Mild Hypoxemia Research Articles

Nocturnal Arterial Oxygen Saturation and Academic Performance in a Community Sample of Children

Hypoxemia, often assessed via pulse oximetry, is associated with neurocognitive deficits in children. The best way to qualify hypoxemia, or which level of hypoxemia already affects cognition, is unknown. We assessed the association of pulse oximetry-derived variables that qualify hypoxemia with impaired academic performance in mathematics in a population-based cross-section of 995 primary school children who underwent overnight home recordings of motion-resistant new-generation pulse oximeter saturation (SpO2). Impaired academic performance in mathematics was based on the last school report and defined as grade 4 to 6 on a 6-point scale (ie, approximately the lowest quintile grades). Of 10 variables under study, only the nadir of the SpO2 values was significantly associated with impaired performance. Categories of this variable representing mild (ie, 91%-93% SpO2; odds ratio: 1.65; 95% confidence interval: 1.06-2.56) and moderate hypoxemia (ie, < or =90% SpO2 ; odds ratio: 2.28; 95% confidence interval: 1.30-4.01) both were associated with impaired performance in mathematics. We suggest using the nadir of the SpO2 values in an overnight study to qualify hypoxemia in future studies. This variable may predict neurocognitive deficits in school children. Mild hypoxemia, as yet widely considered benign, may already affect cognition in childhood. SpO2

Potential factors of interorgan signals in the development of pancreatitis-associated acute lung injury and acute respiratory distress syndrome

The incidence of the pulmonary complications in patients with acute pancreatitis is up to 60%, from mild hypoxaemia without clinical or radiological abnormalities to severe acute lung injury. Although a number of reviews has described clinical evidence of pancreatitis-associated lung injury (PALI), there is still a lack of information on potential interorgan signalling involved in the development of PALI. The present review discusses the potential factors that have been considered as candidates responsible for interorgan signalling coupling pancreatitis to lung injury. Inflammatory mediators produced from the pancreas, leucocyte system and extrapancreatic organs may directly or indirectly contribute to the high concentration in the circulation, activate circulating leucocytes, initiate the inflammatory responses of pulmonary resident cells or induce acute lung injury. Circulating leucocytes have been suggested to play an important role in interorgan signalling during the development of PALI, by producing ...

Effects of skin on bias and reproducibility of near-infrared spectroscopy measurement of cerebral oxygenation changes in porcine brain

The influence of skin on the bias and reproducibility of regional cerebral oxygenation measurements is investigated using cw near-infrared spectroscopy (NIRS). Receiving optodes are placed over the left and right hemispheres of a piglet (C3, C4 EEG placement code) and one transmitting optode centrally (Cz position). Optical densities (OD) are measured during stable normo, mild, and deep hypoxemia. This is done for skin condition 1: all optodes on the skin; skin condition 2: transmitting optode on the skin and one receiving optode on the skull; and skin condition 3: all optodes on the skull. Absolute changes of oxy- (cO2Hb), deoxyhemoglobin (cHHb), and total hemoglobin (ctHb) concentrations [micromolL] are calculated from the ODs. These absolute changes are calculated for each skin condition with respect to normoxic condition. Additionally, for skin condition 2, the difference of concentration changes between receiver 1 (skull) and receiver 2 (skin) is calculated. The effect of skin removal is an average increase of attenuation changes by a factor of 1.66 (=0.51 OD) and of the concentration changes due to the arterial oxygen saturation steps by 23%. We conclude that skin significantly influences regional oxygenation measurements. Nevertheless, it is hypothesized that the estimated concentration changes are dominated by changes of the oxygenation in the brain.

Pathophysiological aspects of severe acute pancreatitis-associated lung injury

Acute pancreatitis is an inflammatory process which occurs in severe form in 20% of all patients, out of whom 15%-25% will die. The incidence of severe acute pancreatitis-associated lung injury (APALI) varies from 15% to 55% and its severity varies from mild hypoxemia to acute respiratory distress syndrome (ARDS). Acute lung injury (ALI) and ARDS are the most significant manifestations of extra abdominal dysfunctions in severe acute pancreatitis with mortality rate as high as 60% in the first week of the onset of illness. Different pathophysiological mechanisms of severe acute pancreatitis-associated lung injury have been described. The role of enzymes, adhesion molecules, neutrophils, fibronectin and various inflammatory mediators has been emphasized. Mechanism of the acute lung injury associated with the acute pancreatitis is very complex and has not been clear yet. There is no specific therapeutic procedure and mortality rate is very high. Therefore, further studies are necessary to address this acute and growing problem in intensive medicine.

Human Skin Fibroblasts as a Feeder Layer, Alternative to Mouse 3T3 Fibroblasts, for Cultivation of Human Corneal Epithelial Cells

Chlorine is a pulmonary toxicant to which humans can be exposed through accidents or intentional releases. Acute effects of chlorine inhalation in humans and animal models have been well characterized, but less is known about persistent effects of acute, high-level chlorine exposures. In particular, animal models that reproduce the long-term effects suggested to occur in humans are lacking. Here, we report the development of a rabbit model in which both acute and persistent effects of chlorine inhalation can be assessed. Male New Zealand White rabbits were exposed to chlorine while the lungs were mechanically ventilated. After chlorine exposure, the rabbits were extubated and were allowed to survive for up to 24 h after exposure to 800 ppm chlorine for 4 min to study acute effects or up to 7 days after exposure to 400 ppm for 8 min to study longer term effects. Acute effects observed 6 or 24 h after inhalation of 800 ppm chlorine for 4 min included hypoxemia, pulmonary edema, airway epithelial injury, inflammation, altered baseline lung mechanics, and airway hyperreactivity to inhaled methacholine. Seven days after recovery from inhalation of 400 ppm chlorine for 8 min, rabbits exhibited mild hypoxemia, increased area of pressure–volume loops, and airway hyperreactivity. Lung histology 7 days after chlorine exposure revealed abnormalities in the small airways, including inflammation and sporadic bronchiolitis obliterans lesions. Immunostaining showed a paucity of club and ciliated cells in the epithelium at these sites. These results suggest that small airway disease may be an important component of persistent respiratory abnormalities that occur following acute chlorine exposure. This non-rodent chlorine exposure model should prove useful for studying persistent effects of acute chlorine exposure and for assessing efficacy of countermeasures for chlorine-induced lung injury.

Utility of Bronchoalveolar Lavage in Immunocompromised Children: Diagnostic Yield and Complications

Immunocompromised children are at high risk for developing pneumonia due to opportunistic pathogens. The role of bronchoalveolar lavage (BAL) in the evaluation of such patients is still controversial. We reviewed the hospital records of immunosuppressed patients with respiratory symptoms who had undergone BAL in the pediatric department of the Hospital Clinico de la Pontificia Universidad Católica of Chile. Sixty-eight BAL were performed on 54 children (mean age: 7.5 years) receiving wide-spectrum antibiotic treatment. The most frequent respiratory signs and symptoms were fever (90%) and cough and respiratory distress (81%); 18% had neutropenia and 43% thrombocytopenia. A specific pathogen was identified in BAL samples for 25 patients (37%). The pathogens isolated were bacteria in 21 cases, viruses in 6, Pneumocystis carinii in 5, fungi in 4, and Mycobacterium tuberculosis in one. Fourteen (19%) of the children who underwent BAL were on mechanical ventilation. Outcome was satisfactory in all cases. Twenty-one complications were recorded, 17 of which were minor (mild hypoxemia or fever) and 4 major, requiring tracheal intubation. No deaths were recorded. Evaluation by fiberoptic bronchoscopy together with BAL proved to be a safe procedure with an adequate diagnostic yield that made it possible to determine the etiology of the pulmonary infiltrates seen in chest x-rays. Both positive and negative results of BAL were useful for treating the patients.

Relationship between exercise desaturation and pulmonary haemodynamics in COPD patients.

Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) has traditionally been explained as an effect of hypoxaemia. Recently, other mechanisms, such as arterial remodelling caused by inflammation, have been suggested. The aim of this study was to investigate whether exercise-induced PH (EIPH) could occur without concurrent hypoxaemia, and whether exercise-induced hypoxaemia (EIH) was regularly accompanied by increased pulmonary artery pressure or pulmonary vascular resistance index (PVRI). Pulmonary haemodynamics in 17 patients with COPD of varying severity, but with no or mild hypoxaemia at rest, were examined during exercise equivalent to the activities of daily living (ADL) and exhaustion. EIPH occurred in 65% of the patients during ADL exercise. Pulmonary arterial pressure during exercise was negatively correlated with arterial oxygen tension, but EIPH was not invariably accompanied by hypoxaemia. Conversely, EIPH was not found in all patients with EIH. The resting PVRI was negatively correlated with arterial oxygen tension during ADL exercise, but an elevated PVRI without EIH occurred in 35% of the patients. In conclusion, exercise-induced pulmonary hypertension occurred during exercise equivalent to the activities of daily living in chronic obstructive pulmonary disease patients with no or mild hypoxaemia at rest. Although pulmonary artery pressure and arterial oxygen tension were negatively correlated during exercise, a consistent relationship between hypoxaemia and pulmonary hypertension could not be demonstrated. This may indicate that mechanisms other than hypoxaemia contribute significantly in the development of pulmonary hypertension in these patients.

Endoscopist administered propofol for upper-GI EUS is safe and effective: a prospective study in 500 patients

Background The administration of propofol for endoscopic sedation by a qualified person, other than the endoscopist, is safe and effective. The aim of this study was to determine if propofol can be administered safely and effectively by the endoscopist performing the procedure. Methods All patients referred for upper-GI EUS were eligible for inclusion in the study. Exclusion criteria included the following: age less than 18 years, American Society of Anesthesiology physical status class greater than 2, a potential for difficulty in airway maintenance, and allergy to propofol constituents. The endoscopist administered propofol as an intravenous bolus followed by a constant infusion. Adverse events, drug dosage, complications, and patient/endoscopist satisfaction were recorded. Results A total of 500 patients (285 women, 215 men; mean age 53.4 [14.8 years]) were enrolled. Mean propofol dose was 301 mg (range 100-1000 mg). Mean procedure time was 19 minutes (range 3-70 minutes). The required examination was completed in all cases. There was no major adverse event. Oxygen desaturation (oxygen saturation < 95%) occurred in 16 (3%) patients. There were 4 (1%) cases of mild hypoxemia (saturation < 90%) but no case of severe hypoxemia (saturation <85%). The endoscopist rated the 92% of the procedures as “very smooth” or “smooth” and regarded administration of propofol as “easy” for 92%. All patients said they would prefer the same method of sedation if the procedure were repeated. Conclusions Endoscopist-administered propofol is safe and effective in selected patients.

Long-Term Oxygen Therapy Stops the Natural Decline of Endurance in COPD Patients with Reversible Hypercapnia

Background: Respiratory muscle weakness is one of the most important causes of hypercapnia in patients with COPD. There is evidence that stable hypercapnic patients will benefit from long-term oxygen therapy (LTOT). Objectives: The prognostic role of reversible hypercapnia in COPD is still unclear. Early implementation of LTOT in these patients may influence endurance time and mortality. Methods: In this pilot study, we investigated 28 patients (26 males, 49–74 years) with COPD, advanced airflow limitation [forced expiratory volume in 1 s (percentage of predicted value) 40.8 ± 10.2] and mild hypoxaemia (pO₂ 66.5 ± 6.3 mm Hg). All patients had developed a moderate reversible hypercapnia during an acute exacerbation or during exercise testing (peak pCO₂ 48.0 ± 2.5 mm Hg). Patients were allocated randomly to a control group (n = 14) or an LTOT group (n = 14). The two groups were well matched in terms of physiological data. Lung function, endurance time (cycle ergometer), dyspnoea score, blood gases and LTOT compliance were measured at baseline and every 6 months over a period of 3 years. Results: Endurance time increased from 6.4 ± 2.7 min at baseline to 7.1 ± 2.7 min after 1 year in the LTOT group and decreased from 6.1 ± 3.0 to 4.9 ± 3.8 min in the controls (p < 0.05). After 1 year, the end-exercise dyspnoea score was significantly lower in the LTOT group (4.5 ± 1.5) than in the controls (5.7 ± 1.9). Conclusion: COPD patients with reversible hypercapnia and mild hypoxaemia benefit from LTOT in terms of endurance time and a reduction of exertional dyspnoea after 1 year.

Effect of acute hyperoxia during exercise on quadriceps electrical activity in active COPD patients.

This study investigated whether acute hyperoxia improves electrical muscle activity in active chronic obstructive pulmonary disease (COPD) patients with mild hypoxemia (rest PaO(2) = 9.1 +/- 0.4 kPa). Two identical incremental exercise tests were performed by nine patients while breathing either air or 30% oxygen. Pulmonary gas exchanges, venous concentrations of lactate and pyruvate, and the electromyographic signal of the quadriceps muscle (vastus lateralis and vastus medialis) were sampled each minute. Peak working capacity increased significantly in hyperoxia (94.4 +/- 5.2W) compared with normoxia (85.4 +/- 5.8W, P < 0.01). During hyperoxic exercise and for a given work load, oxygen uptake was increased (P < 0.001) and ventilation decreased (P < 0.05). Lactate concentration was significantly decreased (P < 0.01) at isowork level and during recovery (respectively - 26% and at least - 15%). In the quadriceps muscle, M-wave amplitude (P < 0.05), root mean square (P < 0.01) and root mean square/oxygen uptake ratio (P < 0.001) were significantly increased during hyperoxic exercise compared with room air. Although median frequency values did not differ between conditions, the median frequency was significantly decreased for higher exercise intensity in hyperoxic condition. These modifications reflected better aerobic metabolism, later emergence of muscle fatigue, and greater muscle excitability and activation for the same level of exercise under hyperoxic condition. These data suggest that the acute addition of oxygen in active COPD patients improves their muscle electrical activity during dynamic exercise. Hypoxemia-induced skeletal muscle dysfunction most probably acts through mechanisms based on oxygen availability.

Sleep and chronic obstructive pulmonary disease.

Patients with COPD who are hypoxaemic during wakefulness become more hypoxaemic during sleep. The most severe episodes of nocturnal desaturation generally occur during REM sleep. There is a strong relationship between nocturnal O2 saturation and the level of daytime PaO2: the more pronounced daytime hypoxaemia, the more severe nocturnal hypoxaemia. The worsening of hypoxaemia is due to a variable combination of alveolar hypoventilation and ventilation-perfusion mismatching, alveolar hypoventilation being the predominant mechanism, at least during REM sleep. The consequences of sleep-related hypoxaemia include peaks of pulmonary hypertension due to hypoxic pulmonary vasoconstriction, generally observed in patients with marked daytime hypoxaemia. Cardiac arrhythmias have been described but their clinical relevance has not been established. The prevalence of obstructive sleep apnoea syndrome (OSAS) is not greater in chronic obstructive pulmonary disease (COPD) patients than in the general population, but this association (Overlap Syndrome) is not rare since COPD and OSAS are both frequent diseases. Overlap patients are at a higher risk of developing respiratory insufficiency than are pure OSAS patients. Polysomnography is only indicated in COPD patients who are suspected of having OSAS. The treatment of nocturnal hypoxaemia is conventional O2 therapy (> or = 16/24 h) in COPD patients with marked daytime hypoxaemia (PaO2 < 55-60 mmHg) and conventional O2 therapy plus nocturnal non-invasive ventilation in some patients with marked hypercapnia. At present data are not sufficient for justifying the use of isolated nocturnal oxygen therapy in COPD patients with nocturnal desaturation but with mild daytime hypoxaemia (PaO2 > 60 mmHg).

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Sleep and chronic obstructive pulmonary disease

Sleep disorders are pervasive in patients with chronic obstructive pulmonary disease (COPD). The patient with COPD is especially vulnerable to sleep-induced gas exchange aberrations. Most sleep disturbances affect the quality of life and some potentially affect survival in these patients. These issues impact treatment of these patients. Insomnia is very common in COPD but might respond to inhaled anticholinergic agents. The use of hypnotics in the hypercapnic patient with severe COPD might be dangerous. The incidence of sleep apnea in COPD patients is allegedly very high, but recent studies suggest this association to be artifactual. Nocturnal oxygen desaturation, which is common in these patients, occurs even in mild COPD. This clinical complication might reflect sleep-disordered breathing or REM sleep-related hypoventilation. We need cost-effective and reliable methods to help distinguish between these causes without routinely resorting to formal polysomnography. Development of sound clinical algorithms to address this clinical dilemma is indeed a focus for future research. Some of these patients might require continuous positive pressure therapy, whereas others might need long-term oxygen therapy. Although oxygen therapy in COPD patients with only mild hypoxemia and nocturnal desaturation has not uniformly been shown to be beneficial, it is perhaps too soon to abandon this important clinical intervention in these patients.

Influence of exercise training on cardiac baroreflex sensitivity in patients with COPD.

Decreased spontaneous cardiac baroreflex sensitivity (BRS), which could lead to the onset of cardiovascular events, has been demonstrated in chronic obstructive pulmonary disease patients. This study evaluates the effects of an exercise training programme on BRS. Twenty-one chronic obstructive pulmonary disease patients (mean+/-SD age 62+/-9 yrs; forced expiratory volume in one second 43.6+/-18.1% of the predicted value) with mild hypoxaemia (arterial oxygen tension 8.96+/-1.18 kPa) were compared to 18 healthy age-matched subjects. BRS was calculated as the slope of the baroreflex sequences between spontaneous changes in systolic blood pressure and subsequent consecutive relative risk deviation length, and was measured in the supine position and following head-up tilt for sympathetic stimulation. Pulmonary function test results and blood gas levels, measured only in patients, did not change after the training programme. Exercise training increased the maximal sustained workload (16.5%) and peak oxygen consumption (20.5%). Before training, BRS was lower in patients than in controls (2.7+/-1.5 versus 7.8+/-4.9 ms x mmHg(-1)) and tilting induced a smaller reduction in BRS (13 versus 34%). After training, BRS increased to 3.4+/-2.6 ms x mmHg(-1) in patients but remained lower than in controls. The response to the tilt test remained unchanged after training. It is concluded that, in chronic obstructive pulmonary disease patients, exercise training is associated with a gain in spontaneous baroreflex sensitivity, reflecting cardiovascular benefits.

Safety and Efficacy of Ketamine Sedation for Infant Flexible Fiberoptic Bronchoscopy

To describe our experience with ketamine sedation during infant flexible fiberoptic bronchoscopy. Retrospective chart review. Infants were sedated with midazolam and ketamine with or without fentanyl. The sedation regimen, final procedure performed, procedure duration, and complications were recorded. Complication rates between infants <or= 6 months or > 6 months of age and between infants with upper vs lower airway symptoms were compared by chi(2) test with a contingency table. Fifty-nine procedures were performed in 55 patients aged 6.1 +/- 3.1 months (mean +/- SD). Sedation was achieved with ketamine and midazolam (n = 30) or ketamine, midazolam, and fentanyl (n = 29). Bronchoscopy with BAL was performed in 44 patients and bronchoscopy alone in 3 patients. In 11 patients, severe upper airway obstruction and/or anomalies prevented subglottic passage of the bronchoscope. One patient could not be adequately sedated. There were no major complications. Minor complications occurred in 14 patients (23.7%), most commonly mild hypoxemia (n = 9). Brief central apnea developed in three patients. Complication rates were unaffected by age or indication for bronchoscopy. Infant flexible fiberoptic bronchoscopy can be safely and effectively performed using ketamine sedation. Complications, especially mild hypoxemia, appear more common in infants, likely due to smaller airway diameter. Regardless of the sedative(s) used, additional vigilance is required when performing bronchoscopy in this population.

Extensive preoperative testing is not necessary in morbidly obese patients undergoing gastric bypass.

Morbidly obese patients are considered at high risk for perioperative complications and often undergo extensive testing for preoperative clearance. We analyzed prospectively collected data from 193 patients undergoing weight loss surgery between November 2000 and November 2002. Preoperative chest x-ray examination, pulmonary function tests, noninvasive cardiac testing, and blood work were performed routinely. Preoperative testing identified abnormalities on eight chest x-ray films (4%) and 29 electrocardiograms (15%), none of which required preoperative intervention. Spirometry was abnormal in 41 patients (21%); logistic regression identified preexisting asthma as predictive of obstructive physiology (odds ratio [OR] 3.3; 95% confidence interval [CI] 1.2 to 8.9), and body mass index as predictive of restrictive physiology (OR 1.1; 95% CI 1.01 to 1.2). Arterial blood gases identified only one case of severe hypoxemia requiring intervention. Mild hypoxemia was associated with increasing age (OR 14.5; 95% CI 1.8 to 114). Echocardiography demonstrated four abnormalities (2%); previous history of cardiac disease was the only risk factor (OR 14.5; 95% CI 1.8 to 114). Complete blood count did not identify 84% and 50% of the patients with iron (n=31) and vitamin B(12) (n=12) deficiencies, respectively. Age, body mass index, and history of asthma were associated with abnormal pulmonary function tests and previous cardiac disease with abnormal cardiac testing. These tests are not mandatory as a routine preoperative evaluation and can be used selectively on the basis of medical history.

Characteristics of 1 062 patients with SARS in early stage in Beijing

AIM: To sumarize the clinical features of patients with SARS in early stage. METHODS: The clinical data of patients with SARS who were admitted to hospitals in the periods of 1 to 7 days after onset of illness. The early stage of SARS was identified by the syndromes and signs of lungs, oxygenation index and the examination of imaging. RESULTS: The positive rates of the reference parameters were similar in the 1st day and 2nd to 3rd day, but changed obviously in the later days. The period of 1 to 3 days was therefore considered as the early stage of SARS. The study showed that 88.7 percent of patients got fever, 98.8 percent of patients had reported fever and 16.3 % patients with chilly, 4.3 percent of patients even shiver. 20 percent of patients had the unspecific syndrome, such as fatigue, headache, myalgia, and arthralgia. 16.1% patients had congestion in throat and 8.4% patients with pharyngalgia. Rhinorrhea, sneezing, skin rash and tumefaction of tonsil or lymph nodes were rare (the rates were 3.4%, 2.5%, 0.9% and 0.3% respectively). 4.3 percent of patients occurred dianrrhea, but no hematenesis and hematochezia. Nausea, vomiting and other positive signs of abdumen were not common. About one third patients presented cough, 14.6% expectoration, 7% chest distress and suffocated. The sign of lung was usually lacked, and the rate of moist rales were only 4.9%. 71.4% patients‘ artery pressure of oxygen decreased, 20.9% and 27. 8% patients oxygenation index and oxygen satureation also went down slightly. The reducing rate of WBC, lymphocyte and PLT were 22.5%, 36.4% and 13.4% respectively, but there were 6.4% patients with high WBC count. The mean counts of CD3, CD4, and CD8 cells decreased obviously and their positive rates were more than 90%. Most patients of SARS (about 80% to 90%) had inflammatory shadow in chest films, majority had one lungfield shadow and minority with multi-lungfields, but some patients had normal films of chest X-ray (19.9%) and CT (9.1%). 10-15% patients‘ liver and renal functions were abnormal. 13-16% patients with high values of creatinine kinase, but that of CK-MB was only 5.9%. CONCLUSION: In early stage of SARS (1 to 3 days), almost all the patients get fever, some have the unspecific symptom, but the sign of catarrh and tumefaction of lymph nodes are rare. About one third patients have cough and 14.6% expectoration, and present mild hypoxemia, but usually lack the sign of lung. In 22.5% and 36.4% patients WBC and lymphocyte reduce, and also the mean counts of CD3, CD4 and CD8 cells reduce significantly, the positive rates are more than 90%. About 80% (X-ray) to 90% (CT) patients show abnormal chest films in radiologic examination, but someones have the normal results of chest X-ray (19.9%) and CT (9.1%). About 10-16% patients suffer the damage of the liver, kidney and heart.

A Case of Bilateral Diffuse Infiltration

Pulmonary alveolar proteinosis is a rare disorder in which lipoproteinaceous material accumulates within the alveoli. We report a case of pulmonary alveolar proteinosis in a 41 year old female patient. She complained of a dry cough in the preceding 6 months. She presented symptoms of mild hypoxemia ...

Strenuous exercise increases plasmatic and urinary leukotriene E4 in cyclists.

The purpose of this study was to investigate plasma and urinary levels of leukotriene (LT) and the changes in pulmonary function induced by strenuous exercise in highly trained cyclists (HT) with mild exercised-induced hypoxemia (EIH). Nine HT and five untrained subjects (UT) performed a 30-min exercise at 78% of their VO2peak. Leukotriene E4 (LTE4) was assayed in plasma and urine. Pulmonary function tests and pulmonary diffusion capacity (DLCO) were examined before and after exercising. Ear arterialized blood gases were assessed at rest and during exercise. The mean drop in partial oxygen pressure was 15 mmHg in HT during exercise; and the DLCO decreased by 7.5% following exercise. No significant changes were found in forced vital capacity or forced expiratory flows. LTE4 levels increased significantly in HT following exercise: urinary LTE4 was 42.9 +/- 6.3 ng.mmol-1 creatinine at rest and 66.3 +/- 11.9 ng.mmol-1 creatinine 2 hrs after exercise, and plasma LTE4 rose from 528 +/- 91 pg.mL-1 at rest to 897 +/- 123 pg.mL-1 after exercise. By contrast, urinary LTE4 level was unchanged in the UT group. Among the HT group, there was no significant correlation between urinary LTE4 changes and PO2, air flow rates, or DLCO changes. These results suggest that strenuous exercise induces an increase of LTE4 release in highly trained cyclists with mild EIH. These changes in LTE4 levels were not related to significant impairment of lung function.

Extensive preoperative testing is not necessary in morbidly obese patients undergoing gastric bypass

Morbidly obese patients are considered at high risk for perioperative complications and often undergo extensive testing for preoperative clearance. We analyzed prospectively collected data from 193 patients undergoing weight loss surgery between November 2000 and November 2002. Preoperative chest x-ray examination, pulmonary function tests, noninvasive cardiac testing, and blood work were performed routinely. Preoperative testing identified abnormalities on eight chest x-ray films (4%) and 29 electrocardiograms (15%), none of which required preoperative intervention. Spirometry was abnormal in 41 patients (21%); logistic regression identified preexisting asthma as predictive of obstructive physiology (odds ratio [OR] 3.3; 95% confidence interval [CI] 1.2 to 8.9), and body mass index as predictive of restrictive physiology (OR 1.1; 95% CI 1.01 to 1.2). Arterial blood gases identified only one case of severe hypoxemia requiring intervention. Mild hypoxemia was associated with increasing age (OR 14.5; 95% CI 1.8 to 114). Echocardiography demonstrated four abnormalities (2%); previous history of cardiac disease was the only risk factor (OR 14.5; 95% CI 1.8 to 114). Complete blood count did not identify 84% and 50% of the patients with iron (n = 31) and vitamin B12 (n = 12) deficiencies, respectively. Age, body mass index, and history of asthma were associated with abnormal pulmonary function tests and previous cardiac disease with abnormal cardiac testing. These tests are not mandatory as a routine preoperative evaluation and can be used selectively on the basis of medical history.