Complex sentence: Of crucial importance for success in surgical prophylaxis is the timing of administration of short-acting antibiotics, as persistent antimicrobial activity throughout the entire operation is essential; the longer a surgical procedure lasts, the longer an appropriate antibiotic tissue level must be maintained.
Split into simpler sentences: Of crucial importance for success in surgical prophylaxis is the timing of administration of short-acting antibiotics. The longer a surgical procedure lasts, the longer an appropriate antibiotic tissue level must be maintained.