One-Lung VentilationFluid TherapyIsotonic SolutionsColloidsRehydration SolutionsHyponatremiaPlasma SubstitutesHypovolemiaIntraoperative CarePerioperative CareColorectal SurgeryBlood Volume DeterminationWater-Electrolyte BalanceGoalsHydroxyethyl Starch DerivativesPostoperative CareSodium ChloridePostoperative Complications