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J Meyer

Publications and source records attributed to J Meyer.

At least 559 records · Page 31Linked to original sources
PubMed1993

Transthoracic and transesophageal echocardiography to diagnose ventricular septal rupture: importance of right heart infarction.

BACKGROUND: Rapid and accurate diagnosis of ventricular septal rupture (VSR) remains difficult, and the monitoring of hemodynamic deterioration is a prerequisite for the institution of adequate therapy. The timing of surgical repair is a matter of controversy. METHODS: Transthoracic, transesophageal, color Doppler, and contrast echocardiography were evaluated in 17 patients with VSR in whom the diagnosis was confirmed by catheterization, surgery, or necropsy. RESULTS: Routine transthoracic echocardiography visualized VSR in four out of 17 patients and, with additional views, in 12 out of 17 patients. Color Doppler echocardiography identified the rupture in 15 out of 16, and contrast echocardiography in 11 out of 11 patients. VSR was identified using transesophageal echocardiography in six out of nine patients, and using color Doppler and contrast echocardiography in all patients. Eight out of 10 patients who developed right heart myocardial infarction (RMI) died, whereas all patients without RMI survived (P = 0.0070). Similarly, eight out of 10 patients with shock died, whereas all patients without survived (P = 0.0070). Shock occurred more often in patients with RMI (eight out of 10) than in patients without (two out of six). All patients with both RMI and shock died, whereas those without both conditions survived (P = 0.0002). CONCLUSION: Modern echocardiography is the method of choice in the diagnosis of VSR. Right ventricular function should be evaluated in patients with VSR because patients with RMI are at high risk of hemodynamic deterioration, with poor outcome. RMI, visible as abnormal wall motion, was identified better with transesophageal than with transthoracic echocardiography.

Aged↗
PubMed1993

Coronary artery remodeling in atherosclerotic disease: an intravascular ultrasonic study in vivo.

BACKGROUND: Pathologic studies have revealed that coronary arteries undergo compensatory enlargement in the presence of atherosclerosis. METHODS: In order to assess coronary artery remodeling in vivo, we used intravascular ultrasound to examine 46 patients (36 men and 10 women; aged 58.2 +/- 6.8 years) with non-calcified plaques. The vessel, lumen, and plaque areas of the atherosclerotic and of normal proximal and distal segments were determined. RESULTS: A total of 92 atherosclerotic segments were analyzed. The degree of stenosis ranged from 9.2 to 92.8% (mean 34.1 +/- 16.9%) and the plaque area from 2 to 19.6 mm2 (mean 6.3 +/- 3.6 mm2). The vessel area of the atherosclerotic segment (mean 20.4 +/- 7.3 mm2) was larger than that of the proximal segment (mean 18.7 +/- 7.3 mm2, P = 0.018). The vessel area increased in proportion to plaque area. This relationship can be described using the equation y = 23.5(1-e-0.35x). The difference between the vessel area in the atherosclerotic segment and that in the proximal normal segment correlated with the percentage of stenosis (r = 0.53, P < 0.005) until the degree of stenosis exceeded 45%. CONCLUSION: This study indicates that coronary artery remodeling, previously observed in pathologic studies, can be evaluated using intravascular ultrasound in vivo. As a result of the compensatory enlargement of the vessel, coronary angiography cannot be used to detect or exclude the early signs of coronary atherosclerosis.

Adult↗
PubMed1993

Absorption of the stable prostacyclin analogue iloprost through the ulcer base in chronic venous insufficiency.

Iloprost, a stable prostacyclin analogue, is known to have beneficial effects on the disturbed microcirculation. To develop a topical application for venous leg ulcers it is necessary to know the extent to which iloprost might be absorbed through the ulcer base. The aim of this study was to measure the absorption kinetics of iloprost solutions in increasing concentrations and doses (0.004% [15 micrograms]-0.006% [30 micrograms]) in 23 patients. There was considerable variation amongst the patients in the amount of iloprost absorbed. In 40% of patients no iloprost could be detected in the plasma, whereas in others up to 82% of the iloprost applied was absorbed through the ulcer base. High iloprost plasma levels provoked flushing in two patients. The highest plasma levels were always reached during the first hour after application. There was no direct relation between the ulcer size and the amount of iloprost absorbed. Iloprost concentrations up to the highest concentration applied (0.006%) were well tolerated locally.

Administration, Cutaneous↗
PubMed1993

Ventilation and heart rate response during exercise in normals: relevance for rate variable pacing.

The observation of a close relationship of heart rate to oxygen uptake (HR-VO2) and heart rate to minute ventilation (HR-VE) has been shown to be of particular value in rate variable pacing. However, the impact of anaerobic threshold (AT) for the HR-VO2 and HR-VE slope has been studied less. Twenty-three male and 16 female subjects, mean age 52 +/- 7 years, were selected in whom complete heart catherization and extensive noninvasive studies excluded major cardiopulmonary disease. Semisupine bicycle exercise testing with analysis of respiratory gas exchange was performed using a ramping work rate protocol with work increments of 20 watts/min. At the respiratory AT, determined by the V slope method, oxygen uptake (VO2-AT) was 15.2 +/- 3.0 mL/kg in males versus 13.8 +/- 2.3 mL/kg in females and heart rate (HR-AT) was 109 +/- 18 beats/min versus 119 +/- 20 beats/min, respectively. Heart rate was highly correlated (r > or = 0.9) to VO2 and minute ventilation (VE). A linear regression for HR-VO2, however, was found only in 16/39 and for HR-VE in 11/39 subjects. Assuming the AT as the breakpoint of two linear curves, it could be demonstrated that compared to low exercise HR appeared to increase at maximal exercise more in relation to VO2 but less in relation to VE; in men the individual slopes for HR-VO2 were 2.6 +/- 0.7 below but 3.2 +/- 1.0 above AT (P < 0.05) and the slopes for HR-VE were 1.6 +/- 0.5 below but 1.0 +/- 0.4 above AT (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗
PubMed1993

Empiric red cell transfusion in asymptomatic preterm infants.

In a prospective randomized trial, asymptomatic very low-birth-weight infants in a neonatal intensive care unit were either electively transfused with red cells to maintain capillary haematocrit greater than 0.35 l/1 (group 1; n = 9), or were not transfused (group 2; n = 10). Individuals from both groups were excluded if they subsequently received non-elective transfusions, necessitated by their clinical condition. Electively transfused infants gained weight more rapidly than their non-transfused counterparts, but the duration of hospitalization was not shortened. Criteria of morbidity, such as patent ductus murmurs, apnoea and failure to thrive, were similar in both groups. We conclude that in the absence of clinical indications, transfusion to achieve a hematocrit greater than 0.35 l/1 as an empiric procedure, improves weight gain but the risks of transfusion are likely to outweigh the benefits.

Blood Component Transfusion↗
PubMed1993

High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions.

OBJECTIVE: To prove the safety and effectiveness of high frequency rotational ablation of coronary artery stenoses and occlusion in humans. SUBJECTS: 106 patients with symptoms (91 men, 15 women) who had 67 significant stenoses, mainly types B and C, and 46-chronic occlusions. MAIN OUTCOME MEASURES: Mean change in diameter stenosis after rotational angioplasty alone and in combination with percutaneous transluminal coronary angioplasty immediately after treatment and 24 hours and six months later; restenosis rates at six months; complication of treatment. RESULTS: Rotational ablation could not be used in five stenoses and 16 chronic occlusions because of inability to reach or cross the lesion with the Rotablator guide wire. In four cases rotational ablation failed. Initial angiographic and clinical success by rotational ablation was achieved in 40 of the 67 stenoses (60%) and in 18 of the 46 chronic occlusions (39%). Additional balloon angioplasty was performed in 45 patients, increasing the success rates to 79% and 54%, respectively. In the 62 stenoses treated by rotational ablation the angiographic diameter stenoses were reduced from 76% (SD 14%) to 32% (14%) after Rotablator treatment alone and from 75% (11%) to 33% (17%) with additional balloon angioplasty. In the 30 chronic occlusions treated by rotational ablation the angiographic diameter stenoses were reduced to 38% (18%). At six months angiographic restenosis was evident in nine of the 25 (36%) stenoses treated with rotational ablation alone, in seven of the 22 (32%) stenoses treated with rotational and balloon angioplasty, and in 14 of the 24 (58%) chronic occlusions. There were no procedural deaths and two patients (2%) underwent emergency coronary artery bypass grafting. Although no transmural infarction occurred, there were five (6%) non-Q wave infarctions (two embolic side branch occlusions, two subacute occlusions, and one acute occlusion). Clinically insignificant slight increases in creatine kinase activity were seen in five patients (6%). Severe coronary artery spasm unresponsive to medical treatment was provoked in seven cases (8%). CONCLUSIONS: High frequency rotational ablation is a safe and effective method for treating type B and C coronary artery lesions with results comparable to percutaneous transluminal coronary balloon angioplasty. The combined use of rotational ablation and balloon angioplasty is feasible and is necessary in about half of all procedures, in most cases because the lumen created by the biggest burr is too small.

Adult↗
PubMed1993

Effect of medical and surgical therapy on aortic dissection evaluated by transesophageal echocardiography. Implications for prognosis and therapy. The European Cooperative Study Group on Echocardiography.

BACKGROUND: Aortic dissection still has a poor prognosis despite progress in therapy. Therefore, this prospective follow-up study was designed to determine whether the degree of communication between true and false lumen in relation to the type of dissection, analyzed by transesophageal echocardiography, influences the risk after initiation of medical or surgical therapy. METHODS AND RESULTS: In eight centers, 168 patients (124 men and 44 women) of age range of 23-84 years with proven aortic dissection were examined by transesophageal echocardiography in the acute phase, after start of medical and/or surgical therapy, and during follow-up (0-65 months; mean, 10 months). Analyses were performed prospectively according to a detailed study protocol. Patients were subdivided by transesophageal echocardiography according to a modified DeBakey classification. Type I aortic dissection was found in 35%, type II aortic dissection in 17%, and type III aortic dissection in 48%. Preoperative mortality was 3%, 7%, and 2%, and survival rates were 52%, 69%, and 70%, respectively. Type III aortic dissection could be subdivided into those with communication and antegrade dissection (ca) (50%), with communication and retrograde dissection limited to the descending aorta (cr desc) (10%), with dissection extended to the aortic arch and ascending aorta (cr asc) (27%), and with noncommunicating (nc) aortic dissection (13%). An open false lumen with no thrombus formation was present in types I, II, III ca and III cr asc aortic dissection in 17%, 21%, 39%, and 27% respectively, although it was most pronounced in types III nc and III cr desc (75% and 78%). During follow-up in patients who survived, thrombus was demonstrated in the false lumen in 80% of type I aortic dissection and 81% of types III ca and III cr asc. Open false lumen was seen in type II aortic dissection in 18%. Spontaneous healing was found in 4% with type II and 4% with type III aortic dissection (mainly in patients with type III nc aortic dissection). Patients with fluid extravasation, pleural effusion, pericardial tamponade, and periaortic effusion as well as mediastinal hematoma had a mortality of 52%. Reoperations were necessary in 12-29%, with the highest rate in patients with type III ca aortic dissection. Survival for patients with types III nc and III cr desc aortic dissection was higher than those with types I, II, III ca, and III cr asc. CONCLUSIONS: Preoperative mortality appears to be reduced by transesophageal echocardiography, allowing rapid initiation of treatment. Intraoperative and postoperative mortality in aortic dissection remains high. Risk factors are fluid extravasation and an open false lumen with high communication. Thrombus formation in the false lumen can be regarded as a good prognostic sign. Surgery appears to be only a first step in the treatment of aortic dissection. Second surgery or closure of entry sites based on intraoperative echocardiography may be considered to induce thrombus formation and reduce aortic wall stress.

Adult↗
PubMed1993

Effects of halothane anesthesia on vasoconstrictor response to NG-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis, in sheep.

This study tests the hypothesis that halothane-induced inhibition of the endothelium-derived relaxing factor/nitric oxide (EDRF/NO) pathway significantly contributes to cardiovascular performance and thus reduces the vasoconstrictor response to NO synthesis inhibitors in vivo. We determined the effects of the administration of the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in chronically instrumented, halothane-anesthetized sheep and in awake control animals. Six sheep underwent halothane anesthesia (1.5 vol%) with mechanical ventilation. Five sheep were studied in the awake state with spontaneous breathing. Both groups received a bolus of L-NAME (25 mg/kg), followed 4 h later by L-arginine (300 mg/kg) to reverse the effects of L-NAME. L-NAME administration caused a significant increase in pulmonary and systemic vascular resistance (P < 0.05) in both groups. However, L-NAME produced a sharp increase in mean arterial and pulmonary artery pressures only in the control group, whereas the pressor response in the halothane group was attenuated. Cardiac output, which was significantly lower after L-NAME administration in both groups, increased after L-arginine. The results suggest that halothane does not significantly alter the EDRF/NO-mediated effects on the vasculature but potentiates the cardiac depressant effect of L-NAME.

Anesthesia, Inhalation↗
PubMed1993

Clinical and functional results of abdominal rectopexy with absorbable mesh-graft for treatment of complete rectal prolapse.

OBJECTIVE: To report the long term results of abdominal rectopexy in patients with complete rectal prolapse. DESIGN: Ongoing prospective randomised study. SETTING: Department of Surgery, Westfälische Wilhelms-University, Münster. SUBJECTS: 47 patients with complete rectal prolapse operated on between 1982 and 1989. INTERVENTIONS: Abdominal rectopexy with absorbable mesh made of either polyglycolic acid (n = 17) or polyglactine 910 (n = 30). MAIN OUTCOME MEASURES: Postoperative complications and late results at a mean of 50.5 (range 2-102) months after operation. RESULTS: Thirteen patients (28%) developed postoperative complications, most of them minor; there was one enterocutaneous fistula. Thirty five patients (74%) were available for late follow up. There were no case of recurrent prolapse and 5 (14%) had developed mucosal prolapse. Of the 22 patients who had been incontinent before operation, 8 had become totally continent and 6 partially continent Overall continence improved in 18 (51%) of the 35 patients. Three patients who were continent before operation had become incontinent. CONCLUSION: Absorbable mesh is a suitable material for abdominal rectopexy.

Absorption↗
PubMed1993

[Diastolic flow analysis of the left ventricle after myocardial infarct].

The diastolic function of the left ventricle was investigated in 12 normal young volunteers, 10 older volunteers, 10 patients without evidence of coronary artery disease, 26 patients with inferior wall and 19 patients with anterior wall infarction at eight locations of the total circumference of the left ventricle using pulsed wave Doppler. The ratio of early diastolic inflow (Vmax E) to the maximal velocity of atrial contraction (Vmax A) was determined. Furthermore, the delay between the end of electrical diastole until the end of the A-wave of the pulsed Doppler was measured. The results were compared with a clinically used marker of myocardial ischemia, treadmill exercise testing. The E/A ratio was 2.03 +/- 0.51 in normal volunteers, 1.16 +/- 0.41 in older volunteers, 1.41 +/- 0.59 in patients without evidence for coronary artery disease, 1.28 +/- 1.13 in patients with inferior and 1.08 +/- 0.41 in patients with anterior wall infarction (p = 0.020 ANOVA). The diastolic delay at the apex was 47.3 +/- 8.9 ms in normal volunteers, 78.3 +/- 8.3 ms in older volunteers, 79.1 +/- 13.7 ms in patients without coronary artery disease, 109.1 +/- 12 ms in patients with inferior and 169.5 +/- 18.8 ms in patients with anterior wall infarction (p = 0.000 ANOVA). There was a correlation between the latter parameter of delay and the amount of pathological wall segments at wall motion analysis (r = 0.61, p = 0.007). In two patients with anterior myocardial infarction (11%) with significant diastolic delay intraventricular thrombi developed consecutively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Diagnostic value of transesophageal echocardiography in diseases of the heart valve system].

Due to high resolution transesophageal echocardiography has been proven to have additional diagnostic benefits in valvular heart disease. The quantification of aortic and mitral valve insufficiency is possible by the use of semiquantitative methods. In aortic valve insufficiency the relation of the regurgitant jet width to the left ventricular outflow tract and in mitral valve insufficiency the relation of the regurgitant jet area to the left atrium are the parameters with the most accurate sensitivity. The main advantage of the method in this point is the rapid detection of morphological pathology at the valves. The development of multiplane transducers enhanced the quantification of aortic valve stenosis which is performed by planimetry of the orifice area in an ideal cross-section of the valve reached at a mean angle of 46 degrees. The high resolution image of mitral valve anatomy leads to the intraoperative use of the method during valve repair identifying inadequate surgical correction, which can be revised instantly. Visualization of the valvular and subvalvular mitral apparatus enables a more reliable indication for valvuloplasty by detecting the presence or absence of atrial thrombi and assessing the severity of calcification, the guide catheter and the balloon placement. Transesophageal echocardiography is the method of choice in the detection and measurement of vegetations and abscesses in infective endocarditis. Imaging an increasing extent of a vegetation during follow-up investigations can lead to the necessity of surgical intervention for preventing embolic events. The transesophageal approach especially in combination with color-doppler flow imaging is superior to the transthoracic method in the detection of abscesses and secondary complications like communication to adjacent structures or implication of the mitral valve. In this point the use of multiplane probes permits a more accurate assessment of the extent and the spatial configuration of additional masses. Concerning valve prostheses the detection rate of vegetations, abscesses as well as degenerations of bioprostheses is higher using the transesophageal method than the transthoracic approach. Abscesses located near the right coronary sinus or in the ventricular septum are difficult to detect due to shadowing caused by prosthetic artefacts. The visualization of bioprostheses allows the measurement of the thickness of the leaflets which is necessary for the diagnosis of valve sclerosis or degeneration. In combination with color-doppler flow imaging the method allows the differentiation of transvalvular and perivalvular regurgitation. The movements of the occluder can be imaged leading to a more reliable diagnosis of obstruction in combination with the trans-thoracic use of doppler-methods.

Aortic Valve↗
PubMed1993

The processing of macronuclear DNA sequences during macronuclear development of the hypotrichous ciliate Stylonychia lemnae.

The organization of two macronuclear DNA sequences in the polytene chromosomes of the hypotrichous ciliate Stylonychia lemnae and their processing from the micronucleus via the polytene chromosome stage up to the macronucleus was analyzed. The overall organization of these sequences in the polytene chromosomes resembles that described for the micronucleus of other hypotrichous ciliates, i.e. they are interrupted by internal eliminated sequences and not associated with telomeric sequences. The spacer region between the genes is bordered by direct repeats and inverted repeats are found at the termini of macronuclear sequences and in the spacer region. The organization of these macronuclear DNA sequences in the micronucleus was analyzed by polymerase chain reactions. The results obtained show that in the sequences analyzed no DNA reorganization occurs during polytene chromosome formation.

Animals↗
PubMed1993

[Revascularization measures after acute myocardial infarct].

Thrombolytic therapy in acute myocardial infarction reduces mortality significantly. This acute effect seems to be counterbalanced by the increased mortality during follow-up whether or not the patient has been treated with thrombolytic therapy. Thrombolysis seems to be a first step in the treatment of acute myocardial infarction. Revascularization procedures are able to improve patient prognosis. Long-term follow-up demonstrated this fact whether or not PTCA was performed in the acute setting or on an elective basis. The 6-year survival was 80%. This survival rate was higher for patients who underwent PTCA than for those who were not undergoing PTCA and those who had no reperfusion of the coronary artery. The best prognosis was found for patients with coronary bypass surgery, indicating that revascularization should be the aim of treatment. The 6-year survival rate was found to be 92% and is thus in the range of patients with coronary artery disease. Acute infarct PTCA is limited to patients with cardiogenic shock and is particularly useful for patients with occlusion of the main stem of the left coronary artery. Acute infarct PTCA is also recommended in patients with contraindications for thrombolytic therapy, when interventions can be performed rapidly, when a large infarct size is present and infarct time is less than 4 hours. Whether or not RESCUE-PTCA should be recommended is under investigation. Patients with an open coronary artery have a better prognosis than patients with occluded coronary arteries, but during the acute stage, spontaneous recanalization is present in many patients. The RESCUE study will address this question. Elective PTCA is recommended as well as coronary bypass surgery, when successful reperfusion is achieved and one-or two-vessel disease is present or there is a two- or three-vessel disease or main stem involvement, respectively. In patients with coronary lesions less than 70% conservative treatment is useful. The guidelines of the American College of Cardiology and the American Heart Association are strongly recommended.

Angioplasty, Balloon, Coronary↗
PubMed1993

'Determination' of sugar alcohol and Polydextrose absorption in humans by the breath hydrogen (H2) technique: the stoichiometry of hydrogen production and the interaction between carbohydrates assessed in vivo and in vitro.

The production of hydrogen from substrates and substrate mixture of sugar alcohols and Polydextrose was determined, both in vivo using the breath hydrogen test, and in vitro, using human faecal microorganisms in anaerobic culture. One objective was to test a previous assumption that the stoichiometry of hydrogen production from different alternative carbohydrates is similar. Another objective was to discover whether hydrogen responses from mixtures of substrates were simply additive, or whether interactions occurred. The breath tests were performed in a 10 subject x 10 substrate factorial design with substrates and substrate mixtures (5-11 g) administered in 42 g chocolate confectionery. Incorporation of the alternative carbohydrates lactitol (L), Isomalt (I) and Polydextrose (P) into otherwise conventional confectionery increased breath hydrogen production by approximately 112, 73 and 11%/g respectively. There was no interaction between L and I or between P and I, but a combination of L and P approximately doubled the breath hydrogen anticipated from their individual contributions (P < 0.05). Anaerobic cultures showed a sixfold range in the efficiency of converting individual substrates and mixtures to hydrogen gas (0.003-0.018 kJ H2 per kJ carbohydrate). The positive interaction between L and P, and the lack of interaction between L and I, and between P and I, found in vivo were reproduced in vitro. The work showed that interpretation of the hydrogen breath test is confounded by differing stoichiometries for hydrogen production, by interaction between substrates and by an uncertain extent to which small intestinal hydrolysis yielding species with a fermentation stoichiometry that differs from the parent substrate.

Absorption↗
PubMed1993

[Multicenter results of coronary implantation of balloon expandable Palmaz-Schatz vascular stents].

Intracoronary stenting was designed to handle acute vessel closure after balloon angioplasty and to reduce the rate of restenosis. In three cardiology centers the implantation of 200 balloon-expandable Palmaz-Schatz stents was attempted in 179 patients. The implantation was successful in 170 patients (95%). During bail-out implantation for acute vessel closure or symptomatic dissections after balloon angioplasty, implantation succeeded in 60 (91%) of 66 attempted patients, who recovered immediately from ischemia. Three patients received emergency bypass surgery and three patients were kept on medical therapy. Restenosis after 4 to 6 months, defined as > 50% diameter reduction, was documented angiographically in 18 (15.3%) of 118 presently controlled patients. Patients with single stent implantation (n = 106) presented a late restenosis rate of 10.4% in contrast to patients with multiple stent implantation (n = 12), who presented a restenosis rate of 58.4%. Similar results on restenosis were found for patients with elective and bail-out stent implantation. Acute thrombotic stent occlusion occurred in three patients (1.8%) during the first 24 h after stenting. Three to 9 days after implantation subacute stent thrombosis occurred in 15 (8.8%) of 170 patients. Despite adequate therapy including thrombolysis, balloon angioplasty or emergency bypass surgery in 14 of 15 patients Q-wave myocardial infarction was documented in six patients and non Q-wave myocardial infarction in five patients. The following parameters were identified as risk factors for the development of subacute stent thrombosis: bail-out indication, unstable angina, type C lesion, stenosis length > 1.5 cm, plaque area > 3.5 mm2, symptomatic dissection after balloon angioplasty, incomplete wrapping of the dissection after stenting and residual distal vessel irregularities after stenting. Bleeding complications occurred in 12.4% of the patients and were related to the anticoagulation and antiaggregation therapy. In conclusion, the implantation of Palmaz-Schatz stents is an excellent bail-out device to treat acute vessel closure or symptomatic dissections after angioplasty. Elective and bail-out single stent implantation is associated with a reduced rate of restenosis when compared to conventional balloon angioplasty. At present, subacute stent thrombosis and bleeding complications are the major limitations with a combined rate of 15.9%.

Adult↗
PubMed1993

[Cardiopulmonary effects of CPPV (continuous positive pressure ventilation) and IRV (inverse ratio ventilation) in experimental myocardial ischemia].

Continuous positive pressure ventilation (CPPV) is an established therapy for treatment of acute respiratory failure (ARF). However, cardiac performance may be severely disturbed due to elevated intrathoracic pressure, inducing a decrease in cardiac output (CO) and oxygen delivery (DO2). Alternatively, mechanical ventilation with prolonged inspiratory to expiratory duration ratio (inversed ratio ventilation IRV) has been successfully used in ARF. No data are available about IRV in acute haemodynamic oedema. Thus, the cardiopulmonary effects of CPPV (positive end-expiratory pressure [PEEP] = 10 cm H2O) and IRV (inspiration to expiration duration ratio [I:E] = 3.0) were studied in nine dogs (body weight 29.9 +/- 4.3 kg) before and after induction of myocardial ischaemia. METHODS. Continuous intravenous anaesthesia and muscle paralysis were provided by 1.2 mg.kg-1 x h-1 piritramide and 0.08 mg.kg-1 x h-1 pancuronium, and the animals were ventilated with intermittent positive pressure ventilation (IPPV) as reference method. Cardiocirculatory performance was determined by means of heart rate (HR), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP) and left ventricular end-diastolic pressure (LVEDP). Cardiac output (CO) was determined by thermodilution method. Systemic vascular resistance (SVR) was calculated. Pulmonary function was assessed by arterial and mixed venous blood gas tension for oxygen (PaO2, PvO2) and carbon dioxide (PaCO2). Functional residual lung capacity (FRC) was measured by means of the foreign gas wash-in method using helium as inert gas, and determination of extravascular lung water (EVLW) using the thermal-dye indicator technique. CPPV and IRV were studied in random sequence in the control phase and 60 min after induction of acute left ventricular ischaemia, which was achieved by occlusion of the ramus interventricularis anterior. RESULTS. During the control phase CPPV induced an increase in MPAP (P < 0.05), CVP (P < 0.05) and PAOP (P < 0.05). HR and MAP remained unchanged, whereas CO decreased by 16% (P < 0.05). FRC was elevated by 25 ml.kg-1 (P < 0.01), but not EVLW (9.1 +/- 3.5 ml.kg-1). There was no improvement in oxygenation; instead, oxygen delivery (DO2) decreased (P < 0.05). During inversed ratio ventilation MPAP, CVP, PAOP increased, but less than during CPPV. FRC was elevated mu 7.0 ml.kg-1 (P < 0.05), which was significantly less than during CPPV (P < 0.05). EVLW revealed no differences. During IPPV in the ischaemia phase cardiopulmonary performance deteriorated significantly. CO decreased by 19% (P < 0.05), whereas HR, MPAP, CVP and PAOP increased (P < 0.05). PaO2 was lower (P < 0.05) and alveolo-arterial PO2 gradient (PAaO2) increased (P < 0.05). All animals revealed moderate pulmonary oedema (EVLW = 15.1 +/- 8.4 ml.kg-1) (P < 0.01) and a lower FRC. Mechanical ventilation with PEEP significantly improved oxygenation and FRC; however, DO2 was slightly lower than during IPPV (not significant). IRV elevated PaO2, FRC and DO2, since CO was not depressed when compared with IPPV. CONCLUSIONS. CPPV and IRV may induce a recruitment of collapsed or hypoventilated lung areas, which is more pronounced during CPPV. During both modes of ventilation, oxygenation was improved without apparent changes in EVLW. Haemodynamic performance was more impaired during CPPV, and no improvement of left ventricular function secondary to an elevated intrathoracic pressure was observed. Occlusion of the RIVA coronary artery typically induces an infarction of 35% of left ventricular muscle mass; however, non-ischaemic myocardium reveals an unchanged or increased contractility. Thus, a reduction of left ventricular preload secondary to CPPV mainly contributes to haemodynamic depression, which is less pronounced during IRV due to a lower peak inspiratory airway pressure and mean airway pressure. IRV may be useful for mechanical ventCntCo

Animals↗