Left ventricular compressions improve return of spontaneous circulation and hemodynamics in a swine model of traumatic cardiopulmonary arrest.

BACKGROUND: Prehospital cardiopulmonary resuscitation, including closed chest compressions, has commonly been considered ineffective in traumatic cardiopulmonary arrest (TCPA) because traditional chest compressions do not produce substantial cardiac output. However, recent evidence suggests that chest compressions located over the left ventricle (LV) produce greater hemodynamics when compared to traditional compressions. We hypothesized that chest compressions located directly over the LV would improve return of spontaneous circulation (ROSC) and hemodynamics when compared with traditional chest compressions, in a swine model of TCPA. METHODS: Transthoracic echocardiography was used to mark the location of the aortic root (traditional compressions), and the center of the LV on animals (n = 26) which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation was induced. After 10 minutes of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 minutes followed by advanced life support (ALS) for an additional 10 minutes. During BLS, the area of maximal compression was verified using transesophageal echocardiography. Hemodynamic variables were averaged over the final 2 minutes of the BLS and ALS periods. RESULTS: Five (38%) of the LV group achieved ROSC compared with zero of the aortic root group (p = 0.04). Additionally, there was an increase in aortic systolic blood pressure (SBP), aortic diastolic blood pressure (DBP) and coronary perfusion pressure (CPP) at the end of both the BLS (95% confidence interval, SBP, -49 to -21; DBP, -14 to -5.6; and CPP, -15 to -7.4) and ALS (95% confidence interval: SBP, -66 to -21; DBP, -49 to -6.8; and CPP, -51 to -7.5) resuscitation periods among the LV group. CONCLUSION: In our swine model of TCPA, chest compressions performed directly over the LV improved ROSC and hemodynamics when compared with traditional chest compressions.

Efficacy of Intravenous Cobinamide Versus Hydroxocobalamin or Saline for Treatment of Severe Hydrogen Sulfide Toxicity in a Swine (Sus scrofa) Model.

BACKGROUND: Hydrogen sulfide (H2 S) is a potentially deadly gas that naturally occurs in petroleum and natural gas. The Occupational Health and Safety Administration cites H2 S as a leading cause of workplace gas inhalation deaths. Mass casualties of H2 S toxicity may be caused by exposure from industrial accidents or release from oil field sites. H2 S is also an attractive terrorism tool because of its high toxicity and ease with which it can be produced. Several potential antidotes have been proposed for hydrogen sulfide poisoning but none have been completely successful. OBJECTIVE: The objective was to compare treatment response assessed by the time to spontaneous ventilation among groups of swine with acute H2 S-induced apnea treated with intravenous (IV) cobinamide (4 mg/kg in 0.8 mL of 225 mmol/L solution), IV hydroxocobalamin (4 mg/kg in 5 mL of saline), or saline alone. METHODS: Twenty-four swine (45-55 kg) were anesthetized, intubated, and instrumented with continuous femoral and pulmonary artery pressure monitoring. After stabilization, anesthesia was adjusted such that animals would spontaneously ventilate with an FiO2 of 0.21. Sodium hydrosulfide (NaHS; concentration of 8 mg/mL) was begun at 1 mg/kg/min until apnea was confirmed for 20 seconds by capnography. This infusion rate was sustained for 1.5 minutes postapnea and then decreased to a maintenance rate for the remainder of the study to replicate sustained clinical exposure. Animals were randomly assigned to receive cobinamide (4 mg/kg), hydroxocobalamin (4 mg/kg), or saline and monitored for 60 minutes beginning 1 minute postapnea. G* power analysis using the Z-test determined that equal group sizes of eight animals were needed to achieve a power of 80% in detecting a 50% difference in return to spontaneous ventilations at α = 0.05. RESULTS: There were no significant differences in baseline variables. Moreover, there were no significant differences in the mg/kg dose of NaHS (5.6 mg/kg; p = 0.45) required to produce apnea. Whereas all of the cobinamide-treated animals survived (8/8), none of the control (0/8) or hydroxocobalamin (0/8)-treated animals survived. Mean (±SD) time to spontaneous ventilation in the cobinamide-treated animals was 3.2 (±1.1) minutes. CONCLUSIONS: Cobinamide successfully rescued the severely NaHS-poisoned swine from apnea in the absence of assisted ventilation.

Intraosseous hydroxocobalamin versus intravenous hydroxocobalamin compared to intraosseous whole blood or no treatment for hemorrhagic shock in a swine model.

OBJECTIVE: To determine if intraosseous (IO) hydroxocobalamin can improve systolic blood pressure (SBP) in a swine model after severe hemorrhagic shock. METHODS: Thirty six swine (45-55 kg) were anesthetized, intubated, and instrumented with continuous femoral and pulmonary artery pressure monitoring and then hemorrhaged such that 30 percent of their blood volume was extracted over 20 minutes. Five minutes later, animals were randomly assigned to receive 500 mL IO whole blood, 150 mg/kg IO or intravenous (IV) hydroxocobalamin in 180 mL of saline, or no treatment and then monitored for 60 minutes. A sample size of eight animals per group was based on a power of 80 percent, an alpha of 0.05, and a small effect size to detect a difference in SBP between groups. Outcome data were analyzed using repeated measures analysis of variance (RMANOVA). RESULTS: RMANOVA outcome analysis detected a significant difference between groups (p < 0.05). IO whole blood, IO hydroxocobalamin, and IV hydroxocobalamin groups were similar to each other, but significantly different compared to controls regarding SBP, mean arterial pressure (MAP), systemic vascular resistance, and heart rate. Differences in SBP and MAP were sustained throughout the experiment. At 60 minutes, the comparison among the groups, IO whole blood, IO hydroxocobalamin, IV hydroxocobalamin, and control, was the following: SBP 78.2 versus 83.7 versus 75.1 versus 55.3 mm Hg; MAP 62.7 versus 65 versus 60 versus 43 mm Hg. There was a significant interaction by time in lactate values (p < 0.01) such that control animal lactate values increased over time (3.3 mmol/L) compared to IO whole blood, IO or IV hydroxocobalamin treated animals (1.1, 1.6, 1.3 mmol/L). CONCLUSIONS: IO hydroxocobalamin improved SBP, MAP, compared to no treatment and was similar to IO whole blood and IV hydroxocobalamin in this animal model of severe hemorrhage. Moreover, whereas serum lactate was improving in all treated groups, it was deteriorating in the control group.

Intraosseous versus intravenous infusion of hydroxocobalamin for the treatment of acute severe cyanide toxicity in a Swine model.

OBJECTIVES: Easily administrated cyanide antidotes are needed for first responders, military troops, and emergency department staff after cyanide exposure in mass casualty incidents or due to smoke inhalation during fires involving many victims. Hydroxocobalamin has proven to be an effective antidote, but cannot be given intramuscularly because the volume of diluent needed is too large. Thus, intraosseous (IO) infusion may be an alternative, as it is simple and has been recommended for the administration of other resuscitation drugs. The primary objective of this study was to compare the efficacy of IO delivery of hydroxocobalamin to intravenous (IV) injection for the management of acute cyanide toxicity in a well-described porcine model. METHODS: Twenty-four swine (45 to 55 kg) were anesthetized, intubated, and instrumented with continuous mean arterial pressure (MAP) and cardiac output monitoring. Cyanide was continuously infused until severe hypotension (50% of baseline MAP), followed by IO or IV hydroxocobalamin treatment. Animals were randomly assigned to receive IV (150 mg/kg) or IO (150 mg/kg) hydroxocobalamin and monitored for 60 minutes after start of antidotal infusion. The primary outcome measure was the change in MAP after antidotal treatment from onset of hypotension (time zero) to 60 minutes. A sample size of 12 animals per group was determined by group size analysis based on power of 80% to detect a one standard deviation of the mean MAP between the groups with an alpha of 0.05. Whole blood cyanide, lactate, pH, nitrotyrosine (nitric oxide marker) levels, cerebral and renal near infrared spectrometry (NIRS) oxygenation, and inflammatory markers were also measured. Repeated-measures analysis of variance was used to determine statistically significant changes between groups over time. RESULTS: At baseline and at the point of hypotension, physiologic parameters were similar between groups. At the conclusion of the study, 10 out of 12 animals in the IV group and 10 out of 12 in IO group survived (p = 1.0). Both groups demonstrated a similar return to baseline MAP (p = 0.997). Cardiac output, oxygen saturation, and systemic vascular resistance were also found to be similar between groups (p > 0.4), and no difference was detected between bicarbonate, pH, and lactate levels (p > 0.8). Cyanide levels were undetectable after the hydroxocobalamin infusion throughout the study in both groups (p = 1.0). Cerebral and renal NIRS oxygenation decreased in parallel to MAP during cyanide infusion and increased after antidote infusion in both groups. Serum nitrotyrosine increased during cyanide infusion in all animals and then decreased in both study arms after hydroxocobalamin infusion (p > 0.5). Serum cytokines increased starting at cyanide infusion and no difference was detected between groups (tumor necrosis factor-α, interleukin [IL]-1ß, IL-6, and IL-10). CONCLUSIONS: The authors found no difference in the efficacy of IV versus IO hydroxocobalamin in the treatment of severe cyanide toxicity in a validated porcine model.

Surgical cancellations: a review of elective surgery cancellations in a tertiary care pediatric institution.

The purpose of this two-phase quality improvement audit was to analyze elective surgery cancellations in a tertiary pediatric care institution and identify and recommend nursing practice changes in the preoperative assessment clinic (POAC) to potentially influence the overall cancellation rate. A prospective review of cancellation data was conducted over a 6-month period in 2008 and again in 2010. In both phases of the audit, illness was the leading cause for surgical cancellation between the preoperative assessment and the day of surgery, with otolaryngology service representing the highest number of cancellations. Cancellations at or between the preoperative assessment and the day of surgery may be viewed as POAC successes that may have otherwise increased the day-of-surgery cancellation rate. Educating families on the prevention of illness in the perianesthesia period may be a critical nursing role in the prevention of surgical cancellations.