Abstract
Background Pneumatic tourniquets are widely used in hand surgery. Elevated pressures can be associated with complications, and thus, guidelines based on patient-specific tourniquet pressures have been recommended. The primary aim of this study was to determine whether lower tourniquet values based on systolic blood pressure (SBP) could be effectively applied in upper extremity surgery.
Methods A prospective case series of 107 consecutive patients undergoing upper extremity surgery with use of a pneumatic tourniquet was performed. Tourniquet pressure used was based on the patient's SBP. The tourniquet was inflated based on our predetermined guidelines: 60 mm Hg was added for SBP < 130 mm Hg, 80 mm Hg for SBP between 131 and 190 mm Hg, and 100 mm Hg for SBP > 191 mm Hg. The outcome measures included intraoperative tourniquet adjustment, surgeon-rated quality of bloodless operative field and complications.
Results The mean tourniquet pressure was 183 ± 26 mm Hg with a mean tourniquet time of 34 minutes (range: 2–120 minutes). There were no instances of intraoperative tourniquet adjustment. The surgeon-rated quality of bloodless operative field was excellent in all patients. No complications were associated with the use of a tourniquet.
Conclusion Tourniquet inflation pressure based on SBP is an effective method to provide a bloodless surgical field in upper extremity surgery at significantly lower inflation pressures than are the current standards.
Keywords: upper extremity surgery, hand surgery, tourniquet, systolic blood pressure, bloodless surgical field
Introduction
Sterling Bunnell described the creation of a bloodless field as an essential component of hand surgery to allow for proper visualization of delicate structures and to decrease the trauma associated with hemostasis. 1 2 Accordingly, pneumatic tourniquets are widely used in hand and upper extremity surgeries.
The earliest known use of a tourniquet dates back to 1674 when Etienne Morel, a French Army surgeon, described the use of a stick to twist the soldier's bandage until the injury stopped bleeding. 2 3 The design evolved and in 1873, Friedrich Esmarch described the use of a rubber bandage for exsanguination followed by application of a tourniquet made of rubber tubing to occlude blood flow. 4 Several decades later in 1904, Harvey Cushing noted several complications associated with the use of such elastic tourniquets, including vasomotor palsy and pain, and subsequently described an inflatable tourniquet with the use of a bicycle pump. 5
Tourniquet design has continued to evolve; however, complications associated with their use have persisted and include pain and nerve, muscle, and skin injuries and are attributed to elevated tourniquet pressure and duration of ischemia. 6 7 8 Advancements in tourniquet design have sought to enhance the safety profile and mitigate these complications while maintaining a bloodless field. 9 10 11 12 13 It is still a common practice to apply a fixed tourniquet pressure of 250 to 300 mm Hg for extremity surgery despite evidence from the literature, suggesting that the use of patient-specific minimal effective tourniquet inflation pressures may decrease tourniquet-related complications while still providing a bloodless surgical field. 14 15 Guidelines have been suggested based on systolic blood pressure (SBP), limb occlusion pressure (LOP), and arterial occlusion pressure (AOP). Whereas LOP and AOP methods require additional time preoperatively to determine appropriate tourniquet pressure, SBP-based guidelines are determined at the time of exsanguination.
The primary aim of this study was to determine whether SBP-based guidelines could be safely and effectively applied in upper extremity surgery. Our hypothesis was that a tourniquet pressure based on SBP would result in a lower mean tourniquet pressure and provide a bloodless field.
Materials and Methods
We conducted an institutional review board (IRB) approved prospective case series of 107 consecutive patients undergoing upper extremity surgery. Patients over the age of 18 years undergoing upper extremity surgery with the use of pneumatic tourniquet were enrolled. Patient demographics (age, gender, and body mass index [BMI]), surgical procedure, type of anesthesia (local, regional [brachial plexus block], and intravenous [IV] sedation), location of tourniquet (proximal forearm or high arm), size of tourniquet, SBP, tourniquet pressure, and tourniquet time were recorded. Extremity circumference was measured at the estimated center of the tourniquet location on the extremity. The use of proximal forearm versus high-arm tourniquet location was at the discretion of the surgeon and dependent on the procedure. They were placed at a point of maximum circumference. All tourniquets were 3-inch wide from the same manufacturer (Stryker, Kalamazoo, MI) and were used in conjunction with a protective sleeve matched to the specific tourniquet cuff. Tourniquet length was 18 inches for all patients. Additional tourniquet lengths were available; however, the 18-inch length allowed for cuff overlap in all instances to allow for effective tourniquet inflation.
The Association of Perioperative Registered Nurses (AORN) has established a safety margin based on the LOP which accounts for variables such as vessel wall compliance, limb circumference, and cuff design. 16 Their recommendations, which are widely used in studies assessing the utility of LOP, are to add 40 mm Hg for LOP less than 130 mm Hg, add 60 mm Hg for LOP between 131 and 190 mm Hg, add 80 mm Hg for LOP greater than 190 mm Hg. However, this technique is time consuming and cumbersome which we felt was a major barrier to its incorporation into clinical practice. Thus we elected to use the patient SBP plus a modified safety margin. The modified safety margin in this study is similar to that used in the AORN guidelines; however, there is an additional 20 mm Hg of margin due to the limited correlation between LOP and SBP. 13 The additional safety margin would account for the greater variability of SBP compared with LOP. Immediately prior to exsanguination with the Esmarch bandage, the patient's SBP was determined. The tourniquet cuff was then inflated accordingly based on our predetermined guidelines: 60 mm Hg was added to the pressure for SBP < 130 mm Hg, 80 mm Hg for SBP between 131 and 190 mm Hg, and 100 mm Hg for SBP > 191 mm Hg. For example, if patient SBP is 100 mm Hg, tourniquet pressure used was 160 mm Hg.
The primary outcome measure was the need for intraoperative tourniquet adjustment or reinflation due to poor visualization from a bloody surgical field. The secondary outcome measure was the quality of bloodless operative field. Following each surgical procedure, the surgeon rated the quality of bloodless operative field using a previously validated 4-point scale: 1 (excellent) = no blood in surgical field ( Fig. 1 ), 2 (good) = some blood in the surgical field but no interference with surgery, 3 (fair) = blood in the surgical field but no significant interference with surgery, and 4 (poor) = blood in the surgical field obscures the view throughout the procedure. 15 Lastly, patients were examined immediately postoperatively for evaluation of any surgery-related or tourniquet-related complications.
Fig. 1.
Clinical Images of an “Excellent” surgical field. ( A ) Ulnar nerve decompression at the elbow in a normotensive patient (SBP < 130 mm Hg). ( B ) Radial tunnel decompression in a hypertensive patient (SBP > 130 mm Hg). SBP, systolic blood pressure.
Statistics
Descriptive statistics were used to provide a quantitative summary of the data in the study. Specifically, the analysis performed included measures of central tendency and measures of variability.
Results
A total of 100 patients were included in the study. Two patients were excluded after enrollment due to a decision by the primary surgeon to not elevate the pneumatic tourniquet. In both instances, a finger tourniquet was used. Five patients were excluded due to incorrect initial cuff pressure per the guidelines.
The mean age was 50 years (range: 19–88 years), and 58% were female. The average BMI was 28 ± 7 kg/m 2 with a majority of patients between 18.5 and 30 kg/m 2 ( Table 1 ). The mean number of procedures per patient was 1.2 (range: 1–5) with the two most common procedure locations being the wrist (44%) and hand (41%). The majority of cases were elective soft tissue procedures. Anesthetic management included regional block and IV sedation (53%), local (31%), and a combination of local and IV sedation (16%; Table 2 ). There was nearly even distribution of tourniquet application to the proximal forearm (48%) and high arm (52%), with a mean circumference of 26.6 ± 3.8 and 31.4 ± 4.6 cm, respectively ( Table 3 ).
Table 1. Demographic characteristics.
| Demographics | Mean ± SD/ n (%) |
|---|---|
| Age (y) | 50 ± 16.9 |
| Gender | |
| Male | 42 (42) |
| Female | 58 (58) |
| BMI (kg/m 2 ) | |
| Mean | 28 + 7 |
| < 18.5 | 0 (0) |
| 18.5 to 25 | 37 (35.9) |
| 25 to 30 | 35 (34) |
| 30 to 35 | 11 (10.7) |
| 35 to 40 | 8 (7.8) |
| > 40 | 7 (6.8) |
Abbreviations: BMI, body mass index; SD, standard deviation.
Table 2. Procedure characteristics.
| Characteristics | Mean ± SD/ n |
|---|---|
| No. of procedures | |
| Mean | 1.2 ± 0.7 |
| One | 85 |
| Two | 9 |
| Three | 4 |
| Four | 1 |
| Five | 1 |
| Location | |
| Hand | 41 |
| Wrist | 44 |
| Elbow | 4 |
| Multiple | 11 |
| Type | |
| Soft tissue | 73 |
| Bony | 27 |
| Elective | 80 |
| Trauma | 20 |
| Type of anesthesia | |
| Local | 31 |
| Local + IV sedation | 16 |
| Regional block + IV sedation | 53 |
Abbreviations: IV, intravenous; SD, standard deviation.
Table 3. Extremity and tourniquet characteristics.
| Proximal forearm | Upper arm | |
|---|---|---|
| Location | 48 | 52 |
| Extremity circumference (cm) | 26.6 ± 3.8 | 31.4 ± 4.6 |
| Systolic blood pressure (mm Hg) | ||
| Mean | 118.5 ± 19.8 | |
| < 130 | 78% | |
| 130 to 190 | 22% | |
| > 190 | 0% | |
| Delta systolic blood pressure (mm Hg) | ||
| Mean | 25 (range: 7–48) | |
| + Delta | 11 (range: 0–34) | |
| − Delta | 14 (range: 0–33) | |
| Tourniquet pressure (mm Hg) | ||
| Mean | 183 ± 26.3 | |
| Minimum | 140 | |
| Maximum | 260 | |
| Tourniquet time (min) | ||
| Mean | 34.1 ± 31 | |
| Minimum | 2 | |
| Maximum | 120 | |
The mean tourniquet pressure used was 183 ± 26 mm Hg with a mean tourniquet time of 34 minutes (range: 2–120 minutes). There were no instances of tourniquet adjustment. The surgeon-rated quality of bloodless operative field was excellent in all patients. No complications associated with the use of a tourniquet were noted in the immediate postoperative period ( Table 4 ).
Table 4. Tourniquet performance.
| Tourniquet | Performance |
| Tourniquet adjustment | 0 |
| Quality of bloodless operative field | |
| 1 (excellent) | 100 |
| 2 (good) | 0 |
| 3 (fair) | 0 |
| 4 (poor) | 0 |
| Complications | 0 |
Note: 1 (excellent) = no blood in surgical field, 2 (good) = some blood in the surgical field but no interference with surgery, 3 (fair) = blood in the surgical field but no significant interference with surgery, and 4 (poor) = blood in the surgical field obscures the view throughout the procedure. 15
Discussion
This study has shown that SBP-based tourniquet pressure use can consistently provide a bloodless surgical field for elective hand surgery. The tourniquet pressures used in this study resulted in a mean tourniquet pressure (183 mm Hg) that is significantly lower than the current standard fixed pressure of 250 mm Hg. There were no instances of obscured surgical field requiring tourniquet adjustment or reinflation and no tourniquet-related complications. As such, we were unable to identify an association with demographic, extremity characteristic, or surgical factors. Of note, as many hand surgery procedures are performed with the patients awake and under local anesthesia, lower tourniquet pressures may be better tolerated by awake patients, although this study did not specifically investigate this aspect.
Complications associated with tourniquet use are considered rare, although there is a concern that the actual incidence is underreported. 6 7 8 The spectrum of complications includes skin, muscle, blood vessel, and nerve injury. Odinsson and Finsen revealed that the overall incidence of complications was one per 3,526 (0.028%) with the most common complication being nerve injury followed by skin blistering and necrosis. 6 Multiple studies have characterized tourniquet-related muscle and nerve injury clinically and histologically, being attributed to duration of compression. 17 18 19 20 21 22 23 24 25 These findings translate clinically to impaired muscle function with regard to force production, fatigue, and contraction time which can last weeks. 18 A histologic study of rat sciatic nerves with a tourniquet pressure of 300 mm Hg showed ultrastructural nerve damage, from the Schwann cell hypertrophy, axonal shrinkage, and myelin rupture in some instances. 19 21 Compared with muscle injury, nerve complications are less vulnerable to acute injury but can persist for a longer period of time. 24 There were no tourniquet-associated complications reported in this study.
Tourniquet design, width, and contour have been shown to occlude blood flow at lower inflation pressures. 9 10 11 12 13 Graham et al noted that the occlusion pressure of a limb was inversely proportional to the ratio of the tourniquet cuff width to limb circumference. 9 These studies showed that while a tourniquet width of 8 cm provided occlusion at intermediate tourniquet pressures, a width of 18 cm was able to provide arterial occlusion at near-systolic to sub-SBPs. However, in upper extremity surgery, the limited length of the limb segments generally precludes the use of 18-cm wide tourniquet cuffs. Additionally, advocates of contoured tourniquets attribute lower LOP to a better fit resulting in a more uniform pressure transmission. 12 13 26 In the present study, the most commonly used tourniquet cuff length (18 inches) and width (3 inches) at our institution were applied to all the patients to mitigate cuff width as a confounding variable.
Multiple recommendations have been published to guide tourniquet duration, pressure, and reperfusion interval. 16 26 27 28 29 These are based on the widely used 2-hour tourniquet time limit which is primarily derived from animal studies showing clinical changes and histologic changes including myelin dissolution and the Schwann cell hypertrophy. Recently, more focus has been attributed to the tourniquet pressure, specifically, utilization of the minimal effective tourniquet inflation pressure to provide a bloodless surgical field. Minimal effective tourniquet inflation pressure can be calculated based on LOP and AOP or estimated based on SBP. LOP is determined by gradually inflating the cuff until distal blood is interrupted. AOP is a calculation based on SBP and tissue padding coefficient. These are both effective at lowering tourniquet pressures; however, they require additional time and calculation which may translate to operating room inefficiency. 14 15 16 30 31 32 Our proposed method simplifies this process and provided a bloodless surgical field with a rating of “excellent” in all instances, similar to those studies using LOP and AOP. 13 15 Additionally, the mean tourniquet pressure of 183 mm Hg in our series was significantly lower than the fixed 250 to 300 mm Hg routinely applied.
Limitations
Limitations of this study include the lack of a comparison group. The current literature on patient-specific tourniquet pressures also includes the use of LOP and AOP; however, the reported results are in lower extremity procedures and difficult to compare. The consistency in which SBP-based tourniquet pressures relates to LOP/AOP with regard to effectiveness in providing a bloodless field and difference in tourniquet pressure is an area of future research. Another limitation of patient-specific tourniquet pressure guidelines is that they are somewhat arbitrary. The initial tourniquet pressure guidelines described by the AORN were based on LOP with a suggested safety margin. The guidelines for this study were based on SBP and, therefore, we decided to use a greater safety buffer due to the limited correlation between LOP and SBP and fluctuations of SBP during surgical procedures. The mean intraoperative change in SBP in our study was 25 mm Hg. The mean change in SBP above and below the starting SBP was 14 (range: 0–33) mm Hg and 11 (range: 0–34) mm Hg, respectively. The safety margin in each instance was greater than the intraoperative fluctuation in SBP. Further comparative studies are needed to further our understanding of the most appropriate tourniquet pressure that is both safe and efficacious.
Another limitation is the subjective nature of the grading scale used in this study to characterize the quality of bloodless operative field. Grading scales are inherently subjective as they rely on the observer's perception. The use of intra-operative photographs or multisurgeon assessments to determine interobserver reliability would have aided in assessing the subjectivity and strengthened the results. Additionally, the methodology of this study did not allow for blinding of the surgeon which could result in bias with regard to reporting the quality of bloodless operative field. Lastly, this study was not sufficiently powered to determine if this method of determining tourniquet pressure decreased the incidence of complications as compared with rates reported in the literature.
Conclusion
In conclusion, tourniquet inflation pressure based on SBP is an effective method to provide a bloodless surgical field in upper extremity surgery at a significantly lower inflation pressure than the current standard. Given the well-characterized association between tourniquet pressure and soft tissue injury, the reduction of tourniquet pressure using this method adds to the body of literature aiming to mitigate these complications. As wide-awake surgery becomes more popular, methods of decreasing tourniquet pressure will become increasingly important to improve patient comfort during procedures. This method provides a safe and simple guideline for personalizing tourniquet pressures for use in commonly performed upper extremity procedures. A randomized follow-up study comparing this method to a fixed tourniquet pressure is warranted to evaluate secondary outcomes such as postoperative pain, paresthesias, and pain medication requirements.
Funding Statement
Funding None.
Footnotes
Conflict of Interest None declared.
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