Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recovery from inhalation anesthesia is often marked by the occurrence of postoperative tremor that resembles shivering, which is known to be associated with an increase in oxygen uptake (VO2), CO2 output (VCO2), and minute ventilation (VE). This study determined the time course of the ventilatory changes observed during the first hour of recovery from isoflurane anesthesia. Ten patients (ASA PS 1) scheduled for minor orthopedic surgery (knee arthroscopy) were included in this study. Anesthesia was induced with thiopental (5 mg/kg) and maintained with 70% N2O and isoflurane (1-2%) in oxygen, allowing spontaneous ventilation. In the recovery room, after N2O had been discontinued, patients were connected to a Beckman Metabolic measurement cart, which allowed a continuous monitoring of VE, VO2, VCO2, and PETCO2. Postoperative tremor was observed in all patients within 7.1 +/- 1.2 min (mean +/- SEM) after isoflurane discontinuation and was associated with a marked increase in the following: VO2, from 173 +/- 26 ml/min at the end of anesthesia to 457 +/- 88 ml/min; VCO2, from 149 +/- 18 ml/min at the end of anesthesia to 573 +/- 98 ml/min; and VE, from 6.8 +/- 0.7 l/min at the end of anesthesia to 16.6 +/- 2.8 l/min (values obtained 20 min after isoflurane discontinuation). In three patients during intense shivering, VO2, VCO2, and VE reached peak values higher than 800 ml/min, 1,300 ml/min and 30 l/min, respectively. This study shows that postoperative tremor following isoflurane anesthesia may be associated with prolonged and large increases in oxygen uptake, CO2 output, and minute ventilation.
 ...
PMID:Changes in ventilation, oxygen uptake, and carbon dioxide output during recovery from isoflurane anesthesia. 249 61

A low proportion of dietary calories as carbohydrate has been suggested for patients with chronic obstructive pulmonary disease, because oxidation of carbohydrate (CHO) compared to fat results in greater CO2 production (VCO2) and, at the same arterial PCO2 (PaCO2), higher alveolar and minute ventilation (VE) and increased dyspnea. We hypothesized that a low CHO-high fat diet, although reducing VCO2 and VE at rest, might result in only a small change in VCO2 and VE during exercise. Eight healthy volunteers were randomized to receive for 24 h either isocaloric diets containing 10% or 70% of total calories from CHO (remainder of nonprotein calories from fat). Measurements of VCO2, VE, and respiratory gas exchange ratio (R) were made at rest and during constant work rate cycle exercise below the anaerobic threshold. Five to seven days later, the alternate diet was given and the studies were repeated. At rest, mean VCO2 and R were significantly lower after the low CHO diet compared to the high CHO diet. Mean resting VE was less but not significantly (high CHO 9.6 [0.7] versus low CHO 8.7 [0.8] L/min, mean [SEM]). During exercise, mean VCO2 and R were significantly less after the low CHO diet, but mean VE was only slightly smaller and not significantly different between diets (high CHO 25.4 [1.1] versus low CHO 24.0 [1.0] L/min). The increase in VCO2 from rest to exercise was relatively independent of the substrate mix recently consumed, suggesting that the exercising muscles use stored muscle glycogen as substrate during short bouts of low-intensity exercise despite changes in substrate utilization by nonmuscle tissues at rest.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effect of altering the proportion of dietary fat and carbohydrate on exercise gas exchange in normal subjects. 249 33

To investigate the effects of the prostaglandin synthetase inhibitor, meclofenamate, on postnatal ventilation, we studied 11 unanaesthetised, spontaneously-breathing lambs at an average age of 7.9 +/- 1.1 days (SEM; range 5-14 days) and an average weight of 4.9 +/- 0.5 kg (range 3.0-7.0 kg). After a 30-min control period we infused 4.23 mg/kg meclofenamate over 10 min and then gave 0.23 mg/h per kg for the remainder of the 4 h. Ventilation increased progressively from a control value of 515 +/- 72 ml/min per kg to a maximum of 753 +/- 100 ml/min per kg after 3h of infusion (P less than 0.05) due to an increased breathing rate; the effects were similar during both high- and low-voltage electrocortical activity. There were no significant changes in tidal volume, heart rate, blood pressure, arterial pH or PaCO2, the increased ventilation resulted from either an increase in dead space ventilation or an increase in CO2 production. This study indicates that meclofenamate causes an increase in ventilation in lambs but no changes in pH of PaCO2. The mechanism and site of action remain to be defined.
 ...
PMID:Meclofenamate increases ventilation in lambs. 250 22

The build-up and clearance of halothane in rat brain have been measured non-invasively by 19F NMR spectroscopy using a surface coil placed on the intact scalp. When the halothane supply (3% in O2/N2O, 33/66%) was turned off, the 19F signal decreased exponentially to approximately 50% of the initial value, with a time constant, in normal rats, of 8.6 +/- 0.7 min (mean +/- SEM, n = 16), followed by a decay slower by at least one order of magnitude. The time constant of the rapid decay (tau), which was found to be specific for brain, was reduced in hypoxic/hypercapnic (5% O2/5% CO2) rats to 2.9 +/- 0.2 min (p = 0.001, n = 4), in rats infused with physostigmine (20 micrograms/kg/min i.v.) to 5.7 +/- 0.3 min (p = 0.005, n = 6) and increased in rats injected with pentothal (40 mg/kg i.p.) to 10.7 +/- 1.6 min (p = 0.2, n = 5). Based on the theory of exchange of inert gas at the lungs and tissues developed by Kety, the rapid exponential decay of the 19F signal was used to calculate relative cerebral blood flow (CBF). Assuming the cortical CBF in a normal rat to be about 130 mL min-1 100 g-1, the following CBF values (means +/- SEM) were obtained: controls 130 +/- 10, hypoxia/hypercapnia 390 +/- 59, hypercapnia 220 +/- 25, physostigmine 195 +/- 26, pentothal 105 +/- 23 mL min-1 100 g-1. These values are in good agreement with published values obtained with established methods.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Non-invasive determination of cerebral blood flow changes by 19F NMR spectroscopy. 251 56

The blood flow to the diaphragm, external and internal intercostal muscles, abdominal oblique muscles, and other rib-cage and abdominal muscles was measured, using radio-labelled microspheres, in 6 newborn lambs quietly breathing in air and during 3 different levels of CO2 induced hypercapnic hyperpnoea (inspired gas containing 4%, 5.5%, or 7% CO2). We also calculated the oxygen uptake of the diaphragm (VO2di). While the lambs were breathing air diaphragmatic blood flow (Qdi, 38.2 +/- 4.0 SEM ml.min-1.100 g-1) was similar to external intercostal muscle blood flow (Qei, 37.1 +/- 8.1 ml.min-1.100 g-1), and both were greater than internal intercostal muscle blood flow (Qii, 24.8 +/- 6.1 ml.min-1.100 g-1; P less than 0.05). During hyperpnoea Qdi, Qei, and Qii were augmented with Qdi equal to 200.1 +/- 12.2 ml.min-1.100 g-1 in 7% CO2 and Qei equal to 88.4 +/- 14.1 ml.min-1.100 g-1 in 7% CO2 (Qdi was greater than Qei, P less than 0.01). Qii was 40.7 +/- 5.6 ml.min-1.100 g-1 in 7% CO2 being less than Qdi (P less than 0.01) and Qei (P less than 0.05). The abdominal oblique muscles also had augmented flow in response to hyperpnoea. The level of hypercapnia that resulted in an augmentation of Qdi (5.5% inspired CO2) was lower than that which augmented Qei and Qii (7% inspired CO2). VO2di was linearly related to Qdi (r = 0.98). Our results suggest that in the newborn lamb the diaphragm is the dominant respiratory muscle in response to hypercapnia.
 ...
PMID:Blood flow to the respiratory muscles during hypercapnic hyperpnoea in the newborn lamb. 272 19

Isocapnic O2 equilibrium curves (O2ECs) were generated for whole blood of 4 adult burrowing owls (Athene cunicularia) using thin film techniques. At in vivo pHa (7.49 +/- 0.02; mean +/- 1 SEM) and 41 degrees C, the PO2 at half saturation (P50) was 42.3 +/- 0.8 Torr. CO2 and fixed acid (H+) Bohr slopes (delta log P50/delta pH) were -0.46 +/- 0.01 and -0.42 +/- 0.02, respectively, demonstrating a small specific CO2 effect. CO2 and H+ Bohr slopes were saturation-independent between 0.1 and 0.9 S. Hill plots for Athene blood were non-linear; the Hill coefficient (n) increased from 2.6 below 0.4 S to 3.4 above 0.6 S. Owl equilibrium data were accurately described by the equation: S = [(7.7 x 10(6]/(P4 + 44P3 - 108P2 + 3.5 x 10(4)P) + 1]-1. This complex O2EC shape may result from Hb heterogeneity; isoelectric focusing showed 4 isoHbs with a molar ratio of 9:1:1:1. This study revealed no apparent adaptations of Athene blood for hypoxic and hypercapnic conditions. We conclude that the observed blood O2 binding properties promote tissue O2 delivery during periods of surface activity. While occupying its burrow, the owl compensates for moderate alterations in inspired gas composition partly through increased ventilation.
 ...
PMID:Blood oxygen binding properties for the burrowing owl, Athene cunicularia. 274 25

Direct evidence for postganglionic sympathetic nerve activation to blood vessels supplying skeletal muscle was sought by recording from the peroneal nerve of 13 volunteers with a 5-mu tipped tungsten needle. Eight subjects breathed through an anesthesia face mask connected to a semiclosed anesthesia circuit for two consecutive 10-min periods while 25% and 40% nitrous oxide (N2O) was administered sequentially. Five subjects served as controls and breathed equivalent concentrations of nitrogen. Blood pressure and central venous pressure were recorded from radial artery and jugular vein catheters. Forearm blood flow was measured by venous occlusion plethysmography. Peroneal nerve recordings were amplified 100,000-fold and integrated for analysis of burst frequency. N2O did not significantly alter respiratory rate, end-tidal CO2 (mass spectrometry), and diastolic or central venous pressures but did produce small but significant increases in heart rate and systolic pressure compared to time-control (P less than 0.05). In contrast, N2O was associated with progressive, large increases in muscle sympathetic nerve activity (peak % delta = 69 +/- 22 burst/min [X +/- SEM]) and forearm vascular resistance (30 +/- 4%) and a nonsignificant increase in plasma norepinephrine levels. Thus, brief exposure to 25% and 40% N2O produces striking increases in sympathetic outflow to skeletal muscle in humans.
 ...
PMID:Nitrous oxide augments sympathetic outflow: direct evidence from human peroneal nerve recordings. 278 44

The mechanism of sustained awake hypercapnia in the obstructive sleep apnea syndrome (OSA) is unknown. Recent work has implicated coexisting chronic airflow limitation (CAL) as an important contributing factor. We approached this question by studying consecutive patients with both OSA syndrome and severe CAL in detail and comparing those with and without retention of CO2 while awake. Of 28 patients with both severe OSA (mean NREM apnea index = 48 +/- 9, SEM) and severe CAL (mean FEV1 = 1.07 +/- 0.07 L), 14 had persistent awake hypercapnia (mean PaCO2 = 50 +/- 1 mm Hg), and 14 were normocapnic (mean PaCO2 = 40 +/- 1 mm Hg). When separated according to their PaCO2 level, there was no difference in the apnea indices in both non-rapid-eye-movement (NREM) sleep, or rapid-eye-movement (REM) sleep, although the hypercapnic group had lower average levels of oxyhemoglobin saturation in both NREM (SaO2 = 77 +/- 2% versus 85 +/- 3%, p less than 0.05) and REM (SaO2 = 60 +/- 4% versus 82 +/- 3%, p less than 0.001) sleep. The mean values for FEV1, VC, lung volumes, and diffusing capacity for CO measured while awake did not differ. The hypercapnic group had lower awake PaO2 levels (p less than 0.001), were heavier (p less than 0.05), had narrower upper airway size on CT scan measurements (p less than 0.01), and gave a history of much heavier alcohol intake (p less than 0.05). Our results demonstrate that some patients with severe OSA and severe CAL can maintain normal awake arterial CO2 levels.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Obstructive sleep apnea with severe chronic airflow limitation. Comparison of hypercapnic and eucapnic patients. 281 88

The authors studied the effects of epidural sufentanil (0.75 microgram.kg-1) after urologic surgery in 15 children ranging in age from 4 to 12 yr, and in weight from 14 to 47 kg. The onset and duration of analgesia were 3.0 +/- 0.3 and 198 +/- 19 min, respectively (mean +/- SEM). Side effects included pruritus (3/15), nausea and vomiting (5/15), drowsiness (10/15), and urinary retention (1/11). No apnea was observed. Periosteal analgesia and ventilation were studied in eight of the children (mean age 8.6 +/- 0.8 yr). There was significant periosteal analgesia of the tibia (30, 60, 90, and 120 min after injection) and of the radius (60, 90, and 120 min after injection). Resting respiratory rate and tidal volume did not change during the study. Resting minute-ventilation decreased from 6.3 +/- 0.5 l.min-1 preoperatively to 5.6 +/- 0.6 l.min-1 (P less than 0.05) postoperatively, before epidural sufentanil injection; it did not decrease further after epidural sufentanil. Similarly, end-tidal CO2 tension increased significantly from 37.2 +/- 0.7 mmHg preoperatively to 39.9 +/- 1.2 mmHg (P less than 0.05) postoperatively, before epidural sufentanil; epidural sufentanil did not cause a further significant increase in end-tidal CO2 tension. The slope of the CO2 ventilatory response curve decreased significantly from 1.68 +/- 0.12 l.min-1. mmHg-1 preoperatively to 1.10 +/- 0.13 l.min-1.mmHg-1 (P less than 0.01) postoperatively. There were further significant decreases to 0.68 +/- 0.10 and 0.89 +/- 0.16 l.min-1.mmHg-1 30 and 60 min after epidural sufentanil.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Analgesia and ventilatory response to CO2 following epidural sufentanil in children. 289 31

The influence of respiratory-induced acid-base changes on the action of non-depolarizing muscle relaxants was investigated using the rat phrenic nerve-hemidiaphragm preparation. Changes in pH were induced by changes in the CO2 concentration aerating Krebs' solution. In the absence of muscle relaxants, an increase in CO2 from 5% to 7.5% decreased (P less than 0.01) indirectly elicited twitch tension by 5.4 +/- 0.7% (mean +/- SEM), while a decrease in CO2 from 5% to 2.5% increased (P less than 0.01) twitch tension by 2.3 +/- 0.7%. With a change in CO2 from 2.5% to 7.5%, partial neuromuscular blockade produced by d-Tc or vecuronium was augmented (P less than 0.01), while that produced by metocurine, pancuronium, or alcuronium was reduced (P less than 0.01). With the change in CO2 from 7.5% to 2.5%, the neuromuscular blockade produced by d-Tc or vecuronium was reduced (P less than 0.01), while that produced by metocurine, pancuronium, or alcuronium was augmented (P less than 0.01). Dose-response study showed that 2.5% CO2 shifted the dose-response curves for d-Tc and vecuronium to the right (P less than 0.01) from those with 5% CO2, whereas 7.5% CO2 shifted them to the left (P less than 0.05). In contrast, neither 2.5% CO2 or 7.5% CO2 significantly shifted the dose-response curves for metocurine or pancuronium from those with 5% CO2. Their dose-response curves with 2.5% CO2 were to the left, instead of to the right, of those with 7.5% CO2 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The influence of respiratory-induced acid-base changes on the action of non-depolarizing muscle relaxants in rats. 289 86


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>