Pressure and volume controlled mechanical ventilation in anaesthetized pregnant sheep

Davis, Jennifer; Musk, GC

doi:10.1177/0023677214543842

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The most appropriate ventilation strategy for pregnant sheep is also not known but pressure-controlled ventilation may provide superior oxygenation at lower inflation pressures when compared with volume-controlled ventilation. 11 Manipulating the position of the ewe during surgery can be problematic as good surgical access is important to minimize the duration of surgery and anaesthesia. In this study surgical access was facilitated by positioning the ewe in dorsal recumbency in the Trendelenburg position.…”

Section: Discussionmentioning

confidence: 99%

“…The physiological parameters of the ewe during anaesthesia were stable and within the expected range for anaesthetized sheep. 9,11 IPPV settings created a mild respiratory acidosis and intravenous fluid therapy was sufficient for maintenance of the mean arterial blood pressure as planned. The ventilator parameters were successfully adjusted to maintain normocapnia based upon capnography but the arterial–end-tidal CO 2 difference indicates a degree of ventilation and perfusion mismatching in the lungs and specifically the presence of physiological dead space.…”

Section: Discussionmentioning

confidence: 99%

“…Premedication, induction and maintenance of anaesthesia were performed as previously described. 11 Following physical examination the ewes were premedicated with a combination of acepromazine (0.03 mg/kg, ACP 2 injection, 2 mg/mL; Ceva Delvet Pty Ltd, Glenorie, NSW, Australia) and buprenorphine (0.01 mg/kg, Temgesic, 0.3 mg/mL; Reckitt Benckiser, Melrose Park, NSW, Australia) by intramuscular injection 30–40 min prior to the induction of anaesthesia. Anaesthesia was induced with a combination of midazolam (0.25 mg/kg, Midazolam injection, 5 mg/mL; Pfizer Australia Pty Ltd, Melrose Park, NSW, Australia) and ketamine (5 mg/kg, Ketamil, 100 mg/mL; Troy Laboratories, Glendenning, NSW, Australia) by intravenous injection and the trachea was subsequently intubated (endotracheal tube 8.5 mm internal diameter, cuffed; Portex Ltd, Ashford, Kent, UK).…”

Section: Methodsmentioning

confidence: 99%

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Maternal and fetal arterial blood gas data during general anaesthesia for caesarean delivery of preterm twin lambs

Musk

Kemp

2015

Lab Anim

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Much remains to be understood with regards the effects of prolonged anaesthesia on maternal and fetal haemodynamics and oxygenation. With the aim of improving anaesthetic management of pregnant sheep undergoing recovery surgery under anaesthesia, paired maternal and fetal arterial blood samples were collected during caesarean delivery of twin preterm lambs to document the blood gas status of the ewe and fetus. Twenty-one Merino twin pregnant ewes at 126 (AE1) days of gestation were anaesthetized for caesarean delivery of their fetuses. Arterial blood samples were collected from the radial artery of the ewe and umbilical artery of the fetus at the point of delivery. There was a significant difference between maternal PaCO 2 and end-tidal CO 2 and alveolar and arterial PaO 2 , indicating ventilation perfusion mismatch. Interestingly, the ewes were anaemic but the fetuses were not. These data underscore the need to undertake further work to determine the optimal anaesthetic regimen for twin pregnant ewes at different gestational ages in a biomedical research setting.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Maternal and fetal arterial blood gas data during general anaesthesia for caesarean delivery of preterm twin lambs

Musk

Kemp

2015

Lab Anim

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“…Anesthesia was maintained and monitored as previously described. 6 With the sheep positioned in sternal recumbency, the wool over the catheter insertion site in the lumbosacral area was clipped, and the skin was prepared by using 0.5% chlorhexidine in 70% ethanol. Under strict aseptic conditions, the skin overlying the insertion site was infiltrated with local anesthetic (2 mL per sheep; 0.5% bupivacaine in adrenaline 1:200 000, Marcain Hospira, Lake Forest, IL).…”

Section: Neurologic Complications Associated With Transdermal Placement Of Intrathecal Catheters In Sheepmentioning

confidence: 99%

Neurologic Complications Associated with Transdermal Placement of Intrathecal Catheters in Sheep

et al. 2018

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A study using an ovine model of transdermal intrathecal catheterization was planned to investigate the neurotoxicity of magnesium sulfate. Nonpregnant Merino cross ewes (n = 8; age, 5 y; weight, 55.0 ± 6.5 kg) were anesthetized for placement of a lumbar intrathecal catheter. The study protocol defined a 5-d recovery period after introduction of the catheter before the administration of test substances (2 mL of 0.9% saline or 50 or 150 mg MgSO4) followed by euthanasia 1 wk later. Although 3 sheep successfully completed the study as planned, one of the remaining 5 sheep was withdrawn when the catheter was accidentally dislodged 2 d after anesthesia; another was withdrawn because of persistent neurologic deficits of the left hindlimb and intense pruritus during the first 24 h after placement of the catheter; and the remaining 3 animals experienced unacceptable complications within the first 4 h of administration of the test substance. These complications included hindlimb weakness, intense irritation or pruritus of the hindlimbs, recumbency, inability to stand, spasm of the hindlimb, and arching of the back. Postmortem examination of 4 sheep with clinical signs revealed similar gross findings: acute, segmental myelomalacia and hemorrhage within the spinal cord parenchyma in the region of the catheter. Histologic changes included segmental areas of acute myelomalacia, consistent with the intraparenchymal placement of the catheter. Postmortem CT imaging of 3 sheep confirmed the location of the catheter within the spinal cord. Procedural refinement for the placement of intrathecal catheters in sheep by avoiding an invasive surgical procedure was unsuccessful. We therefore recommend a complete or partial surgical approach for the insertion of an intrathecal catheter in sheep or fluoroscopy or ultrasonography intraoperatively to confirm correct placement of the catheter.

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“…We expected sheep lungs to be able to meet these requirements. 4,5 We aimed to develop a low-cost and widely available donation after circulatory death (DCD) lung research model, with the use of ex vivo lung perfusion (EVLP) and sheep lungs sourced from an abattoir.…”

Section: Introductionmentioning

confidence: 99%

Establishing an economical and widely accessible donation after circulatory death animal abattoir model for lung research using ex vivo lung perfusion

Zhang

Moeslund

et al. 2022

Artificial Organs

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Background Ex vivo lung perfusion (EVLP), is a platform that allows simultaneous testing and treatment of the lungs. However, use of EVLP is costly and requires access to lab animals and accompanying facilities. To increase the use of EVLP for research, we developed a method to perform EVLP using abattoir procured lungs. Furthermore, we were also able to significantly decrease costs. Methods Six pair of lungs were procured from abattoir sheep. The lungs were then flushed and stored in ice for 3 h. A low‐flow (20% of cardiac output) approach, a tidal volume of 6 ml/kg bodyweight and total perfusion time of 3 h were chosen. Perfusion fluids and circuits were self‐made. Lung biopsies, perfusate collection, respiratory values, circulatory pressures were recorded and hourly blood gas analyses were performed. Results Mean pO2 remained stable from 60 min (49.3 ± 7.1 kPa) to 180 min (51.5 kPa ± 8.0), p = 0.66. Pulmonary artery pressure remained ≤15 mm Hg and the left atrial pressure remained between 3 and 5 mm Hg and peak respiratory pressures ≤20 cmH2O. Lactate dehydrogenase increased from start (96.3 ± 56.4 U/L) to the end of perfusion (315.8 ± 85.0 U/L), p < 0.05. No difference was observed in ATP between procurement and post‐EVLP, 129.7 ± 37.4 μmol/g protein to 132.0 ± 23.4 μmol/g, p = 0.92. Conclusions Sheep lungs, acquired from an abattoir, can be ex vivo perfused under similar conditions as lab animal lungs with similar results regarding e.g., oxygenation and ATP restoration. Furthermore, costs can be significantly reduced by making use of this abattoir model. By increasing accessibility and lowering costs for experiments using lung perfusion, more results may be achieved in the field of lung diseases.

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Pressure and volume controlled mechanical ventilation in anaesthetized pregnant sheep

Cited by 10 publications

References 22 publications

Maternal and fetal arterial blood gas data during general anaesthesia for caesarean delivery of preterm twin lambs

Maternal and fetal arterial blood gas data during general anaesthesia for caesarean delivery of preterm twin lambs

Neurologic Complications Associated with Transdermal Placement of Intrathecal Catheters in Sheep

Establishing an economical and widely accessible donation after circulatory death animal abattoir model for lung research using ex vivo lung perfusion

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