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1.
The oxygen partial pressure may be measured cutaneously by directly heated Po2 sènsors attached to the surface of the skin. The use of a large-size cathode (diameter 4 mm) allows one to obtain an average Po2 value over a sufficiently large skin area.
The permeability of the membrane for oxygen has to be kept low to prevent a disturbance of the oxygen profile in the cutaneous tissue as a result of the oxygen consumption of the sensor. When using a 6 μm Mylar membrane, the current can be limited by the diffusion of oxygen through the membrane and is a measure of the arterialized cutaneous Po2.
One effect of using a membrane of low permeability is that the response time of the sensor is long (± 90% = ca 45 sec). The reliability of correctly reproducing cPo2 variations by sensors having different response times may be evaluated by determining the transfer function of the membrane which allows the calculation of the frequency characteristics for various membranes. The cutaneous tissue layer also acts as a filter for rapid Po2 fluctuations. The characteristic of this filter is essentially similar to that of a 'slow' membrane such as Mylar 6 μm. The information gained by using a 'rapid' membrane such as Teflon 13 μm is negligible.
In 490 comparative measurements in newborns performed with sensors heated to 44C, the correlation between arterial Po2 and cutaneously measured Po2 is significant (correlation coefficient = 0.934) and the regression line does not deviate significantly from the identity line. 相似文献
The permeability of the membrane for oxygen has to be kept low to prevent a disturbance of the oxygen profile in the cutaneous tissue as a result of the oxygen consumption of the sensor. When using a 6 μm Mylar membrane, the current can be limited by the diffusion of oxygen through the membrane and is a measure of the arterialized cutaneous P
One effect of using a membrane of low permeability is that the response time of the sensor is long (± 90% = ca 45 sec). The reliability of correctly reproducing cP
In 490 comparative measurements in newborns performed with sensors heated to 44C, the correlation between arterial P
2.
Heat from a transcutaneous oxygen electrode is transmitted locally to the blood beneath it causing a shift in the HbO2 dissociation curve. This increases the local PO2 , and allows a measurable PO2 , at the skin surface. The temperature effect on the HbO2 , curve must be accounted for in in vivo calibration of Ptco2 , data. To do this, the capillary blood temperature beneath the electrode must be known. A heat balance is written around the capillary blood with heat being conducted in from the electrode and carried out by two means: conduction to deep tissue; and transport away by the flowing capillary blood. The following equation is the steady state solution of the heat transport problem:
T8 = ±
where Z = ± = 0.17
T8 , = capillary blood temperature
T1 = electrode temperature
To = body temperature
ρ = blood density
P = cutaneous perfusion
δ = dermal capillary depth
k = thermal conductivity of skin
C± = heat capacity of blood
This solution shows the capillary blood temperature may be calculated if the T1 and To are measured and the physiologic constants in 2 are known. 2 is a dimensionless heat transport number which represents the relative importance of perfusion to conduction effects on the deterring T8 , and may be used as a data correlating parameter. Z = 0.17 is obtained using literature values for the physiological constants. This analysis used in conjunction with a mass transport analysis for oxygen will produce a theoretically based correlation scheme for in vivo calibration of heated transcutaneous oxygen electrodes. 相似文献
T
where Z = ± = 0.17
T
T
T
ρ = blood density
P = cutaneous perfusion
δ = dermal capillary depth
k = thermal conductivity of skin
C± = heat capacity of blood
This solution shows the capillary blood temperature may be calculated if the T
3.
《Acta anaesthesiologica Scandinavica》1978,22(S68):118-122
Transcutaneous Pco2 electrodes have been constructed and evaluated on adults and children. Glass pH and silver reference electrodes were used at 44–45C, with either circulating water and a copper jacket, or with internal electrical heating. The skin surface Pco2 at 44C is about 1.33 times Paco2 plus 3 mmHg when measured with electrodes calibrated in gas at 44C. Three temperature effects combine in this ratio: Heating raises blood Pco2 4.5%/C, skin metabolism adds about 3 mmHg, and the cooling of the electrode active surface by skin increases electrode reading. Response time to step changes of Paco2 was about 3 min to 63%, of which 1.2 min was sensor delay, the remainder skin C02 washout. It was found important to use ethylene glycol-water mixtures rather than water for electrolyte to avoid bubble generation and drift. Heat transfer through the pH glass electrode has been increased by enlarging the internal silver electrode to virtually fill the entire glass electrode. Time required for initial vasodilation and stabilization is similar to that of tcPo2 electrodes, and accuracy of determination of Paco2 appears to be better than ± 2 mmHg. 相似文献
4.
We use a Perkin Elmer MGA 1100 mass spectrometer modified for blood gas tension measurements to study transcutaneous measurements of oxygen, carbon dioxide, nitrogen and helium in normal subjects. We use an aluminum sampling chamber heated to 42–44C and connected to the mass spectrometer by about 2 m of stainless steel tubing. The sampling area of 5 cm2 is covered with a polytrifluoro-chloroethylene membrane 18 μn thick (Allied Chemical Co., Aclar 33C). The membrane is supported by a sintered stainless steel disc with a thermistor incorporated for measurement of "membrane" temperature. The chamber is heated with a printed circuit heater (Minco) and is temperature regulated by a servo circuit.
We have used the system to measure O2 , CO2 , N2 and He via the heated skin in four normal subjects, breathing air and then 100% oxygen. We also observed the response to a single breath of helium. Helium appears at the skin within 10–15 sec. The time constant of its disappearance is about 70 sec. The average uncorrected gas tensions which we obtained breathing air were 11.2 kPa for oxygen, 5.1 kPa for carbon dioxide and 67.1 kPa for nitrogen. The corresponding values breathing oxygen were 41.1 kPa for oxygen, 4.4 kPa for carbon dioxide and 13.1 kPa for nitrogen. 相似文献
We have used the system to measure O
5.
Desflurane increases brain tissue oxygenation and pH 总被引:3,自引:0,他引:3
Background Desflurane anesthesia can produce cerebral metabolic depression and increase cerebral blood flow. We evaluated the effect of desflurane on brain tissue oxygen pressure (PO2 ), carbon dioxide pressure (PCO2 ) and pH during neurosurgery.
Methods: Following a craniotomy, the dura was opened and a Paratrend 7 sensor, which measures PO2 , PCO2 , pH and temperature, was inserted into brain tissue. In 6 control patients in group 1, anesthesia was maintained constant with 3% end-tidal desflurane over 60 min, including a 30-min stabilization period. In group 2, 9 patients were ventilated with 3% desflurane under baseline conditions. After a 30-min stabilization period, baseline tissue gases and pH were measured and end-tidal desflurane was increased to 6% and then 9% for 15-min intervals. Mean arterial pressure (MAP) was maintained with intravenous phen-ylephrine.
Results: Under baseline conditions, cardiovascular and brain tissue measures were similar between the 2 groups. Increasing end-tidal desflurane from 3% to 9% produced burst-suppression EEG in all patients and significantly increased tissue PO2 and pH and decreased PCO2 . No parameters changed significantly in the control group during steady-state anesthesia.
Conclusion: These results show that 9% desflurane can improve brain tissue metabolic status before temporary brain artery occlusion if cerebral perfusion pressure is maintained. This may be particularly important in patients with symptoms of ischemia before surgery. 相似文献
Methods: Following a craniotomy, the dura was opened and a Paratrend 7 sensor, which measures PO
Results: Under baseline conditions, cardiovascular and brain tissue measures were similar between the 2 groups. Increasing end-tidal desflurane from 3% to 9% produced burst-suppression EEG in all patients and significantly increased tissue PO
Conclusion: These results show that 9% desflurane can improve brain tissue metabolic status before temporary brain artery occlusion if cerebral perfusion pressure is maintained. This may be particularly important in patients with symptoms of ischemia before surgery. 相似文献
6.
H. T. Versmold O. Linderkamp K. H. Stuffer M. Holzmann K. P. Riegel 《Acta anaesthesiologica Scandinavica》1978,22(S68):40-48
Four devices for transcutaneous Po2 (tcPo2 ) monitoring have been applied simultaneously in 16 infants. Both during a maximal change in Pao2 and during physiological Po2 variations, the in vivo response time of the electrodes did not show the differences observed in vitro.
We compared A, a prototype of the electrode by Huch, Lübbers and Huch (25 μm Teflon membrane); B, the commercial version of A by Hellige-Draeger (25 μm Teflon); C, the Radiometer TCM I oxygen monitor (25 μm polypropylene); and D, the Roche macrocathode electrode (6 μm Mylar), at 44C.
In vitro the 50% response times were 2.9 ( A ), 4.4 ( B ), 3.7 ( C ), and 7.4 ( D ) sec. The rates of tcPo2 changes at the midpoint of the response curves were 3.8 ( A ), 2.0 ( B ), 3.0 ( C ), and 1.7 ( D ) kPa/sec.
In vivo during a sudden change from hyperoxaemia (Fio2 1.0) to normoxaemia the respective rates were 0.6 ( A ), 0.8 ( B ), 1.1 ( C ) and 1.0 ( D ) kPa/sec. The in vivo 50% response times were 53.3 ( A ), 51.1 ( B ), 46.2 ( C ), and 45.3 ( D ) sec. The lag time between Pao2 and tcPo2 was about one third of this overall response time.
The response to more physiological variations of Pao2 (periodic breathing) was not different among the tested electrodes in terms of damping and of delay of the tcPo2 deflections. In a steady state the correlation of tcPo2 44C vs Pao2 was close ( r = 0.98) with all devices up to 6.1 kPa (456 torr). 相似文献
We compared A, a prototype of the electrode by Huch, Lübbers and Huch (25 μm Teflon membrane); B, the commercial version of A by Hellige-Draeger (25 μm Teflon); C, the Radiometer TCM I oxygen monitor (25 μm polypropylene); and D, the Roche macrocathode electrode (6 μm Mylar), at 44C.
In vitro the 50% response times were 2.9 ( A ), 4.4 ( B ), 3.7 ( C ), and 7.4 ( D ) sec. The rates of tcP
In vivo during a sudden change from hyperoxaemia (Fi
The response to more physiological variations of Pa
7.
Use of the Combitube for airway maintenance during percutaneous dilatational tracheostomy 总被引:2,自引:0,他引:2
The Combitube airway allows short-term ventilation during cardiopulmonary resuscitation and can be useful in the management of the difficult airway. In a prospective observational study we assessed its use during percutaneous dilatational tracheostomy (PDT). Twenty-one intensive care patients scheduled for elective PDT had their tracheal tube replaced by a Combitube airway retaining the same ventilator settings. Arterial blood gases, airway pressures, SpO2 and end-tidal CO2 were measured as were the transmural pressures exerted by the Combitube cuffs. Combitube placement was successful in 20 of 21 patients although adequate ventilation was possible in only 17 (85%). There was no significant change in P a O 2 , S p O 2 , end-tidal CO2 , P a CO 2 or mean airway pressure during Combitube ventilation. A high mean (SD) transmural pressure of 14.7 (5) kPa was exerted by the distal cuff. The Combitube provided a satisfactory alternative airway to the tracheal tube during performance of PDT in 85% of our patients. Potential problems associated with its use in intensive care patients are outlined. 相似文献
8.
R. G. HAHN L. RIDDEZ B. BRISMAR Å. STRANDBERG G. HEDENSTIERNA 《Acta anaesthesiologica Scandinavica》1997,41(4):485-491
Background: Inhalation of a gas mixture containing 50% nitrous oxide in oxygen (N2 O/O2 ) is widely used for pain relief in emergency situations, which may also be associated with blood loss. The aim of this study was to evaluate the haemodynamic effects of this gas mixture in normo- and hypovolaemic subjects.
Methods: Six healthy males were studied during inhalation of N2 O/O2 before and after withdrawal of 900 ml of blood. On each occasion, we measured systemic and pulmonary arterial pressures, cardiac output, blood gases, extravascular lung water, and the blood flow and oxygen consumption in the whole body, liver and kidneys.
Results: Inhalation of N2 O/O2 reduced the stroke volume and increased peripheral resistance. Oxygen uptake decreased in the liver (-30%) and in the whole body (-23%). Blood withdrawal reduced the pulmonary arterial and central venous pressures (-30 to -50%) and further decreased stroke volume and the blood flows to the liver and the kidney (-15%). The extravascular lung water tended to increase both during inhalation of N2 O/O2 and during hypovolaemia.
Conclusion: N2 O/O2 aggravated the hypokinetic circulation induced by hypovolaemia. However, the oxygen consumption decreased only during inhalation of N2 O/O2 . This opens up the possibility that the cardiodepression associated with N2 O/O2 is caused by a change in metabolic demands. 相似文献
Methods: Six healthy males were studied during inhalation of N
Results: Inhalation of N
Conclusion: N
9.
Pulmonary inflammatory mediators after sevoflurane and thiopentone anaesthesia in pigs 总被引:2,自引:0,他引:2
Takala RS Soukka HR Salo MS Kirvelä OA Kääpä PO Rajamäki AA Riutta A Aantaa RE 《Acta anaesthesiologica Scandinavica》2004,48(1):40-45
Background: Volatile anaesthetics have been shown to affect the release of pulmonary inflammatory mediators and exacerbate pulmonary injury after experimental aspiration. Thus, in theory, volatile anaesthetics may worsen inflammatory pulmonary injury and disease. We have previously described that no significant changes in alveolar ultrastructure are seen after sevoflurane anaesthesia. However, this does not exclude any possible physiological alterations. The aim of our study was to evaluate pulmonary inflammatory mediators in bronchoalveolar lavage (BAL) after sevoflurane and thiopentone anaesthesia in pigs with intact lungs.
Methods: Sixteen pigs were randomly selected to receive either a continuous thiopentone infusion (control group, n = 8) or sevoflurane (n = 8) at 4.0% inspiratory concentration (1.5 MAC) in air for 6 h. Bronchoalveolar lavage samples were collected at the end of the study to determine pulmonary inflammatory markers.
Results: Compared with thiopentone anaesthesia, significant increases in BAL leukotriene C4 (LTC4 ), NO3 -, and NO2 - levels were observed after sevoflurane anaesthesia. In addition, there was a significant decrease in total blood leukocyte count in sevoflurane-treated animals.
Conclusion: We conclude that sevoflurane increases pulmonary LTC4 , NO3 -, and NO2 - production in pigs, indicating an inflammatory response. 相似文献
Methods: Sixteen pigs were randomly selected to receive either a continuous thiopentone infusion (control group, n = 8) or sevoflurane (n = 8) at 4.0% inspiratory concentration (1.5 MAC) in air for 6 h. Bronchoalveolar lavage samples were collected at the end of the study to determine pulmonary inflammatory markers.
Results: Compared with thiopentone anaesthesia, significant increases in BAL leukotriene C
Conclusion: We conclude that sevoflurane increases pulmonary LTC
10.
O. SIGGAARD-ANDERSEN I. H. GØTHGEN N. FOGH-ANDERSEN 《Acta anaesthesiologica Scandinavica》1995,39(S104):7-13
In vitro monitoring is inherently invasive with discrete measurements on blood samples and the results are often delayed an hour or more when the analyses are performed in the central laboratory. The delay may be greatly reduced if the analyses are performed near the patient. In vivo monitoring may be non-invasive and may provide continuous real-time data but the accuracy usually does not match that of in vitro measurements. In vivo monitoring therefore finds its application in the detection of trends of change, and it is needed only for quantities that change rapidly and unpredictably and where a suitable therapeutic action is available. In critically ill patients, this applies to the arterial p O2 , p CO2 , and pH, and the mixed venous p O2 . Ideal in vivo monitoring techniques are not available for all these quantities. In the newborn, the arterial p O2 may be monitored with a transcutaneous p O2 electrode. In the adult, the arterial p O2 may be monitored indirectly by monitoring the arterial oxygen saturation with a pulse oximeter and the mixed venous p O2 by monitoring the mixed venous oxygen saturation with a catheter tip sensor. The arterial p CO2 may be monitored with a transcutaneous p CO2 electrode or by capnography, i. e., by monitoring the end-expiratory p CO2 . Other in vivo monitoring techniques such as gastric tonometry for the gastric mucosal pH and thoracic impedance measurement have found some routine application, whereas near-infrared spectrometry for oxy- and deoxyhaemoglobin in the brain, and magnetic resonance spectroscopy for tissue ATP are at the stage of research and development. 相似文献
11.
Yoshitoshi Kida Takashi Yamakawa Shuichi Iwasaki Nobuyuki Furusho Yoshihiro Kadowaki Seinosuke Iwata Yuji Iwashita Katsuhide Nishi 《Artificial organs》1995,19(6):511-518
Abstract: To evaluate the potential clinical usefulness of a modified hemoglobin, pyridoxalated hemoglobin polyoxyethylene conjugate (PHP), the hindlimb vascular bed was perfused with PHP solution while monitoring tissue oxygen tension (Pto2 ) in anesthetized dogs. The hindlimb region was perfused through the external iliac artery with a roller pump at a varying perfusion rate. Pto2 was measured using a Po2 -monitoring probe inserted into the gra-cial muscle. After surgical preparation for perfusion, the iliac arterial flow rate was 19.9 ± 5.6 ml/min, and baseline Pto2 was 38.4 ±1.3 mm Hg. Perfusion with autologous arterial blood with the pump increased Pto2 and perfusion pressure (PP) in a perfusion rate-dependent manner. Perfusion with PHP solution at 20 ml/min decreased Pto2 from the initial baseline level, but an increase in the flow rate to 40–55 ml/min restored or induced an elevation of Pto2 . Results demonstrated that PHP solution can deliver oxygen to local tissue and maintain tissue oxygen tension at the same level as autologous arterial blood at a high enough flow rate. 相似文献
12.
13.
A. Marni D. Forti A. Fulgenzi M. Corsi A. Cazzulani M.E. Ferrero 《Transplant international》1998,11(S1):S467-S471
Abstract We studied the modifications of blood T cell distribution following small-bowel allografting in rats under different experimental conditions. Group 1: ACI (RT1a ) rats were used as small-bowel donors for ACI × Wistar (RT1y ) F1 , hybrid rats (WAF1 ) in which graft-versus- host disease (GVHD) developed. Group 2: WAF1 rats were used as small bowel donors to ACI rats which developed rejection. Group 3: WAF1 rats received small bowel from ACI rats hyperimmunized for 10 days (by grafting them with WAF1 skin) and GVHD developed. Group 4: Wistar rats received small bowel from ACI rats hyperimmunized for 10 days (by Wistar skin) and bidirectional GVHD and rejection were assured. A second set of the same groups which were continuously administered with cyclosporin (15 mg/kg per day s.c. for 15 consecutive days) was also studied. Recipient peripheral blood lymphocytes, obtained at 7 and 15 days following small-bowel transplantation, were stained with monoclonal antibodies anti-rat CD4 and CD8 and then analyzed in an automated flow cytometer. A significant major reduction of CD4+ /CD8+ T cell ratios was shown in rats that developed simultaneous GVHD and rejection with respect to ungrafted rats. 相似文献
14.
Background: Both partial liquid ventilation (PLV) and tracheal gas insufflation are novel techniques for mechanical ventilation. In this study we examined whether PLV superimposed by continuous low-flow tracheal gas insufflation (TGI) offers any advantage to the blood gases and lung mechanics in normal-lung rabbits compared to the use of PLV only.
Methods: Eighteen anesthetized, paralyzed and mechanically ventilated rabbits were used. After obtaining a baseline PaCO2 value between 29 and 39 mmHg (3.9 and 5.2 kPa), the animals were assigned to three equal groups according to the ventilation they received - A group: PLV superimposed by TGI; B group: PLV only; and C group: continuous mandatory ventilation (CMV) superimposed by TGI. Serial arterial blood gases, pH and lung mechanics were measured.
Results: The animals in each group were hemodynamically stable. In the case of the A group, PaO2 continuously increased, and PaCO2 stabilized around 40.8±5.5 mmHg (5.4±0.7 kPa, mean±SD, NS). In the B group, the tendency for PaO2 to increase was not as definite; PaCO2 continuously increased from 35.2±2.3 mmHg (4.7±0.3 kPa) to 56.3±12.7 mmHg (7.5±1.7 kPa, P < 0.05) at the end of the experiment. In the C group, PaO2 and PaCO2 were stable during the observation period. The superimposition of TGI on PLV did not decrease the airway pressures compared to PLV alone.
Conclusion: In summary, continuous low-flow TGI superimposed on PLV can decrease and stabilize the PaCO2 elevation caused by the initiation of PLV. 相似文献
Methods: Eighteen anesthetized, paralyzed and mechanically ventilated rabbits were used. After obtaining a baseline PaCO
Results: The animals in each group were hemodynamically stable. In the case of the A group, PaO
Conclusion: In summary, continuous low-flow TGI superimposed on PLV can decrease and stabilize the PaCO
15.
H.J. PRIEBE G. F. E. NOLDGE K. ARMBRUSTER K. GEIGER 《Acta anaesthesiologica Scandinavica》1995,39(8):1088-1096
Supranormal oxygen (O2 ) transport may benefit critically ill patients. Catecholamines are clinically employed for this purpose. However, their effects on splanchnic haemodynamics and oxygenation are not well defined. The effects of dobutamine (DOBU), dopamine (DOPA), and noradrenaline (NA) on splanchnic blood flows (electromagnetic flow probes), O2 deliveries and uptakes (catheterisation of portal and hepatic veins) were studied in nine anaesthetised (ketamine/flunitrazepam), ventilated, paralysed, and laparotomised pigs. All three catecholamines (DOPA at 15 μg·kg-1 · min-1 , DOBU at 13 μg · kg-1 · min-1 , NA at 0.4 μg · kg-1 · min-1 ) significantly ( P <0.05) increased cardiac output and systemic O2 delivery. Only DOPA increased small intestinal and total hepatic blood flows, and O2 deliveries, and decreased O2 extractions. The same parameters did not change during DOBU. During NA, total hepatic blood flow and O2 delivery decreased, and hepatic O2 extraction increased. During all three catecholamines, small intestinal and total hepatic O2 uptakes did not change significantly. Whereas hepatic arterial blood flow decreased during both DOPA and NE, portal venous flow increased during DOPA. These data suggest that in the experimental model used splanchnic O2 supply and O2 reserve capacity appear improved by DOPA, unaffected by DOBU, and impaired by NA. 相似文献
16.
D. Parker D. Delpy E. O. R. Reynolds D. ST. Andrew 《Acta anaesthesiologica Scandinavica》1978,22(S68):33-39
Several possible methods for estimating and recording skin blood flow by thermal clearance are presented. The method chosen for trial with an O2 electrode was to thermoregulate an annular anode which covered the cathode, surrounding it like a heat shell, and to measure the cooling of the cathode by blood flow, by implanting a thermistor near the surface of the cathode. This device is far less affected by ambient temperature than is simple measurement of heating power in an uninsulated tcPo2 electrode. 相似文献
17.
F. J. Alvarez L. F. Alfonso E. Gastiasoro J. Lopez-Heredia A. Arnaiz A. Valls-i-Soler M.D. 《Acta anaesthesiologica Scandinavica》1995,39(7):970-974
Aim: To test the effect on pulmonary gas exchange and mechanics of multiple small doses of exogenous surfactant as an alternative to bolus delivery in experimental respiratory failure induced by lung lavage.
Methods: After anesthesia, tracheostomy and constant volume ventilation, respiratory failure was induced by lung lavage in 20 rats. Animals were randomly assigned to an untreated control group or two experimental groups. Equal total doses of modified porcine surfactant (200 mg ·kg-1 body weight,) were given by tracheal instillation, either as a single bolus or in four (50 mg·kg-1 b.w.) fractional doses at 10-min intervals. Arterial pH and blood gases, and peak inspiratory pressure (PIP) were measured.
Results: After lavage, a rapid decrease in arterial pH and PaO2 , and an increase in PaCO2 and PIP were observed in all animals. In both surfactant-treated groups, PaO2 increased after surfactant instillation, and remained significantly higher than controls throughout the experiment. Arterial pH was significantly higher and PaCO2 significantly lower only in the single bolus group. In the multiple dose group, these levels were similar to those of controls.
Conclusions: In surfactant-depleted rats with respiratory failure, instillation of four fractional surfactant doses did not result in the same enhancement on gas exchange and PIP, in the following 60 min, as same total dose given by a single bolus. 相似文献
Methods: After anesthesia, tracheostomy and constant volume ventilation, respiratory failure was induced by lung lavage in 20 rats. Animals were randomly assigned to an untreated control group or two experimental groups. Equal total doses of modified porcine surfactant (200 mg ·kg
Results: After lavage, a rapid decrease in arterial pH and PaO
Conclusions: In surfactant-depleted rats with respiratory failure, instillation of four fractional surfactant doses did not result in the same enhancement on gas exchange and PIP, in the following 60 min, as same total dose given by a single bolus. 相似文献
18.
Influence of age on circulation and arterial blood gases in man 总被引:1,自引:0,他引:1
L. Gunnarsson L. Tokics B. Brismar G. Hedenstierna 《Acta anaesthesiologica Scandinavica》1996,40(2):237-243
Background. Modem data on the influence of age on hemodynamic and blood gas data in healthy subjects are sparse, especially in middle aged or older subjects. Most measurements have been done in patients during major surgery or in intensive care when the patients have one or more failing organ systems. This study reports on hemodynamics, blood gases and blood volume in healthy patients prior to anesthesia and elective surgery.
Methods. A total of 116 subjects (92 males, 24 females) were investigated prior to anesthesia and elective surgery. No one had received any premedication or was taking regular medication. All subjects were in good physical condition, except for their surgical disease, and clinical examination and history did not reveal any sign of cardiopulmonary disease. Measurements were made of systemic and pulmonary vascular pressures, cardiac output, arterial blood gases and blood volume by131 I-Albumin distribution.
Results. Cardiac output, stroke volume, and blood volume correlated to body surface. Relating these variables to body size eliminated almost all differences between the male and female groups. These variables, as well as both systemic and pulmonary artery systolic vascular pressures, were affected by increasing age. Pulmonary capillary wedge and right atrial pressures were not influenced by age. PaO2 decreased with age from 14.0 kPa at 20 years to 11.3 kPa at 80, whereas PaCO2 was unaltered. No effect of light smoking was found on pulmonary circulation or arterial blood gases. Significant correlations were found between blood volume on the one hand and body size and age on the other hand, but not in regard to sex. 相似文献
Methods. A total of 116 subjects (92 males, 24 females) were investigated prior to anesthesia and elective surgery. No one had received any premedication or was taking regular medication. All subjects were in good physical condition, except for their surgical disease, and clinical examination and history did not reveal any sign of cardiopulmonary disease. Measurements were made of systemic and pulmonary vascular pressures, cardiac output, arterial blood gases and blood volume by
Results. Cardiac output, stroke volume, and blood volume correlated to body surface. Relating these variables to body size eliminated almost all differences between the male and female groups. These variables, as well as both systemic and pulmonary artery systolic vascular pressures, were affected by increasing age. Pulmonary capillary wedge and right atrial pressures were not influenced by age. PaO
19.
Pulmonary sympathetic denervation does not increase airway resistance in patients with chronic obstructive pulmonary disease (COPD) 总被引:1,自引:0,他引:1
H. Groeben A. Schwalen S. Irsfeld P. Lipfert H.-B. Hopf 《Acta anaesthesiologica Scandinavica》1995,39(4):523-526
Whether or not neural blockade of pulmonary sympathetic innervation is of relevance for airway resistance in patients with chronic obstructive pulmonary disease (COPD) is unknown. Accordingly we evaluated airway resistance during sympathetic blockade by high thoracic epidural anaesthesia in patients with COPD. Before and 45 min after thoracic epidural injection of bupivacaine 0.75% (6–8 ml; n=10) total respiratory resistance (oscillometry, Ros ), vital capacity (VC), forced expiratory vital capacity in 1 s (FEV1 , [% VC]), functional residual capacity (FRC; helium dilution method), and arterial blood gases were measured. Three additional patients received bupivacaine intravenously (1.2 mg . min-1 for 45 min), another three received saline epidurally. Sensory blockade covered segment C5 through T8 . As an indicator of widespread sympathetic blockade including the lungs, skin temperature increased significantly on thumb and little toe. Despite pulmonary sympathetic denervation Ros , FEV1 , and FRC remained unchanged, while VC decreased slightly, probably due to intercostal muscle blockade. Blood gases remained constant. Neither intravenous bupivacaine nor epidural saline evoked directional changes. Since, in contrast to β-adre-noceptor blockade, pulmonary sympathetic denervation did not increase airway resistance in patients with COPD, neural sympathetic blockade seems to be of no relevance for airway resistance in these patients. 相似文献
20.
P. N. le Souëf A. K. Morgan L. P. Soutter E. O. R. Reynolds D. Parker 《Acta anaesthesiologica Scandinavica》1978,22(S68):91-97
Transcutaneous oxygen tension (tcPo2 ) measured by two skin electrodes of different design, and arterial oxygen tension (Pao2 ) measured by an intravascular oxygen electrode, were continuously compared for periods of 6–27 h in 45 newborn infants with respiratory illnesses. One skin electrode (Dräger) had three micro-cathodes surrounded by a heated ring-shaped anode and the other (Roche) a large heated cathode. The electrodes were calibrated in vitro; 44C was found to be a suitable electrode temperature for the estimation of Pao2.
tcPo2 recorded by the electrode with the microcathodes estimated Pao2 reasonably accurately for 6 h without the necessity for re-siting. tcPo2 recorded by the electrode with the large cathode gave a similar estimate of Pao2 for 3 h, but then tcPo2 often fell relative to Pao2. This fall was probably caused by skin changes at the electrode site. Poor skin perfusion causing underestimation of Pao2 by tcPo2 could not be identified by a number of methods tried. 相似文献
tcP