Prophylactic Cefazolin Dosing and Surgical Site Infections: Does the Dose Matter in Obese Patients?

BACKGROUND: Most surgical prophylaxis guidelines recommend a 3-g cefazolin intravenous dose in patients weighing ≥ 120 kg. However, this recommendation is primarily based on pharmacokinetic studies rather than robust clinical evidence. This study aimed to compare the prevalence of surgical site infections (SSIs) in obese and non-obese patients (body mass index ≥ 30 kg/m2 and < 30 kg/m2), and those weighing ≥ 120 kg and < 120 kg, who received 2- g cefazolin preoperatively. METHODS: A retrospective case-control study was conducted in adult elective surgical patients. Patients receiving 2- g cefazolin were grouped as obese and non-obese, and by weight (≥ 120 kg or < 120 kg). The 90-day prevalence of SSI and potential contributing factors were investigated. RESULTS: We identified 152 obese (median 134 kg) and 152 non-obese control (median 73 kg) patients. Baseline characteristics were similar between groups, except for an increased prevalence in the obese group of diabetes (35.5% vs 13.2%; p < 0.001) and an American Society of Anaesthesiologists Score of 3 (61.8% vs 17.1%; p < 0.001). While not statistically significant, the prevalence of SSI in the obese group was almost double that in the non-obese group (8.6% vs 4.6%; p = 0.25) and in patients weighing ≥ 120 kg (n = 102) compared to those weighing < 120 kg (n = 202) (9.8% vs 5.0%; p = 0.17). CONCLUSION: The prevalence of SSI was not significantly increased in obese patients, or those weighing ≥ 120 kg, who received cefazolin 2- g prophylactically; however, trends toward an increase were evident. Large-scale randomised trials are needed to examine whether a 2-g or 3-g cefazolin is adequate to prevent SSI in obese (and ≥ 120 kg) individuals.

Comparison of plain x-rays and computed tomography for assessing distal radioulnar joint inclination.

PURPOSE: To compare the inclination of the distal radioulnar joint (DRUJ) on computed tomography (CT) and plain radiography (XR) in order to assess the effect of narrowing the range of inclination used in the original Tolat classification system to identify potentially problematic reverse oblique DRUJs. METHODS: Two independent investigators compared the angle of inclination and Tolat type on matched wrist XRs in the coronal plane and CTs of the same patients with normal DRUJs. The degree of agreement between XR and CT was determined. Inter- and intra-observer reliabilities were calculated. The prevalence of the 3 inclination types of the DRUJs using Tolat's definition was recorded. Their original quantitative definition of the parallel Tolat type 1 DRUJ included all DRUJs with a measured inclination of ±10°. We noted and compared the resultant changes in prevalence of the different DRUJ types after narrowing the inclination range to ±5° and ±3°. RESULTS: Highly significant correlation between CT and XR measurements were found for both observers. Despite this, the limits of agreement between CT and XR in determining the sigmoid notch inclination was -9° to 11° (±2° standard deviations from the mean difference). When measured from the CTs and using Tolat's original algorithm, the prevalence of Tolat type 1 DRUJ was 47% (N = 34), type 2 was 51% (N = 37), and type 3 was 1% (N = 1). These percentages changed to 7% (N = 5) for type 1, 78% (N = 56) for type 2, and 15% (N = 11) for type 3 when applying narrower ranges of inclination. CONCLUSIONS: Narrowing the range of sigmoid notch inclination that defines type 1 (parallel) DRUJs when using CT provided a more accurate representation of the morphological types. It revealed an increased number of potentially problematic type 3 DRUJs. However, the statistical limits of agreement between CT and XR suggested that high-resolution 3-dimensional imaging is required to apply the new algorithm. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.