Physiological and Clinical Impact of Repeated Inhaled Oxygen Variation on Erythropoietin Levels in Patients After Surgery.

The "Normobaric Oxygen Paradox" (NOP) is a physiologic mechanism that induces an increase of endogenous erythropoietin (EPO) production by creating a state of relative hypoxia in subjects previously exposed to hyperoxia, followed by a rapid return to normoxia. Oxygen exposure duration and inspired oxygen fraction required to observe a significant increase in EPO or hemoglobin are not clearly defined. Consequently, we here study the effect of one model of relative hypoxia on EPO, reticulocytes and hemoglobin stimulation in patients after surgery. Patients were prospectively randomized in two groups. The O2 group (n = 10) received 100% oxygen for 1 h per day for eight consecutive days, via a non-rebreathing mask. The control group (n = 12) received no oxygen variation. Serum EPO, hemoglobin and reticulocyte count were measured on admission and postoperatively on days seven and nine. Percentage EPO at day nine with respect to the baseline value was significantly elevated within the groups [O2 group: 323.7 (SD ± 139.0); control group: 365.6 (SD± 162.0)] but not between them. No significant difference was found between the groups in terms of reticulocytes count and hemoglobin. Our NOP model showed no difference on EPO increase between the two groups. However, both groups expressed separately significant EPO elevation.

Potential Benefit of Intra-operative Administration of Ketorolac on Breast Cancer Recurrence According to the Patient's Body Mass Index.

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are currently used in some countries as analgesics in primary cancer surgery. Retrospective studies suggest that NSAIDs could reduce breast cancer recurrences. Because NSAIDs also act on biological mechanisms present in patients with increased adiposity, we aimed at assessing whether the intra-operative administration of ketorolac or diclofenac would be associated with a reduction of recurrence in patients with elevated body mass index (BMI). Methods: We considered two institutional retrospective series of 827 and 1007 patients evaluating the administration of ketorolac (n = 529 with, n = 298 without) or diclofenac (n = 787 with, n = 220 without). The BMI subgroups were defined as less than 25 kg/m2 (lean) and 25 or more kg/m2 (overweight and obese). Cumulative incidence estimation of distant metastases as well as Fine-Gray and Dixon-Simon models was used. These analyses were adjusted for clinico-pathological variables. All statistical tests were two-sided. Results: The administration of ketorolac was statistically significantly associated with decreased incidence of distant recurrences (adjusted hazard ratio [aHR]= 0.59, 95% confidence interval [CI] = 0.37 to 0.96, P = .03). In particular, the association was evident in the high-body mass index (BMI) group of patients (aHR = 0.55, 95% CI = 0.31 to 0.96, P = .04). The administration of diclofenac was not statistically significantly associated with decreased incidence of distant recurrences, either in the global population or in the BMI subgroups. Conclusions: These results show that the intra-operative administration of ketorolac, but not diclofenac, is statistically significantly associated with a reduction of distant recurrences in patients with increased BMI. Altogether, this study points to a potentially important repositioning of ketorolac in the intra-operative treatment of patients with elevated BMI that, if prospectively validated, might be as impactful as and cheaper than adjuvant systemic anticancer therapies.

Single-access transumbilical laparoscopic appendectomy and cholecystectomy using new curved reusable instruments: a pilot feasibility study.

BACKGROUND: The umbilicus can be considered as the embryological opening for single-access laparoscopic procedures. We report on single-access transumbilical laparoscopic appendectomy (SATLA) and cholecystectomy (SATLC), performed using new curved reusable instruments. PATIENTS AND METHODS: A retrospective review of a prospectively maintained database of 30 patients who underwent SATLA and 20 patients who underwent SATLC between May and November 2009 was undertaken. All procedures were performed with an 11-mm nondisposable trocar for the scope, and curved reusable instruments (Karl Storz-Endoskope, Tuttlingen, Germany) placed transumbilically without trocars. Outcome measures were conversion to standard laparoscopy, operative time, scar length, complications, hospital stay, and use of pain medication. RESULTS: All SATLA patients had acute appendicitis, and SATLC patients had symptomatic gallstones (15), chronic cholecystitis (3), and acute cholecystitis (2). No extraumbilical trocars were necessary. Mean total operative times were 57.3 ± 15.9 min (SATLA) and 73.9 ± 20.1 min (SATLC). Mean laparoscopic times were 39 ± 13.1 min (SATLA) and 57.5 ± 18.9 min (SATLC). Mean scar lengths were 14.8 ± 2.2 mm (SATLA) and 15.8 ± 2.3 mm (SATLC). Five SATLA patients and one SATLC patient developed postoperative complications. Mean hospital stay was 2.9 ± 1.3 days for SATLA patients and 1.8 ± 0.8 days for SATLC patients. Pain medication used was minimal. At the minimum follow-up of 3 months no late complications were registered. CONCLUSIONS: SATLA and SATLC can be performed safely using curved reusable instruments, which helps avoid the conflict between the surgeon's hands or between the instruments' tips and allows the surgeon to operate in an ergonomic position. The reusable instruments kept the cost similar to that of classic laparoscopy.

Ultrasound-guided block of the brachial plexus at the humeral canal.

PURPOSE: Conduction block of the brachial plexus block at the humeral canal, as described by Dupre, has certain clinical indications. The aim of this preliminary study was to assess the feasibility of this technique under ultrasound guidance. METHODS: After ultrasound evaluation of the brachial plexus at the humeral canal in 61 adult volunteers, we performed ultrasound-guided blocks in another 20 adult patients. A linear 38 mm probe, 13-6 MHz, and a 50-mm insulated block needle were used to guide injection of lidocaine 1.5% with epinephrine. RESULTS: Ulnar and median nerves are superficial and located at similar depths. Ultrasound imaging showed the musculocutaneous nerve to be located dorsally. The radial nerve is dorsal to the plane of the musculocutaneous nerve. Relative to the brachial artery, the median nerve is situated between 12 and 1 o'clock in 66% of the cases. Relative to the basilic vein, the ulnar nerve is situated at 3 o'clock in 46% of the cases. The evaluated block sequence was radial, ulnar, musculocutaneous and median nerve; two points of puncture were mandatory, and 6.85 +/- 0.37 min were required to perform the blocks. Sensory onset times were similar for the four nerves. Injectate volume was lower for the musculocutaneous nerve compared to other nerves (P < 0.05). All 20 patients experienced complete sensory and motor blocks. CONCLUSION: We describe an approach to, and the feasibility of ultrasound-guided block of the brachial plexus at the humeral canal. Further study will be required to establish the effectiveness and the safety of this technique.

Desflurane Consumption During Automated Closed-circuit Delivery is Higher Than When a Conventional Anesthesia Machine is Used With a Simple Vaporizer-O2-N2O Fresh Gas Flow Sequence.

BACKGROUND: The Zeus® (Dräger, Lübeck, Germany), an automated closed-circuit anesthesia machine, uses high fresh gas flows (FGF) to wash-in the circuit and the lungs, and intermittently flushes the system to remove unwanted N2. We hypothesized this could increase desflurane consumption to such an extent that agent consumption might become higher than with a conventional anesthesia machine (Anesthesia Delivery Unit [ADU®], GE, Helsinki, Finland) used with a previously derived desflurane-O2-N2O administration schedule that allows early FGF reduction. METHODS: Thirty-four ASA PS I or II patients undergoing plastic, urologic, or gynecologic surgery received desflurane in O2/N2O. In the ADU group (n = 24), an initial 3 min high FGF of O2 and N2O (2 and 4 L.min-1, respectively) was used, followed by 0.3 L.min-1 O2 + 0.4 L.min-1 N2O. The desflurane vaporizer setting (FD) was 6.5% for the first 15 min, and 5.5% during the next 25 min. In the Zeus group (n = 10), the Zeus® was used in automated closed circuit anesthesia mode with a selected end-expired (FA) desflurane target of 4.6%, and O2/N2O as the carrier gases with a target inspired O2% of 30%. Desflurane FA and consumption during the first 40 min were compared using repeated measures one-way ANOVA. RESULTS: Age and weight did not differ between the groups (P > 0.05), but patients in the Zeus group were taller (P = 0.04). In the Zeus group, the desflurane FA was lower during the first 3 min (P < 0.05), identical at 4 min (P > 0.05), and slightly higher after 4 min (P < 0.05). Desflurane consumption was higher in the Zeus group at all times, a difference that persisted after correcting for the small difference in FA between the two groups. CONCLUSION: Agent consumption with an automated closed-circuit anesthesia machine is higher than with a conventional anesthesia machine when the latter is used with a specific vaporizer-FGF sequence. Agent consumption during automated delivery might be further reduced by optimizing the algorithm(s) that manages the initial FGF or by tolerating some N2 in the circuit to minimize the need for intermittent flushing.

Expression of adenosine A 2A receptors in the rat lumbar spinal cord and implications in the modulation of N-methyl-d-aspartate receptor currents.

BACKGROUND: The presence of A(2A) receptors in the dorsal horn of the spinal cord remains controversial. At this level, activation of N-methyl-d-aspartate (NMDA) receptors induces wind-up, which is clinically expressed as hyperalgesia. Inhibition of NMDA receptor currents after activation of A(2A) receptors has been shown in rat neostriatal neurons. In this study, we sought to establish the presence of adenosine A(2A) receptors in the lamina II of the rat lumbar dorsal horn neurons and investigated whether the activation of A(2A) receptors is able to modulate NMDA receptor currents. METHODS: Experiments were conducted in the rat lumbar spinal cord. The presence of adenosine A(2A) receptor transcripts inside the lumbar spinal cord is assessed with the reverse transcriptase polymerase chain reaction (RT-PCR) technique. Western blot experiments are performed at the same level. The RT-PCR technique is also performed specifically in the lamina II, and the presence of adenosine A(2A) receptor transcripts is assessed in neurons from the lamina II with the single-cell RT-PCR technique. The effect of adenosine A(2A) receptor activation on NMDA receptor currents is studied by the whole-cell configuration of the patch clamp technique. RESULTS: RT-PCR performed on the lumbar spinal cord revealed the presence of adenosine A(2A) receptor transcripts. Western blot experiments revealed the presence of A(2A) receptors in the lumbar spinal cord. RT-PCR performed on the substantia gelatinosa also revealed the presence of adenosine A(2A) receptor transcripts. Finally, single cell RT-PCR revealed the presence of adenosine A(2A) receptor transcripts in a sample of lamina II neurons. Patch clamp recordings showed an inhibition of NMDA currents during the application of a selective A(2A) agonist. CONCLUSIONS: These results demonstrate the presence of A(2A) receptor on neurons from the substantia gelatinosa of the rat lumbar dorsal horn and the inhibition of NMDA-induced currents by the application of a selective A(2A) receptor agonist. Therefore, A(2A) receptor ligands could modulate pain processing at the spinal cord level.

Effects of remifentanil on N-methyl-D-aspartate receptor: an electrophysiologic study in rat spinal cord.

BACKGROUND: Remifentanil hydrochloride contained in Ultiva (GlaxoSmithKline, Genval, Belgium) has been incriminated in difficult postoperative pain management, promotion of hyperalgesia, and direct N-methyl-D-aspartate (NMDA) receptor activation, but the involved mechanisms have remained unclear. In the current study, the authors investigated the effects of remifentanil hydrochloride, with and without its vehicle, glycine, on the activation of NMDA receptors and the modulation of NMDA-induced current on neurons inside the lamina II from the dorsal horn of rat spinal cord. METHODS: To test these effects, whole cell patch clamp recordings were conducted on acute rat lumbar spinal cord slices. Considering that both components of Ultiva (remifentanil hydrochloride and glycine) could be involved in NMDA receptor activation, experiments were performed first with remifentanil hydrochloride, second with glycine, and third with the two components within Ultiva. RESULTS: Remifentanil hydrochloride does not induce any current, whereas 3 mm glycine induced a current that was abolished by the specific NMDA glutamate site antagonist D-2-amino-5-phosphonovalerate. Ultiva (remifentanil hydrochloride with its vehicle, glycine) also evoked an inward current that was abolished by D-2-amino-5-phosphonovalerate and not significantly different from the glycine-induced current. Application of remifentanil hydrochloride potentiated the NMDA-induced inward current, and this potentiation was abolished by the mu-opioid receptor antagonist naloxone. CONCLUSION: These results show that remifentanil hydrochloride does not directly activate NMDA receptors. The NMDA current recorded after application of Ultiva is related to the presence of glycine. Induced NMDA current is potentiated by application of remifentanil hydrochloride through a pathway involving the mu-opioid receptor.

The anesthetic management of a case of tracheal necrosis.

A 63-yr-old female patient developed a tracheal necrosis after esophageal resection with gastric interposition. We report the anesthetic management of this patient undergoing tracheal repair focusing on an original airway management and ventilation strategy.

Sciatic nerve block in the popliteal fossa: description of a new medial approach.

PURPOSE: Sciatic nerve blocks through lateral approaches in the popliteal fossa have been proposed. We describe a new medial approach to the sciatic nerve at this level. METHODS: After an anatomical study on six cadavers, we performed sciatic nerve blocks on 20 patients. A 100-mm insulated needle and a nerve stimulator were used; 20 mL of lidocaine 1.5% with epinephrine were injected. RESULTS: Patients lied in the supine position, the thigh flexed, abducted and rotated externally (30 degrees in all directions). The leg was flexed at 130 degrees . In this position, above the adductor tubercle, a depression known as Jobert's fossa is palpated. Through this groove, a medial approach to the sciatic nerve at the level of the popliteal fossa is possible. The mean distance between the adductor tubercle and the puncture site is 6.18 cm (range 4-8 cm) and the mean distance between the skin and the sciatic nerve is 6.62 cm (range 4-9 cm). Mean time to perform the block was 100 sec (range 55-165 sec). Complete motor blockade was obtained after a mean time of 30 min (range 5-60 min) inside the common peroneal nerve area and 43 min (range 15-75 min) inside the tibial nerve area. Motor block was complete in 17 patients and sensory block in 18 patients. No vessel puncture was observed. CONCLUSION: We describe a new medial approach to the sciatic nerve in the popliteal fossa. More studies will be required to demonstrate the technique is effective and safe.

The radial nerve should be blocked before the ulnar nerve during a brachial plexus block at the humeral canal.

PURPOSE: The brachial plexus block through the humeral canal as described by Dupré is indicated in hand and forearm surgery. This block requires a multi-stimulation technique that emphasizes the necessity of a rigorous and safe technique. Nerve injury associated with regional anesthesia can entail significant morbidity for patients. Thus, we investigated the brachial block sequence in terms of unintended nerve stimulation as a surrogate of potential nerve injury. METHODS: Sixty patients were randomly allocated in two groups of 30. In Group I the radial nerve was blocked before the ulnar nerve. In Group II the ulnar nerve was blocked before the radial nerve. During the radial nerve approach we recorded, if present, an ulnar nerve response. During the ulnar nerve approach we recorded, if present, a radial nerve response. RESULTS: In Group I while looking for the radial nerve, in 50% of the cases, an ulnar motor response was recorded. In Group II while looking for the ulnar nerve, a radial motor response was recorded in 10% of the cases. CONCLUSION: Our results indicate that the radial nerve should be blocked before the ulnar nerve when performing a brachial plexus block at the humeral canal.