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A Meier-Hellmann

Publications and source records attributed to A Meier-Hellmann.

64 records · Page 4Linked to original sources
PubMed1994

Prostacyclin in septic shock.

OBJECTIVE: Investigation of the hypothesis that the infusion of 10 ng/kg/min prostacyclin (epoprostenol) (PGI2) improves O2 uptake in patients with hyperdynamic septic shock. DESIGN: Prospective, single cohort design. SETTING: ICU, university hospital. PATIENTS: Fifteen postoperative patients with septic shock. INTERVENTIONS: Infusion of 10 ng/kg/min of PGI2 for 60 min. MEASUREMENTS: Complete hemodynamic profile with O2 transport-related variables (simultaneous measurements of VO2 from the respiratory gases and by cardiovascular Fick) and blood lactate levels before start of the PGI2-infusion and 60 min thereafter. MAIN RESULTS: Oxygen delivery increased significantly (14 percent) from its already high value, 750 +/- 238 to 852 +/- 214 ml/min/m2. The O2 extraction ratio remained unchanged. When VO2 was measured from the respiratory gases, it was unchanged. When VO2 was measured by cardiovascular Fick, it increased slightly (p < 0.05). CONCLUSIONS: We conclude that in this O2 challenge test with PGI2 in patients with septic shock, an increase in O2 delivery was not matched by an increase in VO2. We believe that the adequate conventional support of these patients may have prevented the PGI2 from revealing a "covert" O2 debt. The PGI2 test did not predict mortality by O2 supply dependency. The small increase in VO2 as calculated indirectly suggests a degree of mathematical coupling of O2 delivery and uptake.

Adult↗
PubMed1994

Influence of N-acetylcysteine on indirect indicators of tissue oxygenation in septic shock patients: results from a prospective, randomized, double-blind study.

OBJECTIVES: Deactivation of endothelium-derived relaxing factor due to an increased oxygen radical load during sepsis may contribute to an impairment in microcirculatory blood flow. We investigated whether treatment with the sulfhydryl donor and oxygen radical scavenger, N-acetylcysteine, would improve whole-body oxygen consumption (VO2), gastric intramucosal pH, and veno-arterial CO2 gradient (veno-arterial PCO2) during septic shock. DESIGN: Prospective, randomized, double-blind study conducted over 2 yrs. SETTING: Septic shock patients admitted to the intensive care unit. PATIENTS: Fifty-eight patients requiring hemodynamic monitoring (radial and pulmonary artery catheters) due to septic shock, were included in this study. All patients were examined within 72 hrs after the onset of sepsis. They were optimally resuscitated by conventional means with volume and inotropic agents, and exhibited stable clinical conditions (hemodynamic values, body temperature, hemoglobin, FIO2). INTERVENTIONS: A gastric tonometer was inserted to measure the gastric intramucosal pH. Subjects randomly received either 150 mg/kg of intravenous N-acetylcysteine or placebo over a 15-min period, then a continuous infusion of 12.5 mg/hr of N-acetylcysteine or placebo over approximately 90 mins. MEASUREMENTS: Infusion measurements were begun 60 mins after the beginning of infusion and lasted approximately 30 mins. The infusion was then discontinued and 2 hrs later the final measurements were taken. MAIN RESULTS: Basic patient characteristics (age, sex, Acute Physiology and Chronic Health Evaluation [APACHE] II scores, Multiple Organ Failure scores) did not differ significantly, nor did pre- and 2-hr postinfusion measurements differ between any of the groups. Thirteen (45%) patients responded (i.e., showed an increase in VO2 > 10%, reaching a mean of 19%) to the N-acetylcysteine infusion. The N-acetylcysteine responders also showed an increase in gastric intramucosal pH, a decrease in veno-arterial PCO2, an increase in oxygen delivery, cardiac index, stroke index, and left ventricular stroke work index, as well as a significant decrease in systemic vascular resistance in comparison to baseline. The N-acetylcysteine nonresponders, as well as the patients in the placebo group, did not show any significant changes in any of these variables. The N-acetylcysteine responders had a higher survival rate (69%) than the non-responders (19%) and were studied earlier after onset of sepsis (37 hrs) than the nonresponders (61 hrs). The only significant difference between the entire N-acetylcysteine group (which included responders plus nonresponders) and the placebo group was an increased VO2 in the entire N-acetylcysteine group during infusion measurements. CONCLUSIONS: N-acetylcysteine provided a transient improvement in tissue oxygenation in about half of the septic shock patients, as indicated by an increase in VO2 and gastric intramucosal pH and a decrease in veno-arterial PCO2. The higher survival rate in the N-acetylcysteine responders and the fact that half of the patients receiving N-acetylcysteine did not respond, suggests that, in some patients, sepsis irreversibly damages the microvasculature to the extent that N-acetylcysteine has no effect. If analyzed by intention to treat, the N-acetylcysteine did not produce effects that were significantly different from the placebo. Whether the N-acetylcysteine challenge was merely diagnostic or whether N-acetylcysteine can be effective in the treatment of sepsis deserves further investigation.

Acetylcysteine↗
PubMed1994

[Assessing the pH value of gastric mucosa with tonometry--general practice and potential clinical value].

The significance of the gastrointestinal region in the genesis and course of sepsis makes the monitoring of this region a fundamental importance in critical ill patients. The low-invasive assessment of gastric mucosal pH (pHi) seems to be able to detect a disturbed tissue oxygenation in the splanchnic region at an early stage. Animal studies have shown that there is a good correlation between pHi and directly measured pH. Splanchnic tissue hypoxia, induced in an experimental setting, is detectable by the pHi method. It has been shown in clinical studies that the patients' outcome depends on the first pHi, measured on admission to the ICU. An initial study has shown that patients with a pHi in the normal range on admission to the ICU had a better outcome if they were treated by a pHi-value orientated therapy. Nevertheless, some questions remain: There are problems with the practical use of this method, and it is unclear whether the pHi is really a marker for the whole splanchnic area. Further studies are required to determine the status of pHi in the clinical setting.

Animals↗
PubMed1993

[Hypertonic solutions in the intensive care unit].

The use of small volumes of hypertonic saline (HTS) 7.2-7.5% (small volume resuscitation) in combination with colloidal solutions has been proved to be of value in stabilizing oxygen transport in hemorrhagic shock. The specific effects of HTS lead to an improvement in tissue oxygenation by increasing the cardiac preload, decreasing the afterload and endothelial and interstitial edema within the microcirculation. This study investigates whether the use of HTS combined with hydroxyethylstarch (HAES) leads to a significant increase in the O2 delivery (DO2) and O2 consumption (VO2) in hyperdynamic critically ill patients. A total of 41 patients, 20 septic patients and 21 patients without sepsis were investigated. When a hyperdynamic circulation (DO2 > 700 ml/min/m2) was attained, 2-4 ml/kg 7.5% HTS in 6% HAES were infused over 15 minutes. In the septic patients this leads to a significant increase in the DO2 of 14% (p < 0.001). The VO2 (calculated from the cardiovascular Fick) increased by 7% (p < 0.05). The VO2 calculated from the respiratory gases increased by 4% (n.s.). This < 10% increase in VO2 does not seem to be due to a relevant tissue oxygen debt. This is supported by the fact that in the non septic group the DO2 and VO2 increased by the same extent, there was no significant difference between the two groups. Further there was an equal increase in the O2 extraction ratio of 10% (septic patients) and 9.5% (non septic patients). In both groups the mean plasma lactate levels before and 90 min after the HTS/HAES infusion were within normal range so that a wash-out phenomenon was not discernible.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical Care↗
PubMed1993

[O2 supply, O2 consumption and the pH value of the gastric mucosa. Indicators of tissue oxygenation].

The lack of a rise in global O2 consumption (VO2) after increased O2 supply (DO2) (negative O2-flux test) is an indication of adequate tissue oxygenation. We were interested in whether a negative O2-flux test precludes an improvement in regional tissue oxygenation. The pH of the gastric mucosa (pHi) is considered a sensitive marker for tissue hypoxia. Method. The study was approved by the ethics committee of our hospital. In 12 intensive-care patients with septic shock, gastric pHi was determined (Trip'TGS catheter, Tonometrics) in addition to measuring O2-transport-related parameters via invasive haemodynamic monitoring. Following the initial measurement, a further increase in the O2 supply via volume substitution was attempted in all already hyperdynamic patients with DO2 in the upper-normal range. Results. Volume substitution with 1.246 +/- 594 ml colloid resulted in an increase in pulmonary capillary wedge pressure from 14 +/- 2 mm Hg to 17 +/- 1 mm Hg (P < 0.01). All patients had an increase in DO2 from 755 +/- 192 ml/min.m2 to 846 +/- 236 ml/min.m2 (P < 0.05). There was no significant change in VO2, at 153 +/- 28 ml/min.m2 before and 156 +/- 35 ml/min.m2 after volume administration. However, pHi increased from 7.19 +/- 0.08 to 7.24 +/- 0.08 (P < 0.01). DISCUSSION AND CONCLUSION. The low pHi at the time of the initial measurement shows that regional tissue hypoxia may be present even in patients with an above-normal O2 supply > 600 ml/min.m2. Apparently, the lack of rise in global O2 consumption after increased O2 supply does not exclude a regional improvement in tissue oxygenation. The less invasive pHi measurement is an additional useful monitoring procedure for the optimisation of regional tissue oxygenation in critically ill patients.

Cell Hypoxia↗
PubMed1993

[Hepatic venous and mixed venous O2 saturation during catecholamine therapy in patients with septic shock].

Mixed venous O2-saturation (SvO2) reflects the ratio of global O2 supply to O2 consumption. However, in septic shock, there may be alterations in the ratio of regional O2 supply to O2 consumption, particularly in the splanchnic region. The aim of the study was therefore to investigate the relation between SvO2 and hepaticovenous O2-saturation (ShvO2) in septic shock with different catecholamine regimens. METHOD. Following approval of the ethics commission at our hospital, SvO2 and ShvO2 were measured simultaneously in 29 patients (7.5-F pulmonary arterial catheter). RESULTS. SvO2 and ShvO2 showed a considerable inter-individual difference with values between 1.3 and 36.9% and a mean of 14.7 +/- 9.3%. Alterations of ShvO2 were only tendentially reflected in alterations of the SvO2. Under different catecholamines SvO2 and ShvO2 showed the same changes but varying in extent (Table 1; Fig. 2). After switching the catecholamine therapy from dobutamine to epinephrine, SvO2 decreased only from 76.7 +/- 3.6 to 76.1 +/- 2.3 but ShvO2 from 61.4 +/- 8.1 to 54.2 +/- 10.3%. When the therapy was switched from dobutamine to norepinephrine, SvO2 decreased from 74.8 +/- 4.9% to 68.5 +/- 4.8%, ShvO2 decreased from 61.9 +/- 12.9% to 49.2 +/- 12.8%. When dopamine was added to norepinephrine, SvO2 increased from 68.6 +/- 4.3% to 73.6 +/- 4.4%, ShvO2 increased from 52.6 +/- 12.7% to 63.7 +/- 9.8%. When dopexamine was added to dobutamine, SvO2 increased from 74.6 +/- 4.5% to 76.9 +/- 2.5%, while ShvO2 increased from 57.6 +/- 11.5% to 58.8 +/- 13.4%. DISCUSSION AND CONCLUSION. The results presented show that SvO2 does not provide sufficient information about the venous O2 saturation of the splanchnic region. The intraindividually variable differences between SvO2 and ShvO2 during therapeutic interventions demonstrate that a selective alteration of blood supply to or O2 consumption of the splanchnic region has taken place, which is insufficiently reflected by the SvO2.

Dobutamine↗
PubMed1991

[Oxygen transport and tissue oxygenation in critically ill patients--value of volumes and vasoactive substances].

The primary function of the cardio-respiratory system is to meet the oxygen demands of the various organs and tissues and to remove metabolic wastes. The cellular O2 supply in the critically ill patient afflicted with severe infection, sepsis or ARDS is impaired not only by reduced O2 transport to the tissue due to myocardial depression caused by inadequate preloading and depressed contractility, but also by inadequate blood flow at the regional and microcirculatory levels. To obtain adequate tissue oxygenation despite derangements of the microcirculation, it is useful to aim for a hyperdynamic circulatory state that provides a supramaximal O2 transport. The best way to achieve this goal is first to optimize cardiac filling pressures, i.e. to the upper range of normal, and then to improve cardiac output using inotropic support. Only when the arterial pressure remains too low despite these measures is the use of vasopressors indicated.

Blood Volume↗
PubMed1990

[Early recognition of malignant hyperthermia using capnometry].

Although malignant hyperthermia is still a potentially fatal disease that was marked by a high mortality until recently, lasting damage to the patient can now be prevented by early diagnosis and treatment. The following case demonstrates the special value of capnometry in diagnosing this condition. A 34-year-old man admitted for oral surgery showed symptoms of malignant hyperthermia 5 h after induction of anesthesia. Neuroleptanalgesia had been conducted. The patient had received thiopental and fentanyl for induction of anesthesia and alcuronium and succinylcholine for intubation. The first symptom noticed was an elevation of the end-tidal pCO2 as monitored by capnometry. Additional symptoms, such as a pronounced rise in temperature, blood pressure, and heart rate did not develop until 20-25 min later. The end-tidal oxygen concentration decreased from 30 vol.-% to 26 vol.-%. The patient had to be ventilated with a volume of 25 l/min to keep end-tidal pCO2 under 6 kPa. Treatment with dantrolene was started immediately. Not until 3 h after the onset of the first symptoms did the patient's body temperature and the minute volume needed for ventilation return to normal. Postoperative laboratory findings showed only a slight elevation of creatine kinase and serum lactate. Myoglobin was not detected in serum or urine. This case indicates that capnometry permitted immediate adaptation of controlled ventilation to the patient's increased metabolic rate and early initiation of dantrolene treatment, thus preventing more severe disorders and possible consequences for the patient. Other studies have also suggested the special importance of capnometry. Since the patient refused to give his consent, the diagnosis could not be ascertained by muscle biopsy, and had to be based on symptoms.

Adult↗