Table 1.

Cardiorespiratory variables, arterial blood–gas analysis, and dobutamine requirements in 10 isoflurane-anesthetized horses undergoing bilateral fetlock arthroscopy.

Variable		PRE	POST
fR (breaths min−1)	P1	3 [1, 11]	6 [1, 9]
	P2	3 [2, 8]	5 [1, 7]
	P3	4 [3, 7]	4 [3, 7]
	P4	4 [2, 5]	4 [2, 5]
VTi (mL kg−1)	P1	14 [10, 15]	9 [8, 14]
	P2	14 [11, 15]	11 [9, 13]a
	P3	16 [9, 20]	11 [9, 13]
	P4	16 [10, 21]	12 [9, 13]
VTe (mL kg−1)	P1	14 [8, 24]	8 [8, 14]
	P2	13 [9, 15]	9 [8, 9]a
	P3	14 [8, 19]	10 [8, 11]
	P4	15 [10, 21]	12 [8, 13]
IT (s)	P1	3 [1, 4]	2 [1, 3]
	P2	3 [1, 5]	3 [2, 4]
	P3	3 [2, 6]	3 [2, 8]
	P4	3 [2, 6]	4 [2, 6]
${\dot{V}}_{\text{Ei}}$ (mL kg−1 min−1)	P1	51 [24, 10]	62 [14 76]
	P2	64 [31, 85]	61 [60, 66]
	P3	61 [39, 69]	55 [22, 68]
	P4	48 [47, 86]	33 [12, 48]
${\dot{V}}_{\text{Ee}}$ (mL kg−1 min−1)	P1	46 [24, 90]	54 [14, 73]
	P2	59 [30, 70]	49 [40, 58]
	P3	59 [37, 64]	53 [21, 55]
	P4	46 [44, 89]	32 [13, 47]
VTi/IT (mL kg−1 s−1)	P1	3 [1, 3]	5 [1, 5]
	P2	4 [2, 6]	5 [5, 5]
	P3	4 [2, 8]	5 [2, 5]
	P4	6 [2, 8]	3 [1, 4]
PE′CO2 (mmHg)	P1	41 [31, 48]	40 [33, 50]
	P2	43 [38, 54]	45 [40, 46]
	P3	45 [37, 56]	44 [38, 50]
	P4	47 [39, 49]	40 [37, 53]
HR (beats min−1)	P1	41 [31, 48]	40 [33, 50]
	P2	43 [38, 54]	45 [40, 46]
	P3	45 [37, 46]	44 [38, 50]
	P4	47 [39, 49]	40 [37, 43]
MAP (mmHg)	P1	54 [50, 60]	61 [51, 62]
	P2	56 [53, 59]	61 [57, 77]
	P3	64 [53, 58]	69 [59, 88]
	P4	73 [62, 76]	63 [62, 85]
Dobutamine requirements by period (μg kg−1)	P1	18 [9, 36]	15 [6, 33]
	P2	18 [15, 27]	15 [0, 24]
	P3	9 [0, 21]	3 [0, 3]
	P4	0 [0, 6]	6 [0, 15]
T (°C)	P1	35.0 [34.8, 36.6]	35.4 [34.7, 36.2]
	P2	34.9 [34.4, 36.3]	35.1 [34.6, 36.2]
	P3	34.4 [33.9, 36.1]	34.8 [34.4, 35.8]
	P4	34.1 [33.5, 36.0]	34.7 [34.2, 35.4]
pH	G1	7.35 [7.27, 7.37]	7.33 [7.31, 7.35]
	G2	7.28 [7.22, 7.36]	7.28 [7.20, 7.33]
	G3	7.29 [7.32, 7.23]	7.29 [7.19, 7.30]
PaCO2 (mmHg)	G1	56 [48, 76]	56 [55, 66]
	G2	73 [61, 75]	66 [60, 83]
	G3	75 [69, 85]	71 [60, 91]
PaO2 (mmHg)	G1	322 [74, 399]	356 [284, 442]
	G2	186 [171, 287]	254 [135, 391]
	G3	108 [72, 148]	125 [74, 285]

Horses received morphine and phenylbutazone before skin incision (PRE, n = 5) or at the end of the procedure (POST, n = 5). Data are reported as median [min, max]. f_R, respiratory frequency; V_Ti, inspired tidal volume; V_Te, expired tidal volume; ${\dot{V}}_{\text{Ei}}$, inspired minute volume; ${\dot{V}}_{\text{Ee}}$, expired minute volume; V_Ti/IT, inspiratory flow rate; P_ECO₂, expired pressure of carbon dioxide; HR, heart rate; MAP, mean arterial blood pressure; PaCO₂, arterial partial pressure of carbon dioxide; PaO₂, arterial partial pressure of oxygen; P1, from 30 to 15 min before skin incision; P2, from 15 min to time of skin incision; P3, from skin incision to 15 min after incision; P4 from 15 to 30 min after skin incision. Arterial gas analysis periods: G1, once when the horse was instrumented, G2, once when skin incision was performed, and G3, at the end of the procedure. Data are reported as median [min, max].

^aIndicates statistically significant differences between groups (p < 0.05).