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Davies IM, Crossley KJ, McGillick EV, Nitsos I, Rodgers K, Thiel A, Zahra VA, Badurdeen S, te Pas AB, Hooper SB. Adverse respiratory patterns in near-term spontaneously breathing newborn lambs with elevated airway liquid volumes at birth. Front Pediatr 2024; 12:1336154. [PMID: 38690521 PMCID: PMC11058214 DOI: 10.3389/fped.2024.1336154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
Introduction Recent evidence indicates that respiratory distress (RD) in near-term infants is caused by elevated airway liquid (EL) volume at the beginning of air-breathing after birth. While the adverse effects EL volumes on newborn lung function are known, the effects on respiratory control and breathing patterns shortly after birth (<4 h) are unknown. We investigated the effects of EL volumes on cardiorespiratory function and breathing patterns in spontaneously breathing near-term newborn lambs in the first hours after birth. Methods At 137-8 days gestation (2-3 days prior to delivery; term ∼147 days), sterile surgery was performed on fetal sheep (n = 17) to implant catheters and blood flow probes. At 140 days, lambs were delivered via caesarean section under spinal anaesthesia. Airway liquid volumes were adjusted to mimic the level expected following vaginal delivery (∼10 ml/kg; Controls; n = 7), or elective caesarean section (∼30 ml/kg; elevated airway liquid group; EL; n = 10). Spontaneous breathing and cardiorespiratory parameters were recorded over four hours after birth. Non-invasive respiratory support with supplemental oxygen was provided if required. Results EL lambs required higher inspired oxygen levels (p = 0.0002), were less active (p = 0.026), fed less (p = 0.008) and had higher respiratory morbidity scores than Controls (p < 0.0001). EL lambs also displayed higher rates of breathing patterns associated with RD, such as expiratory braking and tachypnoea. These patterns were particularly evident in male EL lambs who displayed higher levels of severe respiratory morbidity (e.g., expiratory braking) than female EL lambs. Conclusion The study demonstrates that EL volumes at birth trigger respiratory behaviour and breathing patterns that resemble clinically recognised features of RD in term infants.
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Affiliation(s)
- I. M. Davies
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - K. J. Crossley
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - E. V. McGillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - I. Nitsos
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - K. Rodgers
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - A. Thiel
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - V. A. Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - S. Badurdeen
- Department of Paediatrics, Mercy Hospital for Women, Heidelberg, VIC, Australia
- Neonatal Research, Murdoch Children’s Research Institute, Melbourne, VIC, Australia
| | - A. B. te Pas
- Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
| | - S. B. Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
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Davies IM, Crossley KJ, McGillick EV, Nitsos I, Rodgers K, Thiel A, Zahra VA, te Pas AB, Hooper SB. Respiratory patterns in spontaneously breathing near-term lambs delivered by caesarean section under spinal anaesthesia. Front Pediatr 2023; 11:1273136. [PMID: 37876521 PMCID: PMC10590898 DOI: 10.3389/fped.2023.1273136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 08/31/2023] [Indexed: 10/26/2023] Open
Abstract
Introduction The transition to newborn life has typically been studied in intubated and mechanically ventilated newborn lambs delivered via caesarean section (CS) under general anaesthesia. As a result, little is known of the spontaneous breathing patterns in lambs at birth, particularly those at risk of developing respiratory distress (RD). We have developed a method for delivering spontaneously breathing near-term lambs to characterise their breathing patterns in the immediate newborn period. Methods At 137-8 days gestation (2-3 days prior to delivery; term ∼147 days), fetal lambs (n = 7) were partially exteriorised for instrumentation (insertion of catheters and flow probes) before they were returned to the uterus. At 140 days, lambs were delivered via CS under light maternal sedation and spinal anaesthesia. Lambs were physically stimulated and when continuous breathing was established, the umbilical cord was clamped. Breathing patterns were assessed by measuring intrapleural and upper-tracheal pressures during the first four hours after birth. Results Newborn lambs display significant heterogeneity in respiratory patterns in the immediate newborn period that change with time after birth. Seven distinct breathing patterns were identified including: (i) quiet (tidal) breathing, (ii) breathing during active periods, (iii) breathing during oral feeding, (iv) tachypnoea, (v) expiratory braking manoeuvres, (vi) expiratory pauses or holding, and (vii) step changes in ventilation. Conclusions We have described normal respiratory behaviour in newborn lambs, in order to identify respiratory behaviours that are indicative of RD in term newborn infants.
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Affiliation(s)
- I. M. Davies
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - K. J. Crossley
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - E. V. McGillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - I. Nitsos
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - K. Rodgers
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - A. Thiel
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - V. A. Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - A. B. te Pas
- Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
| | - S. B. Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- The Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
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Pryor EJ, Davies IM, Crossley KJ, Thiel AM, McGillick EV, Rodgers K, Nitsos I, Kitchen MJ, Blank DA, Hooper SB. Assessing lung aeration using ultrasound after birth in near-term lambs at risk of respiratory distress. Front Pediatr 2023; 11:1148443. [PMID: 37284289 PMCID: PMC10239949 DOI: 10.3389/fped.2023.1148443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/02/2023] [Indexed: 06/08/2023] Open
Abstract
Background Optimizing respiratory support after birth requires real-time feedback on lung aeration. We hypothesized that lung ultrasound (LUS) can accurately monitor the extent and progression of lung aeration after birth and is closely associated with oxygenation. Methods Near-term (140 days gestation, term ∼147 days), spontaneously breathing lambs with normal (controls; n = 10) or elevated lung liquid levels (EL; n= 9) were delivered by Caesarean section and monitored for four hours after birth. LUS (Phillips CX50, L3-12 transducer) images and arterial blood gases were taken every 5-20 min. LUS images were analyzed both qualitatively (grading) and quantitatively (using the coefficient of variation of pixel intensity (CoV) to estimate the degree of lung aeration), which was correlated with the oxygen exchange capacity of the lungs (Alveolar-arterial difference in oxygen; AaDO2). Results Lung aeration, measured using LUS, and the AaDO2 improved over the first 4 h after birth. The increase in lung aeration measured using CoV of pixel intensity, but not LUS grade, was significantly reduced in EL lambs compared to controls (p = 0.02). The gradual decrease in AaDO2 after birth was significantly correlated with increased lung aeration in both control (grade, r2 = 0.60, p < 0.0001; CoV, r2 = 0.54, p < 0.0001) and EL lambs (grade, r2 = 0.51, p < 0.0001; CoV, r2 = 0.44, p < 0.0001). Conclusions LUS can monitor lung aeration and liquid clearance after birth in spontaneously breathing near-term lambs. Image analysis techniques (CoV) may be able detect small to moderate differences in lung aeration in conditions with lung liquid retention which are not readily identified using qualitative LUS grading.
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Affiliation(s)
- E. J. Pryor
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - I. M. Davies
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - K. J. Crossley
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - A. M. Thiel
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - E. V. McGillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - K Rodgers
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - I Nitsos
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - M. J. Kitchen
- School of Physics and Astronomy, Monash University, Melbourne, VIC, Australia
| | - D. A. Blank
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Monash Newborn, Monash Children’s Hospital, Clayton, VIC, Australia
| | - S. B. Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
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Amberg BJ, DeKoninck PLJ, Kashyap AJ, Skinner SM, Rodgers KA, McGillick EV, Deprest JA, Hooper SB, Crossley KJ, Hodges RJ. Placental gas exchange during amniotic carbon dioxide insufflation in sheep. Ultrasound Obstet Gynecol 2021; 57:305-313. [PMID: 31765050 DOI: 10.1002/uog.21933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
OBJECTIVE Insufflation of the amniotic cavity with carbon dioxide (CO2 ) is used clinically to improve visibility during complex fetoscopic surgery. Insufflation with heated, humidified CO2 has recently been shown to reduce fetal hypercapnia and acidosis in sheep, compared with use of cold and dry CO2 , but the underlying mechanisms are unclear. The aim of this study was to investigate whether differences in placental CO2 and oxygen (O2 ) exchange during insufflation with heated and humidified vs cold and dry CO2 could explain these findings. METHODS Thirteen fetal lambs at 105 days of gestation (term, 146 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and instrumented with an umbilical artery catheter, an umbilical vein catheter and a common umbilical vein flow probe. Arterial and venous catheters and flow probes were also inserted into the maternal uterine circulation. Six ewes were insufflated with cold, dry CO2 (22°C; 0-5% humidity) and seven with heated, humidified CO2 (40°C; 95-100% humidity) at 15 mmHg for 180 min. Blood-flow recordings and paired arterial and venous blood gases were sampled from uterine and umbilical vessels. Rates of placental CO2 and O2 exchange were calculated. RESULTS After 180 min of insufflation, fetal survival was 33% (2/6) using cold, dry CO2 and 71% (5/7) using heated, humidified CO2 . By 120 min, fetuses insufflated with heated, humidified CO2 had lower arterial CO2 levels and higher arterial pH compared to those insufflated with cold, dry gas. Insufflation decreased significantly placental gas exchange in both groups, as measured by rates of both (i) fetal CO2 clearance and O2 uptake and (ii) maternal O2 delivery and CO2 uptake from the fetal compartment. CONCLUSIONS Lower arterial CO2 and higher pH levels in fetuses insufflated with heated and humidified, compared to cold and dry, CO2 could not be explained by differences in placental gas exchange. Instead, heated and humidified insufflation appeared to reduce fetal CO2 absorption from the uterus, supporting its use in preference to cold, dry CO2 . © 2019 International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- B J Amberg
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - P L J DeKoninck
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - A J Kashyap
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - S M Skinner
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
| | - K A Rodgers
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
| | - E V McGillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - J A Deprest
- Department of Obstetrics and Gynaecology, Division Woman and Child, University Hospitals Leuven, Leuven, Belgium
- Department of Development and Regeneration, Cluster Organ Systems, Faculty of Medicine, KU Leuven, Leuven, Belgium
| | - S B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - K J Crossley
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - R J Hodges
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
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Kashyap AJ, Dekoninck PLJ, Rodgers KA, Thio M, Mcgillick EV, Amberg BJ, Skinner SM, Moxham AM, Russo FM, Deprest JA, Hooper SB, Crossley KJ, Hodges RJ. Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia. Ultrasound Obstet Gynecol 2019; 54:506-516. [PMID: 31364206 DOI: 10.1002/uog.20415] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 07/06/2019] [Accepted: 07/11/2019] [Indexed: 06/10/2023]
Abstract
OBJECTIVES Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH). METHODS DH was surgically induced at approximately 80 days' gestation in 16 lamb fetuses (term in lambs is approximately 147 days). From 105 days' gestation, ewes received either sildenafil (0.21 mg/kg/h intravenously) or saline infusion until delivery (n = 8 fetuses in each group). At approximately 138 days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120 min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs. RESULTS Lung-to-body-weight ratio (0.016 ± 0.001 vs 0.013 ± 0.001; P = 0.06) and dynamic lung compliance (0.8 ± 0.2 vs 0.7 ± 0.2 mL/cmH2 O; P = 0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120 min after cord clamping than in controls (0.6 ± 0.1 vs 2.2 ± 0.6 mmHg/(mL/min); P = 0.002). Pulmonary arterial pressure was also lower (46 ± 2 vs 59 ± 2 mmHg; P = 0.048) and pulmonary blood flow higher (25 ± 3 vs 8 ± 2 mL/min/kg; P = 0.02) in DH-sildenafil than in DH-saline lambs at 120 min. Throughout the 120-min ventilation period, the partial pressure of arterial carbon dioxide tended to be lower in DH-sildenafil lambs than in controls (63 ± 8 vs 87 ± 8 mmHg; P = 0.057), and there was no significant difference in partial pressure of arterial oxygen between the two groups. CONCLUSIONS Sustained maternal antenatal sildenafil infusion reduced pulmonary arterial pressure and increased pulmonary blood flow in DH lambs for the first 120 min after birth. These findings of improved pulmonary vascular function are consistent with improved pulmonary vascular structure seen in two previous animal models. The data support the rationale for a clinical trial investigating the effect of antenatal sildenafil in reducing the risk of neonatal pulmonary hypertension in infants with CDH. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.
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Affiliation(s)
- A J Kashyap
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - P L J Dekoninck
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Erasmus MC, Rotterdam, The Netherlands
| | - K A Rodgers
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - M Thio
- Newborn Research Centre, The Royal Women's Hospital, Melbourne, Australia
- Department of Obstetrics and Gynaecology, The University of Melbourne, Australia
| | - E V Mcgillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - B J Amberg
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - S M Skinner
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - A M Moxham
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - F M Russo
- Department of Obstetrics and Gynaecology, Division of Woman and Child, University Hospitals Leuven, Leuven, Belgium
| | - J A Deprest
- Department of Obstetrics and Gynaecology, Division of Woman and Child, University Hospitals Leuven, Leuven, Belgium
- Institute for Women's Health, University College London Hospital, London, UK
| | - S B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - K J Crossley
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - R J Hodges
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
- Monash Women's and Newborn Program, Monash Health, Melbourne, Australia
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Amberg BJ, Hodges RJ, Kashyap AJ, Skinner SM, Rodgers KA, McGillick EV, Deprest JA, Hooper SB, Crossley KJ, DeKoninck PLJ. Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model. Ultrasound Obstet Gynecol 2019; 53:340-347. [PMID: 30461102 PMCID: PMC6635737 DOI: 10.1002/uog.20180] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/30/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
OBJECTIVE Partial amniotic carbon dioxide (CO2 ) insufflation (PACI) is used to improve visualization and facilitate complex fetoscopic surgery. However, there are concerns about fetal hypercapnic acidosis and postoperative fetal membrane inflammation. We assessed whether using heated and humidified, rather than cold and dry, CO2 might reduce the impact of PACI on the fetus and fetal membranes in sheep. METHODS Twelve fetal lambs of 105 days' gestational age (term = 145 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and arterial catheters and flow probes were inserted surgically. The 10 surviving fetuses were returned to the uterus, which was then closed and insufflated with cold, dry (22 °C at 0-5% humidity, n = 5) or heated, humidified (40 °C at 100% humidity, n = 5) CO2 at 15 mmHg for 180 min. Fetal membranes were collected immediately after insufflation for histological analysis. Physiological data and membrane leukocyte counts, suggestive of membrane inflammation, were compared between the two groups. RESULTS After 180 min of insufflation, fetal survival was 0% in the group which underwent PACI with cold, dry CO2 , and 60% (n = 3) in the group which received heated, humidified gas. While all insufflated fetuses became progressively hypercapnic (PaCO2 > 68 mmHg), this was considerably less pronounced in those in which heated, humidified gas was used: after 120 min of insufflation, compared with those receiving cold, dry gas (n = 3), fetuses undergoing heated, humidified PACI (n = 5) had lower arterial partial pressure of CO2 (mean ± standard error of the mean, 82.7 ± 9.1 mmHg for heated, humidified CO2 vs 170.5 ± 28.5 for cold, dry CO2 during PACI, P < 0.01), lower lactate levels (1.4 ± 0.4 vs 8.5 ± 0.9 mmol/L, P < 0.01) and higher pH (pH, 7.10 ± 0.04 vs 6.75 ± 0.04, P < 0.01). There was also a non-significant trend for fetal carotid artery pressure to be higher following PACI with heated, humidified compared with cold, dry CO2 (30.5 ± 1.3 vs 8.7 ± 5.5 mmHg, P = 0.22). Additionally, the median (interquartile range) number of leukocytes in the chorion was significantly lower in the group undergoing PACI with heated, humidified CO2 compared with the group receiving cold, dry CO2 (0.7 × 10-5 (0.5 × 10-5 ) vs 3.2 × 10-5 (1.8 × 10-5 ) cells per square micron, P = 0.02). CONCLUSIONS PACI with cold, dry CO2 causes hypercapnia, acidosis, hypotension and fetal membrane inflammation in fetal sheep, raising potential concerns for its use in humans. It seems that using heated, humidified CO2 for insufflation partially mitigates these effects and this may be a suitable alternative for reducing the risk of fetal acid-base disturbances during, and fetal membrane inflammation following, complex fetoscopic surgery. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- B. J. Amberg
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
| | - R. J. Hodges
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
| | - A. J. Kashyap
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
| | - S. M. Skinner
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
| | - K. A. Rodgers
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
| | - E. V. McGillick
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
| | - J. A. Deprest
- Institute of Woman's HealthUniversity College LondonLondonUK
- Department of Development and Regeneration, Cluster Organ Systems, Faculty of MedicineKU LeuvenLeuvenBelgium
| | - S. B. Hooper
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
| | - K. J. Crossley
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
| | - P. L. J. DeKoninck
- The Ritchie Centre, Hudson Institute of Medical ResearchMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyMonash UniversityMelbourneVictoriaAustralia
- Department of Obstetrics and GynaecologyErasmus MC‐Sophia Children's HospitalRotterdamThe Netherlands
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Sobotka KS, Ong T, Polglase GR, Crossley KJ, Moss TJM, Hooper SB. The effect of oxygen content during an initial sustained inflation on heart rate in asphyxiated near-term lambs. Arch Dis Child Fetal Neonatal Ed 2015; 100:F337-43. [PMID: 25922189 DOI: 10.1136/archdischild-2014-307319] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 03/22/2015] [Indexed: 11/03/2022]
Abstract
OBJECTIVE At birth, an initial sustained inflation (SI) uniformly aerates the lungs, increases arterial oxygenation and rapidly improves circulatory recovery in asphyxiated newborns. We hypothesised that lung aeration, in the absence of an increase in arterial oxygenation, can increase heart rate (HR) in asphyxiated near-term lambs. INTERVENTIONS Lambs were delivered and instrumented at 139±2 days of gestation. Asphyxia was induced by umbilical cord clamping and then delaying the onset of ventilation until mean carotid arterial pressures (CAPs) had decreased <20 mm Hg. Lambs then received a single 30-s SI using nitrogen (N2; n=6), 5% oxygen (O2; n=6), 21% O2 (n=6) or 100% O2 (n=6) followed by ventilation in air for 30 min. MAIN OUTCOME MEASURES HR, CAP and pulmonary blood flow (PBF) were continuously recorded. RESULTS HR and PBF increased more quickly in lambs resuscitated with 100% and 21% O2 than with 5% O2 or N2. HR and PBF recovery in the 5% O2 group was delayed relative to all other oxygen SI groups. HR in 5%, 21% and 100% O2 groups reached 100 bpm before the SI was complete. HR and PBF in the N2 group did not increase until 10 s after the SI was completed and ventilation was initiated with air. CAP tended to increase quicker in all O2 groups than in N2 group. CONCLUSIONS Oxygen content during an SI is important for circulatory recovery in asphyxiated lambs. This increase in HR is likely driven by the increase in PBF and venous return to the heart.
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Affiliation(s)
- K S Sobotka
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia
| | - T Ong
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia
| | - G R Polglase
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia Department of Obstetrics and Gynaecology, Monash University, Clayton, Australia
| | - K J Crossley
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia
| | - T J M Moss
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia Department of Obstetrics and Gynaecology, Monash University, Clayton, Australia
| | - S B Hooper
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia Department of Obstetrics and Gynaecology, Monash University, Clayton, Australia
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Flecknoe SJ, Crossley KJ, Zuccala GM, Searle JE, Allison BJ, Wallace MJ, Hooper SB. Increased lung expansion alters lung growth but not alveolar epithelial cell differentiation in newborn lambs. Am J Physiol Lung Cell Mol Physiol 2006; 292:L454-61. [PMID: 17028266 DOI: 10.1152/ajplung.00095.2006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although increased lung expansion markedly alters lung growth and epithelial cell differentiation during fetal life, the effect of increasing lung expansion after birth is unknown. We hypothesized that increased basal lung expansion, caused by ventilating newborn lambs with a positive end-expiratory pressure (PEEP), would stimulate lung growth and alter alveolar epithelial cell (AEC) proportions and decrease surfactant protein mRNA levels. Two groups of lambs were sedated and ventilated with either 0 cmH(2)O PEEP (controls, n = 5) or 10 cmH(2)O PEEP (n = 5) for 48 h beginning at 15 +/- 1 days after normal term birth. A further group of nonventilated 2-wk-old lambs was used for comparison. We determined wet and dry lung weights, DNA and protein content, a labeling index for proliferating cells, surfactant protein mRNA expression, and proportions of AECs using electron microscopy. Although ventilating lambs for 48 h with 10 cmH(2)O PEEP did not affect total lung DNA or protein, it significantly increased the proportion of proliferating cells in the lung when compared with nonventilated 2-wk-old controls and lambs ventilated with 0 cmH(2)O PEEP (control: 2.6 +/- 0.5%; 0 PEEP: 1.9 +/- 0.3%; 10 PEEP: 3.5 +/- 0.3%). In contrast, no differences were observed in AEC proportions or surfactant protein mRNA levels between either of the ventilated groups. This study demonstrates that increases in end-expiratory lung volumes, induced by the application of PEEP, lead to increased lung growth in mechanically ventilated 2-wk-old lambs but do not alter the proportions of AECs.
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Affiliation(s)
- S J Flecknoe
- Fetal and Neonatal Research Group, Department of Physiology, Monash University, Victoria, Australia.
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Crossley KJ, Walker DW, Beart PM, Hirst JJ. Characterisation of GABA(A) receptors in fetal, neonatal and adult ovine brain: region and age related changes and the effects of allopregnanolone. Neuropharmacology 2000; 39:1514-22. [PMID: 10854896 DOI: 10.1016/s0028-3908(99)00222-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Progesterone metabolites acting via GABA(A) receptors suppress central nervous system (CNS) activity. The aim of the present study was to examine binding characteristics of GABA(A) receptors in fetal, newborn and adult sheep brains using [(35)S]TBPS, and to determine the effects of allopregnanolone on this binding. Receptor affinity (K(D)) and density (B(MAX)) in the brainstem were not different in fetal, newborn (1-2 days old) and adult brains. In the hypothalamus K(D) and B(MAX) increased significantly in the fetus between 85 and 128 days gestation, and were then similar to postnatal and adult values. In the frontal cortex K(D) and B(MAX) increased progressively between 85 days and term ( approximately 147 days gestation), and were then not different from postnatal and adult values. The K(i) values for the GABA(A) receptor antagonist picrotoxin was similar at all ages. Allopregnanolone inhibited [(35)S]TBPS binding in the presence of 5 microM GABA, but enhanced binding in the absence of GABA. These results show that (i), functional GABA(A) receptors are present in the fetal brain from at least 85 days gestation; (ii), 3alpha-pregnane steroids modify receptor affinity in the late gestation fetal brain; and (iii) there are region-specific changes in GABA(A) receptor binding parameters. Steroid modulation of the GABA(A) receptor in the fetal brain is likely to influence fetal CNS activity in late gestation.
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Affiliation(s)
- K J Crossley
- Department of Physiology, Monash University, Victoria 3168, Clayton, Australia.
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Abstract
The high rate of progesterone synthesis by the placenta in late gestation exposes the ovine fetus to high concentrations of progesterone and its metabolites that may affect activity of the fetal brain. The aim of this study was to determine the effect of inhibiting maternal progesterone synthesis on sleep-wake activity in fetal sheep. Fetal and maternal vascular catheters, a fetal tracheal catheter, and electrodes for recording fetal electrocortical (ECoG), electro-ocular (EOG) and nuchal muscle electromyographic (EMG) activity were implanted. At 128-131 days gestation, progesterone production was inhibited by an injection of trilostane (50 mg), a 3beta-hydroxysteroid dehydrogenase inhibitor. Vehicle solution or progesterone (3 mg h(-1)) was then infused into the ewe between 6 and 12 h after the trilostane treatment. Maternal progesterone concentrations were significantly reduced from 1-24 h after trilostane treatment (P < 0.05) when followed by vehicle infusion. Fetal breathing movements (FBM), EOG, nuchal muscle EMG, and behavioural arousal increased 12 h after trilostane treatment (P < 0.05). In contrast, there was no change in fetal arousal, EOG, EMG or FBM activities when progesterone was infused after the trilostane treatment. These findings show that progesterone can influence fetal behaviour, and indicates that normal progesterone production tonically suppresses arousal, or wakefulness in the fetus.
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Affiliation(s)
- K J Crossley
- Department of Physiology, Monash University, Clayton, Vic, Australia
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