Intraosseous Pressure Monitoring in Healthy Volunteers.

STUDY OBJECTIVE: Invasively monitoring blood pressure through the IO device has not been thoroughly demonstrated. This study attempted to establish baseline values of IO pressure in a healthy human population. METHODS: This was a prospective, healthy volunteer, observational study. Participants had two IO devices placed (humerus and tibia), and participant IO pressures, vital signs, and pain scores were monitored for up to 60 minutes. Participants were contacted at 24-hours and 7 days post-testing to assess for adverse events. Summary statistics were calculated for systolic, diastolic, and mean humeral and tibial IO pressure. The ratio of IO to non-invasive blood pressure was calculated, and Bland Altman plots were created. The slope (linear) of the mean humeral and the tibial IO pressures were also calculated. RESULTS: Fifteen subjects were enrolled between April and July 2015. Fourteen of 15 humeral IOs were placed successfully (93.3%) and all 15 of the tibial IOs were placed successfully. Mean tibial systolic, diastolic, and mean IO pressure were 55.8 ± 27.9, 49.3 ± 27.1, and 48.4 ± 29.4 mm Hg, respectively. Humeral systolic, diastolic, and mean IO pressure were 32.9 ± 16.0, 27.4 ± 15.2, and 24.5 ± 14.3 mm Hg. The mean tibial IO pressure was 52.5% ± 32.0% of external cuff pressure ratio. The mean humeral IO pressure was 26.5% ± 15.2% of the external mean blood pressure. The Bland Altman plots showed an inconsistent relationship between the systolic and diastolic cuff pressure and the IO pressures. We observed a 1% per minute decrease in IO pressure from the initial placement until the final reading. CONCLUSIONS: Intraosseous pressure readings can be obtained in healthy human volunteers. However, absolute IOP values were not consistent between subjects. Future research may determine how IO pressure can be used to guide therapy in ill and injured patients.

Botulinum toxin A-induced paralysis of the lateral abdominal wall after damage-control laparotomy: A multi-institutional, prospective, randomized, placebo-controlled pilot study.

BACKGROUND: Damage-control laparotomy (DCL) is a lifesaving operation used in critically ill patients; however, interval primary fascial closure remains a challenge. We hypothesized that flaccid paralysis of the lateral abdominal wall musculature induced by botulinum toxin A (BTX) would improve rates of primary fascial closure, decrease duration of hospital stay, and enhance pain control. METHODS: Consenting adults who had undergone a DCL at two institutions were prospectively randomized to receive ultrasound-guided injections of their external oblique, internal oblique, and transversus abdominus muscles with either BTX (150 mL, 2 U/mL) or placebo (150-mL 0.9% NaCl). Patients were excluded if they had a body mass index of greater than 50, remained unstable or coagulopathic, were home O2 dependent, or had an existing neuromuscular disorder. Outcomes were assessed in a double-blinded manner. Univariate and Kaplan-Meier estimates of cumulative probability of abdominal closure were performed. RESULTS: We randomized 46 patients (24 BTX, 22 placebo). There were no significant differences in demographics, comorbidities, and physiologic status. Injections were performed on average 1.8 ± 2.8 days (range, 0-14 days) after DCL. The 10-day cumulative probability of primary fascial closure was similar between groups: 96% for BTX (95% confidence interval [CI], 72-99%) and 93% for placebo (95% CI, 61-99%) (HR, 1.0; 95% CI, 0.5-1.8). No difference between BTX and placebo groups was observed for hospital length of stay (37 days vs. 26 days, p = 0.30) or intensive care unit length of stay (17 days vs. 11 days, p = 0.27). There was no difference in median morphine equivalents following DCL. The overall complication rate was similar (63% vs. 68%, p = 0.69), with two deaths in the placebo group and none in the BTX group. No BTX or injection procedure complications were observed. CONCLUSION: The use of BTX after DCL was safe but did not seem to affect primary fascial closure, hospital length of stay, or pain modulation after DCL. Given higher-than-expected rates of primary fascial closure, Type II error may have occurred. LEVEL OF EVIDENCE: Therapeutic study, level III.