Gravity-drain versus closed-suction subfascial drainage following lumbar decompression and fusion

Abstract

Background

Subfascial drainage is commonly used following lumbar laminectomy and fusion to reduce postoperative hematoma and wound-related complications. While closed-suction drainage is traditionally employed, concerns exist regarding increased blood loss and prolonged drain output. Gravity off suction drainage represents an alternative approach; however, data comparing its safety and efficacy to closed-suction systems in lumbar spine surgery are limited. The purpose of this study was to evaluate the efficacy and safety of gravity off suction subfascial drainage in lumbar laminectomy and fusion cases.

Methods

A retrospective review was performed of lumbar procedures by four surgeons at a single institution from March 2018 through December 2020 in a tertiary care, community teaching hospital. Elective posterior-only lumbar laminectomy and fusion procedures were included. Cervical and thoracic cases, cases undergoing osteotomy, and minimally invasive lumbar cases were excluded from the study. A total of 196 patients were included in the study (100 in the gravity-drain group and 96 in the closed-suction group).

Results

Significantly fewer patients in the gravity-drain group (38%) needed a blood transfusion vs. the closed-suction group (63%, P=0.001), and drain output was significantly lower in the gravity-drain group vs. the closed-suction group (350 vs. 499 mL, respectively, P=0.01). There were no occurrences of postoperative symptomatic spinal epidural hematoma (SEH) in the gravity-drain group, and one patient in the closed-suction group developed a compressive hematoma requiring evacuation.

Conclusions

This study demonstrated that, after elective lumbar laminectomy and fusion surgery, gravity drainage resulted in lower transfusion rates and drain output when compared to closed-suction drainage. These findings suggest that use of gravity drainage decreases the risk of postoperative blood loss and blood transfusion requirements without increasing the risk of symptomatic epidural hematoma after posterior lumbar fusion.

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Key findings

• When compared to closed-suction cases, postoperative drains placed to gravity-drainage were associated with lower rates of postoperative blood transfusions in patients who underwent elective lumbar laminectomy and fusion surgery. There were no cases of postoperative symptomatic epidural hematoma in the gravity-drainage group.

What is known and what is new?

• There is no consensus regarding the routine use of prophylactic drain placement to mitigate the risk of symptomatic epidural hematoma after lumbar laminectomy and fusion surgery, although the use of subfascial drains remains widespread. Closed-suction drainage has been associated with increased risk of postoperative anemia requiring blood transfusion, which can in turn result in increased risk of infection and healthcare expenditure. Foregoing the drain altogether has been associated with dressing saturation and need for postoperative wound aspiration.

• This study suggests that gravity drainage is safe and result in less need for postoperative blood transfusion after lumbar laminectomy and fusion surgery, thus mitigating negative potential risks of receiving donor blood, without increased risk of symptomatic epidural hematoma requiring postoperative bedside wound aspiration.

What is the implication, and what should change now?

• The current study implies that surgeons can safely place drains to gravity drainage and reduce the need for postoperative blood transfusion after lumbar laminectomy and fusion. Future studies may consider a more detailed stratification of groups to better investigate cases that might impact intraoperative and postoperative blood loss. Examples would include number of levels treated, revision surgery, and patient factors such as body mass index and history of hypertension. Any differences in healthcare expenditure between the two groups would also be considered.

Introduction

Compressive spinal epidural hematoma (SEH) is a rare but serious complication after spinal surgery that may yield catastrophic neurologic consequences. Incidence rates range from 0.1–1.2% for symptomatic SEH and up to 58% for asymptomatic SEH in patients after lumbar decompression surgery. In addition to meticulous homeostasis at closing, a traditional method for reducing the risk of symptomatic SEH is the placement of a subfascial wound closed-suction drain to decompress the operative bed postoperatively (1-4). Although a 2016 systematic review concluded that evidence is insufficient to support routine prophylactic use of closed-suction drains, a survey study reported that 69% of surgeons continue to utilize closed-suction drains as a mainstay of postoperative management for lumbar fusion cases (5,6). Utilization of closed-suction drains, however, has been associated with increased postoperative blood loss and a greater chance of requiring blood transfusion when compared to no drain or drain off-suction systems (7,8).

Extradural, subfascial gravity drainage systems in the lumbar spine are most often utilized in the context of a cerebrospinal fluid (CSF) leak. Once the dural tear has been repaired, maintaining the drain off closed-suction theoretically allows the subfascial pressure to dictate the amount of drainage, without extracting additional CSF from the subdural space (9) In the context of mitigating the risks of a symptomatic SEH, Lu et al. compared gravity drainage vs. closed-suction in a cohort of patients undergoing cervical laminoplasty and found lower hemoglobin levels and increased transfusion rates in the closed-suction group (10).

Gravity drains are a type of surgical drainage system that rely on gravity and capillary action to remove fluid from an operative site without applying suction force. Gravity drains consist of a standard sterile postoperative drain joined to a sterile collection bag via sterile tubing, secured using standard connectors, and have typically been used in clinical situations where aggressive drainage with a suction may delay healing or promote fistula formation (11).

Our study examined whether differences in blood transfusion rates exist between gravity-drainage systems and closed-suction drains following lumbar laminectomy and fusion procedures. Additional outcomes evaluated included occurrence of symptomatic epidural hematoma, drain output, and drain indwelling time in the two groups. We hypothesized that the gravity-drainage group would have lower transfusion rates and drain output compared with the closed-suction group. We present this article in accordance with the STROBE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-24-43/rc).

Methods

Study population

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the MedStar Health Research Institute (MHRI) Institutional Review Board (No. STUDY00003452). Due to the retrospective nature of the study and use of de-identified data, the requirement for informed consent was waived by the institutional review board. A retrospective review was performed to identify a total of 200 consecutive cases, 100 for each of the two study arms. We queried our electronic medical records system to identify elective lumbar laminectomy and fusion procedures from March 2018 through December 2020, at MedStar Union Memorial Hospital. For all cases a subfascial Jackson-Pratt wound drainage reservoir was placed at the end of the procedure. The drain was placed either to gravity-drainage alone (off-suction) or on closed-suction (on-suction), per the surgeon’s preference. Cervical and thoracic cases, osteotomy cases, minimally invasive lumbar procedures, and cases complicated by dural tear/CSF leak were excluded.

Procedures were limited to elective posterior-approach only lumbar laminectomy and fusion procedures completed by 4 fellowship-trained orthopaedic spine surgeons. Four patients were excluded because of incorrect Current Procedural Terminology (CPT) coding or errors with drain placement or function identified during chart review, leaving 196 patients included in the study. Of the included 196 patients, 100 were in the gravity-drain group and 96 were in the closed-suction group. The gravity-drain group had significantly more women (58%) compared with the closed-suction group (44%; P=0.04). There was no significant difference in median age between groups (68 vs. 65 years; P=0.18).

Data collection

Data were obtained from the electronic medical record system and included patient age and sex, date of service, date of discharge, Hemovac drain placed on gravity-drain vs. closed-suction, drain output, indwelling drain duration, need for postoperative wound aspiration or need to return to the operating room for hematoma evacuation, and need for post-operative blood transfusion.

Statistical analysis

Descriptive statistics were used for demographic and clinical characteristics of patients. Chi-squared test was used to compare categorical variables between the groups, and since our continuous variables were not normally distributed per the Shapiro-Wilk test, Wilcoxon rank-sum test was used to compare distributions of continuous variables between groups, and these are reported as medians with interquartile ranges (IQRs). Multivariable linear regression analyses were done to compare the number of days the drain was retained. A P value of 0.05 was used for determining statistical significance. All statistical analysis was performed with Stata version 17 (StataCorp LLC).

Results

Patients in the gravity-drain group had significantly lower rates for transfusion compared with the closed-suction group [38% (38/100) vs. 63% (60/96); P=0.001]. Additionally, the gravity-drain group had a significantly lower postoperative drain output compared with the closed-suction group [350 mL (IQR, 210–620 mL) vs. 499 mL (IQR, 288–783 mL); P=0.01]. No patients in the gravity-drain cohort developed a symptomatic SEH in the postoperative period. One patient from the closed-suction cohort developed a symptomatic SEH and required a return to the operating room for evacuation. Drain indwelling time and length of hospital stay were similar between groups [median 2 days (IQR, 2–3 days) vs. 2 days (IQR 2–3 days), P=0.55; and median 3 days (IQR, 2–4 days) vs. 3 days (IQR 2–4 days), P=0.37, respectively]. There were no cases requiring bedside wound aspiration for saturated dressings in either group (Table 1).

Table 1. Comparison of clinical outcomes between gravity-drain and closed-suction groups.

Variable	Gravity-drain group	Closed-suction group	P value
Transfusion rates (%)	38	63	0.001
Median postoperative drain output (mL)	350	499	0.01
Number of symptomatic spinal epidural hematomas	0	1	–
Median drain indwelling time (days)	2	2	0.55
Median length of hospital stay (days)	3	3	0.37
Number of bedside wound aspirations	0	0

Discussion

In this study, gravity drainage was associated with a significantly lower blood transfusion rate and less postoperative drain output compared to closed-suction drainage. The blood transfusion decisions were based on clinical judgement and institutional thresholds, and may be impacted by factors such as perioperative anticoagulant use and postoperative anemia, which were not systematically accounted for in this study. The occurrence of symptomatic SEH was low in both groups, with no symptomatic SEH in the gravity-drain group. These findings suggest that gravity drainage systems represent a safe and effective alternative to closed-suction drainage after posterior lumbar fusion.

Strengths of this investigation include this being, to the best of our knowledge, the first study of its kind investigating the impact of gravity drainage systems following uncomplicated lumbar surgery. Furthermore, the study was conducted at a single tertiary care hospital with fixed post-op protocols and the same four fellowship-trained spine surgeons throughout the data gathering period. Accurate electronic medical records were available for all but 4 of the 200 patients enrolled. Limitations include the lack of data on preoperative hemoglobin level, a factor that might affect postoperative transfusion rates. However, because all cases were elective, patients underwent appropriate preoperative medical clearance and patients with preoperative anemia would not have been cleared for elective spinal fusion cases. Additionally, we did not stratify patients based on intraoperative blood loss, number of levels fused, or revision surgery. The surgeries were done at one tertiary care center and may not extrapolate to other settings.

Symptomatic postoperative anemia after spinal surgery is typically addressed with blood transfusion and fluid resuscitation (5,7). In our study, when examining drain fluid losses postoperatively, we found that patients who had a drain placed to gravity drainage had significantly lower output and subsequent lower need for blood transfusion than in the closed-suction group. We speculate that gravity drains may allow for gentle pressure release within the wound allowing for necessary drainage, and the lack of negative pressure may also help to ensure sufficient coagulation and hemostasis postoperatively. Our postoperative drain output results are comparable to previous findings demonstrating lower drain output from gravity drainage compared to closed-suction drainage after cervical laminoplasty and lumbar fusion (9,10). Although blood transfusion may be necessary for cardiopulmonary and volume resuscitation, it entails risk of potential adverse effects. Several studies have shown that allogeneic red blood cell transfusion in spine surgery may be a risk factor for postoperative infection and increased healthcare costs (12-16). Although infection rates and increased healthcare expenditure were not a focus of this current investigation, we believe that a reduction in blood transfusion rates may help mitigate these undesired outcomes.

There were no occurrences of postoperative symptomatic SEH in the gravity-drainage group. These data suggest that placing drains to gravity-drainage does not increase risk of symptomatic SEH. Placement of postoperative, subfascial closed-suction drain is typically used as a way of mitigating potential risk of developing compressive SEH that may require a return trip to the operating room for evacuation. However, closed-suction drains have also been reported to be associated with postoperative anemia, higher rate of blood transfusion, and longer hospital stay (7,17-21). Absence of a postoperative drain has also been associated with adverse effects. In a study investigating no drain vs. closed-suction drain in patients undergoing multilevel lumbar fusion, Gubin et al. found that not utilizing a drain postoperatively resulted in increased wound soakage and the need for postoperative wound aspirations (18). The theoretical advantage we postulated with a gravity-drainage system was to provide the advantages of a closed-suction apparatus without the disadvantages of foregoing a drain altogether.

Future studies are needed to further elucidate the safety and efficacy of gravity-drain systems compared to closed-suction drainage. Specifically, patients should be stratified to better investigate factors that would impact intraoperative and postoperative blood loss. Examples would include number of levels treated, intraoperative blood loss, utilization of intraoperative cell saver for autologous blood transfusion, revision surgery, use of perioperative anticoagulants, postoperative anemia, and patient factors such as body mass index and history of hypertension. Future investigations should also include the healthcare expenditure implications of gravity-drainage vs. closed-suction systems. These would include the costs associated with blood transfusion, any resultant delay in hospital discharge, and differences in postoperative infection rates between the groups.

Conclusions

This study demonstrated that, after elective lumbar laminectomy and fusion surgery, gravity drainage resulted in lower transfusion rates and drain output when compared to closed-suction drainage. These findings suggest that use of gravity drainage may be associated with reduced risk of postoperative blood loss and blood transfusion requirements, without an increase in symptomatic epidural hematoma after posterior lumbar fusion.

Supplementary

The article’s supplementary files as

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the MedStar Health Research Institute (MHRI) Institutional Review Board (No. STUDY00003452). Due to the retrospective nature of the study and use of de-identified data, informed consent was waived by the institutional review board.

Data Sharing Statement

Available at https://jss.amegroups.com/article/view/10.21037/jss-24-43/dss

jss-12-04-46-dss.pdf ^{(69.8KB, pdf)}

DOI: 10.21037/jss-24-43