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Biomedical subjects

M Zimpfer

Publications and source records attributed to M Zimpfer.

At least 55 records · Page 3Linked to original sources
PubMed1997

A rare presentation of thoracic aortic dissection as detected by transoesophageal echocardiography.

A case of atypical movement of the intimal flap (tear) during aortic aneurysm dissection is reported. Aortic dissection is caused by the sudden development of a tear in the aortic intima, opening the way for a column of blood driven by the force of the arterial pressure to enter the aortic wall, destroying the media and stripping the intima from the adventitia for variable distance along the length of the aorta. Echocardiographically, aortic dissection is characterized by separation of the normal single dominant echo from the aortic wall in the region of the dissection into two discrete echoes. The inner echo arises from the tunica intima, whereas the outer echo arises from the medial and adventitial structures external to the tear and it is possible to identify two lumens separated by an intimal flap within the aorta. The two echoes generally move in unison with one another, i.e. movement of the flap away from the true lumen during systole and recoil during diastole as the blood flows from true to false lumen. The dissection flap can also move inward during systole owing to the suction caused by high-velocity flow (Venturi effect), as shown in this case report. In any instances, motion of the intimal flap during the cardiac cycle is strong evidence of dissecting aneurysm.

Aged↗
PubMed1997

Biplane transoesophageal echocardiographic detection of myocardial ischaemia in patients with coronary artery disease undergoing non-cardiac surgery: segmental wall motion vs. electrocardiography and haemodynamic performance.

Intra-operative segmental wall motion abnormalities (SWMA) detected by transoesophageal echocardiography (TOE) have been shown to be a sensitive indicator of myocardial ischaemia. To determine the incidence and characteristics of segmental wall motion abnormalities and to relate these changes to perioperative myocardial ischaemia, biplane TEE, electrocardiogram (ECG) (II+V5) and pulmonary capillary wedge pressure (PCWP) were continuously monitored in 62 consecutive patients with ischaemic heart disease undergoing non-cardiac surgery. Short-axis view at mid-papillary level in transverse scan (T-scan) and long-axis in longitudinal (L-scan) two-chamber view were used for wall motion analysis. New segmental wall motion abnormalities were detected in 16 of 64 patients (25%) using biplane transoesophageal echocardiography. Monoplane transoesophageal echocardiography showed a sensitivity of 75% and a specificity of 100%, electrocardiogram two lead showed a sensitivity of 56% and a specificity of 98%, whereas pulmonary capillary wedge pressure had a sensitivity of 25%, and a specificity of 93% and pressure rate quotient (PRQ) < 1 demonstrated sensitivity of 19% and a specificity of 92% in the detection of myocardial ischaemia. It is concluded that the long-axis view of the left ventricle provides additional information for the detection of segmental wall motion abnormalities. Neither changes in haemodynamic performance nor in electrocardiography leads II and V5 match those of transoesophageal echocardiography for the identification of myocardial ischaemia.

Adult↗
PubMed1997

Validity of acoustic quantification colour kinesis for detection of left ventricular regional wall motion abnormalities: a transoesophageal echocardiographic study.

Transoesophageal echocardiography is a sensitive monitor for intraoperative myocardial ischaemia. Colour kinesis is a new technology for echocardiographic assessment of regional wall motion based on acoustic quantification. We have examined the feasibility and accuracy of quantitative segmental analysis of colour kinesis images to provide objective evaluation of systolic regional wall motion during the perioperative period using transoesophageal echocardiography (TOE). Two-dimensional echocardiograms were obtained in the transgastric short-axis and long-axis views in 60 patients with coronary artery disease undergoing noncardiac surgery. End-systolic colour overlays superimposed on the grey scale images were obtained with colour kinesis to colour encode left ventricular endocardial motion throughout systole. These colour-encoded images were divided into segments and compared with corresponding conventional two-dimensional images. Six hundred of a potential 720 left ventricular wall segments were of sufficient resolution for grading by experts; they diagnosed wall motion abnormalities in 61 of these segments by a conventional method. In comparing the conventional TOE method with colour kinesis, there were 60 true positives, 482 true negatives, 57 false positives and 1 false negative result. This yielded a sensitivity of 98%, specificity of 89%, positive predictive value of 51% and negative predictive value of 100%. Translational and rotational movement of the heart and papillary muscle interference were common problems accounting for false positive diagnoses. We conclude that colour kinesis provides a basis for objective and on-line evaluation of left ventricular regional wall motion which is a sensitive but non-specific method. It may be a useful aid for the less experienced because it can potentially direct the anaesthetist's attention towards specific segments.

Adult↗
PubMed1997

Effects of inhaled nitric oxide and extracorporeal membrane oxygenation on pulmonary hemodynamics and lymph flow in oleic acid lung injury in sheep.

OBJECTIVE: To compare the effects of inhaled nitric oxide (NO) and extracorporeal membrane oxygenation (ECMO) on oxygenation, hemodynamics, and lymphatic drainage in an oleic acid lung injury model in sheep. DESIGN: Prospective, randomized study. SETTING: Animal research laboratory. ANIMALS: Thirty female sheep, weighing 35 to 40 kg. INTERVENTIONS: Acute lung injury was induced by central venous injection of oleic acid (0.5 mL/kg body weight). A chronic lymph fistula had been prepared through a right thoracotomy 3 days before the experiment. Animals were assigned randomly to the NO group (n = 14) or the ECMO group (n = 16). When a lung injury score of > 2.5 was achieved, the animals were given NO in dosage increments of 2, 5, 10, 20, and 40 parts per million (ppm), or placed on ECMO with an FIO2 of 0.21 (ECMO-21) and then 1.0 (ECMO-100) at the oxygenator. Mechanical ventilator parameters were kept constant to isolate the effects of NO and ECMO on systemic and pulmonary hemodynamics, cardiac output, oxygenation parameters, lymph/plasma protein ratio, and lymph flow. Measurements and calculations were performed after 1 hr at each individual step of NO concentration or FIO2. MEASUREMENTS AND MAIN RESULTS: In the ECMO group, PVRI and MPAP did not change and were significantly different from the NO group. In the NO group, there was a dose-dependent decrease in venous admixture, maximal at 10 ppm NO and decreasing from 40 +/- 6% to 23 +/- 10% (p < .05). This decrease was significantly different from the ECMO group, where there was no change. There was a significant increase in PaO2/FIO2 in the NO group, maximal at 10 ppm NO (84 +/- 11 to 210 +/- 90, p < .05), but a greater increase in PaO2/FIO2 on ECMO-21 (81 +/- 14 to 265 +/- 63) and a further increase on ECMO-100 (398 +/- 100) (p < .05). The lymph/plasma protein ratio remained unchanged in both groups after induction of lung injury by oleic acid. However, lymph flow decreased by 11 +/- 6% in the NO group, whereas it increased by 14 +/- 17% in the ECMO group (p < .05). CONCLUSIONS: In an oleic acid-induced sheep model of acute lung injury, there were significant differences between the effects of NO and ECMO on acute pulmonary hypertension, hypoxemia, hypercarbia, and lymph flow. NO significantly decreases pulmonary hypertension, whereas pulmonary hemodynamics were not substantially affected by ECMO. Both interventions reversed hypoxemia, but ECMO did so to a greater degree, and only ECMO improved hypercarbia. Only NO decreased lymph flow, possibly as an effect of decreased microvascular filtration pressure. This study did not attempt to evaluate the impact of these interventions on ventilatory requirements, barotrauma, or outcome. However, this model suggests that NO therapy may moderate pulmonary hypertension and improve lymph flow in acute lung injury. Clinical studies are needed to assess whether NO therapy might be beneficial in treatment of severe acute lung injury in older children and adults.

Administration, Inhalation↗
PubMed1997

Sevoflurane in paediatric anaesthesia.

Sevoflurane is a potent inhalational agent, combining several advantages of specific interest in paediatric anaesthesia. Rapid and smooth induction, a safe cardiovascular profile, rapid emergence and a short postoperative recovery with minimal side effects are ideal characteristics of this agent for the use in paediatric anaesthesiology. The apparent improvement in management should not obscure the fact that sevoflurane in higher MAC should be used with caution in renal impairment. For the future world of our children, the lack of chlorine in the structure makes sevoflurane theoretically less ozone-depleting than halothane and isoflurane, a substance contributing to environmental protection.

Air Pollutants↗
PubMed1997

The HELLP syndrome.

Explore the source record for details and available documents.

Analgesia, Obstetrical↗
PubMed1996

Transoesophageal echocardiographic assessment of mitral and aortic valve function during cardiopulmonary resuscitation.

There has been controversy over whether forward blood flow during closed-chest cardiopulmonary resuscitation (CPR) is generated by a general increase in intrathoracic pressure (chest-pump theory) or by creating atrioventricular gradients that close the mitral valve and open the aortic valve during thoracic compression (cardiac pump theory). The crucial issue is the position of the mitral valve during the downstroke of chest movement. Questions remain over the actual mechanics of mitral and aortic valve function. This report describes an intraoperative cardiac arrest followed by CPR during which routinely instituted two-dimensional transoesophageal Doppler echocardiography enabled study of the motion of the valves of the left heart and the transmitral blood flow.

Aged↗
PubMed1996

A new scoring system, using Doppler transmitral diastolic measurement, identifies transient myocardial ischaemia.

In patients with acute transient myocardial ischaemia, changes in left ventricular filling produce alterations in transmitral diastolic flow velocity and isovolumic relaxation time. In this study a scoring system derived from isovolumic relaxation time and indices from transmitral flow velocity was used to evaluate perioperative transient myocardial ischaemia. Fifty three patients with known coronary artery disease or at risk were studied. Ischaemic events were assessed using Doppler transoesophageal echocardiography midoesophageal left ventricular four-chamber view planes. Diastolic Doppler ratios of peak early to atrial peak (E/A), deceleration time, deceleration rate and isovolumic relaxation time were scored using standard methods. An evaluation of peri-operative ischaemic events could be important for patients with a non-ischaemic cause for abnormal segmental wall motion, as the use of a two-dimensional scoring system has limitations. Acute changes in the Doppler ratio of peak early to atrial peak must be interpreted cautiously during surgery. Diastolic dysfunction commonly occurs during ischaemia and recognition of this may alter the approach to monitoring as well as to treatment.

Adult↗