Cardiovascular responses in paraplegic subjects during arm exercise

Summary The purpose of this study was to examine cardiovascular responses during arm exercise in paraplegics compared to a well-matched control group. A group of 11 male paraplegics (P) with complete spinal cord-lesions between T6 and T12 and 11 male control subjects (C), matched for physical activity, sport participation and age performed maximal arm-cranking exercise and submaximal exercise at 20%, 40% and 6070 of the maximal load for each individual. Cardiac output (Q _c) was determined by the CO₂ rebreathing method. Maximal oxygen uptake was significantly lower and maximal heart rate (f _c) was sigificantly higher in P compared to C. At the same oxygen uptakes no significant differences were observed inQ _c between P and C; however, stroke volume (SV) was significantly lower andf _c significantly higher in P than in C. The lower SV in P could be explained by an impaired redistribution of blood and, therefore, a reduced ventricular filling pressure, due to pooling of venous blood caused by inactivity of the skeletal muscle pump in the legs and lack of sympathetic vasoconstriction below the lesion. In conclusion, in P maximal performance appears to have been limited by a smaller active muscle mass and a lower SV despite the higher _c,max. During submaximal exercise, however, this lower SV was compensated for by a higherf _c and, thus at the same submaximal oxygen uptake,Q _c was similar to that in the control group.     

Construction and performance of a new catheter-tip oxygen electrode

A membrane-covered catheter-tip oxygen-electrode system is described, which gives a linear response in the P_o2 range of 0–350 mm Hg. The system is highly stable, free from drift and mechanically safe for application in man. This is accomplished by using a screw cap for fastening the membrane holder, thus preventing the loss of parts and making the electrolyte chamber really fluidtight. Insulation of the platinum wire with glass precludes the possibility of fluid-bridge contact with the silver anode beyond the measuring site at the tip.     

Pervasive developmental disorder behavior in adolescents with intellectual disability and co-occurring somatic chronic diseases

Evidence on the association between somatic chronic diseases in ID-adolescents and the full range of pervasive developmental disorder behavior (PDD behavior) is scarce. The aim of the present study is to assess the association between somatic chronic diseases in ID-adolescents and mild PDD behavior. We obtained data on 1044 ID-adolescents, aged 12–18, attending secondary schools in the Netherlands. Parents of the adolescents completed the Dutch version of the Children's Social Behavior Questionnaire (CSBQ) parent version, covering a wide range of PDD behavior, and questions about chronic diseases and background characteristics of their child. ID-adolescents with somatic chronic diseases showed more PDD behavior, in particular milder forms, than their peers without chronic diseases. In addition, ID-adolescents with somatic chronic diseases in combination with pervasive development disorders (PDD) and attention deficit hyperactivity disorder (ADHD) also showed more PDD behavior than their peers with only PDD/ADHD. Clinicians should be extra alert on PDD behavior, in particular the milder forms, in ID-adolescents when somatic chronic diseases are present. However, to strengthen our results about the relationship between somatic chronic diseases in ID-adolescents and PDD behavior studies are needed using both the CSBQ and standardized diagnostic instruments.     

Systemic circulation and cerebral oxygenation during head-up tilt in spinal cord injured individuals

OBJECTIVE: To compare tilt-induced alterations in cardiovascular homeostasis and cerebral oxygenation of spinal cord-injured (SCI) to able-bodied (AB) individuals. DESIGN: Subjects underwent 10 min supine rest followed by 10 min 70 degrees head-up tilt. The last 5 min of supine rest and head-up tilt were analyzed, provided a steady state existed. SUBJECTS: SCI individuals (n= 11), with lesions between C4 and T4, and AB individuals (n= 10), all males and balanced for age and weight. MAIN OUTCOME MEASURES: Calf circumference, mean arterial pressure (MAP), stroke volume, heart rate and cerebral oxygenated ([O2Hb]), deoxygenated ([HHb]) and total ([tHb]) haemoglobin concentration changes were measured. RESULTS: Head-up tilt evoked a greater fall in MAP (mean (SD): -9 (12) vs 2 (6) mmHg P=0.02) and stroke volume (-43 (12) vs -22 (10)%, P=0.005), and a greater increase in heart rate (27 (12) vs 18 (6) beats, P=0.04) in SCI than AB. Cardiac output decreased during head-up tilt in SCI but not in AB (-17 (15) vs 1 (15)%, P=0.01). The change in cerebral oxygenation ([HHb]: 3.9 (2.8) vs 2.8 (1.4) micromol x l(-1), P=0.1 and [O2Hb]: -6.1 (5.0) vs -2.1 (5.5) micromol x l(-1), P=0.1) was similar in SCI and AB. All variables mentioned showed a change significantly different from zero in both groups, apart from [O2Hb] in AB and [tHb] in both groups. CONCLUSION: SCI demonstrated a greater decrease of MAP and stroke volume with a similar decrease in cerebral oxygenation compared to AB. This suggests that although systemic circulation was less well regulated in SCI compared with AB, cerebral circulation in SCI was maintained as in AB.     

Experience with delayed repair of congenital diaphragmatic hernia during extracorporeal membrane oxygenation in a European center

In high-risk patients with congenital diaphragmatic hernia (CDH), we conducted a strategy of delayed repair following preoperative stabilization, including ECMO if necessary. From January 1991 to July 1992, preoperative ECMO treatment was delivered to 6 out of 14 high-risk patients with CDH. In this study, we report our experience with this policy of preoperative stabilization in six ECMO-treated patients in whom the diaphragmatic defect was repaired on ECMO. In all patients bleeding complications occurred. Three of the six ECMO-treated patients died, in two cases due to recurrent persistent pulmonary hypertension. Overall mortality was 43%.Conceptual aspects of our approach are discussed. Since the goals of our policy were not achieved, adjustments and renovations of the management protocol are discussed.On behalf of the ECMO Group     

Effects of repeated indomethacin administration on cerebral oxygenation and haemodynamics in preterm infants: Combined near infrared spectrophotometry and Doppler ultrasound study

The objectives of this study were to evaluate the effect of repeated indomethacin administration on cerebral oxygenation in relation to changes in cerebral blood flow velocity (CBFV) and other relevant physiological variables. Fourteen preterm infants with patent ductus arteriosus were studied during three subsequent indomethacin bolus administrations with intervals of 12 and 24 h. Changes in concentration of oxyhaemoglobin (cO₂Hb), deoxyhaemoglobin (cHHb) and oxidized cytochrome aa₃ (cCyt.aa₃) in cerebral tissue and changes in cerebral blood volume (CBV) were measured by near infrared spectrophotometry; changes in mean CBFV in the internal carotid artery were measured by pulsed Doppler ultrasound. Simultaneously heart rate, transcutaneouspO₂ andpCO₂, arterial O₂ saturation and blood pressure were measured. All variables were continuously recorded until 60 min after indomethacin administration. Within 5 min after each indomethacin administration, significant decreases in CBFV, CBV and cO₂Hb and cCyt.aa₃ were observed which persisted for at least 60 min, while cHHb increased or did not change at all. There were no changes in the other variables recorded. These data demonstrate that indomethacin administration is accompanied by a reduction in cerebral tissue oxygenation due to decreased cerebral blood flow. Therefore, low arterial oxygen content, either caused by low arterial O₂ saturation or by low haemoglobin concentration, may be a contraindication for indomethacin treatment in preterm infants.     

Hypoxia, the subsequent systemic metabolic acidosis, and their relationship with cerebral metabolite concentrations: An in vivo study in fetal lambs with proton magnetic resonance spectroscopy

OBJECTIVE: The relationship among decreased fetal arterial oxygen saturation, the subsequent systemic metabolic acidosis, and changes in cerebral metabolite concentrations in the fetal lamb brain was investigated by means of quantitative proton magnetic resonance spectroscopy. STUDY DESIGN: Fetal hypoxia was induced in 6 fetal lambs by gradual reduction of the oxygen supply to the anesthetized pregnant ewe. In vivo proton magnetic resonance spectroscopy was performed on the fetal lamb brain simultaneously with repeated measurements of fetal arterial oxygen saturation and acid-base balance. RESULTS: Proton magnetic resonance spectra showed metabolites such as inositol, choline compounds, creatine, and N-acetylaspartate. A signal for cerebral lactate was below the detection level under normoxic conditions and increased during hypoxia to indicate concentrations varying from 2.8 to 11.1 mmol/kg wet weight brain tissue. N -Acetylaspartate signals decreased during hypoxia, whereas signals of inositol, choline compounds, and creatine remained constant. CONCLUSION: These results support the view that fetal cerebral anaerobic metabolism in fetal lambs does not start under hypoxic conditions if the arterial blood pH is >7.28 or the base excess is >-8 mmol/L.     

1H-NMR spectroscopy of cerebrospinal fluid of fetal sheep during hypoxia-induced acidemia and recovery

The purpose of the study was to investigate the sequence of processes occurring during and after hypoxia-induced acidemia. We used proton nuclear magnetic resonance spectroscopy, which provides an overview of metabolites in cerebrospinal fluid (CSF), reflecting neuronal metabolism and damage. The pathophysiological condition of acute fetal asphyxia was mimicked by reducing maternal uterine blood flow in 14 unanesthetized pregnant ewes. CSF metabolites were measured during hypoxia-induced acidemia, and during the following recovery period, including the periods at 24 and 48 h after the hypoxic insult. Maximum values of the following CSF metabolites were reached during severe hypoxia (pH 相似文献   

Hypoxia in fetal lambs: a study with (1)H-MNR spectroscopy of cerebrospinal fluid

In fetal lambs, severe hypoxia (SH) will lead to brain damage. Mild hypoxia (MH) is thought to be relatively safe for the fetal brain because compensating mechanisms are activated. We questioned whether MH, leading to mild acidosis, induces changes in cerebral metabolism. Metabolites in cerebrospinal fluid (CSF) samples, as analyzed by proton magnetic resonance spectroscopy, were studied in two groups of seven anesthetized near-term fetal lambs. In group I, SH leading to acidosis with an arterial pH <7.1 was achieved. In group II, MH with an intended pH of 7.23--7.27 was reached [start of MH (SMH)], and maintained during 2 h [end of MH (EMH)]. During SH, choline levels in CSF, a possible indicator of cell membrane damage, were increased. Both during SH and at EMH, CSF levels of lactic acid, alanine, phenylalanine, tyrosine, lysine, branched chain amino acids, and hypoxanthine were increased compared with control values and with SMH, respectively. At EMH, the hypoxanthine CSF-to-blood ratio was increased as compared with SMH. These results indicate that prolonged MH leads to energy degradation in the fetal lamb brain and may not be as safe as assumed.     

Simultaneous near-infrared spectroscopy monitoring of left and right occipital areas reveals contra-lateral hemodynamic changes upon hemi-field paradigm

In this study we have shown that in humans it is possible to monitor non-invasively and simultaneously both hemispheres revealing cortical oxygenation changes in the occipital area in response to a contra-lateral hemi-field paradigm. A novel multi-channel near infrared spectroscopy approach with a high temporal resolution was used. The results confirm previous findings obtained by functional magnetic resonance imaging and positron emission tomography with the advantage to measure directly not only concentration changes in deoxyhemoglobin as measured by functional magnetic resonance imaging (MRI), but also in oxyhemoglobin with low cost instrumentation potentially useful to investigate the pathophysiology of vision.