The Effect of Varying Inspiratory: Expiratory Ratios on Gas Exchange During Anaesthesia for Open-Heart Surgery

Sykes, M.K.; Lumley, Jean

doi:10.1093/bja/41.5.374

Cited by 28 publications

(5 citation statements)

References 16 publications

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“…A reduction in physiological dead space when using a prolonged I : E ratio, has been widely reported before [3,7,9,12,15,16]. This occurred with IPPV-4:1 and to a lesser, but still highly significant extent (p < 0.01) with IRV-min.…”

Section: Discussionsupporting

confidence: 58%

Inverse ratio ventilation compared with PEEP in adult respiratory failure

1984

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We have compared the cardiorespiratory effects of an inspiratory: expiratory (I:E) ratio of 4:1 with a ratio of 1:2 in 10 adult patients requiring intermittent positive pressure ventilation (IPPV) for acute respiratory insufficiency. Further comparisons were made with IPPV with positive end-expiratory pressure (PEEP) which was adjusted to achieve an equal external end-expiratory volume (EEEV) to that produced by the 4:1 ratio, as determined by respiratory inductive plethysmography, and with an I:E ratio that only changed the EEEV minimally (IRV-min). Percentage pulmonary shunt (Qs/Qt) was reduced equally with PEEP and with the 4:1 I:E ratio but both patterns reduced cardiac output and oxygen delivery. IRV-min also reduced Qs/Qt significantly but had no effect on cardiac output so that oxygen delivery was increased. The dead space to tidal volume ratio (VD/VT) during IPPV-4:1 and IRV-min was reduced significantly when compared with that during IPPV-1:2. The clinical implications of the findings suggest that for some ITU patients, a modest increase in I:E ratio to between 1.1:1 and 1.7:1 may produce better gas exchange without significantly effecting the cardiac output.

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Section: Discussionsupporting

confidence: 58%

Inverse ratio ventilation compared with PEEP in adult respiratory failure

1984

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“…The use of mechanical ventilatory support following open heart surgery has become widespread (Grenvik, 1966;Gattiker, Hossli and Rothlin, 1970;Pontopiddan, Laver and Geffin, 1970;Laver, Hallo well and Goldblatt, 1970;Sykes et al, 1970) but it has been shown that cardiac output increases when patients who have undergone thoracic surgery are taken off intermittent positive pressure ventilation (Grenvik, 1966). In normal patients during anaesthesia, both the institution of mechanical ventilation while keeping Paco, constant and the lowering of Paooj during artificial ventilation cause reduction in cardiac output .…”

Section: Discussionmentioning

confidence: 99%

“…In normal patients during anaesthesia, both the institution of mechanical ventilation while keeping Paco, constant and the lowering of Paooj during artificial ventilation cause reduction in cardiac output . However, some patients who are in cardiac failure or who are critically ill may show an increase in cardiac output following the institution of IPPV (Werko, 1947;Clowes et al, 1965). In these cases the explanations suggested for the rise are reduction of filling pressure of an overloaded right ventricle or improved oxygenation and reduction of metabolic acidosis.…”

Section: Discussionmentioning

confidence: 99%

“…In these cases the explanations suggested for the rise are reduction of filling pressure of an overloaded right ventricle or improved oxygenation and reduction of metabolic acidosis. Some information is available about the use of different patterns of ventilation for patients after cardiopulmonary bypass procedures with regard to inspiratory: expiratory ratios (Sykes and Lumley, 1969) and the use of positive end-expiratory pressure (Seed, Sykes and Finlay, 1970), but no evidence is available on the optimum level for maintenance of Pac O= in these patients.…”

Section: Discussionmentioning

confidence: 99%

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The Effect of Carbon Dioxide on Cardiac Output in Patients Undergoing Mechanical Ventilation Following Open Heart Surgery

Hewitt

Chamberlain

Seed

1973

British Journal of Anaesthesia

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“…Under these modes a square wave of pressure is intermittently applied to the airway opening, and alveolar pressures and volumes are established during inspiration. Opinions differ as to whether improvements in gas exchange and lung mechanics can be specifically attributed to particular types of inspiratory flow pattern (1,3,5,28). In patients, the pathophysiology of acute respiratory failure is complex, having many causes and effects.…”

Section: Examples Of Newer Means Of Mechanical Ventilation Are Modifimentioning

confidence: 99%

Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension

Markström¹,

Hedlund

Lichtwarck-Aschoff³

et al. 2000

Upsala Journal of Medical Sciences

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Ventilation with decelerating inspiratory flow is known to reduce the dead space fraction and to decrease PaCO2 . Constant inspiratory flow with an end-inspiratory pause (EIP) is also known to increase the removal of CO,.The aim of the study was to elucidate the effect of the pauseho-flow period while both the pattern and rate of inspiratory flow was unchanged, and when the lung was ventilated with sufficient PEEP to prevent end-expiratory collapse.Surfactant depleted piglets were assigned to decelerating or constant inspiratory flow with 24 breaths per minute (bpm) or12 bpm, or to constant flow, without and with an end-inspiratory pause of 25%. By adding an EIP the total time without active inspiratory flow of the respiratory cycle was kept unchanged. Gas exchange, airway pressures, functional residual capacity (using sulfurhexafluoride) and haemodynamics (thermo-dye indicator dilution technique) were measured.Irrespective of ventilatory frequency, PaCOz was lower and serial dead space reduced with decelerating flow, compared with constant inspiratory flow. With an end-inspiratory pause added to constant inspiratory flow, serial dead space was reduced but did not decrease PaCO, .The results of this study corroborate the assumption that total time without active inspiratory flow is important for arterial C0,-tension.

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The Effect of Varying Inspiratory: Expiratory Ratios on Gas Exchange During Anaesthesia for Open-Heart Surgery

Cited by 28 publications

References 16 publications

Inverse ratio ventilation compared with PEEP in adult respiratory failure

Inverse ratio ventilation compared with PEEP in adult respiratory failure

The Effect of Carbon Dioxide on Cardiac Output in Patients Undergoing Mechanical Ventilation Following Open Heart Surgery

Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension

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The Effect of Varying Inspiratory: Expiratory Ratios on Gas Exchange During Anaesthesia for Open-Heart Surgery

Cited by 28 publications

References 16 publications

Inverse ratio ventilation compared with PEEP in adult respiratory failure

Inverse ratio ventilation compared with PEEP in adult respiratory failure

The Effect of Carbon Dioxide on Cardiac Output in Patients Undergoing Mechanical Ventilation Following Open Heart Surgery

Impact of Different Inspiratory Flow Patterns on Arterial CO2-tension

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Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension