Effects of Low Dose Ketamine on Tourniquet-induced Haemodynamic Responses during General Anaesthesia

Comparison of bolus administration effects of lidocaine on preventing tourniquet-induced hypertension in patients undergoing general anesthesia: a randomized controlled trial

Background

This study assessed the effect of a single bolus administration of lidocaine on the prevention of tourniquet-induced hypertension (TIH) and compared the effect of lidocaine to that of ketamine in patients undergoing general anesthesia.

Methods

This randomized, controlled, double-blind study included 75 patients who underwent lower limb surgery using a tourniquet. The patients were administered lidocaine (1.5 mg/kg, n = 25), ketamine (0.2 mg/kg, n = 25) or placebo (n = 25). The study drugs were administered intravenously 10 min before tourniquet inflation. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured before tourniquet inflation, after tourniquet inflation for 60 min at 10 min intervals, and immediately after tourniquet deflation. The incidence of TIH, defined as an increase of 30% or more in SBP or DBP during tourniquet inflation, was also recorded.

Results

SBP, DBP, and HR increased significantly over time in the control group compared to those in the lidocaine and ketamine groups for 60 min after tourniquet inflation (P < 0.001, P < 0.001, and P = 0.007, respectively). The incidence of TIH was significantly lower in the lidocaine (n = 4, 16%) and ketamine (n = 3, 12%) group than in the control group (n = 14, 56%) (P = 0.001).

Conclusion

Single-bolus lidocaine effectively attenuated blood pressure increase due to tourniquet inflation, with an effect comparable to that of bolus ketamine.

Reducing the Hypertensive Effects of the Prolonged Surgical Tourniquet Using a Dual-Cuff Strategy: A Prospective Randomized Controlled Trial

We evaluated whether moving the "line of crush" from thigh to the calf before onset of tourniquet-mediated hypertension would prevent or diminish it. We also evaluated any change in pain or functional outcome. Twenty adult patients were recruited and randomly assigned to either control or intervention groups. Inclusion criteria: any willing participant >18 years old with foot and/or ankle pathology requiring an operation lasting >90 minutes. Exclusion criteria included contraindication to general anesthesia, peripheral neuropathy affecting lower limbs of any etiology, or chronic pain requiring regular opiate analgesia. The intervention group received a thigh tourniquet for 60 minutes, after which a calf tourniquet was inflated and the thigh tourniquet was deflated. The control group received only a thigh tourniquet throughout surgery. At 90 minutes, the control group had mean arterial pressure of 86.8 mmHg, compared with the intervention group at 76.3 mmHg (p ≤ .014). At end of surgery, the difference had increased further (control 98.1 mmHg, intervention 78.3 mmHg (p ≤ .001). Moving the line of crush during limb tourniquet application prevents development of the hypertensive response. For cases in which a prolonged tourniquet application is required, a dual-tourniquet technique will prevent intraoperative hypertension and may influence long-term pain and function.

A randomized controlled trial to assess the effect of a ketamine infusion on tourniquet hypertension during general anaesthesia in patients undergoing upper and lower limb surgery

BACKGROUND

Tourniquet hypertension arising from tourniquet inflation remains a primary concern to the anaesthetist. One drug commonly used to manage tourniquet hypertension is ketamine. No studies have examined the effect of ketamine on tourniquet hypertension for a period of more than one hour or an infusion of the same.

OBJECTIVE

To compare the effect of an intravenous infusion of ketamine versus placebo on tourniquet induced hypertension in patients undergoing upper and lower limb surgery under general anaesthesia.

METHODS

Forty six adult patients scheduled for upper and lower limb surgery under general anaesthesia were randomized into two equal groups. The ketamine group received an intravenous bolus of 0.1mg/kg of ketamine followed by an infusion of 2ug/kg/min. The saline group received an intravenous bolus of physiological saline followed by an infusion of saline. All the patients were reviewed post-operatively. Data of the baseline characteristics, haemodynamic changes, post-tourniquet pain and side effects were collected. If post-tourniquet pain was present post-operatively, a visual analogue scale (VAS) was used to assess its severity.

RESULTS

46 patients successfully completed the trial. There were no significant differences between the groups for baseline patient demographics. The incidence of tourniquet hypertension was higher in the saline group (26.1%) compared with ketamine group (4.6%) with a 95% confidence interval. The difference was shown to be statistically significant ('P'<0.05). There was an increase in systolic blood pressure after 60 minutes of tourniquet inflation in the saline group but the difference was not statistically significant('P'>0.866). There were no significant differences between the groups as regards diastolic blood pressure and heart rate. VAS scores did not differ between the two groups. Statistically, there was no difference found between the two groups. Side effects were minimal in the ketamine group whilst in the saline group, nausea and vomiting were predominant but were also not statistically significant.

CONCLUSION

Based on the results of this study, there was a difference in the proportion of tourniquet hypertension between the ketamine and saline groups for patients undergoing upper and lower limb orthopaedic surgery under general anaesthesia.

Tourniquet application during anesthesia: "What we need to know?"

Tourniquets are routinely and safely used in limb surgeries throughout the world. Tourniquet application alters normal physiology. Healthy patients tolerate these physiological changes well, but the physiological changes may not be well-tolerated by patients with poor cardiac function. This review discusses the physiological changes associated with tourniquet use, safe practice and provides the latest updates regarding tourniquet use. A systematic literature search of PubMed, MEDLINE, ScienceDirect, and Google Scholar was done. The search results were limited to the randomized controlled trials and systemic reviews. The papers are summarized in this review.

Comparison of ketorolac and low-dose ketamine in preventing tourniquet-induced increase in arterial pressure

BACKGROUND AND AIMS

Application of tourniquet during orthopaedic procedures causes pain and increase in blood pressure despite adequate anaesthesia and analgesia. In this study, we compared ketorolac with ketamine in patients undergoing elective lower limb surgery with tourniquet in order to discover if ketorolac was equally effective or better than ketamine in preventing tourniquet-induced hypertension.

METHODS

Approval was granted by the Institutional Ethics Review Committee and informed consent was obtained from all participants. A randomised double-blinded controlled trial with 38 patients each in the ketamine and ketorolac groups undergoing elective knee surgery for anterior cruciate ligament repair or reconstruction was conducted. Induction and maintenance of anaesthesia were standardised in all patients, and the minimum alveolar concentration of isoflurane was maintained at 1.2 throughout the study period. One group received ketamine in a dose of 0.25 mg/kg and the other group received 30 mg ketorolac 10 min before tourniquet inflation. Blood pressure was recorded before induction of anaesthesia (baseline) and at 0, 10, 20, 30, 40, 50, and 60 min after tourniquet inflation.

RESULTS

The demographic and anaesthetic characteristics were similar in the two groups. At 0 and 10 min, tourniquet-induced rise in blood pressure was not observed in both groups. From 20 min onward, both systolic and diastolic blood pressures were significantly higher in ketorolac group compared to ketamine group.

CONCLUSION

We conclude that ketamine is superior to ketorolac in preventing tourniquet-induced increases in blood pressure.