The influence of mechanical ventilation on physiological parameters in ball pythons (Python regius)

Jakobsen, Sashia L.; Williams, Catherine J.; Wang, Tobias; Bertelsen, Mads F.

doi:10.1016/j.cbpa.2017.02.012

Cited by 16 publications

(4 citation statements)

References 32 publications

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“…high blood capacitance coefficients or blood gas partition coefficients) because they are less limited by blood convective transport. It may therefore be advisable to mildly over-ventilate reptilian lungs to hasten both onset and elimination of anaesthesia 30 . In research, although difficult in clinical practice, this can be combined with supplementing the inspired gases with CO 2 to avoid respiratory alkalosis 30,32 .…”

Section: Discussionmentioning

confidence: 99%

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Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model

Williams

Malte

et al. 2020

Sci Rep

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The use of inhalational anaesthesia is ubiquitous in terrestrial vertebrates. Given the dependence of these agents on delivery by the cardiorespiratory system, we developed a new computational model predicting equilibration of inhaled anaesthetics in mammalian and ectotherm conditions including the ability of reptiles to maintain vascular shunts. A multi-compartment model was constructed from simultaneously-solved equations, verified by comparison to the literature for endo and ectotherm physiology. The time to 90% equilibration of anaesthetic in arterial blood (t90) is predicted and used to compare anaesthetics and physiologies. The five to tenfold lower cardiac output and minute ventilation of ectothermic vertebrates is predicted to slow equilibration times by five to ten times leading to 90% equilibration in ectotherm arterial blood of over 200 min, compounded by reduction in body temperature, and the extent of right-to-left vascular shunts. The impact of these findings is also influenced by the solubility coefficient of the anaesthetic, such that at net right-to-left shunt fractions of over 0.8, sevoflurane loses the advantage of faster equilibration, in comparison with isoflurane. We explore clinical strategies to regulate anaesthetic uptake in ectotherms by managing convectional flow especially by supportive ventilation and reduction of the right-to-left shunt.

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Section: Discussionmentioning

confidence: 99%

“…Reptiles often lose respiratory drive at surgical depths of anaesthesia and artificial ventilation is typically required, but needs to be matched to the low reptilian metabolism to maintain normal PaCO 2 30 , 31 . However, given the steep dependence of t 90 on (Fig.…”

Section: Discussionmentioning

confidence: 99%

Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model

Williams

Malte

et al. 2020

Sci Rep

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“…To place the arterial catheter and ECG electrodes, each snake was anesthetized in a sealed container with isoflurane (IsoFlo Vet 100%; Orion Pharma Animal Health AS). After ∼15 min, the snakes were intubated endotracheally with soft polyethylene (made from pipettes; Sarstedt AG & Co.) for mechanical ventilation (Anesthesia Workstation; Hallowell EMC) with a mixture of oxygen and isoflurane (Fluotec Mark 3 vaporizer; Simonsen & Well A/S) at ∼200 ml min −1 −1 kg −1 (4 breaths min −1 ) and a maximum airway pressure at 15 cm H 2 O ( Jakobsen et al, 2017 ). Initially 5% isoflurane was given until full reflexes were lost, and then the supply was reduced to 2%.…”

Section: Methodsmentioning

confidence: 99%

Catecholamines are key modulators of ventricular repolarization patterns in the ball python (Python regius)

Boukens

Joyce

Kristensen

et al. 2021

Journal of General Physiology

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Ectothermic vertebrates experience daily changes in body temperature, and anecdotal observations suggest these changes affect ventricular repolarization such that the T-wave in the ECG changes polarity. Mammals, in contrast, can maintain stable body temperatures, and their ventricular repolarization is strongly modulated by changes in heart rate and by sympathetic nervous system activity. The aim of this study was to assess the role of body temperature, heart rate, and circulating catecholamines on local repolarization gradients in the ectothermic ball python (Python regius). We recorded body-surface electrocardiograms and performed open-chest high-resolution epicardial mapping while increasing body temperature in five pythons, in all of which there was a change in T-wave polarity. However, the vector of repolarization differed between individuals, and only a subset of leads revealed T-wave polarity change. RNA sequencing revealed regional differences related to adrenergic signaling. In one denervated and Ringer’s solution–perfused heart, heating and elevated heart rates did not induce change in T-wave polarity, whereas noradrenaline did. Accordingly, electrocardiograms in eight awake pythons receiving intra-arterial infusion of the β-adrenergic receptor agonists adrenaline and isoproterenol revealed T-wave inversion in most individuals. Conversely, blocking the β-adrenergic receptors using propranolol prevented T-wave change during heating. Our findings indicate that changes in ventricular repolarization in ball pythons are caused by increased tone of the sympathetic nervous system, not by changes in temperature. Therefore, ventricular repolarization in both pythons and mammals is modulated by evolutionary conserved mechanisms involving catecholaminergic stimulation.

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“…The trachea was intubated with an adapted 10‐gauge catheter (Angiocath IV catheter; BD Canada), and the isoflurane concentration was then maintained at 1%‐2% throughout the surgery. Mechanical ventilation was performed using a circle rebreathing system (Anesthesia WorkStation; Hallowell EMC) delivering 5 breaths per min with a tidal volume of 25 ml/kg based on results of a recent study (Jakobsen, Williams, Wang, & Bertelsen, ). Body temperature was maintained at approximately 30°C.…”

Section: Methodsmentioning

confidence: 99%

Pharmacokinetics of midazolam and its major metabolite 1‐hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations

Larouche

Johnson

Beaudry

et al. 2019

Vet Pharm & Therapeutics

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Midazolam is a benzodiazepine with sedative, muscle relaxant, anxiolytic, and anticonvulsant effects. Twelve ball pythons (Python regius) were used in a parallel study evaluating the pharmacokinetics of 1 mg/kg midazolam following a single intracardiac (IC) or intramuscular (IM) administration. Blood was collected from a central venous catheter placed 7 days prior, or by cardiocentesis, at 15 time points starting just prior to and up to 72 hr after drug administration. Plasma concentrations of midazolam and 1‐hydroxymidazolam were determined by the use of high‐performance liquid chromatography tandem‐mass spectrometry and pharmacokinetic parameters were estimated using noncompartmental analysis. The mean ± SD terminal half‐lives of IC and IM midazolam were 12.04 ± 3.25 hr and 16.54 ± 7.10 hr, respectively. The area under the concentration‐time curve extrapolated to infinity, clearance, and apparent volume of distribution in steady‐state of IC midazolam were 19,112.3 ± 3,095.9 ng*hr/ml, 0.053 ± 0.008 L hr−1 kg−1, and 0.865 ± 0.289 L/kg, respectively. The bioavailability of IM midazolam was estimated at 89%. Maximum plasma concentrations following an IM administration were reached 2.33 ± 0.98 hr and 24.00 ± 14.12 hr postinjection for midazolam and 1‐hydroxymidazolam, respectively, and 22.33 ± 20.26 hr postinjection for 1‐hydroxymidazolam following IC administration.

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The influence of mechanical ventilation on physiological parameters in ball pythons (Python regius)

Cited by 16 publications

References 32 publications

Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model

Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model

Catecholamines are key modulators of ventricular repolarization patterns in the ball python (Python regius)

Pharmacokinetics of midazolam and its major metabolite 1‐hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations

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