A Pumpless Pediatric Artificial Lung Maintains Function for 72 h Without Systemic Anticoagulation Using the Nitric Oxide Surface Anticoagulation System

BACKGROUND

Children with end-stage lung disease are commonly managed with extracorporeal life support (ECLS) as a bridge to lung transplantation. A pumpless artificial lung (MLung) is a portable alternative to ECLS and it allows for ambulation. Both ECLS and pumpless artificial lungs require systemic anticoagulation which is associated with hemorrhagic complications. We tested the MLung with a novel Nitric Oxide (NO) Surface Anticoagulation (NOSA) system, to provide local anticoagulation for 72 h of support in a pediatric-size ovine model.

METHODS

Four mini sheep underwent thoracotomy and cannulation of the pulmonary artery (inflow) and left atrium (outflow), recovered and were monitored for 72hr. The circuit tubing and connectors were coated with the combination of an NO donor (diazeniumdiolated dibutylhexanediamine; DBHD-N2O2) and argatroban. The animals were connected to the MLung and 100 ppm of NO was added to the sweep gas. Systemic hemodynamics, blood chemistry, blood gases, and methemoglobin were collected.

RESULTS

Mean device flow was 836 ± 121 mL/min. Device outlet saturation was 97 ± 4%. Pressure drop across the lung was 3.5 ± 1.5 mmHg and resistance was 4.3 ± 1.7 mmHg/L/min. Activated clotting time averaged 170 ± 45s. Methemoglobin was 2.9 ± 0.8%. Platelets declined from 590 ± 101 at baseline to 160 ± 90 at 72 h. NO flux (x10-10 mol/min/cm2) of the NOSA circuit averaged 2.8 ± 0.6 (before study) and 1.9 ± 0.1 (72 h) and across the MLung 18 ± 3 NO flux was delivered.

CONCLUSION

The MLung is a more portable form of ECLS that demonstrates effective gas exchange for 72 h without hemodynamic changes. Additionally, the NOSA system successfully maintained local anticoagulation without evidence of systemic effects.

In Vivo Testing of an Ambient Air Based, Portable, and Automated CO 2 Removal Controller for Artificial Lungs

Portable artificial lung (AL) systems are under development, but there are few technologies available that adjust the carbon dioxide (CO 2 ) removal in response to changes in patient metabolic needs. Our work describes the second generation of a CO 2 -based portable servoregulation system that automatically adjusts CO 2 removal in ALs. Four adult sheep (68 ± 14.3 kg) were used to test the servoregulator. The servoregulator controlled air sweep flow through the lung to meet a target exhaust gas CO 2 (tEGCO 2 ) level in normocapnic and hypercapnic (arterial partial pressure of CO 2 [PaCO 2 ] >60 mm Hg) conditions at varying flow rates (0.5-1.5 L/min) and at tEGCO 2 levels of 10, 20, and 40 mm Hg. In hypercapnic sheep, average post-AL blood partial pressure of CO 2 (pCO 2 ) values were 22.4 ± 3.6 mm Hg for tEGCO 2 of 10 mm Hg, 28.0 ± 4.1 mm Hg for tEGCO 2 of 20 mm Hg and 40.6 ± 4.8 mm Hg for tEGCO 2 of 40 mm Hg. The controller successfully and automatically adjusted the sweep gas flow to rapidly (<10 minutes) meet the tEGCO 2 level when challenged with changes in inlet blood flow or target EGCO 2 levels for all animals. These in vivo data demonstrate an important step toward portable ALs that can automatically modulate CO 2 removal and allow for substantial changes in patient activity or disease status in ambulatory applications.

New exposure-based metric approach for evaluating O(3) risk to North American aspen forests

The United States and Canada currently use exposure-based metrics to protect vegetation from O(3). Using 5 years (1999-2003) of co-measured O(3), meteorology and growth response, we have developed exposure-based regression models that predict Populus tremuloides growth change within the North American ambient air quality context. The models comprised growing season fourth-highest daily maximum 8-h average O(3) concentration, growing degree days, and wind speed. They had high statistical significance, high goodness of fit, include 95% confidence intervals for tree growth change, and are simple to use. Averaged across a wide range of clonal sensitivity, historical 2001-2003 growth change over most of the 26 Mha P. tremuloides distribution was estimated to have ranged from no impact (0%) to strong negative impacts (-31%). With four aspen clones responding negatively (one responded positively) to O(3), the growing season fourth-highest daily maximum 8-h average O(3) concentration performed much better than growing season SUM06, AOT40 or maximum 1h average O(3) concentration metrics as a single indicator of aspen stem cross-sectional area growth.

Association between particulate- and gas-phase components of urban air pollution and daily mortality in eight Canadian cities

Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on size-fractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporal variation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 microns in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 microns). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction may be a better predictor of mortality than mass alone. However, the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organic carbon be undertaken in Canadian urban environments to examine their potential effects on human health.

Gaseous emissions from vehicles in a traffic tunnel in Vancouver, British Columbia

In August 1995, measurements of CO, NO(x') speciated nonmethane hydrocarbons (NMHC), and CO2 were made in Vancouver's Cassiar Connector, a 730-m-long level-grade highway traffic tunnel. Two characteristics of the Vancouver setting are the presence of many propane vehicles and a mandatory inspection and maintenance (I/M) program. Although the driving conditions and vehicle fleets are otherwise outwardly similar to those of recent Tuscarora-tunnel studies, CO/NO(x) ratios at the Cassiar Connector are significantly lower than those measured at Tuscarora. The Cassiar measurements are consistent with the MOBILE5A mobile emissions model predictions. The Canadian version of MOBILE5A--known as MOBILE5C--gives nearly identical results, indicating that differences in Canadian and U.S. emission standards cannot explain differences between Cassiar and U.S. tunnels. Considering the modeling results as well as measured ethene/acetylene ratios indicative of noncatalyst vehicles, it appears that vehicle deterioration remains the major issue in in-use vehicle emissions--even in Vancouver, where there is a mandatory loaded-mode I/M program. Uncertainties in determining the ages of the vehicles in the tunnel, however, have a significant impact on the model predictions.

Associations between ambient particulate sulfate and admissions to Ontario hospitals for cardiac and respiratory diseases

The association of daily cardiac and respiratory admissions to 168 acute care hospitals in Ontario, Canada, with daily levels of particulate sulfates was examined over the 6-year period 1983-1988. Sulfate levels were recorded at nine monitoring stations in regions of southern and central Ontario spanned by three monitoring networks. A 13-micrograms/m3 increase in sulfates recorded on the day prior to admission (the 95th percentile) was associated with a 3.7% (p < 0.0001) increase in respiratory admissions and a 2.8% (p < 0.0001) increase in cardiac admissions. Increases were observed for all age groups examined. Admissions for cardiac diseases increased 2.5% for those under 65 years and 3.5% for those 65 years and older. After adjusting for ambient temperature and ozone, similar increases in respiratory admissions were observed in the period from April to September (3.2%) and in the period from October to March (2.8%). A 3.2% increase was observed for cardiac admissions in the period from April to September, and a 3.4% increase was observed in the period from October to March after adjusting for ambient temperature and ozone.

Effects of low ambient levels of ozone and sulfates on the frequency of respiratory admissions to Ontario hospitals

To investigate the acute respiratory health effects of ambient air pollution, the number of emergency of urgent daily respiratory admissions to 168 acute care hospitals in Ontario were related to estimates of exposure to ozone and sulfates in the vicinity of each hospital. Ozone levels were obtained from 22 monitoring stations maintained by the Ontario Ministry of the Environment for the period January 1, 1983 to December 31, 1988. Daily levels of sulfates were recorded at nine monitoring stations representing three different networks operated by the Ontario Ministry of the Environment and Environment Canada. Positive and statistically significant associations were found between hospital admissions and both ozone and sulfates recorded on the day of admission and up to 3 days prior to the date of admission. Five percent of daily respiratory admissions in the months of May to August were associated with ozone, with sulfates accounting for an additional 1% of these admissions. Ozone was a stronger predictor of admissions than sulfates. Positive and statistically significant (P < 0.05) associations were observed between the ozone-sulfate pollution mix and admissions for asthma, chronic obstructive pulmonary disease, and infections. Positive associations were also found in all age groups, with the largest impact on infants (15% of admissions associated with the ozone-sulfate pollution mix) and the least effects on the elderly (4%). Temperature had no effect on the air pollution-admission relationship. Ozone (lagged 1 day) and sulfates (lagged 1 day) displayed a positive association with respiratory admissions for 91 and 100% of the 168 acute care hospitals, respectively. Air pollution was not related to a class of nonrespiratory admissions, which served as a negative control, nor was it related to admissions in the winter months of December to March, when ozone and sulfate levels are low and when people spend a considerable amount of time indoors.

[Ureterorenoscopy as a diagnostic procedure in the upper urinary tract]

Ureteropyeloscopy has become a valuable asset in the diagnosis and treatment in the upper urinary tract. From 1984 to 1991 we performed 1635 ureteropyeloscopies, 180 procedures in a diagnostic intention. Rigid ureteropyeloscopes permit endoscopic access into the ureter and the upper calix, actively deflectable instruments are necessary to visualize the middle and lower calix.

[Treatment of distal urethral cancer by laser coagulation]

Primary carcinoma of the urethra is a rare lesion, and there are no standard therapeutical modalities suggested in the literature. We report the case of a 65-year-old woman with transitional cell carcinoma of the distal urethra and metastasis to the inguinal lymph nodes (T2 N1 MO G2). Locally, the lesion was treated by Nd:YAG laser coagulation in four sessions. Ileoinguinal and pelvic lymph-node dissection was performed as a diagnostic and therapeutic procedure. Twenty-eight months after the initial treatment, no evidence of tumor recurrence has been found, although extensive biopsy specimens have been taken. Clinical staging showed no evidence of metastases.