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At least 883 records · Page 49Linked to original sources
PubMed1999

Waste anaesthetic gases induce sister chromatid exchanges in lymphocytes of operating room personnel.

Genotoxicity related to waste anaesthetic gas exposure is controversial. We have investigated the frequency of sister chromatid exchanges in peripheral lymphocytes of operating room personnel exposed to trace concentrations of isoflurane and nitrous oxide. Occupational exposure was recorded using a direct reading instrument. Frequencies of sister chromatid exchanges were measured in lymphocyte cultures of 27 non-smokers working in the operating room and 27 non-smoking controls. Personnel were exposed to an 8-h time-weighted average of nitrous oxide 11.8 ppm and isoflurane 0.5 ppm. After exposure, sister chromatid exchange frequency was increased significantly (mean 9.0 (SD 1.3) vs 8.0 (1.4) in exposed and control personnel, respectively) (P < 0.05). We conclude that exposure to even trace concentrations of waste anaesthetic gases may cause genetic damage comparable with smoking 11-20 cigarettes per day.

Adult↗
PubMed2001

Viscosity and density of common anaesthetic gases: implications for flow measurements.

Although viscosity (mu) is a crucial factor in measurements of flow with a pneumotachograph, and density (rho) also plays a role in the presence of turbulent flow, these material constants are not available for the volatile anaesthetic agents commonly administered in clinical practice. Thus, we determined experimentally mu and rho of pure volatile anaesthetic agents. Input impedance of a rigid-wall polyethylene tube (Zt) was measured when the tube was filled with various mixtures of carrier gases (air, 100% oxygen, 50% oxygen+50% nitrogen) to which different concentrations of volatile anaesthetic inhalation agents (halothane, isoflurane, sevoflurane, and desflurane) had been added. Mu and rho were calculated from real and imaginary portions of Zt, respectively, using the appropriate physical equations. Multiple linear regression was applied to estimate mu and rho of pure volatile agents. Viscosity values of pure volatile agents were markedly lower than those for oxygen or nitrogen. Clinically applied concentrations, however, did not markedly affect the viscosity of the gas mixture (maximum of 3.5% decrease in mu for 2 MAC desflurane). In contrast, all of the volatile agents significantly affected rho even at routinely used concentrations. Our results suggest that the composition of the carrier gas has a greater impact on viscosity than the amount and nature of the volatile anaesthetic agent whereas density is more influenced by volatile agent concentrations. Thus, the need for a correction factor in flow measurements with a pneumotachograph depends far more on the carrier gas than the concentration of volatile agent administered, although the latter may play a role in particular experimental or clinical settings.

Anesthetics, Inhalation↗
PubMed1990

Analysis of low molecular weight hydrocarbons including 1,3-butadiene in engine exhaust gases using an aluminum oxide porous-layer open-tubular fused-silica column.

A method for the quantitative analysis of individual hydrocarbons in the C1-C8 range emitted in engine exhaust gases is described. The procedure provides base-line or near base-line resolution of C4 components including 1,3-butadiene. With a run time of less than 50 min, the light aromatics (benzene, toluene, ethyl benzene, p- and m-xylene, and o-xylene) are resolved during the same analysis as aliphatic hydrocarbons in the C1-C8 range. It is shown that typical 1,3-butadiene levels in engine exhaust are about 5 ppm at each of two engine conditions. Aromatic hydrocarbon levels show a dependence on engine operating conditions, benzene being about 20 ppm at high speed and about 40 ppm at idle.

Aluminum Oxide↗
PubMed1982

Exposure to anaesthetic gases and spontaneous abortion: response bias in a postal questionnaire study.

A postal questionnaire study on anaesthetic gas exposure and miscarriage rate was performed among women who worked or had previously worked in a Swedish hospital. Results were evaluated in relation to age, smoking habits, work site at the first trimester of pregnancy and clinical accuracy of the reported data. An important part of the study was the collection of information on pregnancies among non-respondents. A higher, although non-significant, miscarriage rate was reported among women who had worked in areas with high exposure during the first trimester compared to unexposed women. A selection was found among the non-respondents with respect to both working site during pregnancy and outcome of pregnancy. All women suffering a miscarriage while working at sites with exposure to anaesthetic gases reported their work site and miscarriage, while one third of all miscarriages occurring to women who were not exposed during pregnancy were not reported in the questionnaire.

Abortion, Spontaneous↗
PubMed1998

Substantial changes in arterial blood gases during thoracoscopic surgery can be missed by conventional intermittent laboratory blood gas analyses.

UNLABELLED: Substantial and clinically relevant changes in arterial blood gases are likely to occur during thoracoscopic surgery with one-lung ventilation (OLV). We hypothesized that they may be missed when using the conventional intermittent blood gas sampling practice. Therefore, during 30 thoracoscopic procedures with OLV, the sampling intervals between consecutive intermittent laboratory blood gas analyses (BGA) were evaluated with respect to changes of PaO2, PaCO2, and pHa ([H+]) using a continuous intraarterial blood gas monitoring system. Frequency and timing of BGA were based on the clinical judgment of 16 experienced anesthesiologists who were blinded to the continuously measured values. Extreme fluctuations of PaO2 (37-625 mm Hg), PaCO2 (27-56 mm Hg), and pHa (7.24-7.51) were observed by continuous blood gas monitoring. During 63% of all sampling intervals, PaO2 decreased >20% compared with the preceding BGA value, which remained undetected by intermittent analysis. In 10 patients with a continuously measured minimal PaO2 value < or = 60 mm Hg, the preceding BGA overestimated this minimal PaO2 by > 47%. Correspondingly, PaCO2 increases of > 10% were observed in 35% of all sampling intervals, and [H+] increases of > 10% were observed in 24% of all sampling intervals. Because these blood gas changes were not reliably detected by using noninvasive monitoring and their magnitude is not predictable during OLV, intermittent BGA with short sampling intervals is warranted. In critical cases, continuous blood gas monitoring may be helpful. IMPLICATIONS: The magnitude of blood gas changes during thoracoscopic surgery with one-lung ventilation is not predictable and not reliably detected by noninvasive monitoring. Using a continuous intraarterial blood gas monitoring device, we demonstrated that intermittent laboratory blood gas analysis with short sampling intervals is warranted to detect arterial hypoxemia.

Adolescent↗
PubMed1999

Cerebral venous and tissue gases and arteriovenous shunting in the dog.

UNLABELLED: Cerebral venous blood gas values have been used to indicate brain tissue oxygenation. However, it is not clear how cerebral tissue and venous measures may vary under physiologic conditions caused by arteriovenous shunt. The purpose of this study was to measure brain tissue and local cerebral venous oxygen (PO2) and carbon dioxide (P(CO2)) partial pressure during changes in ventilation and to calculate shunt fraction. Eight dogs were anesthetized with isoflurane. After a craniotomy, a Neurotrend probe (Diametrics Inc., St. Paul, MN) that measures P(O2), P(CO2), pH, and temperature was inserted into brain tissue, and a small vein that drained the same tissue was catheterized. Arterial, cerebral venous, and brain tissue P(O2) and Pco2 were measured during random changes in ventilation to produce five different levels of inspired oxygen (room air, 40%, 60%, 80%, 95%) at each of three different end-tidal Pco2 (20 mm Hg, 40 mm Hg, 60 mm Hg). Arteriovenous shunt was calculated from oxygen and C(O2) content in artery, vein, and tissue, representing capillary. Tissue P(CO2) was 8 mm Hg greater than vein Pco2 during hypocapnia and this difference increased to 20 mm Hg during hypercapnia. Vein P(O2) was 8 mm Hg higher than tissue P(O2) during hypocapnia, and this difference increased to 40 mm Hg during hypercapnia. Shunt fraction increased from 10%-20% during hypocapnia to 50%-60% during hypercapnia. These results show that brain vein and tissue P(O2) and P(CO2) differ because of arteriovenous shunting and this difference is increased as end-tidal P(CO2) increases. IMPLICATIONS: We found, in dogs, that the gradient between brain venous and tissue P(O2) and PCO2 is increased with increased arterial P(CO2). The divergence between tissue and venous gases can be described by arterial to venous shunting.

Animals↗
PubMed1988

Changes in venous blood lactate, venous blood gases, and somatosensory evoked potentials after tourniquet application.

The effects of inflation of a 7-cm tourniquet applied to the upper arm of eight volunteers on venous lactate, venous blood gases, and ulnar nerve somatosensory evoked potentials (SSEPs) were investigated. The inflation pressure was 100 mmHg over the systolic pressure. Venous blood samples for lactate and blood gas determinations were withdrawn before tourniquet inflation; immediately and at 2, 5, 10, 15 min after tourniquet deflation; and additionally at 30, 45, and 60 min after deflation in the last four volunteers. SSEP stimulating surface electrodes were placed over the ulnar nerve at the wrist. Recording electrodes were placed over the ipsilateral ulnar groove of the elbow, Erb's point, and on the contralateral cortex. Averaged responses were acquired before inflation of the tourniquet, every 5-10 min during tourniquet inflation, and every 5-10 min for 45-60 min after tourniquet deflation. The tourniquet was inflated for 36 +/- 11 min. After deflation of the tourniquet, postdeflation pain and paresthesias were felt by five volunteers; these occurred at 30-120 s after deflation and lasted for 75-120 s. The postdeflation pains were characterized as burning, cramping, paresthesias, buzzing, or severe expansion of the hand. The venous blood lactate levels were significantly elevated for 10 min, and the time course of its change did not correlate with reperfusion pain. The PO2 and O2Hb saturation in venous blood were significantly elevated for 10-15 min after deflation. The elevated lactate and PO2 levels in the presence of a restored blood flow probably result from continued anaerobic muscle metabolism secondary to capillary closure from the tourniquet-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Monitoring of blood gases during prolonged experimental cardiopulmonary bypass and their relationship to brain pH, PO2, and PCO2.

Eight adult goats under went 5 hr of normothermic cardiopulmonary bypass (CPB) with pulsatile (n = 3) and nonpulsatile flow (n = 5). PaCO2 was maintained at 30-40 mmHg and blood flow rate at 50 ml/min/kg. Brain tissue pH, PO2, and PCO2, arterial and venous blood gases, and other systemic variables were monitored. No significant differences in brain electrochemistry between pulsatile and nonpulsatile perfusion were observed owing to the large variability of the results and the small number of experiments. The overall data for brain tissue pH, PO2, and PCO2 were analyzed and compared to the results of arterial and venous pH, PO2, and PCO2. Brain acidosis developed at the onset of bypass, and the values for brain tissue pH dissociated from those of blood pH, suggesting that hemodilution and the initial body response to CPB are involved in its development. Brain hypercapnia also developed during CPB, the values of brain tissue PCO2 dissociated from those of blood PCO2, and brain hypercapnia appears to be secondary to brain acidosis. Brain tissue PO2 closely followed the values of PvO2, suggesting that PvO2 can be an indicator of brain tissue PO2 during normothermic CPB and must be monitored during the procedure. Brain tissue acidosis is evidently related to neurologic dysfunction after CPB, and must be addressed. Replacement of the priming solution with whole blood or artificial blood, reduction of the priming volume, and application of vigorous pulsatile flow appear feasible interventions to mitigate brain tissue acidosis during CPB.

Acidosis↗
PubMed1993

Collecting and analyzing cord blood gases.

The analysis of cord blood respiratory gases and acid-base values is an important adjunct for determining the extent and cause of fetal acidosis at delivery. Although the quality and reliability of the blood gas instruments have improved dramatically, constant vigilance still is required and mandated to ensure accurate and precise results. Failure to control the many sampling and analysis variables that affect cord blood gas results will limit their usefulness. Most preanalytic problems become a minor concern when the blood gas analyses are done within a few minutes after obtaining the sample. Comparison of data among centers requires, not only that reference ranges be stated, but also that various corrections or factors that were used to adjust the results be described. Perhaps, a consensus could be reached to establish the optimal method of collection and the best methods for analyzing and reporting the results from cord blood gas and acid-base studies.

Adult↗
PubMed1982

Lung volume, dynamic lung compliance, and blood gases during the first 3 days of postnatal life in infants with meconium aspiration syndrome.

Serial measurements of pulmonary function and arterial blood gases during the first 3 postnatal days of life were obtained in 12 infants with meconium aspiration syndrome (MAS). Nine normal neonates with similar weight and gestational age were studied as controls. Infants with MAS has significantly lower pH on day 1, and had greater P(A-a)O2 throughout the study period than that of normal controls. The PCO2 was comparable between the groups. Both dynamic lung compliance (Cdyn) and specific lung compliance (C/VL) were lower in infants with MAS as compared with those of normal infants. The functional residual capacity (FRC) for normal infants on days 1, 2, and 3 were 2.0 +/- 0.3, 2.1 +/- 0.3, and 2.2 +/- 0.3 ml/cm, respectively, and for infants with MAS were 1.8 +/- 0.4, 2.3 +!- 1.1, and 2.2 +/- 0.6 ml/cm, respectively. Radiographic hyperinflation of the lungs was seen in 6 infants with MAS on day 1; 3 were associated with high FRC (greater than 2 SD of normal) and 2 with low FRC, indicating air trapping. The early use of PEEP should be cautious if hyperinflation or air trapping is present.

Blood Gas Analysis↗
PubMed1984

Transport of gases in high-frequency ventilation.

We found that the transport of gases in oscillating gas columns was proportional to oscillation frequency and the square of oscillation amplitude. When these results were applied to high-frequency oscillation and high-frequency jet ventilation in dogs, alveolar ventilation was proportional to frequency and to the square of tidal volume, and inversely proportional to anatomic dead space.

Animals↗
PubMed1987

Comparison of blood gases of ventilated patients during transport.

Three modes of ventilation during the transport of 30 ventilator-dependent patients were compared using blood gas variables. Ten were ventilated with a manually operated, ventilation bag (group C) and ten with a tidal volume meter at the exhalation valve of the ventilation bag (group V). Another ten patients (group O) were ventilated with a portable ventilator set to the minute volume (VE) given in ICU. VE was measured by volumetry as described above. Blood gases were analyzed in the ICU before and at the end of transport. In group C, significant decreases occurred in arterial (p less than .01) and central venous (p less than .05) PCO2, as well as in central venous PO2 (p less than .01). Arterial (p less than .05) and central venous (p less than .01) pH increased. Group V showed no statistically significant changes. In group O, arterial (p less than .01) and central venous (p less than .05) PCO2 decreased whereas arterial (p less than .01) and central venous (p less than .05) pH increased. We conclude that VE should be monitored during transport of ventilated patients.

Blood Gas Analysis↗
PubMed1988

Computer-controlled positive end-expiratory pressure titration for effective oxygenation without frequent blood gases.

We have previously designed a computerized system to automatically deliver PEEP to maintain functional residual capacity (FRC) at a desired value. The purpose of this study was to compare the computerized PEEP titration system with a standard clinical PEEP titration algorithm in the animal adult respiratory distress syndrome (ARDS) model. Thirty mongrel dogs were anesthetized, paralyzed, intubated, and ventilated. An acute pulmonary injury was produced using 0.09 ml/kg of oleic acid. The animals were then given PEEP for 5 h. Arterial and venous blood gases, BP, thermodilution cardiac output, heart rate, body temperature, total respiratory system compliance (Ctr), and end-tidal CO2 were measured every 30 min. FRC was measured using an automated sulfur hexafluoride washout system every 15 min. The animals were allocated randomly to three ten-animal groups. The first group had PEEP titrated using a standard clinical protocol; the remaining two groups had PEEP updated at 15-min intervals under computer control to maintain FRC at 1.4 times the postanesthetized, postparalyzed, preinjury value. The second group received fixed 3-cm H2O PEEP steps. The third group had variable size PEEP steps depending on the output of a proportional, integral, and derivative (PID) controller. PaCO2 was maintained at 35.8 +/- 3.4 (SD) torr. There was a significant difference in PEEP delivered between the three groups (p = .0006) and in FRC (p = .005). There was no significant difference in PaO2 (p = .80) or venous admixture (Qva/Qt) (p = .84) between the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Are arterial blood gases of value in treatment decisions for carbon monoxide poisoning?

Traditionally, the carboxyhemoglobin (HbCO) level has been used to estimate the severity of carbon monoxide (CO) poisoning. Through extensive clinical experience, we have found this to be an inaccurate correlation; thus, other variables such as pHa or psychometric abnormalities have been assessed to determine severity from CO poisoning. In a 5-yr experience with 247 patients, on admission 114 had an arterial blood gas and HbCO determinations, and 88 also had psychometric testing. The data were evaluated to determine any relationship between pH and HbCO level; a weak correlation (r approximately equal to -0.3) was discovered. A comparison of psychometric testing with HbCO level showed a much stronger statistical relationship. The definition of HbCO poisoning severity may be better determined by psychometric testing than by the HbCO level because psychometric testing measures actual neurologic disability. The weak correlation between both psychometric testing and the HbCO level with pHa reinforces the clinical impression that patients with acidosis, alkalosis, or normal blood gases could have equally severe neurologic symptomatology at HbCO levels ranging from 1% to 62%.

Blood Gas Analysis↗
PubMed2000

Effects of ventilation and nonventilation on pulmonary venous blood gases and markers of lung hypoxia in humans undergoing total cardiopulmonary bypass.

OBJECTIVE: To assess the effects of lung oxygenation and ventilation vs. lung collapse on pulmonary markers of lung hypoxia. DESIGN: A prospective, nonrandomized, nonblinded comparative study. SETTING: University department of anesthesiology and cardiothoracic surgery. SUBJECTS: Twelve adult patients undergoing coronary bypass grafting requiring total cardiopulmonary bypass. INTERVENTIONS: Single lung ventilation during total cardiopulmonary bypass (tidal volume, 150 mL; respiratory rate, 6 breaths/min; inspiratory oxygen fraction, 0.5) while the contralateral lung was allowed to collapse completely without oxygenation. MEASUREMENTS AND MAIN RESULTS: At the beginning and at the end of total cardiopulmonary bypass (duration, 59-65 mins), blood was aspirated from the right and left pulmonary veins and the radial artery for measurement of blood gases and concentrations of endothelin-1, big-endothelin, thromboxane B2, lactate, and lactate dehydrogenase. Nonventilation during total cardiopulmonary bypass compared with ventilation resulted in lower pulmonary venous P(O2) values (57+/-15 torr [7.6+/-2.0 kPa] vs. 103+/-23 torr [13.7+/-3.1 kPa]) and higher thromboxane B2 concentrations (488+/-95 pg/mL vs. 434+/-92 pg/mL). The concentrations of endothelin-1, big-endothelin, lactate, and lactate dehydrogenase in the pulmonary veins did not differ significantly between nonventilated and ventilated lungs. CONCLUSIONS: Development of pulmonary tissue hypoxia during 1 hr of nonventilation and cardiopulmonary bypass with completely inhibited pulmonary arterial blood flow is unlikely, suggesting that enough oxygen is stored in or is provided to the collapsed lung. Thus, nonventilation during total cardiopulmonary bypass does not appear to contribute to postoperative respiratory dysfunction by causing pulmonary tissue hypoxia. These results, however, do not exclude that mechanical factors of ventilation might benefit the lung during cardiopulmonary bypass.

Adult↗
PubMed1983

Radiation absorbed dose estimates for positron emission tomography (PET): inert gases 19Ne and 77Kr.

Detailed estimates of radiation absorbed dose based on solubility data and the distribution of body water and fat are presented for 19Ne and 77Kr, useful PET rCBF imaging agents. The steady-state inhalation of 75 mCi of 19Ne and the bolus inhalation of 18 mCi of 77Kr should result in comparable imaging statistics for typical protocols and lung radiation absorbed doses less than approx. 0.5 rad. A model for both steady-state and bolus inhalation techniques for soluble gases used for these radiation absorbed dose calculations is also presented.

Adipose Tissue↗