Arterial oxygen saturation profiles in healthy preterm infants

AIM: To construct a reference range of SpO2 values in healthy preterm infants using a simple data logging device. METHODS: Thirty three healthy preterm infants were monitored for a continuous period of 4 hours at rest using an Ohmeda Biox 3700 E Pulse Oximeter and an electronic data logger (Rustrack Ranger). Stored data were downloaded and saved as individual files on a personal computer. RESULTS: The study group median and 5th and 95th percentiles were used to construct a cumulative frequency curve of time against SpO2 value, representing the normal reference range of SpO2 profiles in healthy preterm infants. CONCLUSION: Comparison of an infant's SpO2 profile against this curve may be more helpful in guiding supplemental oxygen treatment in that individual than a figure for a mean SPO2 and its standard deviation.     

Arterial oxygen saturation in Tibetan and Han infants born in Lhasa, Tibet

BACKGROUND: Reduced oxygen availability at high altitude is associated with increased neonatal and infant mortality. We hypothesized that native Tibetan infants, whose ancestors have inhabited the Himalayan Plateau for approximately 25,000 years, are better able to maintain adequate oxygenation at high altitude than Han infants, whose ancestors moved to Tibet from lowland areas of China after the Chinese military entered Tibet in 1951. METHODS: We compared arterial oxygen saturation, signs of hypoxemia, and other indexes of neonatal wellbeing at birth and during the first four months of life in 15 Tibetan infants and 15 Han infants at 3658 m above sea level in Lhasa, Tibet. The Han mothers had migrated from lowland China about two years previously. A pulse oximeter was placed on each infant's foot to provide measurements of arterial oxygen saturation distal to the ductus arteriosus. RESULTS: The two groups had similar gestational ages (about 38.9 weeks) and Apgar scores. The Han infants had lower birth weights (2773 +/- 92 g) than the Tibetan infants (3067 +/- 107 g), higher concentrations of cord-blood hemoglobin (18.6 +/- 0.8 g per deciliter, vs. 16.7 +/- 0.4 in the Tibetans), and higher hematocrit values (58.5 +/- 2.4 percent, vs. 51.4 +/- 1.2 percent in the Tibetans). In both groups, arterial oxygen saturation was highest in the first two days after birth and was lower when the infants were asleep than when they were awake. Oxygen saturation values were lower in the Han than in the Tibetan infants at all times and under all conditions during all activities. The values declined in the Han infants from 92 +/- 3 percent while they were awake and 90 +/- 5 percent during quiet sleep at birth to 85 +/- 4 percent while awake and 76 +/- 5 percent during quiet sleep at four months of age. In the Tibetan infants, oxygen saturation values averaged 94 +/- 2 percent while they were awake and 94 +/- 3 percent during quiet sleep at birth and 88 +/- 2 percent while awake and 86 +/- 5 percent during quiet sleep at four months. Han infants had clinical signs of hypoxemia--such as cyanosis during sleep and while feeding--more frequently than Tibetans. CONCLUSIONS: In Lhasa, Tibet, we found that Tibetan newborns had higher arterial oxygen saturation at birth and during the first four months of life than Han newborns. Genetic adaptations may permit adequate oxygenation and confer resistance to the syndrome of pulmonary hypertension and right-heart failure (subacute infantile mountain sickness).     

Postural hypoxemia in quadriplegic patients

Quadriplegic patients frequently undergo unusual positional changes, including head-down tilt. To determine if hypoxemia develops in this position and whether it is related to the duration of quadriplegia, five patients were studied within 1 year of injury (group A) and five after 1 year from injury (group B). Arterial blood gases were obtained in the seated and 45-degree head-down position. Group A patients had a decrease in arterial partial pressure of oxygen in the head-down position (p less than 0.025), while group B patients did not (p greater than 0.4). This study demonstrated that quadriplegic patients have positional hypoxemia early in their course. This probably results from relative hypoventilation of the upper lung fields caused by flaccid paralysis of the intercostal muscles. The positional hypoxemia disappears with time, presumably because of the change from flaccid to spastic paralysis of the intercostal muscles.     

Changes in oxygen saturation and transcutaneous carbon dioxide and oxygen levels in patients undergoing fibreoptic bronchoscopy

Though women have a lower absolute risk of disease than men at all ages, almost all the risk factors for cardiovascular disease carry the same or higher relative risk for women as for men. Moreover, the attributable risk is higher in older women than in men. Epidemiologic studies show that recent decreases in coronary heart disease mortality are in some cases greater among women than men. Interventional studies show that women appear to have as good or better a response than men to cholesterol-lowering in secondary prevention. Antihypertensive drug therapy is effective in preventing clinical endpoints in elderly women. These observations imply that an overall estimation of cardiovascular risk in women needs careful consideration. Because established therapies appear to be effective in high risk women, postmenopausal and probably also elderly women are important target groups for preventive efforts. The value of prevention for premenopausal women should not be underestimated, but should on the whole be approached through population-based strategies.     

Effect of sputum induction on arterial oxygen saturation and spirometry in HIV-infected patients

We wanted to study the effect of sputum induction on forced expiratory volume in one second (FEV1) and on oxygen saturation in normal controls, asymptomatic human immunodeficiency virus (HIV)-seropositive individuals, and HIV-seropositive patients under investigation for suspected Pneumocystis carinii pneumonia (PCP). Over a five month period, sputum induction with ultrasonically nebulized 3% saline was performed on 110 HIV-seropositive patients with suspected PCP, 10 asymptomatic HIV-seropositive patients, and 15 normal controls. Oxygen saturation (peak, trough and change in oxygen saturation (delta O2)) was measured throughout the procedure using pulse oximetry, and these results compared with the chest radiograph and the final pulmonary diagnosis. In addition, the effect of sputum induction on FEV1 was measured in the 15 control subjects and 10 asymptomatic HIV-seropositive patients. Compared with bronchoalveolar lavage, sputum induction had a diagnostic sensitivity for PCP of 76%. Chest radiography was 79% sensitive, and had specificity of 83%. Patients with PCP had lower peak and trough oxygen saturation values compared with the non-PCP group (mean peak 95 vs 97%; mean trough 88 vs 91%), and greater falls in O2 saturation during the procedure (mean delta O2 7.6 vs 5.5%). One subject desaturated to 76%, requiring supplemental oxygen. Sputum induction caused significant but temporary falls in FEV1 both in control and HIV-seropositive groups (mean maximum fall in FEV1 10.4 vs 12.5%). We conclude that although sputum induction causes significant falls in oxygen saturation and FEV1, it remains sensitive and safe, and provides a useful alternative to bronchoscopy for the diagnosis of PCP.     

Effect of temazepam on oxygen saturation and sleep quality at high altitude: randomised placebo controlled crossover trial

OBJECTIVE: To determine the effects of temazepam on the quality of sleep and on oxygen saturation during sleep in subjects at high altitude. DESIGN: Randomised, blinded, crossover, placebo controlled trial. SETTING: Base camp at Mount Everest (altitude 5300 m). SUBJECTS: 11 members of British Mount Everest Medical Expedition recently arrived at base camp. INTERVENTION: Participants were randomly allocated to receive either temazepam 10 mg or placebo on their first night at base camp and the other treatment on the second night. MAIN OUTCOME MEASURES: Quality of sleep (assessed subjectively), mean arterial oxygen saturation value, and changes in saturation values (as measure of periodic breathing) while participants taking temazepam or placebo. RESULTS: All participants noted subjective improvements in sleep. Mean saturation value remained unchanged when temazepam was compared with placebo (74.65% v 75.70%, P = 0.5437). There were fewer changes in oxygen saturation when participants took temazepam and when measured as decreases > 4% below the mean value of saturation each hour (P = 0.0036, paired Student's t test (two tailed)). CONCLUSIONS: Participants taking temazepam at 5300 m showed no significant drop in mean oxygen saturation values during sleep. Both the number and severity of changes in saturation during sleep decreased and the quality of sleep improved. This may be a result of a reduction in the number of awakenings and might lead to greater respiratory stability and fewer episodes of periodic breathing. This has the effect of improving the quality of sleep and reducing the number of periods of desaturation during sleep.     

Estimation of the time course of slow-wave sleep over the night in depressed patients: effects of clomipramine and clinical response

The distribution of slow-wave activity during sleep has been analyzed using a method related to the two-process model of sleep regulation. This method is applied to the analyses of data collected from 21 inpatients with unipolar depression who received the antidepressant clomipramine (CMI) in a pulse-loading protocol. CMI infusion was found to redistribute slow-wave activity, producing more concentration in the early part of the night, and also significantly reduced the fluctuation in slow-wave power as a function of time. These measures also distinguished clinical responders from the nonresponders. Drug responders had a significant redistribution of slow-wave activity to the earlier part of the night as compared to nonresponders. This suggests that measures of the distribution of slow-wave activity over the night may represent a good measure of clinical response to antidepressant therapy and have implications for the interpretation of the two-process model and sleep in depression.     

Children's sleep and cognitive performance: A cross-domain analysis of change over time.

Relations between changes in children's cognitive performance and changes in sleep problems were examined over a 3-year period, and family socioeconomic status, child race/ethnicity, and gender were assessed as moderators of these associations. Participants were 250 second- and third-grade (8–9 years old at Time 1) boys and girls. At each assessment, children's cognitive performance (Verbal Comprehension, Decision Speed) was measured using the Woodcock-Johnson III Tests of Cognitive Abilities, and sleep problems (Sleepiness, Sleep/Wake Problems) were collected via self-report. Individual growth models revealed that children who reported increases in Sleepiness exhibited little growth in Verbal Comprehension over time compared with their peers who reported decreases in Sleepiness, resulting in a nearly 11-point cognitive deficit by the end of the study. These associations were not found for Sleep/Wake Problems or Decision Speed. Child race/ethnicity and gender moderated these associations, with Sleepiness serving as a vulnerability factor for poor cognitive outcomes, especially among African American children and girls. Differences in cognitive performance for children with high and low Sleepiness trajectories ranged from 16 to 19 points for African American children and from 11 to 19 points for girls. Results build substantially on existing literature examining associations between sleep and cognitive functioning in children and are the first to demonstrate that children's sleep trajectories over 3 waves were associated with changes in their cognitive performance over time. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Fetal oxygen saturation and uterine contractions during labor

In the majority of cases, carcinoma of the thyroid presents as a cold nodule by radioiodine and Tc-99m sodium pertechnetate scintigraphy. Whereas the presence of a hot nodule usually implies a benign entity, it does not provide complete assurance against thyroid malignancy. Presented is a rare case of metastatic pure papillary thyroid carcinoma appearing as a hot nodule on Tc-99m sodium pertechnetate and I-123 sodium iodide scintigraphy. The implications of such a case, its management, and review of the pertinent literature are discussed.     

Evaluation of a regional oxygen saturation catheter for monitoring SjvO2 in head injured patients

Exercise in the water offers several physiological advantages to the pregnant woman. The hydrostatic force of water pushes extravascular fluid into the vascular spaces, producing an increase in central blood volume that may lead to increased uterine blood flow. This force is proportional to the depth of immersion. The increase in blood volume is proportional to the woman's edema. A marked diuresis and natriuresis accompanies the fluid shifts. The buoyancy of water supports the pregnant women. Water is thermoregulating. Studies of pregnant women exercising in the water have shown less fetal heart rate changes in the water than on land in response to exertion. Pregnant women's heart rates and blood pressures during water exercise are lower than on land exercise, reflecting the immersion-induced increase in circulating blood volume. The physiology of water exercise offers some compensation for the physiological changes of exercise on land that may beneficially affect pregnancy.     

Evaluation of a continuous cardiac output and mixed venous oxygen saturation catheter in critically ill surgical patients

OBJECTIVE: To evaluate the agreement of continuous cardiac output and mixed venous oxygen saturation measurements, obtained with a modified pulmonary artery catheter, with those values obtained by standard intermittent bolus thermodilution and cooximetry. DESIGN: Prospective, clinical investigation. SETTING: A surgical intensive care unit in a tertiary referral center. PATIENTS: Twenty-one adult critically ill surgical patients, requiring pulmonary artery catheter monitoring. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A modified pulmonary artery catheter capable of continuous monitoring of cardiac output and mixed venous oxygen saturation was used with either an 8.5-Fr or a 9-Fr introducer. At random intervals, the continuous cardiac output measurement was compared with the cardiac output obtained using standard intermittent bolus thermodilution. The system was calibrated every 24 hrs for mixed venous oxygen saturation monitoring. Each saturation obtained by the laboratory cooximeter was compared with that value recorded using the catheter. Data points for 202 pairs of cardiac output (21 patients, 31 catheters) and 65 pairs of mixed venous oxygen saturation (20 patients, 28 catheters) were obtained. The bias and precision of the cardiac output data were 0.49 and 1.01 L/min, respectively. The agreement between the continuous and bolus values decreased as the cardiac output increased. Heart rate did not affect the agreement between the continuous and bolus techniques. The bias and precision of the mixed venous oxygen saturation data were -0.57% and 3.76%, respectively. The hematocrit did not affect the bias or precision of the venous saturation data over the hematocrit range observed (23.2% to 44.6%). Fewer catheter malfunctions were observed when the catheter was used with a 9-Fr introducer than with an 8.5-Fr introducer. CONCLUSIONS: The test catheter adequately measures continuous cardiac output and mixed venous oxygen saturation in the clinical setting. Because intermittent bolus thermodilution is not a true "gold standard" for cardiac output determination, new techniques compared with bolus thermodilution may fail to achieve accuracy expectations. A 9-Fr introducer is recommended, as fiberoptic damage may have occurred when the 8.5-Fr introducer was used.     

Continuous cardiac output and mixed venous oxygen saturation monitoring

Continuous assessment of cardiac output and SVO2 in the critically ill may be helpful in both the monitoring variations in the patient's cardiovascular state and in determining the efficacy of therapy. Commercially available continuous cardiac output (CCO) monitoring systems are based on the pulsed warm thermodilution technique. In vitro validation studies have demonstrated that this method provides higher accuracy and greater resistance to thermal noise than standard bolus thermodilution techniques. Numerous clinical studies comparing bolus with continuous thermodilution techniques have shown this technique similarly accurate to track each other and to have negligible bias between them. The comparison between continuous thermal and other cardiac output methods also demonstrates good precision of the continuous thermal technique. Accuracy of continuous oximetry monitoring using reflectance oximetry via fiberoptics has been assessed both in vitro and in vivo. Most of the studies testing agreement between continuous SVO2 measurements and pulmonary arterial blood samples measured by standard oximetry have shown good correlation. Continuous SVO2 monitoring is often used in the management of critically ill patients. The most recently designed pulmonary artery catheters are now able to simultaneously measure either SVO2 and CCO or SVO2 and right ventricular ejection fraction. This ability to view simultaneous trends of SVO2 and right ventricular performance parameters will probably allow the clinician to graphically see the impact of volume loading or inotropic therapy over time, as well as the influence of multiple factors, including right ventricular dysfunction, on SVO2. However, the cost-effectiveness of new pulmonary artery catheters application remains still questionable because no established utility or therapeutic guidelines are available.     

Hemodynamics, cerebral circulation, and oxygen saturation in Cheyne-Stokes respiration

Because cardiovascular disorders and stroke may induce Cheyne-Stokes respiration, our purpose was to study the interaction among cerebral activity, cerebral circulation, blood pressure, and blood gases during Cheyne-Stokes respiration. Ten patients with heart failure or a previous stroke were investigated during Cheyne-Stokes respiration with recordings of daytime polysomnography, cerebral blood flow velocity, intra-arterial blood pressure, and intra-arterial oxygen saturation with and without oxygen administration. There were simultaneous changes in wakefulness, cerebral blood flow velocity, and respiration with accompanying changes in blood pressure and heart rate approximately 10 s later. Cerebral blood flow velocity, blood pressure, and heart rate had a minimum occurrence in apnea and a maximum occurrence during hyperpnea. The apnea-induced oxygen desaturations were diminished during oxygen administration, but the hemodynamic alterations persisted. Oxygen desaturations were more severe and occurred earlier according to intra-arterial measurements than with finger oximetry. It is not possible to explain Cheyne-Stokes respiration by alterations in blood gases and circulatory time alone. Cheyne-Stokes respiration may be characterized as a state of phase-linked cyclic changes in cerebral, respiratory, and cardiovascular functions probably generated by variations in central nervous activity.     

Psychological states in terminal cancer patients as measured over time.

Examined the level of and the change over time in denial, death anxiety, anxiety, depression, hostility, love, being, and self-esteem in terminal cancer patients. Ss were 30 cancer patients (aged 51–74 yrs), 27 arthritic patients (aged 52–75 yrs) who constituted a chronically ill, but not terminal, control group, and 30 healthy control Ss (aged 51–76 yrs). Psychometric instruments to assess the psychological states (the Multiple Affect Adjective Check List, the Rosenberg Self-Esteem Scale, the Death Anxiety Scale, and the Being and Love scales of the Personal Orientation Inventory) were administered 3 times at 6-wk intervals. The cancer patients had significantly lower death anxiety than the control Ss, and a relative increase in the Being variable over time. There was little evidence of appreciable denial of serious illness in the cancer patients and an inverse relation between death anxiety and denial, which lends some support to clinical opinions that denial protects against death anxiety. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrapartum fetal oxygen saturation monitoring in congenital fetal heart block

Precutaneous Kirschner wire fixation of displaced Gartlands types II and III supracondylar fractures with image guidance remains a preferred procedure for most orthopaedic units. Various K-wire configurations have been in use, but recent objective evaluation of pin stability has favoured two techniques; the 2 crossed pins placed from the medial and lateral epicondyles, and 2 parallel lateral pins when the former technique is impracticable because of swelling. We reviewed patients who had K-wire fixation precutaneously over a 2-year period (Feb 1996 to Feb 1998). There were 44 children, 30 males, 14 females, ages between 1-15 years. 19 patients had (medial and lateral pins) 15, (2 parallel lateral) and 10 patients (2 lateral crossed) precutaneous pin placement respectively. Their postoperative course indicated that maximum stability was obtained with two opposite crossed pins, followed by the 2 paralleled pin method. These observation determined the choice of technique by the surgeons who operated on these patients.     

Variations in prothrombin time and international normalized ratio over 24 hours in warfarin-treated patients

STUDY OBJECTIVE: To determine the variation of prothrombin times and international normalized ratio (INR) over 24 hours in humans. DESIGN: Prospective, parallel study. SETTING: University-affiliated general clinical research center. PATIENTS: Six patients receiving long-term warfarin therapy and six sex-matched controls. INTERVENTIONS: Warfarin was administered to the patients at 6:00 P.M. MEASUREMENTS AND MAIN RESULTS: Prothrombin times and INR were determined every 2 hours over 24 hours. Time of study entry, meals, and sleep cycles were controlled. A significant cosinor rhythm for prothrombin times and INR (p < or = 0.03) occurred in warfarin-treated patients, suggesting that diurnal variation occurs. The mean difference between the peak and trough prothrombin times was 1.8 +/- 0.9 seconds (range 0.8-3 sec) with a mean change of 9.3% +/- 3.7%. The peak prothrombin time and INR values occurred between 4:00 A.M. and 8:00 A.M. in five patients, and trough values between 6:00 P.M. and midnight in five. No significant cosinor rhythm was noted for controls (p > 0.5). CONCLUSION: Significant variations in prothrombin time and INR occurred in patients receiving warfarin therapy, with the highest values occurring in the morning and the lowest in the evening. These results may have clinical implications for patients receiving either high- or low-intensity warfarin therapy.     

Design and evaluation of head unit for wheelchair control by quadriplegic patients

A control unit was designed to allow persons who have lost hand and arm function to control the speed, steering, reversal and on-off switching of an electric wheelchair by means of backward movement and rotation of the head. When possible, shoulder movement was used to control both reversal and on-off switching. Clinical evaluation in 10 patients with quadriplegia and 2 with severe neuromuscular disease showed that the unit neither interfered with nor restrained the patients' residual body movements, permitted use of natural head movements for smooth and fast control of the wheelchair, and was well accepted by and integrated into the life of the patients.     

Arterial blood pressure response to transient arousals from NREM sleep in nonapneic snorers with sleep fragmentation

STUDY OBJECTIVES: To assess the hemodynamic effects of graded arousals during nonrapid eye movement (NREM) sleep in patients with partial upper airway obstruction during sleep without obstructive sleep apnea/hypopnea, overnight beat-to-beat BP was recorded in six patients. SETTING: At the end of each nonapneic obstructive event, EEG responses were graded as follows: grade 2, grade 1, and grade 0 were defined as increased high-frequency EEG lasting >15 s, 3 to 15 s, and no EEG arousals according to the American Sleep Disorders Association, respectively. MEASUREMENTS AND RESULTS: The following were observed during grade 0, 1, and 2 EEG patterns (mean+/-SD): systolic pressure increased by 7.1+/-1.5, 11.7+/-1.9, and 14.2+/-3.4 (p<0.005), respectively; diastolic pressure increased by 4.6+/-0.6, 6.7+/-1.7, and 9.4+/-3.0 (p<0.005), respectively; heart rate increased by 2.9+/-0.4, 3.9+/-2.2, and 8.6+/-4.6 (p<0.005), respectively. CONCLUSIONS: We conclude that nonapneic-nonhypopneic obstructive events are followed by arterial systemic pressure increases whose magnitude varies with the grade of the arousal.