AIM2 contributes to the maintenance of intestinal integrity via Akt and protects against Salmonella mucosal infection.

The mechanism regulating the gastrointestinal epithelial barrier remains poorly understood. We herein demonstrate that Absent in melanoma-2 (AIM2) contributes to the maintenance of intestinal barrier integrity and defense against bacterial infection. AIM2-deficient mice displayed an increased susceptibility to mucosal but not systemic infection by Salmonella typhimurium, indicating a protective role for AIM2 in the gastrointestinal tract. In a Salmonella colitis model, compared with wild-type mice, AIM2(-/-) mice exhibited more severe body weight loss, intestinal damage, intestinal inflammation, and disruption of basal and activated epithelial cell turnover. In vivo and in vitro data showed that AIM2 restricted the early epithelial paracellular invasion of Salmonella and decreased epithelial permeability. The decreased epithelial barrier in AIM2(-/-) mice might be attributed to the altered expression of tight junction proteins that contribute to epithelial integrity. AIM2 promoted the expression of tight junction proteins through Akt activation. Together, these results suggest that AIM2 is required for maintaining the integrity of the epithelial barrier.

Edaravone protects endotoxin-induced liver injury by inhibiting apoptosis and reducing proinflammatory cytokines

Studies have shown that edaravone may prevent liver injury. This study aimed to investigate the effects of edaravone on the liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in female BALB/c mice. Edaravone was injected into mice 30 min before and 4 h after GalN/LPS injection. The survival rate was determined within the first 24 h. Animals were killed 8 h after GalN/LPS injection, and liver injury was biochemically and histologically assessed. Hepatocyte apoptosis was measured by TUNEL staining; proinflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] in the liver were assayed by ELISA; expression of caspase-8 and caspase-3 proteins was detected by Western blot assay; and caspase-3 activity was also determined. Results showed that GalN/LPS induced marked elevations in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Edaravone significantly inhibited elevation of serum AST and ALT, accompanied by an improvement in histological findings. Edaravone lowered the levels of TNF-α and IL-6 and reduced the number of TUNEL-positive cells. In addition, 24 h after edaravone treatment, caspase-3 activity and mortality were reduced. Edaravone may effectively ameliorate GalN/LPS-induced liver injury in mice by reducing proinflammatory cytokines and inhibiting apoptosis.

Edaravone protects endotoxin-induced liver injury by inhibiting apoptosis and reducing proinflammatory cytokines.

Studies have shown that edaravone may prevent liver injury. This study aimed to investigate the effects of edaravone on the liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in female BALB/c mice. Edaravone was injected into mice 30 min before and 4 h after GalN/LPS injection. The survival rate was determined within the first 24 h. Animals were killed 8 h after GalN/LPS injection, and liver injury was biochemically and histologically assessed. Hepatocyte apoptosis was measured by TUNEL staining; proinflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] in the liver were assayed by ELISA; expression of caspase-8 and caspase-3 proteins was detected by Western blot assay; and caspase-3 activity was also determined. Results showed that GalN/LPS induced marked elevations in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Edaravone significantly inhibited elevation of serum AST and ALT, accompanied by an improvement in histological findings. Edaravone lowered the levels of TNF-α and IL-6 and reduced the number of TUNEL-positive cells. In addition, 24 h after edaravone treatment, caspase-3 activity and mortality were reduced. Edaravone may effectively ameliorate GalN/LPS-induced liver injury in mice by reducing proinflammatory cytokines and inhibiting apoptosis.

Transillumination-assisted orotracheal intubation: a comparison of the Bonfils fibrescope and the lightwand (Trachlight).

BACKGROUND: Because the Bonfils fibrescope has a semi-rigid optical stylet and is similar in shape to a lightwand, we aimed to evaluate and compare the efficacy of transillumination-assisted orotracheal intubation with the Bonfils fibrescope and the Trachlight(TM) lightwand in patients with normal airways. METHODS: As a preliminary investigation to form a basis for later studies, therefore, we performed a randomized, single-blind study of 300 patients with normal airways to compare the efficiency of Trachlight and transillumination-assisted Bonfils orotracheal intubation in these patients. In both groups, orotracheal intubation was performed using a transillumination technique. The first attempt and overall success rates of tracheal intubation, the times required, and any untoward effects were recorded. RESULTS: Although the overall success rates were similar for Bonfils and Trachlight intubations (97.3% and 98.7%, respectively), tracheal intubation was successful on the first attempt in 87.3% of patients with the Bonfils fibrescope compared with 95.3% of patients with the Trachlight (P < 0.05). The mean intubation time for the first attempt was 15 ± 5 s with the Bonfils fibrescope and 9 ± 2 s with the Trachlight (P < 0.001). Patients intubated using the Bonfils fibrescope also experienced significantly more sore throat and hoarseness than those intubated using the Trachlight. CONCLUSIONS: For patients with normal airways, the Trachlight is superior for orotracheal intubation with respect to reliability, rapidity, and safety compared with the Bonfils fibrescope used with the transillumination technique.

Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children.

We compared the minimum local analgesia concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children. Fifty-one boys, undergoing hypospadius repair surgery, were stratified into pre-school or school age groups. After induction of anaesthesia, caudal block was performed with ropivacaine 1 ml.kg⁻¹ of the desired concentration. The first child in each group received ropivacaine 0.125%, and subsequent concentrations were determined by the analgesic response of the previous patient using Dixon's up-and-down method. Under general anaesthesia with 0.7 minimum alveolar concentration of sevoflurane, the minimum local analgesia concentration of ropivacaine for intra-operative caudal block was 34% greater in school age than in pre-school age boys (0.143% (95% CI 0.132-0.157%) vs 0.107% (95% CI 0.089-0.122%), respectively; p < 0.001). This study indicates that a higher concentration of ropivacaine is needed for school age than pre-school age children to provide intra-operative caudal analgesia when combined with general anaesthesia.

Stronger in vitro phagocytosis by monocytes-macrophages is indicative of greater pathogen clearance and antibody levels in vivo.

Monocytes-macrophages are crucial players in specific and nonspecific immune responses to protect organisms from invasion of bacteria or viruses. In this study, monocytes in circulation from 2 lines of Silky and Starbro chickens with different disease resistance were separated and cultured in vitro. After identification with acridine orange (AO), Giemsa staining, and CD14 immunostaining, monocytes-macrophages were used for adherence and phagocytosis test. The overall percentages of adherence of Silky monocytes was 1.5 times greater than that of Starbro (P < 0.01), which were 26.85% +/- 8.24% and 18.34% +/- 8.15%, respectively (mean +/- SD). The monocytes-macrophages phagocytic index, phagocytic product, and percentage of phagocytosis in Silkies were greater than in Star-bros, respectively. The difference of phagocytic index was significant (P < 0.05), that is, 3.70 +/- 1.75 and 1.97 +/- 0.31, respectively (mean +/- SD). Then, 20 Silkies were divided into 2 groups according to phagocytic index: high phagocytic index (HPI) group and low phagocytic index (LPI) group, to study the relationship between phagocytic activity in vitro and pathogen clearance. After being challenged against Salmonella Pullorum C79-13, the Silky birds with HPI produced a 3-fold greater level of specific antibodies compared with those with LPI (P < 0.01), 50.21 +/- 6.67 and 16.85 +/- 4.52, respectively (mean +/- SD). In contrast to LPI birds, HPI birds shed less Salmonella Pullorum bacteria (P < 0.05), that is, 168.98 x 10(8) +/- 294.74 x 10(8) compared to 385.40 x 10(8) +/- 399.94 x 10(8) (mean +/- SD), and the shedding peak of Salmonella Pullorum in the test span appeared 4 d earlier. These results indicated that phagocytosis of monocytes-macrophages had strong effects on antibody titer and bacteria shedding postchallenge, which could be used to predict the disease resistance in animals.

Effect of selection for phagocytosis in dwarf chickens on immune and reproductive characters.

In current study, phagocytosis product (PP) of peripheral blood monocytes was detected among 920 dwarf chickens (460 per sex) at 20 wk of age, and based on discrepancies of PP, the flock was grouped (the highest group, the medium group, and the lowest group). Then serum hemagglutination inhibition antibody titers and subpopulations of T-lymphocytes of each group were examined after inoculations of avian influenza virus H5N2 inactivated vaccine (20 wk of age), avian influenza virus H9 inactivated vaccine (24 wk of age), and Newcastle disease virus-egg drop syndrome virus bigeminal inactivated vaccine (28 wk of age), respectively, to study the relationship between PP and immune response. To gain insight into effects of selection for PP on number of eggs, mean egg weight, fertilization rate, hatchability, and rate of healthy chicks, 9 (3 x 3) mating combinations were conducted. The results showed that (1) selection for higher PP in both sexes benefited to humoral immunity but not CD8(+) T-lymphocyte mediated immunity in dwarf chickens; (2) there were effects of selection for higher PP in hens on fertilization rate (P < 0.05), hatchability (P < 0.05), rate of healthy chicks (P < 0.05), and level of IgY antibody (P < 0.0001); however, hens' PP had no effects on number of eggs (P > or = 0.05) or egg weight (P > or = 0.05) and cocks' PP had no effect (P > or = 0.05) on any trait mentioned above. The results indicated that phagocytosis of peripheral blood monocytes might be an indicator of humoral immunity in dwarf chickens; furthermore, selection of hens with higher PP was not only beneficial to fertilization rate, but also benefited to hatchability and rate of healthy chicks in that the hens had stronger humoral immunity, which might contribute to maternal antibody in eggs.

An evaluation of the TruView EVO2 laryngoscope.

The TruView EVO2 laryngoscope was compared with the traditional Macintosh laryngoscope in 200 patients who required tracheal intubation for elective surgery. Mallampati score determined prior to laryngoscopy was significantly related to the view of the glottis during laryngoscopy for both laryngoscopes. The view of the larynx was better with the TruView EVO2 laryngoscope than with the Macintosh laryngoscope in patients with a Cormack and Lehane grade greater than 1 (p < 0.01). The mean time to intubate was significantly shorter with the Macintosh laryngoscope (34 s) than with the TruView laryngoscope (51 s) (p < 0.01).

Blood gas, hemoglobin, and growth of Tibetan chicken embryos incubated at high altitude.

Metabolism and hatchability are impaired when chicken eggs laid at sea level are incubated at high altitude. The Tibetan chicken is an excellent local poultry breed that inhabits altitudes of 2,900 m and has a hatchability of approximately 75% at that altitude. To understand how Tibetan chicken embryos develop successfully at high altitude, we compared blood gas, pH, hemoglobin concentrations and embryo mass for Tibetan chicken embryos (T) and for embryos from a dwarf breed (D) that normally is reared at sea level. The 2 breeds (T and D) and 2 incubation altitudes (2,900 m = high, H; and 100 m = low, L) were compared at 9, 12, 15, and 18 d of incubation. Embryo weights were lower for the high altitude groups (TH, DH) than for the low altitude groups at all stages of incubation. The embryo mass of TH appeared to increase more quickly than that of DH. Compared with DH, TH embryos had lower arterialized oxygen partial pressure on d 18, higher venous carbon dioxide partial pressure from d 12 to 18, and higher hemoglobin concentration and lower venous blood pH values on d 12 and 15. These findings indicate that the ability of the Tibetan chicken embryos to adapt to the high altitude may be due to the increase in hemoglobin concentration, which augments the blood oxygen-carrying capacity. In addition, the higher venous carbon dioxide partial pressure and lower venous blood pH promote unloading of oxygen from hemoglobin.

Altered angiogenic balance in ulcerative colitis: a key to impaired healing?

Angiogenesis is an essential component of ulcer healing since it assures delivery of oxygen and nutrients to the healing site. Previous studies demonstrated increased serum and tissue levels of vascular endothelial growth factor (VEGF, the most potent angiogenic growth factor) in patients with active ulcerative colitis (UC) and animal models of UC. However, there is no explanation why the healing of UC-related mucosal injury is impaired despite increased expression of VEGF. Expression of angiogenesis inhibitors, angiostatin and/or endostatin, in UC has not been determined before. We examined expression of VEGF, angiostatin, and endostatin in two models of experimental UC. The results revealed that in addition to increased VEGF, both endostatin and angiostatin levels were markedly (2-3-folds) increased in colonic mucosa at early stage of experimental UC. This is the first demonstration that colitis triggers increase in angiostatin and endostatin levels. The results may explain why mucosal lesions heal slowly despite increased VEGF levels, and may provide a novel and mechanistic insight into UC.

Establishment of serum protein pattern for screening colorectal cancer using SELDI-TOF-MS.

AIM: The purpose of this study is to develop a proteomic pattern for distinguishing individuals with colorectal cancer from healthy controls and monitoring micrometastasis using SELDI-TOF-MS. METHODS: A training set consisting of 63 patients with colorectal cancer, 20 patients with benign colorectal diseases and 26 healthy volunteers was used to develop a proteomic model that discriminated colorectal cancer effectively. The sensitivity and specificity of this model was validated by an independent test set. To explore serum proteins changed after operation, the protein profiles of 31 postoperative patients were compared with those of preoperative patients. We also analyzed protein profiles of patients with and without metastasis to monitor micrometastasis. RESULTS: Our study yielded a four-peak model (m/z: 3191.5, 3262.9, 3396.3 and 5334.4) that discriminated cancer from non-cancer samples with sensitivity of 90.3% and specificity of 95.7%. This model was validated in the test set with sensitivity of 87.5% and specificity of 93.8% which was significantly better than the combination use of CEA, CA199 and CA242 (sensitivity 62.4%) for early detection of colorectal cancer. Two peaks (m/z: 2753.8 and 4172.4) were found down-regulated in postoperative samples comparing with preoperative samples. We also detected two proteins (m/z: 9184.4 and 9340.9) that can discriminate patients with primary colorectal cancer from metastatic colorectal cancer. CONCLUSIONS: The four-peak model and two peaks (m/z: 2753.8 and 4172.4) detected in this study have the potential for assistance in diagnostics and therapeutic strategies in colorectal cancer and the two proteins (m/z: 9184.4 and 9340.9) were effective biomarkers for monitoring micrometastasis.

The use of midazolam and small-dose ketamine for sedation and analgesia during local anesthesia.

UNLABELLED: Small-dose ketamine in combination with sedative drugs has increasingly been used for sedation and analgesia in local anesthesia. We compared the clinical efficacy of midazolam with two different ketamine infusion regimens during plastic surgery under local anesthesia. Sixty patients undergoing plastic surgery procedures with local anesthesia were randomly assigned to two groups of 30 patients each in a double-blinded fashion. All patients received a bolus of 0.05 mg/kg midazolam, followed by a stepwise infusion: 1.67 microg x kg(-1) x min(-1) for the first 30 min, then reduced to 1.33 microg x kg(-1) x min(-1) for 90 min and subsequently to 1 microg x kg(-1) x min(-1). Two minutes before the infiltration of local anesthetic solution, a bolus of ketamine 0.3 mg/kg IV was administered, followed by a stepwise infusion of ketamine: Group A, 16.67 microg x kg(-1) x min(-1) for 30 min, 13.3 microg x kg(-1) x min(-1) for 90 min, and subsequently 10 microg x kg(-1) x min(-1); Group B, 8.33 microg x kg(-1) x min(-1) for 30 min, 6.67 microg x kg(-1) x min(-1) for 90 min, and then 5 microg x kg(-1) x min(-1). The level of sedation was evaluated by using the modified Observer's Assessment of Alertness/Sedation scale. We observed the effects of the two ketamine infusion regimens on sedation levels, respiratory and cardiovascular variables, and perioperative side effects. In both groups, midazolam and ketamine produced adequate sedation (with Observer's Assessment of Alertness/Sedation scores of 2-4) without significant respiratory and cardiovascular depression during surgery. However, there were fewer disruptive movements and there was less postoperative vomiting in Group B (P < 0.01). In conclusion, ketamine and midazolam provided satisfactory intraoperative sedation, analgesia, and amnesia in both groups. However, side effects associated with ketamine occurred less often in the smaller-dose ketamine group. IMPLICATIONS: Sedation and analgesia are often provided during local anesthesia. This study demonstrates that a small-dose ketamine infusion in combination with midazolam provided satisfactory intraoperative sedation, analgesia, and amnesia in healthy plastic-surgery patients when it was used to supplement local anesthesia.

[Determination of catechol-O-methyltransferase activity in human erythrocytes by high performance liquid chromatography].

A rapid assay method for catechol-O-methyltransferase (COMT) activity in human erythrocyts by high performance liquid chromatography (HPLC) with UV detection was established. Enzyme activity was determined from erythrocyte lysates using S-adenosyl-L-methionine (SAM) as methyl donor and 3, 4-dihydroxybenzoic acid (DBA) as substrate. The 3-O-methylated reaction products were measured by HPLC with UV detection. The linear range of COMT was from 1 U/mL to 60 U/mL with an average RSD < 10%, and the detection limit was 0.5 U/mL(S/N > or = 5).

Review article: transcription factors and growth factors in ulcer healing.

This review is focused on recent investigations demonstrating a pharmacological and pathophysiologic role in gastroduodenal ulceration for growth factors such as basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), as well as for transcription factors. Our experiments revealed accelerated healing, without decreased gastric acid secretion, of chronic cysteamine-induced duodenal ulcers in rats treated daily for 3 weeks with intragastric administration of bFGF, PDGF or VEGF. Our recent studies also indicate a pathophysiological role of endogenous growth factors in the natural history of experimental duodenal ulcer development and healing. More recently, we investigated the genetic regulation of these growth factors in experimental duodenal ulceration. Since gene expression is most effectively controlled by transcription factors, proteins that bind to cis-acting elements of DNA and guide the binding of polymerase II to start the transcription of specific mRNA, we tested the hypothesis that the expression of IEGs and their transcription factor products, such as Egr-1 and Sp1, might precede the increased synthesis of bFGF, PDGF and VEGF in duodenal ulcer healing. Indeed, the duodenal ulcerogen cysteamine, but not its nonulcerogen and toxic analogue ethanolamine, rapidly increased duodenal (but not gastric) mucosal levels of ET-1, which was followed by enhanced expression of Egr-1 and a decrease in Sp1 in the preulcerogenic stage of duodenal ulceration. These changes in levels of ET-1 and expression of transcription factors were also accompanied by increased expression of the CDK inhibitor p21. Thus, not only growth factors such as bFGF, PDGF and VEGF, but also transcription factors such as Egr-1 and Sp1 and the cell cycle regulator p21, may play a role in the natural history of experimental duodenal ulceration.

The association of type II pneumocytes and endothelial permeability with the pulmonary custocyte system in experimental acute pancreatitis.

BACKGROUND: Pancreatitis-associated pulmonary injury is still associated with substantial mortality, especially when seen as a part of the multiple organ dysfunction syndrome. METHODS: The present study aimed at evaluating alterations in type II pneumocytes and the potential relationship with the development of pulmonary injury after acute haemorrhagic pancreatitis induced by an intraductal infusion of 5% sodium taurodeoxycholate in the rat. RESULTS: The results demonstrated that definite alterations in type II pneumocytes were noted 12 and 24 h after induction of pancreatitis, characterized by an increase in the number of vocalized lamellae, the exposed area of type II pneumocytes to alveolar airspace, cellular separation and apoptosis without alterations in cellular membrane integrity. Dysfunction of the pulmonary endothelial barrier was evidenced by an increase in pulmonary albumin flux and the leakage index as well as the migration of lanthanum probes from capillaries to interstitial tissues. The levels of tumour necrosis factor (TNF) in bronchoalveolar lavage fluid significantly increased during the initial phase (3 and 6 h) after pancreatitis. The phagocytic activity of the pulmonary custocyte system increased 3 and 12 h after induction of pancreatitis. CONCLUSION: Thus, pulmonary endothelial barrier dysfunction, an activated custocyte system, and initial release of TNF seems to be involved in the pathogenesis of pancreatitis-associated type II pneumocyte compromise.

Role of macrophage overactivation in the development of acute pancreatic injury in rats.

BACKGROUND: An increase in systemic inflammatory mediators from stimulated leucocytes and macrophages has been noted during acute pancreatitis. The role of cytolytic inflammatory macrophages and potential mechanisms in the development of acute pancreatic injury and endothelial barrier dysfunction are less well defined. METHODS: Rats were challenged by an intraperitoneal injection of cytolytic or non-cytolytic inflammatory macrophage stimulators at various concentrations. The effects of oxygen free radicals, prostaglandin and extracellular calcium influx on macrophage-associated pancreatic endothelial compromise, measured by pancreatic intravascular plasma volume, pancreatic interstitial fluid volume, and the pancreatic extravascular human serum albumin distribution volume, were explored. RESULTS: Zymosan-induced overactivation of cytolytic inflammatory macrophages resulted in the development of acute pancreatic endothelial dysfunction in a dose- and time-dependent pattern. An increase in pancreatic water content and interstitial fluid volume was observed following a higher dose (0.5 mg/g) of concanavalin A without alteration in plasma lipase level, while thioglycollate medium did not compromise pancreatic endothelial barrier function. Oxygen free radicals, but also prostaglandins and extracellular calcium influx, seemed to be involved in macrophage overactivation-induced pancreatic injury. CONCLUSION: Overactivation of cytolytic macrophages plays a role in the pathogenesis of pancreatic injury by initiating the development of endothelial barrier dysfunction. Multiple inflammatory mediators from overactivated macrophages act as intercellular signals between macrophages and the endothelium during acute pancreatic injury.

Study of the safe threshold of apneic period in children during anesthesia induction.

STUDY OBJECTIVES: (1) To investigate changes in arterial oxygen saturation via pulse oximeter (SpO2) during apnea and after reinstitution of manual ventilation at SpO2 of 95% or 90% following rapid sequence induction of anesthesia in children after 2-minute preoxygenation; (2) to determine whether the setting of a safe threshold of apneic period to an SpO2 of 95% is appropriate in children during anesthetic induction; and (3) to evaluate the influences of age, body weight, and height on the time from the start of apnea to SpO2 of 95%. DESIGN: A clinical study of random design and comparison among groups. SETTING: Operating room of a plastic surgery hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS: 152 infants and children, ASA physical status 1, aged 3 months to 12 years, scheduled for elective plastic surgery. INTERVENTIONS: Patients were divided into three age groups: Group 1-infants 3 months to 1 year (n = 39); Group 2 children 1 to 3 years (n = 41); and Group 3-children 3 to 12 years (n = 72). Patients in each age group were randomly allocated again to Subgroups A and B. After a 2-minute preoxygenation, anesthesia was induced with thiopental 5 mg/kg, fentanyl 5 micrograms/kg and suxamethonium 1.5 mg/kg. Patients were manually ventilated when SpO2 decreased to 90% in Subgroups A and 95% in Subgroups B, respectively, during apnea. MEASUREMENTS AND MAIN RESULTS: SpO2 was measured continuously with a Datex pulse oximeter applied to the right index finger. During apnea, the times for SpO2 to decrease to 09% (T99) and 95% (T99) in all children, and 90% (T90) in Subgroups A were recorded. The time for SpO2 to decrease from 95% to 90% (T95-90) in Subgroups A was also measured. After reinstitution of manual ventilation, the time when SpO2 continued to decrease (T1) and the time from the end of apnea to recovery of SpO2 baseline (T2) were determined. In addition, the lowest value of SpO2 after apnea was also recorded. The results showed that younger children were more susceptible than older children to the risk of hypoxemia during apnea. There were significant differences in T99, T95, T90, and T95-90 between the three age groups T1 and T2 were significantly longer in Group 3 than in Groups 1 and 2. There were significant differences in the lowest values of SpO2 following apnea among the three Subgroups A and between Subgroups A and B of each age group. During apnea, heart rate decreased gradually as SpO2 decreased, showing a significant decrease at SpO2 of 95%. Bradycardia was found in three children in Subgroups A. The apnea time to SpO2 of 95% correlated well with age, weight, and height by linear regression analysis. CONCLUSIONS: The safe threshold of an apneic period setting to an SpO2 of 95% was appropriate in children during anesthesia induction. Despite the same duration of preoxygenation, younger children were more susceptible than elder ones to the risk of hypoxemia during apnea. The apnea time to SpO2 of 95% correlated with age, body weight, and height using linear regression analysis.

A comparative study of early postoperative hypoxemia in infants, children, and adults undergoing elective plastic surgery.

To determine the influence of age on postoperative hypoxemia, we studied postoperative hypoxemia in 1152 patients, from infants to adults, ASA physical status I, undergoing elective plastic surgery. Subjects were divided into four groups on the basis of age: Group 1, infants aged 1 yr or less (n = 108); Group 2, children aged 1-3 yr (n = 240); Group 3, children aged 3-14 yr (n = 482); and Group 4, adults aged 14-58 yr (n = 322). Arterial oxygen saturation (Spo2) levels were recorded while patients were breathing room air in the postanesthesia recovery room shortly after arrival (0 min), and 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 min thereafter. Younger patients showed lower Spo2 levels and a higher incidence of hypoxemia during the early postoperative period. The incidences of hypoxemia (Spo2 = 86%-90%) and severe hypoxemia (Spo2 < or = 85%) in the recovery room were 30.6% and 16.7%, respectively, in Group 1, 20.0% and 10.0% in Group 2, 14.1% and 3.3% in Group 3, and 7.8% and 0.6% in Group 4. Hypoxemia occurred most commonly within 1 h after anesthesia, particularly during the first 40 min in infants and during the first 15 min in older children and adults. A significant correlation was found by linear regression analysis between low Spo2 levels on admission to the recovery room and children's age. Thereafter, Spo2 levels and the incidence of hypoxemia during the early postoperative period were related only to infants' recovery scores.