Comparison of Morphine and Remifentanil on the Duration of Weaning from Mechanical Ventilation / 대한구급학회지

No abstract available.

Comparison of Morphine and Remifentanil on the Duration of Weaning from Mechanical Ventilation / 대한중환자의학회지

No abstract available.

Safety and immunogenicity of recombinant rabies virus (ERAGS) in mice and raccoon dogs

PURPOSE: The development of a genetically modified live rabies vaccine applicable to wild raccoon dogs is necessary for the eradication of rabies in Korea. Thus, we constructed a recombinant rabies virus (RABV) called the ERAGS strain, using a reverse genetic system and evaluated its safety and efficacy in mice and its safety and immunogenicity in raccoon dogs. MATERIALS AND METHODS: ERAGS, which has Asn194Ser and Arg333Glu substitutions in the glycoprotein, was constructed using site-directed mutagenesis. Mice were inoculated with the ERAGS strain (either 10(5.0) or 10(7.0) FAID(50)/mL) via intramuscular (IM) or intracranial injections and then challenged with a virulent RABV. Raccoon dogs were administered the ERAGS strain (10(8.0) FAID(50)/mL) either orally or via the IM route and the immunogenicity of the strain was evaluated using fluorescent antibody virus neutralization tests. RESULTS: The ERAGS strain inoculated into murine neuroblastoma cells reached 10(7.8) FAID(50)/mL at 96-hour post-inoculation. The virus was not pathogenic and induced complete protection from virulent RABV in immunized 4- and 6-week-old mice. Korean raccoon dogs immunized with the ERAGS strain via IM or oral route were also safe from the virus and developed high titer levels (26.4-32.8 IU/mL) of virus-neutralizing antibody (VNA) at 4 weeks post-inoculation. CONCLUSION: The ERAGS RABV strain was effectively protective against rabies in mice and produced a high VNA titer in raccoon dogs.

A recombinant rabies virus (ERAGS) for use in a bait vaccine for swine

PURPOSE: Rabies viruses (RABV) circulating worldwide in various carnivores occasionally cause fatal encephalitis in swine. In this study, the safety and immunogenicity of a recombinant rabies virus, the ERAGS strain constructed with a reverse genetics system, was evaluated in domestic pigs. MATERIALS AND METHODS: Growing pigs were administered 1 mL (108.0 FAID50/mL) of the ERAGS strain via intramuscular (IM) or oral routes and were observed for 4 weeks' post-inoculation. Three sows were also inoculated with 1 mL of the ERAGS strain via the IM route. The safety and immunogenicity in swine were evaluated using daily observation and a virus-neutralizing assay (VNA). Fluorescent antibody tests (FAT) for the RABV antigen and reverse transcriptase-polymerase chain reaction (RT-PCR) assays for the detection of the nucleocapsid (N) gene of RABV were conducted with brain tissues from the sows after necropsy. RESULTS: The growing pigs and sows administered the ERAGS strain did not exhibit any clinical sign of rabies during the test period test and did develop VNA titers. The growing pigs inoculated with the ERAGS strain via the IM route showed higher VNA titers than did those receiving oral administration. FAT and RT-PCR assays were unable to detect RABV in several tissues, including brain samples from the sows. CONCLUSION: Our results suggest that the ERAGS strain was safe in growing pigs and sows and induced moderate VNA titers in pigs.

Comparison of Morphine and Remifentanil on the Duration of Weaning from Mechanical Ventilation / 대한구급학회지

BACKGROUND: A randomized, multicenter, open-label, parallel group study was performed to compare the effects of remifentanil and morphine as analgesic drugs on the duration of weaning time from mechanical ventilation (MV). METHODS: A total of 96 patients with MV in 6 medical and surgical intensive care units were randomly assigned to either, remifentanil (0.1-0.2 mcg/kg/min, n = 49) or morphine (0.8-35 mg/hr, n = 47) from the weaning start. The weaning time was defined as the total ventilation time minus the sum of controlled mode duration. RESULTS: Compared with the morphine group, the remifentanil-based analgesic group showed a tendency of shorter weaning time (mean 143.9 hr, 89.7 hr, respectively: p = 0.069). Secondary outcomes such as total ventilation time, successful weaning rate at the 7th of MV day was similar in both groups. There was also no difference in the mortality rate at the 7th and 28th hospital day. Kaplan-Meyer curve for weaning was not different between the two groups. CONCLUSIONS: Remifentanil usage during the weaning phase tended to decrease weaning time compared with morphine usage.

Comparison of Morphine and Remifentanil on the Duration of Weaning from Mechanical Ventilation / 대한중환자의학회지

BACKGROUND: A randomized, multicenter, open-label, parallel group study was performed to compare the effects of remifentanil and morphine as analgesic drugs on the duration of weaning time from mechanical ventilation (MV). METHODS: A total of 96 patients with MV in 6 medical and surgical intensive care units were randomly assigned to either, remifentanil (0.1-0.2 mcg/kg/min, n = 49) or morphine (0.8-35 mg/hr, n = 47) from the weaning start. The weaning time was defined as the total ventilation time minus the sum of controlled mode duration. RESULTS: Compared with the morphine group, the remifentanil-based analgesic group showed a tendency of shorter weaning time (mean 143.9 hr, 89.7 hr, respectively: p = 0.069). Secondary outcomes such as total ventilation time, successful weaning rate at the 7th of MV day was similar in both groups. There was also no difference in the mortality rate at the 7th and 28th hospital day. Kaplan-Meyer curve for weaning was not different between the two groups. CONCLUSIONS: Remifentanil usage during the weaning phase tended to decrease weaning time compared with morphine usage.

Current Status of Intensive Care Units Registered as Critical Care Subspecialty Training Hospitals in Korea

There is a lack of information on critical care in Korea. The aim of this study was to determine the current status of Korean intensive care units (ICUs), focusing on the organization, characteristics of admitted patients, and nurse and physician staffing. Critical care specialists in charge of all 105 critical care specialty training hospitals nationwide completed a questionnaire survey. Among the ICUs, 56.4% were located in or near the capital city. Only 38 ICUs (17.3%) had intensive care specialists with a 5-day work week. The average daytime nurse-to-patient ratio was 1:2.7. Elderly people > or = 65 yr of age comprised 53% of the adult patients. The most common reasons for admission to adult ICUs were respiratory insufficiency and postoperative management. Nurse and physician staffing was insufficient for the appropriate critical care in many ICUs. Staffing was worse in areas outside the capital city. Much effort, including enhanced reimbursement of critical care costs, must be made to improve the quality of critical care at the national level.

Postoperative nausea and vomiting after total thyroidectomy: sevoflurane combined with prophylactic ramosetron vs. propofol-based total intravenous anesthesia / 대한마취과학회지

BACKGROUND: The frequent and distressing adverse events (AEs) of postoperative nausea and vomiting (PONV) are of major concern in 63-84% of adult patients undergoing thyroidectomy. We conducted this prospective study to compare two prophylactic strategies; sevoflurane combined with ramosetron and propofol-based total intravenous anesthesia in a homogenous group of non-smoking women undergoing total thyroidectomy. METHODS: In the current prospective study, we enrolled a consecutive series of 64 female patients aged between 20 and 65 years with an American Society of Anesthesiologists physical status of I or II who were scheduled to undergo elective total thyroidectomy under general anesthesia. Patients were randomized to either the SR (sevoflurane and remifentanil) group or the TIVA group. We evaluated the incidence and severity of PONV, the use of rescue anti-emetics and the severity of pain during the first 24 h after surgery. RESULTS: There were no significant differences in the proportion of the patients with a complete response and the Rhodes index, including the occurrence score, distress score and experience score, between the two groups. In addition, there were no significant differences in the proportion of the patients who were in need of rescue anti-emetics or analgesics and the VAS scores between the two groups. CONCLUSIONS: In conclusion, TIVA and ramosetron prophylaxis reduced the expected incidence of PONV in women undergoing total thyroidectomy. In addition, there was no significant difference in the efficacy during the first 24 h postoperatively between the two prophylactic regimens.

The efficacy of sevolflurane inhalation alone or its combination with intravenous remifentanil against withdrawal movements on rocuronium injection in children / 대한마취과학회지

BACKGROUND: The aims of this study were to compare the efficacy of sevoflurane inhalation alone, intravenous remifentanil alone, and the combination of sevoflurane inhalation and remifentanil as pretreatment for the prevention of rocuronium-induced withdrawal movement in pediatric patients. METHODS: In this prospective, randomized study, 90 American Society of Anesthesiologists physical status I or II pediatric patients aged 3 to 10 years were randomly allocated to one of three treatment groups: The Group S comprising the patients receiving sevoflurane inhalation, the Group R comprising those doing intravenous remifentanil 0.5 microg/kg and the Group C comprising those doing sevoflurane inhalation+intravenous remifentanil 0.5 microg/kg. The response of the patients was graded based on a 4-point scale. RESULTS: The overall incidence of withdrawal movement on rocuronium injection was 54% (16/30) in the Group S, 57% (17/30) in the Group R and 17% (5/30) in the Group C. There was no significant difference in the incidence of withdrawal movements on rocuronium injection between the Group S and Group R. In addition, the incidence of withdrawal movements and generalized movement on rocuronium injection was significantly lower in the Group C as compared with the Group S and R (P < 0.05). CONCLUSIONS: Our results indicate not only that there was no significant difference in the degree of the effect in lowering the incidence of withdrawal movements on rocuronium injection between sevoflurane inhalation and intravenous remifentanil but also that it was significantly higher when combined with intravenous remifentanil as compared with the single use of sevoflurane inhalation or intravenous remifentanil.

The role of spinal adrenergic receptors on the antinociception of ginsenosides in a rat postoperative pain model / 대한마취과학회지

BACKGROUND: The effect of spinal adrenergic and cholinergic receptors on the anti-nociceptive effect of intrathecal ginsenosides was determined in a rat postoperative pain model. METHODS: Catheters were placed into the intrathecal space of male Sprague-Dawley rats. Postoperative pain was evoked by an incision to the plantar surface of a hind paw. Withdrawal thresholds was used as a nociceptive parameter and was measured with a von Frey filament. After observing the effect of intrathecal ginsenosides, an alpha-1 adrenergic receptor antagonist (prazosin), an alpha-2 adrenergic receptor antagonist (yohimbine), a muscarinic acetylcholine receptor antagonist (atropine), and a nicotinic acetylcholine receptor antagonist (mecamylamine) were given 10 min before administration of the ginsenosides to analyze the contribution of spinal adrenergic and cholinergic receptors on the antinociceptive effect of ginsenosides. RESULTS: Paw incision decreased withdrawal threshold in incised site of paw, but no change of withdrawal threshold was not seen in non-incised site. The intrathecal ginsenosides increased withdrawal threshold of the incised paw in a dose-dependent manner. Pre-treatment with both prazosin and intrathecal yohimbine antagonized the anti-nociceptive effect of the ginsenosides. However, pre-treatments with atropine or mecamylamine had any effect on the antinociceptive activity of ginsenosides. CONCLUSIONS: Intrathecal ginsenosides are effective in attenuation of postoperative pain induced in the rat model. Anti-nociceptive action of ginsenosides is partially mediated by spinal adrenergic receptors, but does not appear to be related to spinal cholinergic receptors.

Antinociceptive Effects of Amiloride and Benzamil in Neuropathic Pain Model Rats

Amiloride and benzamil showed antinocicepitve effects in several pain models through the inhibition of acid sensing ion channels (ASICs). However, their role in neuropathic pain has not been investigated. In this study, we investigated the effect of the intrathecal amiloride and benzamil in neuropathic pain model, and also examined the role of ASICs on modulation of neuropathic pain. Neuropathic pain was induced by L4-5 spinal nerve ligation in male Sprague-Dawley rats weighing 100-120 g, and intrathecal catheterization was performed for drug administration. The effects of amiloride and benzamil were measured by the paw-withdrawal threshold to a mechanical stimulus using the up and down method. The expression of ASICs in the spinal cord dorsal horn was also analyzed by RT-PCR. Intrathecal amiloride and benzamil significantly increased the paw withdrawal threshold in spinal nerve-ligated rats (87%+/-12% and 76%+/-14%, P=0.007 and 0.012 vs vehicle, respectively). Spinal nerve ligation increased the expression of ASIC3 in the spinal cord dorsal horn (P=0.01), and this increase was inhibited by both amiloride and benzamil (P<0.001 in both). In conclusion, intrathecal amiloride and benzamil display antinociceptive effects in the rat spinal nerve ligation model suggesting they may present an alternative pharmacological tool in the management of neuropathic pain at the spinal level.

Dexmedetomidine for sedation of patients undergoing elective surgery under regional anesthesia / 대한마취과학회지

BACKGROUND: Dexmedetomidine may be useful as a sedative agent. However, it has been reported that dexmedetomidine decreases systemic blood pressure, heart rate, and cardiac output in a dose-dependent manner. The purpose of this study was to determine the appropriate dose of intravenously administered dexmedetomidine for sedation. METHODS: Forty-five American Society of Anesthesiologists physical status I-II patients under spinal anesthesia received dexmedetomidine 1 microg/kg intravenously as a loading dose. The patients were randomly allocated to one of three groups for maintenance dose: Group A (0.25 microg/kg/hr), Group B (0.50 microg/kg/hr), and Group C (0.75 microg/kg/hr). The hemodynamic variables and the Ramsay Sedation Scale (RSS) score were recorded for all patients. The numbers of patients who developed hypotension, bradycardia, or inadequate sedation necessitating further drug treatment were also recorded. RESULTS: Systolic blood pressure, heart rate, and SpO2 were decreased, and RSS score was increased significantly at both 20 min and 40 min after injection of dexmedetomidine in the three study groups compared to baseline, without significant differences between the groups. The prevalence of hypotension, but not that of bradycardia or adjunctive midazolam administration, exhibited a positive correlation with the dose of dexmedetomidine. CONCLUSIONS: Intravenous injection of dexmedetomidine 1 microg/kg followed by continuous administration at infusion rates of 0.25, 0.50, or 0.75 microg/kg/hr produced adequate levels of sedation. However, there was a tendency for the incidence of hypotension to increase as the dose increased. To minimize the risk of hemodynamic instability, a dose of 0.25 microg/kg/hr may be the most appropriate for continuous administration of dexmedetomidine.

Additive interaction of intrathecal ginsenosides and neostigmine in the rat formalin test / 대한마취과학회지

BACKGROUND: The authors evaluated the effect of intrathecal mixture of ginsenosides with neostigmine on formalin-induced nociception and made further clear the role of the spinal muscarinic (M) receptors on the activity of ginsenosides. METHODS: A catheter was located in the intrathecal space of male Sprague-Dawley rats. Pain was evoked by injection of formalin solution (5%, 50 microl) to the hindpaw. Isobolographic analysis was done to characterize drug interaction between ginsenosides and neostigmine. The antagonism of ginsenosides-mediated antinociception was determined with M1 receptor antagonist (pirenzepine), M2 receptor antagonist (methoctramine), M3 receptor antagonist (4-DAMP), M4 receptor antagonist (tropicamide). The expression of muscarinic receptor subtypes was examined with RT-PCR. RESULTS: Intrathecal ginsenosides and neostigmine produced an antinociceptive effect during phase 1 and phase 2 in the formalin test. Isobolographic analysis revealed an additive interaction between ginsenosides and neostigmine in both phases. Intrathecal pirenzepine, methoctramine, 4-DAMP, and tropicamide reversed the antinociception of ginsenosides in both phases. M1-M4 receptors mRNA detected in spinal cord of naive rats and the injection of formalin decreased the expression of M1 receptor mRNA, but it had no effect on the expression of other three muscarinic receptors mRNA. Intrathecal ginsenosides little affected the expression of all of muscarinic receptors mRNA in formalin-injected rats. CONCLUSIONS: Intrathecal ginsenosides additively interacted with neostigmine in the formalin test. Furthermore, M1-M4 receptors exist in the spinal cord, all of which contribute to the antinocieption of intrathecal ginsenosides.

Anesthetic requirements and stress hormone responses in chronic spinal cord-injured patients undergoing surgery below the level of injury: nitrous oxide vs remifentanil / 대한마취과학회지

BACKGROUND: Nitrous oxide (N2O) and remifentanil both have anesthetic-reducing and antinociceptive effects. We aimed to determine the anesthetic requirements and stress hormone responses in spinal cord-injured (SCI) patients undergoing surgery under sevoflurane anesthesia with or without pharmacodynamically equivalent doses of N2O or remifentanil. METHODS: Forty-five chronic, complete SCI patients undergoing surgery below the level of injury were randomly allocated to receive sevoflurane alone (control, n = 15), or in combination with 67% N2O (n = 15) or target-controlled infusion of 1.37 ng/ml remifentanil (n = 15). Sevoflurane concentrations were titrated to maintain a Bispectral Index (BIS) value between 40 and 50. Measurements included end-tidal sevoflurane concentrations, mean arterial blood pressure (MAP), heart rate (HR), and plasma catecholamine and cortisol concentrations. RESULTS: During surgery, MAP, HR, and BIS did not differ among the groups. Sevoflurane concentrations were lower in the N2O group (0.94 +/- 0.30%) and the remifentanil group (1.06 +/- 0.29%) than in the control group (1.55 +/- 0.34%) (P < 0.001, both). Plasma concentrations of norepinephrine remained unchanged compared to baseline values in each group, with no significant differences among groups throughout the study. Cortisol levels decreased during surgery as compared to baseline values, and returned to levels higher than baseline at 1 h after surgery (P < 0.05) without inter-group differences. CONCLUSIONS: Remifentanil (1.37 ng/ml) and N2O (67%) reduced the sevoflurane requirements similarly by 31-39%, with no significant differences in hemodynamic and neuroendocrine responses. Either remifentanil or N2O can be used as an anesthetic adjuvant during sevoflurane anesthesia in SCI patients undergoing surgery below the level of injury.

Effects on Intubating Conditions of Pretreatment with Remifentanil before Administration of Cisatracurium / 전남의대학술지

Cisatracurium provides superior hemodynamic stability with only minor release of histamine, and its metabolism via Hoffman elimination is independent of organ function. However, use of cisatracurium is limited because of reportedly slower onset and unsatisfactory intubating conditions. Many studies have shown that remifentanil might provide reliable intubating conditions; thus, we hypothesized that pretreatment with remifentanil before administration of cisatracurium might result in acceptable intubating conditions. Sixty healthy patients scheduled for elective surgery were enrolled and randomly divided into three groups: saline (Group I, n=20), remifentanil 0.5 microg/kg (Group II, n=20), and remifentanil 1.0 microg/kg (Group III, n=20). The anesthesia was induced with propofol 2.0 microg/kg given intravenously over 30 s followed by injection over 30 s of a different dose of remifentanil according to the study protocol. We examined the intubating condition by jaw relaxation, vocal cord state, and diaphragmatic response 90 s after administering cisatracurium. We also measured mean blood pressure, heart rate, and the onset time, which is the interval from the end of neuromuscular blocking agent administration until suppression of maximal T1 on a train-of four sequence. The mean values of the intubating condition after endotracheal intubation in Groups II and III were significantly lower than that in Group I (p<0.005), although the overall onset time of cisatracurium did not differ significantly between the three groups. Our results suggest that supplementation with remifentanil in an induction regimen with cisatracurium improves the quality of the intubating condition even though the onset time of cisatracurium is not shortened.

Urinary trypsin inhibitor attenuates lipopolysaccharide-induced neutrophil activation / 대한마취과학회지

BACKGROUND: Urinary trypsin inhibitor (UTI), which is speculated to have anti-inflammatory effects, is one of serine protease inhibitors found in human urine and blood. The present study was conducted to clarify the effect of urinary trypsin inhibitor (UTI) on human neutrophil activation and its intracellular signaling mechanism in vitro. METHODS: To assess the possible interactions between UTI and lipopolysaccharide (LPS) in neutrophil activation, neutrophils from human blood were incubated with varying concentrations of UTI (1, 10, 100, 1,000 and 10,000 U/ml) plus LPS (100 ng/ml) or LPS alone in 24-well plates (5 x 106 cells/well). We measured protein levels for interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-alpha) using enzyme-linked immunosorbent assay (ELISA) kits after 4 hours of incubation period. To elucidate the intracellular signaling pathway, we also measured the levels of phosphorylation of p38, ERK1/2 and JNK via Western blot analysis. Moreover, the nuclear levels of nuclear factor-kappa B (NF-kappaB) were determined with electrophoretic mobility shift assays (EMSA). RESULTS: UTI decreased the expression of inflammatory cytokines, including TNF-alpha and IL-6, and activation of intracellular signaling pathways, such as JNK, but not P38, ERK1/2 and nuclear translocation of NF-kappaB. CONCLUSIONS: UTI can attenuate LPS-induced neutrophil responses and may partially contribute to the treatment of neutrophil-mediated inflammatory diseases.

Spinal Cord Stimulation for Refractory Angina Pectoris: A Case Report

Refractory angina pectoris is defined as angina refractory to optimal medical treatment and standard coronary revascularization procedures. Despite recent therapeutic advances, patients with refractory angina pectoris are not adequately treated. Spinal cord stimulation is a minimally invasive and reversible technique which utilizes electrical neuromodulation by means of an electrode implanted in the epidural space. It has been reported to be an effective and safe treatment for refractory angina pectoris. We report a case of spinal cord stimulation which has effectively relieved chest pain due to coronary artery disease in a 40-year-old man. This is the first report of spinal cord stimulation for treatment of refractory angina pectoris in South Korea.

Effect of manassantin B, a lignan isolated from Saururus chinensis, on lipopolysaccharide-induced interleukin-1beta in RAW 264.7 cells / 대한마취과학회지

BACKGROUND: Elevated systemic levels of pro-inflammatory cytokines cause hypotension during septic shock and induce capillary leakage in acute lung injury. Manassantin B has anti-inflammatory and anti-plasmoidal properties. This study examined the effects of manassantin B on lipopolysaccharide (LPS)-induced inflammatory response in murine macrophages. METHODS: RAW 264.7 macrophage cells were incubated without or with (1, 3 and 10 microM) manassantin B and without or with (100 ng/ml) LPS. Manassantin B dissolved in phosphate buffered saline was added to the medium 1 h prior to the addition of LPS. The degree of activation of mitogen-activated protein kinase (MAPK) including extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun amino terminal kinases (JNK) and p38 MAPK, and the level of interleukin (IL)-1beta were determined 30 min and 24 h after the addition of LPS respectively. RESULTS: Manassantin B inhibited the production of IL-1beta and attenuated the phosphorylations of ERK1/2 and p38 MAPK, but not that of JNK, in RAW 264.7 cells treated with LPS. CONCLUSIONS: Manassantin B reduces LPS-induced IL-1beta expression through effects on ERK1/2- and p38 MAPK-mediated pathways. Manassantin B has potential as a potent anti-inflammatory drug for use in pathological processes such as sepsis or acute lung injury.

Lipid-Emulsion Propofol Less Attenuates the Regulation of Body Temperature than Micro-Emulsion Propofol or Sevoflurane in the Elderly

PURPOSE: Anesthesia and surgery commonly cause hypothermia, and this caused by a combination of anesthetic-induced impairment of thermoregulatory control, a cold operation room environment and other factors that promote heat loss. All the general anesthetics markedly impair normal autonomic thermoregulatory control. The aim of this study is to evaluate the effect of two different types of propofol versus inhalation anesthetic on the body temperature. MATERIALS AND METHODS: In this randomized controlled study, 36 patients scheduled for elective laparoscopic gastrectomy were allocated into three groups; group S (sevoflurane, n=12), group L (lipid-emulsion propofol, n=12) and group M (micro-emulsion propofol, n=12). Anesthesia was maintained with typical doses of the study drugs and all the groups received continuous remifentanil infusion. The body temperature was continuously monitored after the induction of general anesthesia until the end of surgery. RESULTS: The body temperature was decreased in all the groups. The temperature gradient of each group (group S, group L and group M) at 180 minutes from induction of anesthesia was 2.5+/-0.6degrees C, 1.6+/-0.5degrees C and 2.3+/-0.6degrees C, respectively. The body temperature of group L was significantly higher than that of group S and group M at 30 minutes and 75 minute after induction of anesthesia, respectively. There were no temperature differences between group S and group M. CONCLUSION: The body temperature is maintained at a higher level in elderly patients anesthetized with lipid-emulsion propofol.

Effects of inspired oxygen fraction in discriminating venous from arterial blood in percutaneous central venous catheterization under general anesthesia / 대한마취과학회지

BACKGROUND: A low fraction of inspired oxygen (FiO2) increases venous deoxygenated hemoglobin concentrations, making the color of the blood darker. The present study was aimed to determine the effects of FiO2 on the ability to discriminate venous from arterial blood. METHODS: One-hundred and sixty surgical patients undergoing percutaneous central venous access of the internal jugular vein were randomly assigned to receive an FiO2 of 0.2, 0.4, 0.6, or 1.0 (n = 40 each) for at least 20 min prior to central line placement under general anesthesia. Vascular access was achieved with a 22-gauge needle; 2 ml of blood was withdrawn and shown to three physicians including the operator. Each of them was asked to identify the blood as 'arterial', 'venous' or 'not sure'. Simultaneous blood gas analysis of the samples was performed on blood taken from the puncture site and the artery after visual comparison to confirm blood's origin and hemodynamic measurements. RESULTS: Lowering FiO2 progressively increased venous deoxygenated hemoglobin concentrations (2.24 +/- 1.12, 3.30 +/- 1.08, 3.66 +/- 1.15, and 3.71 +/- 1.33 g/dl) in groups having an FiO2 of 1.0, 0.6, 0.4 and 0.2, respectively (P < 0.001), thereby facilitating the 'venous' blood identification (P < 0.001). Neither heart rate nor mean arterial pressure differed among the groups. None developed hypoxemia (percutaneous hemoglobin oxygen saturation < 90%) in any group during the study period. CONCLUSIONS: A low FiO2 increases venous deoxygenated hemoglobin levels, thereby facilitating the recognition by clinicians of its venous origin in percutaneous central venous catheterization under general anesthesia.