Kristopher B. Williams

Arterial vs venous blood gas differences during hemorrhagic shock

AIM To characterize differences of arterial (ABG) and venous (VBG) blood gas analysis in a rabbit model of hemorrhagic shock. METHODS Following baseline arterial and venous blood gas analysis, fifty anesthetized, ventilated New Zealand white rabbits were hemorrhaged to and maintained at a mean arterial pressure of 40 mmHg until a state of shock was obtained, as defined by arterial pH ≤ 7.2 and base deficit ≤ -15 mmol/L. Simultaneous ABG and VBG were obtained at 3 minute intervals. Comparisons of pH, base deficit, pCO2, and arteriovenous (a-v) differences were then made between ABG and VBG at baseline and shock states. Statistical analysis was applied where appropriate with a significance of P < 0.05. RESULTS All 50 animals were hemorrhaged to shock status and euthanized; no unexpected loss occurred. Significant differences were noted between baseline and shock states in blood gases for the following parameters: pH was significantly decreased in both arterial (7.39 ± 0.12 to 7.14 ± 0.18) and venous blood gases (7.35 ± 0.15 to 6.98 ± 0.26, P < 0.05), base deficit was significantly increased for arterial (-0.9 ± 3.9 mEq/L vs -17.8 ± 2.2 mEq/L) and venous blood gasses (-0.8 ± 3.8 mEq/L vs -15.3 ± 4.1 mEq/L, P < 0.05). pCO2 trends (baseline to shock) demonstrated a decrease in arterial blood (40.0 ± 9.1 mmHg vs 28.9 ± 7.1 mmHg) but an increase in venous blood (46.0 ± 10.1 mmHg vs 62.8 ± 15.3 mmHg), although these trends were non-significant. For calculated arteriovenous differences between baseline and shock states, only the pCO2 difference was shown to be significant during shock. CONCLUSION In this rabbit model, significant differences exist in blood gas measurements for arterial and venous blood after hemorrhagic shock. A widened pCO2 a-v difference during hemorrhage, reflective of poor tissue oxygenation, may be a better indicator of impending shock.

Impact of the Establishment of a Specialty Hernia Referral Center

Background. Creating a surgical specialty referral center requires a strong interest, expertise, and a market demand in that particular field, as well as some form of promotion. In 2004, we established a tertiary hernia referral center. Our goal in this study was to examine its impact on institutional volume and economics. Materials and methods. The database of all hernia repairs (2004-2011) was reviewed comparing hernia repair type and volume and center financial performance. The ventral hernia repair (VHR) patient subset was further analyzed with particular attention paid to previous repairs, comorbidities, referral patterns, and the concomitant involvement of plastic surgery. Results. From 2004 to 2011, 4927 hernia repairs were performed: 39.3% inguinal, 35.5% ventral or incisional, 16.2% umbilical, 5.8% diaphragmatic, 1.6% femoral, and 1.5% other. Annual billing increased yearly from 7% to 85% and averaged 37% per year. Comparing 2004 with 2011, procedural volume increased 234%, and billing increased 713%. During that period, there was a 2.5-fold increase in open VHRs, and plastic surgeon involvement increased almost 8-fold, (P = .004). In 2005, 51 VHR patients had a previous repair, 27.0% with mesh, versus 114 previous VHR in 2011, 58.3% with mesh (P < .0001). For VHR, in-state referrals from 2004 to 2011 increased 340% while out-of-state referrals jumped 580%. In 2011, 21% of all patients had more than 4 comorbidities, significantly increased from 2004 (P = .02). Conclusion. The establishment of a tertiary, regional referral center for hernia repair has led to a substantial increase in surgical volume, complexity, referral geography, and financial benefit to the institution.