Session XI - Tibia

Sat., 10/7/06 Tibia, Paper #61, 10:57 am

Diastolic Blood Pressure in Patients with Tibia Fractures Under Anesthesia: Implications for the Diagnosis of Compartment Syndrome

Paul Tornetta III, MD (n); Reza Firoozabadi, MD (n);
Jason McKeon, MD (n); Sanjeev Kakar, MD (n);
Boston University Medical Center, Boston, Massachusetts, USA

Introduction: Compartment syndrome (CS) in the leg is difficult to diagnose in obtunded or anesthetized patients. The diagnosis is commonly made by direct compartment pressure (CP) measurements, with CS being defined as a DP <30 mmHg from the diastolic pressure. In patients under anesthesia, the systolic and diastolic blood pressure (DBP) may be lowered, leading to a lower DP given the same CP.

Purpose: The purpose of this paper is to examine the relationship of preoperative, intraoperative, and postoperative blood pressures in patients with tibia fractures as it relates to the diagnosis of CS using DP (DBP­CP).

Methods: The records of 246 consecutive patients with a tibia fracture treated with an intramedullary (IM) nail under general anesthesia were reviewed and their blood pressures preoperatively, intraoperatively, and postoperatively were documented (high, low, mean in each location). There were 190 males and 56 females aged 16 to 87 (average 39), with 126 open and 120 closed tibia fractures (49 proximal, 87 midshaft, 110 distal). The average ISS was 14.7 (range, 9 to 41).

Results: Anesthetized patients had a significant drop in their DBP and systolic blood pressure (SBP) as compared with their preoperative, postanesthesia care unit (PACU), and postoperative floor measurements (see table, in mmHg). The mean DBP in the operating room was 18 ± 13 mmHg lower than the preoperative measurement, while the difference in the preoperative and postoperative mean DBP was only 2 ± 13 mmHg.

   Preoperative  Intraoperative  PACU Inpatient Floor 
 SBP   134 ± 16  113 ± 12  142 ± 18  133 ± 16
 DBP  74 ± 10  56 ± 11  73 ± 11  76 ± 9


Discussion: In anesthetized patients undergoing IM nailing of the tibia, objective methods of diagnosing CS are needed as symptoms cannot be elicited. The most common method is direct measurement of the CP, with the diagnosis of CS being made based on the DP between the DBP and the CP. This series of patients with tibia fractures demonstrates that there is a discernable drop in the DBP that occurs in the operating room, and more importantly that the postoperative DBP returns to approximately the same level as that seen preoperatively, and that this level is maintained on the floor. Thus if the intraoperative DBP is utilized in calculating DP, this is likely to represent a lower number than will be the case once the patient is out of the operating room and not under anesthesia. In making the diagnosis of CS in the operating room, the preoperative DBP should be taken into account. Likewise, the time that the patient will be under anesthesia should be considered.

Conclusion: There is a predictable response of DBP in patients with tibia fractures treated with IM nailing under general anesthesia. The preoperative DBP is a good indicator of the postoperative DBP, and the intraoperative DBP is significantly lower (average 18mm Hg, P <0.05). The surgeon should recognize that intraoperative DP may be lower than DP once the patient is awakened in deciding whether to perform a fasciotomy or awaken the patient and perform serial examinations and/or CP measurements. Intraoperative DP may be spuriously low as compared with that after the patient is awakened.

If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.
· The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an "off label" use). · · FDA information not available at time of printing.