DEFINITION
Results from profound impairment of cardiac function leading to a decrease in stroke volume and cardiac output, venous congestion, and peripheral vasoconstriction.
Cardiac dysfunction may be caused by hypertrophic or dilated cardiomyopathies, pericardial tamponade, outflow obstructions, thrombosis, severe endocardiosis, heartworm disease, or severe arrhythmias.
Cardiac “pump” failure may also be secondary to systemic diseases causing myocardial dysfunction such as sepsis.
Results in hypotension and compromised tissue perfusion, with reduced tissue oxygen delivery
Thursday, March 31, 2011
Sepsis and Bacteremia
DEFINITION
Bacteremia—defined as the presence of bacterial organisms in the bloodstream
Sepsis—systemic response to bacterial infection (e.g., fever, hypotension)
Terms are not synonymous, although often used interchangeably
PATHOPHYSIOLOGY
Shedding of bacterial organisms into the bloodstream—may occur transiently, intermittently, or continually
The most critical host response for elimination of bacteremia—provided by mononuclear phagocyte system of the spleen and liver; activation leads to release of numerous cellular mediators (cytokines), some of which are beneficial and others detrimental; may lead to death of the host
Neutrophils—relatively more important for defense against extravascular infection
Bacteremia—transient, subclinical event or may escalate to overt sepsis when the immune system is overwhelmed; generally of more pathologic significance when the bloodstream is invaded from venous or lymphatic drainage sites
Bacteremia—defined as the presence of bacterial organisms in the bloodstream
Sepsis—systemic response to bacterial infection (e.g., fever, hypotension)
Terms are not synonymous, although often used interchangeably
PATHOPHYSIOLOGY
Shedding of bacterial organisms into the bloodstream—may occur transiently, intermittently, or continually
The most critical host response for elimination of bacteremia—provided by mononuclear phagocyte system of the spleen and liver; activation leads to release of numerous cellular mediators (cytokines), some of which are beneficial and others detrimental; may lead to death of the host
Neutrophils—relatively more important for defense against extravascular infection
Bacteremia—transient, subclinical event or may escalate to overt sepsis when the immune system is overwhelmed; generally of more pathologic significance when the bloodstream is invaded from venous or lymphatic drainage sites
Salmonellosis
DEFINITION
A bacterial disease that causes enteritis, septicemia, and abortions and is caused by many different serotypes of Salmonella
PATHOPHYSIOLOGY
Salmonella—a gram-negative bacterium; colonizes the small intestine (ileum); adheres to and invades the enterocytes; eventually enters and multiplies in the lamina propria and local mesenteric lymph nodes; cytotoxin (cell death) and enterotoxin (increases cAMP) are produced; inflammation occurs; and prostaglandin synthesis ensues; results in secretory diarrhea and mucosal sloughing
Uncomplicated gastroenteritis—organisms are stopped at the mesenteric lymph node stage; patient has only diarrhea, vomiting, and dehydration
Bacteremia and septicemia following gastroenteritis—more serious disease; focal extraintestinal infections (abortion, joint disease) or endotoxemia may result; may lead to organ infarction, generalized thrombosis, DIC, and death
Some patients recover from the septicemic form but suffer prolonged recovery as a result of their debilitated state.
A bacterial disease that causes enteritis, septicemia, and abortions and is caused by many different serotypes of Salmonella
PATHOPHYSIOLOGY
Salmonella—a gram-negative bacterium; colonizes the small intestine (ileum); adheres to and invades the enterocytes; eventually enters and multiplies in the lamina propria and local mesenteric lymph nodes; cytotoxin (cell death) and enterotoxin (increases cAMP) are produced; inflammation occurs; and prostaglandin synthesis ensues; results in secretory diarrhea and mucosal sloughing
Uncomplicated gastroenteritis—organisms are stopped at the mesenteric lymph node stage; patient has only diarrhea, vomiting, and dehydration
Bacteremia and septicemia following gastroenteritis—more serious disease; focal extraintestinal infections (abortion, joint disease) or endotoxemia may result; may lead to organ infarction, generalized thrombosis, DIC, and death
Some patients recover from the septicemic form but suffer prolonged recovery as a result of their debilitated state.
Rotavirus Infections
OVERVIEW
Nonenveloped, double-stranded RNA virus; rota (Latin; “wheel”) for shape of the capsid; genus within the family Reoviridae; relatively resistant to environmental destruction (acid and lipid solvents); unique double-capsid protects virus from inactivation in the upper gastrointestinal tract.
Wide host range, identified in almost every species investigated
Most significant cause of severe gastro-enteritis in young children (< 2 years) and animals throughout the world
Transmission—fecal–oral contamination
Infection—affects mature epithelial cells on luminal tips of the intestinal villi; causes swelling, degeneration, and desquamation; denuded villi contract; results in villous atrophy with loss of absorptive capability and loss of brush border enzymes (e.g., disaccharidases); leads to osmotic diarrhea
Nonenveloped, double-stranded RNA virus; rota (Latin; “wheel”) for shape of the capsid; genus within the family Reoviridae; relatively resistant to environmental destruction (acid and lipid solvents); unique double-capsid protects virus from inactivation in the upper gastrointestinal tract.
Wide host range, identified in almost every species investigated
Most significant cause of severe gastro-enteritis in young children (< 2 years) and animals throughout the world
Transmission—fecal–oral contamination
Infection—affects mature epithelial cells on luminal tips of the intestinal villi; causes swelling, degeneration, and desquamation; denuded villi contract; results in villous atrophy with loss of absorptive capability and loss of brush border enzymes (e.g., disaccharidases); leads to osmotic diarrhea
Rhinitis and Sinusitis
DEFINITION
Rhinitis—inflammation of the mucous membrane of the nose
Sinusitis—inflammation of the associated paranasal sinuses
Rhinosinusitis—coined term, because one rarely occurs without the other
PATHOPHYSIOLOGY
May be acute or chronic, noninfectious or infectious
Patients seen in clinics usually have chronic disease.
All causes are often complicated by opportunistic secondary microbial invasion.
Associated mucosal vascular congestion and friability, excessive mucus gland secretion, neutrophil chemotaxis, and nasolacrimal duct obstruction—lead to congestion, obstructed airflow, sneezing, epistaxis, nasal discharge (mucopurulent), and epiphora
Turbinate and facial bone destruction—may develop with neoplastic or fungal disease
Rhinitis—inflammation of the mucous membrane of the nose
Sinusitis—inflammation of the associated paranasal sinuses
Rhinosinusitis—coined term, because one rarely occurs without the other
PATHOPHYSIOLOGY
May be acute or chronic, noninfectious or infectious
Patients seen in clinics usually have chronic disease.
All causes are often complicated by opportunistic secondary microbial invasion.
Associated mucosal vascular congestion and friability, excessive mucus gland secretion, neutrophil chemotaxis, and nasolacrimal duct obstruction—lead to congestion, obstructed airflow, sneezing, epistaxis, nasal discharge (mucopurulent), and epiphora
Turbinate and facial bone destruction—may develop with neoplastic or fungal disease
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