Sepsis and Septic Shock

Pneumonia in pregnancy

Pneumonia occurs in the pregnant population with a frequency equal to that in the general population. However, its course is often more virulent, and mortality rates from certain pathogens may be high. The pregnant woman is more susceptible to injury to the respiratory tract due to a number of factors. These include alterations in the immune system which involve cell-mediated immunity and mechanical and anatomical changes involving the chest and abdominal cavities. The cumulative effect is decreased tolerance of hypoxia and acute changes in pulmonary mechanics. The spectrum of pathogens is similar to that for nonpregnant individuals, and the management of pneumonia in pregnancy does not differ in general from the nonpregnant state. However, careful attention should be paid to the fetoplacental unit with delivery generally indicated for obstetric purposes only. Issues that also need to be addressed include effects of certain infections, medications, fever, and hypoxia on the developing fetus.

Beneficial effects of pre-treatment with vitamin A on cardiac and pulmonary functions in endotoxaemic pigs

BACKGROUND

Septic shock is associated with high mortality despite the development of new antibiotics. Since Vitamin A has an immunomodulating ability and is able to lower the concentrations of endotoxin and some cytokines, we decided to study whether supplementation with vitamin A may have a beneficial effect in experimental endotoxaemia.

METHODS

A porcine model was used, in which normally bred (i.e., not vitamin A depleted) animals were anaesthetised, monitored and injected intramuscularly with a non-toxic dose of vitamin A (230 IU.kg-1) (n = 9) or the corresponding volume of vehicle (n = 9) 1 hour before an infusion of purified E. coli endotoxin was given in a dose of 10 micrograms.kg-1.h-1 over 6 hours. Another 3 pigs also injected with vitamin A, but not endotoxin, served as controls.

RESULTS

Vitamin A- and endotoxin-injected pigs were significantly less affected in several circulatory and respiratory variables as compared to vehicle-and endotoxin-injected animals (e.g., blood pressure; heart rate; cardiac index; pulmonary capillary wedge pressure; left and right ventricular stroke work indices; pH; base excess; oxygen delivery; and oxygen extraction). Vitamin A did not per se significantly affect these variables. Hb increased significantly in the vehicle group, indicating a more pronounced capillary permeability. Urinary output or fluid supply did not differ between the groups. Myocardial production of metabolites of prostacyclin or thromboxane A2 did not differ between the groups.

CONCLUSION

Pre-treatment with vitamin A had a beneficial effect on several variables, such as oxygen delivery and metabolic acidosis in the endotoxaemic pig. Improvement of these variables is associated with increased survival in septic shock and may indicate reduced tissue hypoxia. Thus, vitamin A may turn out to be useful as a prophylactic agent in conditions where septic shock is apt to occur.

Dynamic accumulation of neutrophils in lungs and visceral organs during early abdominal sepsis in the pig

Activation and accumulation of polymorphonuclear leukocytes (PMNs, neutrophils) in the lungs is considered an important mechanism in the pathogenesis of pulmonary dysfunction in association with sepsis. It probably constitutes only part of a general cellular response; and a corresponding reaction has been implicated in other organs during sepsis (e.g., the liver). In this experiment a model was developed that allows study of the dynamic PMN reaction in the lungs and visceral organs during early abdominal sepsis. The animals were divided into two groups. In the septic group (n = 8) a bacterial challenge was attempted through the intraperitoneal administration of Escherichia coli (1 x 10(11)/kg). Five animals served as controls. All animals in the septic group developed bacteremia, leukopenia, and a hypodynamic circulatory response. PMNs were selectively labeled with 111In-oxine. The activity over the organs was followed dynamically with a gamma camera. The animals subjected to peritonitis exhibited a significant increase in 111In-oxine activity (i.e., neutrophil trapping) in the lungs, compared to the controls at 40 minutes and onward during the observation period. A similar picture was seen over the liver and abdomen, with significance after 70 minutes. The findings in this study indicate that accumulation of PMNs is an early phenomenon not only in the lungs but also in the liver during the development of sepsis. The present model offers possibilities for further studies of the cellular reactions during sepsis.

Septic shock in critically ill patients: aetiology, management and outcome

Over a period of 28 months, 45 episodes of septic shock from 83 episodes of bacteraemia were studied prospectively to evaluate their clinical profile, management and outcome. Thirty-six patients were studied, the overall incidence of septic shock being 54.2%. Gram-negative organisms accounted for 23 (51.1%) of such episodes, Gram-positive 17 (37.8%), and three episodes were polymicrobial (6.7%). The organisms isolated most frequently were Staphylococcus epidermidis (17.8%), Pseudomonas aeruginosa (13.3%), Escherichia coli and Klebsiella sp. (each 11.1%). Coagulation abnormalities were detected in 32 episodes (78%) and disseminated intravascular coagulation (DIC) occurred in 11 of these with high mortality. The most common underlying conditions were respiratory, hepatic and renal failures. The majority of these patients received crystalloids, colloids, vasopressor drugs and blood. Swan-Ganz catheters (SGC) were inserted on eight occasions, the majority of times indicating a hyperdynamic circulatory response. The overall mortality was 40%, despite aggressive management and intensive care. The most important factor in reducing mortality is early detection of bacteraemia and prompt management of these patients.

Temporal trends in septicemia in a community hospital

A prior study of septicemia in our community teaching hospital demonstrated the importance of case mix categories in understanding differences in rates of septicemia seen in hospitals. This study provides a 10 year, in 1982, and a 15 year, in 1987, follow-up of septicemia from the same hospital. A substantial increase in the incidence of septicemia was noted in 1982 and 1987. Underlying illness categories continued to be important predictors of incidence of septicemia and fatality rates. The sites of infections, relative mix of community-acquired and nosocomial infections, and mix of organisms were fairly stable throughout the period. The overall incidence of septicemia increased from 34/10,000 admissions in 1970-1973 to 87/10,000 in 1982 and 103/10,000 in 1987. The major explanations for these increases are: (a) a striking increase in the use of blood cultures from 1 blood culture per 10.4 patients in 1973 to 1 blood culture per 3.3 patients in 1987; (b) an increase in the proportion of patients in the Medicare age group from 13% in 1970-1973 to 24% in 1987, with that age group accounting for 33% of the cases of septicemia in 1970-1973 and 55% in 1982 and 1987; and (c) a modest change in the case mix category of ultimately fatal underlying illness and a probable increase in the acuity of illness for most patients admitted. Parallel changes in frequency of use of blood cultures have occurred at the previously evaluated medical school teaching hospital in the same community. These same explanations are likely to be applicable for the same time period in other acute care hospitals as well.

Modern approaches to the therapy of septic shock

Bacteremia from gram-negative rods is a great cause of concern for hospital physicians today. Shock-complicating gram-negative sepsis has a mortality rate of 60% and above, despite early diagnosis and treatment. Intensive research efforts have shown new pathophysiological mechanisms and mediators involved in septic shock, with changes in recommended treatment protocols. In this report, the authors review the use of corticosteroids, fibronectin, naloxone hydrochloride, and immunotherapy, with emphasis on theoretical considerations and relevant clinical experience. Although these treatment methods may have been promising initially, data from large double-blind human trials are either lacking or unencouraging. While continued research and modern therapeutic approaches should improve future survival rates from septic shock, use of the therapies reviewed should be considered experimental at this time.

Pneumonia during pregnancy: has modern technology improved maternal and fetal outcome?

The maternal death rate and rate of preterm delivery associated with pneumonia during pregnancy have not decreased since the introduction of antibiotics four decades ago. We retrospectively reviewed 25 cases of pneumonia during pregnancy; these cases occurred among 32,179 deliveries. Medical complications included: bacteremia, 16%; empyema, 8%; atrial fibrillation, 4%; respiratory failure necessitating mechanical ventilation, 20%. Obstetric complications occurring during the pneumonia episode included: preterm labor, 44%; preterm delivery, 36%. A patient with cystic fibrosis died; one stillbirth and two neonatal deaths occurred. Underlying maternal disease was significantly associated with maternal medical complications (p = 0.023) and preterm delivery (p = 0.012). Significant medical and obstetric complications continue to occur frequently despite modern antimicrobial, tocolytic, and supportive therapy. Underlying maternal disease, including acquired immunodeficiency syndrome and cystic fibrosis, was associated with preterm delivery and neonatal and maternal death.