Valdes will almost certainly miss the rest of the La Liga campaign and the World Cup after tearing a cruciate ligament in his right knee in Wednesday's 3-0 La Liga win at home to Celta Vigo and he is due to undergo surgery in Germany on Monday.
It was a bitter blow for the 32-year-old, who has probably played his last game for Barca as he is leaving his boyhood club at the end of the season. Second-choice keeper Jose Manuel Pinto has taken his place in the first team for the time being.
Martino said he had spoken to club president Josep Maria Bartomeu and sporting director Andoni Zubizarreta about the goalkeeping situation.
Under La Liga rules, clubs are allowed to register a new player if a member of their squad suffers an injury that rules them out for more than five months.
"What we have to be at the very least is informed of the alternatives and the options that we have," Martino told a news conference ahead of Saturday's La Liga game at city rivals Espanyol.
"But under normal circumstances we would continue as we are until the end of the season," added the Argentine.
Barca are through to the last eight of the Champions League, where UEFA regulations say that clubs can register a new keeper at any time during the season but only if they cannot count on the services of at least two.
As well as Pinto and Valdes, Barca also have B team goalkeeper Oier Olazabal registered in their Champions League squad.
Chasing a fifth La Liga title in six years, Barca are second in the standings with eight games left, a point behind Atletico Madrid ahead of their game at Athletic Bilbao on Saturday.
Real Madrid are two points behind Barca in third and host city rivals Rayo Vallecano.
Barca playmaker Andres Iniesta, who came off at halftime in the Celta game after feeling a twinge in a thigh muscle, is fit to face Espanyol, the club said.
Iniesta's Spain team mate Xavi is back in the squad after Martino rested him on Wednesday, while Alex Song is out with a bruised calf, they added.
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