A New Method of Spirometry Applicable to Routine Anaesthesia

Nunn, J. F.

doi:10.1093/bja/28.10.440

Cited by 22 publications

(9 citation statements)

References 4 publications

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“…When breathing air with a sinusoidal waveform, the respirometer would normally read 10 per cent low, at a minute volume of about 3.4 1. Minute volumes of this order are certainly encountered in routine anaesthesia (Nunn, 1958), but two factors-waveform and the nature of the respired gas-combine to minimize, if not prevent, the error which might be expected.…”

Section: Discussionmentioning

confidence: 99%

“…The relationship between waveform and low minute volumes was studied in 44 fast spirometer traces recorded during a previous study of spontaneous respiration under anaesthesia (Nunn, 1958). The spirograms were divided into three groups:…”

Section: Discussionmentioning

confidence: 99%

“…Considerable experience was gained in the use of the respirometer and ventigrator under conditions of routine surgery. Direct comparison was made between the ventilation measured with the respirometer and with a continuous flow spirometer incorporated in a circle system (Nunn, 1956). The respirometer was reversed to measure both inspiratory and expiratory minute volumes.…”

Section: Studies In Anaesthetized Patientsmentioning

confidence: 99%

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The Accuracy of the Respirometer and Ventigrator

Nunn

Ezi-Ashi

1962

British Journal of Anaesthesia

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The respirometer under-reads at low flow rates and over-reads at high flow rates, but during anaesthesia, the respiratory waveform and the nature of the respired gas combine' to minimize the low error which would otherwise result from hypoventilation. Over-reading is to be expected during hyperventilation of the anaesthetized patient. The error will always exaggerate a departure from normality. The response of the ventigrator is proportional to the square of the gas flow rate. Consequently the sensitivity is poor at low flow rates and excessive at high flow rates and, furthermore, the signal is markedly influenced by the peak flow/minute volume ratio. The response of the ventigrator is directly proportional to the vapour density of the respired gases. Large corrections are, therefore, required during anaesthesia.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Studies In Anaesthetized Patientsmentioning

confidence: 99%

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The Accuracy of the Respirometer and Ventigrator

Nunn

Ezi-Ashi

1962

British Journal of Anaesthesia

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“…The valve-less, non-rebreathing technique used to measure ventilation during the air breathing experiments was adapted from that described by Nunn (1956) and has been previously described by us (Bechbache, Chow, Duffin & Orsini, 1979). The volunteers breathed at rest, while standing on the treadmill, for 5 min and then the treadmill was started without warning and the exercise was continued for 4 min thereafter.…”

Section: Exercise Ventilation and Treadmill Speedmentioning

confidence: 99%

The effect of treadmill speed on ventilation at the start of exercise in man.

Casey

Duffin

Kelsey

et al. 1987

The Journal of Physiology

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SUMMARY1. The change in ventilation at the start of exercise was determined during both hyperoxic rebreathing and air breathing in four volunteers.2. In order to differentiate between the effects of limb-movement frequency and exercise load in terms of oxygen uptake, three treadmill exercises were tested: El, at an oxygen uptake of 1 1/min on a level treadmill; E2, at 2 1/min on an inclined treadmill at the same speed as El; E3, at 2 1/min on a level treadmill at a higher speed. All of the exercises were performed at a walking pace. 3. Prior to rebreathing, hyperventilation for 5 min to 20 mmHg was used to reduce carbon dioxide to below the central chemoreceptor threshold. From eleven to fourteen rebreathing experiments were done on each volunteer for each of the three exercises, with the treadmill started at carbon dioxide levels which ranged from 36 (below threshold) to 58 mmHg (above threshold).4. Ten experiments were performed on each volunteer for each of the three exercises during air breathing, with the treadmill started after 5 min of rest.5. In both the rebreathing experiments and the air breathing experiments it was found that the change in ventilation at the start of exercise was the same for exercises El and E2, and significantly greater for exercise E3.6. It was concluded that the frequency of limb movement, rather than exercise load (oxygen consumption) is a determinant of the change in ventilation at the start of exercise.

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“…The steady-state method used in these studies was that described by Nunn (1956). The volunteers breathed through a wide-bore (3-8 cm) T piece with negligible dead-space.…”

Section: Apparatusmentioning

confidence: 99%

The effects of hypercapnia, hypoxia, exercise and anxiety on the pattern of breathing in man.

Bechbache¹,

Chow²,

Duffin³

et al. 1979

The Journal of Physiology

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SUMMARY1. The pattern of breathing, defined as the relations between tidal volume and inspiratory and expiratory times, was measured during the stimulation of breathing by carbon dioxide (hyperoxic rebreathing at rest) in twenty-seven healthy, young volunteers.2. Most of the patterns (twenty) were divisible into two parts, for low (range 1) and high (range 2) tidal volumes. The relations were curved, inverse proportionalities for both inspiration and expiration in range 2, and for expiration in range 1. The relations for inspiration in range 1 were evenly divided between those with constant inspiratory times (type 1) and those with curved, inverse proportionalities (type 2).3. In four volunteers, direct proportionalities predominated and the patterns were scattered (type 3).4. Eight of the volunteers (four type 1, two type 2 and two type 3 patterns) repeated the measurements and one changed from a type 1 to a type 3 pattern.5. Nine of the volunteers also rebreathed during resting hypoxia. Two altered their patterns, and the others had patterns which were superimposed upon those measured during hyperoxic rebreathing at rest.6. Eighteen of the volunteers also rebreathed (hyperoxic) during light exercise (25 W). Five entrained their breathing frequency to the exercise rhythm and showed exercise patterns with constant inspiratory and expiratory times. The others had patterns which were extensions of those measured during hyperoxic rebreathing at rest.7. The pattern of breathing in range 1 was measured by steady-state methods in a further ten volunteers at rest with their eyes closed and open, and during mental arithmetic. The pooled average pattern showed that the stress of mental arithmetic shortened both inspiratory and expiratory times, and changed a type 2 pattern into a type 1 pattern.

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A New Method of Spirometry Applicable to Routine Anaesthesia

Cited by 22 publications

References 4 publications

The Accuracy of the Respirometer and Ventigrator

The Accuracy of the Respirometer and Ventigrator

The effect of treadmill speed on ventilation at the start of exercise in man.

The effects of hypercapnia, hypoxia, exercise and anxiety on the pattern of breathing in man.

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