Inhalational Anaesthesia Quiz

WIKIQUIZ

Questions reviewed by:

Juliet Duncan BVM&S MSc DipECVAA MRCVS

1

Which would be the most appropriate breathing circuit to use in a 38kg dog? Co-axial Bain Circle Parallel Lack T-piece Magill Please select an option Incorrect. The Co-axial Bain breathing circuit is used in patients between 8-15 kg so it would be uneconomical and inappropriate in this patient. The circle breathing circuit is the only one which would be appropriate in a patient over 35kg. WikiVet Article: Breathing circuits. Correct! The circle breathing circuit is the only one which would be appropriate in a patient over 35kg. WikiVet Article: Breathing circuits. Incorrect. The parallel lack breathing circuit is used in patients between 10-35kg so it would be inappropriate in this patient. The circle breathing circuit is the only one which would be appropriate in a patient over 35kg. WikiVet Article: Breathing circuits. Incorrect. The T-piece breathing circuit is used in patients under 10kg so it would be inappropriate in this patient. The circle breathing circuit is the only one which would be appropriate in a patient over 35kg. WikiVet Article: Breathing circuits. Incorrect. The Magill breathing circuit is used in patients between 10-35kg so it would be inappropriate in this patient. The circle breathing circuit is the only one which would be appropriate in a patient over 35kg. WikiVet Article: Breathing circuits.

2

Calculate, in litres, the fresh gas flow rate for a 35kg dog with a respiratory rate of 10 bpm, using a circle breathing circuit during maintenance of anaesthesia. 3.5 - 5.25 litres 5.25 - 7.875 litres ›3.5 litres 8.75 - 10.5 litres ›0.35 litres Please select an option Incorrect. Did you calculate the fresh gas flow assuming the circle breathing circuit has a circuit factor of 1 - 1.5? Remember, gas flow is calculated using metabolic oxygen demand of 10ml/kg, which in this patient is 0.35 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the fresh gas flow assuming the circle breathing circuit has a circuit factor of 1 - 1.5 and the tidal volume was weight multiplied by 15mls? Remember, the circle breathing circuit does not have a circuit factor, gas flow is calculated using metabolic oxygen demandof 10ml/kg, which in this patient is 0.35 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the fresh gas flow as 100mls/kg? Remember, the circle breathing circuit does not have a circuit factor, gas flow is calculated using metabolic oxygen demand of 10ml/kg, which in this patient is 0.35 litres.WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the fresh gas flow assuming the circle breathing circuit has a circuit factor of 2.5 - 3? Remember, the circle breathing circuit does not have a circuit factor, gas flow is calculated using metabolic oxygen demand of 10ml/kg, which in this patient is 0.35 litres. Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. WikiVet Article: Calculating fresh gas flow. Correct! The circle breathing circuit does not have a circuit factor, gas flow is calculated using metabolic oxygen demand of 10ml/kg, which in this patient is 0.35 litres. WikiVet Article: Calculating fresh gas flow.

3

Calculate, in litres,the fresh gas flow rate for a 20kg dog with a respiratory rate of 10 bpm, using a Magill breathing circuit. 3 - 4.5 litres 5 - 6 litres 4 - 6 litres 7.5 - 9 litres 2 - 3 litres Please select an option Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 20kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 200mls. The circuit factor of a Magill is 1 - 1.5, so the fresh gas flow is 200 x 10 (respiratory rate) x 1 - 1.5 = 2 - 3 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you use a circuit factor of 2.5 - 3? Remember the circuit factor of a Magill is 1 - 1.5. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 20kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 200mls. The circuit factor of a Magill is 1 - 1.5, so the fresh gas flow is 200 x 10 (respiratory rate) x 1 - 1.5 = 2 - 3 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you use the corrrect respiratory rate? Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 20kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 200mls. The circuit factor of a Magill is 1 - 1.5, so the fresh gas flow is 200 x 10 (respiratory rate) x 1 - 1.5 = 2 - 3 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls and did you use a circuit factor of 2.5 - 3? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls and also the circuit factor of a Magill is 1 - 1.5. Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 20kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 200mls. The circuit factor of a Magill is 1 - 1.5, so the fresh gas flow is 200 x 10 (respiratory rate) x 1 - 1.5 = 2 - 3 litres. WikiVet Article: Calculating fresh gas flow. Correct! Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 20kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 200mls. The circuit factor of a Magill is 1 - 1.5, so the fresh gas flow is 200 x 10 (respiratory rate) x 1 - 1.5 = 2 - 3 litres. WikiVet Article: Calculating fresh gas flow.

4

Calculate, in litres,the fresh gas flow rate for a 25kg dog with a respiratory rate of 12 bpm, using a parallel Lack breathing circuit. 6.25 - 9.375 litres 11.25- 16.875 litres 3 - 4.5 litres 7.5 - 9 litres 4.5 - 6.75 litres Please select an option Incorrect. Did you use the corrrect respiratory rate? Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 25kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 250mls. The circuit factor of a parallel Lack is 1 - 1.5, so the fresh gas flow is 250 x 12 (respiratory rate) x 1 - 1.5 = 3 - 4.5 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls and did you use a circuit factor of 2.5 - 3? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls and also the circuit factor of a parallel Lack is 1 - 1.5. Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 25kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 250mls. The circuit factor of a parallel Lack is 1 - 1.5, so the fresh gas flow is 250 x 12 (respiratory rate) x 1 - 1.5 = 3 - 4.5 litres. WikiVet Article: Calculating fresh gas flow. Correct! Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 25kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 250mls. The circuit factor of a parallel Lack is 1 - 1.5, so the fresh gas flow is 250 x 12 (respiratory rate) x 1 - 1.5 = 3 - 4.5 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you use a circuit factor of 2.5 - 3? Remember the circuit factor of a parallel Lack is 1 - 1.5. Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 25kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 250mls. The circuit factor of a parallel Lack is 1 - 1.5, so the fresh gas flow is 250 x 12 (respiratory rate) x 1 - 1.5 = 3 - 4.5 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 25kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 250mls. The circuit factor of a parallel Lack is 1 - 1.5, so the fresh gas flow is 250 x 12 (respiratory rate) x 1 - 1.5 = 3 - 4.5 litres. WikiVet Article: Calculating fresh gas flow.

5

Calculate, in litres,the fresh gas flow rate for a 5kg dog with a respiratory rate of 16 bpm, using a T-piece breathing circuit. 0.6 - 0.72 litres 1.2 - 1.8 litres 0.8 - 1.2 litres 3 - 3.2 litres 2 - 2.4 litres Please select an option Incorrect. Did you calculate the tidal volume correctly? Remember to multiply the dogs weight by 15mls. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 5kg x 15mls (use this higher figure if the patient weighs less than 10kg) = 75mls. The circuit factor of a T-piece is 2.5 - 3, so the fresh gas flow is 75 x 16 (respiratory rate) x 2.5 - 3 = 3 - 3.2 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you use a circuit factor of 1 - 1.5? Remember the circuit factor of a T-piece is 2.5 - 3. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 5kg x 15mls (use this higher figure if the patient weighs less than 10kg) = 75mls. The circuit factor of a T-piece is 2.5 - 3, so the fresh gas flow is 75 x 16 (respiratory rate) x 2.5 - 3 = 3 - 3.2 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 10mls and did you use a circuit factor of 1 - 1.5? Remember, if the animal weighs less than 10kg, tidal volume is calculated by multiplying the weight by 15mls and also the circuit factor of a T-piece is 2.5 - 3.Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 5kg x 15mls = 75mls. The circuit factor of a T-piece is 2.5 - 3, so the fresh gas flow is 75 x 16 (respiratory rate) x 2.5 - 3 = 3 - 3.2 litres. WikiVet Article: Calculating fresh gas flow. Correct! Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 5kg x 15mls (use this higher figure if the patient weighs less than 10kg) = 75mls. The circuit factor of a T-piece is 2.5 - 3, so the fresh gas flow is 75 x 16 (respiratory rate) x 2.5 - 3 = 3 - 3.2 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 10mls? Remember, if the animal weighs less than 10kg, tidal volume is calculated by multiplying the weightby 15mls. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 5kg x 15mls = 75mls. The circuit factor of a T-piece is 2.5 - 3, so the fresh gas flow is 75 x 16 (respiratory rate) x 2.5 - 3 = 3 - 3.2 litres. WikiVet Article: Calculating fresh gas flow.

6

What is the minimum alveolar concentration (MAC) of sevoflurane in dogs? 1.3% 0.9% 2.6% 1.1% 2.4% Please select an option Incorrect. The MAC of isoflurane in dogs is 1.3%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect. The MAC of halothane in dogs is 0.9%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect.The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect. The MAC of halothane in cats is 1.1%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Correct! The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane.

8

What is the minimum alveolar concentration (MAC) of sevoflurane in cats? 1.3% 1.1% 0.9% 2.4% 2.6% Please select an option Incorrect. The MAC of isoflurane in dogs is 1.3%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect. The MAC of halothane in cats is 1.1%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect. The MAC of halothane in dogs is 0.9%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Incorrect.The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane. Correct! The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of sevoflurane is 2.4% in dogs and 2.6% in cats. WikiVet Article: sevoflurane.

9

What is the minimum alveolar concentration (MAC) of isoflurane in dogs? 1.1% 2.4% 1.6% 1.3% 0.9% Please select an option Incorrect. The MAC of halothane in cats is 1.1%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimulus. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The MAC of sevoflurane in dogs is 2.4%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimulus. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimulus. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Correct! The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimulus. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The MAC of halothane in dogs is 0.9%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimulus. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane.

10

What is the minimum alveolar concentration (MAC) of isoflurane in cats? 1.1% 2.4% 1.6% 0.9% 1.3% Please select an option Incorrect. The MAC of halothane in cats is 1.1%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The MAC of sevoflurane in dogs is 2.4%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Correct! The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The MAC of halothane in dogs is 0.9%. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane. Incorrect. The minimum alveolar concentration (MAC) is a measure of the potency of an inhalation agent. It is the minimum alveolar concentration of agent required to produce immobility of 50% of patients when exposed to a noxious stimuli. Therefore, the lower the MAC, the more potent the agent. The MAC of isoflurane is 1.3% in dogs and 1.6% in cats. WikiVet Article: Isoflurane.

11

Which inhalational agent still in clinical use sensitizes the myocardium to catecholamines? Halothane Nitrous oxide Sevoflurane Desflurane Isoflurane Please select an option Correct! Halothane sensitizes the myocardium to catecholamines and so it can potentiate arrythmias. WikiVet Article: Halothane. Incorrect. Nitrous oxide does not sensitize the myocardium to catecholamines. Halothane sensitizes the myocardium to catecholamines and so it can potentiate arrythmias. WikiVet Article: Halothane. Incorrect. Sevoflurane does not sensitize the myocardium to catecholamines. Halothane sensitizes the myocardium to catecholamines and so it can potentiate arrythmias. WikiVet Article: Halothane. Incorrect. Desflurane does not sensitize the myocardium to catecholamines. Halothane sensitizes the myocardium to catecholamines and so it can potentiate arrythmias. WikiVet Article: Halothane. Incorrect. Isoflurane does not sensitize the myocardium to catecholamines. Halothane sensitizes the myocardium to catecholamines and so it can potentiate arrythmias. WikiVet Article: Halothane.

12

Prolonged exposure to which inhalational anaesthetic agent can lead to bone marrow suppression via vitamin B12 dependent enzyme inactivation? Isoflurane Sevoflurane Halothane Desflurane Nitrous oxide Please select an option Incorrect. Isoflurane does not cause vitamin B12 dependent inactivation. Prolonged exposure to nitrous oxide can cause vitamin B12 dependent enzyme inactivation thereby causing bone marrow suppression. Since prolonged exposure means weeks to months, this is more relevant to the practitioner who may experience prolonged and repeated exposure than to the patient, and necessitates efficient scavenging and regular equipment checks Use of nitrous oxide should be avoided in animals with severe anaemia because of the reduced oxygen carrying capacity of the blood.WikiVet Article: Nitrous oxide. Incorrect. Sevoflurane does not cause vitamin B12 dependent inactivation. Prolonged exposure to nitrous oxide can cause vitamin B12 dependent enzyme inactivation thereby causing bone marrow suppression. Since prolonged exposure means weeks to months, this is more relevant to the practitioner who may experience prolonged and repeated exposure than to the patient, and necessitates efficient scavenging and regular equipment checks. Use of Nitrous oxide should be avoided in animals with severe anaemia because of the reduced oxygen carrying capacity of the blood. WikiVet Article: Nitrous oxide. Incorrect. Halothane does not cause vitamin B12 dependent inactivation.Prolonged exposure to nitrous oxide can cause vitamin B12 dependent enzyme inactivation thereby causing bone marrow suppression. Since prolonged exposure means weeks to months, this is more relevant to the practitioner who may experience prolonged and repeated exposure than to the patient, and necessitates efficient scavenging and regular equipment checks. Use of nitrous oxide should be avoided in animals with severe anaemia because of the reduced oxygen carrying capacity of the blood. WikiVet Article: Nitrous oxide. Incorrect. Desflurane does not cause vitamin B12 dependent inactivation. Prolonged exposure to nitrous oxide can cause vitamin B12 dependent enzyme inactivation thereby causing bone marrow suppression. Since prolonged exposure means weeks to months, this is more relevant to the practitioner who may experience prolonged and repeated exposure than to the patient, and necessitates efficient scavenging and regular equipment checks. Use of nitrous oxide should be avoided in animals with severe anaemia because of the reduced oxygen carrying capacity of the blood. WikiVet Article: Nitrous oxide. Correct! Prolonged exposure to nitrous oxide can cause vitamin B12 dependent enzyme inactivation thereby causing bone marrow suppression. Since prolonged exposure means weeks to months, this is more relevant to the practitioner who may experience prolonged and repeated exposure than to the patient, and necessitates efficient scavenging and regular equipment checks. Use of nitrous oxide should be avoided in animals with severe anaemia because of the reduced oxygen carrying capacity of the blood. WikiVet Article: Nitrous oxide.

13

Which inhalational anaesthetic agent should not be used in a patient with gastric dilatation and volvulus (GDV)? Sevoflurane Halothane Isoflurane Desflurane Nitrous oxide Please select an option Incorrect. Sevoflurane can be used in patients with GDV. The different solubilities of nitrous oxide and nitrogen in the blood together result in the accumulation of nitrous oxide in closed air-containing cavities within the animal's body. In small animals, abnormal accumulations of nitrogen-containing air are seen with gastric dilation volvulus or pneumothorax. As the tissues surrounding the nitrogen-containing cavity are perfused with blood containing little nitrogen and a high amounts of nitrous oxide, a large partial pressure gradient develops that favours movement of nitrous oxide into the cavity and nitrogen out of the pocket causing it to fill up with even more air. WikiVet Article: Nitrous oxide. Incorrect. Halothane can be used in patients with GDV. The different solubilities of nitrous oxide and nitrogen in the blood together result in the accumulation of nitrous oxide in closed air-containing cavities within the animal's body. In small animals, abnormal accumulations of nitrogen-containing air are seen with gastric dilation volvulus or pneumothorax. As the tissues surrounding the nitrogen-containing cavity are perfused with blood containing little nitrogen and a high amounts of nitrous oxide, a large partial pressure gradient develops that favours movement of nitrous oxide into the cavity and nitrogen out of the pocket causing it to fill up with even more air. WikiVet Article: Nitrous oxide. Incorrect. Isoflurane can be used in patients with GDV. The different solubilities of nitrous oxide and nitrogen in the blood together result in the accumulation of nitrous oxide in closed air-containing cavities within the animal's body. In small animals, abnormal accumulations of nitrogen-containing air are seen with gastric dilation volvulus or pneumothorax. As the tissues surrounding the nitrogen-containing cavity are perfused with blood containing little nitrogen and a high amounts of nitrous oxide, a large partial pressure gradient develops that favours movement of nitrous oxide into the cavity and nitrogen out of the pocket causing it to fill up with even more air. WikiVet Article: Nitrous oxide. Incorrect. Desflurane can be used in patients with GDV. The different solubilities of nitrous oxide and nitrogen in the blood together result in the accumulation of nitrous oxide in closed air-containing cavities within the animal's body. In small animals, abnormal accumulations of nitrogen-containing air are seen with gastric dilation volvulus or pneumothorax. As the tissues surrounding the nitrogen-containing cavity are perfused with blood containing little nitrogen and a high amounts of nitrous oxide, a large partial pressure gradient develops that favours movement of nitrous oxide into the cavity and nitrogen out of the pocket causing it to fill up with even more air. WikiVet Article: Nitrous oxide. Correct! The different solubilities of nitrous oxide and nitrogen in the blood together result in the accumulation of nitrous oxide in closed air-containing cavities within the animal's body. In small animals, abnormal accumulations of nitrogen-containing air are seen with gastric dilation volvulus or pneumothorax. As the tissues surrounding the nitrogen-containing cavity are perfused with blood containing little nitrogen and a high amounts of nitrous oxide, a large partial pressure gradient develops that favours movement of nitrous oxide into the cavity and nitrogen out of the pocket causing it to fill up with even more air. WikiVet Article: Nitrous oxide.

14

Calculate, in litres,the fresh gas flow rate for an 18kg dog with a respiratory rate of 14 bpm, using a co-axial Bain breathing circuit. 3.78 - 5.67 litres 9.45 - 11.34 litres 2.52 - 3.78 litres 0.63 - 0.756 litres 6.3 - 7.56 litres Please select an option Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls and did you use a circuit factor of 1 - 1.5? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls and also the circuit factor of a co-axial Bain is 2.5 - 3. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 18kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 180mls. The circuit factor of a co-axial Bain is 2.5 - 3, so the fresh gas flow is 180 x 14 (respiratory rate) x 2.5 - 3 = 6.3 - 7.56 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume by using weight multiplied by 15mls? Remember, if the animal weighs more than 10kg, tidal volume is calculated by multiplying the weight by 10mls. Also remember that a small animal anaesthetic machine delivers a maximum fresh gas flow of 8 litres so the calculated flow rate would be unachievable. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 18kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 180mls. The circuit factor of a co-axial Bain is 2.5 - 3, so the fresh gas flow is 180 x 14 (respiratory rate) x 2.5 - 3 = 6.3 - 7.56 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you use a circuit factor of 1 - 1.5? Remember the circuit factor of a co-axial Bain is 2.5 - 3. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 18kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 180mls. The circuit factor of a co-axial Bain is 2.5 - 3, so the fresh gas flow is 180 x 14 (respiratory rate) x 2.5 - 3 = 6.3 - 7.56 litres. WikiVet Article: Calculating fresh gas flow. Incorrect. Did you calculate the tidal volume correctly? Remember to multiply the dogs weight by 10mls. Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 18kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 180mls. The circuit factor of a co-axial Bain is 2.5 - 3, so the fresh gas flow is 180 x 14 (respiratory rate) x 2.5 - 3 = 6.3 - 7.56 litres. WikiVet Article: Calculating fresh gas flow. Correct! Fresh gas flow is calculated by the formula: tidal volume (weight x 10 - 15mls) x respiratory rate x circuit factor. So for this patient the tidal volume is 18kg x 10mls (use this lower figure if the patient weighs more than 10kg) = 180mls. The circuit factor of a co-axial Bain is 2.5 - 3, so the fresh gas flow is 180 x 14 (respiratory rate) x 2.5 - 3 = 6.3 - 7.56 litres. WikiVet Article: Calculating fresh gas flow.