Evaluation of results derived from the analysis of certified reference materials--a user-friendly approach based on simplicity

Certified reference materials (CRMs) have now been in regular use for several decades. Their production and certification are regulated by international standards. But, even today there are no agreements on procedures for evaluating results obtained by the users. As a consequence, the way CRM results are treated in the literature leaves a lot to be desired. A statistical evaluation is rarely, if ever, described in published reports. The most common approach is to compare the found mean and/or range with the certified range and then state if the mean falls within the certified range, or if the two ranges overlap. If this happens, the analyst is usually satisfied. In addition, usually no regard is paid to the fact that the certified interval is based on a 95% confidence interval (CI) and the found interval on standard deviation and that this evaluation has little, if any, statistical relevance. Long-term evaluation of a CRM often consists in nothing more than producing a control chart, which relates the found results to the certified mean and CI. This paper is an attempt to improve the situation by providing a set of easy-to-use guidelines for evaluating results from CRMs. During the process we have identified different areas in which there is a need for such guidelines: 1. short-term evaluation of a single, or multiple, determination at one or several specific times; 2. identification of systematic and random errors; 3. evaluation of CRMs when used in a collaborative trial of a method; and 4. long-term evaluation for monitoring an analytical process over extended periods of time. It is important that the guidelines do not require expert competence in statistics from the analyst. Such obstacles would probably render most guidelines unused.

[Anesthesia in extreme obesity]

BACKGROUND

Approximately 1-2% of all anesthetized patients are morbidly obese (body mass index > 35 kg/m2). The perioperative mortality is significantly elevated (up to 20%) compared with lean patients. Morbidly obese patients are at high risk for cardiopulmonary dysfunction. Difficult airway management is reported in 13-20% of obese patients. Hypoxia is often observed due to faster desaturation during induction of anesthesia. After surgery, patients are endangered by a high incidence of obstructive sleep apnea syndrome (50%), pulmonary atelectasis (5%) and acute pulmonary embolism (5-12%).

ANESTHESIA

Individualized perioperative management is required based on preoperative history and physical examination. Modern anesthetic drugs (desfluran, sevoflurane or propofol, and remifentanil, respectively) allow rapid recovery and early postoperative mobilization. Adequate monitoring, e.g. by an intraarterial blood pressure monitoring and repetitive blood gas analyses, improves patient safety prior the onset of complications.

POSTOPERATIVE MANAGEMENT

Postoperative admission on an intensive care unit of morbidly obese patients is based upon concomitant diseases and surgical requirements. The main reason for admission is an inadequate pulmonary gas exchange. This interdisciplinary approach will reduce the risk of anesthesia and avoid complications in morbidly obese patients.

[The impact of morbid obesity on the peri- and postoperative course after aortocoronary bypass surgery]

BACKGROUND AND OBJECTIVE

Excessive obesity is considered to be a risk factor in coronary bypass grafting. The aim of the current study was to examine if grossly overweight patients with a body mass index (BMI) > 35 suffer from higher morbidity and mortality when compared with patients with normal body weight (BMI = 20-25).

PATIENTS AND METHODS

206 extremely obese patients (group A) and 206 patients with normal body weight (group B) originating from a total of 5614 patients undergoing coronary bypass grafting in the time span between 1.4.1996-1.10.2000 were studied retrospectively and consecutively. The data were obtained from case histories, questionnaires and interviews. Statistical analysis was performed by the chi 2 test after Pearson, the t test and the Kaplan-Meier method depending on the statistical problem analysed using the SPSS software v. 8.0.

RESULTS

The comparison of group A with group B revealed a significantly higher incidence of diabetes mellitus (p < 0.001), hypertension (p < 0.001) and hyperlipidaemia (p < 0.01) in group A. The only significant differences regarding the surgical procedure were the longer operation time (212.3 +/- 44.6 min, mean +/- SD) and aortic cross-clamp time (53.8 +/- 17.4 min, mean +/- SD) in group A (p < 0.05). The duration of mechanical ventilation, the incidence of respiratory insufficiency and the stay in the intensive care unit were not significantly different. The disorders of wound healing both in the sternal and the graft removal regions occurred significantly more frequently in group A (p < 0.001). The 30 days mortality rate in group A (1.5%) was not significantly different from group B (p < 0.001). The 30 days mortality rate in group A (1.5%) was not significantly different from group B (2.9%). The follow-up analysis of the 30 days mortality rate in different age groups revealed no significant differences in patients aged between 60 and 75 years. The mean survival rate after 4 years was 87.2% in group A and 86.4% in group B.

CONCLUSION

In spite of higher morbidity our results did not reveal significantly higher mortality in extremely obese patients. After operation the patients considered their state improved, therefore elective coronary surgery in grossly overweight patients seems to be indicated also without previous weight reduction.

Quantitative evaluation of the performance of different electrical tomography devices

Two widely used electrical tomography systems, the Sheffield Mark I and the DAS-01P, were quantitatively evaluated and compared to the newly developed Goe-MF system. The performance was quantified using a hardware phantom which closely matches the real input and transfer impedances of the human thorax and allows measurements equivalent to different states of lung inflation. Our results demonstrate that adequate averaging is necessary for noise reduction for the Mark I and especially for the DAS-01P system to get meaningful results even in visualizing maximal respiratory manoeuvres. The Goe-MF system showed a notably improved signal-to-noise ratio which allows also dynamic measurements at low levels of lung volume changes, e.g., in intensive care lung injury patients.

Primary malignant fibrous histiocytoma of the lung: IGF-II producing tumor induces fasting hypoglycemia

Augmented glucose utilisation or secretion of insulin-like-growth-factor II (IGF-II) are discussed as important pathogenetic factors in tumor-associated hypoglycemia (Doege-Potter Syndrome) with suppressed insulin and C-peptide levels. Primary malignant fibrous histiocytoma of the lung is an uncommon neoplasia and its association with hypoglycemia is rare and the causal relationship remains unclear. - We report a 57-year-old male with spontaneous hypoglycemia (1.67 mmol/l) due to a primary malignant fibrous histiocytoma of the lung, secreting IGF-II. Insulin (0.10 nmol/l; normal range 0.33-1.2) and C-peptide (3.0 mIU/l; 5-25) levels were suppressed in combination with low levels of growth hormone (<0.5 ng/ml; <7 ng/ml) and IGF-I (<66.0 ng/ml; 70-246). The elevated IGF-II level (787 ng/ml; 300-500) and decreased IGF-binding protein 3 (1.6 mg/l; 2-5) indicated a high free IGF-II activity. After surgery (resection of the right upper lobe), glucose (4.4 mmol/l), insulin (9.0 mIU/L) and C-peptide (0.84 nmol/l) levels returned to normal. Serum IGF-I (289 ng/ml) and the IGF-I/IGF-II ratio (<0.08 preoperative vs. 0.41 postoperative; >0.20) increased to the normal reference range. - In conclusion, malignant fibrous histiocytoma (MFH) is rarely described presenting as tumor-induced hypoglycemia. Doege-Potter Syndrome in MFH seems to be related to tumor-associated IGF-II production.

Completion pneumonectomy: current indications, complications, and results

OBJECTIVE

Completion pneumonectomy is reported to be associated with high morbidity and mortality, especially when done in patients with benign disease. We review our 9 years of experience with this operation to evaluate the postoperative outcome and long-term results of various indications.

METHODS

Between January 1990 and December 1998, 66 consecutive patients underwent completion pneumonectomy (6.8% of all pneumonectomies), and their cases were retrospectively reviewed. The indication was benign disease in 17 patients and malignant disease in 49 patients. In patients with malignant indications there were 14 local recurrences, 4 second primary tumors, 5 metastatic diseases, and 26 indications because of incomplete initial resection.

RESULTS

There were no intraoperative deaths, and the postoperative mortality rate was 7.6%. Complications were encountered in 32 (53%) patients, without any significant difference between benign indication (71%) and malignant indication (47%; P =.0923). Bronchopleural fistula was encountered in 5 (7.6%) patients, and empyema was encountered in 7 (11%) patients. The actuarial 5-year survival was 57% for all patients, 65% for those with benign indications, and 54% for those with malignant indications (60% for local recurrence, 50% for second primary tumor, and 56% for incomplete resection), without any difference between benign and malignant indications (P =.9478).

CONCLUSIONS

Completion pneumonectomy can be performed with acceptable mortality and morbidity, even in patients with benign disease. Patients with preoperative infection can be managed with bronchial stump covering and adequate postoperative drainage. Although complications are common, they can successfully be managed with a proper understanding of them.

[Multiple myocardial revascularization on the beating heart: risks, benefits and outlooks]

INTRODUCTION

Avoidance of extracorporeal circulation during beating heart surgery (OP CAB = Off-Pump Coronary Artery Bypass Surgery) for aortocoronary bypass grafting (ACBG) is gaining increasing importance in modern cardiac surgery. With the development of new mechanical stabilization devices, the revascularization of the posterior wall of the heart and the distal right coronary artery became feasible. Especially high-risk patients with multiple risk factors for open heart surgery will profit from this approach, because the negative effects of the extracorporeal circulation are avoided.

METHODS

From 7/97 until 12/99 a total of 158 patients with multivessel-coronary artery disease were operated on the beating heart. In the same time course, a total of 2869 patients were operated conventionally using the extracorporeal circulation as a standard procedure.

RESULTS

Due to patient selection, the two groups differ in the preoperative data concerning previous neurologic deficits. None of the patients in the OP CAB group suffered a permanent neurologic deficit after the operation, whereas in the CAB group the rate of stroke was 1.3%. The rate of temporary neurologic deficits, such as TIA (temporary ischemic attack) or PRIND (prolonged reversible neurologic deficit), was higher in the OP CAB group due to patient selection. No surgcially associated aortic dissection was seen in the OP CAB group.

CONCLUSIONS

This and other studies have shown the effectiveness of OP CAB surgery concerning perioperative complications and survival rates. Especially high-risk patients with multiple risk factors for a cardiac operation profit from a beating-heart operation avoiding extracorporeal circulation. The question in how far the higher rate of reoccurring angina and the larger number of interventional treatments in OP CAB patients reported in the literature are due to the learning curve remains unanswered. Long-term studies will show whether the result of beating heart surgery is as good as the result of conventional "on-bypass" surgery.

[Aortic valve replacement in 80- and over 80-year-old patients. Short-term and long-term results]

Due to demographic changes in average life expectancy, the age of patients undergoing cardiac surgery is increasing as well. We have reviewed the short- and long-term outcome in patients over 80 years of age after aortic valve replacement. From 01 Jan 1995 until 31 Dec 1998, 105 patients (76 women, 29 men between 80 and 89 years, median: 83) underwent aortic valve replacement. 42% presented with aortic stenosis, 58% with combined valve disease with leading stenosis. 53% (group A) received isolated valve replacement, 47% (group B) underwent myocardial revascularization as well. The in-hospital mortality rate was 8.9% for group A and 14.3% for group B. The follow-up time ranged between 10 and 243 weeks (median: 112 weeks). None of the patients had to be reoperated for prosthetic valve dysfunction or endocarditis. Bleeding complications due to anticoagulant therapy were not observed. Of the 11 deaths during the follow-up period, 5 (45%) were cardiac in nature and 2 (18%) related to stroke. Actuarial survival rates for group A were 98, 95 and 88% at 1, 2 and 3 years, and for group B 92, 84 and 84%, respectively. Permanent nursing care was not required 1 year after the operation by 98% of patients in group A (2 years: 95%, 3 years: 88%) and by 100% of patients in group B (2 years: 95%, 3 years: 88%). At an interval of 1 year after the operation 98% of patients in group A had not been hospitalized as a result of cardiac disorders (2 years: 98%, 3 years: 94%). The rates for group B were 90, 82 and 82%. Compared with younger age groups, aortic valve replacement in patients 80 years of age and older is associated with a distinctly increased mortality and morbidity. However, our data suggest that considering the poor prognosis of conservative therapy of symptomatic aortic valve disease, the functional status as well as life expectancy in this age group seems to be positively influenced by aortic valve replacement.

[Multiple off pump coronary artery bypass grafting - risks and benefits]

INTRODUCTION

Avoidance of extracorporeal circulation during beating heart surgery (OP CAB = Off-Pump Coronary Artery Bypass Surgery) for aortocoronary bypass grafting (ACBG) is gaining increasing importance in modern cardiac surgery. With the development of new mechanical stabilization devices, the revascularization of the posterior wall of the heart and the distal rith coronary artery became feasable. Especially high-risk patients with multiple risk factors for open heart surgery will profit from this approach, because the negative effects of the extracorporeal circulation are avoided.

METHODS

From 7/97 until 12/99 a total of 158 patients with ultivessel-coronary artery disease were operated on the beating heart. In the same time course, a total of 2869 patients were operated conventionally using the extracorporeal circulation as a standard procedure.

RESULTS

Due to patient selection, the two groups differ in the preoperative data concerning previous neurologic deficits. None of the patients in th OP CAB group suffered a permanent neurologic deficit after the operation, whereas in the CAB group the rate of stroke was 1.3%. The rate of temporary neurologic deficits, such as TIA (temporary ischemic attack) or PRIND (prolonged reversible neurologic deficit), was higher in the OP CAB group due to patient selection. No surgially associated aortic dissection was seen in the OP CAB group.

CONCLUSIONS

This and other studies have shown the effectiveness of OP CAB surgery concerning perioperative complications and survival rates. Especially high-risk patients with multiple risk factors for a cardiac operation profit from a beating-heart operation avoiding extracorporeal circulation. The question in how far the higher rate of reoccuring angina and the larger number of interventional treatments in OP CAB patients reported in the literature are due to the learning curve remains unanswered. Long-term studies will show whether the result of beating heart surgery is as good as the result of conventional "on-bypass" surgery.

[Isolated coronary bypass operation in the 9th decade of life]

The average age of patients undergoing cardiac surgery has increased continuously during the last three decades due to a progressively increasing number of older people in the population and the advances in operative and perioperative treatment in open heart surgery. Consequently we have investigated the short- and long-term results of isolated myocardial revascularization in patients who are in their ninth decade of life. Between 1 January 1995 and 31 December 1998, 121 patients (51 women, 70 men, age 80 to 88 years, median: 82 years) underwent isolated coronary artery bypass grafting. As part of the revascularization, a unilateral internal mammary artery graft (IMA) was used in 87% of cases. The in-hospital mortality was 6.6%. Analysis of predictors of mortality unveiled the following factors: ejection fraction less than 50%; history of recent left ventricular failure; extent of coronary artery disease; perioperative use of an intraaortic balloon pump (IABP) and symptomatic pericardial effusion. Use of the IMA revealed no influence on in-hospital mortality. The median follow-up time was 20 months (range: 2-48 months). Survival rates after 1, 2, and 3 years were 93.1%, 87.3% and 73.7% for women and 86.9%, 82.5% and 65.1% for men. These survival rates were comparable with those of the entire 82 year old population. Predictors for late death were male gender, history of stroke, history of arterial embolism, and postoperative pulmonary failure resulting in mechanical ventilation. During the follow-up period myocardial infarcts were subsequently not observed. Freedom from angina after 1, 2 and 3 years was 90.1%, 82.6% and 78.1%, respectively. At an interval of 1 year after the operation 87.6% of patients had not been hospitalized as a result of cardiac disorders (2 years: 80.1%, 3 years: 73.2%). Permanent nursing care was not required 1 year after the operation by 94.3% of patients (2 years: 91.5%, 3 years: 91.5%). Four percent of the survivors suffered from permanent delirium, 3% from depression, 5% from lack of concentration, and 6% from vertigo. In summary this study has revealed that, in patients over eighty years of age suffering from ischemic heart disease, coronary artery bypass grafting has acceptable short- and long-term results. Yearly mortality rates during the first 3 years after the operation are comparable with the expected mortality rate in an age-matched population.

C-MYC expression in medulloblastoma and its prognostic value

To identify prognostic factors in medulloblastoma, a common malignant brain tumor of childhood, expression of the oncogene c-myc was examined at the mRNA level by in situ hybridization. c-myc mRNA expression was observed in 30 of 72 tumors (42%). The c-myc gene copy number was determined by quantitative PCR from genomic DNA of paraffin-embedded tumors. c-myc gene amplification was present in 5 of 62 cases (8.3%). Therefore, c-myc amplification was obviously not the cause of c-myc mRNA expression in most samples. Kaplan-Meier estimation revealed a significant correlation between c-myc mRNA expression and survival (total mean follow-up 4.6 +/- 3.6 years, log-rank p = 0.02). Multivariate logistic regression analysis including sex, age, histological type, degree of surgical resection and expression of synaptophysin, GFAP and c-myc, was carried out on 54 patients who received both radiotherapy and chemotherapy. The analysis identified expression of c-myc as an independent predictive factor of death from disease.

A simple method to check the dynamic performance of electrical impedance tomography systems

The test concept as well as the design of a simple resistor phantom suitable for the evaluation of the properties of electrical impedance tomographic (EIT) systems is presented. Input and transfer impedance of the phantom are matched with those of the human thorax. Amplitude of the local impedance variations similar to in vivo conditions (ventilation) can be intentionally set to perform measurements on different states. The theoretical potential differences between the electrodes are calculated. The evaluation procedure is performed in terms of the local amplitude of the relative impedance change as well as the local distribution of noise. The whole procedure can be applied either to compare quantitatively the performance of different EIT data acquisition systems or to determine the amount of measurement disturbance caused by the external electrical environment in clinical settings.

Optimizing deconvolution techniques by the application of the Münchhausen meta algorithm

A deconvolution applied to disturbed data often gives poor results, due to fundamental difficulties associated with ill-posed problems. Many numerical and theoretical methods have been invented to circumvent this phenomenon. Their performance varies, depending on the given problem and data. The main aim of this paper is to provide a decision rule for choosing a method for deconvolution and application of this method to the same data. We have called this meta-algorithm Münchhausen. In this paper we introduce and describe for the first time the basic principle of artificial disturbance of the data in the set-up of deconvolution. We demonstrate some interesting features of the random procedure Münchhausen, such as the non parametric set-up, robustness to disturbance of the data and last but not least good performance.

Simultaneous myocardial revascularization and aortic valve replacement: stentless versus stented bioprostheses

Implantation of stentless aortic valve prostheses is more time-consuming than implantation of conventional stented bioprostheses. Simultaneous myocardial revascularization can result in a considerably prolonged operation time. We reviewed our patients with regard to surgical aspects in the specific patient cohorts. From April 1996 to April 1999, 303 patients were operated for aortic valve disease with or without concomitant coronary artery revascularization. Mean age was 75 years, ranging between 36 and 90 years. Using the Medtronic Freestyle valve, the following techniques of implantation were used: subcoronary technique, 163 patients, 61.5%; root inclusion technique, 7 patients, 3.5%; total root replacement, 30 patients, 15%. Total hospital mortality rate was 5.6%, reflecting age and concomitant disease of these patients. For isolated aortic valve replacement, the mortality rate was 4.7% and 6.7% for combined procedures. Coronary artery patients who are not suitable for stentless valve implantation owing to extensive aortic root calcification have a higher perioperative mortality rate. Compared with the isolated valve replacement and despite more extensive surgery and prolonged operative time, simultaneous myocardial revascularization in patients with stentless prostheses implantation can be performed without an increased risk.

Low frequency of defective alleles of cytochrome P450 enzymes 2C19 and 2D6 in the Turkish population

BACKGROUND AND OBJECTIVES

The genetically polymorphic cytochrome P450 enzymes 2Cl9 (CYP2Cl9) and 2D6 (CYP2D6) contribute to the metabolism of about 30% of all drugs. For analysis of the ethnic-related differences in drug disposition and as a preparation for routine genotyping, we examined CYP2C19 and CYP2D6 mutations in a large Turkish population.

METHODS

CYP2C19 and CYP2D6 alleles were determined with use of genomic deoxyribonucleic acid from 404 unrelated Turkish individuals. CYP2C19 alleles *1 to *5 and CYP2D6 alleles *1 to *12, and *14, *15, and *17 were measured by polymerase chain reaction-restriction fragment length polymorphism assays.

RESULTS

From 404 subjects genotyped for CYP2C19, allele frequencies of CYP2C19*1 (wt), CYP2C19*2 (ml), and CYP2C19*3 (m2) were 0.88, 0.12, and 0.004, respectively; mutations m3 and m4 were not found. Four individuals (1.0%) were predicted to be poor metabolizers (CYP2C19*2/*2), a significantly lower frequency compared to Middle European populations. Among 404 subjects genotyped for CYP2D6, most frequent alleles were CYP2D6*1 (allele frequency 0.37), *2 (0.35), *4 (0.11), *10 (0.06), duplications *1x2, *2x2, or *4x2 (0.06), *5 (0.01), and *17(0.01). Overall, six subjects (1.49%) were predicted to be CYP2D6 poor metabolizers, and 35 subjects (8.66%) were predicted to be ultrarapid metabolizers as a result of CYP2D6 gene duplications.

CONCLUSION

Obviously, within Europe there is a north-south gradient, with decreasing frequency of poor metabolizers of CYP2C19 and CYP2D6 to the south and a corresponding increase of ultrarapid metabolizers of CYP2D6. As in other white groups, only CYP2C19*2 plays a relevant role for the CYP2C19 poor metabolizer phenotype. The mutational spectrum of CYP2D6 indicated partial ethnic relationships to Asian and African populations.

Simulation of the initial concentration-time course after intravenous application of the drug

In this paper we present a widely applicable computational method for the description of the initial concentration-time-course after intravenous injection of a substance. The intravascular concentration-time course, r, is described as r = c0 + g x r, where the asterisk denotes the convolution operation, c0 is the concentration-time course during the first passage of the substance and g is the transport function of the body. If the body transport function is known, then the concentration-time course of a substance can be predicted. The site of interest can be chosen arbitrarily, i.e. the concentration-time course in the arterial circulation supplying any organ can be described. This might be of special interest for the optimal design of intravenous injections of contrast media, where initial concentrations at the region of interest determine the success of the diagnostic procedure.

Errors of the backextrapolation method in determination of the blood volume

Backextrapolation is an empirical method to calculate the central volume of distribution (for example the blood volume). It is based on the compartment model, which says that after an injection the substance is distributed instantaneously in the central volume with no time delay. The occurrence of recirculation is not taken into account. The change of concentration with time of indocyanine green (ICG) was observed in an in vitro model, in which the volume was recirculating in 60 s and the clearance of the ICG could be varied. It was found that the higher the elimination of ICG, the higher was the error of the backextrapolation method. The theoretical consideration of Schröder et al (Biomed. Tech. 42 (1997) 7-11) was proved. If the injected substance is eliminated somewhere in the body (i.e. not by radioactive decay), the backextrapolation method produces large errors.

Phospholipase A2 activity in body fluids and pancreatic tissue in patients with acute necrotising pancreatitis

OBJECTIVE

To measure pancreatic and non-pancreatic phospholipase A2 activity in human acute necrotising pancreatitis.

DESIGN

Prospective study.

SETTING

University hospital, Finland.

SUBJECTS

20 patients with acute necrotising pancreatitis.

INTERVENTIONS

Serum and urine samples were taken daily for a week and fluid from peritoneal lavage for six days after admission. Samples from the pleural cavity were taken from patients in whom pleural drainage was considered necessary. Pancreatic tissue was recovered from the patients who were operated on for acute pancreatitis or for pancreatic tumour.

MAIN OUTCOME MEASURES

Serum phospholipase A2, amylase, and lipase activities.

RESULTS

Serum phospholipase A2 activity increased up to eightfold, 25.0 (5.4) IU/L (n = 20, range 9.0-77 IU/L) (reference value <3 IU/L) and remained high during the first week, whereas serum amylase and lipase returned to the reference range during the first four days. The maximal phospholipase A2 activity in urine was 4.5 IU/L, in the fluid from peritoneal lavage 16.9 IU/L, and in the fluid from the pleural cavity 37.0 IU/L. Phospholipase A2 activity in necrotic pancreatic tissue ranged from 0.25 to 5.70 IU/g and in normal pancreatic tissue from 9.85 to 15.0 IU/g. Preincubation at 60 degrees C showed non-pancreatic phospholipase A2 activity predominated in serum, whereas part of the enzyme activity in the fluids from pleural cavity and peritoneal lavage proved to be of pancreatic derivation.

CONCLUSIONS

The results suggest a role for both pancreatic and non-pancreatic phospholipase A2 in acute pancreatitis. Preincubation at 60 degrees C proved useful in the differentiation between pancreatic and non-pancreatic phospholipase A2 activity.

Electrical impedance tomography in monitoring experimental lung injury

OBJECTIVE

To apply electrical impedance tomography (EIT) and the new evaluation approach (the functional EIT) in monitoring the development of artificial lung injury.

DESIGN

Acute experimental trial.

SETTING

Operating room for animal experimental studies at a university hospital.

SUBJECTS

Five pigs (41.3 +/- 4.1 kg, mean body weight +/- SD).

INTERVENTIONS

The animals were anaesthetised and mechanically ventilated. Sixteen electrodes were attached on the thoracic circumference and used for electrical current injection and surface voltage measurement. Oleic acid was applied sequentially (total dose 0.05 ml/kg body weight) into the left pulmonary artery to produce selective unilateral lung injury.

MEASUREMENTS AND RESULTS

The presence of lung injury was documented by significant changes of PaCO2 (40.1 mmHg vs control 37.1 mmHg), PaO2 (112.3 mmHg vs 187.5 mmHg), pH (7.35 vs 7.42), mean pulmonary arterial pressure (29.2 mmHg vs 20.8 mmHg) and chest radiography. EIT detected 1) a regional decrease in mean impedance variation over the affected left lung (-41.4% vs control) and an increase over the intact right lung (+ 20.4% vs control) indicating reduced ventilation of the affected, and a compensatory augmented ventilation of the unaffected lung and 2) a pronounced fall in local baseline electrical impedance over the injured lung (-20.6% vs control) with a moderate fall over the intact lung (-10.0% vs control) indicating the development of lung oedema in the injured lung with a probable atelectasis formation in the contralateral one.

CONCLUSION

The development of the local impairment of pulmonary ventilation and the formation of lung oedema could be followed by EIT in an experimental model of lung injury. This technique may become a useful tool for monitoring local pulmonary ventilation in intensive care patients suffering from pulmonary disorders associated with regionally reduced ventilation, fluid accumulation and/or cell membrane changes.

Complications of intra-aortic balloon counterpulsation. The role of catheter size and duration of support in a multivariate analysis of risk

AIMS

The aim of this study was to assess the risk of intra-aortic balloon counterpulsation and to identify clinical and procedural variables that would predict complications.

METHODS AND RESULTS

We analysed 381 consecutive patients who were treated between 1977 and 1995 at our catheterization laboratory and/or medical intensive care unit. The complications considered relevant were limb ischaemia requiring catheter removal, vascular injury, bleeding requiring transfusion, embolic events, and infection. In eight patients the balloon could not be inserted. The rate of complications for the remaining 373 patients was 12.9%. Between 1977 and 1980, surgical insertion was performed using a 12 French catheter with a complication rate of 30.4% (seven of 23 patients). Percutaneous implantation, performed after 1981, had an overall complication rate of 11.7% (41 of 350 patients). Using thinner catheters for percutaneous placement was associated with a reduction in the rate of complications, from 20.7% (17 of 82 patients) for 12 French catheters to 9.9% (10 of 101 patients) for 10.5 French catheters (P = 0.04), and 8.4% (14 of 167 patients) for 9.5 French catheters (P = 0.006). Multivariate logistic regression analysis identified duration of counterpulsation > 48 h (odds ratio 3.6), catheter size (odds ratio 3.4 for 12 French catheters), peripheral vascular disease (odds ratio 2.7), and shock (odds ratio 2.0) as independent risk factors for counterpulsation-associated complications. When considering 9.5 French catheters only (167 patients, all after 1992), the sole remaining independent risk factor was duration of counterpulsation > 48 h (odds ratio 3.8). Those patients with 9.5 French catheters in whom counterpulsation did not exceed 48 h had a low complication rate of 3.9%.

CONCLUSION

The rate of percutaneous intra-aortic balloon counterpulsation complications was thus significantly reduced by employing thinner catheters. It was at an acceptable level for 9.5 French catheters, where a long duration of counterpulsation emerged as the most significant factor associated with complications. Whether using even thinner catheters in combination with a sheathless implantation technique further minimizes the risk of counterpulsation remains to be seen.

Serum phospholipase A2, amylase, lipase, and urinary amylase activities in relation to the severity of acute pancreatitis

OBJECTIVE

To compare serum phospholipase A2 activity with measurements of conventional enzymes as an indicator of the severity of acute pancreatitis.

DESIGN

Prospective study.

SETTING

University hospital, Finland.

SUBJECTS

80 Consecutive patients with acute pancreatitis.

INTERVENTIONS

Serum and urine samples were taken daily for a week after admission.

MAIN OUTCOME MEASURES

Serum phospholipase A2, amylase, lipase, and urinary amylase activities.

RESULTS

On admission, the serum amylase and lipase activities increased in parallel in all patients. However, the mean serum phospholipase A2 activity was three times higher in the patients with acute fulminant pancreatitis than in those with milder disease. The phospholipase A2 activity remained high during the course of the severe disease, whereas the other enzyme activities decreased appreciably during the first week. In contrast to the other enzyme activities that of serum phospholipase A2 correlated well with the severity of the acute pancreatitis. Heating at 60 degrees C for 45 minutes to inactivate the non-pancreatic thermolabile phospholipase A2 reduced the total serum phospholipase A2 activity more than the enzyme activity in the homogenates of pancreatic tissue, which suggests that extrapancreatic phospholipase A2 is present in serum. The receiver operating characteristic (ROC) curves confirmed the high sensitivity and specificity of serum phospholipase A2 activity with a mean (SEM) area under the curve up to 0.870 (0.062) compared with the other enzyme activities of which the highest area under the curve was 0.52 (0.089).

CONCLUSIONS

In contrast to amylase and lipase activities, measurement of serum phospholipase A2 activity is important in the assessment of the severity of acute pancreatitis so that optimal treatment may be given.

[LOGNORMAL-NLSQ-technique. Evaluation of a new mathematical method for determining blood volume]

This paper describes the investigation of a new mathematical method of calculating blood volume. The new method determines the blood volume by calculating the product of the mean circulation transit time. The mean transit time is calculated from the body transport function. To examine the accuracy of the LOGNORMAL-NLSQ technique, 45 concentration time curves were measured in an in vitro recirculation model with variable clearance. The calculated volume was 4% smaller than the actual volume. This may be attributed to the functional dead space within the model, and is tolerable for clinical situations. The LOGNORMAL-NLSQ technique might acquire considerable importance in future, especially since it provides accurate results very quickly.

Inhibition of serum phospholipase-A2 in acute pancreatitis by pharmacological agents in vitro

Phospholipase-A2 has been suggested as having a role in the pathophysiology of acute pancreatitis. The inhibition of phospholipase-A2 was studied in vitro using 17 pharmacological agents in the search for a specific therapy for acute pancreatitis. The inhibitory effect was tested using an isotopic assay system with 2-palmitoyl-(1-14C)-labelled dipalmitoyl phosphatidylcholine as a substrate and 10 microliters of serum from patients with acute necrotizing pancreatitis as an enzyme source. Among all agents tested, anti-inflammatory drugs inhibited enzyme activity most significantly: indomethacin (9.0 x 10(-3) mol l-1) decreased the phospholipase-A2 activity to one- tenth. The weak inhibitory effect could also be demonstrated using a lower concentration of 2 x 10(-5) mol l-1, which can be achieved after intravenous administration of 50 mg of this drug. The other drugs inhibited the enzyme activity at concentrations higher than those achieved after intravenous injections in clinical use. Diclofenac (3.1 x 10(-2) mol l-1) reduced the phospholipase-A2 activity by 93%, ketoprofen (2.0 x 10(-2) mol l-1) or chlorpromazine (1.4 x 10(-2) mol l-1) by 90%, tobramycin (1.7 x 10(-2) mol l-1) by 84%, doxycycline (9.0 x 10(-3) mol l-1) by 61%, dexamethasone (1.7 x 10(-3) mol l-1) by 62%, methylprednisolone (3.8 x 10(-2) mol l-1) by 50%, and pindolol (1.0 x 10(-4) mol l-1) by 59%. A weak inhibition of phospholipase-A2 activity was demonstrated by betamethasone, bupivacaine, digoxin, hydrocortisone, lidocaine, metoprolol, propranolol, and vancomycin. Indomethacin proved the most potent of the tested agents in inhibiting phospholipase-A2 activity in serum from patients with acute pancreatitis and should be further studied in vivo.

Risk factors, complications, and outcome in surgery: a multivariate analysis

OBJECTIVE

To correlate variables recorded perioperatively with morbidity and mortality in an attempt to assess the predictive value of these variables for the outcome of individual patients.

DESIGN

Prospective study.

SETTING

Teaching hospital, Germany.

SUBJECTS

6304 consecutive patients admitted for operation.

INTERVENTIONS

Recording of American Society of Anesthesiologists (ASA) class, age, sex, operation class (Hoehn), anaemia, hypertension, bronchopulmonary disease, diabetes mellitus, renal failure, major gastrointestinal disease, type of anaesthesia, operation (and whether emergency or elective), and duration of operation. All these factors were subjected to logistic regression analysis.

MAIN OUTCOME MEASURES

Odds ratio (OR), sensitivity, specifity, and positive and negative predictive values.

RESULTS

We studied 6304 patients of whom 140 died postoperatively and 1432 developed complications from which they survived. The variable that had most influence on the risk of postoperative complications was the ASA class (ASA class 4, OR 4.2, and ASA class 3, OR 2.2) followed by the severity of the operation (OR 1.86). An uncomplicated course was correctly predicted in 96%, but complications were correctly predicted in only 16%. The positive predictive value was 57%, and negative predictive value 80%.

CONCLUSIONS

Despite the fact that we considered a large number of variables we were unable to predict the risk of complications for individual patients with any accuracy.

Modelling of non-linear pharmacokinetics in sheep after short-term infusion of cardiotoxic doses of imipramine

Imipramine was administered to sheep (n = 10) by intravenous infusion in high doses (450 mg-900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration-time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n = 5) and without (n = 5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration-dependent clearance resulting in non-linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.

[Asymptotic behavior of calculated concentration time curves]

The measured concentration time curve of an injected substance is often used as a basis for calculating the distribution volume. For the first time, the present paper describes a generally applicable formula for calculating the asymptote of a concentration time curve in medical applications. With a knowledge of this formula, previously unexplained phenomena (varying results obtained from two different methods of calculating the distribution volume) can now be understood. At the same time, errors of methodology (choice of injection and measuring sites) can be avoided.

Serum complex of trypsin 2 and alpha 1 antitrypsin as diagnostic and prognostic marker of acute pancreatitis: clinical study in consecutive patients

OBJECTIVE

To estimate the usefulness of serum concentrations of the complex of trypsin 2 and alpha 1 antitrypsin in diagnosing and assessing the severity of acute pancreatitis in comparison with serum C reactive protein, amylase, and trypsinogen 2 concentrations (reference markers).

DESIGN

Markers were measured in consecutive patients admitted with acute abdominal pain that was either due to pancreatitis or to other disease unrelated to the pancreas (controls).

SETTING

Department of surgery of a teaching hospital in Helsinki.

SUBJECTS

110 patients with acute pancreatitis and 66 with acute abdominal diseases of extrapancreatic origin. On the basis of the clinical course, acute pancreatitis was classified as mild (82 patients) or severe (28 patients).

MAIN OUTCOME MEASURES

Clinical diagnosis of acute pancreatitis and severity of the disease.

RESULTS

At admission all patients with acute pancreatitis had clearly raised concentrations of trypsin 2-alpha 1 antitrypsin complex (32 micrograms/l), whereas only three of the controls had such values. Of the markers studied, trypsin 2-alpha 1 antitrypsin complex had the largest area under the receiver operating curve, both in differentiating acute pancreatitis from extrapancreatic disease and in differentiating mild from severe disease.

CONCLUSIONS

Of the markers studied, trypsin 2-alpha 1 antitrypsin complex was the most accurate in differentiating between acute pancreatitis and extrapancreatic disease and in predicting a severe course for acute pancreatitis.

ASA classification and perioperative variables as predictors of postoperative outcome

In a prospective study of 6301 surgical patients in a university hospital, we examined the strength of association between ASA physical status classification and perioperative risk factors, and postoperative outcome, using both univariate analysis and calculation of the odds ratio of the risk of developing a postoperative complication by means of a logistic regression model. Univariate analysis showed a significant correlation (P < 0.05) between ASA class and perioperative variables (intraoperative blood loss, duration of postoperative ventilation and duration of intensive care stay), postoperative complications and mortality rate. Univariate analysis of individual preoperative risk factors demonstrated their importance in the development of postoperative complications in the related organ systems. Estimating the increased risk odds ratio for single variables, we found that the risk of complication was influenced mainly by ASA class IV (risk odds ratio = 4.2) and ASA class III (risk odds ratio = 2.2). We conclude that ASA physical status classification was a predictor of postoperative outcome.

Myocardial extraction of bupivacaine in anaesthetized sheep and by hearts of sheep and rats in vitro

We observed the in vivo kinetics of bupivacaine in the cardiopulmonary system, particularly in the pulmonary artery, the upper part of the descending aorta and the coronary sinus of anaesthetized sheep, each of which received a high dose infusion into the central vein. In some experiments dilution curves were monitored for the non-extracted dye, indocyanine green. Concentrations of bupivacaine were approximately 20% lower in the aorta than in the pulmonary artery. This gradient of bupivacaine was present across the lung for 5-10 min. Concentrations of bupivacaine in the coronary venous plasma were also markedly lower than at the arterial site. Initially more than 50% of the amount of bupivacaine at the arterial site was removed by the heart. Later, the myocardial extraction ratio decreased and plateaued at a value of 0.30-0.40. At this time, concentrations of bupivacaine in the pulmonary artery were approximately 12 micrograms ml-1. Therefore, approximately 0.3-0.6 mg of bupivacaine were extracted per minute by the sheep heart in vivo. On the other hand, isolated perfused rat hearts did not substantially remove bupivacaine (2 micrograms ml-1) from the medium. Approximately one-third of 14C-bupivacaine was retained in slices of rat and sheep myocardial tissue. However, there was no evidence that metabolism played a substantial role in the cardiac kinetics of bupivacaine.

Serum trypsinogen-2 in the prediction of outcome in acute necrotizing pancreatitis

BACKGROUND

The accuracy of serum trypsinogen-2 in predicting the severity of acute necrotizing pancreatitis (ANP) was prospectively evaluated in 52 consecutive patients.

METHODS

A new sensitive immunofluorometric assay was used for serum trypsinogen-2,

RESULTS

Mean values during the first 24 h were 42.1 micrograms/l in control patients, 1435 micrograms/l in uncomplicated cases, and 4090 micrograms/l in complicated or fatal cases. There was a significant difference in serum trypsinogen-2 values between patients with uncomplicated and complicated disease (p = 0.002) already on admission. When a cutoff level of 1000 micrograms/l was used, patients with uncomplicated ANP were differentiated from patients with complicated ANP with a sensitivity of 91% and with a specificity of 71%.

CONCLUSIONS

The immunofluorometric assay of serum trypsinogen-2 is a sensitive and specific method for prediction of the severity of the disease in necrotizing pancreatitis.

Serum samples from pancreatectomized patients contain trypsinogen immunoreactivity

The concentrations of trypsinogen-1 and -2 in serum samples from patients who have undergone pancreatectomy were measured by highly sensitive and specific time-resolved immunofluorometric assays. The isoenzyme pattern was determined by ion-exchange chromatography and determination of immunoreactivity in the fractions. All samples contained trypsinogen-2, the mean level being one fifth of that in healthy controls. Trypsinogen-1 was detected in one of nine samples. In addition to the main trypsinogen isoenzymes, we observed in normal serum two trypsinogen isoenzymes previously found in mucinous ovarian cyst fluid. Our results suggest that trypsinogen is not exclusively expressed by the pancreas and certain tumors but that it also may be produced by normal extrapancreatic tissues. This should be considered when an assay of trypsinogen in serum is used for clinical purposes.

Sensitivity to Nd:YAG induced laserthermia is a cell-type-specific feature not directly related to tumorigenic potential or proliferation rate

BACKGROUND AND OBJECTIVE

Laser-induced hyperthermia, laserthermia, is a promising new method for treating neoplasms. The response of different cell types to conventional hyperthermia varies [Bhuyan, Cancer Res 1979; 39:2277-2284; Raaphorst et al., Cancer Res 1979; 39:396-401]. We investigated the possible relationship between sensitivity to laser treatment and tumorigenic potential of three closely related cell types. Non-tumorigenic cells PYS-2 and differentiated F9S1 were compared to tumorigenic cells F9S1.

STUDY DESIGN/MATERIALS AND METHODS

The contact Nd:YAG laser was used in a continuous-wave mode with a power setting of 6W, exposure times were 2 and 4 min [Castrén-Persons et al., Lasers Surg Med 1991; 11:595-600; Castrén-Persons, unpublished data]. The frosted-end probe was placed in the middle of the well and a thermocouple was attached 5 mm from the tip of the probe. The total amount of energy was measured for each well. A 4 min, 44 degrees C water bath treatment was used as comparison. Untreated wells served as controls. May-Grünwald-Giemsa staining and 3H-thymidine labeling were used for the analysis.

RESULTS

Laserthermia killed all three cell types significantly more effectively than the water bath. PYS-2 cells were the most sensitive to the laser treatment. At the same temperature, PYS-2 cells were only slightly affected by water bath induced heating; the differentiated F9 cells were the most sensitive to this treatment. During the laser treatments, the energy required for holding the temperature seemed to depend not only on the cell type but also on the amount of cells treated: the more cells in the well, the more energy was needed.

CONCLUSION

Our results suggest that laser sensitivity is a cell-type specific feature which is not directly related to the proliferation rate or benign or malignant behavior of the cells.

Computation of the initial distribution of a drug by repetitive convolution with a circulatory transport function

Hereby we present a widely applicable computational method for the description of recirculation and distribution phenomena occurring immediately after intravenous injection of a substance. The intravascular concentration-time course, r, is described as r = c0 + g * r, where the asterisk denotes the convolution operation, c0 is the concentration-time course during the first passage of the substance at an arterial measuring site and g is the transport function of the body. If the body transport function is known, then the arterial concentration-time course of a substance can be predicted for different amounts, injection times and elimination rates. The site of interest can be chosen arbitrarily, i.e. the concentration-time course in the arterial circulation supplying any organ can be described. This might be of special interest for the optimal design of intravenous injections of contrast media, where initial concentrations at the region of interest determine the success of the diagnostic procedure.

Characterisation of a fungus reference material, and a guide for use

A reference material consisting of an edible fungus, Cantharellus tubaeformis, with certified levels of Pb, Cd, Zn, Cu, Mn, Cr, Ni, Co and Fe was produced, primarily for use in a project concerning metal determination in common edible fungi. The C. tubaeformis was dried, homogenised and sieved using non-contaminating equipment. It was then mixed thoroughly before bottling in polythene containers. Homogeneity was checked by multiple analysis of a number of containers, and was found to be satisfactory. Each metal was determined by at least two different methods of analysis. A total of ten laboratories participated in the certification process. All the metals analysed in this certified reference material showed good agreement with the levels found in fresh C. tubaeformis, when the difference in water content was accounted for. This indicates that no contamination of the fungus reference material occurred during the production. It is concluded that the 95% confidence interval for the true mean, as defined for the different metals, is of limited value from the user's point of view. Therefore, a more user-oriented way of presenting the results, based on the within- and between-laboratory standard deviations of the certification process, is suggested. These are 95/95% tolerance intervals within which the user's results should fall. Different intervals are given, one of which indicates the largest acceptable difference between duplicates and another for the acceptable range of future means.

Early antibiotic treatment in acute necrotising pancreatitis

Despite improvements in surgical treatment and intensive care, mortality from severe acute pancreatitis remains high. We have carried out a randomised study of 60 consecutive patients with alcohol-induced necrotising pancreatitis to find out whether early antibiotic treatment can improve outcome. 30 patients were assigned cefuroxime (4.5 g/day intravenously) from admission. In the second group, no antibiotic treatment was given until clinical or microbiologically verified infection or after a secondary rise in C-reactive protein. The inclusion criteria were C-reactive protein concentration above 120 mg/L within 48 h of admission and low enhancement (< 30 Hounsfield units) on contrast-enhanced computed tomography. There were more infectious complications in the non-antibiotic than in the antibiotic group (mean per patient 1.8 vs 1.0, p = 0.01). The most common cause of sepsis was Staphylococcus epidermidis; positive cultures were obtained from pancreatic necrosis or the central venous line in 14 of 18 patients with suspected but blood-culture-negative sepsis. Mortality was higher in the non-antibiotic group (seven vs one in the antibiotic group; p = 0.03). Four of the eight patients who died had cultures from pancreatic necrosis positive for Staph epidermidis. We conclude that cefuroxime given early in necrotising pancreatitis is beneficial and may reduce mortality, probably by decreasing the frequency of sepsis.

[Anesthesia with propanidid in a liposomal preparation. An experimental study in swine]

BACKGROUND

Propanidid was widely used as a short-acting i.v. anaesthetic until it was withdrawn due to severe haemodynamic side effects. It was presumed that anaphylactoid reactions with massive histamine release were caused by the solvent cremophor rather than by propanidid itself. A new liposomal preparation of propanidid was examined in this animal study and compared with propanidid in cremophor solution and with propofol.

METHODS

Eighteen pigs were randomly assigned to one of the following groups: Group 1 (n = 6): Propanidid in liposomal preparation (PropaLip; Braun Melsungen, Germany). Anaesthesia was induced with 60 mg/kg, followed by continuous infusion of 400 mg/kg.h. Group 2 (n = 6): Propanidid in cremophor solution (PropaCrem; Sombrevin, Gedeon Richter, Budapest) 15 mg/kg, 100 mg/kg.h. Group 3 (n = 6): Propofol (Disoprivan, Zeneca, Plankstadt, Germany) 5 mg/kg, 20 mg/kg.h. After induction and tracheal intubation, the animals were ventilated with 50% oxygen in air. Basic monitoring included noninvasive blood pressure measurements, electrocardiographic monitoring, and capnography. In a short surgical procedure, arterial and pulmonary artery catheters were placed via the right carotid artery and right internal jugular vein, respectively. As soon as the animals responded to a pain stimulus a second anaesthetic induction was performed, followed by a 60-min continuous infusion of the agent studied with invasive haemodynamic monitoring including arterial and pulmonary arterial pressures and cardiac output. Blood samples were taken for the measurement of serum levels of adrenaline, noradrenaline, cortisol, aldosterone, adrenocorticotropic hormone, and histamine.

RESULTS

Intubation conditions and quality of anaesthesia were best in propofol animals, followed by PropaCrem animals. In spite of the large dose of 410 mg/kg.h, resulting in a volume load of as much as 16.4 ml/kg.h, the PropaLip animals showed evidence of poor anaesthetic quality. In group 1 we recorded the highest increases in heart rate (91 vs. 115/min), cardiac output (5.4 vs. 7.7 l/min), plasma catecholamine levels, and histamine concentrations (124-268 ng/ml).

CONCLUSIONS

In our animal study, propanidid in liposomal preparation failed to show promise as a new anaesthetic agent. Our results are discussed in view of a drug targeting the cells of the reticuloendothelial system, especially the liver, where liposomes are eliminated from the blood. This may result in the transport of propanidid to one of its major places of inactivation.

Pulmonary and left ventricular decompression by artificial pulmonary valve incompetence during percutaneous cardiopulmonary bypass support in cardiac arrest

BACKGROUND

In cardiac arrest, use of percutaneous cardiopulmonary bypass support (PCPS) may lead to left ventricular loading, with deleterious effects on the myocardium, and is often accompanied by an increase in pulmonary artery pressure. The present study was designed to assess the potential of artificially induced pulmonary valve incompetency to retrogradely decompress the left ventricle during PCPS in ventricular fibrillation.

METHODS AND RESULTS

Studies were performed using a standardized experimental animal model in sheep (n = 12; body weight, 77 to 112 kg). When PCPS was used during fibrillation, an increase in left ventricular pressure (from 21.4 +/- 5.0 mm Hg after 1 minute to 28.4 +/- 9.5 mm Hg after 10 minutes of fibrillation) was observed in all animals, with a simultaneous increase in pulmonary artery pressure in 6 animals, from 15.5 +/- 3.8 to 24.3 +/- 5.4 mm Hg (group A). In these animals, artificial pulmonary valve incompetency, which was induced by a special "pulmonary valve spreading catheter," led to effective decompression of both the pulmonary circulation (decrease in pulmonary artery pressure from 24.3 to 11.3 mm Hg) and the left ventricle (decrease in left ventricular pressure from 30.5 to 17.7 mm Hg). We simultaneously measured a decrease in the myocardial release of lactate (increase in arterial coronaryvenous difference in lactate content from -0.01 to 0.14 mmol/L), demonstrating the myocardial protective effect of the procedure. In contrast, in 6 animals without an increase in pulmonary artery pressure during PCPS (group B), artificial pulmonary valve incompetency did not reduce left ventricular loading, which was probably because of competent mitral valves in these animals.

CONCLUSIONS

In case of increasing pulmonary artery pressure during PCPS in cardiac arrest, artificial pulmonary valve incompetency might be a useful tool for effective pulmonary and retrograde left ventricular decompression.

[Concomitant hemodynamic effects of intracoronary injections of a new transpulmonary contrast medium]

AIM

A new transpulmonary echo contrast agent (SH U 508) was injected intracoronally to six anaesthetised sheep to examine its possible direct cardiac effects.

METHOD

SH U 508 was injected in randomised order in three different volumes (2, 4 and 8 ml; n = 12, 10, 9) with the same drug concentration of 200 mg/ml.

RESULTS

The 2 ml and 4 ml injections had no relevant effect on the arterial, pulmonary-arterial and ventricular pressures, on the left ventricular contraction velocity and on the myocardial blood flow (less than +/- 10% of the control value). The left ventricular relaxation velocity decreased by 20%. The disturbance of the left ventricular relaxation at a volume of 8 ml was pronounced (about 40% decrease). Slight left ventricular dysfunction further manifested itself in a decreased systolic pressure (-15%) and increased left ventricular enddiastolic pressure (20%).

CONCLUSION

In summary the overall effect of the intracoronary injections of SH U 508 exhibited only minor cardiac side effects. If the current results are extrapolated to peripheral-venous application, the clinically required central-venous 8 ml injection of a 400 mg/ml suspension is not expected to produce any coronary haemodynamic side effects, due to drug dilution in the pulmonary circulation and resulting low intra-coronary concentrations.

Peripheral and cardiac effects of a new phosphodiesterase inhibitor in comparison with enoximone

The effect of the new phosphodiesterse inhibitor R80122 (E)-N-cyclohexyl-N-methyl-2-[[[phenyl(1,2,3,5-tetrahydro-2-oxoimidazo [2,1-b]-quinazolin-7-yl)methylene] amino]oxy]acetamide, (CAS 133718-29-3) on haemodynamic parameters and myocardial oxygen consumption were intraindividually compared with those of enoximone, a clinically established phosphodiesterase inhibitor. In 12 anaesthetised sheep the drugs were given in randomized order as i. v. infusions for 6 min at each setting (10, 20 and 30 micrograms.kg-1.min-1 (R80122) and 32, 64 and 96 micrograms.kg-1.min-1 (enoximone)). R 80122 as well as enoximone caused a significant increase in cardiac inotropism with a simultaneous increase of myocardial oxygen consumption. The peripheral resistance was significantly decreased by both drugs. The haemodynamic effects elicited by the application of equieffective doses of R80122 and enoximone did not show any differences.