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PubMedDate not supplied

Comparison of driving gases for IABPs.

Several aspects of CO2 vs He as the driving gas in intra-aortic balloon counterpulsation systems were reviewed and investigated. Carbon dioxide seems to be significantly safer than other gases, but not benign. Helium produces a faster balloon response, but the physiologic significance has not been defined. Balloon driving gases become diluted in relatively short time. Leak detection systems have significant limitations. It seems prudent for users of dual-balloon systems to periodically measure the PCO2 of the driving gas. A better method of purging the single-balloon system was developed.

Animals↗
PubMed1981

Sequential changes in placental blood gases and pH during the hour following delivery.

We studied the effect of a delay in blood sampling on the measurement of placental blood gases, pH and calculated bicarbonate. Blood was sampled serially at 15-minute intervals during the hour following delivery from placentas and attached umbilical cords of unasphyxiated term neonates. Placentas and attached cords were stored at room temperature. When blood was sampled exclusively from the segment of the umbilical vein lying within the umbilical cord, there were no statistically significant changes during the time of study in pH, PCO2 or PoO2. When some or all of the serial samples were taken from vessels on the surface of the placenta, there was a statistically and biologically significant decrease in the pH and increase in the PCO2 values of the blood. Our results indicate that the validity of the measurements of umbilical venous blood gases and pH is not affected by up to an hour's delay in blood sampling.

Bicarbonates↗
PubMed1982

A central low vacuum pipeline system for the disposal of waste anaesthetic gases.

An independent low vacuum pipeline system for scavenging waste anaesthetic gases is described. The pipeline system has terminal points in several operating and induction rooms. At each terminal point a connection box is installed, eigher in the wall or in a ceiling pendant. Excess gases from the anaesthetic apparatus or the patient ventilator are collected in a reservoir and subsequently sucked through the pipeline system, together with a surplus of air, extracted from the room via openings in the terminal box. The total suction rate is 100 1/min at each terminal box. Once connected, the system needs no looking after by the anaesthetist. Sub-atmospheric and positive pressures, measured at the point of connection to the anaesthetic apparatus are always between -11 Pa and +60 Pa, complying with the current standards.

Anesthesiology↗
PubMed1980

A mask for delivery of inhalation gases to small laboratory animals.

A mask was developed for the administration of volatile anesthetics and other gases to small, spontaneously breathing laboratory animals. A vacuum-powered venting system surrounding the inspiratory gas supply prevented potentially hazardous gases from escaping into the environment. This system was used to deliver nitrous oxide, halothane, and methoxyflurane to rats, gerbils, and newborn dogs. It was used to vary the oxygen and carbon dioxide concentrations inspired by spontaneously breathing animals undergoing physiological experiments.

Anesthesia, Inhalation↗
PubMed1980

Reduction of operative heat loss and pulmonary secretions in neonates by use of heated and humidified anesthetic gases.

Maintaining normothermia in neonates undergoing major operations remains a serious problem which may complicate the perioperative period. During the past 5 years at the UCLA Hospital, 86 infants have undergone general anesthesia for repair of congenital malformations. Heated, humidified ventilation (HHV) was used in 48 neonates and standard ventilation (SV)--that is, dry anesthetic gases--was used in the other 38. We found that loss of body heat during the period of anesthesia was significantly less when HHV was used. The mean rectal temperature of HHV infants decreased 0.2 degrees C during the first hour of anesthesia, whereas the mean temperature decreased 1.4 degrees C in SV infants (p < 0.01). By the end of anesthesia, the mean temperature of HHV infants had increased 0.3 degrees C, whereas in SV infants the mean temperature was 1.2 degrees C lower than at the beginning of anesthesia (p < 0.01). Furthermore, postoperative atelectasis was less frequent in HHV patients (three cases) than in SV infants (nine cases), and pulmonary secretions were less voluminous and tenacious in neonates receiving heated humidified anesthetic gases, although objective quantification of these observations was not done. Inasmuch as no complications were observed in any of the 48 neonates receiving HHV, and previous studies showed that HHV does not interfere with anesthetic gas uptake, it appears that HHV may be a useful adjunct to the currently used methods of neonatal anesthesia.

Abdomen↗
PubMed1995

[Exposure to anesthetic gases].

In recent years there has been a growing awareness of possible hazards caused by anaesthetic gases in operating theatres. Our study monitored ambient nitrous oxide (N2O) levels in the operating theatres and recovery rooms at the University Hospital in Tromsø. The results show that exposure to waste anaesthetic gases occurs because of leaks in the anaesthetic equipment. The three major sources of leaks are masks, high pressure fittings and exhalation valves. Prevention of leakage from equipment is very important, and a leakage testing programme should be an essential part of the daily control strategy. Good working practices and tracheal intubation results in low exposure to nitrous oxide in the breathing zone of the anesthetic personnel. During mask anaesthesia we have observed nitrous oxide concentrations above 1500 ppm, owing to mask leakage. A closely fitting scavenging mask and good working practices lead to in lower nitrous oxide concentrations. Nitrous oxide exhalation from the patient in the recovery room is only a minor problem.

Air Pollutants, Occupational↗
PubMed1994

Preservation of humidity and heat of respiratory gases in patients with a minute ventilation greater than 10 L/min.

OBJECTIVE: To compare the temperature and humidification output of one heated humidifier system (Bennett Cascade 2 Humidifier) and two heat and moisture exchangers (Pall Ultipor, BB 50, and Humid-Vent Filter) in intensive care unit (ICU) patients submitted to a minute ventilation of > 10 L/min. DESIGN: Prospective, controlled, randomized, unblinded study. SETTING: ICU of a university hospital. PATIENTS: Eleven sedated and paralyzed patients who required controlled mechanical ventilation with a minute ventilation of > 10 L/min for > 3 days. INTERVENTIONS: After a randomized selection process, the patients were ventilated for 24-hr periods with the humidifier and one of the heat and moisture exchangers. Both heat and moisture exchangers were first tested for 45 mins; then, the heat and moisture exchanger that demonstrated the best performance in terms of temperature and water preservation was tested for 24 hrs. MEASUREMENTS AND MAIN RESULTS: During the inspiration phase for each patient, the following measurements were performed: mean and minimum values of temperature, relative and absolute humidity of inspired gases. During the 45-min test period, the Humid-Vent Filter had a better temperature and humidification output than the Pall Ultipor Filter and thus was tested for 24 hrs. The Bennett Cascade 2 Humidifier and the Humid-Vent Filter had a better thermic capacity than the Pall Ultipor Filter (p < .001). No difference was ever observed between the Bennett Cascade 2 Humidifier and the Humid-Vent Filter regarding relative humidity. The Pall Ultipor Filter had a lower temperature and humidification output when compared with the other two systems (p < .007). Concerning absolute humidity of inspired gases, the Pall Ultipor Filter achieved a lower performance than any other tested systems (p < .02). A small but significant decrease in temperature and absolute humidity, but not in relative humidity, was seen after 24 hrs of use with the Humid-Vent Filter. However, with this heat and moisture exchanger, all patients had an absolute humidity of > 28 mg H2O/L and a relative humidity of > 93% after 24 hrs of use. CONCLUSIONS: In patients with a minute ventilation of > 10 L/min (> 10.5 to 16.0 L/min), the Humid-Vent Filter had a temperature and humidification output close to the reference system (the Bennett Cascade 2 Humidifier). The Pall Ultipor Filter had a significantly lower temperature and humidification output in these patients.

Acute Disease↗
PubMed1994

[Pollution of operating room air by anesthetic gases in relation to the air conditioning method and anesthesia techniques].

Volatile anesthetics are suspected to cause various health risks even in subnarcotic concentrations (hepatotoxicity, mutagenicity, teratogenicity). Yet only for halothane a limit (MAK-value = 5 ppm) has been established for the entire FRG. In addition, in 1991 Hamburg and Schleswig-Holstein defined preliminary limits for isoflurane, enflurane and nitrous oxide. We analysed the pollution of operating-room air by narcotic gases in 20 hospitals of Niedersachsen. In several cases limits have been exceeded evidently. Reasons for high concentrations were: insufficient room ventilation, defective air-conditioning plants, technical defects (leakage) and high gas emission due to special techniques in anesthesia (bronchoscopy). In order to take care of personnel-health air concentration of anesthetic gases should be kept as low as possible by the help of sufficient room ventilation avoiding unnecessary emissions.

Air Conditioning↗
PubMed1994

[Effects of diltiazem hydrochloride on blood gases].

The effects of diltiazem, Ca ion channel blocker, on arterial blood gases were evaluated in 50 patients (G-I: 24 patients undergoing abdominal surgery, G-II: 26 patients undergoing non-abdominal surgery). Diltiazem hydrochloride was administered to prevent intraoperative hypertension as a bolus (5 mg) followed by a continuous infusion (5-10 micrograms.kg-1.min-1). Arterial blood gases were analyzed just before, as well as 5 and 15 min after the administration of diltiazem. In G-I, arterial blood oxygen tension decreased significantly (P < 0.001) from 210.8 +/- 42.4 to 197.7 +/- 50.2 mmHg 5 min after infusion, and to 193.2 +/- 53.4 mmHg 15 min after; while there was no significant difference in G-II. Diltiazem infusion may deteriorate oxygenation in patients undergoing abdominal surgery, and therefore oxygenation should be carefully monitored.

Abdomen↗
PubMed1976

[Simulation of polluted atmospheres for animal experimentation: toxic gases].

A process for the generation of standardized polluted atmospheres usable for animal exposure is described. It is based on the diffusion of compressed gases across a silicone membrane. This device has been tested with four gases of particular importance in the field of atmospheric pollution (sulfur dioxide, nitrogen oxide, carbon monoxide and ammoniac).

Air Pollutants↗
PubMed1996

[Study of arterial blood gases in liver cirrhosis with and without ascites].

OBJECTIVE: The study of the disturbances of arterial gases and the changes in the arterial pH which are present in patients with liver cirrhosis and ascites and their modification after the disappearance of ascites by treatment. EXPERIMENTAL DESIGN: Open study,with protocol and prospective, to evaluate the changes in measurement of the arterial gases and acid-base, parameters in matching groups of patients. PATIENTS: We include 24 patients, 15 males and 9 females, without preliminary or cardio-respiratory pathology age range between 37 and 77 years, average of 56.8 years, all of them diagnosed of liver cirrhosis of different etiologies and with important ascites. All of them finished the study. RESULTS: In patients with liver cirrhosis and ascites a fall in the PaO2 and in the PaCO2 was demonstrated the pH in the upper limit of the normality compatible with hypoxemia and respiratory alkalosis. After the disappearance of the ascites, a significant improvement in the PaO2 (p < 0.05), without any changes in the PaCO2 and pH values was apparent. CONCLUSIONS: In patients with liver cirrhosis, with or without ascites, hyperventilation is present, that can be multifactorial in origin, but which really has an unknown cause. We have found no relationship with the circulating levels of progesterone.

Acid-Base Equilibrium↗
PubMed1996

Breathing a mixture of inert gases: disproportionate diffusion into decompression bubbles.

To study the consequences of diving with gas mixtures, we simulated growth of decompression bubbles using an equation system that accounts for major determinants of bubble behavior. When breathing a mixture, bubbles are smaller than expected from linear interpolation between bubbles with either of the unmixed component gases because of disproportionate diffusion effects: a) When few bubbles form, the inert gas that permeates fastest becomes over-represented, relative to the breathing gas, inside bubbles during growth; this slows further entrance of the fast gas and enhances entrance of the slower gas. b) With N2-He mixtures and few bubbles, the over-represented gas is He in aqueous tissue, but is N2 in lipid tissue. c) When many bubbles form, the over-represented gas is the one with higher tissue solubility. Our simulations indicate that the smallest bubbles always occur with breathing of one of the component gases, but which gas that is depends on whether the tissue is lipid or aqueous and whether few or many bubbles form.

Absorption↗
PubMed1996

Effect of lateral position on arterial and venous blood gases in postoperative cardiac surgery patients.

BACKGROUND: Investigators have suggested that lateral position may have clinically significant effects on oxygenation in cardiac surgery patients. Presence of lung disease and type of cardiac surgery may be important considerations. OBJECTIVES: To determine the effect of position (left, right, supine) on blood gases in patients who have had coronary artery bypass or cardiac valvular surgery and to compare the effect of position on blood gases in cardiac surgery patients having preoperatively diagnosed lung disease with those having no lung disease. METHODS: A repeated measures design was used to study 120 mechanically ventilated, postoperative cardiac surgery patients. Subjects were randomly assigned a sequence of three positions (supine, and 45; right and left lateral) after cardiac surgery. Heart rate, respiratory rate, and arterial blood gas values were collected in each position. Venous blood gas values were collected from a subset of 40 subjects. RESULTS: A statistically significant effect of position on PaO2 was found in the group as a whole. The mean PaO2 in the left lateral position was lower than the value in the right or supine positions. No significant effects for position and pH, PaCO2, or bicarbonate were detected. No significant effects were found for type of surgery or the presence of absence of preoperative lung disease. A significant effect of position on venous pH was detected. No significant position effects were found for PvO2, PvCO2, bicarbonate, or venous saturation. No significant position effects were found for the calculated arterial-venous oxygen difference. CONCLUSIONS: The results of this study support those of previous research, which reported lower PaO2 in postoperative coronary artery bypass graft patients in the left lateral position. Mean differences in PaO2 were small, suggesting that the known benefits of lateral positioning in the early postoperative period outweigh the potential risks.

Adult↗
PubMed1996

[Evaluation of vaporizers by anesthetic gas monitors corrected with a new method for preparation of calibration gases].

For resolving the discrepancy of concentrations found among anesthetic gas monitors, the author proposed a new method using a vaporizer as a standard anesthetic gas generator for calibration. In this method, the carrier gas volume is measured by a mass flow meter (SEF-510 + FI-101) installed before the inlet of the vaporizer. The vaporized weight of volatile anesthetic agent is simultaneously measured by an electronic force balance (E12000S), on which the vaporizer is placed directly. The molar percent of the anesthetic is calculated using these data and is transformed into the volume percent. These gases discharging from the vaporizer are utilized for calibrating anesthetic gas monitors. These monitors are normalized by the linear equation describing the relationship between concentrations of calibration gases and readings of the anesthetic gas monitors. By using normalized monitors, flow rate-concentration performance curves of several anesthetic vaporizers were obtained. The author concludes that this method can serve as a standard in evaluating anesthetic vaporizers.

Anesthetics, Inhalation↗
PubMed1997

[A study of waste anesthetic gases monitoring and working environmental controls in hospital operating rooms].

There are hazardous factors threatening health care workers, and many hazardous chemical substances have been reported in operating rooms, central supply facilities, laboratories and so on. In Japan, little attention has been paid to exposure to these chemicals and to working environmental controls. Waste anesthetic gases are chemicals concerned, and we conducted environmental monitoring continuously and measured exposure to nitrous oxide, isoflurane and sevoflurane in operating rooms, and examined working environmental controls. The average environmental concentrations of nitrous oxide were about 400 ppm in anesthetists' working areas, and about 180 ppm in surgeons' and instrument nurses' working areas under unscavenged conditions. Under scavenged conditions, environmental concentrations were 70-190 ppm in anesthetists' zones, and 70-90 ppm in surgeons' and instrument nurses' zones. Even under scavenged conditions, operating room personnel are presumed to be exposed to high concentrations of nitrous oxide above ACGIH's TLV and NIOSH's REL. The level of exposure of isoflurane and sevoflurane was 2-4 ppm. Managing general ventilation system and airflow direction, working area under scavenged system, environmental concentration levels of nitrous oxide could be reduced to 20-30 ppm. In order to control occupational exposure to anesthetic gases, it is not sufficient to merely adapt scavenging systems in operating rooms. Working environmental control and occupational hygiene management should be required.

Air Pollutants, Occupational↗
PubMedDate not supplied

[Hepatologic parameters in health personnel after several years of occupational exposure to anesthetic gases].

The aim of this study was to indicate necessity of establishing sensitive methods for early detection of hepatobiliary tract disorders after exposure of medical staff to anesthetic gases, as well as to follow-up working conditions in operating rooms. The examined group comprised the medical staff of the Surgical Department of the Institute of Surgery in Novi Sad. In the group of examinees levels of bilirubin in blood were increased; prevalent increase of the indirect bilirubin occurred too, while she increase of the direct bilirubin concentration was almost insignificant. Alanine aminotransferase concentration was slightly increased in the examined group, while aspartate aminotransferase reacted in much more expressed concentration increase. On the basis of gathered results it can be concluded that there are, for now, slight functional hepatic changes in the exposed workers, which may be the consequence of exposure to anesthetic gases.

Adult↗
PubMedDate not supplied

Measurement and interpretation of arterial blood gases.

Arterial blood gases and pH are routinely being measured in clinical practice, both to provide diagnosis and to guide therapy in critically ill patients. Oximetry is clinically useful in establishing the presence of hypoxaemia in patients with respiratory diseases. Oximetry is also a simple and reliable method for monitoring patients undergoing anaesthesia, sleep studies and cardiopulmonary exercise testing. The search continues for new innovative techniques for continuous transcutaneous and intra-arterial blood gas monitoring. This is essential in the management of critically ill patients because blood analysers provide only intermittent monitoring of arterial blood gases.

Blood Gas Analysis↗
PubMed1997

Interpretation of neonatal blood gases, Part I: Physiology and acid-base homeostasis.

Accurate interpretation of blood gases is paramount in clinical management in the NICU. This interpretation should be based on a sound understanding of acid-base physiology. Acid-base homeostasis depends on a series of complex chemical reactions controlled by the kidneys and the lungs. The maintenance of a blood pH within the narrow range required for normal cellular reactions requires a balance between acid production and excretion. Somewhat separate but equally important to blood gas interpretation is an understanding of oxygen transport. Included in this is the relationship between oxygen and hemoglobin. This article, the first in a two-part series, discusses the physiology of acid-base balance and oxygen transportation. The second article provides an approach for systematic interpretation of blood gases.

Acid-Base Equilibrium↗