Maintained inspiratory activity during proportional assist ventilation in surfactant-depleted cats early after surfactant instillation: phrenic nerve and pulmonary stretch receptor activity

Table 2 Slowly adapting pulmonary stretch receptor (PSR) activity and phrenic nerve activity (PNA) during CPAP and PAV before and after lung lavage and after instillation of surfactant.

		CPAP	PAV	*CPAP-PAV p (ANOVA)*
		*Mean±S.D*.	*Mean±S.D*.
Before lung lavage	Peak PSR f _imp *, impulsessec** ^-1	64 ± 19	67 ± 20	NS
	Time to peak PSR activity, sec	1.48 ± 0.34	1.35 ± 0.10	NS
	PSR f _imp per P _tp *, impulsessec** ^-1 *kPa ^-1	1.78 ± 0.33	1.53 ± 0.25	NS
	PNA duration, sec	1.80 ± 0.38	1.64 ± 0.31	NS
	PNA amplitude, AU	0.58 ± 0.50	0.49 ± 0.34	NS
	Mean PNA, AU/sec	0.38 ± 0.42	0.34 ± 0.30	NS
After lung lavage	Peak PSR f _imp *, impulsessec** ^-1	45 ± 37 ^a	88 ± 33 ^a	p <0.0001
	Time to peak PSR activity, sec	1.18 ± 0.27 ^a	0.78 ± 0.22 ^a	p <0.0001
	PSR f _imp per P _tp *, impulsessec** ^-1 *kPa ^-1	0.42 ± 0.29 ^a	0.46 ± 0.19 ^a	NS
	PNA duration, sec	1.38 ± 0.22 ^a	1.10 ± 0.48^a	p <0.05
	PNA amplitude, AU	0.68 ± 0.51	0.46 ± 0.40	p <0.03
	Mean PNA, AU/sec	0.53 ± 0.48 ^a	0.52 ± 0.58	NS
After surfactant instillation	Peak PSR f _imp *, impulsessec** ^-1	53 ± 36	82 ± 17	p <0.0001
	Time to peak PSR activity, sec	1.00 ± 0.16 ^b	0.80 ± 0.09	p <0.0001
	PSR f _imp per P _tp *, impulsessec** ^-1 *kPa ^-1	0.59 ± 0.25 ^b	0.55 ± 0.11 ^b	NS
	PNA duration, sec	0.97 ± 0.24 ^b	0.91 ± 0.09	p <0.01
	PNA amplitude, AU	0.75 ± 0.55	0.61 ± 0.64	NS
	Mean PNA, AU/sec	0.81 ± 0.69	0.67 ± 0.71 ^b	p <0.01

^a significant difference between pre- and post-lavage values
^b significant difference between post-lavage value and value after surfactant instillation
^a,b p < 0.05. ANOVA; two-tailed paired Student's t-test. S.D., standard deviation; NS, non-significant; AU, arbitrary units; PSR f_imp, instantaneous impulse frequency of PSR; P_tp, transpulmonary pressure

ISSN: 1465-993X