Letter to the Editor

PEDIATRICS ◽  
1969 ◽  
Vol 43 (4) ◽  
pp. 638-639
Author(s):  
John H. Knelson ◽  
Mary Ellen Avery
Keyword(s):  
Partial Pressure ◽  
Oxygen Tension ◽  
Newborn Infants ◽  
Capillary Blood ◽  
Partial Pressure Of Oxygen ◽  
Oxygen Levels ◽  
Arterial Blood ◽  
Letter To The Editor ◽  
Ambient Oxygen

The letter from Drs. Stefan, Leschin, and Gray raises the important question of the validity of measurements of the partial pressure of oxygen (PO2) in capillary blood. We concur that measurements of oxygen tension are essential in monitoring ambient oxygen levels, and we would agree that, in the absence of shock, values on capillary blood reflect the levels in arterial blood. Fortunately, data exist, at least in normal newborn infants breathing air, that permit evaluation of the usefulness of capillary samples.

Continuous Monitoring of Arterial Oxygen Tension Using a Catheter-Tip Polarographic Electrode in Infants

PEDIATRICS ◽  
1976 ◽  
Vol 57 (2) ◽  
pp. 244-250
Author(s):  
M. Conway ◽  
G. M. Durbin ◽  
D. Ingram ◽  
N. McIntosh ◽  
D. Parker ◽  
...  
Keyword(s):  
Oxygen Tension ◽  
Continuous Monitoring ◽  
Newborn Infants ◽  
Arterial Oxygen Tension ◽  
Oxygen Electrode ◽  
Arterial Oxygen ◽  
Respiratory Illnesses ◽  
Arterial Blood ◽  
Reliable Instrument ◽  
Catheter Tip

An oxygen electrode mounted in the tip of an umbilical artery catheter was used in 36 newborn infants with severe respiratory illnesses, 28 of whom survived. Thirty-seven electrodes were used. The median age at insertion was 4 hours (range, 30 minutes to 122 hours). Three electrodes failed to work and they were removed or replaced, and two could not be properly evaluated. Thirty-two electrodes functioned satisfactorily for 10 to 190 hours (mean, 75 hours) after a one-point calibration against blood sampled through the catheter. Twenty-two did not need recalibrating before they were removed after 10 to 190 hours (mean, 88 hours). Four of the remaining ten electrodes were recalibrated once after 33 to 97 hours and then functioned until removed 15 to 55 hours later. The other six electrodes failed after 32 to 105 hours (mean, 49 hours). Complications were few. A total of 356 arterial blood samples, obtained after the initial calibration and before any recalibration was necessary, gave a correlation coefficient of 0.93 (P < .0001) against an independent system for measuring arterial oxygen tension (Pao2) (Radiometer Type E.5046 oxygen electrode). We conclude that the catheter-tip electrode is a safe and reliable instrument for continuously recording Pao2 in newborn infants which much simplifies the management of serious respiratory illnesses.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

OXYGEN THERAPY IN THE NEWBORN INFANT

PEDIATRICS ◽  
1971 ◽  
Vol 47 (6) ◽  
pp. 1086-1087
Author(s):  
Jerold F. Lucey ◽  
Marvin Cornblath ◽  
Stanley N. Graven ◽  
Sheldon B. Korones ◽  
L. Stanley James ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Newborn Infant ◽  
Newborn Infants ◽  
Arterial Oxygen Tension ◽  
Arterial Oxygen ◽  
Retrolental Fibroplasia ◽  
Arterial Blood ◽  
Increased Risk ◽  
Inspired Oxygen

The following recommendations will appear in the revision of the manual, Standards and Recommendations for Hospital Care of Newborn Infants, scheduled for publication early in 1971. Because the Committee felt a sense of urgency to provide these recommendations to pediatricians, family physicians, and other health professionals caring for newborn infants, they are being published prior to appearance of the manual. The statement has had extensive review by a large number of experts not on the Committee, and their comments and suggestions have been followed in the preparation of the final draft. It was also reviewed and approved by the Committee on Drugs of the Academy at their meeting in San Francisco October 24, 1970. When a newborn infant needs extra oxygen, it must be administered with great care because there is a causal relationship between a higher than normal oxygen tension in arterial blood (60 to 100 mm Hg) and retrolental fibroplasia (retinopathy of prematurity). When the normal O2 tension is exceeded, there is an increased risk of retrolental fibroplasia. The upper limit of arterial oxygen tension and its duration which are safe for these infants is not known. It is probable that even concentrations of 40% of inspired oxygen (formerly considered safe) could be dangerous for some infants. An inspired oxygen concentration of 40% may be insufficient for infants with cardiorespiratory disease to raise the oxygen tension of arterial blood to a normal level. In such instances, an inspired oxygen concentration of 60%, 80%, or higher may be necessary.

Cyanosis in the Newborn

1987 ◽  
Vol 9 (2) ◽  
pp. 36-42
Author(s):  
Martin H. Lees ◽  
Douglas H. King
Keyword(s):  
Oxygen Saturation ◽  
Oxygen Tension ◽  
Newborn Infants ◽  
Fetal Hemoglobin ◽  
Absolute Concentration ◽  
Arterial Blood ◽  
Adult Hemoglobin ◽  
The Absolute

RECOGNITION OF CYANOSIS IN THE NEWBORN Clinical cyanosis is chiefly dependent on the absolute concentration of reduced hemoglobin in the blood rather than on the oxygen saturation. Thus, when there is more than 3 g of reduced hemoglobin per deciliter of arterial blood, central cyanosis should be recognizable. The O2 saturation when clinical central cyanosis becomes apparent varies from about 62% when the hemoglobin is only 8 g/dL to about 88% saturation in the polycythemic infant with a hemoglobin of 24 g/dL. The normal relative polycythemia of newborn infants (hemoglobin 14 to 20 g/dL), therefore, facilitates recognition of cyanosis. Recognition of cyanosis in the newborn is rendered more difficult by the presence of fetal hemoglobin (Fig 1). The ratio of fetal to adult hemoglobin varies from infant to infant, and the proportions of each hemoglobin affect the oxygen saturation resulting at any give Pao2. Thus, if a baby with a pH of 7.4 and a temperature of 37°C has mostly adult hemoglobin, central cyanosis (arterial saturation 75% to 85%) will be observed at a Pao2 of 42 to 53 mm Hg, whereas if the baby has mostly fetal hemoglobin, central cyanosis will be observed at a Pao2 of 32 to 42 mm Hg. Thus, the newborn with a high proportion of fetal hemogolobin may have a serious reduction in oxygen tension before central cyanosis is clinically apparent.

THE VALIDITY OF pH AND Pco2 MEASUREMENTS IN CAPILLARY SAMPLES IN SICK AND HEALTHY NEWBORN INFANTS

PEDIATRICS ◽  
1964 ◽  
Vol 34 (2) ◽  
pp. 192-197
Author(s):  
Gillian Gandy ◽  
Lotte Grann ◽  
Nicholas Cunningham ◽  
Karlis Adamsons ◽  
L. Stanley James
Keyword(s):  
Newborn Infants ◽  
Alveolar Ventilation ◽  
Capillary Blood ◽  
Acid Base ◽  
Healthy Newborn ◽  
Arterial Blood ◽  
Metabolic Component ◽  
Blood Ph ◽  
Capillary Sample ◽  
Fair Degree

This study has demonstrated that in healthy newborn infants over 3 hours of age, pH aIld Pco2 of "arterialized" capillary samples reflect closely the values of arterial blood. Prior to this age and in infants with impaired cardiopulmonary function the agreement between samples from the two sources is less satisfactory. In these infants only limited conclusions regarding acid-base state and alveolar ventilation can be drawn from capillary blood pH and Pco2. The metabolic component of acid-base disturbances can be assessed with a fair degree of accuracy even if the capillary sample is "venous" in character.

scholarly journals Correlating arterial blood gas, acid–base and blood pressure abnormalities with outcomes in COVID-19 intensive care patients

2020 ◽  
pp. 000456322097253
Author(s):  
Morne C Bezuidenhout ◽  
Owen J Wiese ◽  
Desiree Moodley ◽  
Elizna Maasdorp ◽  
Mogamat R Davids ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Intensive Care Unit ◽  
Intensive Care ◽  
Partial Pressure ◽  
Interquartile Range ◽  
Blood Gas ◽  
Partial Pressure Of Oxygen ◽  
Acid Base ◽  
Arterial Blood Gas ◽  
Arterial Blood

Background During the outbreak of coronavirus disease 2019 (COVID-19), many studies have investigated laboratory biomarkers in management and prognostication of COVID-19 patients, however to date, few have investigated arterial blood gas, acid–base and blood pressure patterns. The aim of the study is to assess the arterial blood gas and acid–base patterns, blood pressure findings and their association with the outcomes of COVID-19 patients admitted to an intensive care unit. Methods A single-centre retrospective, observational study in a dedicated COVID-19 intensive care unit in Cape Town, South Africa. Admission arterial blood gas, serum electrolytes, renal function and blood pressure readings performed on COVID-19 patients admitted between 26 March and 2 June 2020 were analysed and compared between survivors and non-survivors. Results A total of 56 intensive care unit patients had admission arterial blood gas performed at the time of intensive care unit admission. An alkalaemia (pH > 7.45) was observed in 36 (64.3%) patients. A higher arterial pH (median 7.48 [interquartile range: 7.45–7.51] versus 7.46 [interquartile range: 7.40–7.48], P = 0.049) and partial pressure of oxygen in arterial blood (median 7.9 kPa [interquartile range: 7.3–9.6] versus 6.5 kPa [interquartile range: 5.2–7.3], P = <0.001) were significantly associated with survival. Survivors also tended to have a higher systolic blood pressure (median: 144 mmHg [interquartile range: 134–152] versus 139 mmHg [interquartile range: 125–142], P = 0.078) and higher arterial HCO3 (median: 28.0 mmol/L [interquartile range: 25.7–28.8] versus 26.3 mmol/L [interquartile range: 24.3–27.9], P = 0.059). Conclusions The majority of the study population admitted to intensive care unit had an alkalaemia on arterial blood gas. A higher pH and lower partial pressure of oxygen in arterial blood on arterial blood gas analysis were significantly associated with survival.

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