Biomedical subjects

H E Refsum

Publications and source records attributed to H E Refsum.

At least 19 recordsLinked to original sources

PubMed2001

Excessive exercise ventilation in moderate left heart dysfunction. Influence of postural changes in central haemodynamics and blood gases.

To evaluate the relative importance of pulmonary congestion and peripheral hypoxia as causes for the excessive exercise ventilation in left heart dysfunction, seven patients with excessive ventilation and distinct left heart dysfunction during moderate exercise (LHD), and seven control patients with essentially normal exertional functions (CTR), had ventilation, central haemodynamics, arterial and mixed venous blood gases examined at rest and exercise, 32 W (25-40) in the LHD group and 44 W (33-49) in the CTR group, in lying and sitting positions. Change from lying to sitting exercise, led to fall in pulmonary artery wedge pressure (PAWP) from 31.0 +/- 5.5 to 8.8 +/- 5.0 mmHg in the LHD group, compared with from 13.7 +/- 1.0 to 2.1 +/- 2.4 mm Hg in the controls, while ventilation/O2 intake ratio (V/VO2) and physiological dead space/tidal volume ratio (VD/VT) showed a tendency to rise, from 36.3 +/- 8.8 to 39.2 +/- 7.4, and from 0.35 +/- 0.11 to 0.39 +/- 0.09, respectively, in the LHD group, and from 27.5 +/- 3.1 to 28.7 +/- 5.3, and from 0.19 +/- 0.09 to 0.21 +/- 0.12 in the controls. Mixed venous O2 tension (PvO2) showed a marked decline from 3.60 +/- 0.33 to 3.26 +/- 0.36 kPa in the LHD group, as compared with from 3.94 +/- 0.28 to 3.71 +/- 0.29 kPa in the controls, while the calculated physiologic shunt (Qs/Qt) suggested improved alveolo-arterial gas exchange. The data fit in with recent studies ascribing the excessive exercise ventilation to a combination of signals from hypoxia-induced changes, particularly in the exercising muscles, and augmented ergoreflex and central and peripheral chemoreceptor activity, partly to changes in the integrated control of ventilation and circulation, not to mechanisms related to pulmonary congestion.

Aged↗

PubMed2000

Response to changing plasma concentrations of isosorbide-bound NO2 during acute and sustained treatment with isosorbide dinitrate in patients with coronary artery disease.

BACKGROUND: The mechanisms behind development of tolerance to nitrate effects during sustained, asymmetric isosorbide dinitrate (ISDN) therapy are not fully understood. HYPOTHESIS: The study was undertaken to investigate the changes of the relationships between left ventricular (LV) function and plasma concentrations of ISDN and its vasoactive metabolites (2- and 5-ISMO) during acute and sustained, asymmetric ISDN therapy. METHODS: Left ventricular function and plasma concentrations of ISDN, 2- and 5-isosorbide mononitrates (P-ISDN, P-2- and 5-ISMO) were measured at rest and at supine exercise before and for 4 h after peroral 30 mg ISDN in 15 patients with coronary artery disease, all with initial exercise pulmonary artery wedge pressure (PAWP) > 25 mmHg. Seven patients were untreated (acute group), while eight received 30 mg ISDN b.i.d. for 2 weeks before the invasive study. P-ISDN and the concentration of available isosorbide-bound nitrate (NO2) in plasma (P-ISDN.2 + P-2-ISMO + P-5-ISMO) (P-NO2) were used as measures of the nitric oxide (NO) offer to the tissues. RESULTS: Throughout the study, after administration of medication, all plasma concentrations, in particular P-ISDN, were higher in the chronic than in the acute group. Peak P-ISDN was reached after 15 min in the chronic group and after 25 min in the acute group, while P-2- and 5-ISMO reached maximum only after 40 min in both groups. At rest, the full effect on PAWP was observed after 10 min in both groups, but at markedly higher levels of P-ISDN and P-NO2 in the chronic group. Afterward, no further changes in PAWP were observed. During exercise, 1 h after medication, PAWP and stroke index to PAWP ratio (SI/PAWP) were normal in both groups. Thereafter, at slowly declining P-NO2, PAWP rose and SI/PAWP declined toward the initial level in the chronic group, but remained unchanged in the acute group, in spite of higher P-NO2 and greater NO release in the former. CONCLUSIONS: Patients receiving sustained, asymmetric 30 mg ISDN b.i.d. dosing had the same immediate beneficial effects on LV function during exercise after a morning dose as did untreated patients. However, in spite of higher P-NO2 and higher rate of NO release during sustained treatment, the effects deteriorated gradually 2 to 3 h after medication. The changes in metabolism and/or distribution of isosorbide-bound NO2 may possibly be part of the tolerance induced by long-term treatment, even with asymmetric dosing.

Aged↗

PubMed1999

Effects of isosorbide dinitrate on electrocardiography, hemodynamics, and ventilation in patients with exercise-induced elevation of pulmonary artery wedge pressure.

BACKGROUND: The mechanisms underlying exertional hyperpnea in patients with coronary artery disease and transient left ventricular dysfunction are still not fully understood. HYPOTHESIS: The study was undertaken to investigate whether the ventilatory response to exercise reflects the effects of acute medical treatment of exercise-induced left ventricular dysfunction, and to evaluate mechanisms relevant to excessive exertional ventilation. METHODS: In 11 male patients, aged 65.2 +/- 6.0 years, all with pulmonary artery wedge pressure (PAWP) > 25 mmHg and ST depression > 2 mm during moderate supine exercise, ventilation (V), oxygen uptake (VO2), hemodynamics, electrocardiogram (ECG), and arterial and mixed venous blood gases were examined during supine rest and exercise, before and at hourly intervals after peroral intake of 30 mg isosorbide dinitrate (ISDN). Six similar patients were examined with the same protocol without ISDN administration and comprised a control group. RESULTS: Before administration of ISDN, exercise PAWP was 35.3 +/- 5.9 mmHg, ECG showed 2.77 +/- 1.06 mm ST depression, and V/VO2 was 31.8 +/- 4.8 l/l. One h after ISDN administration, exercise mean PAWP was 11.0 +/- 2.5 mmHg (p < 0.001), ST depression 0.59 +/- 0.8 mm (p < 0.001), whereas V/VO2 was unchanged, 30.1 +/- 5.3 l/l. Two h later, PAWP remained reduced and there were only minor ST depressions, while V/VO2 remained high. Exercise cardiac index (CI) and mixed venous oxygen tension (PvO2), initially 4.7 +/- 0.67 l/min/m2 and 3.54 +/- 0.35 kPa, respectively, remained at the same low level throughout the study. In the six nontreated patients, there were no significant changes in ST depression, exercise PAWP, or exertional ventilation. CONCLUSION: Isosorbide dinitrate treatment markedly improved exercise-induced left heart dysfunction, whereas excessive ventilatory response was unaffected, even after 3 h. Thus, measurements of the exercise hyperpnea did not properly reflect effective reduction of myocardial ischemia.

Aged↗

PubMed1999

Delayed respiratory response to exercise of short duration in patients with severe intermittent claudication due to bilateral atherosclerotic vascular disease: normalization after aorto-bifemoral bypass operation.

To investigate the respiratory response to exercise in patients with severe intermittent claudication, eight male patients, aged 57 years (range 43-73), with bilateral multi-segment atherosclerotic vascular disease, median maximum walking distance 50 m (range 20-200) and ankle-to-arm pressure index 0.4 (range 0.3-0.6), were studied before and after aorto-bifemoral bypass operation. Ventilation, CO2 output and O2 intake were recorded in the sitting position during 20 min of rest, 1 min of leg exercise on a bicycle ergometer [4.9 kJ (500 kpm)], and 20 min of recovery and rest. Before operation, maximal ventilation and CO2 output per minute were observed 2-4 min after cessation of work, while afterwards peak values were found during the work or the first minute of recovery. Pre-operatively, the extra ventilation and CO2 output during the work and recovery period and the recovery times of the ventilation and CO2 output per minute were markedly increased. Afterwards these values were clearly reduced towards normal. It is concluded that patients with severe intermittent claudication show a characteristic delay and prolonged rise in the respiratory response to exercise of short duration, which closely corresponds to the previously described pattern of outflow of hypoxia-generated metabolites from the exercising muscles. The pattern of respiratory response after operation reflects the fact that these patients also suffer from atherosclerotic heart dysfunction.

Adult↗

PubMed1998

Arterial and venous plasma catecholamines during submaximal steady-state exercise.

Arterial and venous plasma catecholamine responses to 15 min of cycling at 60% of maximal oxygen uptake were examined 11 times during exercise and recovery in nine young men. Intra-arterial blood pressure, heart rate and oxygen uptake were recorded continuously. All variables increased significantly during the initial 4 min, after which oxygen uptake, diastolic blood pressure and arterial plasma adrenaline showed no further increase. Heart rate and plasma noradrenaline, however, continued to increase, although significantly more slowly, and were closely correlated (r = 0.81, 95% CI 0.71-0.87), as were systolic blood pressure and heart rate (r = 0.78, 95% CI 0.71-0.87). Venous plasma adrenaline showed a steady increase during the whole exercise period and thus a different response pattern from arterial plasma adrenaline. In conclusion, arterial plasma catecholamines respond to steady-state exercise by a two-phase pattern paralleling the changes in arterial blood pressure and heart rate. Venous sampling does not reveal this association.

Adult↗

PubMed1997

Relationship between exercise hyperpnea, hemodynamics, and blood gases before and during glyceryl trinitrate infusion in patients with exercise-induced elevation of pulmonary artery wedge pressure.

BACKGROUND: The mechanisms underlying the excessive ventilatory response to exercise in patients with cardiac failure are still not fully understood. HYPOTHESIS: This study was undertaken to investigate the mechanisms behind exercise hyperpnea in patients with exercise-induced left ventricular dysfunction. METHODS: In 18 patients, aged 57-82 years, all with atherosclerotic lumbar aorta aneurysm and pulmonary artery wedge pressure (PAWP) > 25 mmHg during supine exercise, ventilation (V), central hemodynamics, and arterial and venous blood gases were examined during supine rest and exercise, before and during infusion of glyceryl trinitrate (GTN). RESULTS: Before GTN, exercise PAWP was 32.2 +/- 6.1 mmHg and V/V O2 was 33.8 +/- 7.7 l/l (130% of predicted). With GTN, exercise PAWP was markedly reduced to 15.3 +/- 3.8 mmHg (p < 0.001), whereas V/V O2 was only marginally reduced to 32.3 +/- 3.0 l/l (124% of predicted) (p < 0.05). Exercise physiologic dead space (VD/VT) declined from 0.31 +/- 0.16 to 0.26 +/- 0.17 (p < 0.05), while PaCO2 was reduced from 5.20 +/- 0.31 to 5.10 +/- 0.24 kPa (p < 0.05). PvO2 and cardiac output (CO), however, were unchanged below normal. CONCLUSION: The data show that exercise-induced hyperpnea was not substantially reduced by rapid normalization of PAWP and could not be related to preservation of normal PaCO2 in the presence of high VD/VT. The persistence of exercise hyperpnea and reduced PvO2 after GTN is consistent with augmented ventilatory stimuli from hypoxia-induced metabolic abnormalities in the skeletal muscles, or/and persistently reduced CO, due to changes in the integrated superior command of ventilation and circulation.

Aged↗

PubMed1997

Effect of extreme metabolic acidosis on oxygen delivery capacity of the blood--an in vitro investigation of changes in the oxyhemoglobin dissociation curve in blood with pH values of approximately 6.30.

OBJECTIVES: To determine the oxyhemoglobin dissociation curve in blood with pH of approximately 6.3 due to metabolic and superimposed respiratory acidosis, and to evaluate the oxygen delivery capacity of the blood under these circumstances. DESIGN: In vitro study. SETTING: A blood gas laboratory in a university institute for respiratory physiology. SUBJECTS: Heparinized normal human blood. INTERVENTIONS: The oxyhemoglobin dissociation curve was determined by measuring PO2, pH, PCO2, and hemoglobin oxygen saturation at 37 degrees C in mixtures of blood from two reservoirs, both prepared by titration with lactic acid to a pH of 6.3 during tonometry with gases containing 4.2% CO2 and high and low oxygen percentages, respectively. For determination of the effect of additional increases in PCO2, the reservoir blood thus produced was prepared by further tonometry with gases containing 12.8% CO2 and the same oxygen percentages. MEASUREMENTS AND MAIN RESULTS: With the same degree of lactic acidosis (blood lactate concentration of 52 mmol/L), the position of the oxyhemoglobin dissociation curve was the same for blood with PCO2 of 30 torr (4 kPa) and pH of 6.295 and for blood with PCO2 of 90 torr (12 kPa) and pH of 6.165. During tonometry with a gas with PCO2 of 30 torr (4 kPa) and PO2 of 20 torr (2.7 kPa) and addition of increasing amounts of lactic acid, leading to a stepwise change in pH from 6.7 to 6.0, hemoglobin oxygen saturation decreased with decreasing pH from 6.7 to 6.4, but remained the same at a pH of between 6.4 and 6.0. The measured rightward shift of the oxyhemoglobin dissociation curve at such a low pH was clearly less pronounced than that calculated using commonly applied equations, in particular, at the lowest pH. The beneficial effects of the rightward shift of the oxyhemoglobin dissociation curve on the estimates of extractable oxygen at a given venous PO2 decrease with decreasing pH, and disappear rapidly when the Pao2 is reduced below normal. CONCLUSIONS: The acidemia-induced rightward shift of the oxyhemoglobin dissociation curve does not increase further at a pH < 6.4, and is, at such extreme acidemia, less pronounced than calculated by the commonly used equations. To obtain optimal tissue oxygenation in patients with severe circulatory failure and extreme metabolic acidosis, Pao2 should be > 250 torr (> 33.3 kPa).

Acidosis, Lactic↗

PubMed1996

Hemodynamic time course of acute and chronic isosorbide dinitrate treatment at rest and during exercise in patients with stable ischemic heart disease.

HYPOTHESIS: The study was undertaken to establish differences between venous and arterial isosorbide dinitrate (ISDN) effects during acute and chronic treatment, hemodynamics at rest, and during supine exercise. METHODS: These effects were assessed invasively in 16 patients with stable ischemic heart disease before and at hourly intervals for 4 h after administration of peroral 30 mg ISDN. Eight patients were previously untreated (acute group), and eight were treated with 30 mg ISDN asymmetrically b.i.d. for two weeks (chronic group). RESULTS: Prior to ISDN administration, right atrial, mean pulmonary artery, pulmonary artery wedge, and mean arterial pressure (RAP, MPAP, PAWP, and MAP) rose from normal resting to pathologic values during exercise. One h after ISDN administration, all exercise pressures were normalized (p < 0.001). During the following 3 h, exercise RAP rose similarly in both groups (p < 0.01), while MPAP rose particularly in the chronic group (p < 0.001). Exercise PAWP and MAP, however, remained low in the acute group, but increased markedly in the chronic group (p < 0.01), particularly from the third to the fourth hour after ISDN. CONCLUSION: The daily, asymmetric administration of 30 mg ISDN b.i.d. maintained beneficial, anti-ischemic effects for 2 to 3 h after a morning dose of the drug, but thereafter attenuation of the effects occurred in the arteries but not in the veins.

Exercise Test↗

PubMed1995

Early hemodynamic effects at rest with acute and chronic isosorbide dinitrate treatment in patients with ischemic heart disease.

Asymmetric dosage regimens are used to circumvent development of nitrate tolerance and are believed to restore totally the hemodynamic responsiveness to an acute dosage of nitrates. This study assessed invasively the hemodynamics during supine rest before and for 50 min after peroral 30 mg isosorbide dinitrate (ISDN) in 16 patients with stable ischemic heart disease; 8 previously untreated patients (NT group) and 8 patients treated asymmetrically b.i.d. with 30 mg ISDN for 14 days prior to the invasive investigation (T group). Before initiation of treatment, both groups had identical mean arterial pressure (MAP) and heart rate (HR). On the day of invasive investigation, before intake of ISDN, MAP was higher in the T group but unchanged in the NT group. After the intake of ISDN, right atrial pressure (RAP), mean pulmonary arterial pressure, and pulmonary arterial wedge pressure declined markedly within 10 to 15 min in both groups, while MAP showed a more protracted decline, reaching a new level only after 25 to 30 min. In the NT group, HR accelerated markedly and remained elevated throughout the observation period, whereas in the T group HR showed no significant alteration after ISDN intake. At the end of the observation period, the cardiac index (CI) was definitely reduced in the NT group, but remained unchanged in the T group, while the systemic vascular resistance index was unchanged in the former and was clearly reduced in the latter. It is concluded that the fall in MAP in the NT group was solely due to a fall in CI, and that the decline in RAP and venous return in the NT group induced neurohumoral reflexes leading to a rise in HR and prevention of arterial dilation, whereas in the T group, already influenced by chronic treatment, such acute counterregulatory responses were markedly attenuated or absent.

Aged↗

PubMed1995

Autotransfusion after open heart surgery: the oxygen delivery capacity of shed mediastinal blood is maintained.

Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homologous transfusion during the last 15 years. The objectives of the present study were to investigate the oxygen delivery capacity of autotransfused shed mediastinal blood, compared to patient-blood, during cardiopulmonary bypass and in the postoperative period. Ten consecutive patients undergoing elective cardiac surgery were studied. Mediastinal shed blood was collected in the cardiotomy reservoir and retransfused during the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status algorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglycerate (2,3-DPG) concentration. Autotransfusion volume ranged from 450-1530 ml per patient (median 824 ml). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, respectively. There were no significant changes of 2,3-DPG concentration in the patient-blood during cardiopulmonary bypass or after autotransfusion compared to preoperative values. P50 for oxygen (3.6 and 3.6 kPa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in shed mediastinal blood (1h and 6h postoperatively) were not significantly different compared to patient-blood. The results demonstrate that the oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotransfusion.

2,3-Diphosphoglycerate↗

PubMed1995

Effects of recombinant human erythropoietin on fetal and adult hemoglobin in preterm infants.

In the present study we assess the effect of recombinant human erythropoietin (r-HuEpo) upon levels of fetal Hb (HbF) and adult Hb (HbA) in preterm infants. Twenty-eight "healthy," appropriate for gestational age infants with birth weights 900-1400 g entered the study at 3 wk of age. Fourteen infants were randomized to receive r-HuEpo, and 14 infants served as controls. Four controls and six r-HuEpo treated infants had been transfused before study start, whereas four control infants were transfused in the course of the study. The untransfused infants showed a high HbF/Hb ratio during the study with only a weak tendency to decline toward the expected time of delivery. The total Hb mass increased (p < 0.05) more in the r-HuEpo-treated infants than in the untreated, whereas the rise in HbF mass was similar in the two groups. After each transfusion, the HbF/Hb ratio reverted gradually to the ratio expected at the infant's postconceptional age. There was no difference in the production rate of HbF between r-HuEpo-treated infants and controls. The present data indicate that the HbF/HbA ratio in preterm infants is subject to the same programmed mechanisms which govern intrauterine erythropoiesis until term and that exogenous r-HuEpo does not influence this pattern significantly.

Adult↗

PubMed1994

[Physiotherapy in chronic obstructive pulmonary disease with and without mask training].

16 patients with chronic obstructive lung disease were randomized into two groups which were treated with physiotherapy for six weeks. In one group the treatment also involved using a respiratory training mask. Six patients in both groups completed the study. Both groups experienced an improvement for most parameters. The study showed that physiotherapeutic treatment with physical training improved the patients working capacity. However, the treatment with a mask gave no significant additional effect. 46 outpatients who were treated with a mask were asked later if they still used the mask. Only 28% used it regularly and 35% had stopped using the mask because they did not feel any effect.

Adult↗

PubMed1994

Influence of glyceryl trinitrate on venous and arterial effects of chronic, asymmetric isosorbide dinitrate treatment in patients with ischemic heart disease.

Asymmetric dosage regimes have been introduced to circumvent development of nitrate tolerance. This study assessed invasively the hemodynamics during supine rest and exercise before and after 4 weeks treatment with 30 mg isosorbide dinitrate (ISDN) or placebo asymmetrically b.i.d. in 14 randomized patients with stable ischemic heart disease in a double-blinded study. An intravenous infusion of glyceryl trinitrate (GTN) was used to assess possible nitrate tolerance. During the initial, medication-free exercise all patients had increased pulmonary arterial wedge pressure (PAWP) 31.4 +/- 5.56 mmHg (mean +/- SD), showing impaired left ventricular function, while mean arterial pressures (MAP) rose from 112 +/- 16.3 mmHg at rest to 141 +/- 15.9 mmHg during exercise. After 4 weeks ISDN treatment, mean exercise PAWP and MAP, 3 h after morning dose, were reduced to 22.4 +/- 7.09 mmHg and 127 +/- 18.2 mmHg, respectively. Before the ISDN treatment, GTN reduced exercise PAWP to 13.9 +/- 5.27 mmHg and MAP to 119 +/- 11.2 mmHg, whereas after 4 weeks ISDN treatment, the addition of GTN did not reduce exercise PAWP and MAP to the same low levels. Thus, the applied ISDN regimen improved the hemodynamics, but induced a definite, partial nitrate tolerance.

Aged↗

PubMed1992

A controlled multicenter clinical study of citalopram and placebo in elderly depressed patients with and without concomitant dementia.

A total of 149 patients in 7 centers in Denmark, Norway and Sweden entered a 6-week double-blind trial intended to assess the antidepressant effect and safety of citalopram vs placebo in depressed elderly patients (65 years of age or older) who might also suffer from somatic disorders and/or senile dementia. Results of ratings on the Hamilton Rating Scale for Depression, the Montgomery-Asberg Depression Rating Scale and the Clinical Global Impression Scale provided consistent evidence that the citalopram-treated patients improved more than the placebo-treated patients. Results of ratings on the Gottfries-Bråne-Steen dementia rating scale indicated that both cognitive and emotional functioning improved significantly more in the citalopram-treated subgroup of patients with dementia than in the placebo-treated subgroup.

Aged↗

PubMed1992

Lung function and radiographic signs of pulmonary fibrosis in oil exposed workers in a cable manufacturing company: a follow up study.

Thirty seven workers employed for at least three years in oil impregnation of cables during 1963-83 were followed up in 1990 to study the development of pulmonary fibrosis and consequences for lung function. They had been exposed to concentrations of mineral oil vapours of 50-100 mg/m3, and concentrations of oil mist of 0.5-1.5 mg/m3. All 29 living persons were traced. For each person one control matched for age, height, and smoking habits was selected. Among 25 workers followed up with radiographic studies, 10 cases of pulmonary fibrosis were found, by contrast with one case in the control group (p less than 0.01). Chest radiographs from 1979-80 and 1989-90 were reviewed. The profusion of small opacities increased in seven of 16 persons during 10 years without exposure. Seventeen workers had lung function tests. The bellows function (VC, FEV1, MVV) and lung volumes (TLC, RV) did not differ from those in the matched controls (p greater than 0.05), but the carbon monoxide transfer factor (TLCO) was decreased. The largest reduction of TLCO (1.5 mmol/kPa/min) was found among workers exposed for 10 years or more (p less than 0.05). Arterial blood gases were not affected at rest, but during maximum tread mill exercise, PO2 and HbO2 were reduced in exposed workers compared with controls, particularly among those exposed for at least 10 years (p less than 0.05). Exposure to low viscosity oil mist and vapour is the most plausible cause of the fibrosis. Unaffected bellows function, reduced TLCO, and decreased arterial blood oxygen during exercise is compatible with peribronchiolar fibrosis.

Adult↗

PubMed1990

Pulmonary function and gas exchange at rest and exercise in adolescent girls with mild idiopathic scoliosis during treatment with Boston thoracic brace.

Pulmonary function and gas exchange at rest and during and after standard exercise on bicycle ergometer were studied in 49 girls, aged 10 to 16 years (mean, 13.7), with untreated idiopathic scoliosis, before and with Boston thoracic brace, and after treatment for 3 weeks, reducing the thoracic curve angle from a mean of 32.4 degrees (range, 19-60 degrees) to 17.3 degrees (range, 8-33 degrees). The bracing led to marked decrease in lung volumes, below functions, and CO transfer factor, moderate rise in resting O2 intake, CO2 output and ventilation, and marked rise in ventilatory and O2 cost of exercise, probably due to increased dead space ventilation and O2 cost of breathing. However, repeated studies after 1 day without brace, 6 months after onset of bracing, showed no persistent deterioration of pulmonary function or disturbances of gas exchange, as compared with the pre-bracing state.

Adolescent↗

PubMed1990

Serum immunoreactive erythropoietin in children with acute leukaemia at various stages of disease--and the effects of treatment.

Most children with leukaemia are anaemic at diagnosis and at various times during treatment. Serum erythropoietin (EPO) was estimated in 27 children with acute leukaemia (n = 26) or lymphoma (n = 1) at diagnosis (n = 16), in relation to treatment with high-dose methotrexate (MTX, n = 11) or cytosine arabinoside (Ara-C, n = 8), and during oral maintenance therapy (n = 10). At diagnosis, in children with anaemia serum EPO was increased, and was inversely related to haemoglobin (Hb). After treatment with high-dose MTX, in some children serum EPO increased where Hb was unchanged or increased. After treatment with high-dose Ara-C, Hb declined, and serum EPO increased markedly in everyone. During oral maintenance therapy without significant anaemia, serum EPO was slightly increased in some children. In conclusion, children with leukaemia respond to anaemia with increased serum EPO concentration, but in relation to treatment with high-dose MTX and Ara-C, additional mechanisms may influence the EPO concentration.

Adolescent↗

PubMed1990

Pulmonary function and energy expenditure after marked weight loss in obese women: observations before and one year after gastric banding.

Pulmonary function and pulmonary gas exchange at rest, and during and after a standard exercise load of 500 kpm in 1 min on bicycle ergometer were studied in 34 women with severe, uncomplicated obesity, aged 37.8 (20-59) years, before and 1 year after gastric banding, resulting in a weight loss from 113.2 (84-156) to 81.7 (60-110) kg. Following the weight loss, TLC and VC rose from 93 and 94 per cent of expected to 98 and 101 per cent, respectively. FRC, ERV and FRC/TLC rose more markedly from 77, 64 and 83 per cent to 98, 109 and 99 per cent. IC fell from 108 to 99 per cent. RV and RV/TLV remained unchanged. FEV1.0 rose from 97 to 103 per cent, while MVV rose from 102 to 112 per cent, i.e. above normal. TLCO and PaCO2 remained unchanged, at 90 and 95 per cent, whereas PaO2 rose from 86 to 91 per cent. Resting O2 intake (VO2) decreased from 147 to 115 per cent of the expected for normal weight women, while VO2/BSA decreased from 113 to 99 per cent, the changes being greater than expected from commonly used formulas for prediction of metabolic rate. O2 cost of work (EO2) decreased from 142 to 105 per cent. Resting ventilation (V) declined from 136 to 113 per cent, while ventilatory cost of work (EV) decreased from 142 to 105 per cent. CO2 recovery time after work (CO2RT) decreased from 121 to 100 per cent, while the ratios CO2RT to EO2 and to extra CO2 output of work (ECO2) rose slightly. Thus, the loss of weight led to increased filling of the lungs, improved dynamic function, reduced ventilation/perfusion disturbances and greater than expected reduction of energy expenditure, both at rest and exercise. In the obese state there was no evidence of alveolar hypoventilation or impaired ventilatory control. The beneficial effect of weight reduction on the exertional dyspnea included a combination of marked reduction of ventilatory demands and moderate rise in ventilatory capacity.

Adult↗