Simultaneously recorded single-exhalation profiles of ethanol, water vapour and CO(2) in humans: impact of pharmacokinetic phases on ethanol airway exchange

The breath alcohol concentration (BrAC) standardized to the alveolar water vapour concentration has been shown to closely predict the arterial blood alcohol (ethanol) concentration (ABAC). However, a transient increase in the ABAC/BrAC ratio has been noted, when alcohol is absorbed from the gastrointestinal tract (absorption phase) and the ABAC rapidly rises. We analysed the plot of simultaneously recorded alcohol, water vapour and CO(2) against exhaled volume (volumetric expirogram) for respiratory dead space volume (VD), cumulative gas output and phase III slope within one breath to evaluate whether changes in the BrAC profile could explain this variability. Eight healthy subjects performed exhalations through pre-heated non-restrictive mouthpieces and the concentrations were measured by infrared absorption. In the absorption phase, the respiratory VD of alcohol was transiently increased and the exhaled alcohol was displaced to the latter part of the expirogram. In the post-absorption phase, the respiratory VD for alcohol and water vapour was stable and always less than the respiratory VD for CO(2), indicating that the first part of the exhaled alcohol and water originated from the conducting airway. The position of the BrAC profile between water vapour and CO(2) in the post-absorptive phase indicates an interaction within the conducting airway, probably including a deposition of alcohol onto the mucosa during exhalation. We conclude that the increase in the ABAC/BrAC ratio during the absorption phase of alcohol coincides with a transient increase in respiratory VD of alcohol and a delay in the appearance of alcohol in the exhaled air as the exhalation proceeds compared with the post-absorption phase.

Is cartilage sGAG content related to early changes in cartilage disease? Implications for interpretation of dGEMRIC

OBJECTIVE

This study investigates sulphated glycosaminoglycans (sGAG) content changes in early osteoarthritis (OA), and whether contrast-enhanced magnetic resonance imaging (MRI) of cartilage in vitro may identify early event of OA pathology.

METHOD

Osteochondral plugs from patients with hip OA or femoral neck fracture (reference group) were collected and analysed by 1.5 T MRI with ΔR1 as a measure of cartilage contrast concentration. Cartilage hydration, contents of sGAG, cartilage oligomeric matrix protein (COMP), hydroxyproline, denatured collagen, and aggrecan TEGE(392) neoepitope were determined and histological grading was performed.

RESULTS

sGAG content correlated to ΔR1, although no difference in either of these parameters was detectable between OA and reference cartilage at 4 h of contrast equilibration. In contrast, biochemical analysis of other cartilage matrix constituents showed distinct alterations typical for early cartilage degradation in OA cartilage and with clear evidence for increased aggrecan turnover.

CONCLUSION

In the present in vitro study, cartilage sGAG content could not distinguish between early OA cartilage and reference cartilage. Given, that delayed gadolinium enhanced MRI of cartilage (dGEMRIC) indicates early events in the pathogenesis of OA in vivo, our results from the in vitro studies imply other, additional factors than cartilage sGAG content, e.g., alterations in diffusion or increased supply of contrast agent in the diseased joint. Alternatively, an altered dGEMRIC reflects later stages of OA, when sGAG content decreases. Further investigations are warranted, to understand variations in sGAG content in pathology, an essential background for interpreting dGEMRIC measurements.

The use of propofol sedation in a paediatric intensive care unit

BACKGROUND

The aim of this study was to prospectively evaluate and report the experience of the use of continuous intravenous propofol sedation in a paediatric intensive care unit (PICU).

METHODS

All children younger than 16 years who were admitted to the PICU at a University Hospital for slightly more than a year and received propofol infusion were included prospectively and data were recorded before and within 6 h after completion of the propofol infusion.

RESULTS

A total of 174 out of 955 children (18·2%) received propofol infusion for sedation. The median age was 2 years 10 months (range: 2 months to 16 years), duration of propofol infusion 13 h (range: 1·6-179 h) and dose of propofol 2·9 mg/kg/h (range: 0·3-6·5 mg/kg/h). No one developed signs of the propofol infusion syndrome (PRIS). Neither dose >3 mg/kg/h, duration of infusion >48 h nor both were found to be related to adverse metabolic derangements or circulatory failure. Eight children increased their lactate concentration ≥1·8 mmol/L during propofol infusion. All had a favourable outcome. One child who had received propofol infusion for 10 h died, but this occurred 14 h after the infusion ceased and was without doubt attributed to a multiple organ failure not related to the propofol infusion.

CONCLUSION

Propofol infusion was used in this population at low risk of PRIS with no metabolic or circulatory adverse effects. These findings indicate that the occurrence of adverse effects may not be directly related to dose or duration of infusion, but emphasizes the risk that sporadic factors may be involved, such as genetic mutations. Guidelines are presented.

Breath alcohol analysis incorporating standardization to water vapour is as precise as blood alcohol analysis

A novel breath-alcohol analyzer based on the standardization of the breath alcohol concentration (BrAC) to the alveolar-air water vapour concentration has been developed and evaluated. The present study compares results with this particular breath analyzer with arterial blood alcohol concentrations (ABAC), the most relevant quantitative measure of brain alcohol exposure. The precision of analysis of alcohol in arterial blood and breath were determined as well as the agreement between ABAC and BrAC over time post-dosing. Twelve healthy volunteers were administered 0.6g alcohol/kg bodyweight via an orogastric tube. Duplicate breath and arterial blood samples were obtained simultaneously during the absorption, distribution and elimination phases of the alcohol metabolism with particular emphasis on the absorption phase. The precision of the breath analyzer was similar to the determination of blood alcohol concentration by headspace gas chromatography (CV 2.40 vs. 2.38%, p=0.43). The ABAC/BrAC ratio stabilized 30min post-dosing (2089±99; mean±SD). Before this the BrAC tended to underestimate the coexisting ABAC. In conclusion, breath alcohol analysis utilizing standardization of alcohol to water vapour was as precise as blood alcohol analysis, the present "gold standard" method. The BrAC reliably predicted the coexisting ABAC from 30min onwards after the intake of alcohol.

A community-based long-term follow up of women undergoing obstetric fistula repair in rural Ethiopia

OBJECTIVES

To assess urinary and reproductive health and quality of life following surgical repair of obstetric fistula.

DESIGN

Follow-up study.

SETTING

A newly established fistula clinic (2004) at Gimbie Adventist Hospital, a 71-bedded district general hospital in West Wollega Zone, in rural Western Ethiopia.

POPULATION

Thirty-eight women (86%) of 44 who had undergone fistula repair were identified in their community.

METHODS

Community-based structured interviews 14-28 months following fistula repair, using a customised questionnaire addressing urinary health, reproductive health and quality of life.

MAIN OUTCOME MEASURES

Urinary health at follow up was assessed as completely dry, stress or urge incontinence, or fistula. King's Health Questionnaire was modified and used for the quality-of-life assessment.

RESULTS

At follow up, 21 women (57%) were completely dry, 13 (35%) suffered from stress or urge incontinence and three (8%) had a persistent fistula. Surgery improved quality of life and facilitated social reintegration to a level comparable to that experienced before fistula development for both women who were dry and those with residual incontinence (P = 0.001). For women still suffering from fistula no change was seen (P = 0.1). Four women became pregnant following their surgery, among which there was one maternal death, three stillbirths and one re-occurrence of fistula.

CONCLUSION

Community-based, long-term follow up after fistula repair succeeded in Western rural Ethiopia. Despite one-third still suffering stress or urge incontinence, the women reported improved quality of life and social reintegration after fistula closure.

Ethnicity, socio-economic status and self-harm in Swedish youth: a national cohort study

BACKGROUND

Previous studies have shown an elevated risk for self-harm in adolescents from ethnic minorities. However, potential contributions to this risk from socio-economic factors have rarely been addressed. The main aim of this article was to investigate any such effects.

METHOD

A national cohort of 1009 157 children born during 1973-1982 was followed prospectively from 1991 to 2002 in Swedish national registers. Multivariate Cox analyses of proportional hazards were used to estimate the relative risk of hospital admission for self-harm. Parental country/region of birth was used as proxy for ethnicity.

RESULTS

Youth with two parents born outside Sweden (except those from Southern Europe) had higher age- and gender-adjusted hazard ratios (HRs) of self-harm than the majority population (HR 1.6-2.3). The HRs decreased for all immigrant groups when socio-economic factors were accounted for but remained significantly higher for immigrants from Finland and Western countries and for youth with one Swedish-born and one foreign-born parent.

CONCLUSIONS

Socio-economic factors explain much of the variation by parental country of birth of hospital admissions for self-harm in youth in Sweden.

Diagnosis of bacterial kidney disease by detection of Renibacterium salmoninarum by real-time PCR

Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum (Rs), is a serious threat to salmon in aquaculture as well as to wild populations. We have developed a real-time polymerase chain reaction (PCR) for detection of Rs in kidney samples. The PCR is based on detection of unique parts of the 16S rRNA gene of Rs and DNA equivalent to 1-10 Rs genomes was detected per reaction. No cross-reactivity with other fish pathogenic or related bacteria could be demonstrated. Analysis of individual kidney samples collected from BKD classified populations identified 39.9% of the fish as positive by real-time PCR compared with 28.0% by polyclonal enzyme-linked immunosorbent assay (ELISA). The real-time PCR assay was found to be well suited for complementary use with ELISA for diagnosis of BKD, with the ability to detect clinical as well as covert Rs infections. The infection level determined by the polyclonal ELISA and by real-time PCR was significantly correlated.

Repetitive transcranial magnetic stimulation (rTMS) in combination with escitalopram in patients with treatment-resistant major depression: a double-blind, randomised, sham-controlled trial

BACKGROUND

The role of high-frequency rTMS over the left cortex as an add-on strategy in the treatment of major depression is still uncertain even in patients resistant to pharmacotherapy. We had planned a large sham TMS controlled study in the acute phase with a placebo-controlled relapse-prevention phase with escitalopram. However, because a recent meta-analysis showed only a small effect size of rTMS over sham TMS in the acute treatment phase of depressed patients, we decided to make an interim analysis.

METHOD

In patients with medication-resistant major depression we administered in a randomised trial 15 sessions of sham-controlled rTMS over three weeks in combination with 20 mg escitalopram daily. After the last rTMS, the patients were followed for another 9 weeks on 20 mg escitalopram daily. The antidepressant effect was measured by the HAM-D(6) as primary outcome scale.

RESULTS

A total of 45 patients with complete data were randomised so that 23 patients received sham TMS and 22 patients received active, high-frequency rTMS over the left cortex. Over the 3 weeks, the active rTMS treatment was superior to sham TMS with effect sizes on the HAM-D(6) above 0.70, which indicates not only a statistically but also a clinically significant effect. The patients had typically been through two failed antidepressant treatment attempts with non-tricyclics before inclusion in the study. Both the rTMS and escitalopram were well-tolerated.

CONCLUSION

High-frequency rTMS over the left cortex is an add-on strategy of clinical significance in combination with escitalopram in patients with major depression resistant to non-tricyclic antidepressants.

Breath alcohol concentration determined with a new analyzer using free exhalation predicts almost precisely the arterial blood alcohol concentration

A new breath alcohol (ethanol) analyzer has been developed, which allows free exhalation, standardizes measured exhaled alcohol concentration to fully saturated water vapor at a body temperature of 37 degrees C (43.95 mg/L) and includes a built-in self-calibration system. We evaluated the performance of this instrument by comparing standardized alcohol concentration in freely expired breath (BrAC) with arterial (ABAC) and venous (VBAC) blood alcohol concentrations in fifteen healthy volunteers who drank 0.6 g of alcohol per kg body weight. The precision (coefficient of variation, CV) of the analyzer based on in vivo duplicate measurements in all phases of the alcohol metabolism was 1.7%. The ABAC/BrAC ratio was 2251+/-46 (mean+/-S.D.) in the post-absorptive phase and the mean bias between ABAC and BrAC x 2251 was 0.0035 g/L with 95% limits of agreement of 0.033 and -0.026. The ABAC and BrAC x 2251 were highly correlated (r=0.998, p<0.001) and the regression relationship was ABAC = 0.00045 + 1.0069 x (BrAC x 2251) indicating excellent agreement and no fixed or proportional bias. In the absorption phase, ABAC exceeded BrAC x 2251 by at most 0.04+/-0.03 g/L when tests were made at 10 min post-dosing (p<0.05). The VBAC/BrAC ratio never stabilized and varied continuously between 1834 and 3259. There was a proportional bias between VBAC and BrAC x 2251 (ABAC) in the post-absorptive phase (p<0.001). The pharmacokinetic analysis of the elimination rates of alcohol and times to zero BAC confirmed that BrAC x 2251 and ABAC agreed very well with each other, but not with VBAC (p<0.001). We conclude that this new breath analyzer using free exhalation has a high precision for in vivo testing. The BrAC reflects very accurately ABAC in the post-absorption phase and substantially well in the absorption phase and thereby reflects the concentration of alcohol reaching the brain. Our findings highlight the magnitude of arterio-venous differences in alcohol concentration and support the use of breath alcohol analyzers as a stand-alone test for medical and legal purposes.

Birth outcomes and pregnancy complications in women with a history of anorexia nervosa

OBJECTIVE

To examine birth outcomes and pregnancy complications in women with a history of anorexia nervosa.

DESIGN

Prospective cohort study.

SETTING

Nationwide study in Sweden.

POPULATION

All primiparous women--discharged from hospital with a diagnosis of anorexia nervosa during 1973 to 1996--who gave birth during 1983 to 2002 (n = 1000) were compared with all non-anorexia nervosa primiparous women who gave birth during the same years (n = 827,582).

METHOD

Register study with data from Medical Birth Registry and National Patient Discharge Register.

MAIN OUTCOME MEASURES

Pre-eclampsia, instrumental delivery, prematurity, small for gestational age, birthweight, Apgar score and perinatal mortality.

RESULTS

Main birth outcome measures in women with a history of anorexia nervosa were very similar to the main population. The only observed differences were a slightly lower mean birthweight and lower adjusted odds ratios for instrumental delivery in the anorexia nervosa group compared with the main population. Neither severity of the disease nor a shorter recovery phase after first hospitalisation was related to pregnancy complications or birth outcomes.

CONCLUSION

A history of anorexia nervosa was not associated with negative birth outcomes. Thus, special obstetric monitoring of pregnant women with history of anorexia nervosa does not seem to be warranted in a country with a satisfactory maternity surveillance.

Magnitude and Time-Course of Arterio-Venous Differences in Blood-Alcohol Concentration in Healthy Men

BACKGROUND AND OBJECTIVE

Human studies of arterio-venous (AV) differences in drug concentrations and the consequences for pharmacokinetic modelling and concentration-effect relationships are very limited. We therefore investigated the intravenous and intra-arterial concentrations of alcohol (ethanol) during the absorption, distribution and elimination stages of alcohol metabolism in healthy men.

STUDY PARTICIPANTS AND METHODS

Nine male volunteers aged 26-67 years drank 0.6 g alcohol/kg bodyweight in 2-15 minutes. The drink was prepared from 95% v/v alcohol, which was diluted with an alcohol-free beverage to 20% v/v. Before the start of drinking and for 6-7 hours post-administration, blood samples were drawn at 15- to 20-minute intervals from indwelling catheters in a radial artery and a cubital vein on the same arm. The blood-alcohol concentration (BAC) was determined by headspace gas chromatography, and blood-water content was measured by desiccation.

RESULTS

The peak concentration (Cmax) of alcohol in arterial blood was 0.98 g/L (SD 0.209) compared with 0.84 g/L (SD 0.176) for venous blood (p < 0.001), whereas median time to reach Cmax (tmax) was the same (35 minutes). The AV difference was greatest at 10 minutes after the end of drinking (mean 0.20 g/L [range 0.09-0.40 g/L]), decreasing as the absorption of alcohol continued. At a median time of 90 minutes post-administration (range 45-105 minutes), the AV difference was momentarily zero. At later times, the AV differences became increasingly negative and at 280 minutes post-administration the mean was -0.051 g/L (range -0.025 to -0.078 g/L). The slope of the post-absorptive phase (k0) was 0.116 g/L/h (SD 0.0167) for arterial blood compared with 0.109 g/L/h (SD 0.0185) for venous blood (p < 0.001). The extrapolated time to reach zero BAC was 391 minutes (SD 34) for arterial blood and 420 minutes (SD 41) for venous blood; the difference of 29 minutes was statistically highly significant (p < 0.001). The apparent volume of distribution of alcohol, the area under the concentration-time curves (AUC) and the water content of arterial and venous blood samples were not significantly different for the two sampling compartments.

CONCLUSION

The arterial and venous blood-alcohol profiles were shifted in time owing to the time it takes for alcohol to equilibrate between arterial blood and tissue water. Alcohol is metabolised in the liver but not in muscle tissue, which acts as a reservoir for alcohol. The concentrations of alcohol in arterial and venous blood were the same at only one timepoint, which signifies complete equilibration of alcohol in total body water. During the entire post-absorptive phase, the concentration of alcohol in venous blood draining skeletal muscles was slightly greater than the arterial blood concentration; therefore, the AV differences were negative.

Effects of dexamethasone on clinical course, C-reactive protein, S100B protein and von Willebrand factor antigen after paediatric cardiac surgery

BACKGROUND

Anti-inflammatory treatment with glucocorticoids during cardiopulmonary bypass can reduce inflammatory mediator release, but the effects of glucocorticoid on outcome are controversial.

METHODS

We studied the effects of dexamethasone on clinical course, C-reactive protein, von Willebrand factor antigen (vWf:Ag) and S100B in a randomized masked study of children after open cardiac surgery. Twenty children weighing >10 kg received dexamethasone (1 mg kg(-1)) and 20 controls received saline after induction of anaesthesia. We measured vWf:Ag as a marker of endothelial activation, S100B as a marker of cerebral protein release and C-reactive protein as a marker of inflammatory activity. Oxygenation, body temperature, fluid balance, leucocyte and platelet counts, days in the intensive care unit (ICU) and days on mechanical ventilation were noted.

RESULTS

Dexamethasone decreased C-reactive protein concentration on the first postoperative day (P<0.05), but did not affect the release of vWf:Ag or S100B. There was no significant difference in oxygenation, body temperature, fluid balance, leucocyte and platelet counts, days in the ICU or days on mechanical ventilation between the placebo and dexamethasone-treated groups.

CONCLUSION

Administration of dexamethasone before cardiopulmonary bypass for paediatric cardiac surgery decreased the inflammatory response, but did not affect the immediate features after surgery or changes in vWf:Ag or S100B.

Human-animal interactions and animal welfare in conventionally and pen-housed rats

The main aim of the present study was to explore the significance of large group/greater pen housing (PH) versus standard Makrolon caging (ST) in three behaviour tests related to human-animal interactions in the adult male laboratory rat. The rats' perception of human interaction was tested in three behavioural tests, of which two reflected common practical procedures, capture and restraint, whereas the third was a human approach test in a Y-maze. The rats' anticipatory reactions to handling and the reactions to restraint did not differ between groups, but the ST rats approached a human hand more quickly than did the PH rats (P < 0.01). Although food intake did not differ, ST rats gained more weight (P < 0.01) and had higher total cholesterol values (P < 0.01) than PH rats. In conclusion, this study shows that housing rats in large groups in an enriched environment did not influence their anticipatory reaction to handling in normal handling situations. However, as the PH rats tended to have a longer approach latency than ST rats in the Y-maze there might be underlying differences in appraisal that are not detected in practical situations. In addition, the PH rats weighed less and had lower total cholesterol values than ST rats and their urine corticosterone values were higher. These effects are suggested to be due to higher physical activity in the PH rats, and the implications of this on the animal as a model is discussed.

How common is severe pulmonary hypertension after pediatric cardiac surgery?

BACKGROUND

Pulmonary hypertension may result in significant morbidity and mortality after pediatric cardiac surgery. The objective of this study was to determine the incidence and outcome of severe pulmonary hypertension, defined as a ratio of pulmonary to systemic arterial pressure equal to or greater than 1.0, after cardiac surgery in children.

METHODS

Data from all children younger than 18 years who had undergone cardiothoracic surgery from January 1, 1994, to December 31, 1998, were examined. To find children with severe pulmonary hypertension, we reviewed intensive care unit charts from patients who had been monitored with a pulmonary artery catheter after the operation (n = 151), had received mechanical ventilation for more than 4 days after the operation (n = 124), or had died in the operating room or the intensive care unit (n = 22). Intraoperative and postoperative measurements of mean pulmonary arterial pressure and postoperative echocardiographic studies during the first 3 postoperative days were used to select the children.

RESULTS

During the study period, 1349 children (including 164 neonates and 511 infants, median age 12 months) underwent cardiac operations with an overall perioperative mortality of 22 patients (1.6%). Twenty-seven children (2%, median age 4.2 months) had severe pulmonary hypertension. Of these, 2 (7.4%) died within 30 days of the operation, and 3 others (11%) died within a year (median follow-up 53 months). Nitric oxide inhalation was used in 5 of the 27 cases, and it probably saved the life of 1 patient, may have helped in 1 case, and had no discernible effect in 3 cases. Severe pulmonary hypertension was most common after correction of complete atrioventricular septal defects (14%, n = 12/85). Thirteen of 131 children with Down syndrome (9.9%) had severe pulmonary hypertension.

CONCLUSION

Severe postoperative pulmonary hypertension occurred after 2% of the cardiac procedures and in most cases was managed successfully with conventional treatment and had a favorable postoperative outcome. The low incidence relative to previous reports may reflect the benefits of early correction and improved intraoperative and postoperative care.

Mechanical impedance of the human body in vertical direction

The mechanical impedance of the human body in sitting posture and vertical direction was measured during different experimental conditions, such as vibration level (0.5-1.4 m/s2), frequency (2-100 Hz), body weight (57-92 kg), relaxed and erect upper body posture. The outcome shows that impedance increases with frequency up to a peak at about 5 Hz after which it decreases in a complex manner which includes two additional peaks. The frequency at which the first and second impedance peak occurs decreases with higher vibration level. Erect, compared with relaxed body posture resulted in higher impedance magnitudes and with peaks located at somewhat higher frequencies. Heavy persons show higher impedance magnitudes and peaks at lower frequencies.

Performance of Uricult Trio assessed by a comparison method and external control panels in primary healthcare

Using the comparison method, we have evaluated the technical performance of Uricult Trio by culturing on Uricult Trio and agar plates. Urine samples (477) from patients in primary healthcare were cultured in parallel in a microbiology laboratory. The result for Uricult Trio evaluated using the comparison method was incorrect in 32% of the cultures. We also studied the performance of Uricult Trio when used in primary healthcare by using external control panels. External control panels consisting of Uricult Trio, inoculated with known concentrations of certain bacterial strains, were used to assess the performance of Uricult Trio in primary healthcare during the period 1993-7. Aberrations in reports of concentration have ranged from 10% to 33%, failure in reporting of mixed culture from 0% to 91% and reporting of E. coli from 15% to 86%. There has been no sign of improvement over the years. The results indicate that Uricult Trio is unsuitable for indications other than exclusion of urinary tract infection or diagnosis of urinary tract infection caused by E. coli. Further, there is need for quality assurance and training activities at primary healthcare laboratories, probably best carried out in collaboration with local clinical microbiology laboratories.

Fat infiltration in liver and activity of lecithin:cholesterol acyltransferase in serum of dry and lactating dairy cows

To study the relationship between fat infiltration in the liver and the decrease in the activity of serum lecithin:cholesterol acyltransferase (LCAT), blood and liver samples were taken from 14 multiparous (MP) and 16 primiparous (PP) dairy cows four weeks and one week before, and one, four and eight weeks after calving. During the dry period, half the animals received a protein supplement. LCAT activity decreased significantly in all groups before parturition, but returned to the initial level within 1-4 weeks after parturition. There were no differences between the feeding groups, but after calving, the LCAT activity in the MP cows was significantly lower than in the PP cows. Fat infiltration was not detected in the PP cows, and in the MP cows fat infiltration was mild and fell within the physiological range. There was no correlation between liver fat content and the activity of LCAT in serum. These results suggest that shortly before and after parturition, the activity of LCAT in serum is limited by post-transcriptional regulation, possibly by the availability of amino acid for export protein synthesis in the liver.

The effects of epinephrine/norepinephrine on end-tidal carbon dioxide concentration, coronary perfusion pressure and pulmonary arterial blood flow during cardiopulmonary resuscitation

End-tidal CO2 concentration correlates with pulmonary blood flow during cardiopulmonary resuscitation and has been claimed to be a useful tool to judge the effectiveness of chest compression. A high concentration of end-tidal CO2 has been related to a better outcome. However, most authors have noticed a decrease in end-tidal CO2 concentration after administration of epinephrine, concomitant with an increase in coronary perfusion pressure and an increased incidence of return of spontaneous circulation. This study was performed to evaluate changes in end-tidal CO2 concentration after injection of vasopressors during cardiopulmonary resuscitation and to investigate the time-course of the response and possible explanations for it. After 1 min of electrically induced cardiac arrest and 5 min of chest compressions, 18 pigs were randomly assigned to receive 0.045 mg kg(-1) epinephrine, 0.045 mg kg(-1) norepinephrine or no drug. After another 4 min of chest compressions the pigs were defibrillated. End-tidal CO2, pulmonary blood flow and coronary perfusion pressure decreased immediately after the induction of cardiac arrest, increased slightly during chest compressions and increased initially to supernormal levels after the return of spontaneous circulation. Injection of epinephrine or norepinephrine during chest compressions decreased end-tidal CO2 51 +/- 2%, (mean +/- S.E.M.), and 43 +/- 1%, respectively, and pulmonary blood flow by 134 +/- 13 and 125 +/- 16%, respectively, within 1 min, simultaneously increasing coronary perfusion pressure from 10 +/- 2 to 45 +/- 5 mm Hg and from 11 +/- 1 to 38 +/- 5 mm Hg, respectively. The coronary perfusion pressure slowly fell, but the effects on end-tidal CO2 and pulmonary blood flow were prolonged. In conclusion, vasopressors increased coronary perfusion pressure and the likelihood of a return of spontaneous circulation, but decreased end-tidal CO2 concentration and induced a critical deterioration in cardiac output and thus oxygen delivery in this model of cardiopulmonary resuscitation.

Effects of rhBMP-2 and osteopromotive membranes on experimental bone grafting

A problem with using autogeneic bone for onlay grafting is its degree of incorporation and volumetric persistence. This study explored whether improved graft volumetric maintenance can be achieved by recombinant human bone morphogenetic protein-2 (rhBMP-2) and whether a combination of rhBMP-2 and osteopromotive membranes is advantageous in this respect. Unicortico-cancellous bone grafts were positioned below the temporal muscle bilaterally in 48 adult Lewis rats. The recipient bone was ground, and the grafted area was randomly treated according to one of eight different alternatives. Two doses of rhBMP-2 (4 microg/80 microl or 32 microg/80 microl buffer) in a collagenous carrier were tested, with or without coverage with expanded polytetrafluoroethylene membranes. As controls, membrane and carrier, alone or in combination, and onlay grafts only were used. The results were evaluated after 4 and 20 weeks by routine histologic examination and immunohistochemical labeling for various bone and cartilage matrix proteins. After 4 weeks, rhBMP-2-treated grafts showed complete integration, whereas for controls, only the membrane-alone group attained incorporation after 20 weeks. The combined treatment with high-dose rhBMP-2 and membrane demonstrated, as compared with the remaining rhBMP-2 groups, pronounced bone formation and less graft resorption, resulting in maintained or increased graft size. This was observed after 4 weeks, and the result remained at 20 weeks. Treatment with high-dose rhBMP-2 without membrane placement, in contrast, resulted in extensive resorption and graft size reduction at 20 weeks. Control groups showed less success in graft size persistence. It was concluded that a combination of high-dose rhBMP-2 and osteopromotive membranes had a synergistic effect, leading to rapid, complete graft integration and size maintenance. In the absence of a membrane, the protein seemed to accelerate the remodeling of the graft.