Heart–lung interactions during neurally adjusted ventilatory assist

Table 5 Right ventricular echocardiographic data

Doppler flow profile in the right ventricular outflow tract (n = 8)	PSVlow	PSVal	PSVhigh	NAVAlow	NAVAal	NAVAhigh	P value
							Level	Mode	Interaction
End expiration
Acceleration time (milliseconds)	82 ± 14	83 ± 13	80 ± 11	82 ± 16	77 ± 14	89 ± 18	0.484	0.68	0.141
Flow period (milliseconds)	242 ± 25	256 ± 36	256 ± 37	240 ± 23	242 ± 27	243 ± 28	0.072	0.127	0.285
Maximum flow velocity (m/second)	0.8 ± 0.2	0.9 ± 0.3	0.8 ± 0.3	0.7 ± 0.3	0.8 ± 0.2	0.9 ± 0.3	0.047	0.012	0.465
Velocity time integral (cm)	13 ± 2	14 ± 3	14 ± 3	13 ± 2	13 ± 3	14 ± 3	0.009	0.063	0.178
End inspiration
Acceleration time (milliseconds)	86 ± 15	81 ± 15	84 ± 17	81 ± 12	88 ± 20	91 ± 17	0.62	0.259	0.296
Flow period (milliseconds)	250 ± 27	242 ± 25	231 ± 33	250 ± 21	261 ± 29	251 ± 30	0.02	0.067	0.028
Maximum flow velocity (m/second)	0.8 ± 0.2	0.8 ± 0.3	0.7 ± 0.2	0.7 ± 0.3	0.9 ± 0.3	0.8 ± 0.3	0.168	0.154	0.166
Velocity time integral (cm)	13 ± 3	13 ± 3	12 ± 3	13 ± 2	14 ± 3	14 ± 3	0.154	0.046	0.025
Inspiratory values as percentage of expiratory values
cAcceleration time (%)	104 ± 8	98 ± 8	105 ± 10	101 ± 13	115 ± 9	104 ± 11	0.617	0.217	0.012
Flow period (%)	103 ± 2	94 ± 3	91 ± 2	104 ± 2	107 ± 3	103 ± 2	<0.001	<0.001	<0.001
Maximum flow velocity (%)	99 ± 2	92 ± 7	86 ± 8	100 ± 3	106 ± 5	97 ± 4	<0.001	0.003	<0.001
Velocity time integral (%)	101 ± 3	89 ± 6	83 ± 9	103 ± 4	109 ± 5	100 ± 4	<0.001	<0.001	<0.001

Data presented as mean ± standard deviation. Doppler flow profiles in the right ventricular outflow tract could be obtained from eight patients. Absolute values at end expiration did not differ between NAVA and PSV. To describe cyclic changes, the inspiratory values are given as a percentage of the corresponding expiratory value. P values from repeated-measures analysis of variance (within-subject factors: ventilation mode, support level). NAVA, neurally adjusted ventilator assist; NAVAal, adequate NAVA level identified by a titration procedure; NAVAhigh, 200% of the adequate NAVA level; NAVAlow, 50% of the adequate NAVA level; PSV, pressure support ventilation; PSVal, adequate level of pressure support ventilation identified on clinical grounds; PSVhigh, 150% of adequate PSV level; PSVlow, 50% of adequate PSV level.

ISSN: 1364-8535