Which Criterion for Wound Drain Removal is Better Following Posterior 1-Level or 2-Level Lumbar Fusion With Instrumentation: Time Driven or Output Driven?

Abstract

Study Design:

Case-control study.

Objectives:

To compare the outcomes of 2 different criteria (time driven and output driven) for wound drain removal and identify which one is better.

Methods:

743 patients who underwent posterior lumbar fusion with instrumentation involving 1 or 2 motion segments were enrolled in this study. Based on the different criteria for drain removal, the patients were divided into 2 groups. The drains were discontinued by time driven (postoperative day 2) in group I and output driven (<50 ml per day) in group II. Demographic characteristics, perioperative parameters and clinical outcomes were compared between the 2 groups.

Results:

The demographic characteristics in both groups were comparable. The postoperative drain output, total blood loss, postoperative timing of ambulation, and postoperative duration of hospital stay in group I were lower than those in group II (P < 0.001). There was a higher proportion of patients requiring postoperative blood transfusion in group II, but not to a level of statistical significance (P = 0.054). There was no statistical significant difference in the incidence of surgical site infection (SSI) or symptomatic spinal epidural hematoma (SEH) between the 2 groups (P > 0.05).

Conclusions:

This study reveals that there are more benefits of wound drain removal by time driven than that by output driven for patients undergoing posterior 1-level or 2-level lumbar fusion with instrumentation, including less postoperative drain output, less total blood loss, earlier postoperative timing of ambulation and less postoperative duration of hospital stay without increasing the incidence of postoperative SSI or symptomatic SEH.

Keywords

time driven output driven wound drain removal surgical site infection symptomatic spinal epidural hematoma

Introduction

Closed-suction wound drains have been frequently used following posterior spinal fusion with instrumentation.^1,2 In theory, wound drains can prevent postoperative spinal epidural hematoma (SEH), thereby reducing the risks of postoperative neurological injury due to spinal cord compression, which is one of the most serious complications after spinal surgery.³ Additionally, postoperative SEH prevention may decrease the risks of surgical site infection (SSI) by removing the medium for bacterial growth.⁴ Although some studies have reported that wound drains were not beneficial for preventing postoperative SEH or SSI after spinal surgery, 88% of surgeons will use drains for posterior lumbar fusion with instrumentation from a survey among German spine surgeons regarding their use of drains.^5-7

However, the criteria in discontinuing drain use in spinal surgery are heterogeneous and controversial.^7,8 Urquhart et al. reported that all drains were discontinued by postoperative day 2 in patients undergoing posterior spinal surgery from a randomized controlled trial.⁹ In the study of von Eckardstein et al, 98.5% of surgeons chose to remove wound drains by postoperative day 4 after posterior lumbar interbody fusion.⁷ Ren et al. described that drain output of less than 50 ml per day was considered as the standard for drain removal after posterior lumbar instrumented spinal fusions.¹⁰ In a case-control study of 1587 patients who underwent spinal fusion procedures, drain removal mainly depended on the amount of drain output (typically <100 ml per day).¹¹

Although a number of surgeons have reported their criteria to discontinue drain use according to either drain output or a predetermined time for posterior spinal fusion with instrumentation, so far, few studies have directly compared the 2 criteria and identified which one is the optimal choice for wound drain removal. In the present study, wound drains were applied for all the patients undergoing posterior 1-level or 2-level lumbar fusion with instrumentation, and they were discontinued by time driven (postoperative day 2) or output driven (<50 ml per day). The aim of this study was to compare the outcomes of 2 different criteria for wound drain removal and identify which one is better.

Materials and Methods

Study Design and Patient Population

This study was based on a retrospective analysis of a prospective database. The study was performed in compliance with ethical standards and was approved by the institutional review board (2019ZDSYLL101-P01). All patients in this study obtained informed consent before surgical procedures. From January 2017 to January 2019, 743 patients with lumbar degenerative diseases who underwent posterior lumbar fusion with instrumentation involving 1 or 2 motion segments by 7 spine specialists of the same level of qualification and experience in a single center were enrolled in this study. Patients with intraoperative dural tear, more than 2-level fusion surgery, previous lumbar surgery, systemic autoimmune disease or spondylodiscitis, or incomplete medical record information were excluded. All patients were followed up for more than 1 year postoperatively. The wound drains were placed prior to incision closure in all surgeries in this study.

Based on the different criteria for drain removal, the patients were divided into 2 groups (group I and group II). The drains were discontinued on the predetermined postoperative day 2 for patients in group I by 3 of 7 spine specialists and according to the amount of drain output with less than 50 ml per day for patients in group II by the other 4 specialists.

Treatment Protocol

All patients were placed in a prone position and under general anesthesia. Surgical procedures were similar in 2 groups, including conventional midline approaches with unilateral or bilateral decompression, posterior lumbar interbody fusion or transforaminal lumbar interbody fusion with pedicle screws and rod instrumentation. After ensuring adequate decompression of nerve roots and spinal cord and meticulous hemostasis, 1 or 2 silicone/closed-suction drains were inserted into the subfascial space before incision closure. One drain was used when the spinous process was removed, and 2 drains were used when the spinous process was retained, 1 on each side. Then, muscle, fascia, and skin were closed layer by layer. In group I patients, the drains were removed by postoperative day 2. In group II patients, the drains were discontinued when the daily amount of drain output was less than 50 ml. All patients were encouraged to ambulate as early as possible after drain removal.

Regarding to blood transfusion indications, the conditions of all patients were monitored intraoperatively by an anesthesiologist who decided whether to transfuse. After surgery, the blood routine were regularly reviewed for all patients. Blood transfusion was performed if postoperative hemoglobin level was less than 8 g/dL or for the patient with hemoglobin level between 8 and 10 g/dL who had the following symptoms, including sustained tachycardia with a heart rate of more than 100 beats per minute for at least 4 hours, chest pain, dyspnea, malaise (inability to comply with physical therapy exercises) and hypotension with a drop in systolic blood pressure of more than 20 mmHg under appropriate clinical conditions.^1,12

All patients in both groups received the same perioperative antibiotic protocol, including administration of prophylactic antibiotics with first generation cephalosporin 1 hour before surgical incision and 48 h postoperatively. If the operation lasted more than 3 hours, a second dose of antibiotics was given intraoperatively at the 3-hour mark. Vancomycin was used as an alternative when the patient was allergic to cephalosporin.

Data Collection

Demographic characteristics were recorded including age, gender, body mass index (BMI), medical history (smoking, hypertension, diabetes mellitus, rheumatoid arthritis, coronary heart disease, chronic obstructive pulmonary disease).

Perioperative parameters were collected including surgical duration, number of fusion levels, intraoperative blood loss, postoperative drain output, total blood loss, number of intraoperative autologous or allogeneic blood transfusion, number of postoperative blood transfusion, postoperative timing of ambulation, postoperative duration of hospital stay and postoperative complications (SSI and symptomatic SEH). The definition of SSI was identified according to the guidelines from the United States Centers for Disease Control and Prevention, which was divided into superficial, deep, and organ or space infection.¹³

All patients were followed up regularly. Clinical efficacy was evaluated using the visual analogue scale (VAS) for back and leg pain and the Oswestry disability index (ODI) preoperatively, at 3 and 12 months postoperatively.¹⁴

Statistical Analysis

All data was analyzed using SPSS Statistics software (version 22.0, SPSS Inc, Chicago, IL, USA). The comparative analyses between 2 groups were made using the Mann-Whitney U test for continuous nonparametric variables or the Student t test for continuous parametric variables. Categorical variables between 2 groups were compared using Chi-square test or Fisher’s exact test. The differences of VAS and ODI of each group before and after surgery were analysed using Dunnett-t test. The P values of <0.05 was considered to be statistically significant.

Results

The demographic characteristics of patients in both groups are presented in Table 1. There were no significant differences in age (P = 0.172), gender (P = 0.962), BMI (P = 0.394), medical history (P > 0.05) between the 2 groups.

Table 1.

Comparison of Demographic Characteristics of Patients Between Group I and Group II.

Parameter	Group I (n = 315)	Group II (n = 428)	P
Age (years)	58.9 ± 10.8	57.7 ± 11.2	0.172
Gender (male/female), n	154/161	210/218	0.962
BMI (kg/m²)	24.3 ± 3.1	24.5 ± 3.2	0.394
Medical history (n, %)
Smoking	68 (21.6)	96 (22.4)	0.784
Hypertension	125 (39.7)	173 (40.4)	0.839
DM	26 (8.3)	35 (8.2)	0.970
RA	9 (2.9)	11 (2.6)	0.811
CHD	20 (6.3)	26 (6.1)	0.878
COPD	7 (2.2)	8 (1.9)	0.735

BMI body mass index, DM diabetes mellitus, RA rheumatoid arthritis, CHD coronary heart disease, COPD chronic obstructive pulmonary disease.

Table 2 shows the perioperative characteristics of patients between group I and group II. There were no statistical significant differences in the surgical duration (P = 0.143), number of fusion levels (P = 0.438), intraoperative blood loss (P = 0.908), the number of patients requiring intraoperative blood transfusion (P = 0.747), and the incidence of SSI (P = 0.213) or symptomatic SEH (P = 0.391) between the 2 groups. One patient with a drainage tube removed on postoperative day 3 when the drain output was less than 50 ml developed a symptomatic SEH after wound drain removal in group II (Figure 1). The postoperative drain output (P < 0.001), total blood loss (P < 0.001), postoperative timing of ambulation (P < 0.001), and postoperative duration of hospital stay (P < 0.001) in group I were significantly lower than those in group II. There was a higher proportion of patients requiring postoperative blood transfusion in group II, but not to a level of statistical significance (P = 0.054). The mean value of drain output in group I on postoperative day 0 and 1 were 275.8 ± 130.8 and 115.7 ± 62.9 ml while the count in group II were 287.3 ± 138.2 and 121.4 ± 71.6 ml, respectively. The drain output on postoperative day 0 and 1 was comparable between the 2 groups (Figure 2). The drains of all patients in group I were removed by postoperative day 2. In group II patients, the rate of drainage tube removal on postoperative day 2, 3, 4, 5 and 6 was 8.6%, 52.8%, 30.4%, 7.0% and 1.2%, respectively (Figure 3). The mean drainage duration in group II was 3.4 days.

Figure 1.

The patient was a 57-year-old female who underwent posterior lumbar fusion with instrumentation for degenerative spondylolisthesis. Progressive leg weakness and perianal numbness occurred on postoperative day 3 after wound drain removal in group II. MRI examination was immediately assessed, and revealed a symptomatic spinal epidural hematoma at L3-L5 level (A, B, C). Then the patient received reoperation for hematoma evacuation immediately. The spinal epidural hematoma accumulation was found around initial surgical area (D, E) and completely removed (F).

Figure 2.

The mean value of drain output in group I on postoperative day 0 and 1 were 275.8 ± 130.8 and 115.7 ± 62.9 ml while the count in group II were 287.3 ± 138.2 and 121.4 ± 71.6 ml, respectively. The drain output on postoperative day 0 and 1 was comparable between the 2 groups (P = 0.252, P = 0.260, respectively).

Figure 3.

The drains of all patients in group I were removed by postoperative day 2. In group II patients, the rate of drainage tube removal on postoperative day 2, 3, 4, 5 and 6 was 8.6%, 52.8%, 30.4%, 7.0% and 1.2%, respectively.

Table 2.

Comparison of Perioperative Characteristics of Patients Between Group I and Group II.

Parameter	Group I (n = 315)	Group II (n = 428)	P
Surgical duration (min)	148.7 ± 35.4	152.6 ± 36.2	0.143
Number of fusion levels (n, %)			0.438
One	178 (56.5)	254 (59.3)
Two	137 (43.5)	174 (40.7)
Intraoperative blood loss (ml)	286.3 ± 192.1	287.9 ± 183.8	0.908
Postoperative drain output (ml)	391.7 ± 174.7	576.4 ± 228.7	<0.001
Total blood loss (ml)	678.3 ± 256.3	864.3 ± 284.0	<0.001
Number of intraoperative blood transfusion (n, %)	88 (27.9)	115 (26.8)	0.747
Autologous blood (n, %)	83 (26.3)	108 (25.2)	0.731
Allogeneic blood (n, %)	5 (1.6)	7 (1.6)	0.959
Number of postoperative blood transfusion (n, %)	9 (2.9)	25 (5.8)	0.054
Postoperative timing of ambulation (days)	2.6 ± 0.6	3.8 ± 0.7	<0.001
Postoperative duration of hospital stay, mean (days)	7.6 ± 2.8	8.5 ± 3.4	<0.001
Complications (n, %)
SSI (n, %)	4 (1.3)	11 (2.6)	0.213
Superficial (n, %)	3 (1.0)	7 (1.6)	0.425
Deep (n, %)	1 (0.3)	3 (0.7)	0.480
Organ or space infection (n, %)	0 (0)	1 (0.2)	0.391
Symptomatic SEH (n, %)	0 (0)	1 (0.2)	0.391

SSI Surgical site infection, SEH spinal epidural hematoma.

Table 3 illustrates the clinical outcomes of patients before and after surgery in both groups. The ODI and VAS scores for back and leg pain improved from the preoperative assessment to postoperative 3 or 12 months in each group (P < 0.001). There were no statistical differences in the ODI and VAS scores for back and leg pain at the same time point between the 2 groups (P > 0.05).

Table 3.

Comparison of Clinical Outcomes of Patients Between Group I and Group II.

Parameter	Group I (n = 315)	Group II (n = 428)	P
VAS for back
Pre-op	7.1 ± 0.6	7.0 ± 0.7	0.153
Post-op 3 months	3.4 ± 0.5	3.3 ± 0.4	0.253
Post-op 12 months	2.3 ± 0.2	2.4 ± 0.3	0.296
VAS for leg
Pre-op	7.3 ± 0.6	7.2 ± 0.7	0.414
Post-op 3 months	2.9 ± 0.4	2.8 ± 0.5	0.380
Post-op 12 months	2.2 ± 0.2	2.1 ± 0.2	0.158
ODI
Pre-op	49.2 ± 6.2	48.3 ± 6.6	0.086
Post-op 3 months	25.8 ± 4.7	26.3 ± 4.8	0.157
Post-op 12 months	16.9 ± 3.5	17.4 ± 3.8	0.116

VAS visual analogue scale, ODI Oswestry disability index.

Discussion

Drains are widely used after spine surgery, though its benefits remain controversial.^5,15 Blank et al. found that the drainage for spinal surgery reduced wound complications and the frequency of needed dressing changes without increasing blood loss and the need for transfusion.¹⁶ Sen et al. reported that use of drains after lumbar spine surgery can result in less epidural fibrosis radiologically and achieve better clinical outcomes.¹⁷ However, The criteria for removing wound drains following spine surgery are inconsistent. Some surgeons discontinued drain use according to drain output, ranging from less than 30 ml to 100 ml per day.^2,6,11,18,19 Other surgeons removed drains by a predetermined time with the boundary from 12 hours to 48 hours postoperatively.^3,9,17 To the best of our knowledge, there are no published reports about the optimal choice for wound drain removal in 2 reference standards following posterior 1-level or 2-level lumbar fusion with instrumentation. Therefore, we carried out this study.

Based on our results, the mean drainage duration in group II (3.4 days) is longer than that in group I (2 days), which resulted in more postoperative drain output and total blood loss in group II. It further led to more patients requiring postoperative blood transfusion in group II, increasing potential risk of complications associated with transfusion and the cost of hospitalization for patients.

In the present study, postoperative timing of ambulation of patients in group I was earlier than that in group II. Patients in group I might feel more comfortable because of earlier removal of drainage tube and ambulation. Besides, it is beneficial for patients to carry out early rehabilitation function exercise, reducing thrombosis, bedsore and other bedridden complications. We believed that wound drain removal by postoperative day 2 would provide patients with a faster recovery, a more comfortable postoperative period and a higher degree of satisfaction.²⁰

SSI is a common and potentially devastating complication following spinal fusion procedures, and it is associated with increased morbidity, prolonged hospitalization and poor outcomes.^21,22 A case-control study performed by Rao et al. revealed that prolonged duration of drains was an independent risk factor for postoperative SSI in patients undergoing spinal fusion surgery with instrumentation for degenerative spinal diseases.¹¹ Liu et al. also reported that prolonged drainage duration was a risk factor for SSI after lumbar spinal surgery and suggested to remove the drain as early as possible to reduce the rate of SSI.²² In our study, the mean duration of drainage tube was 3.4 days in group II and 2 days in group I. The incidence rate of SSI in group II was 2.6%, higher than 1.3% in group I, although there was no statistical difference in the infection rate between the 2 groups. The reasons for prolonged drainage duration increasing the rate of SSI were that it may lead to local tissue inflammation and provide a direct path for bacteria by ascending the drain tube.²² Additionally, some surgeons have found that bacterial colonization of the drain tube increases as the drain stayed longer and SSI is frequently resulted from the same bacteria isolated from the drain.^11,23 Therefore, this study revealed that the method of wound drain removal by time driven (postoperative day 2) is more advantageous than that by the amount of output driven (<50 ml per day) in terms of reducing the infection rate.

Postoperative SEH is another hazardous complication after spinal fusion procedures. It can be divided into symptomatic and asymptomatic SHE.²⁴ Although the incidence rate of symptomatic SEH is less frequently, ranging from 0.1% to 0.7%, it can result in serious neurological consequences, including bowel and bladder dysfunction, lower limb weakness, intractable pain and saddle anesthesia.^1,25 Kao et al. reported that postoperative drain volume was a significant risk factor for symptomatic SEH after posterior lumbar decompression surgery with/without instrumentation.²⁵ According to our study, the total blood loss and postoperative drain output in group II were more than that in group I. However, there is no significant difference in the incidence rate of symptomatic SEH between the 2 groups. We suggest the following possible reasons: Several authors have reported that symptomatic SEH usually occurs within the first few hours after the initial surgery, but drainage tubes were retained for at least 2 days in all patients of both groups in our study.^3,25 In addition, the limited sample size in both groups may also be responsible for the incomparability of symptomatic hematoma formation between the 2 groups since symptomatic SEH is inherently rare in clinical practice.

We acknowledge there are some limitations in this study. First, the amount of blood loss in this study was measured on the basis of visible intraoperative bleeding and postoperative drainage. We did not calculate the hidden blood loss due to haematocrit drop, which may affect the accuracy of results on blood loss. We supposed that the hidden blood loss in both groups was identical. Second, this was a retrospective study in a single center. However, all the patients underwent surgeries by 7 spine specialists who have the same level of qualification and experience to reduce the surgeon-specific difference. Third, the drains were removed by postoperative day 2 in 8.6% of patients in group II when the amount of drain output was less than 50 ml per day, which may cause a confounder about the criteria of wound drain removal since the drains of all patients in group I were discontinued on the predetermined postoperative day 2. Nonetheless, in order to ensure the authenticity and reliability of the results, we did not exclude those patients who had their drains removed by postoperative day 2 in group II. Finally, because of limited surgical segments (1-level or 2-level), the present study’s outcomes may not be applied for patients undergoing posterior lumbar fusion with instrumentation involving more than 2 segments. Therefore, a prospective randomized controlled trial for extensive spine surgery should be performed to identify the standard protocols for drain removal.

Conclusion

This study reveals that there are more benefits of wound drain removal by time driven (postoperative day 2) than that by output driven (<50 ml per day) for patients undergoing posterior 1-level or 2-level lumbar fusion with instrumentation, including less postoperative drain output, less total blood loss, earlier postoperative timing of ambulation and less postoperative duration of hospital stay without increasing the incidence of postoperative SSI or symptomatic SEH.

Footnotes

Authors’ Note

The study was performed in compliance with ethical standards and was approved by Southeast University ZhongDa Hospital institutional review board (IRB 2019ZDSYLL101-P01).

Author Contribution

Hang Shi, Zhi-Hao Huang, and Yong Huang contributed equally to this study. Conception and design: Xiao-Tao Wu. Acquisition of data: Hang Shi, Zhi-Hao Huang, Yong Huang, Zan-Li Jiang, Yun-Tao Wang, Zhi-Yang Xie. Analysis and interpretation of data: Hang Shi, Zhi-Hao Huang, Yong Huang, Lei Zhu. Drafting the article: Hang Shi. Critically revising the article: Lei Zhu, Xiao-Tao Wu. All authors read and approved the final manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

ORCID iD

Hang Shi, MD

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