Production of nitrogen dioxide during nitric oxide therapy using the Servo Ventilator 300 during volume-controlled ventilation

BACKGROUND

Inhaled nitric oxide may be useful in the treatment of pulmonary hypertension and hypoxaemia. Nitric oxide is rapidly oxidized to nitrogen dioxide, which is toxic and may adversely affect the airways of the patient. The aim of the present investigation was to examine factors that may affect the concentration of nitrogen dioxide, using the Servo Ventilator 300 nitric oxide delivery system, where nitric oxide is flow-proportionally mixed with the main ventilatory flow in the proximal part of the inspiratory limb.

METHODS

In this experimental study nitric oxide and nitrogen dioxide levels were measured at the inspiratory site of a Y-piece with a chemiluminescence analyzer and electrochemical fuel cells. The effects of different concentrations of nitric oxide and oxygen, minute volume, different tube lengths, a soda lime absorber, and a humidifier placed in the inspiratory limb were evaluated.

RESULTS

The concentration of nitrogen dioxide was dependent on the concentrations and residence time of nitric oxide with oxygen and the minute volume ventilation used. A soda lime absorber reduced concentrations of nitrogen dioxide at the expense of almost corresponding reductions in inhaled concentrations of nitric oxide. A humidifier increased the concentration of nitrogen dioxide, to an extent depending on the water volume and temperature used.

CONCLUSION

Concentrations of nitric oxide and oxygen, minute volume ventilation, and residence time in the inspiratory part of the ventilatory circuit were factors that affected the generation of nitrogen dioxide. A soda lime absorber in this system is not recommended.

Evaluation of nitrogen dioxide scavengers during delivery of inhaled nitric oxide

We have analysed the ability of three nitrogen dioxide absorbing materials (soda lime, noXon and zeolite) to act as nitrogen dioxide scavengers during delivery of inhaled nitric oxide. Different mixtures of gas were produced in a ventilator (Servo Ventilator 300) and passed through an inspiratory tube. Concentrations of nitrogen dioxide and nitric oxide were measured in the distal part of the tube, with and without the gas having passed through a canister containing the different filter materials. Our findings indicated that nitrogen dioxide was absorbed effectively by all filter materials but that there was re-formation of nitrogen dioxide from nitric oxide and oxygen in or immediately after the canister. This initial production of nitrogen dioxide was very rapid and could not be prevented by the use of scavengers. Thus soda lime and zeolite had no practical effect as scavengers in this delivery system, and the effect of noXon was very slight.

Serum S-100 protein levels after pediatric cardiac operations: a possible new marker for postperfusion cerebral injury

BACKGROUND

The release of neuron-specific astroglial S-100 protein to the cerebrospinal fluid is a marker of cerebral damage. The aim of this study was to determine the pattern of release of S-100 protein to serum after pediatric cardiac operations and extracorporeal circulation.

METHODS

Sequential blood samples from 97 children (up to 16 years) were taken after induction of anesthesia, immediately after the discontinuation of extracorporeal circulation, and 5 and 15 hours after extracorporeal circulation. The children were divided into five groups including three age groups, children with Mb Down syndrome, and children undergoing circulatory arrest.

RESULTS

The serum concentrations of S-100 protein before the cardiac operation were found to be highest in neonates. Children with Down syndrome, regardless of age, had basal levels comparable to those in neonates. There was an increase in S-100 protein concentration immediately after extracorporeal circulation and a multivariate regression analysis showed this difference in S-100 protein concentration to be significant with respect to age (p = 0.002), perfusion time (p < 0.001), and circulatory arrest (p < 0.001), but the difference was not significant with respect to weight, Down syndrome, and core temperature (p > 0.8). In children younger than 1 month old and after circulatory arrest, levels of S-100 protein remained high at 5 hours after extracorporeal circulation.

CONCLUSION

These findings emphasize the necessity of using age-matched reference values and taking perfusion time into consideration when S-100 protein levels are evaluated with respect to cerebral postperfusion injuries in pediatric patients undergoing cardiac operations.

[A new study of patients with cancer in Umeå alternative medicine is no alternative]

A questionnaire study comprising 854 cancer patients in the Umeå health care region and covering the 10-year period, 1987-96, showed only a few cancer patients to use alternative medicine treatment for their disease. As compared with 19.4 per cent of 144 residents selected from the population register who answered the questionnaire in 1987, 16.8 per cent of the cancer patients reported using alternative treatments in 1987, 14.4 per cent in 1990, and 16.4 per cent in 1996. The commonest forms of alternative medicine used were chiropractic and acupuncture, and the majority of treatments were for pain in the muscles or musculoskeletal system.

Absorption of energy during vertical whole-body vibration exposure

Absorbed power (PAbs) during exposure to vertical whole-body vibration in a sitting posture was measured on 15 male and 15 female subjects. Different experimental conditions were applied, such as vibration level (0.5-1.4 m s(-2)) and frequency (2-100 Hz), body weight (54-93 kg) and, relaxed and erected upper body positions. Results show that PAbs was strongly related to the frequency of the vibration, peaking within the range of 4-6 Hz. The peak was predominantly located in the lower end of this range for females and for the relaxed sitting position. PAbs increased with acceleration level and body weight. Almost a ten-fold increase in PAbs was observed at the critical frequency when the vibration exposure was raised from 0.5 to 1.4 m s(-2). If risk assessment is based on the assumption that the amount of PAbs, independent of the frequency of the vibration, indicates a hazard, then the ISO-standard 2631 under- and overestimates the risk at frequencies below and above about 6 Hz, respectively. The results also indicate a need for differentiated guidelines for females and males. Many types of vehicles produce whole-body vibration with frequencies which coincide with the range where the highest PAbs was observed. PAbs is a 'new' concept for measurement of whole-body vibration exposure. Although not yet thoroughly evaluated, this measure may be a better quantity for risk assessment than those specified in ISO 2631 since it also takes the dynamic force applied to the human body into account.

Osteopromotive membranes enhance onlay integration and maintenance in the adult rat skull

This study aimed to evaluate the effect of an osteopromotive membrane technique on onlay bone graft survival. Unicortical bone grafts were positioned bilaterally below the temporal muscle in 21 adult Lewis rats. In 14 rats, the bone graft on the right side was covered by an expanded polytetrafluoroethylene GORE-TEX membrane, whereas that on the left side was left uncovered. Seven rats were killed after 12 (group 1) and 20 (group 2) weeks, respectively. The remaining animals (n = 7, group 3) received membranes bilaterally, of which the right-sided membrane was removed after 12 weeks, and these animals were killed after 20 weeks. The specimens were assessed by routine histology and immunohistochemical labelling for various matrix proteins. After 12 weeks (group 1), size differences between the sides were not significant, although all control onlay bone grafts showed microscopic signs of pronounced resorption. At 20 weeks (group 2), graft integration was more complete on the membrane side. For group 3, the height was significantly more preserved on the side where the membrane was not removed. Immunolabelling demonstrated a more intense bone remodelling at the membrane sites. Membrane treatment resulted in improved graft integration and significantly greater size persistence, but complete height was not maintained.

Production of nitrogen dioxide in a delivery system for inhalation of nitric oxide: a new equation for calculation

We have evaluated the kinetics of nitrogen dioxide production in a system for inhalation of nitric oxide. In addition to a small fraction of contamination of nitrogen dioxide in the nitric oxide stock gas, a considerable part of the total concentration of nitrogen dioxide is formed immediately after mixing of nitric oxide and oxygen. This initial build-up of nitrogen dioxide is followed by a linear, time-dependent increase in the concentration of nitrogen dioxide. An equation describing the concentration of nitrogen dioxide in the delivery system is formulated: [NO2] = kA x [NO] + kB x [NO]2 x [O2] + kC x t x [NO]2 x [O2], where nitrogen dioxide [NO2] and nitric oxide [NO] concentrations are in parts per million (ppm), oxygen concentration [O2] is expressed as a percentage and contact time (t) is in seconds. The rate constants are kA = 5.12 x 10(-3), kB = 1.41 x 10(-6) and kC = 0.86 x 10(-6). Calculated nitrogen dioxide values correlated well with measured concentrations. This new finding of an initial build-up of nitrogen dioxide has to be taken into consideration if the conversion of nitric oxide to nitrogen dioxide is to be calculated and in the safety guidelines for the use of nitric oxide.

Bone graft incorporation after cortical perforations of the host bed

A fundamental issue in onlay bone graft persistence is the unpredictable extent of incorporation and volumetric maintenance of the graft. The purpose of this study was to evaluate the effects on integration of onlays, with either their cancellous or cortical portion facing toward the host bed, positioned over cortical perforations at the recipient site. Tibial or femoral unicortical bone grafts were harvested from isogeneic donors and positioned subperiostally on each tibia of 22 adult Lewis rats. On the experimental side, the recipient outer cortical bone surface received multiple perforations, 0.25 mm in diameter. The contralateral side served as a control (no cortical perforations). The findings were assessed after 4 and 20 weeks using routine histologic and immunohistochemistry techniques. Cortical perforations induced a migration of the recipient bone marrow into the graft as well as a reduced size diminution. More cortical bone remodeling and marginal lamellar bone apposition were observed after orientating the cortical portion of the graft toward the recipient site. These observations may be useful clinically to improve long-term success after autogeneic bone grafting.

Bone Graft Incorporation after Cortical Perforations of the Host Bed

A fundamental issue in onlay bone graft persistence is the unpredictable extent of incorporation and volumetric maintenance of the graft. The purpose of this study was to evaluate the effects on integration of onlays, with either their cancellous or cortical portion facing toward the host bed, positioned over cortical perforations at the recipient site. Tibial or femoral unicortical bone grafts were harvested from isogeneic donors and positioned sub-periostally on each tibia of 22 adult Lewis rats. On the experimental side, the recipient outer cortical bone surface received multiple perforations, 0.25 mm in diameter. The contralateral side served as a control (no cortical perforations). The findings were assessed after 4 and 20 weeks using routine histologic and immunohistochemistry techniques. Cortical perforations induced a migration of the recipient bone marrow info the graft as well as a reduced size diminution. More cortical bone remodeling and marginal lamellar bone apposition were observed after orientating the cortical portion of the graft toward the recipient site. These observations may be useful clinically to improve long-term success after autogeneic bone grafting.

A delivery system for inhalation of nitric oxide evaluated with chemiluminescence, electrochemical fuel cells, and capnography

OBJECTIVE

To evaluate a system for delivery of inhaled nitric oxide.

DESIGN

Prospective, laboratory study.

SETTING

Engineering laboratory.

SUBJECTS

A standard ventilator (Servo Ventilator 300), supplemented with extra gas modules for nitric oxide delivery.

INTERVENTIONS

Two ventilator-integrated gas modules, delivering < or = 10 parts per million (ppm) or < or = 100 ppm of nitric oxide, were used in adult and neonatal modes during volume-controlled ventilation. Set nitric oxide concentration and FIO2 were systematically changed and compared with the measured concentration. Short-term mixing was tested in adult, pediatric, and neonatal modes by substituting nitric oxide with CO2, and measuring the delivered concentration by a fast-response CO2 analyzer during five successive respiratory cycles. Long-term mixing was tested with the administration of 25 ppm of nitric oxide for 7 days.

MEASUREMENTS AND MAIN RESULTS

Delivered concentration of nitric oxide and nitrogen dioxide were simultaneously measured at the Y-place by two methods-chemiluminescence and electro-chemical fuel cells. The maximum absolute difference between set and measured concentrations of nitric oxide in the adult mode was 0.6 ppm at a set concentration of 10 ppm and 2.7 ppm at a set concentration of 100 ppm. In the neonatal mode, the maximal difference was 3.1 ppm at a set concentration of 100 ppm. Nitrogen dioxide concentration increased with increasing concentration of nitric oxide and oxygen to 2.6 ppm (as measured by the chemiluminescence analyzer) and 3.6 ppm (as measured by the electro-chemical fuel cell), at a setting of 100 ppm of nitric oxide with an FIO2 of 0.90 in the neonatal mode (2 L/min). During the short-term test of mixing stability throughout the respiratory cycles, a constant set CO2 concentration varied maximally by +/-6.2% from the set value in the neonatal mode, whereas the variance was by +/-6.5% in pediatric mode, and by +/-8.0% in the adult mode. During the long-term test, nitric oxide concentration varied maximally by +/-2.6% (as measured by the chemiluminescence analyzer) and by +/-2.3% (as measured by the electrochemical fuel cell).

CONCLUSIONS

An accurate precision in delivered nitric oxide concentration was achieved during intermittent flow ventilation, and this accuracy was independent of tested ventilator settings. The delivery system administered an almost stable concentration throughout a respiratory cycle and during long-term delivery. If the mixing point is in the inspiratory part of the ventilator, valid measurement of nitric oxide and nitrogen dioxide delivery concentrations are possible. Both techniques for measuring nitric oxide and nitrogen dioxide have drawbacks.

Inhaled nitric oxide reveals and attenuates endothelial dysfunction after lung transplantation

BACKGROUND

Maintaining endothelial function within transplanted organs may be critical to successful preservation. In this study we have evaluated the relationship between the effect of inhalation of nitric oxide and the degree of endothelial dysfunction after lung transplantation.

METHODS

A left lung, which had been preserved for 24 hours, was transplanted and a right pneumonectomy was performed in 5 pigs. After a 24-hour observation period the pigs inhaled 5, 20, and 80 ppm nitric oxide, and pulmonary vascular resistance was recorded continuously. From the same donors preserved pulmonary arteries from the contralateral lung were studied simultaneously in organ baths. Acetylcholine chloride was used to elicit endothelium-dependent relaxation in vessel segments contracted with the thromboxane A2 analogue U-46619.

RESULTS

Maximal endothelium-dependent relaxation decreased in the preserved lungs and correlated to the pulmonary vascular resistance in the simultaneously transplanted lungs. Inhalation of nitric oxide in the pigs that had received transplants caused the pulmonary vessels to dilate in proportion to the endothelial dysfunction.

CONCLUSIONS

Preservation of lung for transplantation induces an endothelial dysfunction, and the degree of the decrease in pulmonary vascular resistance caused by nitric oxide inhalation may be an indication of the degree of this endothelial damage. The vasodilation caused by inhaled nitric oxide increases as the endothelial function deteriorates.

Strabismus in children with cerebral palsy

In 48 children with cerebral palsy the characteristics of the squint and amblyopia were analyzed, also with respect to the features of cerebral palsy and to birth weight. Strabismus of congenital esotropia type was found to be common, as was also exotropia of early onset. Spontaneous alternation or an accommodative component of the squint was present only in a few cases. There was no evidence of an accumulation of any strabismus type in the different subgroups of cerebral palsy, whereas amblyopia or an obvious risk for amblyopia was found in the great majority of the cases. Some kind of amblyopia treatment was given to 34. Most of them showed improvement of the visual capacity which encourages treatment of amblyopia, even in children with cerebral palsy.

Onlay bone graft behaviour after marrow exposure of the recipient rat skull bone

This study aimed to evaluate the effects on incorporation of onlay grafts after exposure of the marrow of the skull recipient bed. Tibial or femoral uni- and bicortical bone grafts were positioned subperiosteally or submuscularly in the parietal and temporal region, respectively, of 28 adult rats. The recipient bed was ground to remove the external cortical layer and expose the underlying marrow. The outcome was assessed after four, 12, and 20 weeks by routine histology and immunohistochemical labelling for various bone and cartilage proteins. Marrow exposure resulted in an explosive bone formation, prompt graft incorporation, earlier onset of bone remodelling, but also localized resorption at the host bed due to increased vulnerability to pressure. Graft height loss was similar relative to previous observations by us using the same experimental model but without exposure of the marrow. The investigated proteins were identified at various locations and with different temporal sequences; the technique contributed to a diversified appreciation of graft behaviour. The findings emphasize the essential role of the bone marrow constituents to bone graft incorporation.

Effect of cortical perforations of both graft and host bed on onlay incorporation to the rat skull

The mechanisms involved in the integration of autogeneic bone grafts still attract much interest due to their clinical importance. The purpose of this study was to obtain data on the effects of a combination of cortical bone perforations both at the recipient site and the inner layer of a bicortical graft. 12 adult rats obtained femoral or tibial bicortical bone grafts from isogeneic donors to the tibia, one on each leg. On the experimental side, both the recipient bed and the inner cortical graft layer received multiple perforations (0.25 mm in diameter), while on the control side, only perforations of the recipient cortical bed were made. The findings were assessed by routine histology and immunohistochemical analysis for some bone and cartilage matrix proteins after 4 and 20 weeks. The combined cortical perforations of the graft and the host bed induced a locally improved bony incorporation of the graft and a corticalization of the graft marrow, implying improved mechanical stability. The graft height persistence was similar between groups. Intense labelling of the bone matrix proteins was apparent in all bone tissue and by diversified intensity at its various components, demonstrating ongoing remodeling activities. PRELP and fibromodulin mainly outlined the soft tissues surrounding the graft and compact bone sealing off the graft marrow. Immunolabelling contributed a more delicate picture of the mechanisms involved in graft incorporation.

Effect of transforming growth factor-beta and platelet-derived growth factor-BB on articular cartilage in rats

The short-term and long-term effects on the growth zone in articular cartilage of transforming growth factor-beta 1 and platelet-derived growth factor-BB injected intraarticularly into the knee joint of growing rats were investigated. The changes induced by five injections of 0.5 micrograms of transforming growth factor-beta 1 included a rapid decrease in the size and number of hypertrophic cells and an enhanced subchondral bone formation. The changes were most marked in the patella but were also apparent in the tibia and femur. The proliferating cells became swollen and lost their normal organization. From the seventh day of the experiment to about 3 weeks, the matrix stained intensely with safranin O for proteoglycans. The alterations induced by transforming growth factor-beta also included synovial fibroplasia and synovitis, consisting predominantly of mononuclear cells. Localised necroses in the cartilage sometimes appeared after 21 days. In long-term studies, destroyed cartilage was found in three of six rats and partial ossification of the joint cartilage was found in two after 90 and 180 days. Ossicles developed in the tendons in all six patellae. Injection of platelet-derived growth factor-BB resulted in an early and transitory minor increase in the osteogenic activity in the zone between cartilage and red bone marrow and later produced an ossicle in one of four tendons. None of the other changes noted after injection of transforming growth factor was observed.

Influence of surrounding soft tissues on onlay bone graft incorporation

OBJECTIVES

This investigation aimed to evaluate the influence of three different soft tissue environments on onlay bone graft incorporation into the craniomaxillofacial skeleton and to follow this process immunohistochemically by staining for some bone and cartilage matrix proteins and proteoglycans.

STUDY DESIGN

Femoral and tibial bone grafts, either uni- or bicortical, were placed subperiosteally, submuscularly, and intramuscularly in 36 identically sized and aged isogeneic rats. The results were evaluated after 4, 12, and 20 weeks.

RESULTS

Corticocancellous grafts showed a more extensive incorporation and more pronounced local resorption. Bicortical grafts produced more resorption of the recipient site, which oftentimes resulted in the graft being almost level with the surrounding bone. The marrow space of both graft types was sealed off by compact bone formation. Intense labeling of tested bone matrix proteins at various parts of the graft-host area was demonstrated. Ultimate graft height was significantly reduced for most groups, but no major differences between groups were registered. Intramuscularly positioned control grafts ultimately showed signs of lacking viability and reduced labeling of cartilage matrix proteins.

CONCLUSIONS

These findings indicate that either type of graft had its drawbacks and that further studies to enhance integration and size maintenance are necessary to improve overall graft persistence. Immunolabeling may help to identify essential mechanisms in and find markers of graft incorporation.

Validation of nested Bordetella PCR in pertussis vaccine trial

A nested PCR, using a 239-bp sequence in the pertussis toxin promoter region, was developed and evaluated. The assay differentiates Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica by restriction enzyme analysis of the amplified fragments. The diagnostic performance of the PCR was evaluated in a Swedish pertussis vaccine efficacy trial which took place from 1992 to 1995, including study children and household members and using culture and serology for laboratory confirmation of suspected cases. In total 2,421 nasopharyngeal aspirates were analyzed. The total diagnostic sensitivity for B. pertussis was 90.2% (194 of 215). During the study period samples were processed with and without the cation-exchange resin Chelex. The PCR diagnostic sensitivity for B. pertussis among the Chelex-treated aspirates was 94.9% (75 of 79), and that for B. pertussis among 124 aspirates in a consecutive non-Chelex-treated material was 89.5% (111 of 124). After Chelex treatment of the 13 PCR-negative samples, an additional six became PCR positive, giving a final sensitivity of 94.3%. In addition, PCR was positive for B. pertussis with 57 of 1,744 samples negative by culture but with available serological data. The specificity of PCR with these samples was supported by a significant increase in antibody levels between acute and convalescent sera in 45 cases and by epidemiological or clinical data in all but two of the remaining cases. PCR was also positive for B. pertussis with 26 of 415 aspirates from episodes lacking serology. The diagnostic sensitivity of PCR for B. parapertussis was 74.0% (37 of 50). There were an additional seven culture-negative B. parapertussis PCR findings, six from cases with significant antibody increases against filamentous hemagglutinin only and one from a case lacking serology. There were no samples positive for B. bronchiseptica. In conclusion, PCR detection of B. pertussis and/or B. parapertussis enabled us to identify 90 positive nasopharyngeal aspirates, in addition to the 262 culture-positive samples (an increase of 34%). Relating these cases to serology and clinical data indicated a PCR specificity approaching 100%.

Inhalation of nitric oxide after lung transplantation

BACKGROUND

Pulmonary hypertension is a postoperative complication that may adversely affect the outcome of lung transplantation. The effect of nitric oxide (NO) inhalation on pulmonary hemodynamic indices after lung transplantation was studied and compared with findings in control pigs.

METHODS

Varying concentrations of NO were inhaled by 5 pigs after left lung transplantation and right pneumonectomy and by 5 controls after right pneumonectomy at an inspired oxygen fraction of 0.21 and 0.5. Hemodynamic data were recorded continuously, and fast circulatory courses were analyzed.

RESULTS

Inhalation of NO reduced pulmonary vascular resistance and mean pulmonary arterial pressure in all pigs, but the decrease was pronounced and dose dependent only at an inspired oxygen fraction of 0.21 in the pigs that had transplantation. These were the only pigs that became hypoxic. With the termination of NO, there was a dose-independent rebound pulmonary vasoconstriction in the controls, especially at an inspired oxygen fraction of 0.21, but not in the pigs that had transplantation. This response was transient and could be blunted with a higher inspired oxygen fraction.

CONCLUSION

Inhalation of NO reduced pulmonary vascular resistance in the transplanted lung and may be useful in the treatment of pulmonary hypertension after lung transplantation. The rebound pulmonary vasoconstriction with the termination of NO inhalation stresses the need to be aware of this effect and to wean NO carefully in clinical situations. This study showed oxygen dependency, which has to be taken into consideration in dose-response studies involving NO inhalation.

Trends in the relationship between breastfeeding and postpartum employment in the United States

It is widely assumed that employment and breastfeeding are relatively incompatible behaviors in the United States; yet recently both the incidence of breastfeeding and the incidence of postpartum employment increased. This paper examines the relationship between these trends from 1968-86 using data from the National Surveys of Family Growth. I find that these trends result from increases in the likelihood that a woman engages in both breastfeeding and postpartum employment. There has been an increase over time in the incidence and duration of women concurrently breastfeeding and working. However, the majority of employed women did not concurrently breastfeed, suggesting that conflicts between these behaviors still exist.

Temperature control and light penetration in a feedback interstitial laser thermotherapy system

The aim of this study was to describe the performance of a closed loop interstitial laser thermotherapy system in processed liver and to demonstrate its suitability for treating a vascularized tumour in vivo. The thermotherapy system consisted of an Nd: YAG laser and a temperature feedback circuit including an automatic thermometry system and thermistor probes. Experiments in processed liver were performed with a sapphire probe and temperature control at a distance of 10 mm. In most experiments at 1-2 W, and in half of the experiments at 3 W, there was no carbonization, a moderate change in the light penetration and excellent control of the temperature. In experiments with output powers of 4-5 W there was carbonization with rapid deterioration of light penetration and impaired control of the temperature. Carbonization affected the distribution of temperatures, which were lower below, and higher above, the laser tip in experiments with carbonization as compared to experiments without carbonization. Treatment of an adenocarcinoma implanted into rat liver was performed at 2 W with a bare fibre and without blood inflow occlusion. The feedback thermistor probe was placed 3 mm outside the margin of the tumour (largest diameter 9.5 +/- 0.3 mm (mean +/- SEM)). Temperature control and light penetration characteristics were similar to those found in vitro. No tumour could be demonstrated at sacrifice 6 days later. It is concluded that a closed loop feedback system can produce stable and reproducible local hyperthermia, that it performs better when carbonization is avoided and light penetration is preserved and that it has a great potential for interstitial thermotherapy of malignant tumours.

Nondisplaced and minimally displaced fractures of the lateral humeral condyle in children: a prospective radiographic investigation of fracture stability

Subsequent displacement of nondisplaced or minimally displaced fractures of the lateral humeral condyle while immobilized in plaster may contribute to severe complications. The possibility of assessing the stability of such fractures may be a help in planning the initial treatment. Our prospective investigation of 112 children aged 1-11 years aimed at describing radiographic criteria for prognosticating the stability of the fractures. According to the radiographic findings, the fractures were allocated to one of three groups representing stable fractures, fractures with undefinable risk, and fractures with high risk of later displacement. All children were treated with splinting only. Sixty-five fractures were classified as stable and turned out to be so without exception. Displacement occurred in six of 35 (17%) of the fractures judged uncertain and in five of 12 (42%) of those judged unstable. The subsequent displacement was 1 or 2 mm, and in one case, 3 mm. The defined criteria were found to be efficient in separating the stable and the high-risk fractures with acceptable confidence. The group of fractures with undecided risk of subsequent displacement was fairly large--one third of the total material. The implication the findings may bear to the treatment strategy of fractures is analyzed in a work in progress.

Efficacy of topical cooling in lung preservation: is a reappraisal due?

The aim of the present study was to test the efficacy of topical cooling as the only viable lung preservation method using the most challenging evaluation method, namely single-lung transplantation followed by immediate contralateral pneumonectomy. Ten domestic pigs (5 donors and 5 recipients) with a mean body weight of 57 kg (range, 53 to 59 kg) were used. After we administered systemic heparin (4 mg/kg), the lungs were harvested and placed in an atelectatic state under cold (8 degrees to 9 degrees C) low-potassium-dextran solution for 12 hours. Left lung transplantation was then done in the recipient pig followed by right pneumonectomy, thus making the recipient 100% dependent on the transplanted donor lung. No operative mortality or morbidity occurred. All animals were in excellent condition throughout the 24-hour observation period. They had normal blood gases which did not differ significantly from the preoperative blood gases obtained from the 5 recipients before transplantation (ie, when they had their own two lungs). A moderate increase (p < 0.05) in pulmonary vascular resistance was seen as compared with sham-operated animals. To conclude, topical cooling to 8 degrees C provides excellent lung preservation for 12 hours in pigs. If similar results can be obtained with other species, the currently accepted 6-hour limit for safe clinical lung preservation may be extended to 12 hours. It seems also warranted to critically reconsider which factors, apart from cooling alone, actually contribute favorably to 12-hour lung preservation.

Nitric oxide gives maximal response after coronary artery bypass surgery

The dose-response to inhalation of nitric oxide (NO) after coronary artery bypass surgery was studied in seven patients with normal preoperative lung function and chest radiograms. During postoperative controlled ventilation with PEEP 5 and 10 cmH2O, the patients inhaled NO in concentrations of 2 to 25 ppm, in random order, for 6 to 10 minutes. Hemodynamic and oximetric data were analyzed before, 5 minutes after start of the NO inhalation, and 5 minutes after the cessation. The response was the same at all concentrations; mean pulmonary artery pressure decreased by 11 +/- 1% (P < 0.05) and pulmonary vascular resistance decreased by 22 +/- 2% (P < 0.05). Systemic hemodynamics did not change, but oximetric parameters tended to improve. Changes in PEEP did not affect the response. It is concluded that, in patients who have undergone coronary artery bypass grafting, inhalation of 2 to 25 ppm NO causes a dose-independent decrease in pulmonary artery pressure and pulmonary vascular resistance. In order to investigate the dose-response curve, concentrations lower than 2 ppm of NO must be used.