Effects of induction of anaesthesia and muscle paralysis on functional residual capacity of the lungs

Laws, Ami

doi:10.1007/bf03006957

Cited by 110 publications

(22 citation statements)

References 17 publications

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“…Induction of general anaesthesia causes a rapid decrease in functional residual capacity (FRC) [1], which may promote alveolar collapse and airway closure in dependent lung regions [2]. Mismatching of ventilation and perfusion in the lungs is accompanied by impairment of pulmonary gas exchange [3,4].…”

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confidence: 99%

Lung aeration and pulmonary gas exchange during lumbar epidural anaesthesia and in the lithotomy position in elderly patients

et al. 1998

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SummaryWe investigated a total of 36 subjects with a mean (SD) age of 65 (13) years, during baseline conditions (supine, before any anaesthesia), and then during one of the following protocols: (1) lithotomy positioning (n ¼ 12), (2) epidural anaesthesia (n ¼ 12), (3) general anaesthesia in the supine position (n ¼ 12). Lung aeration, ventilation/perfusion matching, gas exchange and functional residual capacity were measured. Lung aeration was normal during baseline assessment with almost no regions with poor aeration and no substantial dependent densities. Shunt and perfusion of poorly ventilated regions were minor. Lithotomy positioning did not reduce functional residual capacity and did not affect aeration of the lung or ventilation/perfusion matching. Epidural anaesthesia, in general, had no effect on aeration, ventilation/perfusion matching or gas exchange, regardless of whether the patient was in the supine or lithotomy position. General anaesthesia, however, caused significant increases in poorly aerated lung regions and in dependent densities (interpreted as atelectasis). In conclusion, no or little impairment of lung aeration and ventilation/perfusion matching was caused by the lithotomy position and/or epidural anaesthesia, contrary to the effects seen during general anaesthesia. However, our findings also suggest that being overweight is a factor that may cause impairment of lung aeration.

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confidence: 99%

Lung aeration and pulmonary gas exchange during lumbar epidural anaesthesia and in the lithotomy position in elderly patients

et al. 1998

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“…Although there was clearly no gross change of lung volume after the induction of anaesthesia (Fig. 2), the technique employed was not suitable for the detection of small changes in functional residual capacity which have been reported by DCry et al (1965) and Laws (1968). In no patient did the lung volume, at scan, change by more than 7% and the mean change was less than 1 %.…”

Section: Discussionmentioning

confidence: 57%

Influence of Anaesthesia on the Regional Distribution of Perfusion and Ventilation in the Lung

Hulands¹,

Greene²,

Iliff³

et al. 1970

Clinical Science

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1. Distribution of lung volume, pulmonary ventilation and perfusion were studied in supine patients before and during anaesthesia with paralysis and artificial ventilation. Inspired gas and pulmonary blood flow were measured with 33xenon and the chest was scanned with vertically moving counters at a lung volume of 1 litre above functional residual capacity.2. Ventilationlunit lung volume was slightly greater and perfusionlunit lung volume substantially greater during anaesthesia in the dependent parts of the lungs. The spread of ventilation/perfusion ratios in supine conscious patients was small in comparison with that reported in upright conscious patients. During anaesthesia and artificial ventilation, the inequality of ventilation to perfusion was marginally increased in three of the four patients.3. Ventilationlperfusion inequality alone was insufficient to explain the alveolararterial Po, difference usually observed during anaesthesia.In the conscious patient the alveolar and arterial Po, normally differ by only a few torr. A substantial increase has been consistently found to follow the induction of anaesthesia and the normal difference is not regained until some hours after the end of anaesthesia and surgery (Nunn & Payne, 1962;Nunn, Bergman & Coleman, 1965). The change remains unexplained. Although there is usually some increase in the measured venous admixture, it is uncertain to what extent this might be explained by an increase in the normal gravitational spread of ventilationlperfusion (P/Q) ratios found in the conscious patient (west, 1965); we are not aware of any previous reports of measurement of the regional distribution of ventilation and pulmonary blood flow during anaesthesia. In this study, we have measured the effect of anaesthesia with paralysis and artificial ventilation on the distribution of ventilation and pulmonary blood flow using 133xenon, modified from the method of Ball et al. (1962).

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“…These changes in breathing mechanics have not been sufficiently explained. However, the functional residual capacity (FRC) is reduced with controlled ventilation (13, 26), and this reduction might explain the lowered compliance in terms of airway closure and the increased resistance in A further explanation of the reduction in lung compliance may be a slowed stress-relaxation (41), a possible consequence of changes in the surfactant. It must also be pointed out that the increase in resistance may be due to an increased tissue resistance (perhaps the surfactant) and not necessarily to changes in airway resistance.…”

Section: Discussionmentioning

confidence: 98%

Acute Effects of Intermittent Positive Pressure Breathing in Patients with Chronic Obstructive Lung Disease

Hedenstierna¹,

Gertz²

1976

Scandinavian Journal of Clinical and Laboratory Investigation

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The immediate effects of intermittent positive pressure breathing (IPPB) on air were studied in seven patients (age 55-73 years) with advanced chronic obstructive lung disease (COLD) and with chronic respiratory insufficiency. Dynamic lung compliance was reduced by an average of 25% by IPPB, while inspiratory resistance increased by 40%. Distribution of inspired gas, as determined by nitrogen washout, became more even with IPPB. Respiratory frequency was not altered, whereas total ventilation increased by 25% during IPPB and PaCO2 was reduced. Oxygen uptake was reduced by 6%. PaO2 did not change during IPPB but had decreased by an average of 20% 10 minutes after IPPB and then slowly improved; PaCO2 did not change after IPPB. The pressures in the right atrium, pulmonary artery, and in pulmonary wedge position all increased approximately 2 mm Hg (approximately 2 cm H2O) with IPPB, while intrathoracic pressure rose on an average by 5 cm H2O, the transmural pressures thus being lowered during IPPB. The pulmonary vascular resistance was not significantly altered by IPPB, whereas the systemic vascular resistance rose 25%. Cardiac output was reduced approximately 20% and venous admixture almost 50%.

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Effects of induction of anaesthesia and muscle paralysis on functional residual capacity of the lungs

Cited by 110 publications

References 17 publications

Lung aeration and pulmonary gas exchange during lumbar epidural anaesthesia and in the lithotomy position in elderly patients

Lung aeration and pulmonary gas exchange during lumbar epidural anaesthesia and in the lithotomy position in elderly patients

Influence of Anaesthesia on the Regional Distribution of Perfusion and Ventilation in the Lung

Acute Effects of Intermittent Positive Pressure Breathing in Patients with Chronic Obstructive Lung Disease

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