Neurogenic control of renal function in response to graded nonhypotensive hemorrhage in conscious dogs

The reflex control of plasma renin activity (PRA) and urinary sodium excretion (UNaV) was evaluated in 13 dogs instrumented for chronic study and maintained on a normal sodium intake (40 meq/day). Graded blood volume depletion of 14 (BVD1) and 21% (BVD2) of the estimated total blood volume was used to activate renal sympathetic nerve activity (RSNA), and experiments were conducted before and after bilateral renal denervation (DNX). In dogs with innervated kidneys, nonhypotensive BVD1 increased RSNA 40.9 +/- 10.9% (P < 0.05) above control. Blood volume depletion increased PRA from 1.95 +/- 0.52 to 3.5 +/- 0.57 ng.ml-1 x h-1 and decreased UNaV from 58.2 +/- 10.1 to 35.5 +/- 4.3 mu eq/min without changing renal blood flow or glomerular filtration rate. BVD2 failed to further activate RSNA (52.0 +/- 16.7%) but did increase PRA to 4.85 +/- 0.83 ng.ml-1 x h-1 and decreased UNaV to 17.9 +/- 2.7 mu eq/min. Renal DNX (n = 13) abolished both the PRA and antinatriuretic responses to BVD1 and BVD2. Thus volume-invoked reflex activation of RSNA, but not altered renal hemodynamics, mediates, activation of PRA and antinatriuresis. This neurogenic control of renal function may be critical to the rapid regulation of extracellular fluid volume, via alterations in urinary excretion.

Re-examining handedness in schizophrenia: now you see it--now you don't

The present study was designed to examine patterns of handedness across tasks (i.e., those requiring less vs. greater skill) and over time (initially and 1 month later) in 72 schizophrenic patients and 105 normal controls. Two important methodologic advances were introduced: (1) two handedness tasks, varying in skill level (simple vs. complex); and (2) the addition of a retest on both tasks, 1 month later. Results show a higher incidence (43%) of mixed handedness in the schizophrenic sample than in normal controls (14.3%) on tasks requiring less precision in performance. Similar results were obtained when schizophrenic patients were retested 1 month later, RI = .88. When the more demanding set of tasks was presented, the frequency of mixed handed schizophrenics dropped by 50% at initial testing. Despite these findings, there was no evidence for stability of change over time. For example, each of the most extreme shifters at Time 1 was fully lateralized 1 month later.

High-level positive end-expiratory pressure management in trauma-associated adult respiratory distress syndrome

This study evaluated the effect of high-level positive end-expiratory pressure (PEEP) on mortality, barotrauma, intrapulmonary shunt (Qsp/Qt), and oxygen delivery (DO2) in posttraumatic adult respiratory distress syndrome (ARDS). All hypoxemic trauma patients admitted to the surgical intensive care unit (SICU) in 1989-1990 who received PEEP greater than 15 cm H2O were included. The PEEP was titrated to achieve an intrapulmonary shunt (Qsp/Qt) of approximately 0.20, and FIO2 was weaned to less than 0.50. Hemodynamic and pulmonary variables at four distinct intervals were recorded. Fifty-nine patients received PEEP greater than 15 cm H2O. Of these, 19 patients died of severe head injury or uncontrollable hemorrhage (16 within 48 hours). Forty (29 male, 11 female) were evaluated in detail. The PEEP levels ranged from 18-50 cm H2O with a mean of 27. PaO2/FIO2 ratios and Qsp/Qt improved as PEEP therapy was titrated. Cardiac index and oxygen delivery were maintained or improved throughout PEEP therapy by transfusion and fluid resuscitation, with a mean maximum positive fluid balance of 21.1 L and an average of 51 units of blood and blood products transfused per patients during their SICU stay. Twenty-nine (73%) had evidence of barotrauma, the majority being pneumothoraces clearly related to the initial trauma. Only three (7.5%) had evidence of barotrauma not related to trauma or line insertion. Eight of 40 patients (20%) died. Mean ISS and RTS for the entire group were 32 and 5.88, respectively. We conclude that titration of PEEP to achieve a Qsp/Qt of approximately 0.20 is an attainable goal. This was accomplished with minimal hemodynamic effects or barotrauma and a low mortality rate.

Antibody response of calves to immunoaffinity-purified bovine respiratory syncytial virus VP70 after vaccination and challenge exposure

Immunoaffinity-purified bovine respiratory syncytial virus (BRSV) fusion (F) protein elicited anti-BRSV-specific antibody responses in BRSV-seronegative calves. After primary vaccination, all calves seroconverted to BRSV as determined by the virus neutralization (VN) test and developed anti-F protein antibodies detectable by protein immunoblot analyses. Subsequent vaccinations induced greater than twofold increase in VN titer in 3 of 9 (33%) calves, and 1 calf became VN-negative, but still had nonneutralizing antibody detectable by protein immunoblot analysis. This calf remained seronegative after challenge exposure. Two groups of calves were vaccinated IM with immunoaffinity-purified BRSV F protein. Each dose was 2 ml containing 20 micrograms of purified F protein. Freund's adjuvants were used for all vaccinations, with Freund's complete adjuvant used for the primary vaccination and Freund's incomplete adjuvant for subsequent vaccinations. The vaccine was administered to both groups at weeks 0 and 3; the first group received a third vaccination at weeks 21. Group-1 and -2 vaccinated calves and non-vaccinated contact controls were intranasally aerosol challenge-exposed with low cell culture-passage BRSV on weeks 22 and 9, respectively. Eight of 9 vaccinated calves did not develop a humoral anamnestic response following challenge exposure, as demonstrated by VN test and protein immunoblot analyses. Calf 14 from group 1 which had a 1:2 VN antibody titer prior to vaccination, was the only calf that developed an anamnestic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetic therapy in critically ill trauma patients

OBJECTIVES

To compare the incidence of pulmonary complications and hospital resource utilisation in patients treated with continuous rotation therapy versus manual turning in a traditional hospital bed.

DESIGN

Prospective, randomised clinical trial.

SETTING

Surgical intensive care unit of a large, tertiary care, urban hospital.

PATIENTS

One-hundred-and-thirty-seven consecutive injured patients admitted to the Surgical Intensive Care Unit were prospectively randomised to receive either the Rotorest Kinetic Treatment Table or a traditional hospital bed. One hundred of these patients met the study criteria and are the basis of this report.

METHODS

The patients' medical records were reviewed in a prospective manner to determine the frequency and severity of pulmonary complications and resource utilisation in the two patient groups.

MAIN RESULTS

There were no significant differences in the minimum, average, or maximum pO 2, pCO 2, PEEP, IMV rate, or pre-extubation blood gases during the first seven days of the study. Fewer cardiac output measurements, arterial blood gas measurements, chest X-rays, respiratory therapies, hours intubated, days in the ICU, days in the step-down unit, days in the hospital, and lower ICU charges, respiratory care charges, and total hospital charges were utilised in the patients treated with the kinetic bed. The incidence of pulmonary event complications and process complications was lower in the group of patients treated on the Rotorest bed.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Hydroxydesipramine and desipramine plasma levels and electrocardiographic effects in depressed younger adults

Desipramine was given to 34 outpatients aged 20 to 51 years who had primary major depressive disorder but who were otherwise in good health. Daily dosage at bedtime was constant for the final 3 weeks of the 5-week study (mean, [SD] 169.1 [46.1] mg). Electrocardiograms done predrug and after 5 weeks were read by a cardiologist blind to the order in which they were performed. Plasma samples drawn 14 hours after the final study dose were assayed by high performance liquid chromatography; mean (SD) levels were 140.2 (140.0) ng/ml for desipramine and 56.5 (29.4) ng/ml for 2-hydroxydesipramine (2-OH-DMI). Heart rate and PR, QRS and QTc intervals were significantly greater at the end of the study than at baseline, while QT intervals were significantly less. Changes in heart rate and PR, QT and QTc intervals were significantly negatively correlated with the value of the respective cardiac parameters at baseline. Changes in PR interval were significantly positively correlated with log desipramine, log 2-OH-DMI and log (desipramine + 2-OH-DMI). Stepwise multiple regression analyses showed that, for PR interval, each of the three plasma level variables showed a significant ability to improve R2 over that obtained from baseline PR alone. These findings suggest that both 2-OH-DMI and desipramine plasma levels predict a prolongation of intracardiac conduction in younger adults and that monitoring both levels may be useful in the clinical management of certain younger adult patients.

Use of recombinant human erythropoietin (r-HuEPO) in a Jehovah's Witness refusing transfusion of blood products: case report

Recombinant human erythropoietin (r-HuEPO) administration to a Jehovah's witness refusing blood transfusions increased her nadir packed cell volume from 13% to 37% and reticulocyte count from 2% to 17.7%. R-HuEPO may provide an alternative safe and effective therapy in life-threatening anemia when blood transfusions are unacceptable to the patient.

Errors in estimating energy expenditure in critically ill surgical patients

Thirty-one critically ill surgical patients were receiving central parenteral nutrition. All were intubated, and 29 were receiving mechanical ventilatory support. Nutritional and metabolic data were recorded at the time of indirect calorimetry. Measured energy expenditure (MEE) was compared with predictions of basal energy expenditure (BEE) and calculated energy expenditure, defined as the product of BEE and a stress factor estimated by the nutrition support service to account for severity of illness and activity. The MEE was significantly greater than the BEE and significantly less than the calculated energy expenditure. The estimated stress factor was significantly greater than the actual MEE/BEE ratio, and the correlation between these values was poor. Clinical assessment may overestimate energy expenditure in critically ill patients because of the apparent degree of illness used to determine the stress factor. Bedside indirect calorimetry may be useful to assess more accurately energy expenditure and optimize nutritional support.

Physiologic effects of steep positioning in the surgical intensive care unit

Ten hemodynamically stable patients requiring mechanical ventilation for radiographically symmetric acute lung disease were studied during steep lateral positioning and continuous rotation in a Roto Rest kinetic treatment bed. There were no significant hemodynamic or ventilatory differences among the four positions (supine, right side down, left side down, and rotating). In four patients, arterial oxygen pressure (PaO2) decreased 16% to 49% in the lateral position when compared with the supine position. Continuous rotation restored the PaO2 toward the supine value in each patient. In six patients, PaO2 increased 11% to 35% during lateral positioning. In five of the six patients, the increase in PaO2 differed between sides, suggesting asymmetric lung disease. Continuous rotation did not significantly alter the PaO2 from the supine values in these patients. Adverse effects on oxygenation caused by positional changes may be reversed by continuous rotation using the Roto Rest kinetic bed.

Clinical validation of a new metabolic monitor suitable for use in critically ill patients

This report documents the validity of clinical measurements of oxygen consumption (VO2) and carbon dioxide production (VCO2) made with a new metabolic gas monitor (MGM) suitable for use in critically ill patients receiving mechanical ventilatory support. Paired samples of inspired and expired gases were obtained, and exhaled minute volume was measured in 12 patients receiving supplemental oxygen, intermittent mandatory ventilation, and PEEP. Gas volume was measured with a calibrated spirometer and oxygen and CO2 fractions were measured by mass spectrometry. Measured and derived values were compared to those obtained from the MGM connected in series with the ventilator circuit. There were no statistically significant differences between values obtained from the mass spectrometer/spirometer vs. the MGM in exhaled volume (8.60 +/- 3.81 vs. 8.58 +/- 3.72 [SD] L/min), fraction of inspired oxygen (0.451 +/- 0.011 vs. 0.452 +/- 0.010), fraction of expired oxygen (0.413 +/- 0.013 vs. 0.415 +/- 0.012), VO2 (290 +/- 113 vs. 275 +/- 88 ml/min), VCO2 (245 +/- 95 vs. 247 +/- 96 ml/min), or respiratory quotient (0.85 +/- 0.14 vs. 0.88 +/- 0.08). The fraction of expired CO2 measured by the MGM was significantly greater (0.034 +/- 0.006 vs. 0.035 +/- 0.006; p less than .001) than that measured by mass spectrometer/spirometer. Twelve additional patients were studied to compare metabolic measurements made on 45% oxygen with those made at other fraction of inspired oxygen values. There was no significant difference between values measured on 45% oxygen and those measured on 30% to 50% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Titrating positive end-expiratory pressure therapy in patients with early, moderate arterial hypoxemia

A prospective randomized study to compare two physiologic end-points for titrating positive end-expiratory pressure (PEEP) was performed in patients with early, moderate arterial hypoxemia after surgery or trauma. All patients initially received 5 cm H2O of PEEP. In group 1 patients, PEEP was increased only if PaO2 decreased below 65 torr on an inspired oxygen fraction (FIO2) of 0.45. PEEP was then added in 2- to 3-cm H2O increments until PaO2 again was above 65 torr. Group 2 patients were treated with incremental PEEP until the PaO2/FIO2 ratio was greater than 300 or physiologic shunt (Qsp/Qt) was less than 0.20. All therapy other than PEEP was similar in the two groups. There were no statistically significant differences in entry PaO2 (mean 85 +/- 11 [SD] and 87 +/- 11 torr in groups 1 and 2, respectively), and Qsp/Qt was 0.22 in each group. Five (28%) of 18 patients in group 1 and 19 (95%) of 20 patients in group 2 received more than 5 cm H2O of PEEP. Between groups 1 and 2 there were no statistically significant differences in days intubated (3.4 +/- 3 vs. 5.3 +/- 5, respectively), ICU days (5.3 +/- 3 vs. 6.6 +/- 5), hospitalization days (26 +/- 24 vs. 28 +/- 24), incidence of pulmonary barotrauma (0/18 vs. 1/20), ICU mortality (22% vs. 20%), or overall mortality (33% vs. 25%). The number of blood gas analyses and cardiac output measurements, and the total hospital charges were also similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of microbial colonization in open versus closed delivery systems for thermodilution injectate

The incidence of microbial colonization of injectate was studied in open and closed delivery systems used for thermodilution measurement of cardiac output. Patients with pulmonary artery catheters were prospectively randomized to receive either open two-bottle systems or closed systems. Paired cultures of injectate solution were withdrawn through the stopcock at the time of the initial set-up and every 12 h for 48 h. Injectate from eight (35%) of 23 patients with the open system and one (5%) of 20 patients with the closed system yielded a positive culture (p less than .05). Thirteen (10%) of 129 pairs of cultures were positive from the open system, compared to one (0.9%) of 111 pairs from the closed system (p less than .01). There was no statistically significant difference in the number of cardiac output injections between the two groups, but patients having more than the mean number of injections for cardiac output measurement had a significantly (p less than .05) greater likelihood of positive injectate cultures.

Continuous venous oximetry in surgical patients

A prospective study was performed to evaluate the efficacy of continuous venous oximetry to supplement traditional hemodynamic monitoring in 39 critically ill surgical patients. There was no statistically significant difference in SvO2 between the continuous in vivo values and in vitro values (0.694 +/- 0.095 vs. 0.698 +/- 0.108). There was no statistically significant correlation between continuously measured SvO2 and PaO2 (r = 0.09, p greater than 0.5), SaO2 (r = 0.08, p greater than 0.5), or oxygen consumption (r = 0.46, p greater than 0.5). There was a slight but statistically significant correlation between continuously measured SvO2 and cardiac output (r = 0.40, p less than 0.025) and oxygen delivery (r = 0.49, p less than 0.005). There was a highly significant correlation between continuously measured SvO2 and oxygen utilization coefficient (r = -0.96, p less than 0.001). Continuously measured SvO2 is a reliable predictor of SvO2 measured intermittently by in vitro methods. In critically ill surgical patients, SvO2 does not correlate highly with the individual determinants of oxygen transport but rather correlates with the oxygen utilization coefficient and therefore reflects the overall balance between oxygen consumption and delivery.

Continuous monitoring of mixed venous oxygen saturation during aortofemoral bypass grafting

Measurement of mixed venous oxygen saturation (SvO2) may be helpful in the care of critically ill patients. Serial determinations of SvO2 give an index of the relationship between oxygen delivery and tissue oxygen consumption. Continuous monitoring of SvO2 is now readily available with the Shaw Oximetrix pulmonary artery catheter (Oximetrix Inc., Mountain View, CA). This system has provided useful information in the high risk cardiac surgery patient. Continuous monitoring of mixed venous saturation may be helpful in high risk or critically ill general and peripheral vascular surgery patients both in the intensive care unit and in the operating room. The following clinical report is presented to illustrate the usefulness of continuous SvO2 monitoring in a high risk vascular surgery patient.

Patient selection for iced versus room temperature injectate for thermodilution cardiac output determinations

In 42 patients who required hemodynamic monitoring there was no statistically significant difference between mean cardiac output determined with iced vs. room temperature injectate. There was also no statistical difference in mean cardiac output values using iced vs. room temperature injectate when data were grouped according to body temperature, mean arterial pressure, and cardiac output. These results suggest that when cardiac output is measured by the methods described, the use of iced injectate is unnecessary in many critically ill patients.

Enzyme-linked immunosorbent assay for detection of transmissible gastroenteritis virus antibody in swine sera

An enzyme-linked immunosorbent assay (ELISA) was developed for detection and quantification of serum antibodies to transmissible gastroenteritis virus (TGEV) in swine. Sera from pigs inoculated with cell culture-origin TGEV or gut-origin TGEV were tested for anti-TGEV antibody by ELISA and by serum virus-neutralization test (NT). The ELISA detected antibody 3 days (av) sooner than did the NT when sera from pigs inoculated with cell culture-origin TGEV were tested and 1 day sooner than did the NT when sera from pigs inoculated with gut-origin TGEV were tested. The ELISA appeared to be more sensitive than the NT, since ELISA was more responsive to low-level antibody and ELISA titers exceeded NT titers.

Oxygen consumption and optimum PEEP in acute respiratory failure

The effect of PEEP on oxygen consumption (VO2) was observed in 3 groups of dogs. In addition to intermittent and indirect measurements using the expired gas collection and Fick methods, VO2 was measured continuously and directly using the "oxiconsumeter", a device utilizing a relatively simple feedback controlled gas replenishment technique which adapts to standard ventilator circuits. One group of dogs served as controls, while the other 2 groups developed acute respiratory failure (ARF) subsequent to an acute pulmonary injury (API) induced by iv administration of oleic acid. In animals without API, there were no PEEP-induced changes in gas exchange variables; whereas the 2 API groups showed graded improvement in arterial oxygen tension (PaO2), shunt fraction (Qsp/Qt), and alveolar-arterial oxygen tension gradient [P(A-a)O2] during mechanical ventilation with PEEP. In the absence of vascular volume loading, increasing PEEP was associated with decreased cardiac output in dogs with or without API. In contrast, when concurrently fluid resuscitated, the dogs receiving the most severe API showed all of the classic signs of progressive ARF but did not evidence decreased cardiac output with increasing PEEP. VO2 decreased at high PEEP when oxygen transport decreased. The following conclusions were reached: The oxiconsumeter provides a safe cost-effective means for VO2 monitoring, whose convenience and rapidity exceed those of expired gas collections and whose accuracy and reliability far exceeds those of Fick determinations. In general, PEEP has little effect on VO2 provided cardiac output is adequate; in particular, VO2 cannot be used to optimize PEEP via correlation with lung compliance or intrapulmonary shunt fraction. Decreased VO2 during PEEP therapy reflects a significant decrease in cardiac output, and is indication to support cardiac output, or reduce PEEP, or both.