Dilution of alveolar gases during nitrous oxide excretion in man

1961 ◽  
Vol 16 (4) ◽  
pp. 723-728 ◽  
Author(s):  
Herbert Rackow ◽  
Ernest Salanitre ◽  
M. Jack Frumin
Keyword(s):  
Nitrous Oxide ◽  
Artificial Respiration ◽  
Different Types ◽  
Respiratory Mechanism ◽  
End Tidal ◽  
Theoretical Considerations

The effect of N2O excretion upon O2 and CO2 levels in man was studied during two different types of artificial respiration with air. When a constant inflating pressure type respirator was used, the average fall in end-tidal Pco2 was 2 mm Hg or 5%. The measured fall in alveolar Po2 could not be determined with confidence, although theoretical considerations indicate it to be greater than 5%. When the respirator was servo controlled by end-tidal CO2 in a manner closely analogous to the human central respiratory mechanism, with the Pco2 level thus held constant, the inflating pressure fell and the average arterial O2 saturation fell 2.8% (20 mm Hg, or a 21% fall). These results have been interpreted to reflect the influence of N2O excretion upon both alveolar O2 and CO2. Submitted on February 6, 1961

Residential Treatment of Disturbed Delinquents: Description of a Centre and Identification of Therapeutic Factors*

1987 ◽  
Vol 32 (7) ◽  
pp. 579-583 ◽  
Author(s):  
D.P. Harris ◽  
J.E. Cote ◽  
E.M. Vipond
Keyword(s):  
Residential Treatment ◽  
Clinical Work ◽  
Therapeutic Factors ◽  
Diagnostic Categories ◽  
Different Types ◽  
Using Data ◽  
Theoretical Considerations

Residential treatment for disturbed, particularly delinquent, adolescents has been described several decades ago by the founders and leaders of institutions. Theoretical considerations in treatment were prominent. The importance of structured milieu and the control of aggression came to acquire recognition. This study describes a structured centre, known to be effective in treating disturbed delinquents, using data gathered over twelve years of clinical work, observation and research. Factors considered essential in defining this institution are isolated and made compatible with the factors indicated by Rutter in his review of the residential treatment of delinquents. These factors are being used in a further study which compares the effectiveness of different types of facilities for a range of diagnostic categories.

scholarly journals A survey of the choice of general anaesthetic agents in Australia and New Zealand

2019 ◽  
Vol 47 (3) ◽  
pp. 235-241 ◽  
Author(s):  
Forbes McGain ◽  
Jason R Bishop ◽  
Laura M Elliot-Jones ◽  
David A Story ◽  
Georgina LL Imberger
Keyword(s):  
Nitrous Oxide ◽  
New Zealand ◽  
Gas Flow ◽  
General Anaesthetic ◽  
Gas Flows ◽  
Environmental Costs ◽  
Flow Rates ◽  
Intravenous Anaesthesia ◽  
Anaesthetic Agents ◽  
End Tidal

Strategies to reduce the adverse environmental costs of anaesthesia include choice of agent and fresh gas flows. The current preferences of Australian and New Zealand anaesthetists are unknown. We conducted a survey of Australian and New Zealand anaesthetists to determine the use of volatiles, nitrous oxide and intravenous anaesthesia, lowest fresh gas flow rates, automated end-tidal volatile control, and the rationales for these choices. The survey was answered by 359/1000 (36%), although not all questions and multiple responses within single questions were answered by all respondents. Sevoflurane was preferred by 246/342 (72%, 95% confidence interval (CI) 67%–77%), followed by propofol, 54/340 (16%, 95% CI 12%–20%), desflurane 39/339 (12%, 95% CI 8%–16%) and isoflurane 3/338(1%, 95% CI 0–3%). When asked about all anaesthetics, low-risk clinical profile was the most common reason given for using sevoflurane (129/301 (43%, 95% CI 37%–49%)), reduced postoperative nausea for propofol (297/318 (93%, 95% CI 90%–96%)) and faster induction/awakening times for desflurane (46/313 (79%, 95% CI 74%–83%)). Two-thirds (226/340 (66%, 95% CI 61%–71%)) of respondents used nitrous oxide in 0–20% of general anaesthetics. Low fresh gas flow rates for sevoflurane were used by 310/333 (93%, 95% CI 90%–95%) and for 262/268 (98%, 95% CI 95%–99%) for desflurane. Automated end-tidal control was used by 196/333 (59%, 95% CI 53%–64%). The majority of respondents (>70%) preferred sevoflurane at low flows. These data allow anaesthetists to consider further whether changes are required to the choices of anaesthetic agents for environmental, financial, or any other reasons.

Nitrous oxide emissions from an Andosol upland field amended with four different types of biochars

2019 ◽  
Vol 113 (3) ◽  
pp. 323-335
Author(s):  
Akinori Yamamoto ◽  
Hiroko Akiyama ◽  
Masahiro Kojima ◽  
Ayano Osaki
Keyword(s):  
Nitrous Oxide ◽  
Nitrous Oxide Emissions ◽  
Different Types ◽  
Upland Field

Fentanyl Augments the Blockade of the Sympathetic Response to Incision (MAC-BAR) Produced by Desflurane and Isoflurane 

1998 ◽  
Vol 88 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Malcolm Daniel ◽  
Richard B. Weiskopf ◽  
Mariam Noorani ◽  
Edmond I. Eger
Keyword(s):  
Nitrous Oxide ◽  
Cardiovascular Response ◽  
Dependent Manner ◽  
Surgical Incision ◽  
Arterial Blood ◽  
Adrenergic Response ◽  
The Mean ◽  
End Tidal ◽  
Inhaled Anesthetic ◽  
Dose Dependent

Background Heart rate (HR) or mean arterial blood pressure (MAP) may increase in response to incision despite the absence of a motor response. The authors hypothesized that the MAC-BAR (minimum alveolar concentration of an anesthetic that blocks adrenergic response to incision) for isoflurane would exceed that for desflurane, and that fentanyl would decrease the MAC-BAR for each anesthetic in a dose-dependent manner. Methods Seventy-one patients were randomly allocated to one of six groups: desflurane or isoflurane without fentanyl or with 1.5 or 3 microg/kg fentanyl given intravenously 5 min before surgical incision. Anesthesia was induced with 2 mg/kg propofol given intravenously, and tracheal intubation facilitated with 0.1 mg/kg given intravenously. The first patient in each group received 1 MAC (end-tidal) of the inhaled anesthetic in 60% nitrous oxide (0.55 MAC), balance oxygen, maintained for at least 10 min before incision. The response was considered positive if the HR or MAP increased 15% or more. If the response was positive, the end-tidal concentration given to the next patient was 0.3 MAC greater; if the response was negative, the end-tidal concentration was 0.3 MAC less. The MAC-BAR level was calculated as the mean of four independent cross-over responses in each group. Results Desflurane and isoflurane anesthesia with 60% nitrous oxide did not change HR (P > 0.05) and decreased MAP (P < 0.05) before incision. Plasma epinephrine and norepinephrine concentrations after anesthesia and before incision were normal in all groups. The MAC-BAR level, without fentanyl, did not differ (P > 0.05) between desflurane (1.30 +/- 0.34 MAC [mean +/- SD]) and isoflurane (1.30 +/- 0.18 MAC). Fentanyl given at 1.5 microg/kg intravenously equivalently (P > 0.05) reduced the MAC-BAR for desflurane (to 0.40 +/- 0.18 MAC; P < 0.05) and isoflurane (to 0.55 +/- 0.00 MAC; P < 0.05), but a further increase in fentanyl to 3 microg/kg caused no greater decrease in the MAC-BAR for desflurane (0.48 +/- 0.16 MAC) and isoflurane (0.40 +/- 0.30 MAC). Conclusions Clinically attainable doses of desflurane and isoflurane, in 60% nitrous oxide (0.55 MAC), block the cardiovascular response to surgical incision at 1.3 MAC. Fentanyl given at 1.5 microg/kg decreases the MAC-BAR for each agent with no further decrease produced by 3 microg/kg fentanyl.

The Effect of Specimen Thickness on Rate of Artificial Aging

1932 ◽  
Vol 5 (4) ◽  
pp. 698-704
Keyword(s):  
Accelerated Aging ◽  
Mass Action ◽  
Specimen Thickness ◽  
Oxygen Bomb ◽  
Aging Period ◽  
Bomb Test ◽  
Different Types ◽  
Satisfactory Answer ◽  
Theoretical Considerations

Abstract From time to time the question of the effect of thickness on the rate of deterioration of rubber samples subjected to accelerated aging tests, particularly the oxygen-bomb test, is raised. Apparently little experimental work has been done, and no satisfactory answer has yet been given. According to the well-known laws of mass action, the rate of deterioration should slow up with increasing thickness of rubber, and one might expect thin articles to deteriorate further, in a given bomb-aging period, than similar articles of heavier gage. Nevertheless, it is tacitly assumed that variations in thickness have practically no effect—and for small variations this assumption is reasonable considering the oxygen concentration used; or possibly no assumption is made, and the aging tests are just performed mechanically without regard for theoretical considerations and possibilities. The fact that the oxygen-bomb is used largely for comparing the aging quality of similar articles, usually of comparable gage, has doubtless tended to keep the question of the influence of thickness dormant. Again, in the testing of laboratory compounds, most laboratories have standardized on a uniform thickness of cured slabs (0.075″), so that the question of thickness in this type of work does not come into the picture. Occasionally, however, it may be desirable to compare the bomb-aging behavior of articles of quite different types, and when in such cases there is a large difference in thickness, the validity of the comparison may be called in question.

HALOTHANE AND NITROUS OXIDE IN END-TIDAL AIR AND VENOUS BLOOD OF SURGICAL PERSONNEL

1973 ◽  
Vol 17 (5) ◽  
pp. 465???466
Author(s):  
P. PF??FFLI ◽  
P. NIKKI ◽  
K. AHLMAN
Keyword(s):  
Nitrous Oxide ◽  
Venous Blood ◽  
End Tidal

Xenon Provides Faster Emergence from Anesthesia than Does Nitrous Oxide-sevoflurane or Nitrous Oxide-isoflurane 

1997 ◽  
Vol 86 (6) ◽  
pp. 1273-1278 ◽  
Author(s):  
Takahisa Goto ◽  
Hayato Saito ◽  
Masahiro Shinkai ◽  
Yoshinori Nakata ◽  
Fumito Ichinose ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Minimum Alveolar Concentration ◽  
Total Abdominal Hysterectomy ◽  
Abdominal Hysterectomy ◽  
Patient Demographics ◽  
The Mean ◽  
American Society ◽  
End Tidal ◽  
To Receive ◽  
Rapid Emergence

Background Xenon, an inert gas with anesthetic properties (minimum alveolar concentration [MAC] = 71%), has an extremely low blood:gas partition coefficient (0.14). Therefore, we predicted that xenon would provide more rapid emergence from anesthesia than does N2O+isoflurane or N2O+sevoflurane of equivalent MAC. Methods Thirty American Society of Anesthsiologists class I or II patients undergoing total abdominal hysterectomy were randomly assigned to receive 60% xenon, 60% N2O + 0.5% isoflurane, or 60% N2O + 0.70% sevoflurane (all concentrations are end-tidal: n = 10 per group). After placement of an epidural catheter, anesthesia was induced with standardized doses of midazolam, thiopental, and fentanyl. Thirty minutes later, xenon, N2O+isoflurane, or N2O+sevoflurane was started as previously assigned. These regimens were supplemented with epidural anesthesia with mepivacaine so that the mean arterial pressure and heart rate were controlled within 20% of the preoperative values. At the end of operation lasting approximately 2 h, all inhalational anesthetics were discontinued, and the patients were allowed to awaken while breathing spontaneously on an 8 l/min inflow of oxygen. A blinded investigator recorded the time until the patient opened her eyes on command (T1), was judged ready for extubation (T2), could correctly state her name, her date of birth, and the name of the hospital (T3), and could count backward from 10 to 1 in less than 15 s (T4). Results Emergence times from xenon anesthesia were: T1, 3.4 +/- 0.9 min; T2, 3.6 +/- 1 min; T3, 5.2 +/- 1.4 min; and T4, 6.0 +/- 1.6 min (mean +/- SD). These were one half to one third of those from N2O+sevoflurane (T1, 6.0 +/- 1.7 min; T4, 10.5 +/- 2.5 min) or N2O+isoflurane (T1, 7.0 +/- 1.9 min; T4, 14.3 +/- 2.8 min) anesthesia. The three groups did not differ in terms of patient demographics, the duration of anesthesia, the amount of epidural mepivacaine administered, or the postoperative pain rating. No patient could recalls intraoperative events. Conclusions Emergence from xenon anesthesia is two or three times faster than that from equal-MAC N2O+isoflurane or N2O+sevoflurane anesthesia.

Effects of Two Target-controlled Concentrations (1 and 3 ng/ml) of Remifentanil on MACBARof Sevoflurane

2004 ◽  
Vol 100 (2) ◽  
pp. 255-259 ◽  
Author(s):  
Andrea Albertin ◽  
Andrea Casati ◽  
Piercarlo Bergonzi ◽  
Greta Fano ◽  
Giorgio Torri
Keyword(s):  
Nitrous Oxide ◽  
Skin Incision ◽  
Double Blind Study ◽  
Double Blind ◽  
Surgical Incision ◽  
Arterial Blood ◽  
Sequential Allocation ◽  
Sympathetic Responses ◽  
American Society ◽  
End Tidal

Background The aim of this prospective, randomized, double-blind study was to determine the effects of two different target-controlled concentrations of remifentanil (1 and 3 ng/ml) on the sevoflurane requirement for blunting sympathetic responses after surgical incision (MACBAR). Methods Seventy-four patients aged 20-50 yr, with American Society of Anesthesiologists physical status I, were anesthetized with propofol, cisatracurium, and sevoflurane with a mixture of 60% nitrous oxide in oxygen. Then, patients were randomly allocated to receive no remifentanil infusion (n = 27) or a target-controlled plasma concentration of 1 ng/ml (n = 27) or 3 ng/ml remifentanil (n = 20). Sympathetic responses to surgical incision (presence or absence of an increase in either heart rate or mean arterial blood pressure of 15% or more above the mean of the values measured during the 2 min before skin incision) were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and the MACBAR for each group were determined using an up-and-down sequential-allocation technique. Results The MACBAR of sevoflurane was higher in the group receiving no remifentanil (2.8% [95% confidence interval: 2.5-3.0%]) as compared with patients of the groups receiving 1 ng/ml (1.1% [0.9-1.3%]; P = 0.012) and 3 ng/ml remifentanil (0.2% [0.1-0.3%]; P = 0.006). When considering a minimum anesthetic concentration (MAC) value in this age population and the contribution of 60% nitrous oxide (0.55 MAC), the combined MACBAR values, expressed as multiples of the MAC, were 1.95 MAC, 1.1 MAC, and 0.68 MAC, in the three groups, respectively. Conclusion A target-controlled concentration of 1 ng/ml remifentanil results in a 60% decrease in the MACBAR of sevoflurane combined with 60% nitrous oxide. Increasing the target concentration of remifentanil to 3 ng/ml produces a further 30% decrease in the MACBAR values of sevoflurane.

scholarly journals The system paradigm revisited

2016 ◽  
Vol 66 (4) ◽  
pp. 547-596 ◽  
Author(s):  
János Kornai
Keyword(s):  
Thomas Kuhn ◽  
Third Wave ◽  
Capitalist System ◽  
Specific Approach ◽  
Politics And Government ◽  
The Third ◽  
Different Types ◽  
Governmental Form ◽  
Theoretical Considerations ◽  
System Paradigm

The term paradigm was introduced to the philosophy of science by Thomas Kuhn — he used this term to denote the specific approach applied by a school of reasearch to examine its subject matter. Researchers using the same paradigm seek answers to similar questions, and employ similar methods and concepts. In an article published in 2000, the author of this essay introduced the term system paradigm, which focuses on the systems functioning in a society. This study develops the theoretical considerations outlined in that earlier article on the basis of experience on post-socialist transition. The first part compares the socialist and capitalist systems, describing their main characteristics, and concludes that the capitalist system has become established in former socialist countries, except for North Korea and Cuba. The second part analyzes varieties of capitalism within a typology which classifies prevailing forms of politics and government. Three markedly different types are identified: democracy, autocracy, and dictatorship. Huntington wrote about the “third wave” of democratization. This study concludes the third wave has dried up: for the 47 post-socialist countries, only a tenth of the population live in democracy, while autocracy or dictatorship prevails in all other countries in this group. The third part of this essay applies the conceptual and analytical apparatus to Hungary, where capitalism exists, and autocracy is the prevailing politico-governmental form — here we can find important characteristics common to other capitalist countries or other autocracies. This finding is compatible with the observation that there are some, less fundamental, characteristics unique to Hungary, or “Hungarica”, which differ from the characteristics of all other countries.1

scholarly journals Effects of nitrous oxide on minimum alveolar concentration of desflurane in dogs

2007 ◽  
Vol 59 (1) ◽  
pp. 97-104 ◽  
Author(s):  
C.T. Nishimori ◽  
N. Nunes ◽  
D.P. Paula ◽  
M.L. Rezende ◽  
A.P. Souza ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Body Temperature ◽  
Minimum Alveolar Concentration ◽  
Electric Stimulus ◽  
Oxyhemoglobin Saturation ◽  
End Tidal Carbon Dioxide ◽  
Desflurane Concentration ◽  
Blood Pressures ◽  
End Tidal

Effects of nitrous oxide (N2O) on minimum alveolar concentration (MAC) of desflurane were studied. For that purpose, 30 dogs were randomly allocated into two groups: desflurane group (GD) and N2O and desflurane group (GDN). GD animals received propofol to intubation, and 11.5V% of desflurane diluted in 100% O2. After 30 minutes, they received electric stimulus and if the animal did not react to stimulus, desflurane concentration was reduced by 1.5V%. This protocol was repeated at each 15 minutes, and stimulus was interrupted when voluntary reaction was observed. GDN dogs were submitted to diluent flow 30% O2 and 70% N2O. Desflurane's MAC; heart (HR) and respiratory (RR) rates; systolic, diastolic and mean arterial pressures (SAP, DAP, and MAP, respectively); end tidal carbon dioxide (ETCO2); oxyhemoglobin saturation (SpO2) and body temperature (T) were evaluated. In both groups increase in HR and ETCO2, and decrease in RR and T were associated with administration of the highest dose of desflurane. Blood pressures decreased 30 minutes after desflurane administration in GDN, and after this measurement the values increased. Reduction in desflurane's MAC was observed as well. It is concluded that N2O associated with desflurane reduced desflurane's MAC by 16% with increase in HR and respiratory depression.

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