The findings were similar when analysed according to whether patients were mechanically ventilated [ SVV 0.68 ( 0.63-0 .77 ) ; PPV 0.69 ( 0.61-0 .77 ) ] or breathing spontaneously [ SVV 0.69 ( 0.61-0 .77 ) ; PPV 0.63 ( 0.56-0 .72 ) ] .