ABSTRACT
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.
ABSTRACT
UNLABELLED: Previous studies have identified pain during needle/catheter placement or during the injection of local anesthetic as a risk factor for the development of persistent paresthesias after regional anesthetic techniques. The performance of regional blockade on anesthetized patients theoretically increases the risk of postoperative neurologic complications, because these patients are unable to respond to painful stimuli. In this study, we evaluated the frequency of neurologic complications in 4298 thoracic surgical patients undergoing lumbar epidural catheter placement while under general anesthesia. Catheters were placed immediately after the induction and tracheal intubation or on completion of the surgical procedure, before emergence. Most epidural catheters (4220, or 98.2%) were used solely for postoperative analgesia; only 78 (1.8%) epidural catheters were used for intraoperative anesthesia. In 4239 (98.6%) patients, an opioid alone was administered. The remaining 56 (1.3%) patients received a local anesthetic or local anesthetic/opioid mixture epidurally. Analgesia was graded as excellent or good in 92.2% of patients. Side effects included sedation in 455 (10.6%), nausea or emesis in 328 (7.6%), pruritus in 116 (2.7%), and respiratory depression (pH
