Pressure transducers: an overlooked source of sepsis in the intensive care unit

Between January 1988 and May 1989 twenty cases of bacteremia due to Flavobacterium sp. occurred in 17 patients admitted to a surgical intensive care unit. Epidemiologic studies disclosed that the source of the Flavobacterium bacteremias was contaminated reusable pressure transducers. Despite the use of disposable domes spread of the bacteria from the contaminated transducer heads to the fluids given to the patients occurred. An indirect contamination by hands at the time the equipment was initially assembled must have been the mode of transmission. Reinstitution of routine disinfection of the transducer heads controlled the outbreak. Disposable domes failed to prevent septicemia from contaminated pressure transducers.

The haemodynamics of septic shock

Both peripheral vascular abnormalities and changes in myocardial function are hallmarks of septic shock. Their complex interactions result in inadequate and maldistributed microcirculatory flow and progressive organ dysfunction. Inappropriate vasodilation, microembolization and endothelial cell injury are proposed mechanisms that may induce maldistribution of flow in the microcirculation and inefficient, defective peripheral oxygen extraction. Abnormal myocardial function is manifested by diminished right and left ventricular ejection fractions, ventricular dilatation, altered Frank-Starling curves and diastolic pressure-volume relationships. These changes are already observed in an early stage of septic shock and are entirely reversible in survivors.

Multi-organ damage in exertional heat stroke

Exertion-induced heat stroke is a relatively rare disorder in the moderate maritime climate of The Netherlands. Serious complications of excessive physical activity rarely occur. We describe a marathon runner with multi-organ failure after exertion-induced heat stroke. The patient developed shock, diarrhoea, coma, rhabdomyolysis, acute renal failure, liver cell damage and disseminated intravascular coagulation but recovered completely.

Effect of dopamine vs norepinephrine on hemodynamics in septic shock. Emphasis on right ventricular performance

The effects of continuously infused dopamine and norepinephrine on hemodynamics, oxygen metabolism, and right ventricular (RV) performance were studied by crossover design in ten patients with septic shock who needed treatment with vasoactive drugs after fluid replacement. Standard hemodynamic measurements were obtained and RV performance assessed before and 1 h after the start of the infusion. All but one patient had pulmonary hypertension, and in seven the RV ejection fraction (RVEF) was lower than 50 percent at baseline. Drugs were titrated to a systolic arterial blood pressure of mean 106 +/- 18 mm Hg for dopamine and 116 +/- 20 mm Hg for norepinephrine (NS). Dopamine infusion increased the cardiac index (CI) 16 percent (p less than 0.02), but heart rate and systemic and pulmonary vascular resistances were unchanged. With norepinephrine CI was unchanged, a heart rate decreased 7 percent (p less than 0.05), and systemic and pulmonary vascular resistance increased 35 and 26 percent, respectively (p less than 0.05). With both drugs, RV volumes and RVEF remained unchanged, and systemic oxygen consumption increased equally (by 19 percent for dopamine and 22 percent for norepinephrine, p less than 0.05); systemic oxygen delivery rose by 17 percent during dopamine infusion and was unchanged during norepinephrine infusion. Norepinephrine increased oxygen extraction vs dopamine (p less than 0.05). There were no differences in urinary output. Norepinephrine may improve the RV oxygen supply/demand ratio, but this potentially beneficial effect on RV ejection fraction may be offset by a concomitant increase in pulmonary vascular resistance and RV afterload. Norepinephrine may not adversely affect the peripheral circulation. In short-term treatment of volume-resuscitated, severe septic shock complicated by pulmonary hypertension and impaired RV performance, norepinephrine may be at least as effective as dopamine.

Biventricular performance during volume loading in patients with early septic shock, with emphasis on the right ventricle: a combined hemodynamic and radionuclide study

The cardiac response to a rapid volume infusion was studied in 18 patients with septic shock accompanied by pulmonary hypertension. Right and left ventricular ejection fractions were measured, and right and left ventricular volume indices were calculated from ejection fractions and stroke volumes before and 30 minutes after the start of the infusion. Responders (13 patients) showed an increase in stroke volume index (SVI) as a result of a mean 30% increase in right ventricular end-diastolic volume index (RVEDVI) and a mean 17% increase in left ventricular end-diastolic volume index (LVEDVI) during volume loading. In the nonresponders (five patients) fluid loading resulted in a decreased or unchanged SVI; this was accompanied by a 7% increase in RVEDVI but no change in LVEDVI, although both the central venous pressure and pulmonary capillary wedge pressure increased. At baseline, nonresponders differed from responders as evidenced by a high central venous pressure and RVEDVI but a lower mean arterial pressure: thus, right ventricular coronary perfusion pressure was lower and right ventricular wall stress may have been higher. Mean pulmonary artery pressure did not differ between the groups. Our data suggest that in some patients with septic shock volume loading does not result in increased forward flow because of right ventricular failure associated with pulmonary hypertension and coronary hypotension.

The influence of catecholamines on right ventricular function in septic shock

Catecholamines play an important role in the treatment of septic shock. Not much is known about their effects on right ventricular function. In this paper the available data on the effects of different catecholamines on right ventricular dysfunction complicating septic shock are reviewed.

The immediate effect of nitroglycerin on total body blood volume distribution in patients with congestive heart failure: a non-invasive study

The effect of sublingually administered nitroglycerin (0.5 mg) on distribution of blood volume in 16 patients with congestive heart failure (NYHA class II and III), randomly assigned to placebo (N = 8) or nitroglycerin (N = 8) was studied 20 minutes after in vivo labelling of red blood cells with 99m-Tc pertechnetate. Count rates over thorax, abdomen and legs were collected with a large field gamma camera and expressed as percentage changes of baseline value. Changes in count rates, averaged for 5, 10 and 15 minutes after drug administration showed a significant decrease in the nitroglycerin group as compared to the placebo group over the thorax (mean 5%, P less than 0.01) and over the liver (mean 5%, P less than 0.05) and a significant increase over the abdomen (mean 4%, P less than 0.01) and the legs (mean 9%, P less than 0.01). After nitroglycerin, the changes in pulmonary activity were variable and did not differ from the placebo group. These results indicate that nitroglycerin causes a redistribution of blood volume in patients with congestive heart failure. An increase in the vascular capacitance in the abdomen and legs may be responsible for a decrease of blood volume of the thorax and the liver in these patients.

Necrotizing enterocolitis: intraluminal biochemistry in human neonates and a rabbit model

The intestinal contents of 17 neonates with necrotizing enterocolitis were analyzed for pH, carbohydrate, protein, and bacteria. The intraluminal pH was less than 5.0 (16/17). Sufficient carbohydrate and bacteria capable of fermenting the carbohydrate to organic acids were found. The intraluminal protein content was greater than 5 g/dl. The variables of acid and protein were then examined in a rabbit intestinal loop model. The hemorrhagic response in individual loops was measured using Cr51 tagged red blood cells such that the microliters of blood per centimeter intestine could be determined. Loops with organic acid and protein had significantly (p less than 0.01) more intramural blood than control loops. Organic acid (possibly generated by bacterial mixed acid fermentation of carbohydrate) in the presence of protein promotes intramural hemorrhage similar to that seen in neonates with necrotizing enterocolitis.

Interaction between bovine casein and V. cholerae enterotoxin in the rabbit ileal loop

Secretory IgA from human breast milk neutralizes cholera enterotoxin in the rabbit ileal loop system. No similar protection by purified bovine milk proteins could be demonstrated; however, one bovine milk protein, casein, had a deleterious effect on intestine exposed to very small quantities of enterotoxin. Highly purified cholera toxin (10 or 100 ng) was incubated with bovine protein solutions for 60 min at 37 degrees C. One-milliliter aliquots were then injected into prepared rabbit intestine loops. The animals were sacrificed at 18 h and the intestinal loop contents were aspirated, and a volume to length of loop ratio (V/L) was determined. The activity of 100 ng of toxin was not enhanced by the majority of bovine milk proteins, but bovine casein caused a 14-40% increase in the fluid production (V/L of casein + toxin versus toxin, 1.05 versus 0.92 and 1.82 versus 1.30). All of the bovine proteins but casein inhibited the action of low dose enterotoxin. Bovine casein caused a 78-90% increase in fluid production by loops exposed to a suboptimal toxin dose (10 ng) (V/L of casein + toxin versus toxin, 1.12 versus 0.63 and 0.95 versus 0.50). Virtually all of this enhancement of enterotoxin fluid response resided in the purified alpha-casein fraction.

Assessment of risk factors and surgical outcome

Patients with known cardiac disease who face operative procedures are usually more concerned than other patients because they perceive themselves to be at greater risk. By reviewing several studies of preoperative risk factors, the author attempts to find which factors imply significant risk of mortality in surgical patients with cardiac disease.

Spontaneous rupture of the spleen complicating portal hypertension

A 54-year-old male with alcoholic liver cirrhosis and hepatic coma grade IV is described, who succumbed as a result of spontaneous rupture of the spleen. A relationship to portal hypertension is suggested, although haemorrhagic diathesis and sepsis may have been contributing factors.

Starting insulin therapy in children with newly diagnosed diabetes

Eight years ago, a decision was made to eliminate unnecessary hospitalization of children with newly diagnosed diabetes mellitus. This decision required changes in the basic approach to starting insulin therapy and education of the parents. Since then, 52 children aged 11 months to 16 years have been treated. Forty-four of these children were sent home after one to four hours of instruction. Five children received intravenous therapy for two to five hours and then went home. The remaining three children were admitted to the hospital for 18 to 40 hours. Subsequent establishment, at home, of diabetes control was accomplished without incident. The first injection of subcutaneous insulin was generally a combination of regular and slowly absorbed insulin. This approach has been well received by patients, parents, and referring physicians.

Newborn phenylalanine/tyrosine metabolism. Implications for screening for phenylketonuria

Controversy over the sensitivity of newborn screening for phenylketonuria (PKU) has recently led to the specific recommendation that infants discharged within the first 24 hours of life be routinely retested at 1 to 2 weeks of age. To address this controversy, data from cord blood samples, phenylalanine (Phe) tolerance tests at 3 days of age, and sequential plasma Phe determinations in six siblings of known cases of PKU or hyperphenylalaninemia were analyzed, along with data from the literature. These analyses showed that normal and probably heterozygous infants decrease their Phe concentrations with age, while infants with PKU or PKU variants increase their Phe concentrations with age but at varying rates. Predictive equations showed that the sensitivity of the screening test rapidly increases with age, so that the usual critical value of 4 mg/dL is satisfactory for suspecting PKU after 18 hours of age. A critical value of 3 mg/dL would be equally satisfactory at any age, if the Guthrie test were appropriately modified to include a 3-mg/dL standard.

Transfusion nomogram: an application of physiology to clinical decisions regarding the use of blood

A nomogram has been prepared that depicts relationships between cardiac output (Q), oxygen consumption (Vo2), hemoglobin concentration (Hb), the position of the oxygen-hemoglobin dissociation curve, the oxygen saturation of arterial blood (SaO2), and the partial pressure of oxygen in the mixed venous blood (PVO2). Examples are provided to illustrate how this nomogram may be employed to facilitate decisions regarding the need for blood transfusions in patients in whom oxygen delivery may be impaired.