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1.
A 4.2-kg full-term male infant underwent treatment of acuterespiratory distress as a result of gross bilateral pneumothoraces,pneumomediastinum and interstitial emphysema. When a trial ofcontinuous positive airway pressure failed conventional intermittentpositive pressure ventilation was instituted, but this alsofailed to achieve satisfactory ventilation at a respiratoryfrequency of 60 b.p.m. while producing peak airway pressuresof 30cmH2O. High frequency positive pressure ventilation wasinstituted with a Siemens 900C ventilator delivering a minutevolume of 3 litre min-1 at a respiratory frequency of 72b.p.m.,while registering peak airway pressures in the range of 20–23cmH2O.During the first 30 min of this regimen the patient's conditionimproved such that FIO2 was decreased to 0.6. Six hours laterFIO2 was decreased to 0.55 and the inspired minute volume to2.8 litre min–1 with a further decrease in peak airwaypressure. The infant was maintained on high frequency positivepressure ventilation for a total of 42 h, and following weaningmade an uneventful recovery. In another newborn infant, weight1.9 kg, the measurement of airway pressure at the distal endof the tracheal tube and gas flow in the inspiratory limb ofthe respiratory circuit established that the tracheal peak airwaypressure was 10 cm H2O less that the pressure registered onthe ventilator. The 900C ventilator produced a pattern of highfrequency low pressure ventilation, with sustained PEEP, whichclosely resembles the defined pattern of HFPPV.  相似文献   

2.
Five patterns of ventilation have been compared in dogs: (1)spontaneous ventilation at ambient pressure (SV); (2) intermittentpositive pressure ventilation (IPPV); (3) spontaneous ventilationat 0.98 kPa positive airway pressure, delivered from a non-rebreathingcircuit incorporating a 5-litre reservoir bag and fresh-gasflow of twice the minute volume (CPAP (bag)); (4) spontaneousventilation at 0.98 kPa positive airway pressure, with the reservoirbag replaced by a weighted bellows (CPAP (bellows)) and (5)IPPV with 0.98 kPa positive end-expiratory pressure (CPPV).CPAP significantly decreased the rate of respiration comparedwith SV. CPAP (bellows) resulted in a significant increase intidal volume. Mean oesophageal pressure, right atrial pressure,pulmonary wedge pressure and pulmonary artery pressure increasedduring IPPV, CPAP (bag), CPAP (bellows), and CPPV compared withSV. There were no significant changes in mean systemic arterialpressure, cardiac output, PaO2, PaCO2, CaO2, (CaO2CO2),(PAO2, — PaO2) or pulmonary venous admixture. Under theconditions of this study oxygen transport was not altered bypositive airway pressure ventilation. *Also Department of Anaesthesia, Hammersmith Hospital.  相似文献   

3.
M. Morris 《Thorax》1999,54(9):790-795
BACKGROUND: Lung volume measurement by nitrogen washout is widely used in infants, though a lack of accuracy and changes of calibration over time have been reported. The potential sources of error were explored in order to increase the accuracy and reliability of the technique. METHODS: A commercial system for nitrogen washout and a 0.5 litre calibrating syringe as a lung model were used to perform over 2000 in vitro washouts, including simulated rapid breathing, shallow breathing, periodic breathing, sighs, and brief apnoeas. A constant 10 l/min bias flow of oxygen and extended equipment warming times were employed. A collapsible breathing bag was incorporated into the washout circuit. Following a single two point calibration, known air volumes from 42 ml to 492 ml were measured by nitrogen washout over a 14 hour period. The flow waveform in the nitrogen mixing chamber during a washout in vitro, with and without the breathing bag in the circuit, was also studied. RESULTS: The mean coefficient of variation of all volumes was 0.66%. The mean difference between measured and known volumes was 0.30 ml (95% confidence interval (CI) -0.18 to 0.79). This difference was not statistically significant (p = 0.22). The mean percentage error was -0.1% (range -0.47% to 0.46%). Nitrogen calibration remained stable for 14 hours. Without the breathing bag flow transients were frequent in the mixing chamber during in vitro washout. CONCLUSIONS: This technique increases the accuracy in vitro and the precision in vivo of volume measurement by nitrogen washout. Sources of potential errors including baseline drifting and inadequate equipment warming times were identified. The breathing bag acted as a buffer reservoir, preventing large swings in flows within the nitrogen mixing chamber during washouts, and should be an integral component of the nitrogen washout circuit.  相似文献   

4.
A PRELIMINARY CLINICAL STUDY OF CT1341--A STEROID ANAESTHETIC AGENT   总被引:2,自引:0,他引:2  
The effects of a new steroid anaesthetic agent (CT1341) werestudied in twenty volunteers divided into three groups. In groupI, serial measurements were made of heart rate, blood pressureand respiratory rate. In group II, detailed haemodynamic studieswere made in patients undergoing diagnostic cardiovascular investigations.These studies included measurement of cardiac output, strokevolume and arterial blood gases. In group III, time from inductionto "true recovery" was measured following a single intravenousinjection of the drug. This agent produced a stable anaestheticstate in all cases. Anaesthesia was characterized by a risein respiratory rate and pulse rate with a slight fall in systolicand diastolic blood pressure. A significant fall in Pao2 occurredin those patients breathing air. The mean recovery time in sixpatients was 24.3 min. CT1341 produced safe and stable anaesthesiain all twenty cases and is worthy of further clinical trial.  相似文献   

5.
Background. Tracheal pressure (Ptr) is required to measure theresistance of the tracheal tube and the breathing circuit. Ptrcan either be measured with a catheter or, alternatively, calculatedfrom the pressure–flow data available from the ventilator. Methods. Calculated Ptr was compared with measured Ptr duringcontrolled ventilation and assisted spontaneous breathing in18 healthy and surfactant-depleted piglets. Their lungs wereventilated using different flow patterns, tidal volumes (VT)and levels of positive end-expiratory pressure. Results. In terms of the root mean square error (RMS), indicatingthe average deviation of calculated from measured Ptr, the differencebetween calculated and measured Ptr was 0.6 cm H2O (95%CI 0.58–0.65)for volume-controlled ventilation; 0.73 cm H2O (0.72–0.75)for pressure support ventilation; and 0.78 cm H2O (0.75–0.80)for bi-level positive airway pressure ventilation. Conclusion. The good agreement between calculated and measuredPtr during varying conditions, suggests that calculating Ptrcould help setting the ventilator and choosing the appropriatelevel of support. Br J Anaesth 2003; 91: 239–48  相似文献   

6.
In order to explore new types of jet ventilation, we testeda tracheal gas injection tube (TGIT) which included six thincapillaries and provided high pressure injection. The drivingpressure was chosen to yield a plateau of inspiratory trachealpressure of 10 cm H2O. An original controller was built to monitorspirometry and trigger injection in order to deliver both pressurecontrolled ventilation (PCVTGIT) and a new mode of inspiratorypressure support jet ventilation (IPSJQU). The PVCTGn mode maintainedthe same end-tidal carbon dioxide concentration as conventionalventilation with the same tidal and minute ventilation. We studied10 patients after abdominal surgery. During spontaneous breathing,the patients were allowed to breathe through the tube, successivelywith and without IPSTGIT. IPSTGIT compared with spontaneousbreathing increased minute ventilation (from 5.7 (SD 1.6) to7.1 (1.7) litre min) (P < 0.001). It reduced the totalwork of breathing (from 0.625 (0.223) to 0.263 (0.151) J litre,respectively) (P < 0.01) and the occlusion pressure (from2.62 (1.28) to 1.36 (0.74) cm H2O, respectively) (P < 0.01).It is concluded that this TGIT used with a specific system forsensing and triggering ventilation allows inspiratory pressuresupport during low frequency jet ventilation.  相似文献   

7.
A case of cardiac arrest is presented which was caused by improper connection of a modified Mapleson D circuit (Bain breathing circuit). Excessive enternal deadspace was created by interchanging the gas inflow line and the attachment for an airway pressure manometer. This resulted in a marked respiratory acidosis, clinically undetected until the concomitant hypoxia produced a severe cardiac depression and arrest. The sequence of events was reproduced in a dog under comparable anaesthetic conditions. In order to avoid this error it is recommended to permanently fuse the connecting piece placed in the circuit with the tubing leading to the airway pressure manometer of the respirator.  相似文献   

8.
An anaesthetic circuit is described, which fulfils the following requirements: 1) It is suitable for patients of all age groups; 2) There is no expiratory resistance; 3) There is no anaesthetic gas exposure risk to operating room staff; 4) The change from spontaneous to controlled respiration can be made without the necessity of access to the patient attachment; 5) It is easy to handle and clean.
The system is a modified Magill circuit, consisting of a corrugated tube with breathing bag, relief valve, and dumping valve. Gas evacuation is performed continuously through an ejector flowmeter connected to a narrow branch tube at the patient attachment.
The flow requirement was calculated by analyses of the system and was investigated using 10 conscious volunteers (spontaneous respiration) and five anaesthetized patients (controlled respiration). Significant rebreathing was not seen with a fresh gas flow exceeding the basal respiratory minute volume requirement by 35%.  相似文献   

9.
Two modes of combining spontaneous breathing and mechanical ventilation are already in use: periodic mechanical support always followed by a period of spontaneous breathing (intermittent mandatory ventilation; IMV) and mechanical support of each spontaneous breath (inspiratory assistance; IA). Biphasic positive airway pressure (BIPAP), in contrast, is based on neither of the above mentioned principles. It is rather a mixture of pressure controlled (PC) ventilation and spontaneous breathing, which is unrestricted in each phase of the respiratory cycle. The BIPAP circuit switches between a high (Phi) and a low (Plo) airway pressure level in an adjustable time sequence. At both pressure levels the patient can breathe spontaneously in a continuous positive airway pressure system (CPAP). The volume displacement caused by the difference between Phi and Plo and the BIPAP frequency (F) contribute the mechanical ventilation to total ventilation. Duration of the Phi and the Plo phases can be independently adjusted. Similar to the I:E ratio during controlled ventilation, the phase time ratio (PhTR) is calculated as the ratio between the durations of the two pressure phases. A PhTR greater than 1:1 is called IR-BIPAP. A BIPAP system can be set up either as a continuous flow system, or as a demand valve system. A continuous-flow BIPAP system consists of a high-flow CPAP system, a reservoir bag, and a pneumatically controlled membrane valve in the expiratory limb. A magnetic valve operated by an impulse generator switches between Phi and Plo, controlling the pop-off pressures of the expiratory valve.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
The cardiorespiratory effects of intermittent positive pressureventilation with zero end-expiratory pressure (IPPV), continuouspositive airway pressure breathing (CPAP) and spontaneous breathing(SR) were studied in 11 patients 3–20 h after open-heartsurgery. The transition from IPPV to CPAP resulted in a significantreduction in tidal volume and significant increases in respiratoryfrequency, PaCO2, oxygen transport and mean arterial pressure,but there were no significant changes in cardiac output or PaO2.There were no significant differences in any of the measurementsbetween CPAP and SR. *Present address: Department of Anaesthesia, Athens Hospitalfor Chest Diseases, Athens, Greece.  相似文献   

11.
Hyperpnea increases anesthetic elimination but is difficult to implement with current anesthetic circuits without decreasing arterial PCO2. To circumvent this, we modified a standard resuscitation bag to maintain isocapnia during hyperpnea without rebreathing by passively matching inspired PCO2 to minute ventilation. We evaluated the feasibility of using this apparatus to accelerate recovery from anesthesia in a pilot study in four isoflurane-anesthetized dogs. The apparatus was easy to use, and all dogs tolerated being ventilated with it. Under our experimental conditions, isocapnic hyperpnea reduced the time to extubation by 62%, from an average of 17.5 to 6.6 min (P = 0.012), but not time from extubation to standing unaided. This apparatus may provide a practical means of applying isocapnic hyperpnea to shorten recovery time from volatile anesthetics. IMPLICATIONS: A simple modification to a standard resuscitation bag allows one to increase ventilation without decreasing blood carbon dioxide levels. In dogs, we confirmed that this circuit can be used to accelerate the elimination of and recovery from volatile anesthetics.  相似文献   

12.
Blanshard HJ  Milne MR 《Anaesthesia》2004,59(2):177-179
The reservoir bag on the anaesthetic breathing circuit is a safety feature that can protect the patient. It is highly distensible, pressures within the breathing circuit rarely exceeding 3.9 kPa (40 cmH2O) even when the adjustable pressure-limiting valve is inadvertently left closed. In providing a safe latex-free environment in our anaesthetic rooms, the traditional latex rubber reservoir bag is substituted by a latex-free one. To investigate the safety features of several latex-free reservoir bags already in use in our hospital, we assessed the in-circuit pressures obtained at stepped fresh gas flows using a lung simulator. Four out of five of the latex-free bags exceeded pressures of 4.4 kPa (45 cmH2O), raising the possibility that, in trying to avoid an occupational hazard, we might be compromising patient safety. We found that, of the five latex-free systems we tested, only the Intersurgical complete respiratory system provided an adequate safety mechanism for the patient and thus did not potentially compromise patient safety.  相似文献   

13.
Mechanical ventilation of the anesthetized infant requires careful attention to equipment and ventilator settings to assure optimal gas exchange and minimize the potential for lung injury. Apparatus dead space, defined as dead space resulting from devices placed between the endotracheal tube and the Y‐piece of the breathing circuit, is the primary source of dead space controlled by the clinician. Due to the small tidal volumes required by infants and neonates, it is easy to create excessive apparatus dead space resulting in unintended hypercarbia or increased minute ventilation in an effort to achieve a desirable PCO2. The goal of this review was to evaluate the apparatus that are commonly added to the breathing circuit during anesthesia care, and develop recommendations to guide the clinician in selecting apparatus that are best matched to the clinical goals and the patient's size. We include specific recommendations for apparatus that are best suited for different size pediatric patients, with a particular focus on patients <5 kg.  相似文献   

14.
The effect of dantrolene on ventilation and ventilatory muscleactivity was evaluated in spontaneously breathing anaesthetizeddogs. When administered as a bolus of 7.5 mg kg–1 i.v.,dantrolene caused hypercapnia. Under isocapnic conditions, withend-tidal Pco2 maintained at 8.1 (SEM 0.3) kPa by adjustinginspired carbondioxide, dantrolene decreased tidal volume from475 (66) to 254 (46) ml and breathing rate from 21 (4) to 15(3) b.p.m. (P < 0.01 for both). Occlusion pressure was reduced,but the rate of rise of the diaphragm and intercostal EMG wereunchanged and peak activity increased only as a result of prolongationof inspiration. Respiratory variables returned gradually tobaseline values 1 h after dantrolene administration. Phrenicnerve stimulation revealed a marked reduction in the abilityof the diaphragm to generate pressure, particularly at low frequenciesof stimulation. Only partial recovery was observed after 1 h.It is concluded that dantrolene causes hypoventilation in theanaesthetized dog when given in large doses i.v.  相似文献   

15.
Heat and moisture exchangers (HMEs) humidify, warm and filter inspired gas, protecting patients and apparatus during anaesthesia. Their incorporation into paediatric anaesthetic breathing systems is recommended. We experienced delays in inhalational induction whilst using a Mapleson F breathing system with an HME. We have demonstrated that the HME significantly alters gas flow within the breathing system. Approximately half of the fresh gas flow is delivered to the patient, the remainder being wasted into the expiratory limb of the breathing system. We suggest that the HME should be removed from the Mapleson F breathing system until inhalational induction is complete, or that the reservoir bag is completely occluded until an effective seal is obtained with the mask.  相似文献   

16.
The effects of selective mechanical ventilation of dependentlung regions were studied in anaesthetized horses (mean weight486 kg) in dorsal recumbency. Blood-gas measurements were performedwith the horse in the lateral position during spontaneous breathing(before selective intubation) and in dorsal recumbency duringspontaneous breathing, general mechanical ventilation, and spontaneousbreathing +selective mechanical ventilation. Arterial oxygentension (PaO2) was 32.3 kPa in the lateral position during spontaneousbreathing with a high inspired oxygen fraction (FlO2 >92%).In dorsal recumbency PaO2 decreased to 10.9 kPa during spontaneousbreathing and was not significantly affected by general mechanicalventilation (PaO2 12.6 kPa). The institution of selective mechanicalventilation with a selective positive end-expiratory pressure(PEEP) of 20 cm H2O caused a marked increase in PaO2 to an averageof 35.3 kPa. It is concluded that selective intubation of dependentregions in the diaphragmatic lobes is a feasible procedure andthat selective mechanical ventilation with PEEP markedly improvesarterial oxygenation in the anaesthetized horse in dorsal recumbency.  相似文献   

17.
Perforation of the cuff of the endotracheal tube peroperatively is a very serious problem, especially when it occurs in a patient prone on an orthopaedic table. This is even more dramatic when the patient is not breathing spontaneously and he cannot be turned over to be reintubated. Given the unusual character of this situation, an apparatus has been designed to keep the cuff inflated permanently. It was a circuit consisting of a manual pressure valve, flexible tubing, a peripheral catheter and the cuff supply tube. The gas used was medical air at 3 bar pressure. This method proved perfectly safe and efficient, the operation having continued without reintubation.  相似文献   

18.
In six dogs anaesthetized with Althesin, minute ventilation,respiratory rate, tidal volume, PaO2 and PaCO2 were measuredwhile breathing air (F1O2 = 0.21), and then after correctionof hypoxaemia (F1O2 = 0.35), and again while breathing 100%oxygen (F1O2= 1.00). The administration of 35% oxygen correctedthe hypoxaemia (PaO2 = 8.98 ± 0.76 kPa in air; PaO2 =16.39 ± 1.59 kPa with 35% oxygen), but produced a significantand sustained depression of ventilation. The administrationof 100% oxygen induced a further significant and sustained decreasein ventilation. It is concluded that hypoxaemia is not necessaryfor the ventilatory depressant action of oxygen in the anaesthetizeddog and that, under Althesin anaesthesia, peripheral arterialchemoreceptors are active up to high PaO2 values.  相似文献   

19.
A device to modify the physiological impact of the abrupt transition of IPPV and PEEP to spontaneous breathing is described. It consists of a coaxial breathing system with a spring-loaded reservoir bag and underwater pressure limit. Electric alarms are incorporated.  相似文献   

20.
An interdisciplinary working group from the German Society of Hospital Hygiene (DGKH) and the German Society for Anesthesiology and Intensive Care (DGAI) worked out the following recommendations for infection prevention during anesthesia by using breathing system filters (BSF). The BSF shall be changed after each patient. The filter retention efficiency for airborne particles is recommended to be >99% (II). The retention performance of BSF for liquids is recommended to be at pressures of at least 60 hPa (=60 mbar) or 20 hPa above the selected maximum ventilation pressure in the anesthetic system.The anesthesia breathing system may be used for a period of up to 7 days provided that the functional requirements of the system remain unchanged and the manufacturer states this in the instructions for use. The breathing system and the manual ventilation bag are changed immediately after the respective anesthesia if the following situation has occurred or it is suspected to have occurred: Notifiable infectious disease involving the risk of transmission via the breathing system and the manual bag, e.g. tuberculosis, acute viral hepatitis, measles, influenza virus, infection and/or colonization with a multi-resistant pathogen or upper or lower respiratory tract infections. In case of visible contamination e.g. by blood or in case of defect, it is required that the BSF and also the anesthesia breathing system is changed and the breathing gas conducting parts of the anesthesia ventilator are hygienically reprocessed.Observing of the appropriate hand disinfection is very important. All surfaces of the anesthesia equipment exposed to hand contact must be disinfected after each case.  相似文献   

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