Ventilator-delivered mask ventilation compared with three standard methods of mask ventilation in a manikin model.

BACKGROUND: Little is known regarding the variations in effective ventilation during bag and mask resuscitation with standard methods compared with that delivered by ventilator-delivered mask ventilation (VDMV). AIM: To measure the variations in delivered airway pressure, tidal volume (TV), minute ventilation (MV) and inspiratory time during a 3-min period of mask ventilation comparing VDMV with three commonly used hand-delivered methods of bag and mask ventilation: Laerdal self-inflating bag (SIB); anaesthetic bag and T-piece Neopuff. METHODS: A modified resuscitation manikin was used to measure variation in mechanical ventilation during 3-min periods of mask ventilation. Thirty-six experienced practitioners gave positive pressure mask ventilation targeting acceptable chest wall movement with a rate of 60 inflations/min and when pressures could be targeted or set, a peak inspiratory pressure (PIP) of 18 cm water, positive end-expiratory pressure (PEEP) of 5 cm water, for 3 min with each of the four mask ventilation methods. Each mode was randomly sequenced. RESULTS: A total of 21 136 inflations were recorded and analysed. VDMV achieved PIP and PEEP closest to that targeted and significantly lower variation in all measured parameters (p<0.001) other than with PIP. SIB delivered TV and MV over twice that delivered by VDMV and Neopuff. CONCLUSION: During 3-min periods of mask ventilation on a manikin, VDMV produced the least variation in delivered ventilation. SIB produced wide variation and unacceptably high TV and MV in experienced hands.

Mask leak in one-person mask ventilation compared to two-person in newborn infant manikin study.

AIM: To compare a new two-person method (four hands) of delivering mask ventilation with a standard one-person method using the Laerdal self-inflating bag (SIB) and the Neopuff (NP) infant resuscitator in a manikin model. BACKGROUND: Recent studies of simulated neonatal resuscitation using bag and mask ventilation techniques have shown facemask leak levels of 55-57% in expert hands. METHODS: 48 participants were randomly paired and instructed to give mask ventilation for a 2-min period as single-person resuscitators, then as two-person paired resuscitators at set pressures for NP and set parameters for SIB. Airway pressure, flow, inspiratory tidal volume, expiratory tidal volume and mask leak were recorded. RESULTS: A total of 21 578 inflations were recorded and analysed. For SIB, mask leak was greater (11.5%) with single-person compared to two-person (5.4%; mean difference 6.1%, 95% CI 1.5 to 10.7, p<0.01). For NP, mask leak was greater for single-person (22.2%) compared to two-person (9.1%; mean difference 13.1% 95% CI 3.6 to 22.6, p<0.01). For single-person mask ventilation, mask leak was greater with NP (22.2%) compared to SIB (11.5%; mean difference 10.7%, 95% CI 1.4 to 19.7, p<0.01). For two-person mask ventilation, mask leak was greater for NP (9.1%) compared to SIB (5.4%; mean difference 3.7%, 95% CI 0.1 to 6.4, p<0.05). CONCLUSIONS: Two-person mask ventilation technique reduces mask leak by approximately 50% compared to the standard one-person mask ventilation method. NP mask ventilation has higher mask leak than Laerdal SIB for both single- and two-person technique mask ventilation.

Home birth and the National Australian Maternity Services Review: too hot to handle?

BACKGROUND: In February 2009 the Improving Maternity Services in Australia - The Report of the Maternity Services Review (MSR) was released, with the personal stories of women making up 407 of the more than 900 submissions received. A significant proportion (53%) of the women were said to have had personal experience with homebirth. Little information is provided on what was said about homebirth in these submissions and the decision by the MSR not to include homebirth in the funding and insurance reforms being proposed is at odds with the apparent demand for this option of care. METHOD: Data for this study comprised 832 submissions to the MSR that are publicly available on the Commonwealth of Australia Department of Health and Aging website. All 832 submissions were downloaded, coded and then entered into NVivo. Content analysis was used to analyse the data that related to homebirth. FINDINGS: 450 of the submissions were from consumers of maternity services (54%). Four hundred and seventy (60%) of the submissions mentioned homebirth. Overall there were 715 references to home birth in the submissions. The submissions mentioning homebirth most commonly discussed the 'Benefits' and 'Barriers' in accessing this option of care. Benefits to the baby, mother and family were described, along with the benefits obtained from having a midwife at the birth, receiving continuity of care and having a good birth experience. Barriers were described as not having access to a midwife, no funding, no insurance and lack of clinical privileging for midwives. CONCLUSION: Many positive recommendations have come from the MSR, however the decision to exclude homebirth from these reforms is perplexing considering the large number of submissions describing the benefits of and barriers to homebirth in Australia. A concerning number of submissions discuss having had or having considered an unattended birth at home due to these barriers. Overall there is the belief that not enabling access to funded, insured homebirth in Australia is a violation of human rights. It appears that homebirth was considered by the MSR as 'too hot to handle' and by dismissing it as a minority issue the government sought to avoided dealing with homebirth as a 'sensitive and controversial issue.'

Neopuff T-piece mask resuscitator: is mask leak related to watching the pressure dial?

AIM: The aim of the study is to compare mask leak and delivered ventilation during Neopuff (NP) mask ventilation in two modes: (i) with NP pressure dial hidden and resuscitator watching chest wall (CW) rise with, (ii) CW movement hidden and resuscitator watching NP pressure dial. METHODS: Thirty-six participants gave mask ventilation to a modified manikin designed to measure mask leak and delivered ventilation for two minutes in each mode randomly assigned. Paired t-tests were used to analyse differences in mean values. Linear regression was used to determine the association of mask leak with delivered ventilation. RESULTS: Of 7277 inflations analysed, 3621 were observing chest wall mode (CWM) and 3656 observing NP mode (NPM). Mask leak was similar between the groups; 31.6% for CWM and 31.5% (p = 0.56) for NPM. There were no significant differences in airways pressures and expired tidal volumes (TVe) between modes. Mask leak was strongly associated with TVe (R = -0.86 p < 0.0001) and with peak inspiratory pressure (PIP) (R = -0.51 p < 0.0001). TVe was associated with PIP (R = 0.51 p < 0.0001). CONCLUSION: This study provides reassurance that NP mask leak is not greater when resuscitators watch the NP pressure dial. Mask leak is related to TVe. Mask ventilation training with manikins should include tidal volume measurements.

Does caffeine impair cerebral oxygenation and blood flow velocity in preterm infants?

AIM: The aim of the study is to assess the effects of an intravenous 10 mg/kg loading dose of caffeine base in cerebral oxygenation, cerebral Doppler blood flow velocity and cardiac output in preterm infants. METHODS: Preterm neonates <34 weeks gestation were investigated at 1 and 4 h following the loading dose of caffeine using Doppler cerebral sonography, cardiac echocardiography and cerebral spatially resolved near-infrared spectroscopy. RESULTS: Forty infants were studied with a mean gestational age (mean ± standard deviation) of 27.7 (±2.5) weeks, birth weight of 1155 (±431) g and a postnatal age of 2.8 (±2.2) days. Mean Anterior Cerebral Artery peak and time average mean blood flow velocity fell significantly by 14% and 17.7%, respectively at 1 h post-caffeine loading dose, which recovered partially by 4 h. Cerebral Tissue Oxygenation Index fell from pre-dose levels by 9.5% at 1 h with partial recovery to 4.9% reduced at 4 h post-dose. There were no significant changes in left or right ventricular output, transcutaneous oxygen saturation, transcutaneous PCO(2) or total vascular resistance. CONCLUSIONS: A loading dose of 10 mg/kg caffeine base resulted in significant reduction at 1 h post-dose in cerebral oxygenation and cerebral blood flow velocity with partial recovery at 4 h.

Spontaneous preterm birth of liveborn infants in women at low risk in Australia over 10 years: a population-based study.

OBJECTIVES: To describe a 10-year trend in preterm birth. DESIGN: Population-based study. SETTING: Australia. POPULATION: All women who gave birth during 1994-03. METHODS: The proportion of spontaneous preterm births (greater than or equal to 22 weeks of gestation and less than 37 completed weeks of gestation) was calculated by dividing the number of women who had a live spontaneous preterm birth (excluding elective caesarean section and induction of labour) by the total number of women who had a live birth after spontaneous onset of labour (excluding elective caesarean section and induction of labour). This method was repeated for the selected population of women at low risk. MAIN OUTCOME MEASURE: Preterm birth rates among the overall population of women; preterm birth among all women with a spontaneous onset of labour; and preterm birth in a selected population of women who were either primiparous or multiparous, non-Indigenous; aged 20-40 years and who gave birth to a live singleton baby after the spontaneous onset of labour. RESULTS: Over the 10-year study period, the proportion of all women having a live preterm birth in Australia increased by 12.1% (from 5.9% in 1994 to 6.6% in 2003). Among women with a spontaneous onset of labour, there was an increase of 18.3% (from 5.7 to 6.7%). Among the selected population of low-risk women after the spontaneous onset of labour, the rate increased by 10.7% (from 5.6 to 6.2%) among first time mothers and by 19.2% (4.4-5.2%) among selected multiparous women. CONCLUSIONS: Over the 10-year period of 1994-03, the rate of spontaneous preterm birth among low-risk women having a live singleton birth has risen in Australia.