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Biomedical subjects

J Christenson

Publications and source records attributed to J Christenson.

At least 19 recordsLinked to original sources
PubMed2000

A randomized trial of the effects of early cardiac serum marker availability on reperfusion therapy in patients with acute myocardial infarction: the serial markers, acute myocardial infarction and rapid treatment trial (SMARTT).

OBJECTIVES: The purpose of this study was to assess whether the immediate availability of serum markers would increase the appropriate use of thrombolytic therapy. BACKGROUND: Serum markers such as myoglobin and creatine kinase, MB fraction (CK-MB) are effective in detecting acute myocardial infarction (AMI) in the emergency setting. Appropriate candidates for thrombolytic therapy are not always identified in the emergency department (ED), as 20% to 30% of eligible patients go untreated, representing 10% to 15% of all patients with AMI. Patients presenting with chest pain consistent with acute coronary syndrome were evaluated in the EDs of 12 hospitals throughout North America. METHODS: In this randomized, controlled clinical trial, physicians received either the immediate myoglobin/CK-MB results at 0 and 1 h after enrollment (stat) or conventional reporting of myoglobin/CK-MB 3 h or more after hospital admission (control). The primary end point was the comparison of the proportion of patients within the stat group versus control group who received appropriate thrombolytic therapy. Secondary end points included the emergent use of any reperfusion treatment in both groups, initial hospital disposition of patients (coronary care unit, monitor or nonmonitor beds) and the proportion of patients appropriately discharged from the ED. RESULTS: Of 6,352 patients enrolled, 814 (12.8%) were diagnosed as having AMI. For patients having AMI, there were no statistically significant differences in the proportion of patients treated with thrombolytic therapy between the stat and control groups (15.1% vs. 17.1%, p = 0.45). When only patients with ST segment elevation on their initial electrocardiogram were compared, there were still no significant differences between the groups. Also, there was no difference in the hospital placement of patients in critical care and non- critical care beds. The availability of early markers was associated with more hospital admissions as compared to the control group, as the number of patients discharged from the ED was decreased in the stat versus control groups (28.4% vs. 31.5%, p = 0.023). CONCLUSIONS: The availability of 0- and 1-h myoglobin and CK-MB results after ED evaluation had no effect on the use of thrombolytic therapy for patients presenting with AMI, and it slightly increased the number of patients admitted to the hospital who had no evidence of acute myocardial necrosis.

Biomarkers↗
PubMed2000

A community pseudo-outbreak of invasive Staphylococcus aureus infection.

Outbreaks of invasive infection caused by methicillin-susceptible and methicillin-resistant Staphylococcus aureus occur in hospitals, long term care institutions, and in patients discharged from these settings. In contrast, epidemic S. aureus infection has not been reported in well persons in the community. Here, we describe a group of healthy young adults who resided in the same neighborhood and participated together in school sports, and who developed serious S. aureus infections within 3 weeks of each other, suggesting a true community outbreak. Timely use of molecular epidemiological tools, however, demonstrated that their illnesses were caused by unrelated bacterial strains.

Adolescent↗
PubMed2000

Early discharge of patients with presumed opioid overdose: development of a clinical prediction rule.

OBJECTIVE: To develop a clinical prediction rule to identify patients who can be safely discharged one hour after the administration of naloxone for presumed opioid overdose. METHODS: Patients who received naloxone for known or presumed opioid overdose were formally evaluated one hour later for multiple potential predictor variables. Patients were classified into two groups: those with adverse events within 24 hours and those without. Using classification and regression tree methodology, a decision rule was developed to predict safe discharge. RESULTS: Clinical findings from 573 patients allowed us to develop a clinical prediction rule with a sensitivity of 99% (95% CI = 96% to 100%) and a specificity of 40% (95% CI = 36% to 45%). Patients with presumed opioid overdose can be safely discharged one hour after naloxone administration if they: 1) can mobilize as usual; 2) have oxygen saturation on room air of >92%; 3) have a respiratory rate >10 breaths/min and <20 breaths/min; 4) have a temperature of >35.0 degrees C and <37.5 degrees C; 5) have a heart rate >50 beats/min and <100 beats/min; and 6) have a Glasgow Coma Scale score of 15. CONCLUSIONS: This prediction rule for safe early discharge of patients with presumed opioid overdose performs well in this derivation set but requires validation followed by confirmation of safe implementation.

Adult↗
PubMed2000

The incidence and pathogenesis of cardiopulmonary deterioration after abrupt withdrawal of inhaled nitric oxide.

We studied the effect of abrupt discontinuation of inhaled nitric oxide (iNO) in patients receiving this drug for treatment of acute hypoxemic respiratory failure (AHRF), in order to determine the need for continued therapy, the incidence and nature of adverse events, and the risk factors predicting these adverse events. Thirty-one patients who showed an initial increase in Pa(O(2)) of > 20 mm Hg in response to iNO underwent a discontinuation trial at 10 to 30 h after beginning iNO. Indwelling arterial and pulmonary artery catheters facilitated monitoring of hemodynamic and gas-exchange parameters. For the group, discontinuation of iNO caused a significant decrease in Pa(O2 ), arterial and mixed venous oxygen saturation, and ratio of Pa(O(2)) to fraction of inspired oxygen (FI(O(2))). Three patterns of response were observed. Eight of 31 (25.8%) patients had minimal changes in oxygenation or hemodynamics, suggesting no need for ongoing therapy. Fifteen of 31 (48%) patients had worsened gas exchange as a predominant response. Eight of 31 patients exhibited hemodynamic collapse, defined as > 20% fall in cardiac output and/or mean arterial blood pressure. In this last subgroup, the pattern of cardiovascular changes suggested that this response arose from an acute increase in right ventricular afterload, and was not a consequence of gas-exchange abnormalities. In all cases, reinstitution of iNO promptly reversed worsened hemodynamics and gas exchange. Independent factors associated with an increased risk of cardiovascular collapse included multisystem organ failure, older age, and initial blood pressure increase in response to iNO; a smaller change in the ratio of Pa(O(2)) to FI(O(2)) with initiation of iNO therapy also tended to correlate with this phenomenon. We conclude that careful and monitored discontinuation of iNO in patients with AHRF will identify substantial fractions of patients who are either receiving no benefit from this therapy or who require iNO to maintain an adequate circulation and are therefore at risk for adverse outcome with transport or inadvertent discontinuation of iNO. Future trials of iNO should recognize this complication of such therapy and include assessments for it.

Acute Disease↗
PubMed1999

Pre-emptive use of aerosolized ribavirin in the treatment of asymptomatic pediatric marrow transplant patients testing positive for RSV.

Respiratory syncytial virus is a common virus which frequently causes severe lower tract disease in immunocompromised patients. The mortality rate in bone marrow transplant patients with lower tract disease varies from 31% to 100%, depending upon the treatment used, time before initiation of treatment, and whether patients are pre- or post-engraftment. Therapy with inhaled ribavirin has been used with limited success in decreasing mortality rate. Because of concern about conversion from upper respiratory tract disease to lower respiratory tract disease, we conducted a pilot study using aerosolized ribavirin in asymptomatic RSV-positive patients. Patients had NP washes performed on a weekly basis during the RSV season, for the presence of RSV. If patients were positive, but asymptomatic, and could have their transplant postponed, they were treated with ribavirin until negative. Patients who could not be postponed received aerosolized ribavirin, and began transplant conditioning. During this study, we performed 145 nasal aspirations for RSV on 25 patients; 10 aspirates were positive in seven asymptomatic patients. All positive events were successfully treated with ribavirin, which cleared the RSV for a minimum of 3 weeks. No patients became symptomatic. Thus, we conclude that ribavirin can clear asymptomatic infections in immunocompromised pediatric transplant patients.

Adolescent↗
PubMed1999

Response to inhaled nitric oxide in patients with acute right heart syndrome.

Inhaled nitric oxide (iNO), a selective pulmonary vasodilator, has been shown to decrease pulmonary artery pressures but not increase cardiac output in hemodynamically stable patients with a variety of causes of pulmonary hypertension. The response to iNO in hemodynamically unstable patients with acute right heart syndrome has not been previously described. We determined the response to iNO in 26 critically ill adult patients with acute right heart failure defined by echocardiographic criteria. Patients received iNO through the inspiratory limb of the ventilator in increments of 10 ppm with hemodynamic and gas-exchange measurements made before and after each level. When maximal effect was seen, iNO was discontinued to compare parameters with baseline. iNO significantly increased cardiac output (5.5 +/- 3 to 6.4 +/- 4 L/min), stroke volume (54 +/- 27 to 65 +/- 38 ml), and mixed-venous oxygen saturation (69 +/- 8 to 73 +/- 10%), all p < 0.01. With discontinuation of iNO, all parameters returned immediately to baseline. These parameters of improved perfusion were related to a decrease in pulmonary vascular pressures and resistance. In a subset of approximately 50% of patients, these changes were substantial (> 20%) and in approximately 25% of all patients, the improvement in hemodynamic measures permitted a decrease in other vasoactive drug administration. The mean concentration of iNO required to achieve these effects was 35 ppm, and 85% of patients exhibiting a substantial improvement in hemodynamics did so at a concentration of iNO of less than or equal to 40 ppm. Underlying causes of right heart failure and baseline hemodynamics did not predict response to iNO, but the use of alpha-agonist catecholamines did. We conclude iNO improves hemodynamics in patients with respiratory failure, shock, and right ventricular dysfunction. Although mortality was not a key end point in this pilot study, it was high for both responders and nonresponders to this therapy. Further evaluation of the role of iNO in this patient population is supported by these data.

Acute Disease↗
PubMed1999

Outcomes of critically ill cancer patients in a university hospital setting.

Critically ill cancer patients constitute a large percentage of admissions to tertiary care medical intensive care units (ICUs). We sought to describe outcomes of such patients, and to evaluate how conditions commonly seen in these patients impact mortality. A total of 348 consecutive medical ICU cancer patients were evaluated. Subgroup comparisons included the three most common cancer types (leukemia, lymphoma, lung cancer), as well as three different treatments/conditions (bone marrow transplant [BMT] versus non-BMT, mechanical ventilation [MV] versus non-MV, neutropenic versus non-neutropenic). There were no mortality differences between patients with leukemia, lymphoma, or lung cancer. By logistic regression, mortality predictors were: MV, hepatic failure, and cardiovascular failure for the group as a whole (41% overall mortality); MV and allogeneic (as compared with autologous) BMT for the BMT group (39% overall mortality); hepatic failure, cardiovascular failure, and persistent acute respiratory distress syndrome (ARDS) for the MV group (67% overall mortality); and MV for the neutropenic group (53% overall mortality). Neutropenia showed no independent association with mortality in the group as a whole or any subgroup analyzed. We conclude that respiratory, hepatic, and cardiovascular failure predict mortality, whereas neutropenia does not. Additionally, we have noted an encouraging improvement in survival in many groups of critically ill cancer patients.

APACHE↗
PubMed1999

The incidence of and clinical variables associated with vancomycin-resistant enterococcal colonization in mechanically ventilated patients.

STUDY OBJECTIVES: (1) To determine in our ICU the incidence of vancomycin-resistant enterococcus (VRE) colonization in mechanically ventilated patients without a history of VRE infection or colonization; and (2) to determine the risk factors and outcome variables associated with VRE colonization in these patients. DESIGN: A prospective cohort study conducted between January 1996 and March 1998. SETTING: Medical and cardiac critical care units in a tertiary care urban university hospital. PATIENTS: Mechanically ventilated patients without evidence of pneumonia at the onset of ventilation. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Patients underwent rectal cultures by standard methods on day 1, day 3 or 4, day 6 or 7, and day 14 of intubation to detect VRE. Thirteen of 83 patients (16%) had rectal cultures positive for VRE (VRE+) at some point while being mechanically ventilated during their stay in the ICU. In comparison, approximately 15 of 2,100 medical ICU patients (0.7%) had clinical VRE infections as determined by the hospital's infection control program during a 2-year period. VRE+ patients had a higher incidence of immunosuppression than patients who had rectal cultures negative for VRE (VRE-) (9 of 13 [69%] vs 16 of 70 [23%], respectively; p < 0.01) and neutropenia (4 of 13 [31%] vs 5 of 70 [7%], respectively; p < 0.01). Hospital length of stay (LOS) was longer in VRE+ patients than in VRE- patients (27+/-17 days vs 17+/-14 days, respectively; p = 0.05), whereas pre-ICU hospital LOS and ICU LOS were similar in both patient groups. Five of 67 patients (7%) were VRE+ on day 1 of intubation, suggesting colonization at a prior site of care. Three of 29 patients who had subsequent rectal cultures converted to VRE+ while in the ICU. This group had a higher incidence of immunosuppression and neutropenia, and received more vancomycin compared with the patients who remained VRE- (p < 0.01). However, there was no significant difference in the use of other broad-spectrum antibiotics (such as antipseudomonal penicillins, third-generation cephalosporins, quinolones, and clindamycin), enteral tube feedings, or sucralfate between the two groups. In addition, a topical antibiotic paste (a gentamicin, nystatin, polymixin slurry) that was placed in the oropharynx to prevent bacterial overgrowth was not found to increase the incidence of VRE colonization in this patient population. CONCLUSIONS: The incidence of VRE colonization was surprisingly high: 16% in mechanically ventilated patients in a hospital in which VRE was not previously known to be endemic. Risk factors for the acquisition of VRE colonization included immunosuppression, neutropenia, and vancomycin use. Increased LOSs and hospital costs were seen in VRE+ patients compared to VRE- patients. Whether VRE colonization is a contributor to severe disease that leads to prolonged hospitalization and increased resource allocation or whether it is simply a marker of disease severity cannot be determined from this study. To the extent that specific antibiotic protocols are used to reduce antibiotic-resistant flora in the ICU, monitoring the incidence of VRE in the stool specimens of immunocompromised, mechanically ventilated patients can be a simple and useful tool to assess one effect of these strategies.

Anti-Bacterial Agents↗
PubMed1998

Altered neuronal activity rhythm and glutamate receptor expression in the suprachiasmatic nuclei of Trypanosoma brucei-infected rats.

The parasites Trypanosoma brucei cause African trypanosomiasis (sleeping sickness), a severe neuropsychiatric disease with marked disturbances of sleep-wake alternation. The sites of brain lesions are not well characterized. The present experimental investigation is focused on the hypothalamic suprachiasmatic nuclei, which play a role of a biological clock entraining endogenous rhythms in the mammalian brain. The electrophysiological properties of these neurons were analyzed in slice preparations from trypanosome-infected rats. The neuronal spontaneous activity, which shows a circadian oscillation, was markedly altered in the infected animals, displaying a reduced firing rate and phase advance of its circadian peak. The direct retinal fibers, which play a pivotal role in entrainment of the circadian pacemaker, displayed a normal density and distribution in the suprachiasmatic nuclei of infected animals after intraocular tracer injections in vivo. At the postsynaptic level, immunohistochemistry and Western blotting revealed in the suprachiasmatic nuclei of infected rats a selective decrease of the expression of glutamate AMPA GluR2/3 and NMDAR1 receptor subunits that gate retinal afferents. These data disclose an impairment of the neuronal functions in the biological clock in African trypanosomiasis, and may serve to unravel functional and molecular mechanisms behind endogenous rhythm disturbances.

Animals↗
PubMed1998

A comparison of multimedia and standard advanced cardiac life support learning.

OBJECTIVES: To compare student performance after Multimedia ACLS Learning System (MM) education compared with that after standard (ST) ACLS education. METHODS: Final-year medical students were divided into 2 groups based on convenience scheduling and given ACLS instruction either in a standard format or with the MM course. The sizes of the small groups and the times in small-group instruction were identical. All students were evaluated with the same 50-item multiple-choice written examination, a structured evaluation immediately after the management of a mock cardiac arrest, and a second structured evaluation of the same mock arrest (videotaped) by an instructor blinded to the education method. Students were assigned a mark from 1 to 5 in each of 4 domains: assessment, immediate priorities, continual assessment, and leadership. RESULTS: 75 students took the MM and 38 took the ST course. The mean +/- SD mark for the multiple-choice test was 89.3 +/- 4.9% (MM) vs 89.3 +/- 4.8% (ST); the on-site mock arrest evaluation mark (20 maximum) was 14.1 +/- 2.5 (MM) vs 14.1 +/- 2.0 (ST); and the blinded mock arrest evaluation was 13.1 +/- 2.9 (MM) vs 14.4 +/- 2.9 (ST) (p = 0.024). 1/75 (MM) vs 0/38 (ST) did not successfully complete the on-site mock arrest evaluation. More students in the MM group (46% vs 25%) required multiple attempts to successfully complete the mock arrest evaluation (p < 0.02). CONCLUSION: In medical students with no previous ACLS training, structured access to the multimedia ACLS Learning System provides immediate educational outcomes similar to those of a standard ACLS course. Multimedia computer-interactive learning should be enhanced with a short period of hands-on practice.

British Columbia↗