Altan Sahin

Spinal 5-HT7 receptors play an important role in the antinociceptive and antihyperalgesic effects of tramadol and its metabolite, O-Desmethyltramadol, via activation of descending serotonergic pathways.

Background:Tramadol is an analgesic drug, and its mechanism of action is believed to be mediated by the &mgr;-opioid receptor. A further action of tramadol has been identified as blocking the reuptake of serotonin (5-HT). One of the most recently identified subtypes of 5-HT receptor is the 5-HT7 receptor. Thus, the authors aimed to examine the potential role of serotonergic descending bulbospinal pathways and spinal 5-HT7 receptors compared with that of the 5-HT2A and 5-HT3 receptors in the antinociceptive and antihyperalgesic effects of tramadol and its major active metabolite O-desmethyltramadol (M1) on phasic and postoperative pain models. Methods:Nociception was assessed by the radiant heat tail-flick and plantar incision test in male Balb-C mice (25-30 g). The serotonergic pathways were lesioned with an intrathecal injection of 5,7-dihydroxytryptamine. The selective 5-HT7, 5-HT2, and 5-HT3 antagonists; SB-269970 and SB-258719; ketanserin and ondansetron were given intrathecally. Results:Systemically administered tramadol and M1 produced antinociceptive and antihyperalgesic effects. The antinociceptive effects of both tramadol and M1 were significantly diminished in 5-HT-lesioned mice. Intrathecal injection of SB-269970 (10 &mgr;g) and SB-258719 (20 &mgr;g) blocked both tramadol- and M1-induced antinociceptive and antihyperalgesic effects. Ketanserin (20 &mgr;g) and ondansetron (20 &mgr;g) were unable to reverse the antinociceptive and antihyperalgesic effects of tramadol and M1. Conclusions:These findings suggest that the descending serotonergic pathways and spinal 5-HT7 receptors play a crucial role in the antinociceptive and antihyperalgesic effects of tramadol and M1.

Ketamine gargle for attenuating postoperative sore throat

BACKGROUND Tracheal intubation is a foremost cause of trauma to the airway mucosa, resulting in postoperative sore throat (POST) with reported incidences of 21-65%. We compared the effectiveness of ketamine gargles with placebo in preventing POST after endotracheal intubation. METHODS Forty-six, ASA I-II, patients undergoing elective surgery for septorhinoplasty under general anaesthesia were enrolled in this prospective, randomized, placebo-controlled, single-blind study. Patients were randomly allocated into two groups of 23 subjects each: Group C, saline 30 ml; Group K, ketamine 40 mg in saline 30 ml. Patients were asked to gargle this mixture for 30 s, 5 min before induction of anaesthesia. POST was graded at 0, 2, 4, and 24 h after operation on a four-point scale (0-3). RESULTS POST occurred more frequently in Group C, when compared with Group K, at 0, 2, and 24 h and significantly more patients suffered severe POST in Group C at 4 and 24 h compared with Group K (P<0.05). CONCLUSIONS Ketamine gargle significantly reduced the incidence and severity of POST.

Upper cervical vertebrae movement during intubating laryngeal mask, fibreoptic and direct laryngoscopy: a video-fluoroscopic study

Background and objective: Minimizing cervical vertebrae motion during endotracheal intubation is important in patients with cervical instability. The aim of this study was to compare upper cervical spine extension during endotracheal intubation using three different techniques. Methods: Duration of intubation and movement of upper cervical vertebrae during endotracheal intubation were compared in 33 patients undergoing lumbar laminectomy. Patients requiring tracheal intubation under general anaesthesia and neuromuscular blockade were randomly allocated into three groups - direct laryngoscopy, intubating laryngeal mask (LM) airway and fibreoptic laryngoscopy. The procedure was recorded by video-fluoroscopy and analysed with computer-assisted measurements. The maximum movement of the C1/C2 and C2/C3 vertebrae during intubation were obtained. Data were analysed using one-way analysis of variance with Bonferroni and Kruskal-Wallis tests. Results: We found statistically significant movement between the first and second, but not between the second and third cervical vertebrae. The mean (±SD) movement at C1/C2 was 10.2 ± 7.3° with direct laryngoscopy, 5.0 ± 6.3° with LM and 1.6 ± 3.2° with fibreoptic laryngoscopy. This difference was statistically significant (P = 0.01) between the direct and fibreoptic laryngoscopy groups. The maximum movement at C2/C3 was 2.2 ± 10.1° with direct laryngoscopy, 3.5 ± 5.1° with LM and 0.5 ± 3.2° with fibreoptic laryngoscopy. Duration of intubation was significantly longer in the intubating LM group (P < 0.001). Conclusion: We conclude that fibreoptic laryngoscopy is the more suitable intubation technique when cervical spine movement is not desired.

The effects of non-leukoreduced red blood cell transfusions on microcirculation in mixed surgical patients.

BACKGROUND The impact of the storage process on oxygen-carrying properties of red blood cells and the efficacy of red blood cell (RBC) transfusions concerning tissue oxygenation remain an issue of debate in transfusion medicine. Storage time and leukocyte content probably interact since longer storage duration is thought to cause greater accumulation of leukocyte-derived cytokines and red blood cell injury. OBJECTIVES The aim of this study was to investigate the effects of storage and the efficacy of fresh (stored for less than 1 week) versus aged (stored for more than 3 weeks) non-leukoreduced RBC transfusions on sublingual microvascular density and flow in mixed surgical patients. METHODS Eighteen surgical patients were included in this study. Patients were randomly assigned into two groups receiving fresh (Group A) and aged (Group B) RBC transfusions. Sublingual microcirculatory functional capillary density (FCD) and microvascular flow index (MFI) were assessed using orthogonal polarization spectral (OPS) imaging. Measurements and collection of blood samples were performed after induction of general anesthesia, before RBC transfusion and 30 min after the RBC transfusion ended. RESULTS In both groups RBC transfusions caused an increase in hemoglobin concentration (p<0.001). RBC transfusions increased FCD in Group A (p<0.001), while FCD remained unaffected in Group B. Changes in MFI following RBC transfusion in both groups remained unaltered. CONCLUSIONS Fresh non-leukoreduced RBC transfusions but not RBCs stored for more than 3weeks, were effective in improving microciruculatory perfusion by elevating the number of perfused microvessels in mixed surgical patients.

Use of 19F-nuclear magnetic resonance and gas chromatography-electron capture detection in the quantitative analysis of fluorine-containing metabolites in urine of sevoflurane-anaesthetized patients

1. The use of fluorine-19 nuclear magnetic resonance (19F-NMR) and gas chromatography-electron capture detection (GC-ECD) in the analysis of fluorine-containing products in the urine of sevoflurane-exposed patients was explored. 2. Ten patients were anaesthetized by sevoflurane for 135–660 min at a flow rate of 6 l min−1. Urine samples were collected before, directly after and 24 h after discontinuation of anaesthesia. 3. 19F-NMR analysis of the urines showed the presence of several fluorine-containing metabolites. The main oxidative metabolite, hexafluoroisopropanol (HFIP)-glucuronide, showed two strong quartet signals in the 19F-NMR spectrum. HFIP concentrations after β-glucuronidase treatment were quantified by 19F-nuclear magnetic resonance. Concentrations directly after and 24 h after discontinuation of anaesthesia were 131 ± 41 (mean ± SEM) and 61 ± 19 mol mg−1 creatinine, respectively. Urinary HFIP excretions correlated with sevoflurane exposure. 4. Longer scanning times enabled the measurement of signals from two compound A-derived metabolites, i.e. compound A mercapturic acid I (CAMA-I) and compound A mercapturic acid II (CAMA-II), as well as products from β-lyase activation of the respective cysteine conjugates of compound A. The signals of the mercapturic acids, 3,3,3-trifluoro-2-(fluoromethoxy)-propanoic acid and 3,3,3-trifluorolactic acid were visible after combining and concentrating the patient urines. CAMA-I and -II excretions in patients were completed after 24 h. 5. Since 19F-nuclear magnetic resonance is not sensitive enough, urinary mercapturic acids concentrations were quantified by gas chromatography-electron capture detection. CAMA-I and -II urinary concentrations were 2.3 ± 0.7 and 1.4 ± 0.4 mol mg−1 creatinine, respectively. Urinary excretion of CAMA-I showed a correlation with sevoflurane exposure, whereas CAMA-II did not. 6. The results show that 19F-nuclear magnetic resonance is a very selective and convenient technique to detect and quantify HFIP in non-concentrated human urine. 19F-nuclear magnetic resonance can also be used to monitor the oxidative biotransformation of sevoflurane in anaesthetized patients. Compound A-derived mercapturic acids and 3,3,3-trifluoro-2-(fluoromethoxy)-propanoic acid and 3,3,3-trifluorolactic acid, however, require more sensitive techniques such as gas chromatography-electron capture detection and/or gas chromatography-mass spectrometry for quantification.

Mercury intoxication and neuropathic pain

produce systemic side effects in susceptible patients (4). To limit this, many centers use atropine ointment rather than drops for children. The large molecules of the ointment are not easily removed by the lacrimal drainage system by blinking thus producing lower systemic concentrations of atropine compared with the solution (5) . Moreover, atropine in ointment form is retained in the conjunctival sac for a longer time thereby allowing effective cycloplegia with minimal side effects (6). Lastly, in our institute, the use of atropine ointment for cycloplegia is generally reserved for young children (<5 years) who either have accommodative esotropia or are refractory to other cycloplegic agents. Accurate measurement of hyperopia is necessary to correct accommodative esotropia. This requires maximum cycloplegia which is most reliably achieved with the 3 day routine of atropinization (7). Till the availability of a safer and more potent cycloplegic agent, ocular atropine will continue to be used and our intention was to make the anesthesiologist aware of the possible adverse effects of ocular atropine. Vimi Rewari Anjan Trikha Department of Anaesthesiology and Intensive care, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110029 (email: vimirewari@gmail.com)

Effect of Body Temperature on Peripheral Venous Pressure Measurements and Its Agreement with Central Venous Pressure in Neurosurgical Patients

Previous studies suggest a correlation of central venous pressure (CVP) with peripheral venous pressure (PVP) in different clinical settings. The effect of body temperature on PVP and its agreement with CVP in patients under general anesthesia are investigated in this study. Fifteen American Society of Anesthesiologists I-II patients undergoing elective craniotomy were included in the study. CVP, PVP, and core (Tc) and peripheral (Tp) temperatures were monitored throughout the study. A total of 950 simultaneous measurements of CVP, PVP, Tc, and Tp from 15 subjects were recorded at 5-minute intervals. The measurements were divided into low- and high-Tc and -Tp groups by medians as cutoff points. Bland-Altman assessment for agreement was used for CVP and PVP in all groups. PVP measurements were within range of ±2 mm Hg of CVP values in 94% of the measurements. Considering all measurements, mean bias was 0.064 mm Hg (95% confidence interval −0.018-0.146). Corrected bias for repeated measurements was 0.173 ± 3.567 mm Hg (mean ± SDcorrected). All of the measurements were within mean ± 2 SD of bias, which means that PVP and CVP are interchangeable in our setting. As all the measurements were within 1 SD of bias when Tc was ≥35.8 °C, even a better agreement of PVP and CVP was evident. The effect of peripheral hypothermia was not as prominent as core hypothermia. PVP measurement may be a noninvasive alternative for estimating CVP. Body temperature affects the agreement of CVP and PVP, which deteriorates at lower temperatures.

Bolus ketamine does not decrease hyperalgesia after remifentanil infusion

Abstract Background and aim: Several animal and human studies have proposed that acute tolerance to opioids might be manipulated by NMDA receptor antagonists. This study was designed to test the opioid-induced hyperalgesia produced by remifentanil, and to evaluate the effect of ketamine under these conditions. Methods: Forty-seven ASA 1-2 patients undergoing lumbar disc operation were randomly assigned into 3 anaesthetic regimens. The patients were not premedicated. After standard anaesthesia induction with propofol and vecuronium, group R and group K patients received a remifentanil infusion of 0.1 μg kg−1 min−1. Group K also received 0.5 mg kg−1 ketamine bolus before remifentanil infusion. Group S was the control group and equal volume of saline instead of remifentanil was infused throughout the operation. Groups R and S also received a bolus of the same volume of saline instead of ketamine by an anaesthesiologist blinded to the study. After the surgery under desflurane anaesthesia, patient-controlled a...

The addition of metamizole to morphine and paracetamol improves early postoperative analgesia and patient satisfaction after lumbar disc surgery.

AIM Combined analgesic regimens produce sufficient analgesia by additive or synergistic effects, and reduce the total dose of analgesics and minimise adverse effects. We investigated the metamizole, paracetamol and morphine combination with respect to postoperative pain treatment in lumbar disc surgery. MATERIAL AND METHODS After Ethics Committee approval and informed consent, 63 patients were allocated to three treatment groups; as Group paracetamol: paracetamol (1 g), Group paracetamol-metamizole: paracetamol (1 g) and metamizole (1 g), and Group placebo: no analgesic. All the patients received intravenous (i.v.) morphine with a patient-controlled analgesia device (PCA) as the rescue analgesic. Pain was assessed by the numerical pain rating scale (NRS, 0-3). Total morphine consumption at 24 hours, patient satisfaction and side effects were investigated. RESULTS NRS of Group paracetamol-metamizole was low at 15th min, 30th min and 1st hour, and the difference reached statistical significance at 30th min (p=0.033). Patient satisfaction at the same measurement times was high in this group. Total morphine consumption and side effects were not statistically different between the three groups. CONCLUSION Addition of metamizole to paracetamol along with iv morphine PCA offers an advantage over single iv morphine PCA and paracetamol, with respect to early postoperative pain treatment and patient satisfaction.

Urinary lipid and protein oxidation products upon halothane, isoflurane, or sevoflurane anesthesia in humans: potential biomarkers for a subclinical nephrotoxicity

Objective: To investigate whether lipid and protein oxidation products are elevated and correlated with routine clinical markers of hepatic and renal function in patients anesthetized with halothane, isoflurane, or sevoflurane. Methods: Urine and blood samples were collected from patient groups. Excretion of aldehydes, acetone, and o,o’-dityrosine was measured before and after anesthesia. Blood samples were analysed for clinical markers. Results: Urinary concentrations of aldehydes, acetone, o,o’-dityrosine and glucose were significantly increased after anesthesia in halothane and sevoflurane groups earlier than clinical markers. Significant correlations were found in sevoflurane group. Conclusion: Lipid and protein oxidation contributes to subclinical sevoflurane nephrotoxicity. Oxidation products may serve as early biomarkers.