The effect of instrumental dead space on measurement of breathing pattern and pulmonary mechanics in the newborn

Marsh, Michael P.; Ingram, D.; Milner, Anthony

doi:10.1002/ppul.1950160508

Cited by 34 publications

(18 citation statements)

References 19 publications

(1 reference statement)

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“…Previous studies reported no adverse effects of a face mask during the first breaths (7)(8)(9)(10)(11)(12)(13)(14). It is possible that the added dead space of the face mask caused carbon dioxide accumulation and influenced the breathing pattern (46,47). However, the wide diameter of the mask reduced rebreathing and firm application of the mask reduced the dead space (15).…”

Section: Discussionmentioning

confidence: 99%

Spontaneous Breathing Patterns of Very Preterm Infants Treated With Continuous Positive Airway Pressure at Birth

et al. 2008

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There are no data describing how very preterm infants breathe spontaneously immediately after birth. We studied a convenience sample of spontaneously breathing infants Յ32 wk' gestation treated with facemask continuous positive airway pressure at birth. Airway pressure and flow were measured and each breath analyzed. Twelve infants had 792 breaths suitable for analysis. Results are given as mean (SD). Gestational age and birth weight were 29 (1.9) wk and 1220 (412) g. Recordings were started 159 (77) s after birth. The inspiratory pattern and duration was similar in all breaths at 0.36 (0.11) s. There were five expiratory patterns; most infants had more than one. In 79% of breaths expiratory duration (1.6 (1.1) s) was slowed or held by interruption or braking of expiratory flow. It was braked in 47% to a complete expiratory hold, in 22% by grunting or crying, and in 10% by slow or interrupted expiration. In 21% of the breaths, expiration was not interrupted and lasted 0.53 (0.13) s. Half of these breaths represented a panting pattern (rate Ͼ60 /min). Immediately after birth, most very preterm infants, treated with continuous positive airway pressure, frequently prolong their expiration by braking the expiratory flow. (Pediatr Res 64: 281-285, 2008)

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Section: Discussionmentioning

confidence: 99%

Spontaneous Breathing Patterns of Very Preterm Infants Treated With Continuous Positive Airway Pressure at Birth

et al. 2008

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“…However, unavoidable physiological dead space (VD,phys) and dynamic apparatus dead space (VD,ap) comprising alveolar gases that are inhaled a second time into the alveolar compartment, encroach on alveolar ventilation. This influences pulmonary mechanics and breathing pattern [1][2][3][4]. Flow through face masks appears to have significant impact upon dynamic dead space (VD) [5].…”

mentioning

confidence: 99%

“…Although determination of VD,phys is well studied in the literature, there are no studies that measure VD,ap in NIV. However, the use of face masks has the potential to influence VD,ap [1]. In this study, VD,ap is defined as the VD that exceeds VD,phys.…”

mentioning

confidence: 99%

Dynamic dead space in face masks used with noninvasive ventilators: a lung model study

Saatçı¹,

Miller²,

Stell³

et al. 2003

Eur Respir J

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The aim of this study was to determine what the influence of different designs of face masks and different noninvasive ventilator modes would be upon total dynamic dead space.Using a spontaneous breathing model, total dynamic dead space was measured when using 19 commercially available face masks and a range of ventilators in various ventilation modes.Total dynamic dead space during spontaneous ventilation was increased above physiological dead space from 32% to 42% of tidal volume by using face masks. The use of noninvasive ventilation modes such as bilevel and continuous positive airway pressure, with continuous pressure throughout the expiratory phase, reduced total dynamic dead space to approach physiological dead space with most face masks. Pressure assist and pressure support ventilation decreased total dynamic dead space to a lesser degree, from 42% to 39% of tidal volume. Face masks with expiratory ports over the nasal bridge resulted in beneficial flow characteristics within the face mask and nasal cavity, so as to decrease total dynamic dead space to less than physiological dead space from 42% to 28.5% of tidal volume.Exhaust ports over the nasal bridge in face masks effect important decreases in dynamic dead space provided positive pressure throughout the expiratory phase is used.

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“…Unfortunately, while being very simple, this measurement technique in¯uences the very parameters it is designed to measure, respiration being stimulated by irritation of the nucleus trigeminus during facial attachment of the mask [6,7], the additional resistance of the pneumotachometer (RPNT) and, most importantly, the apparatus dead space (VD,app) [8]. The latter is of particular concern in newborns due to their low absolute tidal volumes (5±8 mL .…”

mentioning

confidence: 99%

Effect of apparatus dead space on breathing parameters in newborns: “flow-through”versusconventional techniques

et al. 2001

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Commercial devices for tidal breathing measurements in newborns allow only short-term measurements, due to the high apparatus dead space of the face mask and pneumotachometer. The¯ow-through technique (FTT) minimizes the dead space by a background¯ow, thereby allowing long-term measurements. The aim of this study was to investigate the comparability of tidal breathing parameters using both techniques.Paired measurements of tidal breathing were performed in 86 sleeping infants (median (range) body weight 2.8 kg (1.9±5.3 kg), age 65 days (3±150 days)), using the FTT and SensorMedics 2600 (SM 2600).There was a signi®cant bias (pv0.001) in all tidal breathing parameters. Compared with the FTT, increases (95% con®dence interval (CI)) in tidal volume (VT), respiratory frequency (fR), and minute ventilation (V'E) were 0.74 (0.5±1.0) mL . kg -1 , 9.0 (6.9±11.2) . min -1 and 92 (74±109) mL . min -1 . kg -1 when measured with the SM 2600, representing average increases of 13, 17 and 30%, respectively, in response to the added dead space. By contrast, time to peak tidal expiratory¯ow as a proportion of expiratory time (tPTEF/tE) was changed by -0.09 (-0.11±-0.08). The mean (95% CI) change in tPTEF/tE of -54 (-62±-45)%, when measured in infants by the SM 2600, was remarkably similar to that observed during in vitro validation studies (-59 (-73±-44)%), suggesting that the discrepancies in timing parameters may be largely attributable to differences in signal processing.In conclusion, differences in measurement technique and precision of the devices used can result in signi®cant differences in tidal breathing parameters. This may impede the comparison of results within and between infants and the clinical interpretation of tidal breathing measurements in newborns. Eur Respir J 2001; 17: 108±114.

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The effect of instrumental dead space on measurement of breathing pattern and pulmonary mechanics in the newborn

Cited by 34 publications

References 19 publications

Spontaneous Breathing Patterns of Very Preterm Infants Treated With Continuous Positive Airway Pressure at Birth

Spontaneous Breathing Patterns of Very Preterm Infants Treated With Continuous Positive Airway Pressure at Birth

Dynamic dead space in face masks used with noninvasive ventilators: a lung model study

Effect of apparatus dead space on breathing parameters in newborns: “flow-through”versusconventional techniques

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