Louis Riddez

Central and regional hemodynamics during acute hypovolemia and volume substitution in volunteers.

OBJECTIVES To study the central and regional hemodynamics and oxygen consumption during acute hypovolemia and volume replacement with crystalloid and colloid solutions. DESIGN Prospective, randomized, laboratory investigation. SETTING Clinical physiology department at a university hospital. SUBJECTS Eighteen healthy male volunteers, between 21 and 35 yrs of age (mean 26). INTERVENTIONS Catheters were inserted in the cubital vein, brachial artery, pulmonary artery, thoracic aorta, right hepatic vein, and left renal vein for measurements of systemic arterial and pulmonary arterial pressures, total and central blood volumes, extravascular lung water, and the splanchnic (liver) and renal blood flow rates. The exchange of respiratory gases was measured, using the Douglas bag technique. Measurements were made before and after a venesection of 900 mL and again after the subjects had been randomized and received volume replacement with either 900 mL of Ringers acetate solution 900 mL of albumin 5%, or 900 plus 900 mL of Ringers solution. MEASUREMENTS AND MAIN RESULTS Withdrawal of 900 mL of blood decreased cardiac output and the splanchnic and renal blood flow rates by between -16% and -20%. The oxygen uptake decreased by 13% in the whole body, while it remained unchanged in the liver and kidney. The systemic and pulmonary vascular resistances increased, while the extravascular lung water decreased. Autotransfusion of fluid from tissue to blood was indicated by hemodilution, which was most apparent in subjects showing only a minor change in peripheral resistance. Cardiac output, blood volume, and systemic vascular resistance were significantly more increased by infusion of 900 mL of albumin 5% than by 900 mL of Ringers solution. However, infusion of 1800 mL of Ringers solution increased the extravascular lung water and the pulmonary arterial pressures to significantly above baseline, while no significant difference from baseline was found after 900 mL of Ringers acetate solution. CONCLUSIONS Withdrawal of 900 mL of blood induces similar reductions in cardiac output as in the splanchnic and renal blood flow rates. A fluid shift from the extravascular to the intravascular fluid compartment might restore up to 50% of the blood loss. Optimal volume substitution with Ringers solution can be effectuated by infusing between 100% and 200% of the amount of blood lost.

Lower dose of hypertonic saline dextran reduces the risk of lethal rebleeding in uncontrolled hemorrhage.

To challenge whether the recommended dose of 4 mL/kg of 7.5% sodium chloride in 6% Dextran (HSD) is optimal for fluid resuscitation in uncontrolled hemorrhage, 30 anesthetized pigs were randomized to receive a 5-min intravenous infusion of either 1, 2, or 4 mL/kg of HSD beginning 10 min after inducing a 5-mm laceration in the infrarenal aorta. In addition to conventional hemodynamic monitoring, the blood loss was calculated as the difference in blood flow rates between flow probes placed proximal and distal to the injury. The results show that the bleeding stopped between 3 and 4 min after the injury and amounted to 338 ± 92 mL (mean ± SEM), which corresponds to 28.5% ± 6.6% of the estimated blood volume. After treatment with HSD was started, six rebleeding events occurred in the 1-mL group, 11 in the 2-mL group, and 16 in the 4-mL group. The amount of blood lost due to rebleeding increased significantly with the dose of HSD and was also associated with a fatal outcome. The total blood loss was 408 mL in the survivors and 630 mL in the nonsurvivors (median, P < 0.007). The mortality in the three groups was 20%, 50%, and 50%, respectively. In conclusion, infusing 4 mL/kg of HSD after uncontrolled aortic hemorrhage promoted rebleeding and increased the mortality, while a dose of 1 mL/kg appeared to be more suitable.

Assessment of hospital surge capacity using the MACSIM simulation system: a pilot study

AimThe aim of this study was to use a simulation model developed for the scientific evaluation of methodology in disaster medicine to test surge capacity (SC) in a major hospital responding to a simulated major incident with a scenario copied from a real incident.MethodsThe tested hospital was illustrated on a system of magnetic boards, where available resources, staff, and patients treated in the hospital at the time of the test were illustrated. Casualties were illustrated with simulation cards supplying all data required to determine procedures for diagnosis and treatment, which all were connected to real consumption of time and resources.ResultsThe first capacity-limiting factor was the number of resuscitation teams that could work parallel in the emergency department (ED). This made it necessary to refer severely injured to other hospitals. At this time, surgery (OR) and intensive care (ICU) had considerable remaining capacity. Thus, the reception of casualties could be restarted when the ED had been cleared. The next limiting factor was lack of ventilators in the ICU, which permanently set the limit for SC. At this time, there was still residual OR capacity. With access to more ventilators, the full surgical capacity of the hospital could have been utilized.ConclusionsThe tested model was evaluated as an accurate tool to determine SC. The results illustrate that SC cannot be determined by testing one single function in the hospital, since all functions interact with each other and different functions can be identified as limiting factors at different times during the response.

Impaired quality of life after bicycle trauma

INTRODUCTION Bicycle crashes often affect individuals in working age, and can impair quality of life (QoL) as a consequence. The aim of this study was to investigate QoL in bicycle trauma patients and to identify those at risk of impaired QoL. PATIENTS AND METHODS 173 bicycle trauma patients who attended a level I trauma centre from 2010 to 2012 received Hadorns QoL questionnaire six months after their crash. Medical data was collected from the patients records. Univariate ordinal logistic regression was used to investigate the association between QoL and other factors. RESULTS 148 patients returned the questionnaire (85.5%). The majority had only mild or minor injuries (85.1%; n=126). However, 72.1% (n=106) still suffered from pain or other physical symptoms more than six months after their bicycle crash. Patients with a Glasgow Coma Scale (GCS) ≤13 or an Injury Severity Score (ISS) >15 experienced impaired emotions/outlook on life (p-values 0.003 and 0.045, respectively). Physical suffering was reported by patients with a GCS ≤13 and in those with injuries to the cervical spine (p-values 0.02 and 0.025, respectively). Patients with an ISS >15 or facial fractures experienced limitations in daily activities (p-values 0.031 and 0.025, respectively). CONCLUSIONS More than 70% of bicycle trauma patients suffered physically more than six months after their crash, even though only 15% were severely injured. Risk factors for an impaired QoL were cervical spine injuries or facial fractures, a GCS ≤13 and an ISS >15.