Trajectories of oxygen saturation within 6–72 hours after birth in neonates at moderate altitude:a prospective longitudinal cohort study

Trajectories of pulse oxygen saturation(SpO_(2))within the first few days after birth are important to inform the strategy for identifying asymptomatic hypoxemic disease but remain poorly substantiated at higher altitudes.Methods We performed a longitudinal cohort study with consecutive neonates at a local hospital in Luchun County,China,at an altitude of 1650 m between January and July 2020.We repeatedly measured the pre-and post-ductal SpO_(2)values at 6,12,18,24,36,48,and 72 hours after birth for neonates without oxygen supplements.All neonates underwent echocardiography and were followed up to 42 days after discharge.We included neonates without hypoxemic diseases to characterize the trajectories of SpO_(2)over time using a linear mixed model.We considered the 2.5th percentile as the reference value to define hypoxemic conditions.Results A total of 1061 neonates were enrolled.Twenty-five had non-cardiac hypoxemic diseases,with 84%(21/25)presenting with abnormal SpO_(2)within 24 hours.One had tetralogy of Fallot identified by echocardiography.Among the 1035 asymptomatic neonates,SpO_(2)values declined from 6 hours after birth,reached a nadir at 48 hours,and tended to level off thereafter,with identical patterns for both pre-and post-ductal SpO_(2).The reference percentile was 92%for both pre-and post-ductal SpO_(2)and was time independent.Conclusions A decline within 48 hours features SpO_(2)trajectories within the first 72 hours at moderate altitude.Our findings suggest that earlier screening may favorably achieve a benefit–risk balance in identifying asymptomatic hypoxemic diseases in this population.

Reliability of pressure cuff induced transient limb ischemia in conscious rabbits

Background The protective effects of transient limb ischemia （TLI） induced by several cycles of intermittent pressure cuff inflation and deflation for a period have been widely investigated,however the reliability of this protocol has not been clearly verified.Our study aimed to investigate the reliability of pressure cuff induced TLI in conscious rabbits.Methods Eight New Zealand rabbits were subjected to TLI without anesthesia.TLI consisted of 3 cycles of ischemia and reperfusion induced by inflating the cuff placed on the left lower limb to 200 mmHg for 5 minutes followed by deflating the cuff for 5 minutes.Skin color,pulse oxygen saturation （SpO2）,pulse rate （PR）,plethysmogram waveform （Pleth）,and ultrasound detection of the blood flow in the extremity distal to the ischemic segment were observed to confirm ischemia and reperfusion during TLI.The frequency of severe limb movement during TLI was also recorded to assess the amenability of this protocol in conscious rabbits.Results The skin color of the extremity distal to the ischemic segment changed from bright red to dark purple after inflating the cuff to 200 mmHg,and returned to normal after cuff deflation.Pleth,PR and SpO2 disappeared during ischemia and restored during reperfusion in the monitor.Blood flow of the left posterior tibial artery was completely blocked by a pressure of 200 mmHg during ischemia,and recovered immediately after cuff deflation.The frequency of severe limb movement in supine position was higher than that in prone position （P〈0.05）,but there was no severe limb movement that could result in disturbance to ischemia when the rabbits were placed in prone position.Conclusion Pressure cuff inflating to 200 mmHg for 5 minutes and deflating for 5 minutes is a reliable regimen to induce TLI in conscious rabbits.

An innovative method to evaluate the severe level of general Qi deficiency

OBJECTIVE:The study aim was to use existing relevant indexes to establish an index series for the quantitative measurement of Qi deficiency pattern(QDP) in Traditional Chinese Medicine(TCM).METHODS:Seventeen indexes of arterial oxygen saturation(SaO_2),TCM pulse diagnosis,heart rate,and blood pressure were integrated into an index series,and 94 selected subjects were divided into a healthy control group,a mild QDP group,and a typical QDP group.All three groups were then synchronously given a breath-holding(BH) test and index detections using TCM apparatus for auxiliary diagnosis and treatment and a photoplethysmograph.The detections were carried out repeatedly until there was no monotonic change in the value of the minimal SaO_(2d)uring a BH measurement(SaO_(2 min)) or in the duration of BH during a BH measurement(TBH).RESULTS:BH measurement and index detection data from 380 eligible cases were analyzed and a significant intergroup difference was found for 12 indexes.CONCLUSION:An index series for quantitative QDP measurement could comprise the 12 effective indexes:RSaO_(2d)(rate of decline of SaO_(2d)uring a BH measurement),RSaO_(2r)(recovery rate of SaO_2 after a BH measurement),SaO_(2 min),BFV(blood flow velocity),TSaO_(2d)(the time at which SaO_2 started declining during a BH measurement),TBH,TSa_(O2 min)(the time of occurrence of the minimal SaO_(2d)uring a BH measurement),TSa O_(2 max)(the time of occurrence of the maximal SaO_2 after a BH measurement),PTP(pulse-touching pressure),SBP(systolic blood pressure),PWV(pulse wave velocity),and DBP(diastolic blood pressure).Of the indexes,RSaO_(2d)could play akey role in quantitative QDP measurement;RSaO_(2r) and Sa O_2 mincould be used to differentiate the QDP symptom of shortness of breath and as early-warning indexes for chronic obstructive pulmonary disease.BFV,TSaO_(2d),and TBHcould be used to quantitatively assess the QDP symptoms of spontaneous perspiration and shortness of breath.