PubMed Health⌕ Search

Biomedical subjects

K Reinhart

Publications and source records attributed to K Reinhart.

At least 19 recordsLinked to original sources
PubMed1991

Reversible decrease of oxygen consumption by hyperoxia.

The hemodynamic and metabolic effects of 90 minutes normobaric hyperoxia were studied in 20 critically ill patients (11 septic, 9 nonseptic) requiring mechanical ventilation with inspired O2 fraction (FIO2) less than 0.40. Thirty minutes after increasing the FIO2 to 1.0, arterial PO2 had increased from about 100 to about 400 mm Hg, and whole body oxygen uptake (VO2) was decreased 10 percent (p less than 0.05) due to an 18 percent decrease in O2 extraction ratio. During the subsequent 60 minutes of hyperoxia, there was no further significant change in VO2. Cardiac index did not change in hyperoxia, but it increased 10 percent (p less than 0.05) in recovery as systemic vascular resistance decreased. VO2 returned to baseline after 30 minutes recovery at original FIO2 due to increased O2 extraction as well as the increased cardiac output. The decrease in VO2 without a decrease in O2 delivery may reflect maldistribution of blood flow and functional O2 shunting to protect tissue from unphysiologically high PO2. While brief oxygenation is advisable before periods of hypoventilation, the present data suggest that hyperoxic ventilation in these patients with already adequate O2 delivery was counterproductive.

Bacterial Infections↗
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↗
PubMed1991

[The clinical assessment of tissue oxygenation. The significance of hemodynamic and oxygen transport-related parameters].

Adequate matching of the tissue O2 supply to the cellular O2 demands depends on the integrity of all components of the O2 transport system. The quality of O2 uptake by the lungs as well as O2 transport to the tissues can be assessed nowadays in the clinical setting. However, even if O2 uptake by the lungs and O2 transport to the tissues are normal cellular O2 supply may nevertheless be inadequate, if gas and substrate exchange are impaired on the tissue level. This may occur when nutritive blood flow is disturbed, as in patients with sepsis and ARDS. The hemodynamic monitoring parameters that are available in the clinical setting (i.e. systemic blood pressure, heart rate, cardiac filling pressures and art. blood gases) are only poor reflectors of the adequacy of tissue oxygenation. This review attempts to evaluate the extent to which the commonly measured hemodynamic variables relate to O2 transport and tissue oxygenation.

Hemodynamics↗
PubMed1990

Mutagenic and genotoxic activities of extracts derived from the cooked and raw edible mushroom Agaricus bisporus.

A. bisporus has been reported to be carcinogenic to mice [Toth et al. (1986) Cancer Res 38:177-180] and mutagenic in Salmonella typhimurium [Sterner et al. (1982) Mutat Res 101:269-281]. The effects of different heat treatments on the mutagenicity of raw, cooked (boiled) and fried A. bisporus extracts in the S. typhimurium test is reported. The spectrum of potential mutagenic activity of A. bisporus extracts was tested in vitro in Syrian hamster embryo cells for selective DNA amplification and in primary rat hepatocytes for DNA single-strand breaks. DNA single-strand breaks were also determined in liver cells of rats and micronuclei were measured in bone marrow cells of mice in vivo following oral application of A. bisporus extracts. It was shown that the complex A. bisporus extracts per se are not detectably mutagenic in S. typhimurium and that the previously observed increase in number of colonies per plate is probably due to a histidine artefact. No indication of genotoxicity was seen in the two in vitro assays with primary mammalian cells with two different end points. No evidence of in vivo genotoxic effects was observed in the rat liver cells. Finally, A. bisporus was not genotoxic in the micronucleus assay of mouse bone marrow cells in contrast to its previously reported carcinogenicity in mice.

Agaricus↗
PubMed1990

Optimal oxygen delivery in critically ill patients.

Standard hemodynamic support in septic shock is to increase pulmonary capillary wedge pressure to above 15 mmHg by volume replacement and to give inotropic support if the mean arterial pressure (MAP) is not adequate. In an attempt to decrease mortality in critically ill patients, oxygen delivery (DO2) was increased by switching inotropic support from dobutamine alone or in combination with norepinephrine to dopamine alone, or by adding dopexamine, prostacyclin, or hypertonic saline to the treatment. DO2 increased significantly in all patients, but the increase in DO2 was accompanied by only a 10% increase in oxygen consumption (VO2). The increase in VO2 was similar in survivors and nonsurvivors and in patients with and without septic shock. The results indicate that if adequate volume and inotropic support is provided for critically ill patients, the detectable oxygen debt is small and has little effect on patient outcome. When DO2 is adequate, factors other than a tissue oxygen deficit seem to determine patient outcome.

Cardiotonic Agents↗
PubMed1990

[Perioperative respiratory therapy and postoperative pain therapy].

Especially patients with preexisting bronchopulmonary diseases or those undergoing operations in the upper abdomen or thoracotomies are susceptible to post-operative pulmonary complications. All patients at risk should learn the prophylactic respiratory maneuvers preoperatively. Perioperative use of incentive spirometers, breathing exercises or IPPB seems to reduce the incidence of postoperative pulmonary complications. Opioids are used usually for postoperative pain management, but unfortunately they are given mainly as i.m. injections, although an i.v. administration would be far better. If given in an equipotent dose, nearly every opioid provides sufficient postoperative analgesia. Wide interindividual variation in the needed dose requires that opioids be titrated intravenously.

Combined Modality Therapy↗
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↗
PubMed1989

O2 uptake in bled dogs after resuscitation with hypertonic saline or hydroxyethylstarch.

Hemodynamic and metabolic variables were measured for the whole body and isolated hindlimb of anesthetized dogs during resuscitation from hemorrhagic shock, using a small volume of hypertonic saline or a larger volume of hydroxyethylstarch. Twelve dogs were bled and maintained at a mean arterial pressure (MAP) of 40 mmHg for 30 min. Six dogs were then infused with 7.5% NaCl in 5 ml/kg hydroxyethylstarch (HTS group), and six received 6% hydroxyethylstarch alone (HES group) in an amount to approximate the maximum MAP achieved with hypertonic saline. Hypertonic saline replacement was approximately 16% of shed blood volume compared with 66% for hydroxyethylstarch. With hypertonic saline, cardiac output returned to base line, but O2 delivery did not. Hydroxyethylstarch increased cardiac output above base line, and O2 delivery was near base line. O2 uptake with hydroxyethylstarch peaked at 40% above control at 10 min of resuscitation. Excess O2 uptake in recovery was higher than O2 deficit in hemorrhage with the HES group but not with the HTS group. In the isolated hindlimb, vascular resistance decreased rapidly on hypertonic saline infusion but reached similar levels at 10 min of resuscitation with both fluids. With progressive lowering of blood flow to the pump-perfused hindlimb, ability of limb muscle to extract O2 was the same for the HTS and HES groups. With hemodilution by volume replacement with acellular fluid after hemorrhage, a seemingly adequate cardiac output and arterial pressure may be underresuscitation if O2 delivery does not meet the increased O2 demand.

Animals↗
PubMed1989

Comparison of central-venous to mixed-venous oxygen saturation during changes in oxygen supply/demand.

Because central venous O2 saturation (superior vena cava, ScvO2) can be monitored with less patient risk than mixed venous O2 saturation (pulmonary artery, SvO2), we examined the correlations between SvO2 and ScvO2 over a broad range of cardiorespiratory conditions, including hypoxia, hemorrhage, and resuscitation in anesthetized dogs. The correlation coefficient (r) between SvO2 and ScvO2 in 179 simultaneously drawn blood samples from 22 dogs was 0.97. In another nine dogs, the two sites were continuously and simultaneously monitored with fiberoptic catheters; r was 0.96 with a mean difference of 3.7 +/- 2.9 percent (SD) saturation. In each dog the changes in ScvO2 closely paralleled the changes in SvO2. Although absolute values of ScvO2 are not sufficiently identical to SvO2 to calculate O2 uptake or pulmonary shunt precisely, close tracking of changes in the two sites across a wide range of hemodynamic conditions warrant further consideration of ScvO2 for patient monitoring of trends in O2 supply/demand.

Animals↗
PubMed1989

[The effect of pre-oxygenation on hemodynamics and oxygen consumption].

Pre-oxygenation is routinely used prior to anesthesia and intubation. In awake, premedicated patients scheduled for major aortic surgery we assessed the effects of breathing oxygen for 10 min via a loosely fitting face mask on hemodynamics and oxygen consumption (VO2). RESULTS. O2-breathing increased arterial PO2 to 51 +/- 13 kPa and decreased VO2 from 109 +/- 18 to 92 +/- 24 ml.min-1.m-2 (P less than 0.001 for both variables). This reduction of VO2 resulted from both a fall in cardiac index from 3.22 +/- 0.67 to 3.04 +/- 0.75 1.min-1/m-2 (P less than 0.05) and a decrease in arterio-venous oxygen content difference from 3.45 +/- 0.60 to 3.03 +/- 0.57 ml/dl (P less than 0.001). Systemic peripheral vascular resistance increased slightly from 1453 +/- 359 to 1538 +/- 383 dyne.s.cm-5.m-2 (P less than 0.05). CONCLUSIONS. These results indicate that an increase in F1O2 in patients without severe limitations of oxygen uptake by the lungs or oxygen transport to the tissues does not improve tissue oxygenation. We speculate that increased peripheral shunting acts to protect tissue PO2 during high arterial PO2 levels.

Aorta, Abdominal↗
PubMed1989

Effects of thoracic epidural anesthesia on systemic hemodynamic function and systemic oxygen supply-demand relationship.

The effects of thoracic epidural anesthesia (TEA) on total body oxygen supply-demand ratio are complex due to potential influences on both O2 delivery (QO2) and consumption (VO2). One hundred and five patients undergoing abdominal aortic surgery were randomly assigned to one of three groups to compare the cardiovascular and metabolic responses associated with (1) thoracic epidural anesthesia plus light general anesthesia (group TEA); (2) general anesthesia with halothane (group H); and (3) neuroleptanalgesia (group NLA). Values of cardiac index (CI) and QO2 were less intraoperatively in the TEA group than in the H or NLA groups, while VO2 values were similar. VO2 during recovery was greater in both the TEA and NLA groups than in the H group. Consequently the oxygen supply-demand ratio (QO2/VO2) was less in the TEA group throughout the perioperative period and about 30% below baseline values during early recovery. At comparable VO2, CI and mixed venous O2 saturation were always less in the TEA group than in the NLA group. Heart rate was slowest intraoperatively during TEA, and stroke work was less with TEA than with NLA. As cardiac filling pressure and systemic vascular resistance did not differ among the three groups, reduced adaptation of CI to tissue O2 needs during TEA was attributed to negative inotropic and chronotropic effects of the sympathetic blockade. We conclude that in patients undergoing abdominal aortic surgery, TEA has no apparent advantage over general anesthesia.

Anesthesia, Epidural↗
PubMed1989

[Catheter induced rupture of a proximal pulmonary artery caused by vigorous coughing in a spontaneously breathing patient].

A complication is occurred during insertion of a pulmonary artery catheter in a 73-year-old woman with class III NYHA cardiac failure. After easy insertion of the catheter, massive haemoptysis developed as the patient coughed while the balloon of the catheter was inflated. Despite prompt emergency measures, the patient did not survive. Autopsy revealed a 2.7-cm perforation of the proximal pulmonary artery with penetration into the right lower lobe bronchus. This complication and its prevention are discussed.

Aged↗
PubMed1988

[Monitoring of oxygen transport systems].

The main task of the cardiorespiratory system is to deliver enough oxygen (O2) to meet the metabolic requirements of the body. Of all metabolic substrates, O2 has the highest percentage of extraction at 25%, and O2-reserves are therefore exhausted within a few minutes. Arterial O2-content and cardiac output (CO) are the determinants of O2-delivery (DO2). O2-delivery in intensive care patients and during the perioperative period can be compromised by many factors, especially diminished O2-uptake in the lung, reduced hemoglobin content, and/or altered cardiac performance. The quality of arterial oxygenation can now easily be monitored noninvasively by pulse oximetry and arterial blood gas analysis. To calculate DO2, however, determination of cardiac output, O2-tension, O2-saturation, and hemoglobin is necessary. Routinely measured hemodynamic parameters such as heart rate, systemic arterial pressure, etc. only poorly reflect O2-transport to the tissues. O2-consumption (VO2), the best mirror of the actual metabolic activities of the tissues, can be measured either noninvasively by the difference between inspiratory and expiratory O2-concentrations in connection with minute ventilation or invasively using arterial-venous O2-content difference and CO, which requires pulmonary artery catheterization. VO2 determination by respiratory gas analysis is very difficult at a high or changing FiO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1988

[The effect of thoracic peridural analgesia on the cortisol and glucose response in surgery of the abdominal aorta].

UNLABELLED: It has been shown that the stress response to lower abdominal surgery can be inhibited by epidural analgesia (EA). But EA seems to have little influence on the stress reaction to major abdominal surgery. The purpose of our study was to find out whether EA is able to diminish the cortisol and glucose response to major transabdominal surgery. METHODS: 31 patients undergoing elective surgery of the abdominal aorta were subdivided at random into 3 different anaesthesia groups: 1. halothane anesthesia, 2. neuroleptanalgesia (NLA) and 3. thoracic EA with bupivacaine (0.5%) in combination with a light general anesthesia. Some patients of each group received an intravenous infusion of 5% glucose. Blood samples were drawn before anesthesia, after intubation, 5 times during surgery and at the end of the operation and were analysed for cortisol and glucose. During the early postoperative period, 1, 2 and 24 h after surgery, only cortisol was measured. RESULTS: Only the glucose levels of patients who received no carbohydrate-containing infusion fluids were used for evaluation of the stress response. In the halothane group, there was a significant increase of the mean cortisol and glucose levels after the start of surgery. No intraoperative elevations of blood glucose and cortisol were seen in the EA group. Patients of the NLA group showed no hyperglycaemia and only mild elevations of the cortisol levels during the intraoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗