Intravenous lidocaine infusion reduces bispectral index-guided requirements of propofol only during surgical stimulation.

BACKGROUND: I.V. lidocaine reduces volatile anaesthetics requirements during surgery. We hypothesized that lidocaine would also reduce propofol requirements during i.v. anaesthesia. METHODS: A randomized controlled study of 40 patients tested the effect of i.v. lidocaine (1.5 mg kg(-1) then 2 mg kg(-1) h(-1)) on propofol requirements. Anaesthesia was maintained with remifentanil and propofol target-controlled infusions (TCI) to keep the bispectral index (BIS) around 50. Effect-site concentrations of propofol and remifentanil and BIS values were recorded before and after skin incision. Data were analysed using anova and mixed effects analysis with NONMEM. Two dose-response studies were then performed with and without surgical stimulation. Propofol TCI titrated to obtain a BIS around 50 was kept constant. Then patients were randomized into four groups: A, saline; B, 0.75 mg kg(-1) bolus then infusion 1 mg kg(-1) h(-1); C, 1.5 mg kg(-1) bolus and infusion 2 mg kg(-1) h(-1); and D, 3 mg kg(-1) bolus and infusion 4 mg kg(-1) h(-1). Lidocaine administration coincided with skin incision. BIS values and haemodynamic variables were recorded. Data were analysed using linear regression and two-way anova. RESULTS: Lidocaine decreased propofol requirements (P<0.05) only during surgery. In the absence of surgical stimulation, lidocaine did not affect BIS nor haemodynamic variables, whereas it reduced BIS increase (P=0.036) and haemodynamic response (P=0.006) secondary to surgery. CONCLUSIONS: The sparing effect of lidocaine on anaesthetic requirements seems to be mediated by an anti-nociceptive action.

Norepinephrine and ephedrine do not counteract the increase in cutaneous microcirculation induced by spinal anaesthesia.

BACKGROUND: Neuraxial anaesthesia improves tissue perfusion and tissue oxygen tension. Vasodilation induced by this technique may result in hypotension requiring the administration of vasoactive drugs. The use of peripheral vasoconstrictors might counteract the improved tissue perfusion and its potentially beneficial effects. We therefore investigated the effect of i.v. norepinephrine and ephedrine on skin perfusion using laser-Doppler flowmetry (LDF) in patients during spinal anaesthesia. METHODS: Skin blood flow expressed in perfusion units (PU) provided by LDF was measured simultaneously at the foot and the manubrium levels in 44 patients during spinal anaesthesia with a sensory level below T5. Norepinephrine infusion was then titrated to normalize mean arterial pressure (MAP) in 23 patients (Group NOR). Ephedrine (max. 10 mg) was administered in 21 patients (Group EPH). Changes in relative PU were compared between the two sites of measurements in each group during drug administration. The same doses of norepinephrine were assessed in 11 normal volunteers to assure comparable vasoreactivity at the foot and manubrium levels. RESULTS: Spinal anaesthesia resulted in a 10% decrease in MAP (P<0.001), an increase in relative PU values at the foot level (P<0.001), and a decrease at the sternum level (P<0.05). Norepinephrine and ephedrine produced a significant increase in relative PU values at the foot level when compared with the sternum level (NOR: P=0.02; EPH: P=0.0035). In volunteers, norepinephrine decreased cutaneous perfusion similarly at the manubrium and foot levels. CONCLUSIONS: Improved skin perfusion induced by spinal anaesthesia was not counteracted by the use of norepinephrine or ephedrine.

Cerebral subarachnoid blood migration consecutive to a lumbar haematoma after spinal anaesthesia.

We report the case of a woman who received spinal anaesthesia for peripheral vascular surgery of the lower limbs and subsequently developed a spinal subarachnoid haematoma. Interestingly, low back pain was the only symptom of this spinal subarachnoid haemorrhage. During the following days, blood migrated from the spinal haematoma towards the cerebral subarachnoid spaces. The patient presented with stupor, nausea and vomiting that resolved within 2 weeks with conservative treatment.

Acute rehabilitation program after laparoscopic colectomy using intravenous lidocaine.

BACKGROUND: The concept of postoperative acute rehabilitation was introduced to accelerate postoperative recovery and improve outcome. We investigated whether intravenous lidocaine infusion, which decreases postoperative pain and speeds the return of bowel function, can be used instead of epidural analgesia in an acute rehabilitation protocol for patients undergoing laparoscopic colectomy. METHODS: Twenty eight consecutive patients scheduled for laparoscopic colectomy were prospectively included in this case series study. Segmental colectomy was performed only for benign pathology. Intraoperative opioid use was restricted. After a bolus injection of lidocaine 1.5 mg x kg(-1), an infusion (2 mg x kg(-1) x h(-1), i.v.) was started before pneumoperitoneum. Balanced analgesia was used to reduce postoperative opioid consumption. Patients were allowed to drink 6 h postoperatively. The day after surgery, patients were allowed to eat a normal breakfast. Enforced mobilisation and ambulation were required from the patients. Our goal was to discharge patients within 3 days after surgery. Postoperative pain was measured. Time to first flatus, defecation, and hospital discharge were recorded. RESULTS: Mean postoperative pain at rest and mobilisation remained below 30 mm on a 100 mm visual analogue scale. Time to first flatus, defecation, and hospital discharge were 29 +/- 13 h, 38 +/- 13 h, and 3.0 +/- 1.0 days, respectively. CONCLUSION: Acute rehabilitation after laparoscopic colectomy using i.v. lidocaine gives similar outcomes to those reported using epidural analgesia.

Supplemental oxygen does not reduce postoperative nausea and vomiting after thyroidectomy.

BACKGROUND: Supplemental intra-operative oxygen 80% halves the incidence of nausea and vomiting after open and laparoscopic abdominal surgery, perhaps by ameliorating intestinal ischaemia associated with abdominal surgery. It is unlikely that thyroid surgery compromises intestinal perfusion. We therefore tested the hypothesis that supplemental perioperative oxygen does not reduce the risk of postoperative nausea and vomiting (PONV) after thyroidectomy. METHODS: One hundred and fifty patients undergoing thyroidectomy were given sevoflurane anaesthesia. After induction, patients were randomly assigned to the following treatments: (i). 30% oxygen, (ii). 80% oxygen, or (iii). 30% oxygen with droperidol 0.625 mg. RESULTS: The overall incidence of nausea during the first 24 h after surgery was 48% in the patients given oxygen 30%, 46% in those given oxygen 80%, and 22% in those given droperidol (P=0.004). There were no significant differences between the oxygen 30% and 80% groups in incidence or severity of PONV, the need for rescue antiemetics, or patient satisfaction. Droperidol significantly shortened the time to first meal. CONCLUSIONS: Supplemental oxygen was ineffective in preventing nausea and vomiting after thyroidectomy, but droperidol reduced the incidence.

Oxidation of tetrahydrobiopterin by peroxynitrite or oxoferryl species occurs by a radical pathway.

The molecular mechanisms of tetrahydrobiopterin (BH4) oxidation by peroxynitrite (ONOO-) was studied using ultra-weak chemiluminescence, electron paramagnetic resonance (EPR) and UV-visible diode-array spectrophotometry, and compared to BH4 oxidation by oxoferryl species produced by the myoglobin/hydrogen peroxide (Mb/H2O2) system. The oxidation of BH4 by ONOO- produced a weak chemiluminescence, which was altered by addition of 50 mM of the spin trap alpha-(4-pyridyl-1-oxide)-N-tert butylnitrone (POBN). EPR spin trapping demonstrated that the reaction occurred at least in part by a radical pathway. A mixture of two spectra composed by an intense six-line spectrum and a fleeting weak nine-line one was observed when using ONOO-. Mb/H2O2 produced a short-living light emission that was suppressed by the addition of BH4. Simultaneous addition of POBN, BH4 and Mb/H2O2 produced the same six-line EPR spectrum, with a signal intensity depending on BH4 concentration. Spectrophotometric studies confirmed the rapid disappearance of the characteristic peak of ONOO- (302 nm) as well as substantial modifications of the initial BH4 spectrum with both oxidant systems. These data demonstrated that BH4 oxidation, either by ONOO- or by Mb/H2O2, occurred with the production of activated species and by radical pathways.

In vitro study of the antioxidant properties of nimesulide and 4-OH nimesulide: effects on HRP- and luminol-dependent chemiluminescence produced by human chondrocytes.

OBJECTIVES: Reactive oxygen species (ROS) are now recognized to play an important role in the pathogenesis of rheumatic diseases and constitute an interesting therapeutic target for drugs. This in vitro study was designed to evaluate the antioxidant properties of nimesulide (NIM), a nonsteroidal antiinflammatory drug of the sulfonanilide class, and its main metabolite 4-OH nimesulide (4-OHNIM). METHODS: The scavenging effects of NIM and 4-OH NIM on hydroxyl radical ((.)OH) and superoxide anions (O(minusd)(2)) were investigated by electron spin resonance (ESR), using 5, 5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. The quenching properties of these drugs on hypochlorite anion was studied by luminol enhanced chemiluminescence. Finally, the effects of NIM and 4-OHNIM on the reactive oxygen species production by human articular chondrocytes were recorded by HRP and luminol-enhanced chemiluminescence. RESULTS: By this method it has been demonstrated that NIM and 4-OHNIM, at concentrations ranging from 10 to 100 microM, are potent scavengers of(.)OH whereas only 4-OHNIM was capable to scavenge O(minusd)(2). Chemiluminescence generated by HOCl was also significantly and dose-dependently inhibited by both NIM and 4-OHNIM. Nevertheless, at each concentration tested, the inhibitory effect of 4-OHNIM was significantly more marked, even at the highest concentration (100 microM). Furthermore, when chondrocytes were pre-incubated for 48-96 h with NIM or 4-OHNIM, the luminol- and HRP-dependent CL produced by the cells was significantly inhibited in a dose-dependent manner. CONCLUSIONS: NIM and 4-OHNIM may protect cartilage against oxidative stress, not only by scavenging ROS but also by inhibiting their production by chondrocytes.

Randomized trial of diaspirin cross-linked hemoglobin solution as an alternative to blood transfusion after cardiac surgery. The DCLHb Cardiac Surgery Trial Collaborative Group.

BACKGROUND: Risks associated with transfusion of allogeneic blood have prompted development of methods to avoid or reduce blood transfusions. New oxygen-carrying compounds such as diaspirin cross-linked hemoglobin (DCLHb) could enable more patients to avoid allogeneic blood transfusion. METHODS: The efficacy, safety, hemodynamic effects, and plasma persistence of DCLHb were investigated in a randomized, active-control, single-blind, multicenter study in post-cardiac bypass surgery patients. Of 1,956 screened patients, 209 were determined to require a blood transfusion and met the inclusion criteria during the 24-h post-cardiac bypass period. These patients were randomized to receive up to three 250-ml infusions of DCLHb (n = 104) or three units of packed erythrocytes (pRBCs; n = 105). Further transfusions of pRBCs or whole blood were permitted, if indicated. Primary efficacy end points were the avoidance of blood transfusion through hospital discharge or 7 days postsurgery, whichever came first, and a reduction in the number of units of pRBCs transfused during this same time period. Various laboratory, physiologic, and hemodynamic parameters were monitored to define the safety and pharmacologic effect of DCLHb in this patient population. RESULTS: During the period from the end of cardiopulmonary bypass surgery through postoperative day 7 or hospital discharge, 20 of 104 (19%) DCLHb recipients did not receive a transfusion of pRBCs compared with 100% of control patients (P < 0.05). The overall number of pRBCs administered during the 7-day postoperative period was not significantly different. Mortality was similar between the DCLHb (6 of 104 patients) and the control (8 of 105 patients) groups. Hypertension, jaundice/hyperbilirubinemia, increased serum glutamic oxalo-acetic transaminase, abnormal urine, and hematuria were reported more frequently in the DCLHb group, and there was one case of renal failure in each group. The hemodynamic effects of DCLHb included a consistent and slightly greater increase in systemic and pulmonary vascular resistance with associated increases in systemic and pulmonary arterial pressures compared with pRBC. Cardiac output values decreased more in the DCLHb group patients after the first administration than the control group patients. At 24 h postinfusion, the plasma hemoglobin level was less than one half the maximal level for any amount of DCLHb infused. CONCLUSIONS: Administration of DCLHb allowed a significant number (19%) of cardiac surgery patients to avoid exposure to erythrocytes postoperatively.

Hemodynamic changes and catecholamine release during laparoscopic adrenalectomy for pheochromocytoma.

UNLABELLED: We investigated hemodynamics and plasma catecholamine concentrations in eight consecutive patients undergoing laparoscopic adrenalectomy for suspected pheochromocytoma. The same anesthesia protocol was used in all patients: a continuous infusion of sufentanil 0.5 microg x kg(-1) x h(-1) and isoflurane 0.4% (end-tidal) in 50% N2O/O2. Systolic arterial pressure was maintained between 120 and 160 mm Hg by adjusting an infusion of nicardipine, a calcium-channel blocker, while tachycardia (>100 bpm) was treated by 1-mg boluses of atenolol. Hemodynamics (thermodilution technique) and plasma catecholamine concentrations were measured before surgery, after the induction of anesthesia, after turning the patient to the lateral position, during pneumoperitoneum, during tumor manipulation, after adrenalectomy, and at the end of surgery. Two events resulted in significant catecholamine release: creation of the pneumoperitoneum and adrenal gland manipulation. As a consequence, a twofold increase in cardiac output was recorded. Adjustments of nicardipine infusion (2-6 microg x kg(-1) x min(-1)) minimized changes in mean arterial pressure. Beta-adrenergic blockade was necessary in six patients. In conclusion, laparoscopic adrenalectomy for pheochromocytoma results in marked catecholamine release during pneumoperitoneum and tumor manipulation. Titration of a nicardipine infusion allowed easy and quick control of the hemodynamic aberrancies related to these processes. IMPLICATIONS: Pneumoperitoneum during laparoscopy, now used for adrenalectomy, may complicate anesthetic management of patients with pheochromocytoma. In this study, laparoscopic adrenalectomy was associated with catecholamine release during the creation of pneumoperitoneum and tumor manipulation. Adjustments of a nicardipine infusion readily attenuated the subsequent hemodynamic aberrancies.

Hemodynamic changes induced by laparoscopy and their endocrine correlates: effects of clonidine.

OBJECTIVES: We investigated endocrine correlates of the hemodynamic changes induced by carbon dioxide pneumoperitoneum (PNO). We then studied whether clonidine might modulate the hemodynamic changes induced by PNO by reducing release of catecholamines and vasopressin. BACKGROUND: Both mechanical and neurohumoral factors contribute to the hemodynamic changes induced by carbon dioxide PNO. Several mediators have been proposed, but no study has correlated hemodynamic changes with changes in levels of these potential mediators. METHODS: We conducted two studies, each including 20 healthy patients scheduled for elective laparoscopic cholecystectomy. In the first study serial measurements of hemodynamics (thermodilution technique) were done during laparoscopy and after exsufflation. Plasma concentrations of cortisol, catecholamines, vasopressin, renin, endothelin and prostaglandins were measured at the same time points. In the second study patients were randomly allocated to receive 8 microg/kg clonidine infused over 1 h or placebo before PNO. Hemodynamics and plasma levels of cortisol, catecholamines and vasopressin were measured during PNO and after exsufflation. RESULTS: Peritoneal insufflation resulted in a significant reduction of cardiac output (18+/-4%) and increases in mean arterial pressure (39+/-8%) and systemic (70+/-12%) and pulmonary (98+/-18%) vascular resistances. Laparoscopy resulted in progressive and significant increases in plasma concentrations of cortisol, epinephrine, norepinephrine and renin. Vasopressin plasma concentrations markedly increased immediately after the beginning of PNO (before PNO 6+/-4 pg/ml; during PNO 129+/-42 pg/ml; p < 0.05). The profile of vasopressin release paralleled the time course of changes in systemic vascular resistance. Prostaglandins and endothelin did not change significantly. Clonidine significantly reduced mean arterial pressure, heart rate and the increase in systemic vascular resistance. Clonidine also significantly reduced catecholamine concentrations but did not alter vasopressin and cortisol plasma concentrations. CONCLUSIONS: Vasopressin and catecholamines probably mediate the increase in systemic vascular resistance observed during PNO. Clonidine before PNO reduces catecholamine release and attenuates hemodynamic changes during laparoscopy.

Pulmonary function and pain after gastroplasty performed via laparotomy or laparoscopy in morbidly obese patients.

We have compared severely obese patients (body mass index > 35 kg m-2) undergoing laparoscopic or open gastroplasty (n = 15 in each group) to determine if laparoscopy results in any benefit in the obese. Postoperative pain, measured on a 100-mm visual analogue scale, and opioid consumption were recorded during the first two days after operation. Tests of pulmonary function were performed and SpO2 was measured 4 h after surgery and on days 1, 2 and 3 after operation. Pain at rest was similar in the two groups, but in the laparoscopy group, requirements for postoperative opioid were 50% less (P < 0.05). Pain intensity during mobilization and on coughing was significantly less after laparoscopy (differences between mean pain scores in both groups ranged from 20 to 32 mm during mobilization and from 32 to 34 mm during coughing). Forced vital capacity, forced expiratory volume in 1 s and peak expiratory flow rate were reduced significantly less after laparoscopic gastroplasty than after open gastroplasty (on day 1 forced vital capacity was reduced by 50% compared with 64%, forced expiratory volume in 1 s was reduced by 50% compared with 66% and peak expiratory flow rate by 45% compared with 60%). SpO2 values were significantly greater in the laparoscopy group (day 1: mean 95 (SD 2)% vs 91 (5)%; day 3: 97 (1)% vs 94 (3)%). This study suggests that the beneficial effects observed after laparoscopic gastroplasty in morbidly obese patients were similar to those reported after laparoscopic cholecystectomy in non-obese patients.

Emergence from target-controlled anesthesia with propofol and sufentanil in patients undergoing intracranial surgery.

The study was designed to characterise the emergence from target-controlled anesthesia assessed by the recovery of spontaneous breathing, eye opening to command, and extubation in 18 adult patients undergoing intracranial surgery. Total intravenous anesthesia was induced and maintained with propofol and sufentanil. Target plasma concentration of propofol ranged between 3.0 and 5.5 micrograms.ml-1 and infusion was stopped after head dressing. The initial target plasma sufentanil concentration of 0.50 ng.ml-1 was decreased to 0.15 ng.ml-1 after craniotomy; sufentanil infusion was discontinued at the dura closure. The time from the end of surgery (head dressing) to recovery of spontaneous breathing was 8.3 +/- 6.5 min, and the time to eye opening and extubation was 14.7 +/- 10.0 min. At the end of surgery, the calculated plasma propofol concentration was 3.42 +/- 0.26 micrograms.ml-1. It significantly decreased to 2.11 +/- 0.51 micrograms.ml-1 at recovery of spontaneous breathing and to 1.81 +/- 0.41 micrograms.ml-1 at eye opening and extubation. The calculated plasma sufentanil concentration was 0.108 +/- 0.019 ng.ml-1 at the end of surgery but did not change significantly between recovery of spontaneous breathing (0.089 +/- 0.013 ng.ml-1), eye opening and extubation (0.087 +/- 0.013 ng.ml-1). The calculated plasma propofol concentrations recorded at emergence were not correlated with patient age, total dose of propofol, and duration of infusion; corresponding calculated sufentanil concentrations were not correlated with age and total dose of sufentanil. An inverse relationship (p < 0.05) was found between the duration of sufentanil infusion and the calculated sufentanil concentrations at emergence. No correlation was observed between calculated concentrations of propofol and sufentanil at emergence.

Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on the postoperative pulmonary restrictive syndrome in obese patients undergoing gastroplasty.

STUDY OBJECTIVE: Upper abdominal surgery results in a postoperative restrictive pulmonary syndrome. Bi-level positive airway pressure (BiPAP System; Respironics Inc; Murrysville, Pa), which combines pressure support ventilation and positive end-expiratory pressure via a nasal mask, could allow alveolar recruitment during inspiration and prevent expiratory alveolar collapse, and therefore limit the postoperative pulmonary restrictive syndrome. This study investigated the effect of BiPAP on postoperative pulmonary function in obese patients after gastroplasty. DESIGN: Prospective controlled randomized study. SETTING: GI surgical ward in a university hospital. PATIENTS: Thirty-three morbidly obese patients scheduled for gastroplasty were studied. INTERVENTION: The patients were assigned to one of three techniques of ventilatory support during the first 24 h postoperatively: O2 via a face mask, BiPAP System 8/4, with inspiratory and expiratory positive airway pressure set at 8 and 4 cm H2O, respectively, or BiPAP System 12/4 set at 12 and 4 cm H2O. Pulmonary function (FVC, FEV1, and peak expiratory flow rate [PEFR]) were measured the day before surgery, 24 h after surgery, and on days 2 and 3. Oxygen saturation by pulse oximeter (SpO2) was also recorded during room air breathing. RESULTS: Three patients were excluded. After surgery, FVC, FEV1, PEFR, and SpO2 significantly decreased in the three groups. On day 1, FVC and FEV1 were significantly improved in the group BiPAP System 12/4, as compared with no BiPAP; SpO2 was also significantly improved. After removal of BiPAP System 12/4, these benefits were maintained, allowing faster recovery of pulmonary function. No significant effects were observed on PEFR. BiPAP System 8/4 had no significant effect on the postoperative pulmonary restrictive syndrome. CONCLUSION: Prophylactic use of BiPAP System 12/4 during the first 24 h postoperatively significantly reduces pulmonary dysfunction after gastroplasty in obese patients and accelerates reestablishment of preoperative pulmonary function.

Pneumothorax during laparoscopic fundoplication: diagnosis and treatment with positive end-expiratory pressure.

Pneumothorax can develop during laparoscopy, particularly during laparoscopic fundoplication, since the left parietal pleura is exposed and can be torn during dissection in the diaphragmatic hiatus. Such an event will result in specific pathophysiologic changes, since CO2, under pressure in the abdominal cavity, will pass into the pleural space. The aim of this study was to document the pathophysiologic changes induced by pneumothorax, and to evaluate the benefit of positive end-expiratory pressure (PEEP) to treat pneumothorax. Forty-six ASA physical status I and II patients scheduled for laparoscopic fundoplication were monitored extensively; heart rate, mean arterial pressure, end-tidal CO2 (PETCO2), oxygen saturation of hemoglobin (Spo2), minute ventilation, tidal volume, dynamic total lung thorax compliance, and airway pressures were recorded. In 25 patients, oxygen uptake, CO2 elimination and arterial blood gases were also measured. Pneumothorax was diagnosed in seven patients. It resulted in the following pathophysiologic changes: decrease in total lung thorax compliance, increase in airway pressures, and increase in CO2 absorption. Consequently, PACO2 and PETCO2 also increased. Spo2, however, remained normal. The use of PEEP largely corrected these respiratory changes. None of these pneumothoraces required drainage. These data suggest that pneumothorax is common during laparoscopic fundoplication. Early diagnosis is possible by simultaneous monitoring of PETCO2, total lung thorax compliance, and airway pressures. Finally, treatment with PEEP provides an alternative to chest tube placement when pneumothorax is secondary to passage of peritoneal CO2 into the interpleural space.

Hemodynamic changes during laparoscopic cholecystectomy.

Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.