Pulse oximetry and end tidal carbon dioxide monitoring

Hackett, Tim

doi:10.1016/s0195-5616(02)00042-6

Cited by 18 publications

(8 citation statements)

References 9 publications

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“…The pulse oximeter gives a non-invasive estimate of arterial oxygen saturation which correlates well with arterial oxygen saturation measured in arterial blood samples (Hackett, 2002). Therefore pulse oximetry readings gave us a good indicator of general oxygenation in the rats.…”

Section: Respiratory Parameters With Alfaxalone Anaesthetic Protocolsmentioning

confidence: 67%

The safety, efficacy and neuromotor effects of the neurosteroid anaesthetic alfaxalone in rats

Lau¹

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Rodents are routinely anaesthetised for husbandry and biomedical research purposes. All anaesthetics carry a degree of risk, complications and side effects. An ideal anaesthetic for rodents is safe, predictable, alleviates pain and distress and can be performed without specialist training. A survey was created to identify anaesthetic agents frequently administered to rodents currently utilised by the research community. Findings indicated injectable anaesthetics were very commonly used and complications were often associated with use, highlighting the lack of a safe, predictable laboratory rodent anaesthetic protocol.Alfaxalone is a neuroactive steroid injectable anaesthetic agent with a high margin of safety, and is commonly used in veterinary anaesthesia as the Alfaxan® formulation. I sought to establish whether alfaxalone could be used as an injectable anaesthetic agent for laboratory rodents. A plasma pharmacokinetics study was performed using IV and IP Alfaxan® in adult female Wistar rats (7-10 weeks). Mean T 1/2elim for 2 and 5 mg.kg -1 IV was short (~17 minutes), but could not be estimated for IP dosing due to sustained plasma levels for up to 60 minutes after injection. Cl p for IV injection was calculated at 24.5% and 23% of cardiac output respectively. The observed C max was 2.99 mg.L -1 for IP administration, and 2.2 ± 0.9 and 5.2 ± 1.3 mg.L -1 for 2 and 5 mg.kg -1 IV administration respectively. AUC 0-60 was 96 min.mg.L -1 for IP dosing. The relative bioavailability for IP dosing was 26% and 28%, compared to IV doses of 2 and 5mg.kg -1 respectively. Alfaxalone given IP caused longer sleep times than IV dosing, although anaesthesia was not induced in 30% of rats.Importantly, all rats exhibited muscle twitching after alfaxalone administration. I then sought to test whether combining IP injection of Alfaxalone with common premedication agents could improve anaesthetic induction rates and reduce muscle twitching, to provide a viable anaesthetic regimen for rats. Medetomidine (0.5 mg.kg -1 ), medetomidine-butorphanol (0.35 mg.kg -1 -0.2 mg.kg -1 ), Acetylpromazine (ACP) -methadone (3 mg.kg -1 -0.7 mg.kg -1 ) and ACP-xylazine (3 mg.kg -1 -3 mg.kg -1 )were administered IP 10 minutes prior to IP alfaxalone (20 mg.kg -1 ). ACP-xylazine, medetomidine and medetomidine-butorphanol all significantly reduced twitching. Medetomidine-butorphanol provided surgical anaesthesia without prolonged recovery and provided an adequate plane of anaesthesia for short painful surgical procedures.However, none of these premedication agents fully eliminated alfaxalone-induced muscle twitching. I therefore carried out electrophysiological studies of motor neurons (MN), to determine the mechanism causing neuromotor excitation in response to alfaxalone. Previous data has shown that alfaxalone can modulate strychnine-sensitive glycinergic receptors, which may, in part, contribute to the adverse neuromotor excitatory responses manifested as muscle twitching during alfaxalone anaesthesia. The 3 effects of alfaxalone on inhibito...

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Section: Respiratory Parameters With Alfaxalone Anaesthetic Protocolsmentioning

confidence: 67%

The safety, efficacy and neuromotor effects of the neurosteroid anaesthetic alfaxalone in rats

Lau¹

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“…ETCO 2 reflects the PaCO 2 in a variety of species , provided ventilation and perfusion are matched normally. 23,24 PaCO 2 is expected to be approximately 3-5 mmHg higher than ETCO 2 in healthy small animal patients, although there may be a 5-12 mmHg difference in anaesthetized horses in dorsal recumbency. 25 If there is a high ventilation/perfusion ratio, for example due to increased alveolar dead space secondary to poor pulmonary perfusion, the difference between ETCO 2 and PaCO 2 increases.…”

Section: Discussionmentioning

confidence: 96%

“…25 If there is a high ventilation/perfusion ratio, for example due to increased alveolar dead space secondary to poor pulmonary perfusion, the difference between ETCO 2 and PaCO 2 increases. 23 Alveolar-arterial gas tension gradients in pregnant sheep have not been investigated. Without comparing ETCO 2 and PaCO 2 in our study we cannot preclude a widened alveolar-arterial gradient, and thus cannot directly compare the adequacy of ventilation between the two groups of sheep.…”

Section: Discussionmentioning

confidence: 99%

Pressure and volume controlled mechanical ventilation in anaesthetized pregnant sheep

Davis

Musk

2014

Lab Anim

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Optimal mechanical ventilation of the pregnant ewe during anaesthesia is of vital importance for maintaining fetal viability. This study aimed to compare peak inspiratory pressure (PIP), oxygenation and cardiovascular parameters with pressure-control (PCV) or volume-control (VCV) mechanical ventilation of anaesthetized pregnant sheep. Twenty ewes at 110 days gestation underwent general anaesthesia in dorsal recumbency for fetal surgery in a research setting. All the sheep were mechanically ventilated; one group with PCV (n ¼ 10) and another with VCV (n ¼ 10) to maintain normocapnia. PIP, direct arterial blood pressure, heart rate, arterial pH and arterial oxygen tension were recorded. PIP was lower in the PCV group (P < 0.001). Arterial oxygen tension was higher in the PCV group (P ¼ 0.013). Mean and diastolic pressures were lower in the PCV group (P ¼ 0.029 and P ¼ 0.047, respectively). Both VCV and PCV provide adequate oxygenation of pregnant sheep anaesthetized in dorsal recumbency, though PCV may provide superior oxygenation at a lower PIP.

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“…Sidestream capnography slightly increases airway resistance and also draws 125 to 500 mL of gas/min from the patient, but these factors would be negligible in most foals. 38 Pulse oximetry has technical limitations, including a limited ability of the instrument to detect an arterial pulse in patients with impaired arterial perfusion from shock, hypothermia, or hypovolemia. Motion artifact in conscious foals is also a common limitation.…”

Section: Discussionmentioning

confidence: 99%

Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals

Wong¹,

Alcott²,

Wang³

et al. 2011

javma

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Objective-To determine agreement between indirect measurements of end-tidal partial pressure of carbon dioxide (Petco2) and saturation of hemoglobin with oxygen as measured by pulse oximetry (Spo2) with direct measurements of Paco2 and calculated saturation of hemoglobin with oxygen in arterial blood (Sao2) in conscious healthy and ill foals. Design-Validation study. Animals-10 healthy and 21 ill neonatal foals. Procedures-Arterial blood gas analysis was performed on healthy and ill foals examined at a veterinary teaching hospital to determine direct measurements of Paco2 and Pao2 along with Sao2. Concurrently, Petco2 was measured with a capnograph inserted into a naris, and Spo2 was measured with a reflectance probe placed at the base of the tail. Paired values were compared by use of Pearson correlation coefficients, and level of agreement was assessed with the Bland-Altman method. Results-Mean ± SD difference between Paco2 and Petco2 was 0.1 ± 5.0 mm Hg. There was significant strong correlation (r = 0.779) and good agreement between Paco2 and Petco2. Mean ± SD difference between Sao2 and Spo2 was 2.5 ± 3.5%. There was significant moderate correlation (r = 0.499) and acceptable agreement between Sao2 and Spo2.

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Pulse oximetry and end tidal carbon dioxide monitoring

Cited by 18 publications

References 9 publications

The safety, efficacy and neuromotor effects of the neurosteroid anaesthetic alfaxalone in rats

The safety, efficacy and neuromotor effects of the neurosteroid anaesthetic alfaxalone in rats

Pressure and volume controlled mechanical ventilation in anaesthetized pregnant sheep

Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals

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