Monitoring Of O2 Research Articles

Transcutaneous O2 and CO2 monitoring of high risk surgical patients during the perioperative period.

The usefulness of noninvasive transcutaneous oxygen (PtcO2) and carbon dioxide (PtcCO2) sensors as well as invasive monitoring of flow and oxygen transport were evaluated in the perioperative period of a small series of high risk surgical patients. We used the pattern of physiological events preceding intraoperative death as the criteria for evaluation of the relative usefulness of these variables. Cardiac output (CO), oxygen delivery (DO2), and O2 consumption (VO2) provided the earliest warning of impending circulatory deterioration and were most useful during critical nonlethal circulatory episodes; these were closely paralleled by the PtcO2 index (PtcO2/PaO2); the PtcCO2 was less sensitive. Heart rate (HR) and mean arterial pressure (MAP) were highly variable with frequent changes unrelated to change in flow and O2 transport.

The effect of transcutaneous Po2 monitoring on the frequency of arterial blood gas analysis in the newborn with respiratory distress.

Nineteen infants with respiratory distress and indwelling arterial lines were monitored with a transcutaneous O2 (PtcO2) monitor for 24 h each. These infants were matched with comparably sick newborns not monitored with PtcO2 and cared for in the intensive care nursery within the previous 18 months. The number of arterial blood gases (ABGs) drawn in each group was examined. Results showed that in all but 1 infant, the patients who had PtcO2 monitoring also had fewer ABGs drawn. The mean number of ABGs in the PtcO2 monitored infants was 12.5 + 2.9 (SD) and the mean number of ABGs in the non-PtcO2 monitored infants was 16.2 + 2.4. The authors conclude that supplementary O2 monitoring of sick infants with PtcO2 reduces the frequency of ABG analysis.

1364 CEREBRAL AND RETINAL HYPOPERFUSION AS A POSSIBLE CAUSE OF RETROLENTAL FIBROPLASIA – HYPOTHESIS TO EXPLAIN NON-O2 RELATED R.L.F

Retrolental fibroplasia has now been reported to occur in over 190 infants in which oxygen administration was not a factor. Ashton injected glass ballotini into kitten retinal arteries and produced vasoproliferative changes “exactly as occur in retrolental fibroplasia.” (Brit.J.Ophthal. 49:225, 1965) He demonstrated that vasoproliferation is not due to O2 toxicity per se but is “merely a sequel of the obliteration of the vessels induced by oxygen.” Our hypothesis is that R.L.F. may develop in very low birth weight infants who have cerebral/retinal hypoperfusion/ischemia, at birth or in the neonatal period. These infants have impaired cerebral blood flow autoregulation, and a high incidence (40-80%) of intracranial bleeding. This hypothesis would explain the high incidence of non-O2 related R.L.F. in anencephalic infants and the rising incidence in very low birth weight infants <1000 grams with intracranial hemorrhage. We have observed two infants with severe R.L.F., whose clinical course (asphyxia, shock, intracranial bleeding) supports our hypothesis. In one infant cerebral hypoperfusion was documented. Imperfect TcPO2 and arterial blood gas monitoring did not reveal prolonged significant hyperoxemia. Our observations suggest that hyperoxemia is not the only cause of R.L.F., cerebral hypoperfusion and retinal ischemia may produce the same picture. Careful O2 monitoring alone will probably not eliminate R.L.F.

Laser Doppler velocimetry vs heater power as indicators of skin perfusion during transcutaneous O2 monitoring.

Laser Doppler velocimetry (LDV) and heater power (HP) were compared as indicators of skin perfusion during transcutaneous oxygen tension (ptcO2) monitoring in adults. The LDV probe was fitted to a Radiometer ptcO2 attachment ring, which was fixed to the forearm. ptcO2, electrode temperature, HP, and LDV measurements were recorded continuously and simultaneously. LDV was more specific and sensitive to changes in cutaneous perfusion. Moreover, changes in perfusion were signalled four to 24 times faster by LDV than by HP. Changes in ptcO2 corresponded to changes in LDV more closely than to changes in HP in all experiments. HP was more specific and sensitive to changes in electrode and air temperatures. Once hyperemia was established at 44 degrees C and the electrode heater was turned off (HP = 0), LDV measurements frequently showed persistence of hyperemia (up to 25 min). Under these circumstances ptcO2 decreased linearly with decreasing electrode temperature in the range of 44-32 degrees C. LDV performance was referenced by monitoring velocity measurements taken on a cylinder revolving at known velocities. We conclude that LDV is a useful adjunct to ptcO2 monitoring and better than HP in assessing skin blood flow. It should enhance quality control of transcutaneous O2 monitoring.

Problems of continuous Pa, o2 monitoring by means of indwelling intra-arterial electrodes

Continuous monitoring of intra-arterial PO2 has many advantages in intensive care. However, there are some problems which have prevented the routine use of this method until now. A commercially available polarographic oxygen electrode was tested in vitro. Continuous PO2 monitoring was performed in vivo in 63 adult patients. The electrode is suitable for intensive care with regard to handling, dimensions, biocompatibility, mechanical stability, electrical safety, sensitivity, flow dependency, response time and costs. It should be improved with regard to the instability of the measuring properties and its non-linearity in hyperoxia. Serious complications of continuous PO2 monitoring were not observed. In view of the specific properties of the polarographic electrode and the contraindications of arterial cannulation, the continuous intra-arterial PO2 measurement has proved to be a valuable, safe and simple technique of monitoring, especially for short-term changes of arterial PO2.

Fabrication of electrodes for continuous tissue O2 monitoring.

ArticleFabrication of electrodes for continuous tissue O2 monitoring.J Strauss, A V Beran, and R BakerJ Strauss, A V Beran, and R BakerPublished Online:01 Dec 1974https://doi.org/10.1152/jappl.1974.37.6.988MoreSectionsPDF (723 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Download PDF FiguresReferencesRelatedInformationCited ByEffect of Norepinephrine and Angiotensin II on Intrarenal Oxygen AvailabilityErythropoietin and Intrarenal Oxygenation in Hypercapnic Versus Normocapnic HypoxemiaRelationship between Erythropoietin Levels and Intrarenal Oxygenation during Anuric Hemorrhagic Shock16 April 2012Effect of Vasopressors and Hemorrhage on Intrarenal Oxygenation More from this issue > Volume 37Issue 6December 1974Pages 988-90 https://doi.org/10.1152/jappl.1974.37.6.988PubMed4436239History Published online 1 December 1974 Published in print 1 December 1974 Metrics