Cardiorespiratory effects of an inspiratory hold and continuous positive pressure ventilation in goats

Perez-Chada, R. D.; Gardaz, J. P.; Madgwick, R.; Sykes, M.K.

doi:10.1007/bf01691252

Cited by 16 publications

(6 citation statements)

References 26 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%

“…In the present studies mean airway pressure was significantly higher during IPPV-4:1 than during PEEP with the same EEEV. In previous work on animals [3,12] the mean airway pressures instead of FRC were used to match PEEP with IRV. This would have produced a higher FRC during PEEP and might have explained the greater improvement in Qs/Qt with PEEP which was observed.…”

Section: Discussionmentioning

confidence: 99%

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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%

Section: Discussionmentioning

confidence: 99%

Inverse ratio ventilation compared with PEEP in adult respiratory failure

1984

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“…Anaesthesia was induced in 17 dogs of either sex and mixed breed (weight 19.7 + 5.0 kg) using sodium thiopentone 20-25 mg kg" 1 i.v., following premedication with morphine sulphate 1.5-2.0 mg kg" 1 . Anaesthesia was maintained with 1.5% halothane for the duration of surgery and, thereafter, with 0.5 % halothane in oxygen to the right lung and an i.v.…”

Section: Methodsmentioning

confidence: 99%

“…Severe arterial hypoxaemia resulting from acute lung disease is frequently treated with positive end-expiratory pressure (PEEP) or an increase in inspiratory: expiratory (I:E) time ratio, the latter being produced either by a reduction in inspiratory flow rate or by the addition of an inspiratory pressure plateau. The reduction in shunt associated with PEEP or an increase in I:E ratio is probably a result of the recruitment of previously collapsed alveoli secondary to an increase in end-expiratory lung volume [1]. However, the improved oxygenation appears to be related most closely to the increase in mean airway pressure [2], and there is evidence that the addition of an inspiratory pressure plateau can decrease shunt even though end-expiratory volume is little changed [3].…”

mentioning

confidence: 99%

Effects of the Pattern of Ventilation and of an Increase in Cardiac Output on the Distribution of Blood Flow to a Hypoxic Lung Lobe

Cannon

Kalso

Sykes

1988

British Journal of Anaesthesia

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Electromagnetic flow probes were used to measure the fraction of the pulmonary blood flow perfusing the left lower lobe (Ql/Qt) in 16 anaesthetized, open-chest dogs in order to study the effects of right lung airway pressure on the distribution of blood flow to a hypoxic lung lobe. Ventilation of the lobe with 7% oxygen in nitrogen resulted in a 37% reduction in Ql/Qt at the beginning and end of the main procedure, thus confirming that the hypoxic pulmonary vasoconstrictor response was unchanged throughout the study. The effects of varying mean airway pressure to the right lung by changing inspiratory:expiratory time ratio and by the addition of a positive end-expiratory pressure were studied when the left lower lobe was insufflated with oxygen or 7% oxygen in nitrogen, or was collapsed. Insufflation of the lobe with 7% oxygen in nitrogen and collapse reduced Ql/Qt by 61% and 66%, respectively. However, changing mean airway pressure in the right lung produced no significant changes in Ql/Qt in any of the different lobar conditions or when collapse was produced after fluid loading. Fluid loading during collapse increased cardiac output and pulmonary vascular pressures and increased Ql/Qt to a value which was not significantly different from lobar ventilation with 7% oxygen in nitrogen. It is concluded that moderate increases in mean airway pressure do not increase Ql/Qt when this has been reduced by exposure of the lobe to mixed venous blood-gas tensions.

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“…Although the degree of dilution is reduced by the fact that carbon dioxide continues to flow into the alveolus during inspiration, it is known that changes in the pattern of breathing can influence the carbon dioxide concentration in the alveolus and so influence the elimination of the carbon dioxide. For example, increasing the I: E ratio during mechanical ventilation decreases (Paco, -PE' COI ) an d increases the efficiency of carbon dioxide elimination (Perez-Chada et al, 1983) whereas in exercise, when carbon dioxide production is very high, (Paco^^'cot) mav become negative (Jones, Robertson and Kane, 1979). High frequency jet ventilation results in a marked decrease in alveolar tidal volume so that the inspiratory dilution of alveolar gas is minimized, and it is possible that this may reduce (Pa COt -PE'CO,) to values observed during the first breath.…”

Section: Discussionmentioning

confidence: 99%

Estimation of Arterial P Co 2 During High Frequency Jet Ventilation

Mortimer¹,

Cannon²,

Sykes³

1987

British Journal of Anaesthesia

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The arterial to end-tidal PCO2 difference (PaCO2-PE'CO2) was measured in five anaesthetized dogs during controlled ventilation at 0.25 Hz (15 b.p.m.) and during high frequency jet ventilation at 1, 3 and 5 Hz. Because of the slow response of the infra-red carbon dioxide analyser, satisfactory recordings of end-tidal carbon dioxide could not be obtained at frequencies greater than 1 Hz. The interruption of high frequency jet ventilation by conventional ventilation resulted in approximately equal arterial and end-tidal PCO2 values during the first breath, and restoration of the normal arterial to end-tidal PCO2 difference by the third breath. It is concluded that, when high frequency jet ventilation at 1, 3 or 5 Hz is interrupted with normal tidal volumes at low frequencies, the arterial PCO2 can be estimated from recordings of the end-tidal PCO2.

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Cardiorespiratory effects of an inspiratory hold and continuous positive pressure ventilation in goats

Cited by 16 publications

References 26 publications

Inverse ratio ventilation compared with PEEP in adult respiratory failure

Inverse ratio ventilation compared with PEEP in adult respiratory failure

Effects of the Pattern of Ventilation and of an Increase in Cardiac Output on the Distribution of Blood Flow to a Hypoxic Lung Lobe

Estimation of Arterial P Co 2 During High Frequency Jet Ventilation

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