallis test was used to compare mean difference between groups depending on the fulfilment of normality assumption for continuous variables and post hoc analysis was done. P value <0.05 was considered as significant.

Results

The mean age, sex, American society of anaesthesiologists classification, mean weight, mean height, mean body mass index, previous anesthesia exposure were comparable between the three groups [Table 1]. The other surgical characteristics including the types of surgery duration of surgery, and blood loss in all the three groups were comparable at the baseline among the three groups.

Table 1:: Demographic and surgical parameters in three groups (presented either as mean and standard deviation (SD) or n (%))

The mean comparison of NLR between groups 1 and 2 was significant (P = 0.011) at the end of surgery; it was also significant when comparison was made between groups 1 versus 3 (P < 0.001) and between groups 2 versus 3 (P = 0.007). The mean comparison of NLR at 6 h after surgery was also found significant when comparison was made between groups 1 versus 2 (P = 0.001), and between groups 1 versus 3 (P < 0.001), however, the difference was found insignificant when comparison was made between groups 2 versus 3 (P = 0.962). The mean comparison of NLR at 24 h after surgery was also found significant when comparison was made between groups 1 versus 2 (P < 0.001), and between groups 1 versus 3 (P 0.001); although, the difference was found insignificant when comparison was made between groups 2 versus 3 (P = 0.051).

The increase in mean NLR was seen to be highest in group inhalational GA when compared at end of the surgery, 6 and 24 h after surgery. On further comparison between the intergroup a significant difference was seen on comparison between groups 1 and group 2, at end of surgery till 24 h post-surgery. Significant difference was also seen in intergroup comparison of 1 versus 3 at end of surgery till 24-h post-surgery. In inter group comparison of 2 versus 3 significant difference was seen at end of surgery; however, no difference was found at 6- and 24-h post-surgery [Table 2 and Figure 2A].

Table 2:: Neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) at different time point in three groups (presented in mean and standard deviation)

Figure 2:: (A) Line graph of NLR comparison at different time intervals in three groups. (B) Line graph of MLR comparison at different time intervals in three groups

The MLR was comparable in all the three groups at baseline and there was an increase in MLR in all three groups; however, no significant differences were seen at the end of the surgery in all the three groups but significant difference was seen at 6 h after surgery (P = 0.003) and 24 h after surgery (P < 0.001). On post-hoc analysis in intergroup analysis of difference, significant difference was found between groups 2 and 3 at 6 h after surgery (P = 0.001) and at 24 h (P < 0.001) and also when compared between groups 1 versus 3 after 24 after surgery (P < 0.001), as seen in Figure 2B. There was no significant difference in occurrence of nausea, fever, and headache in the immediate postoperative period with different anesthetic techniques [Table 3].

Table 3:: Incidence of nausea, fever and headache in up to 24 h postoperative period

Discussion

The release of neuroendocrine hormones and cytokines occurs as a result of activation of neuroendocrine system due to anesthesia and surgery.^[3] In the postoperative period, an increase in total leucocyte count count and a reduction in the lymphocyte count can increase the chance of infection. NLR and MLR are considered as simple markers in peripheral blood smear to assess the inflammatory response and physiological stress during perioperative period. NLR is influenced by the various anesthetic techniques thereby modulating the inflammatory response and surgical response.^[12]

In the present study, it was seen that the effects of different anesthetic techniques on NLR post operatively were seen to have significant difference (P-value < 0.05) there was an increase in NLR in group 1 followed by group 2 and group 3. On further sub analysis in comparison to time shows that the NLR was increased more after 24 h of surgery in group 1 (GA) in comparison to group 2 (TIVA) and group 3 (neuraxial blockade). The current study’s findings are consistent with those of previous studies in which the authors have studied the effects of different anesthetic techniques on NLR after laparoscopic-assisted vaginal hysterectomy, randomly assigning forty patients to two groups: pulse rate receiving TIVA with propofol and remifentanil and group S receiving inhalation anesthesia with sevoflurane. They observed that both groups had a rise in NLR at the end of the procedure at all time points. The NLR in group pulse rate was significantly lower than in group S at T3 and at several time points. Similar results were reported in the present investigation when comparing the NLR ratio with different anesthetic procedures; the rise in NLR at 24 h after surgery in group GA when compared to groups TIVA and CSE/central neuraxial block has further supported the previous publication.^[13]

In this study, the NLR increases in group 1, followed by groups 2 and 3, respectively, similar to previous study.^[11] In a different retrospective study on finding a correlation between NLR and anesthetic procedures in patients receiving Caesarean section and authors found that postoperative NLR was significantly lower in these individuals after spinal anesthesia compared to general anesthesia.^[9] The above studies support our findings that more increase in NLR was seen with GA rather than TIVA, followed by neuraxial blockade. Overproduction of inflammatory mediators also occurs as a result of cellular immunity suppression, which is a significant inflammatory host response to surgical stress.^[14] Systemic leukocytic change, including leukocytosis, neutrophilia, and lymphopenia, may develop in response to surgery due to different hormones, cytokines, and acute phase reactants, lymphocyte death or neutrophil apoptosis suppression.^[15]

From the various studies, it can be concluded that those group of patients undergoing GA with propofol provides favorable effects on the immune system than sevoflurane; thus, it helps us to explain that the patient on TIVA will have a decreased immune response and thus the postoperative complication might be less. Our present study reflects that the increase in NLR was lesser in TIVA group as compared to general anesthesia group. Moreover, from the various studies discussed there was evidence that any increase in NLR ratio in cardiovascular patients, carcinoma patients, and chronic renal failure patients leads to an increase in morbidity and mortality, so it can be postulated that general anesthesia which shows an increase in NLR can be modified for such patients undergoing surgery and in that regard a detailed clinical investigation and history are very much important in order to have a better outcome of the patients and help us immensely in our patient management such that they will have a minimum level of stress.

It has been reported that NLR is considered as the simplest and inexpensive test to predict the immune status and to prognosticate the morbidity and mortality in patients with different comorbidities. Though various aspects of complications due to different anesthetic techniques have come to light, still it has been difficult to identify the effects of different anesthetic techniques on the inflammatory markers to see the outcome in postoperative patients. Postoperatively delayed immune response might occur either due to surgery or due to the different anesthetic techniques. The NLR as it is simple, easy to procure, and inexpensive can be a better option to look for inflammatory response for better outcome of the patients, so this present study was an attempt to answer some of these queries to a large extent for the better outcome of the patient.

In the present study, when we studied the effects of different anesthetic techniques on MLR, we found a significant difference at 6 and 24h after surgery in general anesthesia group, which could be attributed to duration of time. MLR is a good prognosticating factor for septicemia, and for delayed immune response after surgery. No previous studies have reported the effects of different anesthetic techniques with MLR. Studies that have reported MLR of prognosticate value where it is seen that increase in MLR was associated with outcome of several diseases, such as cancer, coronary heart diseases, hepatitis, human immunodeficiency virus, and tuberculosis.^[16,17] For patients with advanced gastric cancer and hepatocellular carcinoma undergoing neoadjuvant therapy, the MLR is considered as an independent prognostic factor; one such a study was conducted on 133 ovarian cancer patients and 43 controls were retrospectively evaluated, and they gave the conclusion that increase MLR is a strong risk factor for advance ovarian cancer patients, and it also reflects the immune status of the patient.^[18]

Nausea was seen to be present in 98 patients (32.6%) and no significant difference was seen (P-value > 0.05). The number of patients having nausea in group 1—38 (38%), group 2—25 (25%), and group 3—35 (35%). A study done to see the effects of TIVA with propofol reduces postoperative nausea and vomiting in patients undergoing Robotic—Assisted Laparoscopic Radical Prostatectomy. Their results reported that in TIVA after 1–6 h after surgery, the incidence of nausea was seen to be 16.1% compared to desflurane and remifentanil group (54.8%).

The study posed some limitations. During the surgery, the difference in the degree of pain control might have contributed to the difference of leukocytic alteration which was not done in this present study. Second, the follow-up of anesthetic techniques could have been more than 24 h in order to see the delayed immune response and settlement of inflammatory response. Third, due to the large sample size and cost constraints, comparison with IL6 and D dimer was not done. We identified the constraint that the anesthesiologist could not be blinded to group allocation because this was a study comparing three different anesthesia strategies; however, a biochemistry expert who analyzed markers was unaware of the group allocation.

Conclusion

This study has demonstrated that the type of anesthesia plays a role in postoperative NLR changes, and in this present study, it was seen that in patients undergoing major non-cardiac surgery, under general anesthesia had an increase in NLR at different time points (starting from end of surgery till 24 h post-surgery) than TIVA followed by neuraxial blockade. The mean comparison of NLR at 24 h after surgery was found to be significant when comparison was made between GA and TIVA, GA and CSE; however, the difference was found to be insignificant when comparison was made between group TIVA and CSE group. Highest rise in the mean NLR 24 h after surgery was found in patients who underwent surgeries under GA than TIVA followed by neuraxial blockade. In accordance with the present study, it can be concluded that anesthesia techniques can be modified for patients undergoing major non-cardiac surgeries in order to deduce the inflammatory response and complications and to have a better outcome of the patient. NLR can be considered a better test option to test inflammatory response in a developing country, due to its cost-effectiveness.

Acknowledgement

Nil.

Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.