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1.
The resistance to gas flow is measured in the Jackson-Rees modification of the Ayre's T-piece, the "Bain" circuit, and the circle circuit using the conventionally employed rubber tubing, or either of two coaxial circle tubing systems. The Ayre's T-piece has the lowest resistance to gas flow, followed by the circle circuit with conventional rubber tubing, then the "Bain" circuit and the coaxial circle circuits. When the resistance to gas flow in the inspiratory limb is measured with a tracheal tube attached to each circuit the resistances increase in magnitude, but the differences among the circuits become less significant.  相似文献   

2.
During closed-circuit anesthesia, the patient's inspired gas may become progressively contaminated by nonanesthetic gases. We studied the concentrations of methane, acetone, and nitrogen as nonanesthetic gas contaminants in the circuit gas of 16 cases during closed-circuit anesthesia. After a "short" period of denitrogenation (6-8 min), average nitrogen concentration in the closed circuit increased from 6.4 to 16.2%, methane from 4.3 to 22.4 ppm, and acetone from 0.3 to 2.2 ppm. After "long" denitrogenation (33 min), average nitrogen concentration in the closed circuit increased from 1.0 to 5.1%, methane from 3.7 to 17.9 ppm, and acetone from 1.3 to 5.9 ppm. It is concluded that gases stored in tissues or produced within the body can appear in the patient's expired gas during closed-circuit anesthesia. Intermittent flushing of the circuit with high flow gases is suggested to remove these contaminants.  相似文献   

3.
It is demonstrated that special surface of extracorporeal circuit promotes reduction of artificial circulation negative influence on hemostasis system. During artificial circulation coating "duraflo" gradually loses its protective characteristics due to washout of heparin molecules from the surface of extracorporeal circuit, whereas chemical link between heparin and protein in "safe-line" coating is more stable. The results of the study demonstrate no advantages of heparin coating of extracorporeal circuits over protein one. Finally, all the advantages of extracorporeal circuits with "safe-line" coating lead to a decrease of postoperative blood loss.  相似文献   

4.
A method of converting a Mapleson D (Bain) circuit to closed-circuit operation is presented, utilizing a laboratory air pump and a Waters carbon dioxide absorber canister to recirculate exhaled gas. The elimination of carbon dioxide from the circuit was studied and found to be adequate. The circuit would allow the use of low fresh gas flows for the maintenance of anaesthesia without the danger of carbon dioxide rebreathing. We suggest that such a circuit could provide appropriate conditions of gas humidity and temperature for endotracheal anaesthesia, while realizing the advantage of a circulator in mask anaesthesia is possible. Further design considerations for a "D circle" breathing system for clinical use are discussed.  相似文献   

5.
Interval and circuit weight training are popular training methods for maximizing time-efficiency, and are purported to deliver greater physiological benefits faster than traditional training methods. Adding interval training into a circuit weight-training workout may further enhance the benefits of circuit weight training by placing increased demands upon the cardiovascular system. Our purpose was to compare acute effects of three circuit weight training protocols 1) traditional circuit weight training, 2) aerobic circuit weight training, and 3) combined circuit weight-interval training on blood lactate (BLA), heart rate (HR), and ratings of perceived exertion (RPE). Eleven recreationally active women completed 7 exercise sessions. Session 1 included measurements of height, weight, estimated VO2max, and 13 repetition maximum (RM) testing of the weight exercises. Sessions 2-4 were held on non-consecutive days for familiarization with traditional circuit weight training (TRAD), aerobic circuit weight training (ACWT), and combined circuit weight-interval training (CWIT) protocols. In sessions 5-7, TRAD, ACWT, and CWIT were performed in a randomized order ≥ 72 hr apart for measures of BLA, HR, and RPE at pre-exercise and following each of three mini-circuit weight training stations. Repeated-measures ANOVAs yielded significant interactions (p < 0.05) in BLA, HR, and RPE. Combined circuit weight-interval training (CWIT) produced higher BLA (7.31 ± 0.37 vs. TRAD: 3.99 ± 0.26, ACWT: 4.54 ± 0.31 mmol.L-1), HR (83.51 ± 1.18 vs. TRAD: 70.42 ± 1.67, ACWT: 74.13 ± 1.43 beats.min-1) and RPE (8.14 ± 0.41 vs. TRAD: 5.06 ± 0.43, ACWT: 6.15 ± 0.42) at all measures. Aerobic circuit weight training (ACWT) elicited greater RPE than traditional circuit weight training (TRAD) at all measures. Including combined circuit weight-interval training (CWIT) workouts into exercise programming may enhance fitness benefits and maximize time-efficiency more so than traditional circuit training methods.

Key points

  • Combining circuit weight training with interval training requires people to exercise at a higher intensity.
  • The moderately trained can obtain fitness benefits from including interval training as part of a circuit weight training protocol.
  • Merging circuit weight training with interval training may be a desirable option for those with limited time to exercise.
Key words: Interval training, repetition maximum, resistance training  相似文献   

6.

Introduction

One of the greatest problems associated with continuous renal replacement therapy (CRRT) is the early clotting of filters. A literature search revealed three case reports of lipemic blood causing recurrent clotting and reduced CRRT circuit survival time in adult patients, but no reports of cases in children.

Diagnosis/treatment

A 23-month-old male infant with Martinez–Frias syndrome and multivisceral transplant was admitted to the hospital with severe sepsis and hemolytic anemia. He developed acute kidney injury, fluid overload and electrolyte imbalances requiring CRRT and was also administered total parenteral nutrition (TPN) and fat emulsion. The first circuit lasted 60 h before routine change was required. The second circuit showed acute clotting after only 18 h, and brownish-milky fluid was found in the circuit tubing layered between the clotted blood. The patient’s serum triglyceride levels were elevated at 988 mg/dL. The lipid infusion was stopped and CRRT restarted. Serum triglyceride levels improved to 363 mg/dL. The new circuit lasted 63 h before routine change was required.

Conclusion

Clotting of CRRT circuits due to elevated triglyceride levels is rare and has not been reported in the pediatric population. Physicians should be mindful of this risk in patients receiving TPN who have unexpected clotting of CRRT circuits.
  相似文献   

7.
Infants requiring CRRT present a unique challenge due to the large circuit volume to blood volume ratio. Blood priming is often used, but some patients can become unstable during the initiation of CRRT due to electrolyte and acid-base imbalance. We postulated that using Z-BUF we could normalize electrolytes and improve the acid base status of the prime prior to patient connection. To test this we set up a circuit using the Baxter BM-25 CRRT pump, a polysulfone or AN-69 membrane, and a three-way stopcock. The circuit was primed with a 60/40 mix of expired autologous donor pRBCs and 5% albumin. The modalities of CVVH, CVVHD, and CVVHDF were compared for relative efficacy. Electrolytes, lactate, pH, cytokines (TNF-, IL-1, bradykinin, and IL-6) were measured. Plasma hemoglobin levels were also measured before and after the Z-BUF procedure. Bradykinin production and elimination in AN-69 membrane circuits were assessed. All lab values equilibrated by 35 minutes. All CRRT modalities were equally efficacious for Z-BUF. Cytokine production or significant hemolysis was not found. In addition, no bradykinin accumulation occurred in AN-69 membrane-containing circuits. We conclude that Z-BUF is a simple and effective way to normalize electrolyte and acid-base status in the CRRT circuit when blood priming is required.  相似文献   

8.
Two cases are presented which illustrate the disastrous consequences possible when an anaesthetic breathing circuit is obstructed by a foreign body. Despite reports of previous similar cases, work practices and equipment manufacture or design continue to allow for such events to occur. The importance of both pre-anaesthetic testing of the entire circuit including attachments such as the tracheal tube connector and filters, and the removal of these parts should obstruction occur, is emphasised. Use of "clear" transparent breathing circuit components and opaque or brightly coloured packaging and caps which could potentially cause obstruction should decrease the incidence and facilitate the diagnosis of this problem.  相似文献   

9.
10.
Modified ultrafiltration is an important technique to concentrate the patient's circulating blood volume and the residual whole blood in the extracorporeal circuit post-cardiopulmonary bypass. The Hemobag system is a device cleared by the US Food and Drug Administration and represents a novel and safe modification of traditional modified ultrafiltration systems. It is quick and easy to operate by the perfusionist during the hemoconcentration process. Hemoconcentration is accomplished by having the Hemobag "recovery loop" circuit separate from the extracorporeal circuit. This allows the surgeons to continue with surgery, decannulate, and administer protamine simultaneously while the Hemobag is in use. The successful use of the Hemobag in a Jehovah's Witness patient has not been previously described in the literature. This case report describes how to set up and operate the Hemobag in a Jehovah's Witness patient undergoing cardiac surgery that requires an extracorporeal circuit.  相似文献   

11.

Purpose

To develop a predictive model for circuit clotting in patients with continuous renal replacement therapy (CRRT).

Methods

A total of 425 cases were selected. 302 cases were used to develop a predictive model of extracorporeal circuit life span during CRRT without citrate anticoagulation in 24 h, and 123 cases were used to validate the model. The prediction formula was developed using multivariate Cox proportional-hazards regression analysis, from which a risk score was assigned.

Results

The mean survival time of the circuit was 15.0 ± 1.3 h, and the rate of circuit clotting was 66.6 % during 24 h of CRRT. Five significant variables were assigned a predicting score according to the regression coefficient: insufficient blood flow, no anticoagulation, hematocrit ≥0.37, lactic acid of arterial blood gas analysis ≤3 mmol/L and APTT < 44.2 s. The Hosmer–Lemeshow test showed no significant difference between the predicted and actual circuit clotting (R 2 = 0.232; P = 0.301).

Conclusions

A risk score that includes the five above-mentioned variables can be used to predict the likelihood of extracorporeal circuit clotting in patients undergoing CRRT.  相似文献   

12.
A versatile closed circuit with new features is described. Itmay be used in a totally closed manner, without continuous gasinflow. As gas is absorbed from the circuit, it is replacedthrough a demand valve. Facilities for continuous gas inputand use of a ventilator are included, and one control convertsit to a non-rebreathing circuit. The circuit has excellent mechanicalcharacteristics in all modes, and has been used extensivelyin routine clinical practice. *Present addresses: National Institute of Medical Research,The Ridgeway, Mill Hill, London. Present addresses: Regional Postgraduate Institute for Medicineand Dentistry, The Medical School, The University, Newcastleupon Tyne.  相似文献   

13.
To determine the effects of red cell separation and ultrafiltration on heparin concentration. Prospective study. University-affiliated, pediatric medical center. Thirty-one children undergoing cardiac surgery. Blood sampled for heparin concentration and coagulation tests. Thirteen infants underwent modified veno-venous ultrafiltration (UF) after cardiopulmonary bypass (CPB). In addition, residual blood in the CPB circuit was hemoconcentrated by UF and reinfused (UF group). Heparin concentration increased from 2.0 ± 0.6 to 2.5 ± 0.8 U/mL, following modified UF; while activated coagulation time (ACT) decreased from 701 ± 177 to 627 ± 107 seconds. Heparin concentration of CPB circuit residual increased from 1.9 ± 0.7 to 3.1 ± 1.0 U/mL.In 18 children (older than 1 year old), the residual blood in the CPB circuit was hemoconcentrated by cell separation (CS) and reinfused (CS group). Heparin concentration of CPB circuit residual decreased from 2.6 ± 0.6 to 0.3 ± 0.2 U/mL. After reinfusion, patient heparin concentration remained unchanged at <0.05 U/mL. Thrombin time increased from 28 ± 6 to 48 ± 29 seconds and did not correlate with H. The plasma concentration of heparin increased after veno-venous modified UF of the patient. Heparin concentration also increased after UF of residual CPB circuit blood. In contrast, circuit blood hemoconcentrated by CS contained minimal heparin, and, when infused, did not increase patient's heparin concentration. ACT and thrombin time did not correlate with heparin concentration.  相似文献   

14.
A vaporizing system for closed circuit "programmed" anaesthesiais described. Despite its location within the circuit, the vaporizercontrols directly the input of volatile anaesthetic agents irrespectiveof fluctuations in ventilation of the anaesthetized subject.It is interfaced easily with electronic controllers and hasan accuracy approaching 1.0% under laboratory conditions. Duringexperimental anaesthesia, it maintained stable end-tidal concentrationsof halothane at 1.2 MAC (the intended value) despite wide variationsin ventilation. Present address: Department of Anaesthetics, Alfred Hospital,Prahran, Victoria 3181, Australia  相似文献   

15.
An essential drawback of the conventionally used semi-closed circuit is its poor control of the inflated volume. An intermittently closed circuit, i.e. a circuit which is closed during each inflation, but open with low resistance during each expiration, is described. It displays the following advantages: better control of die volume inflated into the lungs widi each bag compression; early recognition of changes in resistance to inflation; more optimal pressure conditions in the respiratory system and dierefore also in die chest; no adjustment of die pop-off valve is necessary. The function of die intermitter, die incorporation of which converts die semi-closed circuit to an intermittently closed circuit, is described.
This circuit can be improvised from generally available anaesdiesia component.

ZUSAMMENFASSUNG


Ein wesentlicher Nachteil der konventionell verwendeten halbgeschlossenen Systeme ist die schlechte Kontrolle iiber das eingeblasene Volumen. Es wird ein intermittierend geschlossenes System beschrieben, d. h. ein Kreissystem, das bei jeder Beatmung geschlossen, jedoch wahrend jeder Exspiration bei niedrigem Widerstand offen ist. Es bringt die nachstehenden Vorteile: bessere Kontrolle des Volumens, das bei jeder Atembeutelkompression in die Lunge geblasen wird; friihe Erkennung der Widerstandsanderungen bei der Beatmung; opti-malere Druckbedingungen im Atemsystem und damit auch im Thorax; es sind keine Adjustierungen des Uberlaufventils notwendig. Die Funktion des Unter-brechers, dessen Einbeziehung das halbgeschlossene in ein intermittierend geschlossenes System verwandelt, wird beschrieben.
Dieses Kreissystem kann aus allgemein erhaldichen Anaesthesiegeratbe-standteilen improvisiert werden.  相似文献   

16.
According to the Baddeley-Hitch model, phonological and visuospatial representations are separable components of working memory (WM) linked by a central executive. The traditional view that the separation reflects the relative contribution of the 2 hemispheres (verbal WM--left; spatial WM--right) has been challenged by the position that a common bilateral frontoparietal network subserves both domains. Here, we test the hypothesis that there is a generic WM circuit that recruits additional specialized regions for verbal and spatial processing. We designed a functional magnetic resonance imaging paradigm to elicit activation in the WM circuit for verbal and spatial information using identical stimuli and applied this in 33 healthy controls. We detected left-lateralized quantitative differences in the left frontal and temporal lobe for verbal > spatial WM but no areas of activation for spatial > verbal WM. We speculate that spatial WM is analogous to a "generic" bilateral frontoparietal WM circuit we inherited from our great ape ancestors that evolved, by recruitment of additional left-lateralized frontal and temporal regions, to accommodate language.  相似文献   

17.
The "AMBU-CPAP system" is a new, simple and reliable circuit for administering positive airway pressure in spontaneous-breathing therapy. Some disadvantages of other CPAP devices are avoided, and the use of the system with low gas flow is possible. The change of airway pressure during respiration was measured and was found to be less than 5 millibars.  相似文献   

18.
The addition of a continuous Flow System to the circuit of a volume cycled respirator results in an additional IMV option and shows excellent performance for this purpose. The insertion of a bacterial filter into this modified circuit resulted in a dangerous increase of airway pressures after 54 "running hours" for that filter. Test series revealed an insufficient air transmission through the filter, caused by the water vapour-saturated inspiratory gas mixture, which is necessary in long term ventilation. Furthermore it was demonstrated that wet bacterial filters cause malfunction of SIMV systems due to interference with the demand valve responsible for proper air supply. The routine use of a bacterial filter placed in the expiratory branch results in higher risks in an already risky artificial ventilation system and use-nonuse relationships seem to be questionable.  相似文献   

19.
Purpose The properties of two new-generation CO2 absorbents, Amsorb Plus (Armstrong Medical, Coleraine, UK) and Drägersorb Free (Dräger, Lübeck, Germany), were compared with those of Amsorb (Armstrong Medical) and Sodasorb II (W.R. Grace, Lexington, MA, USA).Methods The concentration of compound A produced by each absorbent was determined in a low-flow circuit containing sevoflurane, and the CO2 absorption capacity of the absorbent was measured. The circuit contained 1000g of each absorbent and had a fresh gas (O2) flow rate of 1l·min–1 containing 2% sevoflurane. CO2 was delivered to the circuit at a flow rate of 200ml·min–1.Results The maximum concentrations of compound A were 2.2 ± 0.0, 2.3 ± 0.3, 2.2 ± 0.2, and 23.5 ± 1.5ppm (mean ± SD) for Amsorb Plus, Drägersorb Free, Amsorb, and Sodasorb II, respectively. The maximum concentration of compound A for Sodasorb II was significantly higher than those for the other absorbents (P < 0.01). The CO2 absorption capacities (time taken to reach an inspiratory CO2 level of 2mmHg) were 1023 ± 48, 1074 ± 36, 767 ± 41, and 1084 ± 54min, respectively, and the capacity of Amsorb was significantly lower than that of the other absorbents (P < 0.01).Conclusion The new-generation carbon dioxide absorbents, Amsorb Plus and Drägersorb Free, produce a low concentration of compound A in the circuit while showing sufficient CO2 absorption capacity.  相似文献   

20.
The most proximal site to sample end-tidal CO2 with reasonable accuracy in infants during pulmonary ventilation using a Mapleson D circuit remains controversial. The utilisation of high fresh gas flow near the site of gas sampling dilutes the expired gas and causes an underestimation of end-tidal CO2. In this study a laboratory model was used to identify, qualitatively and quantitatively, the most proximal site in the Mapleson D circuit where the measurement of end-tidal CO2 is not influenced by mixing with fresh gas. A fresh gas flow rate of between 2 and 15 L · min?1 with a respiratory rate of 20–30 · min?1 and a tidal volume of 30–100 ml · min?1 was evaluated. This experiment was divided into two parts. Firstly, an infant lung model was used to visualize the site of mixing between fresh gas and smoke-labelled exhaled gas. Secondly, fresh gas flow and expired gas flow were controlled and the end-tidal CO2 concentration was measured along the length of the anaesthetic circuit to identify the site of mixing of fresh gas and expired gas during steady-state conditions. Three expired gas flows were studied at six fresh gas flows. In all our studies, the rate of fresh gas flow and expired gas flow influenced the site of mixing and degree of dilution but no mixing was observed distal to the point at which the endotracheal tube connector narrows to the diameter of the endotracheal tube (P < 0.05). This laboratory study allows us to suggest that the most proximal and acceptably accurate site to sample end-tidal Co2 in infants during ventilation with the Mapleson D circuit is at the point of narrowing of the endotracheal tube connector with the endotracheal tube.  相似文献   

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