Ricardo Prist

A quantitative analysis of transcapillary refill in severe hemorrhagic hypotension in dogs.

In pressure-driven hemorrhage (PDH), where the rate of bleeding is a function of prevailing arterial pressure, survival time, arterial pressure, cardiac output, oxygen consumption, and base excess are functions of initial bleeding rate. The quantitative rate of transcapillary refill (TR) throughout PDH leading to death was determined in splenectomized dogs, through serial analysis of Cr51-tagged red cell dilution. Mild, moderate, and severe levels of PDH were produced by varying initial bleeding rate (10, 25, and 50 ml/min, respectively). The rate of TR is a function of the severity of PDH, but does not correlate with arterial pressure, cardiac output, or systemic resistance. The volume of transferred fluid represents an ever increasing fraction of total plasma volume, and accounts for more than 75% of plasma volume in preterminal stages of shock. TR sustains a relatively fixed level of plasma volume, equivalent to two-third of the initial plasma volume, irrespective of the rate of bleeding. Hypertonic NaCI (7.5%) enhances TR, while isotonic NaCI reverses it.

ISOCHLOREMIC HYPERTONIC SOLUTIONS FOR SEVERE HEMORRHAGE

Two different hypertonic (2400 mOsm/L) isochloremic dextran solutions (sodium acetate, HAD; and sodium lactate, HLD; in 0.9% NaCl + 6% dextran 70) were compared with HSD (2400 mOsm/L NaCl + 6% dextran 70) as initial treatment for severe uninterrupted arterial bleeding. The substitution of dextran 70 for lactated Ringers solution as the maintenance isotonic infusion fluid was also analyzed. Experiments were performed in pentobarbital-anesthetized dogs. A recently developed model, pressure-driven hemorrhage (PDH), which mimics uninterrupted arterial bleeding, was employed. It was found that (1) the substitution of dextran 70 for lactated Ringers as isotonic fluid makes no difference in hemodynamic terms; (2) isochloremic hypertonic solutions are similar in their hemodynamic resuscitative effect, representing an improvement over hypertonic NaCl in terms of cardiac output, O2 delivery and O2 consumption; (3) HAD proved superior to HLD in terms of O2 consumption and correction of pH/base excess.

Size and spatial distribution of stray dog population in the University of São Paulo campus, Brazil

A longitudinal study was carried out to describe the size and spatial distribution of the stray dog population in the University of São Paulo campus, Brazil from November 2010 to November 2011. The campus is located within the urban area of São Paulo, the largest city of Brazil, with a population over 11 million. The 4.2 km(2) that comprise the university grounds are walled, with 10 access gates, allowing stray dogs to move in and out freely. Over 100,000 people and 50,000 vehicles circulate in the campus daily. Five observations were made during the study period, using a mark-resight method. The same route was performed in all observations, being traveled twice on each observation day. Observed animals were photographed and the sight coordinates were obtained using a GPS device. The estimated size of the stray dog population varied from 32 (CI 95% 23-56) to 56 (CI 95% 45-77) individuals. Differences between in- and outward dog movements influenced dog population estimates. Overlapping home ranges of docile dogs were observed in areas where most people circulate. An elusive group was observed close to a protected rain forest area and the estimated home range for this group did not overlap with the home ranges for other dogs within the campus. A kernel density map showed that higher densities of stray dog sighting is associated with large organic matter generators, such as university restaurants. We conclude that the preferred source of food of the stray dogs on the University of São Paulo campus was leftover food deliberately offered by restaurant users. The population was stable during the study period and the constant source of food was the main reason to retain this population within the campus.

Anesthetic induction after treated hemorrhagic shock: experimental study comparing ketamine and etomidate

JUSTIFICATIVA Y OBJETIVOS: El sangramiento que conlleva al choque hemorragico generalmente necesita un tratamiento quirurgico bajo anestesia general. A su vez, los anestesicos pueden comprometer mas las condiciones hemodinamicas. El objetivo de este estudio fue el de comparar los efectos hemodinamicos de la cetamina y del etomidato durante la induccion anestesica en perros sometidos a un modelo experimental de choque hemorragico y reanimacion. METODO: Treinta y dos perros mestizos fueron sometidos al choque hemorragico presion-controlada, reanimacion e induccion anestesica. Despues de alcanzar la presion objeto de 40 mmHg ellos fueron divididos aleatoriamente en dos grupos de acuerdo con el liquido usado en la resucitacion: NaCl a 0.9% (32 mL.kg-1) y NaCl a 7,5% (4 mL.kg-1). Despues de la infusion de volumen, esos grupos fueron divididos nuevamente de acuerdo con el anestesico utilizado: GI) NaCl a 0.9% y cetamina; GII) NaCl a 7.5% y cetamina; GIII) NaCl a 0.9% y etomidato; y GIV) NaCl a 7.5% y etomidato. Mediciones hemodinamicas fueron obtenidas en cinco momentos: (M0) inicial; (M1) despues del desarrollo del choque hemorragico; (M2) despues de la administracion de soluciones; (M3) 5 minutos despues de la induccion anestesica; (M4) 15 minutos despues de la induccion anestesica. Se hizo el analisis estadistico usando el Student t test y two-way ANOVA. Fueron considerados significativos valores de p menores que 0,05. RESULTADOS: Despues de la instalacion del choque, los dos sueros reestablecieron los estandares hemodinamicos a los valores iniciales. Independiente del anestesico o del solucion utilizada, despues de la induccion anestesica la presion arterial media permanecio inalterada en todos los grupos. La presion venosa central, frecuencia cardiaca, presion capilar pulmonar y el indice de resistencia pulmonar vascular aumentaron significativamente despues de la administracion de cetamina. El indice cardiaco, el indice de resistencia vascular sistemica y el transporte de oxigeno permanecieron estables en todos los grupos. CONCLUSIONES: El etomidato o la cetamina fueron capaces de mantener la estabilidad hemodinamica en los perros que sufrieron choque hemorragico severo y que fueron tratados con NaCl a 0,9% o NaCl a 7,5%.BACKGROUND AND OBJECTIVES Bleeding causing hemorrhagic shock usually requires surgical treatment under general anesthesia. Anesthetic drugs may further compromise hemodynamics. The objective was to compare the hemodynamic effects of ketamine and etomidate during anesthetic induction in dogs submitted to an experimental model of hemorrhagic shock and resuscitation. METHODS Thirty-two mongrel dogs were submitted to a pressure-controlled hemorrhagic shock, resuscitation and anesthetic induction model. After achieving the target pressure of 40 mmHg, they were randomly assigned in two groups according to the resuscitation fluid to be used: NaCl 0.9% (32 mL.kg-1) and NaCl 7.5% (4 mL.kg-1). After volume infusion, these groups were reassigned according to anesthetic drug used: GI) NaCl 0.9% and ketamine; GII) NaCl 7.5% and ketamine; GIII) NaCl 0.9% and etomidate; and GIV) NaCl 7.5% and etomidate. Hemodynamic measurements were obtained at five moments: (M0) baseline; (M1) after bleeding to shock; (M2) after volume expansion; (M3) 5 minutes after anesthetic induction; (M4) 15 minutes after anesthetic induction. Statistical analysis was performed using Student t test and two way ANOVA. Value of p lower than 0.05, was considered significant. RESULTS After shock, both solutions restored hemodynamics to baseline values. Independently of anesthetic agent or expansion solution used, mean arterial pressure remained unaltered for all groups after induction. Central venous pressure, heart rate, pulmonary capillary wedge pressure and pulmonary vascular resistance index increased significantly after ketamine infusion. Cardiac index, systemic vascular resistance index and oxygen transport variables remained stable in all groups. CONCLUSIONS Etomidate or ketamine were able to maintain hemodynamic stability in dogs undergoing severe hemorrhagic shock treated with NaCl 0.9% or NaCl 7.5%.

Short-term effects of hydroxyethylstarch resuscitation on systemic and regional hemodynamics and metabolism in a brain-dead canine model.

BACKGROUND Hydroxyethylstarch (HES) is a synthetic polymer of glucose that has been suggested for therapeutic use in long-term plasma expansion. The aim of this study was to test the hypothesis that the infusion of a small volume of HES may provide benefits in systemic and regional hemodynamics and metabolism in a brain-dead canine model compared with large volume crystalloid resuscitation. METHODS Fourteen mongrel dogs were subjected to a brain-death protocol by consecutive insufflations of a balloon catheter in the epidural space. One hour after induction of brain-death, the animals were randomly assigned to two groups: NS (0.9% NaCl, 33 mL/kg), and HES (6%HES 450/0.7, 17 mL/Kg). Systemic and regional hemodynamics were evaluated using Swan-Ganz, ultrasonic flowprobes, and arterial catheters. Serial blood samples were collected for blood gas, electrolyte, and serum chemistry analysis. Systemic, hepatic, and splanchnic O(2)-derived variables were also calculated. RESULTS Epidural balloon insufflations induced a significant increase in mean arterial pressure, cardiac output (MAP and CO, respectively), regional blood flow, and systemic vascular resistance. Following the hyperdynamic phase, severe hypotension with normalization of systemic and regional blood flow was observed. Fluid resuscitation induced a prompt increase in MAP, CO, and portal vein blood flow, and a significant reduction in systemic and pulmonary vascular resistance. There were no differences between groups in metabolic indices, liver function tests (LFTs), or renal function tests. HES was more effective than NS in restoring cardiac performance in the first 2h after fluid resuscitation (P < 0.05). Both tested solutions partially and temporarily restored systemic and regional oxygen delivery. CONCLUSION Small volumes of 6% HES 450/0.7 improved cardiovascular performance and provided the same regional hemodynamic and metabolic benefits of large volumes of isotonic crystalloid solutions.

Indução anestésica após o tratamento do choque hemorrágico: estudo experimental comparando a cetamina e o etomidato

JUSTIFICATIVA Y OBJETIVOS: El sangramiento que conlleva al choque hemorragico generalmente necesita un tratamiento quirurgico bajo anestesia general. A su vez, los anestesicos pueden comprometer mas las condiciones hemodinamicas. El objetivo de este estudio fue el de comparar los efectos hemodinamicos de la cetamina y del etomidato durante la induccion anestesica en perros sometidos a un modelo experimental de choque hemorragico y reanimacion. METODO: Treinta y dos perros mestizos fueron sometidos al choque hemorragico presion-controlada, reanimacion e induccion anestesica. Despues de alcanzar la presion objeto de 40 mmHg ellos fueron divididos aleatoriamente en dos grupos de acuerdo con el liquido usado en la resucitacion: NaCl a 0.9% (32 mL.kg-1) y NaCl a 7,5% (4 mL.kg-1). Despues de la infusion de volumen, esos grupos fueron divididos nuevamente de acuerdo con el anestesico utilizado: GI) NaCl a 0.9% y cetamina; GII) NaCl a 7.5% y cetamina; GIII) NaCl a 0.9% y etomidato; y GIV) NaCl a 7.5% y etomidato. Mediciones hemodinamicas fueron obtenidas en cinco momentos: (M0) inicial; (M1) despues del desarrollo del choque hemorragico; (M2) despues de la administracion de soluciones; (M3) 5 minutos despues de la induccion anestesica; (M4) 15 minutos despues de la induccion anestesica. Se hizo el analisis estadistico usando el Student t test y two-way ANOVA. Fueron considerados significativos valores de p menores que 0,05. RESULTADOS: Despues de la instalacion del choque, los dos sueros reestablecieron los estandares hemodinamicos a los valores iniciales. Independiente del anestesico o del solucion utilizada, despues de la induccion anestesica la presion arterial media permanecio inalterada en todos los grupos. La presion venosa central, frecuencia cardiaca, presion capilar pulmonar y el indice de resistencia pulmonar vascular aumentaron significativamente despues de la administracion de cetamina. El indice cardiaco, el indice de resistencia vascular sistemica y el transporte de oxigeno permanecieron estables en todos los grupos. CONCLUSIONES: El etomidato o la cetamina fueron capaces de mantener la estabilidad hemodinamica en los perros que sufrieron choque hemorragico severo y que fueron tratados con NaCl a 0,9% o NaCl a 7,5%.BACKGROUND AND OBJECTIVES Bleeding causing hemorrhagic shock usually requires surgical treatment under general anesthesia. Anesthetic drugs may further compromise hemodynamics. The objective was to compare the hemodynamic effects of ketamine and etomidate during anesthetic induction in dogs submitted to an experimental model of hemorrhagic shock and resuscitation. METHODS Thirty-two mongrel dogs were submitted to a pressure-controlled hemorrhagic shock, resuscitation and anesthetic induction model. After achieving the target pressure of 40 mmHg, they were randomly assigned in two groups according to the resuscitation fluid to be used: NaCl 0.9% (32 mL.kg-1) and NaCl 7.5% (4 mL.kg-1). After volume infusion, these groups were reassigned according to anesthetic drug used: GI) NaCl 0.9% and ketamine; GII) NaCl 7.5% and ketamine; GIII) NaCl 0.9% and etomidate; and GIV) NaCl 7.5% and etomidate. Hemodynamic measurements were obtained at five moments: (M0) baseline; (M1) after bleeding to shock; (M2) after volume expansion; (M3) 5 minutes after anesthetic induction; (M4) 15 minutes after anesthetic induction. Statistical analysis was performed using Student t test and two way ANOVA. Value of p lower than 0.05, was considered significant. RESULTS After shock, both solutions restored hemodynamics to baseline values. Independently of anesthetic agent or expansion solution used, mean arterial pressure remained unaltered for all groups after induction. Central venous pressure, heart rate, pulmonary capillary wedge pressure and pulmonary vascular resistance index increased significantly after ketamine infusion. Cardiac index, systemic vascular resistance index and oxygen transport variables remained stable in all groups. CONCLUSIONS Etomidate or ketamine were able to maintain hemodynamic stability in dogs undergoing severe hemorrhagic shock treated with NaCl 0.9% or NaCl 7.5%.

Effect of volume replacement during combined experimental hemorrhagic shock and traumatic brain injury in prostanoids, brain pathology and pupil status

Traumatic brain injury (TBI) is the main cause of trauma-related deaths. Systemic hypotension and intracranial hypertension causes cerebral ischemia by altering metabolism of prostanoids. We describe prostanoid, pupilar and pathological response during resuscitation with hypertonic saline solution (HSS) in TBI. Method Fifteen dogs were randomized in three groups according to resuscitation after TBI (control group; lactated Ringers (LR) group and HSS group), with measurement of thromboxane, prostaglandin, macroscopic and microscopic pathological evaluation and pupil evaluation.Result Concentration of prostaglandin is greater in the cerebral venous blood than in plasma and the opposite happens with concentration of thromboxane. Pathology revealed edema in groups with the exception of group treated with HSS.Discussion and conclusion There is a balance between the concentrations of prostaglandin and thromboxane. HSS prevented the formation of cerebral edema macroscopically detectable. Pupillary reversal occurred earlier in HSS group than in LR group.

Systemic and regional hemodynamic and metabolic changes in an experimental model of brain death

Despite the evolution of transplant techniques, the great number of donated organs continues to proceed from donors in brain death (BD). The need for stabilization in patients with BD, in the view of the triggered autonomic storm, is basic in such a way that knowledge of the physiopathologic, hemodynamic and metabolic disturbances becomes essential.

Inducción anestésica después del tratamiento del choque hemorrágico: estudio experimental eomparando la cetamina y el etomidato

JUSTIFICATIVA Y OBJETIVOS: El sangramiento que conlleva al choque hemorragico generalmente necesita un tratamiento quirurgico bajo anestesia general. A su vez, los anestesicos pueden comprometer mas las condiciones hemodinamicas. El objetivo de este estudio fue el de comparar los efectos hemodinamicos de la cetamina y del etomidato durante la induccion anestesica en perros sometidos a un modelo experimental de choque hemorragico y reanimacion. METODO: Treinta y dos perros mestizos fueron sometidos al choque hemorragico presion-controlada, reanimacion e induccion anestesica. Despues de alcanzar la presion objeto de 40 mmHg ellos fueron divididos aleatoriamente en dos grupos de acuerdo con el liquido usado en la resucitacion: NaCl a 0.9% (32 mL.kg-1) y NaCl a 7,5% (4 mL.kg-1). Despues de la infusion de volumen, esos grupos fueron divididos nuevamente de acuerdo con el anestesico utilizado: GI) NaCl a 0.9% y cetamina; GII) NaCl a 7.5% y cetamina; GIII) NaCl a 0.9% y etomidato; y GIV) NaCl a 7.5% y etomidato. Mediciones hemodinamicas fueron obtenidas en cinco momentos: (M0) inicial; (M1) despues del desarrollo del choque hemorragico; (M2) despues de la administracion de soluciones; (M3) 5 minutos despues de la induccion anestesica; (M4) 15 minutos despues de la induccion anestesica. Se hizo el analisis estadistico usando el Student t test y two-way ANOVA. Fueron considerados significativos valores de p menores que 0,05. RESULTADOS: Despues de la instalacion del choque, los dos sueros reestablecieron los estandares hemodinamicos a los valores iniciales. Independiente del anestesico o del solucion utilizada, despues de la induccion anestesica la presion arterial media permanecio inalterada en todos los grupos. La presion venosa central, frecuencia cardiaca, presion capilar pulmonar y el indice de resistencia pulmonar vascular aumentaron significativamente despues de la administracion de cetamina. El indice cardiaco, el indice de resistencia vascular sistemica y el transporte de oxigeno permanecieron estables en todos los grupos. CONCLUSIONES: El etomidato o la cetamina fueron capaces de mantener la estabilidad hemodinamica en los perros que sufrieron choque hemorragico severo y que fueron tratados con NaCl a 0,9% o NaCl a 7,5%.BACKGROUND AND OBJECTIVES Bleeding causing hemorrhagic shock usually requires surgical treatment under general anesthesia. Anesthetic drugs may further compromise hemodynamics. The objective was to compare the hemodynamic effects of ketamine and etomidate during anesthetic induction in dogs submitted to an experimental model of hemorrhagic shock and resuscitation. METHODS Thirty-two mongrel dogs were submitted to a pressure-controlled hemorrhagic shock, resuscitation and anesthetic induction model. After achieving the target pressure of 40 mmHg, they were randomly assigned in two groups according to the resuscitation fluid to be used: NaCl 0.9% (32 mL.kg-1) and NaCl 7.5% (4 mL.kg-1). After volume infusion, these groups were reassigned according to anesthetic drug used: GI) NaCl 0.9% and ketamine; GII) NaCl 7.5% and ketamine; GIII) NaCl 0.9% and etomidate; and GIV) NaCl 7.5% and etomidate. Hemodynamic measurements were obtained at five moments: (M0) baseline; (M1) after bleeding to shock; (M2) after volume expansion; (M3) 5 minutes after anesthetic induction; (M4) 15 minutes after anesthetic induction. Statistical analysis was performed using Student t test and two way ANOVA. Value of p lower than 0.05, was considered significant. RESULTS After shock, both solutions restored hemodynamics to baseline values. Independently of anesthetic agent or expansion solution used, mean arterial pressure remained unaltered for all groups after induction. Central venous pressure, heart rate, pulmonary capillary wedge pressure and pulmonary vascular resistance index increased significantly after ketamine infusion. Cardiac index, systemic vascular resistance index and oxygen transport variables remained stable in all groups. CONCLUSIONS Etomidate or ketamine were able to maintain hemodynamic stability in dogs undergoing severe hemorrhagic shock treated with NaCl 0.9% or NaCl 7.5%.

Intraneuronal calcium release after traumatic brain injury and hemorrhagic hypotension: a comparison between small-volume hypertonic saline and large-volume lactated Ringer's infusions

Calcium is one of the triggers involved in ischemic neuronal death. The injury can be truly delayed, even after cells repolarize and resume physiological and metabolic functions. Therefore, it would be reasonable to prevent calcium influx in early stages of traumatic brain injury (TBI). In the same way, hypertonic saline (7.5%NaCl) infused to hemorrhaged animals rapidly restores cardiac output and arterial pressure. Because hypotension is a strong predictor of outcome in TBI, we tested the hypothesis that hypertonic saline blunts calcium influx in hemorrhagic shock associated with head injury, compared with lactated Ringers.