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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

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↗

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↗

The HELLP syndrome.

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Analgesia, Obstetrical↗

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↗

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↗

Application of SHFJV for surgical procedures.

Using SHFJV in combination with the jet laryngoscope it is possible to ventilate patients for laryngeal surgery with out the necessity for any kind of endotracheal tube or catheters. This technique can also safely be applied in patients with underlying pulmonary or cardiac disease or in obese patients. Patients with laryngeal stenosis can be ventilated from above the stenosis eliminating the danger of barotrauma. The laser can be used at any time the surgeon desires without any additional protective measures. The SHFJV can be used for tracheobronchial stent insertion. Only in cases were the glottis can not be visualized through the jet laryngoscope sufficient ventilation is not ensured and therefore transtracheal high frequency ventilation is the technique of choice.

Adolescent↗

High frequency ventilation techniques in ARDS.

High frequency ventilation techniques are not applied as routine measures but are still regarded as lastditch efforts in treating patients with severe ARDS or with extensive bronchoplural fistula when conventional mechanical ventilation is not capable in providing sufficient gas exchange. High frequency ventilation techniques can be used in patients with septicemia or recent cerebral bleeding, which is a contraindication for ECMO, or in patients with increased ICP. We believe that high frequency ventilation techniques provide an important therapeutic tool in the treatment of pulmonary insufficiency since the hardware requirement is minimal and, after a brief explanation, the application is easy.

Adult↗

Platelet disorders in uraemia before and after haemodialysis under the influence of low dose aspirin.

Thrombocyte dysfunction and increased bleeding time (BT) are well documented in uraemic patients. However, these patients are frequently medicated with low dose aspirin (ASA) in order to maintain shunt patency and prevent cardiovascular events. Recently, life- threatening gastrointestinal haemorrhage in an uraemic subject taking low dose aspirin has been reported. In this work ASA related bleeding risk in uraemic patients and the effect of haemodialysis on their bleeding tendency was studied by measuring in vitro bleeding time (BT) using the Thrombostat 4000 in 34 uraemic patients on chronic haemodialysis compared to 50 healthy subjects. Our results indicate that low dose aspirin does not influence uraemic thrombopathia 8 to 10h after ingestion but seems to increase bleeding risk shortly after ingestion. Moreover, haemodialysis alters uraemic in vitro BT with regard to the time after ingestion of ASA.

Adult↗