A combined transcutaneous PO2-PCO2 electrode with electrochemical HCO3- stabilization

1981 ◽  
Vol 51 (4) ◽  
pp. 1027-1032 ◽  
Author(s):  
J. W. Severinghaus
Keyword(s):  
Reference Electrode ◽  
Skin Surface ◽  
Anodized Aluminum ◽  
Ph Variation ◽  
Arterial Blood ◽  
Zero Current ◽  
Cathode Current ◽  
Pco2 Electrode ◽  
Electrolyte Ph ◽  
Transcutaneous Po2

Combined transcutaneous PO2-PCO2 electrodes are described in which the interaction between the two electrodes due to OH- production at the O2 cathode has been eliminated. An anode of either anodized aluminum or platinum has been driven at a current equal to cathode current to force stoichiometric consumption of OH- at its rate of production. The AgCl reference electrode operates at zero current. O2 sensitivity was not significantly altered by electrolyte pH variation from 6.7 to 9.0 with variations by PCO2. These electrodes have been found stable both with and without spacers, and with electrolytes dissolved in 50–100% ethylene glycol. In 22 anesthetized patients, with electrode temperature of 43 degrees C (s refers to skin surface, a to arterial blood); PsO2 = 0.52PaO2 + 15 (range 54–300) (r = 0.66; Sy . x = 29.6; n = 46); and PsCO2 = 1.39PaCO2 + 2.1 (range 24–98) (r = 0.99; Sy . x = 2.28; n = 48).

Poly Silk Peptide Film PH Sensor Based on Zero Current Potentiometry

2012 ◽  
Vol 450-451 ◽  
pp. 554-556
Author(s):  
Ming Ming Ma ◽  
Zhi Tong ◽  
Yong Wen
Keyword(s):  
Graphite Electrode ◽  
Ph Sensor ◽  
Reference Electrode ◽  
Pencil Graphite Electrode ◽  
Solution Ph ◽  
Counter Electrodes ◽  
System A ◽  
Zero Current ◽  
In Series ◽  
Silk Peptide

A poly silk peptide film pH sensor has been developed using zero current potentiometry system. A poly silk peptide film coated pencil graphite electrode is connected in series between the working and counter electrodes of a potentiostat, and immersed in solution together with a reference electrode. When the solution pH varies, the resulting zero current potentiometry is linear with the values of the solution pH in the range of 1.81 to 11.58. This pH sensor shows high stability, accuracy, selectivity and reproduction.

Sensor Fused Blood Pressure Measuring Device Capable of Recording Korotkoff Sounds in Inflationary Curves

2020 ◽  
Author(s):  
Enrique Alvarez Vazquez ◽  
Daniel Ewert ◽  
Dave Jorgenson ◽  
Michael Sand
Keyword(s):  
Blood Pressure ◽  
Cuff Pressure ◽  
High Sensitivity ◽  
Skin Surface ◽  
Pressure System ◽  
Measuring Device ◽  
Arterial Blood ◽  
Pressure Cuff ◽  
System 2 ◽  
Control Electronics

Abstract This study describes a non-invasive medical device capable of measuring arterial blood pressure (BP) with a combination of inflationary and deflationary procedures. The device uses the pressure cuff pressure signal, arterial skin-surface acoustics, and photoplethysmography (PPG) to make a sensor-fusion estimation of blood pressure readings. We developed an apparatus composed of 1) a modified off-the-shelf oscillometric blood pressure system, 2) a contact microphone with an amplifier, 3) and high-sensitivity pulse oximeter, and its control electronics.

Baroreflex control of muscle sympathetic nerve activity during skin surface cooling

2007 ◽  
Vol 103 (4) ◽  
pp. 1284-1289 ◽  
Author(s):  
Jian Cui ◽  
Sylvain Durand ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Skin Surface ◽  
Surface Cooling ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Arterial Blood

Skin surface cooling improves orthostatic tolerance through a yet to be identified mechanism. One possibility is that skin surface cooling increases the gain of baroreflex control of efferent responses contributing to the maintenance of blood pressure. To test this hypothesis, muscle sympathetic nerve activity (MSNA), arterial blood pressure, and heart rate were recorded in nine healthy subjects during both normothermic and skin surface cooling conditions, while baroreflex control of MSNA and heart rate were assessed during rapid pharmacologically induced changes in arterial blood pressure. Skin surface cooling decreased mean skin temperature (34.9 ± 0.2 to 29.8 ± 0.6°C; P < 0.001) and increased mean arterial blood pressure (85 ± 2 to 93 ± 3 mmHg; P < 0.001) without changing MSNA ( P = 0.47) or heart rate ( P = 0.21). The slope of the relationship between MSNA and diastolic blood pressure during skin surface cooling (−3.54 ± 0.29 units·beat−1·mmHg−1) was not significantly different from normothermic conditions (−2.94 ± 0.21 units·beat−1·mmHg−1; P = 0.19). The slope depicting baroreflex control of heart rate was also not altered by skin surface cooling. However, skin surface cooling shifted the “operating point” of both baroreflex curves to high arterial blood pressures (i.e., rightward shift). Resetting baroreflex curves to higher pressure might contribute to the elevations in orthostatic tolerance associated with skin surface cooling.

scholarly journals Stratum Corneum Hydration and Skin Surface pH Variation Indicate that Organ Blood Flow Is Regulated by Meridian Activity at Certain Hours

2014 ◽  
Vol 2 (4) ◽  
pp. 161-172
Author(s):  
Li-Fan Chuang ◽  
Hong-Nong Chou ◽  
Chin-Kong Hsu ◽  
Hung-Shih Chou ◽  
Ping-Jyun Sung ◽  
...  
Keyword(s):  
Blood Flow ◽  
Stratum Corneum ◽  
Skin Surface ◽  
Organ Blood Flow ◽  
Surface Ph ◽  
Ph Variation ◽  
Stratum Corneum Hydration ◽  
Skin Surface Ph

Light and Transcutaneous Po2 Device = Problem?

PEDIATRICS ◽  
1986 ◽  
Vol 77 (5) ◽  
pp. 788-789
Author(s):  
MARCUS C. HERMANSEN ◽  
LAURA MOONEY ◽  
CASEY HINES
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Skin Surface ◽  
Transcutaneous Po2

To the Editor.— We would like to call attention to a recently recognized and potentially dangerous interaction of a skin surface Po2/Pco2 monitor with a phototherapy device. A five-day-old, 1,200-g infant was receiving mechanical ventilation for the treatment of respiratory failure and phototherapy for the treatment of hyperbilirubinemia. An observation was made that within a few seconds of removal of the phototherapy unit from the bedside the skin surface Pco2 would increase dramatically. If the phototherapy was then reintroduced, the Pco2 would decrease as dramatically.

Skin Oxygen Permeability in Premature Infants

PEDIATRICS ◽  
1978 ◽  
Vol 62 (4) ◽  
pp. 488-491
Author(s):  
Hans T. Versmold ◽  
Mathäus Holzmann ◽  
Otwin Linderkamp ◽  
Klaus P. Riegel
Keyword(s):  
Blood Flow ◽  
Premature Infants ◽  
Oxygen Diffusion ◽  
Oxygen Permeability ◽  
Newborn Infants ◽  
Skin Surface ◽  
The Mean ◽  
Arterial Po2 ◽  
Skin Temperatures ◽  
Transcutaneous Po2

While 24 newborn infants (ages, 2 to 48 hours; gestational ages, 24 to 42 weeks) breathed various concentrations of oxygen, the PO2 values on their unheated skin surface were measured by an unheated microcathode electrode for transcutaneous PO2 monitoring. In infants with arterial PO2 values in the range of 50 to 100 torr and with similar skin temperatures, the mean surface PO2 of unheated skin was inversely related to birth weight: 27.2 torr in infants weighing less than 1,500 gm, 14.3 torr in infants weighing 1,500 to 2,500 gm, and 2.9 torr in infants weighing more than 2,500 gm. In the smallest infants, the skin surface PO2 was significantly related to arterial P02: it was about one third of arterial PO2 as estimated by a second electrode for transcutaneous PO2 monitoring heated to 44°C. Phototherapy, crying, or blood transfusion increased the surface P02 of unheated skin, but not the tcPO2 measured at 44°C. These findings suggest that blood flow to the skin in excess of its metabolic needs due to immature control of cutaneous circulation, along with low resistance to oxygen diffusion, determines the high oxygen permeability of skin in premature infants.

Lack of Nonshivering Thermogenesis in Infants Anesthetized with Fentanyl and Propofol 

1997 ◽  
Vol 86 (4) ◽  
pp. 772-777 ◽  
Author(s):  
Olga Plattner ◽  
Margot Semsroth ◽  
Daniel I. Sessler ◽  
Angelika Papousek ◽  
Christoph Klasen ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Core Temperature ◽  
Plasma Catecholamines ◽  
Skin Surface ◽  
Infants And Children ◽  
Plasma Catecholamine ◽  
Nonshivering Thermogenesis ◽  
Arterial Blood ◽  
Plasma Catecholamine Concentrations

Background Sweating, vasoconstriction, and shivering have been observed during general anesthesia. Among these, vasoconstriction is especially important because-once triggered-it minimizes further hypothermia. Surprisingly, the core-temperature plateau associated with vasoconstriction appears to preserve core temperature better in infants and children than adults. This observation suggests that vasoconstriction in anesthetized infants may be accompanied by hypermetabolism. Consistent with this theory, unanesthetized infants rely on nonshivering thermogenesis to double heat production when vasoconstriction alone is insufficient. Accordingly, the authors tested the hypothesis that intraoperative core hypothermia triggers nonshivering thermogenesis in infants. Methods With Ethics Committee approval and written parental consent, the authors studied six infants undergoing abdominal surgery. All were aged 1 day to 9 months and weighed 2.4-9 kg. Anesthesia was maintained with propofol and fentanyl. The infants were mechanically ventilated and allowed to cool passively until core (distal esophageal) temperatures reached 34-34.5 degrees C. Oxygen consumption-the authors' index of metabolic rate-was recorded throughout cooling. Because nonshivering thermogenesis triples circulating norepinephrine concentrations, arterial blood was analyzed for plasma catecholamines at approximately 0.5 degree C intervals. Thermoregulatory vasoconstriction was evaluated using forearm-fingertip, skin-surface gradients, with gradients exceeding 4 degrees C, indicating intense vasoconstriction. The patients were subsequently rapidly rewarmed to 37 degrees C. Regression analysis was used to correlate changes in oxygen consumption and plasma catecholamine concentrations with core temperature. Results All patients were vasoconstricted by the time core temperature reached 36 degrees C. Further reduction in core temperature to 34-34.5 degrees C did not increase oxygen consumption. Instead, oxygen consumption decreased linearly. Hypothermia also failed to increase plasma catecholamine concentrations. Conclusions Even at core temperatures approximately 2 degrees C below the vasoconstriction threshold, there was no evidence of nonshivering thermogenesis. This finding is surprising because all other major thermoregulatory responses have been detected during anesthesia. Infants and children thus appear similar to adults in being unable to increase metabolic rate in response to mild intraoperative hypothermia.

In vivo thermal conductivity of the human forearm tissues

1991 ◽  
Vol 70 (6) ◽  
pp. 2682-2690 ◽  
Author(s):  
M. B. Ducharme ◽  
P. Tikuisis
Keyword(s):  
Longitudinal Axis ◽  
Skin Surface ◽  
Tissue Temperature ◽  
Bioheat Equation ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Computed Tomography Scanning ◽  
Human Forearm

The effective thermal conductivities of the skin + subcutaneous (keff skin + fat) and muscle (keff muscle) tissues of the human forearm at thermal steady state during immersion in water at temperatures (Tw) ranging from 15 to 36 degrees C were determined. Tissue temperature (Tt) was continuously monitored by a calibrated multicouple probe during a 3-h immersion of the resting forearm. Tt was measured every 5 mm from the longitudinal axis of the forearm (determined from computed-tomography scanning) to the skin surface. Skin temperature (Tsk), heat loss (Hsk), and blood flow (Q) of the forearm, as well as rectal temperature (Tre) and arterial blood temperature at the brachial artery (Tbla), were measured during the experiments. When the keff values were calculated from the finite-element (FE) solution of the bioheat equation, keff skin + fat ranged from 0.28 +/- 0.03 to 0.73 +/- 0.14 W.degrees C-1.m-1 and keff muscle varied between 0.56 +/- 0.05 and 1.91 +/- 0.19 W.degrees C-1.m-1 from 15 to 36 degrees C. The values of keff skin + fat and keff muscle, calculated from the FE solution for Tw less than or equal to 30 degrees C, were not different from the average in vitro values obtained from the literature. The keff values of the forearm tissues were linearly related (r = 0.80, P less than 0.001) to Q for Tw greater than or equal to 30 degrees C. It was found that the muscle tissue could account for 92 +/- 1% of the total forearm insulation during immersion in water between 15 and 36 degrees C.

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