Some lessons learned from the COVID-19 pandemic: Subjective well-being before and during the pandemic among Brazilian adults

Image, graphical abstract.

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 Ringer's (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.

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.]

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%.

Initial hepatosplanchnic blood flow distribution and oxygen metabolism in experimental model of hypotensive brain death

BACKGROUND

Organs from the so-called marginal donors have been used with a significant higher risk of primary non function than organs retrieved from the optimal donors. We investigated the early metabolic changes and blood flow redistribution in splanchnic territory in an experimental model that mimics marginal brain-dead (BD) donor.

MATERIAL/METHODS

Ten dogs (21.3+/-0.9 kg), were subjected to a brain death protocol induced by subdural balloon inflation and observed for 30 min thereafter without any additional interventions. Mean arterial and intracranial pressures, heart rate, cardiac output (CO), portal vein and hepatic artery blood flows (PVBF and HABF, ultrasonic flowprobe), and O(2)-derived variables were evaluated.

RESULTS

An increase in arterial pressure, CO, PVBF and HABF was observed after BD induction. At the end, an intense hypotension with normalization in CO (3.0+/-0.2 vs. 2.8+/-2.8 L/min) and PVBF (687+/-114 vs. 623+/-130 ml/min) was observed, whereas HABF (277+/-33 vs. 134+/-28 ml/min, p<0.005) remained lower than baseline values.

CONCLUSIONS

Despite severe hypotension induced by sudden increase of intracranial pressure, the systemic and splanchnic blood flows were partially preserved without signs of severe hypoperfusion (i.e. hyperlactatemia). Additionally, the HABF was mostly negatively affected in this model of marginal BD donor. Our data suggest that not only the cardiac output, but the intrinsic hepatic microcirculatory mechanism plays a role in the hepatic blood flow control after BD.

Volume replacement with lactated Ringer's or 3% hypertonic saline solution during combined experimental hemorrhagic shock and traumatic brain injury

BACKGROUND

The devastating effects of hypotension on head-trauma-related mortality are well known. This study evaluates the systemic and cerebral hemodynamic responses to volume replacement with 3% hypertonic saline (HSS) or lactated Ringer's solution (LR), during the acute phase of hemorrhagic shock (HS) associated with traumatic brain injury (TBI).

METHODS

Fifteen dogs were assigned to one of three groups (n = 5, each) according to the volume replacement protocol, infused after TBI (brain fluid percussion, 4 atm) and epidural balloon to an intracranial pressure (ICP) higher than 20 mm Hg and HS, induced by blood removal to a mean arterial pressure (MAP) of 40 mm Hg in 5 minutes: Group HS+TBI+HSS (8 mL/kg of 3% HSS), HS+TBI+LR (16 mL/kg LR), and Group HS+TBI (controls, no fluids). We simulated treatment during prehospital and early hospital admission. Groups HS+ TBI and HS+TBI+LR received shed blood infusion to a target hematocrit of 30%. Measurements included shed blood volume, fluid volume infused to restore MAP, MAP, cardiac output, cerebral perfusion pressure, cerebral and systemic lactate, and oxygen extraction ratios.

RESULTS

Fluid replacement with HSS 3% or LR promoted major hemodynamic benefits over control animals without luids. Cerebral perfusion pressure was higher than controls and similar between treated groups; however, HSS 3% infusion was associated with lower ICP during the "early hospital phase" and a higher serum sodium and osmolarity.

CONCLUSION

In the event of severe head trauma and hemorrhagic shock, the use of HSS 3% and larger volumes of LR promote similar systemic and cerebral hemodynamic benefits. However, a lower ICP was observed after HSS 3% than after LR.

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 NaCl (7.5%) enhances TR, while isotonic NaCl 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 Ringer's 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 Ringer's 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.

Physical and physiological characteristics of pressure-driven hemorrhage

Research on hemorrhage has concentrated on its effects rather than the manner of occurrence. A new experimental method in which the rate of bleeding is a function of prevailing arterial pressure is proposed and described. The effects of standard crystalloid volume expansion and of small volume hypertonic treatment on this protocol are demonstrated. In pressure-driven hemorrhage, survival time and the decay of arterial pressure, cardiac output, oxygen consumption, and base excess are functions of the bleeding rate, but plasma proteins and hematocrits are independent. The decay of arterial pressure is also a complex function of blood volume deficit, but this relation is not dependent on the rate of blood removal. Volume expansion induces a recovery of circulatory function despite enhanced blood loss. A comparison between equiosmolar solutions of hypertonic sodium chloride and acetate shows that acetate produces a smaller pressor (hence less blood loss) but larger blood flow (hence higher O2 availability) effect. The possible importance of the isochloremic nature of the response to acetate is highlighted.

Pressure-driven hemorrhage: a new experimental design for the study of crystalloid and small-volume hypertonic resuscitation in anesthetized dogs

Fifty pentobarbital anesthetized dogs were subjected to pressure driven hemorrhage (PDH) in which (a) an initial bleeding rate (25 ml/min) was set, and (b) reset min-to-min in proportion to prevailing mean arterial pressure (MAP). When blood loss reached 40 ml/kg, experimental time was set to zero and dogs were divided into five groups: (1) CTR (untreated controls); (2) HSD (NaCl 7.5%-Dextran70 6%, 6 ml/kg, at zero time); (3) LR (lactated Ringers, 25 ml/min from 0-60 min); (4) HSD-LR (combines HSD and LR); (5) DBL-HSD-LR (as HSD-LR, plus second HSD injection, 4 ml/kg, at 30 min). PDH was continued throughout the postresuscitation period. CTR dogs bled 55.5 +/- 2.1 ml/kg and survived to 34.7 +/- 5.0 min postzero; HSD dogs bled 78.6 +/- 2.0 ml/kg, and survived to 51.2 +/- 2.9 min with transient recovery of MAP, cardiac output (CO), and O2 availability (O2A); LR dogs bled 94.5 +/- 3.4 ml/kg and survived for over 60 min, with sustained, partial recovery of MAP, CO, and O2A. HSD-LR dogs bled 111.5 +/- 3.7 ml/kg and survived for over 60 min with improved hemodynamic and metabolic response. In DBL-HSD-LR dogs, the second HSD produced higher MAP, CO, and O2A, but hematocrit was lowered to a critical level. Thus, standard LR resuscitation is effective in PDH, in spite of increased blood loss; a single HSD lengthens survival when used alone and improves recovery when added to LR.