Validation and clinical feasibility of nitrogen washin/washout functional residual capacity measurements in children.

BACKGROUND: The functional residual capacity (FRC) is an important parameter in pediatric respiratory monitoring but it is difficult to assess in the clinical setting. We have introduced a modified N(2) washout method utilizing a change of F(I)O(2) of 0.1 for FRC measurement in adult respiratory monitoring. This study validated the algorithm in a pediatric lung model and investigated the stability and feasibility in a pediatric peri-operative and intensive care setting. METHODS: The lung model was ventilated in combinations of ventilatory modes, CO(2) production, model FRC and respiratory rates. Sixteen children from 10 days to 5 years were studied peri-operatively with controlled ventilation using a Mapleson D system and in the intensive care unit using a Servo-i ventilator in a supported spontaneous mode. FRC was measured during stable metabolic, respiratory and circulatory periods at positive end expiratory pressure of 3-4 and 7-8 cmH(2)O. RESULTS: In the model and in the clinical setting, we found an excellent agreement between washout and washin measurements of FRC as well as acceptable coefficients of repeatability. CONCLUSION: FRC was satisfactorily measured by a modified N(2) algorithm and may be included as a monitoring variable in pediatric respiratory care. Pediatric FRC monitoring demands strictly stable conditions as measurements are performed close to the limits of the monitor's specifications.

Monitoring functional residual capacity (FRC) by quantifying oxygen/carbon dioxide fluxes during a short apnea.

BACKGROUND: Clinically applicable methods for measuring FRC are currently lacking. This study presents a new method for FRC monitoring based on quantification of metabolic gas fluxes of O2 and CO2 during a short apnea. METHODS: Base line exchange of oxygen and carbon dioxide was measured with indirect calorimetry. End-tidal ( approximately alveolar) O2 and CO2 concentrations were measured before and after a short apnea, 8-12 s, and FRC was calculated according to standard washin/washout formulas taking into account the increased solubility of CO2 in blood when the tension is increased during the apnea. The method was tested in a lung model with CO2 excretion and O2 consumption achieved by combustion of hydrogen and implemented in six ventilator-treated patients with acute respiratory failure (ARF). RESULTS: In the lung model the method showed excellent correlation (r = 0.98) with minimal bias (34 ml) and a good precision, limits of agreement being 160 and -230 ml, respectively, compared to the reference method. In six ARF patients changes in FRC induced by increase or decrease in PEEP and measured with the O2/CO2 flux FRC method corresponded well with changes in reference values of FRC (r = 0.76-0.94). CONCLUSIONS: A new method has been proposed in which FRC could be monitored from measurements of physiological fluxes of gases during a short apnea with the use of standard ICU equipment and some calculations. We anticipate that with further development, this technique could provide a new tool for monitoring respiratory changes and ventilator management in the ICU.

Comparison of 0.5% intrathecal bupivacaine with 0.5% intrathecal ropivacaine in the treatment of refractory cancer and noncancer pain conditions: results from a prospective, crossover, double-blind, randomized study.

BACKGROUND AND OBJECTIVES: Intrathecal (IT) administration of bupivacaine (BUP) for treatment of "refractory" pain has sometimes been associated with unacceptable side effects. This study was undertaken to determine if IT-ropivacaine (ROP) can reduce the rate and intensity of these side effects e.g., urinary retention, paresthesia, and particularly, paresis with gait impairment. A prospective, crossover, double-blind, randomized study. METHODS: Twenty-one patients were enrolled, 9 dropped out of the study, and data were analyzed from 12 patients. Patients were treated by insertion of IT tunneled nylon catheters, continuous infusion of 0.5% ROP followed by 0.5% BUP or 0.5% BUP followed by 0.5% ROP solutions from an external electronic pump. Each local anesthetic was infused for 7 days, and their order of infusion randomized. The comparative efficacy of the ROP and BUP IT infusions was assessed from the daily doses of IT ROP and IT BUP, oral and parenteral opioids, and daily scores of nonopioid analgetic and sedative drug consumption. Self-reported pain intensity (visual analogue scale [VAS] mean scores) and scores of Bromage relaxation, ambulation, nocturnal sleep pattern, rates of side-effects attributable to the IT drugs, the patients' assessment of the IT ROP v the IT BUP periods of the trial, and the comparative daily cost of IT ROP v IT BUP were recorded. RESULTS: The daily doses of the local anesthetics used were 23% higher for ROP than for BUP. Further, the daily cost was approximately equals 3 times higher for ROP than for BUP. No other significant differences between IT ROP and IT BUP were found. CONCLUSION: The results of this study do not support the hypothesis that IT infusion of 0.5% ROP has advantages over IT infusion of 0.5% BUP when administered for relief of "refractory" pain.

Chromosome abnormalities in eighty-three head and neck squamous cell carcinomas: influence of culture conditions on karyotypic pattern.

Short-term cultures from 115 squamous cell carcinomas (SCC) of the head and neck were cytogenetically investigated. Thirty-six of the tumors have been reported previously, whereas 79 are new cases. The material was divided into two series based on the medium used. The 80 tumors of series I were cultured in RPMI 1640 supplemented with fetal calf serum, glutamine, antibiotics, insulin, cholera toxin, and epidermal growth factor. The 35 tumors of series II were cultured in a chemically defined, serum-free medium with a low calcium concentration, MCDB 153, which stimulates epithelial growth while inhibiting fibroblasts. A total of 83 tumors with clonal karyotypic abnormalities were detected in the two series. Series II had a higher proportion of tumors with complex karyotypic changes than series I (43% versus 15%), a lower proportion of tumors with pseudo- or neardiploid clones characterized by simple rearrangements (3% versus 34%), and a lower frequency of unrelated clones (3% versus 24%), indicating that the different culture conditions favored growth of different cell populations. Except for rearrangements of 1p22, which were mainly found in series I, the distribution of breakpoints in structural aberrations was similar in the two series and clustered to several chromosomal bands or regions, in particular 11q13, 1p22, 1p11-12, 3p11-q11, 5q13, 1q25, 15q10, and 8q10. Unbalanced structural aberrations were more common in series II, frequently leading to loss of segments from chromosome arms 3p, 7q, 8p, 11q, 13p, 14p, and 15p, whereas gain of genetic material often involved chromosome arms 1q, 3q, 8q, and 15q.

Embryonal rhabdomyosarcoma with 100 chromosomes but no structural aberrations.

An embryonal rhabdomyosarcoma was analyzed cytogenetically after short-term culturing. The tumor was located in the scrotum of an 18-year-old man who, at the age of 4, had been treated for a rhabdomyosarcoma in the orbita. The chromosome number was 100. No structural aberrations were present. There were 2-7 copies of each chromosome type with particular excess of chromosomes 8, 12, and 22, and a relative deficit of chromosome 15.