Nutrition support is not beneficial and can be harmful in critically ill patients.

The introductory remark by Lucretius serves as a reminder that nutrient intake can have very different consequences in different subjects. In the patient with an acute or serious illness, metabolic derangements can transform a substance that is normally a source of energy into a source of metabolic toxins. The potential for organic nutrients to become organic toxins in the diseased host is a phenomenon that deserves more attention in the debate about the value of nutrition support in critically ill patients.

Trendelenburg position and oxygen transport in hypovolemic adults.

STUDY OBJECTIVE: To evaluate the effect of the Trendelenburg position on oxygen transport in hypovolemic patients. DESIGN: A prospective, self-controlled sequential design. INTERVENTIONS: All patients had indwelling pulmonary artery catheters, and hypovolemia was confirmed by a pulmonary artery wedge pressure of 6 mm Hg or less. Hemodynamic and oxygen transport variables were measured with the patient supine and again ten minutes after placing the patient in the Trendelenburg position. SETTING: University-affiliated tertiary care surgical ICU. TYPE OF PARTICIPANTS: Eight postoperative adults. RESULTS: Mean arterial blood pressure increased from 64.9 +/- 4.9 to 75.6 +/- 3.5 mm Hg (P < .05), pulmonary artery wedge pressure increased from 4.6 +/- 1.1 to 7.9 +/- 0.8 mm Hg (P < .05), and the systemic vascular resistance rose to 2,965 +/- 210 from 2,302 +/- 199 dyne.sec/cm5 (P < .05). There was no significant change in cardiac index, oxygen delivery, oxygen consumption, or oxygen extraction ratio. CONCLUSION: The increase in blood pressure from Trendelenburg position is not associated with an improvement in blood flow or tissue oxygenation.

Neuroleptic malignant syndrome in the intensive care unit.

The authors describe the postoperative course of a 43-year-old man. Haloperidol was administered for agitation while the patient was in the intensive care unit. After administration of this drug, neuroleptic malignant syndrome developed. The authors review the literature as it relates to the use of haloperidol and the associated adverse effect of neuroleptic malignant syndrome. This report of a case demonstrating haloperidol's potential toxicity is intended to increase awareness within the critical care community and thereby prompt early diagnosis and aggressive management to prevent haloperidol-associated morbidity and mortality.

A new perspective on stress ulcer prophylaxis.

Gastric acid suppression by use of either antacids or histamine H2-receptor antagonist therapy is the mainstay of stress ulcer prophylaxis. Available evidence indicating an antimicrobial role for gastric acid calls for the reevaluation of gastric acid suppression. A pH of greater than 4.0 leads to bacterial overgrowth and colonization of the upper gastrointestinal tract which has been associated with nosocomial pneumonia, bacterial translocation from the gut, systemic sepsis, and multiple-organ failure. The availability of alternative therapy should discourage the routine use of acid-suppression therapy in the critically ill patient.

Tube feeding-related diarrhea in acutely Ill patients.

Acutely ill patients received tube feeding for an average of 15.8 days and, on average, 35% of those days were spent in the intensive care unit (ICU). Patients were prospectively assigned either a fiber-free formula (FFF-OSMOLITE HN, Ross; n = 50) or a fiber-supplemented (soy polysaccharide 14.4 g/L) formula (FSF = JEVITY, Ross; n = 50). Diarrhea was defined as three or more loose or watery stools per day and occurred in 30% of all patients. Diarrhea developed in 29 (41%) of the 71 patients who received antibiotics during, or within 2 weeks prior to, the feeding period, whereas only 1 (3%) of the 29 patients not receiving antibiotics developed diarrhea (p less than 0.005); and this patient developed diarrhea on the day of death. Among the 30 patients with diarrhea, stool Clostridium difficile (CD) toxin was positive in 15 (50%), negative in 11 (37%), and was not measured in four. The mean serum albumin was significantly lower in patients with diarrhea (2.43) than in those without diarrhea (2.75) (p = 0.043). There were no significant differences in age, sex, diagnoses, number of feeding days, and percent ICU days between patients with and without diarrhea. While not statistically significant, patients who received FSF were observed to have a lower incidence of diarrhea, a lower percentage of diarrhea days per total feeding days, and a lower frequency of positive CD toxin assays than patients who received FFF. In this patient population, antibiotic usage was the factor most strongly associated with diarrhea during tube feedings.

Improved use of arterial blood gas analysis in suspected pulmonary embolism.

Since hypoxemia is not known to be a sensitive indicator of acute pulmonary embolism, we performed a retrospective study to determine whether an increased P(A-a)O2 gradient or hypocapnia improved the sensitivity of blood gas analysis in acute embolism. The study group consisted of 78 patients with angiographically documented emboli who had blood gas samples obtained while breathing room air. None had a prior history of cardiopulmonary disease. Hypoxemia was present in 59 patients (76 percent), hypoxemia or hypocapnia in 73 patients (93 percent), an increased P(A-a)O2 gradient in 74 patients (95 percent), and an increased P(A-a)O2 gradient or hypocapnia in 77 patients (98 percent). Only one patient with acute embolism showed a normal P(A-a)O2 gradient and normal PaCO2 breathing room air. These results suggest that a normal P(A-a)O2 gradient and a normal PaCO2 obtained in a patient during room air breathing can be used as evidence against the presence of pulmonary emboli.

Altered therapy of suspected pulmonary embolism using leg venography.

The traditional approach to the diagnosis of pulmonary embolism involves attempts to document the embolus in the lungs. An alternative diagnostic approach is to document the source of the embolus in the iliofemoral venous system. The present case shows how a search for leg thrombosis in suspected pulmonary embolism can also have an impact in choosing the optimal therapy to prevent recurrent embolization.

Unusual case of enlarging pulmonary mass.

Rounded atelectasis is an uncommon form of pulmonary collapse that presents as an asymptomatic lung mass, and thus, can appear very similar to a pulmonary neoplasm. One feature that has been used to differentiate rounded atelectasis from a pulmonary malignancy is the lack of growth observed in cases of rounded atelectasis. The case presented here demonstrates that it is possible for rounded atelectasis to increase in size. This is the first documented case of enlargement of rounded atelectasis and shows that this disorder should be added to the list of benign causes of an enlarging pulmonary mass.

Bacteremic pneumococcal pneumonia and myoglobinuric renal failure.

A case of bacteremic pneumococcal pneumonia associated with rhabdomyolysis and myoglobinuric renal failure is presented. This may be the first report of the association of these two disorders, and may influence the choice of antibiotic selection in patients with rhabdomyolysis and a pulmonary infiltrate.

The effect of aspirin on protein breakdown in septic man.

In pathological states associated with hypermetabolism, such as acute sepsis, there is marked negative N balance. It has been suggested that the pathway for this response is via leukocyte pyrogen (interleukin I) acting on cyclooxygenase to stimulate prostaglandin release, which then stimulates proteolysis via the lysosomal pathway. In vitro, cyclooxygenase inhibitors decrease proteolysis in muscle tissue from septic rats. We tested this hypothesis in vivo in severely septic patients by using aspirin as the test cyclooxygenase inhibitor. Septic patients (n = 4) were given a primed, constant infusion (183 mg prime, then 37 mg/hr) of 15N-labeled urea for 6 hr to obtain a blood [15N]urea plateau. Blood samples were taken every 30 min. At 180 min 1500 mg of aspirin was given po. If aspirin inhibited protein breakdown, the plateau level should rise, since less cold urea derived from protein breakdown will enter the urea pool. Aspirin did not cause any change in either the BUN concentration, its 15N enrichment, or any of the plasma amino acids. In conclusion, cyclooxygenase inhibition by aspirin in vivo does not decrease protein breakdown in hypercatabolic septic patients.

Diaphragmatic strength during weaning from mechanical ventilation.

Respiratory muscle weakness is considered to be a factor in the inability to wean from mechanical ventilation. To assess this possibility, the present study examined the mechanical behavior of the diaphragm by measuring the change in transdiaphragmatic pressure (delta Pdi) during weaning. Nine "T-piece" weanings were carried out in seven patients with prior weaning failure and were terminated with the development of hypercapnia, hypoxemia, or severe tachypnea. Serial measurements of delta Pdi during these weans revealed that (1) in no case was there a decrease in delta Pdi at termination of weaning, and (2) in the subgroup of patients whose weaning failed because of hypercapnia, the increase in arterial carbon dioxide tension (mean increase of 12 mm Hg) was associated with a significant increase in delta Pdi, from the beginning (21.1 +/- 12.1 cm H2O) to the end (24.8 +/- 13.4 cm H2O) of the trial (p less than 0.05). We conclude that failure to wean in these patients, in particular the development of carbon dioxide retention, was not due to failure of the diaphragm as a pressure generator.

An analytical approach to creation of parenteral feeding solutions: implementation on a microcomputer.

The creation of a parenteral feeding regimen can be described in mathematical terms by a system of algebraic equations. An example of such a system having clinical applicability is discussed in detail. Since the system is too cumbersome for use by hand or calculator, a microcomputer program incorporating the system was developed, and is also discussed.

An interpretive computer program for analyzing hemodynamic problems in the ICU.

A computer program is described that can generate and interpret hemodynamic profiles, and suggest a therapeutic approach to the identified hemodynamic problem. This program represents the first attempt to develop interpretive software for hemodynamic problems encountered in the ICU.

The use of a pocket computer for hemodynamic profiles.

The pocket computer system for generating hemodynamic profiles is described. This system provides advantages over systems presently used to generate hemodynamic profiles because it is easy to program, simple to use, and is relatively inexpensive.