ABSTRACT
Objective To evaluate the effects of controlled heart rate (HR) on the nasal mucosa blood flow (NMBF) during nitroglycerin (NTG)-induced controlled hypotension in the patients undergoing endoscopic sinus surgery.Methods Seventy-two ASA physical status Ⅰ or Ⅱ patients of both sexes,weighing 49-85 kg,with body mass index ＜ 30 kg/m2 and Lund-Mackay score between 7 and 15,scheduled for elective endoscopic sinus surgery,were randomly divided into 2 groups (n =36 each) using a random number table:NTG group (group N) and NTG-induced controlled hypotension combined with esmolol group (group E).Controlled hypotension was induced with continuous iv infusion of NTG at 1-3 μg· kg-1 · min-1 before surgery,and MAP was maintained at 70％ of baseline value until the end of surgery.In group E,when MAP was decreased to 70％ of baseline value,esmolol was infused intravenously at 20-100 μg· kg-1 · min-1,the consumption was adjusted according to the HR,and the HR was maintained at 60-70 beats/min until termination of controlled hypotension.Before induction of anesthesia (T0),after topical anesthesia (T1),at 15,30 and 45 min of controlled hypotention (T2-4),and at packing hemostasis at the end of surgery (T5),HR,stroke volume (SV) and cardiac output (CO) were recorded.NMBF was monitored at T1-T4.Blood samples were drawn from the radial artery and jugular blub at T1-T5 for blood gas analysis.Arteriovenous blood O2 difference (Da-jvO2) and cerebral O2 extraction rate (CERO2) were calculated.The quality of the surgical field in terms of blood loss was rated by the same attending surgeon.Results Compared with group N,HR,SV and CO at T2-T5,NMBF at T2-T4 and the volume of blood loss in the surgical field was significantly decreased in group E (P ＜ 0.01).There was no significant difference in Da-jvO2 and CERO2 between the two groups (P ＞ 0.05).Conclusion Controlled HR (60-70 beats/min) can reduce the NMBF during nitroglycerin-induced controlled hypotension in the patients undergoing endoscopic sinus surgery without causing tissue hypoperfusion.