Volatile Anaesthetic Depression of the Carotid Body Chemoreflex-Mediated Ventilatory Response to Hypoxia: Directions for Future Research

Table 1

Summary of studies examining effect of volatile anaesthetics on carotid body responses.

Study	Agent	Number of animals	Dose (%)	Dose (MAC)	NMB	Method	Animal	Anaesthetic effect for hypoxic response	Anaesthetic effect for hypercapnic response
Biscoe and Millar 1968 [56]	Halothane	1	1.00	1.250	Y	IA-CSN	Cat	1.04	—
Biscoe and Millar 1968 [56]	Halothane	1	2.00	2.500	Y	IA-CSN	Cat	0.69	0.50¶
Davies et al. 1982 [57]	Halothane	6	0.50	0.625	Y	IA-CSN	Cat	0.58	0.49
Berkenbosch et al. 1982 [63]	Halothane	2	0.80*	1.000	N	ABP	Cat	—	0.58
Berkenbosch et al. 1982 [63]	Halothane	3	1.00*	1.250	N	ABP	Cat	—	0.50
van Dissel et al. 1985 [62]	Halothane	6	1.00*	1.250	N	ABP	Cat	0.54	0.68
Morray et al. 1996 [60]	Halothane	6	0.50	0.625	Y	IA-CSN	Cat†	1.84	—
Morray et al. 1996 [60]	Halothane	6	1.00	1.250	Y	IA-CSN	Cat†	0.20	—
Ide et al. 1999 [58]	Halothane	10	0.10	0.125	Y	CBP-PN	Cat	0.94	—
Ide et al. 1999 [58]	Halothane	10	0.80	1.000	Y	CBP-PN	Cat	0.11	—
Ponte and Sadler 1989 [61]	Halothane	5	0.75*	0.938	Y	IA-CSN	Rabbit	1.00	1.17
Ponte and Sadler 1989 [61]	Halothane	5	0.75*	0.938	Y	IA-CSN	Cat	0.92	1.08
Ponte and Sadler 1989 [61]	Enflurane	4	0.80*	0.500	Y	IA-CSN	Rabbit	0.67	0.96
Ponte and Sadler 1989 [61]	Enflurane	7	0.80*	0.500	Y	IA-CSN	Cat	0.96	1.00
Ponte and Sadler 1989 [61]	Isoflurane	4	0.75*	0.682	Y	IA-CSN	Rabbit	0.89	0.88
Ponte and Sadler 1989 [61]	Isoflurane	8	0.75*	0.682	Y	IA-CSN	Cat	0.67	0.96
Joensen et al. 2000 [59]	Isoflurane	3	0.10	0.091	N	IA-CSN	Rabbit	0.69	0.75
Joensen et al. 2000 [59]	Isoflurane	6	1.00	0.909	N	IA-CSN	Rabbit	0.92	1.75

The order of studies in the table is chronological for each agent studied. The columns show the agent used, the number of animals studies, the dose in % and then in MAC, whether (Y) or not (N) neuromuscular blockade was used, the experimental preparation, the animal species, the standardised anaesthetic effect for hypoxic response, and the standardised anaesthetic effect for hypercapnic response. The experimental preparations were (column 7) intact animal, recording from carotid sinus nerve (IA-CSN), artificial brain perfusion which separates the central from peripheral respiratory structures (ABP), and separate carotid body perfusion with recording from phrenic nerve (CBP-PN). *Only a dose range was specified, and in these cases we have used the middle of the reported range for our calculations (see text). We took the MAC for halothane to be 0.8%, for enflurane to be 1.6%, and for isoflurane to be 1.1%. †Kittens were used. ¶The dose of halothane for the hypercapnic study was 2.5% (3.125 MAC).