Carboxyhemoglobin half-life toxicokinetic profiles during and after normobaric oxygen therapy: On a swine model

Investigations on acute carbon monoxide (CO) poisoning struggle to highlight a relevant discriminant criterion related to CO poisoning severity for predicting complications, such as delayed neurological syndromes. In this context, it remains difficult to demonstrate the superiority of one method of oxygen (O2) administration over others or to identify the optimal duration of normobaric 100% oxygen (NBO) treatment. Myoglobin, as hemoglobin, are a potential binding site for CO, which could be a source of extravascular CO storage that impacts the severity of CO poisoning. It is not possible in routine clinical practice to estimate this potential extravascular CO storage. Indirect means of doing so that are available in the first few hours of poisoning could include, for example, the carboxyhemoglobin half-life (COHbt1/2), which seems to be influenced itself by the level and duration of CO exposure affecting this store of CO within the body. However, before the elimination of CO can be assessed, the COHbt1/2 toxicokinetic model must be confirmed: research still debates whether this model mono- or bi-compartmental. The second indirect mean could be the assessment of a potential COHb rebound after COHb has returned to 5% and NBO treatment has stopped. Moreover, a COHb rebound could be considered to justify the duration of NBO treatment. On an experimental swine model exposed to moderate CO poisoning (940 ppm for ±118 min until COHb reached 30%), we first confirm that the COHb half-life follows a bi-compartmental model. Secondly, we observe for the first time a slight COHb rebound when COHb returns to 5% and oxygen therapy is stopped. On the basis of these two toxicokinetic characteristics in favor of extravascular CO storage, we recommend that COHbt1/2 is considered using the bi-compartmental model in future clinical studies that compare treatment effectiveness as a potential severity criterion to homogenize cohorts of the same severity. Moreover, from a general toxicokinetic point of view, we confirm that a treatment lasting less than 6 hours appears to be insufficient for treating moderate CO poisoning.

Performance of age-adjusted D-dimer cut-off to rule out pulmonary embolism

BACKGROUND

Age-adjusted D-dimer cut-off has recently been proposed to increase D-dimer usefulness in older patients suspected of pulmonary embolism (PE).

OBJECTIVE

We externally validated this age-adjusted D-dimer cut-off using different D-dimer assays in a multicenter sample of emergency department patients.

METHODS

Secondary analysis of three prospectively collected databases (two European, one American) of patients suspected of having PE. D-dimer performance for ruling out PE was assessed by calculating negative likelihood ratio (nLR) for D-dimer with age-adjusted D-dimer cut-off (< age × 10 in patients over 50 years) and with conventional cut-off (< 500 μg dL(-1)). Test efficiency was assessed by the number needed to test (NNT) to rule out PE in one patient.

RESULTS

Among 4537 patients included, overall PE prevalence was 10.1%. In the overall population, nLR was 0.06 (95% confidence interval, 0.03-0.09) with conventional cut-off and 0.08 (0.05-0.12) with age-adjusted cut-off. Using age-adjusted cut-off, nLR was 0.08, 0.09 and 0.06 for Vidas(®) , Liatest(®) and MDA(®) assays, respectively. Use of age-adjusted cut-off produced a favorable effect on NNT in the elderly; the greatest decrease was observed in patients > 75 years: NTT halved from 8.1 to 3.6. The proportion of patients over 75 years with normal D-dimer was doubled (27.9% vs. 12.3%).

CONCLUSIONS

Our study shows that age-adjusted D-dimer had low nLR, allowing its use as a rule-out PE strategy in non-high pretest clinical probability patients, as well as using Vidas(®), Liatest(®) or MDA(®) assays. This age-adjusted cut-off increased clinical usefulness of D-dimer in older patients. A large prospective study is required to confirm these results.

European and American suspected and confirmed pulmonary embolism populations: comparison and analysis

BACKGROUND

If the prevalence of pulmonary embolism (PE) differs significantly between the US and Europe, this observation could reduce the generalizability of diagnostic protocols for PE derived in either location.

OBJECTIVE

To determine possible causes and potential clinical consequences of these PE prevalence differences.

METHODS

Secondary analysis of three prospectively collected multicenter samples (two French and one from the US) including 3174 European and 7940 American PE-suspected patients in Emergency departments (ED) (117 for Europe and 12 for US). Comparison of clinical features, resource use and outcomes of European- and US-suspected PE populations in ED.

RESULTS

European patients evaluated for PE were significantly older and had a higher clinical pretest probability (CPP) for PE. The final PE prevalence was significantly higher in Europe, in the overall sample (26.5% vs. 7.6%) and in each level of CPP. Suspected European patients categorized as low CPP had a higher posttest probability than US low CPP patients. Suspected US patients categorized as high CPP had a much lower posttest probability of PE than in Europe. The mean number of tests performed for one PE diagnosis was lower in Europe (7.4 vs. 21.6). Among patients diagnosed with PE, European patients had a higher mean severity of illness score and a higher PE-mortality rate (3.4% vs. 0.7%).

CONCLUSIONS

Among patients suspected of a PE and those ultimately diagnosed with a PE, European patients had higher acuity, a higher pretest probability and worse outcome than US patients. The present study underscores the importance of disease prevalence for pretest probability scoring approaches and for significance interpretation of imaging tests.

[The "Orf" virus: focus and review of the literature]

Orf is an infection often unknown to practicians throughout the world. The first known cases were registered at the end of the 19th century. The virus affects ovines and caprins and is characterized by cutaneous and/or mucosae lesions. It is strongly resistant and the survival time is important in the outside environment. The morbidity of Orf is far higher than its mortality. The virus is transmitted by direct and indirect contact among humans, who became vectors themselves. Those subjects that are in contact with the animals in question due to professional reasons are at risk in particular. The same goes for attendants and participants of religious feasts. The preferred localization of lesions in humans is the hands. The diagnostic is easily set by the anamnesis and the clinical characteristics of the lesions except when it happens to be a particular form. The complications are nearly exclusively related to the unawareness of the virus in form of inappropriate medical acts. The evolution is spontaneous and the unique treatment is the prophylaxis of bacterial infection as well as a constant surveillance.

Volumetric or time-based capnography for excluding pulmonary embolism in outpatients?

BACKGROUND

Volumetric capnography is technically more demanding but theoretically better than the time-based alveolar deadspace fraction (P(a)CO(2) - EtCO(2))/P(a)CO(2) as a bedside diagnostic tool for excluding pulmonary embolism (PE) in outpatients.

OBJECTIVE

We compared both diagnostic accuracy in patients with a suspected PE and positive D-dimer enzyme-linked immunosorbent assay results.

PATIENTS AND METHODS

In this clinical multicenter trial with prospective inclusion and 3-month follow-up, alveolar deadspace fraction was compared by receiver operating characteristic (ROC) analysis with other parameters derived from volumetric capnography.

RESULTS

Capnography was performed in 239 patients, and 205 tests (86%) were conclusive. The incidence of PE was 33%. The alveolar deadspace fraction accuracy expressed with ROC curve analysis was 0.73 +/- 0.04. The diagnostic performances of parameters from volumetric capnography were not significantly better. Sixteen per cent [95% confidence interval (CI) 12-21%] of patients presented a (P(a)CO(2) - EtCO(2))/P(a)CO(2) ratio under the cut-off value of 0.15, with a low clinical probability. This combination excluded PE, with a sensitivity of 96% (95% CI 89-99%) and a negative likelihood ratio of 0.17 (95% CI 0.09-0.33%).

CONCLUSION

Volumetric capnography failed to show superiority to alveolar deadspace fraction measurements [(P(a)CO(2) - EtCO(2))/P(a)CO(2)] for exclusion of PE in outpatients with positive D-dimer test results. Future studies should clarify the safety of excluding PE in patients combining low clinical probability with positive D-dimer results and (P(a)CO(2) - EtCO(2))/P(a)CO(2) ratios below the cut-off value of 0.15.

An unusual cause of abdominal pain

A 36-year-old woman presented to the Emergency Room because of abdominal pain associated with hematuria and red blood blending to stool. On admission, the physical examination revealed abdominal tenderness and diffuse cutaneous hematoma. The laboratory findings showed abnormal clotting tests with high International Normalised Ratio (INR) and prolonged activated partial thromboplastin time. Hemoperitoneum and ureteral hematoma were noted on the abdomen computed tomography. The patient confessed she had ingested difenacoum for several weeks. All the symptoms resolved with fresh frozen plasma perfusion and vitamin K.

[Validation of a triage scale: first step in patient admission and in emergency service models]

INTRODUCTION

At present, most emergency services handle the multitude of various demands in the same unity of place and by the same team of nurses aides, with direct consequences on the waiting time and in the handling of problems of varying degrees of importance. Our service examines other administrative models based on a triage of time and of orientation.

METHODS AND RESULTS

In a prospective study on 679 patients, we have validated a triage tool inspired from the ICEM model (International Cooperation of Emergency Medicine) allowing patients to receive, while they wait, information and training, based on the resources provided, in order to deal with their particular medical problem.

CONCLUSION

The validation of this tool was carried out in terms of its utilization as well as its reliability. It appears that, with the type of triage offered, there is a theoretical reserve of waiting time for the patients in which the urgency is relative, and which could be better used in the handling of more vital cases.

Survey of non-invasive ventilation for acute exacerbation of chronic obstructive pulmonary disease patients in emergency departments in Belgium

A study was undertaken to assess the availability and use of non-invasive ventilation (NIV) for the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD) in emergency departments in Belgium. A questionnaire was sent to the head physicians of 145 emergency departments (EDs) found in the list of the Belgian College of Emergency Physicians (BeCEP). Ninety eight questionnaires were analysed (representing 68% of the questionnaires sent). NIV was used in 49% of the EDs. In the hospitals where NIV was not used, the most important reasons given were no available equipment in 71%, lack of experience with this form of treatment in 32.7%, and more time consuming for physicians and nursing staff in 22.8%. Only 3.8% of the physicians doubted the benefit of NIV treatment. In the hospitals where NIV was used, the patient was watched during the first hour by one nurse only in 19.6%, by one physician in 8.6% and by a nurse and a physician in 54.5%. NIV was used for more than 4 h in 33% of EDs. Pressure-controlled ventilation (with home respirators) was used more often than volume-controlled ventilation.

Noninvasive ventilation for acute respiratory failure: a prospective randomised placebo-controlled trial

The aim of the present study was to clarify whether the known effects of noninvasive positive-pressure ventilation (NPPV) in patients with respiratory failure are real or due to placebo effects and whether early application of NPPV in the emergency department leads to rapid improvement of the patients condition and outcome. A prospective randomised placebo-controlled study was conducted in 20 patients with severe acute respiratory failure (ARF) secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD) or acute pulmonary oedema, not improving under conventional medical therapy and on the edge of intubation. Patients received either conventional medical therapy plus two-level NPPV (hi-level NPPV) or conventional medical therapy plus "placebo" NPPV. The main outcome measures involved the need for endotracheal intubation in the bi-level NPPV arm and in the placebo arm after crossing over to active NPPV. Morbidity, length of stay, mortality and the effect of the ventilatory mode on clinical, arterial-blood gas parameters, and the sternocleidomastoid muscles electromyogram (EMG) activity were also measured. The 10 patients in the active NPPV group rapidly improved and none needed intubation. Placebo NPPV resulted in no change in the clinical condition of patients that continued to worsen and the 10 patients were crossed over to active NPPV. Three patients were intubated. No differences in terms of morbidity, length of stay or mortality between the two groups were observed. Active NPPV (but not placebo NPPV) led to a rapid and significant improvement in the clinical parameters, pH and the carbon dioxide tension in arterial blood and to a decrease in respiratory frequency and sternocleidomastoid EMG activity. Early application of bi-level noninvasive positive-pressure ventilation in patients with severe acute respiratory failure, due to chronic obstructive pulmonary disease and acute pulmonary oedema, leads to a rapid improvement in clinical status and blood gases. Noninvasive positive-pressure ventilation had no placebo effect.

Determinants of Fi,O2 with oxygen supplementation during noninvasive two-level positive pressure ventilation

To maintain arterial oxygen saturation (Sa,O2) above 90% in patients with acute respiratory failure, oxygen (O2) is often added to the circuit of two-level noninvasive positive pressure ventilation (NPPV). However, the final inspiratory oxygen fraction (Fi,O2) is not known. To clarify this issue, the effect of different inspiratory positive airway pressures (IPAP) of the oxygen tubing connection site and the flow rate of O2, on Fi,O2 was assessed. The effects of the tidal volume (VT) and the respiratory rate on the Fi,O2 were then clarified in a model study. The Fi,O2 varied depending on the point where O2 was added to the circuit. When all other variables were constant, the connection closest to the exhaust port (ventilator side) gave the highest Fi,O2. Increases in IPAP led to decreases in Fi,O2. Finally, Fi,O2 increased with O2 flow, although it was difficult to obtain an Fi,O2 >0.30 unless very high O2 flows were used. Paradoxically, NPPV with low IPAP values and without O2 supplementation led to a Fi,O2 <0.21 at the circuit-patient interface. VT and respiratory rate did not appear to influence Fi,O2. To conclude, when using noninvasive positive pressure ventilation with two-level respirators, oxygen should be added close to the exhaust port (ventilator side) of the circuit. If inspiratory airway pressure levels are >12 cmH2O, oxygen flows should be at least 4 L x min(-1).

Epiploic appendagitis: color Doppler sonographic findings

The aim of this study was to analyze the color Doppler sonographic findings in primary epiploic appendagitis. Color Doppler sonographic findings of ten patients with primary epiploic appendagitis were reviewed. The following sonographic features were analyzed: identification of a mass adjacent to the colonic wall; identification of spotty color areas with arterial flow in this mass and detection of abnormalities of the colonic wall adjacent to the infiltrated fatty tissue. A well-delineated hyperechoic mass adjacent to the colonic wall was detected in each patient with sonography. No colonic wall abnormalities were observed nor color Doppler signal in and around the hyperechoic area. Absence of flow at color Doppler sonography is an additional feature of epiploic appendagitis.

PaCO(2)/ETCO(2) gradient: early indicator of thrombolysis efficacy in a massive pulmonary embolism

End tidal CO(2) measurement may be helpful in detecting the efficacy of thrombolysis after a massive pulmonary embolism. We report the case of a 76-year-old man with a massive pulmonary embolism, who required early intubation and mechanical ventilation. Thrombolysis with rtpA (total dosage: 60 mg) was initiated. During this procedure, clinical data, arterial blood gases and end-tidal CO(2) with a capnograph were recorded. Before thrombolysis the P(a-ET)CO(2) gradient was raised to 25 mmHg. During thrombolysis, the clinical data improved and the P(a-ET) gradient fell to 14 mmHg. We postulate that the P(a-ET)CO(2) gradient seems to be a reasonable indicator of efficacy of thrombolysis in this setting. However, the gradient did not return to normal values (4-5 mmHg). The possible reasons for this may be that during mechanical ventilation there was a large ventilation-perfusion ratio and the cardiac output may have still reduced. With these limitations, we conclude that the P(a-ET)CO(2) gradient should be evaluated as an indicator of pulmonary reperfusion in massive pulmonary embolism.

Two-level non-invasive positive pressure ventilation in the initial treatment of acute respiratory failure in an emergency department

There are few data on the use of two-level non-invasive positive pressure ventilation (two-level nIPPV) in the initial treatment of severe acute respiratory failure in emergency departments (ED). In a prospective, non-randomized, pilot study, we assessed (1) the feasability of this method in an ED, (2) its effect on clinical and laboratory data, and (3) its effect on the need of intubation and the final outcome of patients. During a 1-year period all eligible patients admitted for acute respiratory failure, with absence of improvement after periods of specific classic treatments, were included in the study. Each patient received a specific classic treatment and two-level nIPPV with a two-level positive pressure ventilator through a face mask. We recorded parameters on admission, after 15 and 45 minutes of nIPPV and at the end of nIPPV. Sixty-two patients were included: 29 with acute pulmonary oedema (APO), 16 with acute exacerbation of chronic obstructive pulmonary disease (COPD), four with asthma, and 13 with various diseases. In the APO-group, we observed a statistically significant improvement of respiratory and pulse rates, diastolic blood pressure, pH, PaCO2 and SaO2. In acute exacerbation of COPD, we observed only a statistical improvement of respiratory and pulse rates without any significant change of PaCO2 and pH. In the two other groups, there was a clinical, gasometric and haemodynamic improvement in all patients. Four patients were intubated and 10 died, but none in the ED or in the first 24 hours after hospital admission. We were able to institute two-level nIPPV for severe acute respiratory failure in an ED without complications. Its addition to the rest of classic specific treatment seems to bring about a rapid improvement of various clinical and laboratory parameters in most patients. We found no deleterious effect of nIPPV when implemented for short periods of time in the emergency department setting.

[Radiology and emergency medicine: state of the art]

Emergency medicine has emerged as a specific medical specialty for 30 years. To be efficient, the emergency clinician frequently needs the contribution of radiological examinations. This is the reason why emergency radiology has emerged as a new radiologic subspecialty. The aim of this paper is to review the recent history of emergency medicine and to summarize the present state of the radiological organisation for emergency care in the Western countries.

Nucleotide sequence of the restriction fragment Hind F-Eco RI2 of SV40 DNA

The nucleotide sequence of the SV40 genome region between the Hind K fragment and the Eco RI cleavage site has been determined by a combination of three different approaches : analysis of RNA products obtained by transcription with Escherichia coli DNA dependent RNA polymerase, partial degradations with snake venom exonuclease and base-specific chemical degradation of 5'-terminal labeled restriction fragments. This nucleotide sequence shows only one open reading frame and allows the deduction of a small segment of the amino acid sequence of VP1, the major structural protein.

Nucleotide sequence of the restriction fragments hind L and hind M of SV40 DNA

The nucleotide sequence of the two minor SV40 DNA restriction fragments Hind L and Hind M is here reported. For this purpose we used 5'-32p-labeled DNA fragments either partially digested with snake venom diesterase for analysis by the wandering spot method or partially degraded with the base specific reagents dimethylsulphate or hydrazine for direct sequence analysis on gel. In the former procedure the strands were separated before degradation, while in the latter the strands were separated after modification but before the degradation. Due to the presence of several termination codons, the region Hind L - Hind M cannot be translated in a polypeptide. Also, no initiation codons for protein synthesis are present in this region.