Imposed work of breathing and methods of triggering a demand-flow, continuous positive airway pressure system

Banner, Michael J.; Blanch, Paul B.; Kirby, Robert R.

doi:10.1097/00003246-199302000-00007

Cited by 68 publications

(24 citation statements)

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“…For the flow and the ventilation, VELA was more accurate than other ventilators such as LTV1200. In this context, Banner et al have shown that the ventilator used in the acute phase was more precise and had a better function than the ventilator used in the chronic phase [13].…”

Section: Discussionmentioning

confidence: 99%

Angle Effect to Dropping of Dew in Closed Suction Catheters

Doi¹,

Doi²,

Yaegashi³

et al. 2018

Health

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Intratracheal aspiration in a patient on ventilation is generally performed using a catheter. Of late, closed suction systems have been used more frequently than open systems. To remove tracheal secretions through the intratracheal tube, catheter suction is used, and the suction catheter may be of the closedor open-type. The catheters are cleaned by flushing with sterile 0.9% saline, resulting in dropping of dew. This phenomenon is caused by some factors: influence of flow, clogging of the suction tube, problem of manipulation of flushing and angle between the intubation tube and the connection port. But this dropping has not yet been investigated. In this study, we focused at this angle and we used the test lung which is simulated machine on behalf of patient. We consider two situations adult and child, also two types of catheters Eco-Cath and Ty-care. In child case we consider elbow-type suction catheters and Y-connector type. The angle was set at 0˚, 20˚, 40˚, 60˚, and 90˚, and we observed the difference between Eco-Cath and Ty-care. In adults difference is significant (p  0.001), In 90˚ between Tracheal intubation and Tracheotomy (p ≈ 0.26). In child difference is significant (p  0.001), In 90˚ between Tracheal intubation and Tracheotomy (p ≈ 0.15). In child case we observed dependency of angle on various conditions too. The relation of the angle and dew was clarified.

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Section: Discussionmentioning

confidence: 99%

Angle Effect to Dropping of Dew in Closed Suction Catheters

Doi¹,

Doi²,

Yaegashi³

et al. 2018

Health

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“…Because of the shape of the humidifier, this test is often referred to as a T-piece trial and can last up to two hours in order to test the patient's tolerance to spontaneous breathing (1,2). However, the endotracheal tube has a finite respiratory resistance (3)(4)(5)(6)(7), which could theoretically represent an additional load and impair the patient's ventilation.…”

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confidence: 99%

Contribution of the Endotracheal Tube and the Upper Airway to Breathing Workload

Straus

Louis²,

Isabey³

et al. 1998

Am J Respir Crit Care Med

158

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The influence of the endotracheal tube (ETT) during a T-piece trial remains controversial. Our aim was to compare the work of breathing of 14 successfully extubated patients at the end of a 2-h trial (T) and after extubation (E) of the trachea, and to assess, using the acoustic reflection method, the resistance of the endotracheal tube and of the supraglottic airway as well as their related work. We found that the work of breathing of the patients was identical between T and E (1.72 +/- 0.59 versus 1.63 +/- 0.45 J/L; p = 0.50 and 23.5 +/- 10.6 versus 22.6 +/- 9.7 J/min; p = 0.70). There was no significant difference between the beginning and the end of the T-piece trial (1.57 +/- 0.53 versus 1.72 +/- 0.59 J/ L, p = 0.10). The work caused by the ETT amounted to 11.0 +/- 3.9% of the total work of breathing. The supraglottic airway resistance was in the normal range and was significantly smaller than the endotracheal tube resistance (0.79 +/- 0.4 versus 1.43 +/- 0.31 cm H2O x s/L; p = 0.008, flow = 0.25 L/s). We conclude that a 2-h trial of spontaneous breathing through an endotracheal tube well mimics the work of breathing performed after extubation, in patients who pass a weaning trial and do not require reintubation.

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“…WOB may be considerably elevated in the intubated and spontaneously breathing patient due to the addition of imposed WOB and increased elastic and flow resistive forces from underlying lung disease. Imposed WOB is the flow resistive work undertaken by the patient to spontaneously breath through the breathing apparatus (endotracheal tube, respiratory circuit and demand valve) and can be calculated from the area of the inspiratory loop when carinal airway pressure is plotted against tidal volume [54], which requires the insertion of an appropriate catheter.…”

Section: Work Of Breathingmentioning

confidence: 99%

Assessment of lung function in the ventilated patient

Macnaughton¹

1997

Intensive Care Med

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IntroductionThe ability to accurately assess lung function is essential in the management of patients requiring ventilation for acute respiratory failure. Such measurements aid in diagnosis, in optimising mechanical ventilatory support and in predicting the likelihood of success at weaning. Undertaking and interpreting these investigations in the critically ill poses significant challenges. Patients are often unable to undertake complex respiratory maneuvers. Further, normal values for many of the standard respiratory function tests are lacking, when applied in the postures and with the inspired oxygen concentrations (F I O 2 ) required by the critically ill. However, the presence of an endotracheal tube and the monitoring system incorporated into modern microprocessor controlled ventilators can significantly aid the clinician in undertaking certain investigations. Gas exchangeGas exchange is assessed by the intermittent analysis of arterial blood gas tensions. Continuous arterial gas tension monitoring is now available and utilizes miniaturized fibre-optic probes placed within the arterial cannula [1], although its clinical utility has not been assessed to date. Hypoxaemia may be caused by intra-pulmonary shunting or ventilation perfusion inhomogeneity [2]. A number of indices which are functions of FIO 2 have been described to quantify the severity of hypoxaemia including alveolar-arterial PO 2 difference (AaDO 2 ), arterial/alveolar ratio (PaO 2 /PAO 2 ) and PaO 2 : FIO 2 ratio. However, due to the non linear relationship between oxygen tension and content as demonstrated by the oxygen haemoglobin dissociation curve, all these indices are affected by changes in FIO 2 . The PaO 2 : FIO 2 ratio exhibits the most stability, particularly when used at FIO 2 above 50 % in patients with a shunt fraction in excess of 30 % [3]. Thus the PaO 2 : FIO 2 ratio is the most acceptable non-invasive index of pulmonary oxygenation in patients with lung injury and is used to differentiate acute lung injury ( > 200 mm Hg) from the acute respiratory distress syndrome ( < 200 mm Hg) [4]. Although it is the preferred method of assessing gas exchange in clinical trials carried out in patients with ARDS [5], the PaO 2 : FIO 2 ratio does not necessarily reflect the overall severity of lung injury and is not of prognostic value. Shunt fraction can be estimated from the relevant equation if samples of arterial and mixed venous blood (from a pulmonary artery catheter) are obtained [6]. However, measurements of intrapulmonary shunt may be less stable with changing FIO 2 than the PaO 2 : FIO 2 ratio and vary in proportion to the degree of V : Q inhomogeneity [3]. Shunt should be measured with an FIO 2 of 1.0, although this may increase shunt further due to diffusion atelectasis. Calculations of shunt performed at lower FIO 2 quantify the venous admixture and also reflect the shunt-like effect of V : Q inhomogeneity and diffusion limitation. Due to these limitations and the requirement for a pulmonary artery catheter, there appears to be no ...

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Imposed work of breathing and methods of triggering a demand-flow, continuous positive airway pressure system

Cited by 68 publications

References 0 publications

Angle Effect to Dropping of Dew in Closed Suction Catheters

Angle Effect to Dropping of Dew in Closed Suction Catheters

Contribution of the Endotracheal Tube and the Upper Airway to Breathing Workload

Assessment of lung function in the ventilated patient

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