Coma and impaired consciousness in the emergency room: characteristics of poisoning versus other causes.

OBJECTIVES: Unconscious patients represent a diagnostic challenge in the emergency room (ER), but studies on their characteristics are limited. The aim of this study was to investigate the frequency, characteristics and prognosis of different coma aetiologies with special focus on poisoning. DESIGN: An observational study of consecutive adults admitted to the non-surgical ER, with a Glasgow coma scale (GCS) score of 10 or below. The GCS score on admission was prospectively entered into a study protocol, which was complemented with data from the medical record within one month. RESULTS: 938 patients were enrolled. Poisoning caused unconsciousness in 352 cases (38%). In the remaining 586 cases (non-poisoning group) the underlying cause was a focal neurological lesion in 24%, a metabolic or diffuse cerebral disturbance in 21%, epileptogenic in 12%, psychogenic in 1% and was still not clarified at hospital discharge in 4%. Among patients below the age of 40 years, the coma was caused by poisoning in 80%, but among those over 60 years, poisoning was the cause in only 11%. The median GCS score on admission was identical in the two study groups. Hospital mortality rates were 2.8% and 39% in the two groups, respectively. CONCLUSION: Poisoning was the most common cause of coma and young age was a strong predictor of this condition. The prognosis was favourable among poisoned patients but poor in the rest of the study population as a group.

Primary deep vein thrombosis in the upper limb: A retrospective study with emphasis on pathogenesis and late sequelae.

BACKGROUND: Thrombosis of the upper extremity (UEDVT) is an uncommon disease with an incidence of 2-3% of all deep vein thromboses. The aim of this study was to determine the frequency of thrombophilia, post-thrombotic symptoms (PTS), and the rate of complications and recurrences in patients with primary UEDVT, which includes idiopathic and effort-related thrombosis. METHODS: Thirty-two patients with primary UEDVT were participants in the study. All patients with malignancies and intravenous devices were excluded. Two different scoring instruments - the Villalta and the DASH - were used to diagnose PTS, and a visual analogue scale (VAS) was used to estimate pain and disability. To evaluate working capacity, an arm exercise test was performed. Blood samples were taken for antithrombin, protein C and S deficiencies, antiphospholipid antibodies, mutation of factor V, fibrinogen, D-dimer, and von Willebrand factor antigen. RESULTS: None of the patients developed malignancy, pulmonary embolism, or recurrent UEDVT. Twenty-eight percent of the patients had mild to moderate PTS according to the scoring instruments. The arm exercise test and the VAS did not provide any additional information about the severity of PTS. The prevalence of thrombophilia was 40%; the most frequent disorders were the mutation of factor V (19%) and elevated fibrinogen (22%). CONCLUSIONS: This study supports the belief that primary UEDVT is a benign disorder with a low risk for recurrence but with a high frequency of PTS. For a majority of the patients, the underlying cause of the thrombotic event is unclear.

Hexafluorine vs. standard decontamination to reduce systemic toxicity after dermal exposure to hydrofluoric acid.

INTRODUCTION: Dermal exposure to hydrofluoric acid (HF) may cause severe burns and systemic toxicity. Hexafluorine (Prevor, France) is a product marketed as an emergency decontamination fluid for HF skin and eye exposures. Documentation concerning Hexafluorine is scanty, and a recent study indicates that its ability to reduce HF burns is at most equal to that of water. OBJECTIVE: The present study was conducted to evaluate Hexafluorine's capacity to reduce HF-induced systemic toxicity. METHODS: Sprague Dawley rats were anesthetized, catheterized in the left femoral artery, and shaved on their back. A filter paper (3.5 x 6 cm) was soaked in 50% HF and applied on the back of each rat for 3 min. Thirty seconds after removal of the paper, a 3-min rinsing with either 500 mL Hexafluorine (group H), 500 mL water (group W), or 500 mL water followed by a single application of 2.5% calcium gluconate gel (group Ca) was carried out. Blood samples were analyzed for ionized calcium and potassium (before injury and 1, 2, 3, and 4 h after) and also for ionized fluoride (1, 2, and 4 h after injury). RESULTS: The animals developed hypocalcemia, hyperkalemia, and hyperfluoridemia after the HF exposure. The only significant difference observed among the groups was in serum potassium at 1 h between group Ca and group W. However, there was a constant trend toward milder hypocalcemia and less pronounced hyperkalemia in group Ca compared to the other groups. There were no differences in the electrolyte disturbances between the Hexafluorine-treated animals and those treated with water only. Five of 39 animals died before completion of the experiment as a result of the HF exposure, one from group Ca and two from each of the other two groups. CONCLUSION: In this experimental study, decontamination with Hexafluorine was not more effective than water rinsing in reducing electrolyte disturbances caused by dermal exposure to hydrofluoric acid.

Topical treatments for hydrofluoric acid burns: a blind controlled experimental study.

BACKGROUND: Calcium gluconate gel, applied after initial rinsing with water, has a documented effect as first aid treatment for hydrofluoric acid burns. Hexafluorine is a novel liquid compound developed especially for emergency decontamination of hydrofluoric acid eye and skin exposures. However, scientific documentation of the effect of Hexafluorine is insufficient. This study was undertaken to compare Hexafluorine with water rinsing plus topical calcium and with water rinsing alone. METHODS: Thirty-five Sprague-Dawley rats were anesthetized and their backs shaved. Four filter papers 10 mm in diameter were soaked in 50% hydrofluoric acid and applied on the shaved area of each rat for 3 minutes. Thirty seconds later, the acid-exposed skin areas were rinsed with 500 mL Hexafluorine for 3 minutes (group H, n = 10), 500 mL water for 3 minutes (group W, n = 10) or 500 mL water for 3 minutes followed by a single application of 2.5% calcium gluconate gel (group Ca, n = 10), or received no treatment (controls, n = 5). The animals were closely observed for 5 days. Daily at 4 P.M. each of the four burns on every rat was rated on a modified Draize scale graded from 0 to 5 (0 = no visible injury, 1 = diffuse erythema, 2 = distinct erythema, 3 = distinct erythema plus wounds or discolored spots, 4 = distinct erythema plus wounds or discolored areas covering >50% of the burn, 5 = a necrotic wound covering the whole burn). The mean of the four scores was then calculated for each animal and day. The rating procedure was performed by one laboratory assistant who was unaware of the treatment given. Kruskal-Wallis analysis was used to evaluate possible differences between treatment groups on each of the 5 days. If the p-value obtained was <0.05, correction for multiple comparisons was made. RESULTS: The mean severity score in group H was significantly higher than that in group Ca on days 2 and 3. Moreover, Hexafluorine showed a consistent trend towards a worse outcome, both in comparison to water plus topical calcium and to water rinsing alone. CONCLUSION: Based on these observations it is concluded that water rinsing followed by topical calcium should remain the standard first aid treatment for skin exposure to hydrofluoric acid.

Predicting in-hospital mortality in acute myocardial infarction: impact of thrombolytic therapy on APACHE II performance.

OBJECTIVE: To study the usefulness of the Second Acute Physiology and Chronic Health Evaluation (APACHE II) scoring system for prognostication of in-hospital mortality in patients with acute myocardial infarction treated with thrombolysis. DESIGN: A prospective validation study was conducted at a medical intensive care unit at a university hospital. Over a 3-year period, 1714 patients with acute myocardial infarction were studied (mean age 72+/-10 years). Thrombolytic therapy was the prescribed treatment for 316 patients and total hospital mortality was 16%. RESULTS: The patients who received thrombolysis were younger, had higher blood pressure, lower heart and respiratory rates and higher Glasgow Coma Scale scores. Total in-hospital mortality was 9.5% in patients treated with thrombolysis and 17.1% in untreated patients (p < 0.01). Corresponding APACHE II predictions of mortality were 11.8 and 15.8% (p < 0.01). There was no significant difference between observed and predicted mortality. When a decision rule of 50% predicted risk of death was employed, sensitivity was 20% and specificity 99% in the thrombolytic group, while the corresponding figures in the nonthrombolytic group were 31% and 97%, respectively. CONCLUSIONS: In-hospital mortality in groups of patients treated with or without thrombolysis for acute myocardial infarction could be predicted with the APACHE II scoring system. Prognostication in individual patients is not possible with the APACHE II system.

Effects of ventilatory pattern on exhaled nitric oxide in mechanically ventilated rabbits.

BACKGROUND: Nitric oxide [NOexp] is present in exhaled air in many species. During experiments on pressure-controlled inverse ratio ventilation (PCIRV) in rabbits, increased [NOexp] was observed during PCIRV. The present study was undertaken to clarify which component of PCIRV increased [NOexp]. METHODS: Three groups of six New Zealand White rabbits were anaesthetised and mechanically ventilated. Exhaled nitric oxide, lung mechanics and gas exchange were measured using an experimental protocol designed to assess the effects of variations in 1) flow profile, 2) inspiratory time and 3) time-weighted tidal volume. Ventilator settings used were volume and pressure control ventilation at I:E ratios of 1:2 and 4:1. RESULTS: Constant and decelerating flow gave comparable [NOexp] levels (20.0 +/- 6.4 vs. 21.9 +/- 7.7 ppb, n.s.) when time-weighted tidal volume was kept constant. Using conventional (I:E 1:2) or inverted (I:E 4:1) I:E ratios in combination with decelerating flow and constant time-weighted tidal volumes did not alter [NOexp] (26.0 +/- 3.6 vs. 24.0 +/- 5.8 ppb, n.s.). An increased time-weighted tidal volume produced by pressure control with an I:E ratio of 4:1 increased [NOexp] (29.6 +/- 7.4) in comparison to constant (19.3 +/- 4.1, P < 0.05) and decelerating flow ventilation (19.6 +/- 3.6, P < 0.05) with I:E ratios of 1:2. CONCLUSION: The exhaled NO concentration was affected by ventilator setting. Increased levels of [NOexp] were observed with increases in time-weighted tidal volume, whereas changes in flow pattern and inspiratory time did not seem to influence airway NO production or release.

A placebo-controlled experimental study of steroid inhalation therapy in ammonia-induced lung injury.

BACKGROUND: The use of corticosteroids in toxic lung injury caused by exposure to an irritating gas such as ammonia has not been adequately studied. OBJECTIVE: To evaluate the effects of budesonide inhalation in a rabbit model of toxic lung injury induced by ammonia. DESIGN: Randomized, blind placebo-controlled laboratory investigation employing 16 New Zealand White rabbits. Lung injury was induced by inhalation of a defined amount of aerosolized ammonia. Thirty minutes later, the rabbits were randomized to receive either inhalation therapy with 0.5 mg budesonide or placebo. After another 2 hours, a second treatment inhalation, identical to the first one, was administered. RESULTS: Airway pressures, hemodynamics, and gas exchange were measured at baseline, 5, and 15 minutes after ammonia administration and every 30 minutes during a 6-hour period after the first blind inhalation of corticosteroids or placebo. The ammonia inhalation resulted in an acute severe lung injury, detected after 15 minutes as a decrease in Pao2 from 23.3 (+/- 3.6) to 11.0 (+/- 3.6) kPa (p < 0.005) and an increase in peak airway pressure from 13 (+/- 2) to 17 (+/- 2) cm H2O (p < 0.005). During the 6-hour observation period, the blood gas parameters improved gradually in all rabbits. In comparison with placebo, budesonide did not result in improved gas exchange or reduced airway pressure levels during the observation period. CONCLUSION: In this animal model corticosteroid inhalation therapy had no effect on ammonia-induced lung injury.

Pulmonary epithelial permeability and gas exchange: a comparison of inverse ratio ventilation and conventional mechanical ventilation in oleic acid-induced lung injury in rabbits.

STUDY OBJECTIVE: (1) To explore the interaction between mechanical ventilation and oleic acid (OA)-induced lung injury on indexes of pulmonary gas exchange and epithelial permeability, and (2) to compare this interaction using two different modes of ventilation: pressure-controlled inverse ratio ventilation (PCIRV) and volume-controlled ventilation with positive end-expiratory pressure (VCV PEEP). DESIGN: Randomized animal study. SETTING: Experimental laboratory investigation at Södersjukhuset, Stockholm, Sweden. ANIMALS: Twenty-four New Zealand white rabbits. INTERVENTIONS: (1) Ventilation with PCIRV (n=6) or VCV PEEP (n=6) for 6 h at equal end-expiratory alveolar pressure levels of 5 cm H2O followed by induction of lung injury (IV injection of OA 0.15 mL/kg). (2) Induction of lung injury followed by 6 h of ventilation with either PCIRV (n=6) or VCV PEEP (n=6) as described above. MEASUREMENTS AND RESULTS: Lung mechanics, heart rate, BP, and gas exchange results were equal at baseline. In group A, after 1 h of ventilation, mean airway pressure was 11.9+/-4.4 with PCIRV and 8.3+/-1.0 cm H2O with VCV PEEP (p<0.05). Forty minutes after OA injection, PaO2/fraction of inspired oxygen (FIO2) was 24+/-10 kPa with PCIRV and 44+/-15 kPa with VCV PEEP (p<0.05). Mean airway pressure was higher and peak airway pressure was lower with PCIRV. In group B, after 6 h of ventilation, PaO2/FIO2 was 17+/-5 kPa with PCIRV and 43+/-8 kPa with VCV PEEP (p<0.01). Systemic BP was lower with PCIRV and mean airway pressure was higher. Technetium-99m diethylene triamine penta-acetic acid lung clearance: In group A, curves were monoexponential with both PCIRV (half-life time [T 1/2], 21+/-8 min and VCV PEEP (T 1/2, 126+/-59 min, p<0.005) until injection of OA. In the VCV PEEP-treated animals, a marked increase in clearance rate was observed within 60 s of OA injection (T 1/2, 13+/-9 min, p<0.001). Fifteen minutes after OA injections, T 1/2 had decreased to 38+/-17 min with VCV PEEP. In the animals treated with PCIRV, OA injection did not lead to a significant change in clearance rate, although the elimination pattern was observed to change from single-compartment to multicompartment type. In group B, clearance curves were monoexponential with both ventilatory modes. There was no significant difference in clearance rate between PCIRV (T 1/2, 25+/-9 min) and VCV PEEP (T 1/2, 36+/-16 min, not significant). CONCLUSIONS: The observation that PaO2 was lower in the PCIRV-treated groups must be interpreted with caution in this animal study with relatively few observations. The finding may reflect differences in the effect of OA injection in the two ventilatory modes. It is also possible that externally applied PEEP is more effective than PCIRV in increasing oxygen tension, either because of a less inhomogenous distribution of ventilation and perfusion or for other reasons. The clearance results imply that PCIRV causes an alteration in lung epithelial or membrane function in comparison to VCV PEEP. This functional difference is most likely caused by the large time-weighted lung volume produced by pressure control in combination with a prolonged inspiration. Induction of high permeability lung injury with OA eliminates the difference between PCIRV and VCV PEEP. It remains to be established whether these findings are relevant with regard to ventilator-associated structural lung injury in man.

Fatal hyponatraemic brain oedema due to common gastroenteritis with accidental water intoxication.

Acute symptomatic hyponatraemia is a life-threatening emergency which must be diagnosed and treated promptly. The initial symptoms are often dramatic, with seizures and coma, and there is therefore a risk that the diagnosis and the urgent sodium correction therapy may be delayed by procedures such as computed tomography (CT) of the brain. As the most common aetiological factors are psychotic polydipsia and different iatrogenic causes, this condition usually develops in hospitalised patients. Water intoxication alone is very unlikely to cause severe hyponatraemia in a person with normal renal function, unless for some reason the antidiuretic hormone secretion is increased. We describe a case in which dehydration due to common gastroenteritis in combination with excessive intake of water caused the death of a young, previously healthy woman. Increased awareness of this potentially fatal condition is recommended.

A comparison of pressure- and volume-controlled ventilation at different inspiratory to expiratory ratios.

BACKGROUND: Inverse ratio ventilation (IRV) is frequently used in severe acute respiratory failure. IRV may lead to intrinsic positive end-expiratory pressure (PEEP) and is thought to improve oxygenation and to have advantageous effects on lung mechanics. Published data to support the use of IRV are scarce. This animal study compares external PEEP with intrinsic PEEP in pressure- and volume-controlled ventilation. METHODS: Fifteen pigs were randomly treated with 1. volume-controlled PEEP ventilation (I:E ratio 1:2) (VCV PEEP), 2. volume-controlled ventilation (I:E ratio 4:1) (VCIRV) and 3. pressure-controlled ventilation (I:E ratio 4:1) (PCIRV). Baseline measurements were performed using volume-controlled ventilation (I:E ratio 1:2) (VCV ZEEP). Lung mechanics, haemodynamics and gas exchange were measured by standard methods and functional residual capacity (FRC) by the sulphur hexafluoride technique. RESULTS: In comparison to VCV PEEP, PCIRV resulted in reduced peak airway pressure (32 +/- 3 vs. 27 +/- 6 cm H2O, P < 0.001) and increased mean airway pressure (14 +/- 2 vs. 22 +/- 5 cm H2O, P < 0.001). FRC was 942 +/- 264 ml in VCV PEEP and 1024 +/- 390 ml in PCIRV (n.s.). Oxygen delivery was lower in PCIRV (458 +/- 193 vs. 346 +/- 150 ml/min, P < 0.05). Physiologic dead space was 14 +/- 4% in PCIRV and 20 +/- 6% in VCV PEEP and VCIRV (P < 0.005). CONCLUSIONS: Inverse ratio ventilation did not result in improved FRC in comparison to conventional volume-controlled PEEP ventilation. PCIRV allows for a reduction in minute ventilation but the increase in mean airway pressure compromises circulation.

Pulmonary epithelial permeability. An animal study of inverse ratio ventilation and conventional mechanical ventilation.

STUDY OBJECTIVE: To compare pressure-controlled inverse ratio ventilation (PCIRV) with volume-controlled ventilation with positive end-expiratory pressure (VCV PEEP) at equal levels of end-expiratory alveolar pressure. The primary focus of the study was on pulmonary epithelial permeability. Histologic and gravimetric indicators of lung injury were also studied. DESIGN: Randomized animal study. SETTING: Experimental investigation at Södersjukhuset, Stockholm, Sweden. ANIMALS: Thirty-two New Zealand white rabbits. INTERVENTIONS: Ventilation with PCIRV or VCV PEEP for 6 h at an end-expiratory pressure level of 5 cm H2O. MEASUREMENTS AND RESULTS: Lung mechanics, heart rate, BP, and gas exchange. Measurement of pulmonary epithelial permeability by 99mTc-DTPA lung clearance. Extravascular lung water by gravimetric analysis. Morphology by light microscopy after a perfusion fixation procedure. Mean and peak airway pressures were 12.4 +/- 4.3 and 15.9 +/- 4.5 cm H2O with PCIRV and 8.6 +/- 0.8 (p < 0.001) and 19.9 +/- 4.1 cm H2O (p < 0.03) with VCV PEEP at 6 h. Mean systemic BP was lower with PCIRV (58 +/- 9 mm Hg) than with VCV PEEP (68 +/- 7 mm Hg) at 6 h (p < 0.003). At 6 h, PaCO2 was lower with PCIRV (3.2 +/- 0.6 kPa) than with VCV PEEP (4.1 +/- 0.8 kPa) (p < 0.02). There was no difference in blood oxygenation between PCIRV and VCV PEEP. 99mTc-DTPA lung clearance curves were monoexponential with both PCIRV and VCV PEEP. Mean lung clearance expressed as T 1/2 was 16 +/- 9 min with PCIRV and 107 +/- 74 min with VCV PEEP (p < 0.001). Morphologic examination revealed no differences between the groups and no evidence of significant lung injury. CONCLUSIONS: The observations reported in this article imply that PCIRV causes an alteration in lung epithelial or membrane function in comparison to VCV PEEP. This functional difference is most likely caused by the large time-adjusted lung volume produced by pressure control in combination with a prolonged inspiration. It remains to be established whether this early functional effect of PCIRV is relevant with regard to structural lung injury in mechanically ventilated subjects.

Suicidal chloral hydrate poisoning.

BACKGROUND: The cumulative reports of chlorate hydrate toxicity suggest an unacceptable risk for this commonly used sleep aid. CASE REPORT: A 29-year-old male was admitted after ingestion of 70 g of chloral hydrate. He was hypotensive and hypothermic. Spontaneous respiration was insufficient. Fluid resuscitation did not restore adequate blood pressure levels. Low dose catecholamine infusion resulted in ventricular arrhythmias. The patient was treated with combined hemoperfusion and hemodialysis during an eight hour period. During this time, serum concentrations of trichlorethanol fell. Blood pressure and heart rate increased and consciousness was regained without signs of neurological deficits. CONCLUSIONS: Although outcome was favorable, this case report illustrates the potentially high acute toxicity of chloral hydrate and supports its removal from the market.

Volume-controlled inverse ratio ventilation in oleic acid induced lung injury. Effects on gas exchange, hemodynamics, and computed tomographic lung density.

STUDY OBJECTIVE: To compare volume-controlled inverse ratio ventilation (VCIRV) with volume-controlled ventilation with conventional inspiratory to expiratory (I:E) ratio (VCV PEEP) at equal levels of end-expiratory pressure. DESIGN: Animal study using an oleic acid lung injury model with random application of VCV PEEP and VCIRV. SETTING: Experimental investigation at the Department of Clinical Physiology at Uppsala University. ANIMALS: Seven pigs. INTERVENTIONS: VCV PEEP, VCIRV at an end-expiratory pressure level of 10 cm H2O. MEASUREMENTS AND RESULTS: Lung mechanics, hemodynamics, gas exchange, and functional residual capacity. Recruitment of lung tissue, regional lung density, and distribution of inspired gas by computed tomography. Mean and peak airway pressures were 22 +/- 4 and 41 +/- 8 cm H2O with VCIRV and 18 +/- 2 and 45 +/- 7 cm H2O with VCV PEEP. Cardiac output and arterial oxygen tension were equal with VCV PEEP and VCIRV as were static compliance, physiologic dead space, and functional residual capacity. End-expiratory, end-inspiratory, and CT densities during a full ventilatory cycle were not statistically different and the amounts of nonaerated and poorly aerated lung areas were of equal size with VCV PEEP and VCIRV. CONCLUSIONS: VCIRV was comparable to VCV PEEP at similar PEEP levels in alveolar recruitment, aeration of the lung tissues, and in oxygenating the blood. Since cardiac output also remained unchanged, oxygen delivery to peripheral tissues did not differ significantly between the two modes. Neither method has thus proved superior to the other one.

Assessment of respiratory system compliance by a flow recording method.

Standard methods for the assessment of the compliance of the respiratory system require recordings of both airway pressure and ventilatory volume. A method based on the recording of respiratory flow only, with no need of measuring airway pressure was reported some years ago. The purpose of the present study was to test a modification of this flow-recording technique. The technique is based on the measurement of inspiratory flow with and without the addition of a source of external compliance added to the inspiratory circuit. The difference in inspiratory flow between these two situations can be used to derive the compliance of the respiratory system. The method was and in patients with acute respiratory failure, and compared with a standard method based on airway pressure and inspiratory gas flow recording. Model experiments showed strong correlation between the new flow-recording method and the standard method (r = 0.99, P < 0.001) with a coefficient of variation of less than 2% with both methods. In patients with acute respiratory failure, the flow and standard methods gave similar results when no end-inspiratory pause was applied (mean difference 5 +/- 40 ml/kPa (x +/- s.d.)). The standard method gave significantly higher compliance values, different from the flow method, when an end-inspiratory pause of 10% was applied (mean difference 53 +/- 2 ml/kPa, P < 0.01). The flow method was not influenced by the use of an end-inspiratory pause.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Physiology and Chronic Health Evaluation II scoring system in acute myocardial infarction: a prospective validation study.

OBJECTIVE: To study the usefulness of the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system for prognostication of inhospital mortality in acute myocardial infarction. DESIGN: A prospective validation study. SETTING: A medical intensive care unit (ICU) at a university hospital. PATIENTS: Over a 3-yr period, 2,007 admissions of 1,714 patients with acute myocardial infarction were studied. In readmissions to the medical ICU during the same hospital stay, only the first admission was studied. MEASUREMENTS AND MAIN RESULTS: Mean age of the patients was 72 +/- 10 yrs. The medical ICU mortality rate was 13% and total hospital mortality rate was 16%. Mean APACHE II score was 11.6 +/- 6.5. There was a close correlation between observed and predicted mortality rates in classes of patients with various APACHE II scores. Observed mortality in patients with scores of 20 to 24 was higher than the predicted mortality (p < .03). In this subgroup, 25% of the patients had a length of stay in the medical ICU of < 8 hrs. CONCLUSIONS: Inhospital mortality in patients with acute myocardial infarction could be accurately predicted with APACHE II scores. Prognostication was not as good in patients with a length of stay in the medical ICU of < 8 hrs.

Evaluation of a knowledge-based decision-support system for ventilator therapy management.

Evaluation of knowledge-based systems differs from that of conventional systems in terms of verification and validation techniques. Furthermore, evaluating medical decision-support systems is difficult because the field is thus far comparatively unexplored. This paper presents an evaluation of a medical knowledge-based system called VentEx that supports decision-making in the management of ventilator therapy. Real patient data from 1300 hours of patient care involving 12 patients with 6 diagnoses are used to validate the knowledge base. The results range from 4.5% to 15.6% disagreement between the setting recommendations produced by VentEx and a gold standard, and 22.2% disagreement for recommendations for weaning. A comparison between the standard and two physicians showed that VentEx produced advice of the same quality as the physicians.

Factitious disorder presenting with acute cardiovascular symptoms.

A 23-year-old female student exhibited all the characteristics of chronic factitious disorder with physical symptoms (Munchhausen's syndrome): deliberate simulation of illness, peregrination, fantastic pseudology and dramatic circumstances on admittance. The patient induced impressive blood pressure peaks by the Valsalva manoeuvre. She also simulated arrhythmias, seizures and unconsciousness. Her symptoms had previously led to comprehensive cardiological, neurological and endocrinological evaluations and treatment in at least three different countries in two continents. A literature survey suggests that facitious cardiovascular symptoms have become more frequent during recent decades.