Role of Low Dose Preoperative Dexmedetomidine in Preventing Tourniquet Induced Hypertension in Paediatric Orthopaedic upper Limb Surgeries during General Anaesthesia.

Background: Pneumatic Tourniquets are commonly used in orthopaedic surgery of the extremities to reduce bleeding and to provide a clear field to the surgeon, but severe pain often complicates the tourniquet inflation. Although the mechanism of tourniquet induced hypertension (TIH)is not well understood, the autonomic nervous system plays an important role. Hence, Dexmedetomidine, a potent a2-adrenoceptor agonist may prevent hyper adrenergic responses and can be of prophylactic value for tourniquet induced hypertension. Methods: Forty American Society of Anesthesiologists (ASA) physical status class I and II children, aged 5-12 years, posted for Orthopaedic surgery of upper limbs under general anaesthesia with tourniquet application were included in the study. They were randomly assigned to receive intravenous Dexmedetomidine (Group D; n=20) or normal saline (Group C; n=20) before tourniquet inflation. Incidence of TIH, Mean Arterial blood pressure and heart rate were recorded. Results: There were no significant differences between the baseline characteristics. The incidence of TIH in group D was significantly less than the group C (20%) as compared to group D (70%).There was significant increase in the heart rate of placebo group after 30 minutes of tourniquet inflation while there was minimal variability of heart rate in the group D. In the group D, arterial pressure was not significantly changed, but in the group C, the arterial pressure was significantly increased after 20 minutes of tourniquet inflation. No significant adverse effects were noted in any group. Conclusion: Preoperative low dose intravenous Dexmedetomidine prevents tourniquetinduced hypertension in paediatric patients undergoing general anaesthesia for upper limb surgeries.

Effect of Stellate Ganglion Block on Tourniquet Induced Hypertension / 대한마취과학회지

BACKGROUND: Tourniquet induced hypertension, defined as a more than 30% increase in either systolic or diastolic arterial pressure in patients with a tourniquet inflated for at least an hour, may develop despite adequate anesthesia for surgical procedure. The mechanism is uncertain. We investigated the effect of stellate ganglion block (SGB) on tourniquet induced arterial pressure and heart rate changes. METHODS: Twenty-two patients of ASA physical status class 1 and 2, scheduled for lower extremity surgery using a tourniquet, were randomly assigned into two groups (SGB group, Control group). SGB was done before induction, and anesthesia was maintained with 1.5-2.0 vol% sevoflurane and 50% N20 in O2 with endotracheal intubation. The changes of heart rate, systolic, diastolic blood pressure, end tidal CO2 and end tidal sevoflurane concentration were measured before induction, 10 minutes after induction, 10, 30, and 60 minutes after tourniquet inflation, just before tourniquet deflation and 10 minutes after tourniquet deflation. RESULTS: Heart rate increased significantly at 10 minutes after induction and 10 minutes after tourniquet inflation compared to before induction in SGB group. In both groups, systolic arterial pressure increased significantly just before tourniquet deflation compared to before induction, and there was no difference between groups. In SGB group, diastolic arterial pressure decreased significantly compared to control group at 30 minutes after tourniquet inflation. CONCLUSIONS: Preoperative stellate ganglion block was not effective in blunting tourniquet induced hypertension.

Tourniquet Induced Hypertension and Vital Sign Changes in Patients with Total Knee Replacement Arthroplasty under General Anesthesia with Enflurane or Propofol / 대한마취과학회지

BACKGROUND: The tourniquet is associated with severe hemodynamic changes and tourniquet-induced hypertension (T-HTN). Propofol is preferred as an anesthetic agent for rapid induction and recovery, and less nausea and vomiting. The aim of this study was to find the difference in hemodynamic changes and the T-HTN in patients with total knee replacement arthroplasty receiving enflurane or propofol anesthesia. METHODS: One hundred patients underwent total knee replacement arthroplasty were divided into four groups; enflurane-control (n = 22), enflurane-elderly (n = 28), propofol-control (n = 22), propofol-elderly (n = 28). Mean arterial blood pressure (MAP), heart rate (HR) and end-tidal CO2 (PETCO2) were recorded throughout the operations of each group. Statistical analysis was done using repeated measures of ANOVA, chi-square test (P < 0.05). RESULTS: MAP increased in the propofol group during the tourniquet inflation period compared to the period before tourniquet inflation. The incidence of T-HTN in the propofol group (58%) was higher than that of the enflurane group (36%). HR increased in the enflurane group just after tourniquet inflation. PETCO2 decreased during 20 60 minutes after tourniquet inflation in the propofol group (P < 0.05). MAP decreased and PETCO2 increased during the 1, 5 minutes after tourniquet deflation in all groups. There were minimal HR changes after tourniquet deflation in all groups. CONCLUSIONS: T-HTN occurrence and MAP were shown to be higher in the propofol anesthesia and both enflurane and propofol can be used as an anesthetic agent for total knee replacement arthroplasty without complications.