A comparison between a conventional and a fiberoptic flow-directed thermal dilution pulmonary artery catheter in critically ill patients.

Invasive hemodynamic monitoring is frequently required in the management of patients in intensive care units. A fiberoptic flow-directed thermal dilution pulmonary artery catheter capable of continuously monitoring the mixed venous saturation, while more expensive than a conventional pulmonary artery catheter, theoretically could result in better patient care, and might be cost-effective if it resulted either in fewer blood tests being ordered or in less time in the intensive care unit. To test this hypothesis, we designed a randomized trial in our Medical Intensive Care Unit to compare a standard pulmonary artery catheter with a fiberoptic catheter. Twenty-six patients received a standard catheter and 25 patients received the fiberoptic catheter. There were no statistical differences between the groups in age, time in the intensive care unit, number of tests ordered, hours of mechanical ventilator therapy, hours of vasoactive drug therapy, or mortality rate. The only statistically significant differences between the groups were that (1) the fiberoptic catheter required a longer insertion time and (2) there were more technical problems in consistently obtaining the wedge pressure in the patients with the fiberoptic catheters. We conclude that routine substitution of a fiberoptic catheter for the standard pulmonary artery catheter is not indicated.

Microprocessor exercise physiology systems vs a nonautomated system. A comparison of data output.

Several microprocessor exercise physiology systems have been introduced recently. Comparison of the data output between these systems and more traditional nonautomated systems has not been reported extensively. Twelve normal adult men were exercised in random sequence on different days on a Sensormedics MMC Horizon system, the Medical Graphics Corporation System 2000, and a nonautomated system. heart rate, minute ventilation, tidal volume, respiratory frequency, oxygen consumption, and carbon dioxide production were compared at each level of work during a maximal incremental test and during a constant work load test. The overall data output between the three systems was comparable. However, minute ventilation was consistently higher on the Medical Graphics system, oxygen consumption was consistently lower on the Horizon system, and a technical error was discovered in the Medical Graphics system which resulted in a systematic overestimation of carbon dioxide production. Different methods of analyzing the data from the same test (60-s average, 15-s average, breath-by-breath, and 8-breath average) resulted in differences of up to 20 percent in the maximal values. This was greater than the differences between the three systems. Despite the comparability of the data output, important differences did exist which can be potentially significant when data output from one system are compared to predicted normal values obtained under different conditions.

Exercise responses during incremental and high intensity and low intensity steady state exercise in patients with obstructive lung disease and normal control subjects.

A study was undertaken to compare the cardiac and ventilatory responses to different types of exercise between 12 patients with COPD and ten normal age-matched control subjects. Both groups attained comparable heart rates and the percentage of their maximum predicted heart rate. Patients had a higher heart rate and VE with a lower O2P at every level of work load. Patients had a mean VT which approximated their FEV1 and increased their VE predominantly by increasing their respiratory frequency. During the low intensity test, despite the differences in work load, the patients had comparable heart rates and VE. No resting spirometric value accurately predicted work load, VE, or maximal VO2. We conclude that patients have a reduced work tolerance that is not adequately explained by their reduced lung function. Thus, cardiac factors, deconditioning, and the dyspneic sensation may be determinants of exercise limitation in some patients.

Transbronchial biopsy without fluoroscopy. A seven-year perspective.

The use of fluoroscopic guidance for transbronchial biopsy (TBB) during flexible fiberoptic bronchoscopic examination has been controversial. Patient records and bronchoscopy reports for 112 transbronchial biopsies performed with fluoroscopy over a seven-year period were reviewed and compared with those of 135 transbronchial biopsies performed without fluoroscopy over the same interval. Complication rates with regard to pneumothorax, fever, and hemorrhage were compared, as were yield data for neoplasm, sarcoidosis, and other miscellaneous pulmonary diagnoses. Complication rates were low in both groups and not statistically different; yield data were likewise comparable, particularly in diffuse neoplasm and sarcoidosis. This report suggests that TBB without fluoroscopy (in the basilar segments) is safe and that diagnostic yield, particularly in sarcoidosis and diffuse neoplasm, is good.

Tuberculosis. Cause of death in antibiotic era.

A five-year review (1979 to 1983) of 41 patients with active tuberculosis at the time of death was performed to determine the cause of death. Twenty deaths (49 percent) were directly attributed to tuberculosis. Overwhelming tuberculous disease was the cause of death for seven patients, and among them the majority had strikingly low serum levels of albumin. Ten patients died of either massive hemoptysis or respiratory failure. Only two patients died due to progressive drug-resistant disease in an area where drug resistance is common. The majority of patients (21/41; 51 percent) died of common medical problems unrelated to tuberculosis. Eleven patients died from cardiopulmonary disease (five pulmonary emboli, one respiratory failure due to chronic obstructive pulmonary disease, two acute myocardial infarctions, and two primary dysrhythmias). Three deaths were the result of gastrointestinal bleeding, and three patients died as a result of bacterial superinfection. Our data indicate that patients still die of tuberculosis in the era of effective antituberculosis therapy. It is imperative that clinicians are aware that pulmonary emboli, arteriosclerotic heart disease, bacterial superinfection, and gastrointestinal bleeding cause approximately 50 percent of the deaths among patients who have tuberculosis and that prompt recognition and treatment of those diseases might decrease the mortality from tuberculosis.

Major life events as risk factors for post-stroke depression.

Depression is a significant sequela of stroke which contributes to increased morbidity and mortality in stroke survivors. Psychosocial stressors, such as major life events, pose risk factors for developing depression in non-stroke populations. This study evaluated major life events as a risk factor for developing post-stroke depression (PSD) during the first year post-stroke. One hundred and eleven patients who completed the Center for Epidemiological Studies-Depression Scale at four time periods during the first year post-stroke were assessed for PSD and asked if they had experienced a major life event in the prior 6 months (other than the stroke). The subjects completed the evaluations acutely (7-10 days), and at 3, 6, and 12 months post-stroke. At 6 months post-stroke patients were significantly more likely to be depressed if they had a major life event in the prior 6 months (other than the stroke) than if they had not, chi 2 (df = 1) = 4.83, p < 0.028, relative risk = 2.31, 95% confidence interval 1.15-4.62. Life events pose significant risks for developing PSD at 6 months post-stroke. Stroke patients need to be asked about these events and treated for PSD.

Collaboration between pharmacy and laboratory: defining total allowable error limits for therapeutically monitored drugs.

OBJECTIVE: To define the total allowable variability that is clinically tolerated for certain drug assays performed by the therapeutic drug monitoring (TDM) laboratory at our institution. METHODS: The monthly coefficient of variation (CV) for 13 of the most commonly performed drug assays was recorded for two concentrations: the upper and lower limits of the therapeutic range for each drug. A dosing simulation was performed for each drug by using population parameters to estimate the doses that would yield the two target concentrations in an adult patient. The smallest practical dosage adjustment that could be implemented in clinical practice was determined and the serum concentration resulting from this dosage change was estimated. Each change was equated to two standard deviations from the original drug concentration, and the corresponding CV or total allowable error (TEa) was calculated and compared with the laboratory's CV value. RESULTS: The laboratory CV was greater than the clinically defined TEa for amikacin at both trough and peak ranges, and for gentamicin and tobramycin at the trough range. Simulations for a patient with compromised renal function produced TEa values less than the reported CV for amikacin at both trough and peak ranges. Simulations for an obese patient produced TEa values less than the reported CV for amikacin, gentamicin, and tobramycin at both trough and peak ranges. The assay variability for these aminoglycosides is greater than the expected change in serum drug concentrations produced by the dosage changes used in the simulations. The TEa for all other drugs exceeded the laboratory CV, demonstrating assay variability within the clinically tolerated range. CONCLUSIONS: Knowledge of how the variability of a drug assay compares with its TEa allows clinicians to assess the usefulness of a serum drug concentration as a clinical tool.

Effect of protein concentration on the determination of digoxin in serum by fluorescence polarization immunoassay.

Determination of digoxin by fluorescence polarization immunoassay (FPIA) with the Abbott "TDx" is significantly influenced by the concentration of total serum protein. Each 10 g/L increase in serum protein results in an 8% decrease in measured digoxin. Studies with [3H]digoxin confirmed that digoxin binds to the protein pellet during the trichloroacetic acid precipitation step before the immunoassay. Serum protein, or equal concentrations of albumin or gamma-globulin, exert an equivalent effect on the apparent digoxin value. Because the total protein concentration of the assay calibrators is low (50 g/L) compared with its reference interval in serum (60-80 g/L), results by FPIA may be expected to be low by an average of 16% (range, 8-24%). Digoxin results by FPIA will be most nearly accurate when the calibrators include a total protein concentration of about 70 g/L. Patients' specimens with abnormally high or low protein content will give falsely high or low results for digoxin.

Validity of the Orientation Log, relative to the Galveston Orientation and Amnesia Test.

OBJECTIVE: To establish the validity of the Orientation Log (O-Log) by comparison with the Galveston Orientation and Amnesia Test (GOAT). DESIGN: Correlation of daily measures of orientation. SETTING: Acute rehabilitation hospital. SUBJECTS: Sixty-eight inpatients receiving rehabilitation following traumatic brain injury (TBI). PRIMARY MEASURES: The O-Log and GOAT. RESULTS: There was a significant correlation between the GOAT and O-Log (r = .901, P<.001). A cutoff of 25 on the O-Log was found to be comparable with the 75 cutoff on the GOAT. The scales were equivalent in measuring duration of posttraumatic amnesia. CONCLUSIONS: The O-Log is a valid measure of orientation for people with TBI and offers some advantages in administration over the GOAT.

Outcome after traumatic brain injury: pathway analysis of contributions from premorbid, injury severity, and recovery variables.

OBJECTIVE: To examine the relationship of premorbid variables, injury severity, and cognitive and functional status to outcome 1 year after traumatic brain injury (TBI) and to assess the feasibility of multivariate path analysis as a way to discover those relationships. DESIGN: Prospective, longitudinal. SETTINGS: Level I trauma center, acute inpatient rehabilitation hospital. PATIENTS: One hundred seven subjects (87 men, 20 women; mean age, 33.91 +/- 14.2 yr) who had experienced severe TBI, typically from motor vehicle crashes. INTERVENTIONS: Acute medical and rehabilitation care. MAIN OUTCOME MEASURES: Disability Rating Scale, Community Integration Questionnaire, and return to employment. Evaluated in acute rehabilitation, and at 6 and 12 months' postinjury. RESULTS: Path analyses revealed that premorbid factors had significant relationships with injury severity, functional skills, cognitive status, and outcome; injury severity affected cognitive and functional skills; and cognitive status influenced outcome. No significant relationships were found between injury severity and emotional status, injury severity and outcome, emotional status and outcome, and functional skills and outcome. CONCLUSIONS: Multivariate analysis is important to understanding outcome after TBI. Injury severity, as measured in this study, is less important to 12-month outcome than the premorbid status of the person and the difficulties (particularly cognitive deficits) exhibited at follow-up 6 months after the trauma.

Cognitive orientation in rehabilitation and neuropsychological outcome after traumatic brain injury.

This study evaluated the ability of the Orientation Log (O-Log) to predict cognitive outcome at rehabilitation discharge, as well as future neuropsychological outcome. The hypothesis was that patients who demonstrated better orientation upon admission would achieve superior functional cognitive outcome at discharge and on subsequent neuropsychological assessment. Sixty individuals receiving inpatient rehabilitation following a new-onset TBI participated. Orientation data was collected using the O-Log during morning bedside rounds. Outcome data was collected at 6 and 12 months post-injury. Significant correlations were found between the O-log and measures of memory, executive functioning, basic verbal skills, and estimated intellectual ability. When compared to the other predictor variables, step-wise multiple regression analyses revealed that the minimum O-Log score was the primary significant predictor of performance on six neuropsychological and functional outcome measures. Results of this study suggest that evaluating orientation with the O-Log during acute rehabilitation may reflect level of injury severity and aid in predicting cognitive outcome.

Cognitive and functional recovery at 6 and 12 months post-TBI.

Outcome studies examining recovery from traumatic brain injury (TBI) often fail to provide a clear understanding of the time course of cognitive, emotional, and behavioural recovery. The present study represents an effort to prospectively study individuals with TBI at fixed intervals, specifically 6 and 12 months post-injury with a window of +/- 1 month. Seventy-two individuals with new-onset TBI underwent neuropsychological evaluation and clinical interview at 6 and 12 months post-injury. Results revealed significant improvements in cognitive abilities, including memory, processing speed, language abilities, and constructional skills. There were significant gains in community integration and involvement in productive activities, but limitations in driving activities remained. Although individuals with mild-moderate TBI performed better than individuals with severe TBI, both groups demonstrated equivalent rates of recovery across domains. The results of this study provide important information regarding the time course of TBI recovery.

Rounded atelectasis: a new criterion for benignancy.

A malignancy must be considered whenever a mass lesion is encountered on a chest roentgenogram. Unless an unequivocal diagnosis of a benign lesion is made, thoracotomy is usually indicated. Rounded atelectasis, while only having been recently described, is being encountered with increasing frequency. As illustrated by our three cases, radiologic diagnosis of this entity is a major criterion for judging the benignity of a mass and obviates the need for a thoracotomy.

Ethylene glycol toxicity: the role of serum glycolic acid in hemodialysis.

OBJECTIVE: To correlate serum glycolic acid levels with clinical severity and outcome in ethylene glycol poisoning and to determine if glycolic acid levels are predictive of renal failure and the need for hemodialysis. METHODS: We measured serum ethylene glycol and glycolic acid levels by gas chromatography/mass spectrometry for 41 admissions (39 patients) for ethylene glycol ingestion and performed retrospective chart reviews. RESULTS: Eight patients died, all of whom developed acute renal failure. Of the survivors, 15 also developed acute renal failure, whereas 18 did not. Of those with normal renal function, 8 had glycolic acid levels below detection limits (< 0.13 mmol/L) despite ethylene glycol levels as high as 710 mg/dL; 7 of these patients coingested ethanol. Pertinent initial laboratory data for each group are as follows (mean; range): Deceased: pH 6.99 (6.82-7.22); bicarbonate, 4.8 mmol/L (2-9); anion gap, 28.6 mmol/L (24-40); glycolic acid, 23.5 mmol/L (13.8-38.0); ethylene glycol, 136.5 mg/dL (6-272). Survived/acute renal failure: pH 7.07 (6.75-7.32); bicarbonate, 5.6 mmol/L (1-12); anion gap, 28.7 mmol/L (18-41); glycolic acid, 20.2 mmol/L (10.0-30.0); ethylene glycol, 238.8 mg/dL (12-810). No acute renal failure with glycolic acid > 1.0 mmol/L: pH 7.29 (7.12-7.46); bicarbonate, 14.7 mmol/L (4-23); anion gap, 16.5 mmol/L (10-26); glycolic acid, 6.8 mmol/L (2.6-17.0); ethylene glycol, 269.1 mg/dL (6-675). No acute renal failure with glycolic acid < 1.0 mmol/L: pH 7.41 (7.38-7.47); bicarbonate, 23.4 mmol/L (17-25); anion gap, 11.8 mmol/L (8-18); glycolic acid, 0.1 mmol/L (0-0.66); ethylene glycol, 211 mg/dL (8-710). The mean time postingestion to admission generally correlated with severity as follows: deceased, > or = 10.4 h; survived/acute renal failure, > or = 9.9 h; no acute renal failure with glycolic acid > 1.0 mmol/L, > or = 6.2 h; no acute renal failure with glycolic acid < 1.0 mmol/L, > or = 3.7 h. Hematuria was more prevalent than oxaluria (86% and 41%, respectively), but neither was individually predictive of acute renal failure. Good correlations were found between glycolic acid levels and anion gap (r2 = 0.7724), pH (r2 = 0.7921), and bicarbonate (r2 = 0.6579); poor correlations (r2 < 0.0023) occurred between ethylene glycol levels and glycolic acid, pH, anion gap, and bicarbonate. Measured ethylene glycol values were highly correlated with ethylene glycol values calculated from the osmolal gap (r2 = 0.9339), but the latter overestimates the true value by about 7%, on average. An initial glycolic acid level > or = 10 mmol/L predicts acute renal failure with a sensitivity of 100%, a specificity of 94.4%, and an efficiency of 97.6%. Ethylene glycol levels are not predictive of acute renal failure or central nervous system manifestations of toxicity. If only ethylene glycol values are available (measured or calculated), an initial anion gap > 20 mmol/L is 95.6% sensitive and 94.4% specific for acute renal failure when ethylene glycol is present. Likewise, initial pH < 7.30 is 100% sensitive and 88.5% specific for acute renal failure. CONCLUSION: We propose glycolic acid > 8 mmol/L as a criterion for the initiation of hemodialysis in ethylene glycol ingestion. Patients with glycolic acid < 8 mmol/L probably do not need dialysis, regardless of the ethylene glycol concentration, when metabolism of ethylene glycol is therapeutically inhibited. In the absence of glycolic acid values, an anion gap > 20 mmol/L or pH < 7.30 predicts acute renal failure.

Exercise dysfunction in patients seropositive for the human immunodeficiency virus.

To confirm the presence of exercise dysfunction in patients seropositive for the human immunodeficiency virus (HIV), 32 such patients without AIDS were evaluated with cardiopulmonary exercise testing, pulmonary function testing, bronchoalveolar lavage, chest roentgenography, and gallium scanning. No evidence of pulmonary opportunistic infection was found. When compared to an otherwise similar group of HIV-seronegative controls, the patients exercised to a significantly lower workload (195 +/- 30 versus 227 +/- 31 W, p less than 0.001). The ventilatory anaerobic threshold (VAT) values were also significantly lower for the patients (49.2 +/- 13.0 versus 61.9 +/- 9.1% of maximum predicted VO2, p less than 0.001). Nine of the patients had VAT values less than the 95% confidence interval for the controls. This subgroup exercised to a significantly lower maximum VO2 (69.9 +/- 11.2 versus 95.9 +/- 17.5% of maximum predicted VO2, p less than 0.001) and workload (165 +/- 21 versus 227 +/- 31 W) when compared to the control group. These patients demonstrated a mild tachypnea throughout exercise relative to the controls and had a significant increase in the slope of the heart rate to VO2 relationship. These findings are most consistent with a limitation of oxygen delivery to exercising muscles, which may represent occult cardiac disease in this group.