Effect of bicycle racing saddle design on transcutaneous penile oxygen pressure

AIM

To determine the reliability of monitoring penile transcutaneous oxygen (tpO2) during cycling, and to assess the influence of seat design and cycling position on tpO2.

METHODS

EXPERIMENTAL DESIGN

repeated measures analysis of the effects of seat design and riding position on tpO2 values.

PARTICIPANTS

31 male cyclists between the ages of 20 and 50 years participated. Subject inclusion criteria were: averaged=or>80 miles of road bicycling per week during the 2 months prior to enrollment in this study; no history of vascular disease, diabetes, or sexual dysfunction; and had an erection within 15 days prior to study.

MEASURES

mean tpO2 values were calculated for seated and standing positions using 3 current bicycle seat designs.

RESULTS

Test-retest reliability for seated cycling tpO2 values had an ICC (3,1) of 0.76 and mean absolute difference of 5.1 mmHg. Test-retest reliability for standing cycling tpO2 values had an ICC(3,1) of 0.88 and mean absolute difference of 7.23 mmHg. No interaction effect occurred between seat design and position. Seat design had no significant effect on tpO2 values. Seated cycling significantly reduced tpO2 levels compared with standing cycling (P<0.05). Mean percent decreases in tpO2 from standing to seated cycling were; Vetta 76%, Terry 73%, and Specialized 62%.

CONCLUSION

The data suggest that penile tpO2 monitoring is reliable for use during cycling studies. None of the seats exhibited any significant ability to spare penile tpO2. The implications of decreased penile tpO2 over different time intervals on penile physiology remain to be investigated.

Simultanes nichtinvasives Monitoring mit Laser-Doppler-Flussmessung und Gewebespektrometrie bei fasziokutanen Radialislappen und osteokutanen Fibulatransplantaten

AIM

In the literature currently available monitoring devices are usually divided into two major groups: those for monitoring perfusion and those for measuring tissue oxygenation. The O(2)C (oxygen to see) system combines these two ways of monitoring free flap viability. The aim of this prospective study was to determine the necessity of flap revision and when unnecessary revision can be avoided. Another point of interest was the question of whether critical values for the successful course of free flaps could be defined and in addition whether such values would differ for different flap types.

PATIENTS AND METHODS

In a prospective study 82 free flaps (61 radial forearm flaps and 21 fibula flaps) were monitored with the O(2)C monitoring unit. Measurements were carried out intraoperatively and postoperatively up to 14 days.

RESULTS

Perfusion compromise occurred in 12 (14.6%) of 82 monitored free flaps. Operative exploration was performed in seven cases, in five of them successfully. Five flaps (three radial forearm and two fibula flaps) were lost due to vascular compromise, which led to an overall success rate of 93.4%. Venous congestion was identified by a rapid increase in hemoglobin concentration of more than 30%. An abrupt decline of blood flow and hemoglobin oxygenation indicated arterial occlusion. Vascular complications were detected in all cases prior to clinical assessment with no false positive or negative results. For radial forearm flaps a hemoglobin oxygenation of 15%, a superficial flow of 10 AU, and a deep flow of 20 AU were identified as minimum values for flap viability. For fibula flaps a hemoglobin oxygenation of 10%, a superficial flow of 5 AU, and a deep flow of 15 AU were determined as minimum values.

CONCLUSION

O(2)C combines laser Doppler flowmetry and tissue spectrophotometry and for the first time allows simultaneous measurement of the microcirculatory parameters including blood flow, flow velocity, hemoglobin concentration, and hemoglobin oxygenation. We found this new noninvasive technique to be a reliable and accurate method for evaluating flap viability and improving the success rate in free flap transfer.

Combined pulse oximetry/cutaneous carbon dioxide tension monitoring during colonoscopies: pilot study with a smart ear clip

BACKGROUND

We compared the accuracy and practicability of a new combined ear sensor device measuring pulse oximetry and transcutaneous carbon dioxide tension.

METHODS

Validation studies were done by comparing the results of the combined sensor with arterial blood gas measurements. In an observational part, monitoring data were obtained from 25 patients undergoing colonoscopy, sedated with midazolam and alfentanil and from 8 patients without sedation.

RESULTS

There was an excellent correlation between the oxygen saturation and carbon dioxide tension measurements comparing the combined sensor with arterial blood gas analysis (R 0.96 and 0.93, respectively). A mean rise in transcutaneous carbon dioxide tension of 7.6 mm Hg was detectable during sedation with midazolam/alfentanil and of 2.3 mm Hg without sedation.

CONCLUSION

Combined POX/PcCO2 monitoring at the ear lobe is a novel approach to improve patient safety during sedation and may be helpful in preventing an unintentional slide into a state of deep sedation with impairment of ventilation.

Cardiovascular aspects of septic shock: pathophysiology, monitoring, and treatment

The care of patients with septic shock is exceedingly complex. New therapies and monitoring technologies are being rapidly developed. To create an effective plan of care that integrates these new therapies and technologies, critical care nurses must understand the underlying pathophysiology of septic shock, techniques to accurately monitor patients' status, and the rationale for care.

Detection of hypoventilation during thoracoscopy: combined cutaneous carbon dioxide tension and oximetry monitoring with a new digital sensor

BACKGROUND

Changes in Paco(2) have not been described during thoracoscopy under sedation-assisted local anesthesia. We hypothesized that hypoventilation might occur secondary to administration of sedatives and decreased ventilation in one lung.

AIM

Prospectively measure cutaneous carbon dioxide tension (Pcco(2)) in addition to pulse oximetric saturation (Spo(2)) using a new combined digital sensor to examine the occurrence of hypoventilation during thoracoscopy under sedation-assisted local anesthesia.

SETTING

University hospital.

METHODS

Following validation studies, Pcco(2) was prospectively measured in 16 consecutive patients undergoing thoracoscopy under sedation-assisted local anesthesia using a combined digital earlobe sensor measuring Spo(2) (percentage) and Pcco(2) (millimeters of mercury). All patients received supplemental oxygen. Routine BP monitoring and Spo(2) was continued. Patients received IV hydrocodone, 5 mg, and intermittent boluses or IV midazolam and pethidine.

RESULTS

Mean baseline Pcco(2) measurement was 39.1 +/- 7.2 mm Hg (+/- SD) [range, 27.5 to 50.5 mm Hg], and peak measurement during the procedure was 52.3 +/- 10.3 mm Hg (range, 37.2 to 77 mm Hg) [p < 0.001]. Median and mean changes in Pcco(2) measurement from baseline were 13.0 mm Hg and 13.2 +/- 5.3 mm Hg (range, 5.5 to 27.8 mm Hg), respectively. Mean fall in Spo(2) during the procedure was 4.6 +/- 3.2% (range, 1 to 14%).

CONCLUSIONS

Thoracoscopy performed under sedation-assisted local anesthesia is associated with significant hypoventilation. Combined measurement of Spo(2) and Pcco(2) during thoracoscopy is a novel approach in the monitoring of ventilation, enhancing patient safety, and might allow to guide the administration of sedation in a better way.

Intra- und postoperatives Monitoring von Lappentransplantaten

BACKGROUND

According to Schmelzeisen et al. (1996), the failure rate for microvascular free flaps is 5%. While surface tissue oxygenation can be assessed clinically, if necessary by a puncture, the oxygen supply to deeper areas mostly cannot be checked. We therefore wished to find whether measurement of tissue pO(2) would prove to be an objective and practical technique that could be used for continuous and accurate intra- and postoperative evaluation of flap perfusion.

MATERIAL AND METHODS

A Clark-type microcatheter was used intra- and postoperatively to monitor tissue pO(2) in 5 pedicled pectoralis major flaps and 32 free revascularized flaps (9 jejunal flaps, 5 latissimus dorsi flaps, 6 radial forearm flaps and 12 scapular flaps).

RESULTS

The mean values for tissue pO(2) were significantly lower in pedicle grafts than in free revascularized flaps. Within in each flap group the pO(2) values measured did not vary significantly over an observation period of up to 77.2 h after transplantation.

CONCLUSIONS

Continuous measurement of tissue pO(2) by means of a Clark-type microcatheter combined with clinical examination constitutes a reliable method of monitoring tissue oxygenation in pedicle grafts and free revascularized flaps during the intra- and postoperative phases. Analysis of small and of wide fluctuations in pO(2) values may help in the diagnosis of early arterial and venous obstructions in flaps and may in the future result in new insights into the tissue oxygenation in surgical flaps allowing some alleviation of the problems currently experienced in clinical monitoring.

Forehead SpO2 monitoring compared to finger SpO2 recording in emergency transport

Continuous peripheral oxygen saturation monitoring using a finger pulse oximeter is standard in prehospital emergency medicine. Forehead peripheral oxygen saturation monitoring has been enhanced for better performance during movement and in cold ambient temperatures, both of which are common during emergency transport. We compared a new forehead monitor with standard finger pulse oximeter. The forehead technique had significantly fewer mean (SD) alarms per patient (3.0 (2.2)) than the finger pulse oximeter (7.8 (4.0)) and shorter durations of malfunction (76 (60) s compared to 333 (170) s) when using the finger pulse oximeter. We conclude that measuring peripheral oxygen saturation monitoring with a forehead sensor provides better monitoring quality in emergency care.

[Intraoperative detection of ischemic brain hypoxia using oxygen tissue pressure microprobes]

OBJECTIVE AND IMPORTANCE

Detection of intraoperative ischemic events could lead to the resolution of their cause and to the prevention of the definitive establishment of a postoperative infarct. We want to illustrate the possibilities that intraoperative monitoring of oxygen tissue pressure (PtiO2) in critical areas during a neurosurgical vascular procedure offers, enhancing its reliability and immediacy in obtaining information about tissue oxygenation status as a marker of ischemia in the vascular territory at risk.

CLINICAL PRESENTATION

We report the case of a 32 year-old male with a deep arteriovenous malformation (AVM) localised in the insular region. The patient had been previously treated with radiosurgery without achieving a satisfactory result.

INTERVENTION

AVM removal was performed through a transylvian transinsular approach. PtiO2 was monitorised at the temporal pole (reference area) and at the posterior temporal region (risk area). Both probes maintained close tissue oxygenation levels until the last stage of the AVM resection when, during the coagulation of a supposed afferent vessel, a brisk fall of the oxygen tissue pressure in the posterior temporal region was detected. An ischemic infarct in this area was observed postoperatively.

CONCLUSIONS

PtiO2 monitoring has a high reliability in the detection of intraoperative tissue hypoxia. Data obtained could lead to early identification of these events and, whatever possible, to resolve this situation preventing the definitive establishment of an ischemic infarct.

Transcranial Doppler and Near-Infrared Spectroscopy Can Evaluate the Hemodynamic Effect of Carotid Artery Occlusion

Background and Purpose— Cerebral hemodynamic and metabolic changes can compensate for the decrease in cerebral blood flow occurring in patients with carotid occlusive disease. At present, a complete assessment of the cerebral adaptive status is only possible with positron-emission tomography. Near-infrared spectroscopy (NIRS) is a noninvasive technique that, providing a real time assessment of fluctuations in cerebral hemoglobin, has been used to estimate the cerebral blood volume and to measure cerebral vasomotor reactivity (VMR). Moreover, NIRS technology, by allowing the absolute measurement of absorption and scattering coefficients of brain, can determine the oxyhemoglobin and deoxyhemoglobin concentrations in situ in the blood stream.

Methods— In order to evaluate different aspects of the cerebral hemodynamic status, 27 subjects with symptomatic and asymptomatic carotid artery occlusion and 30 healthy subjects underwent a simultaneous examination by means of transcranial Doppler (TCD), able to reliably detect collateral circulation and VMR, and NIRS at rest condition and during CO 2 reactivity test.

Results— The main finding of this study was the demonstration of a difference between asymptomatic and symptomatic patients in terms of mean flow velocity increase (52.4% versus 21.0%; P <0.001) estimated by TCD and of hemoglobin saturation increase measured by NIRS (6.8% versus 3.8%; P =0.015).

Conclusions— The opportunity to perform NIRS and TCD simultaneously provides useful information about both hemodynamic and metabolic cerebral adaptive status in patients with occlusive disease in a simple, noninvasive, and reliable way.

Evaluation of a new combined SpO2/PtcCO2 sensor in anaesthetized paediatric patients

BACKGROUND

The recently introduced TOSCA monitor (Linde Medical Sensors AG, Basel, Switzerland) combines pulse oximetry (SpO2) and transcutaneous PCO2 (PtcCO2) monitoring in a single ear sensor. The aim of the present study was to evaluate accuracy of the TOSCA monitor to estimate SaO2 and PaCO2 in anaesthetized children.

METHODS

With approval of the hospital ethical committee and after obtaining informed parental consent, the TOSCA sensor was attached to one ear lobe of anaesthetized children in whom arterial access was established for cardiac catheterization or invasive blood pressure monitoring. SpO and PtcCO2 as well as SpO and PECO2 values from the anaesthesia monitoring (AS5; Datex-Ohmeda, Helsinki, Finland) were compared with SaO2 and PaCO2 values from arterial blood gas analysis. Corresponding data were compared using Bland Altman bias analysis.

RESULTS

A total of 111 blood samples were taken from 60 children (median age: 4.41 years; 0.35-16.13 years). SaO2 values ranged from 63 to 100% (median: 98.7%), PaCO2 ranged from 3.8 to 7.3 kPa (median: 4.6 kPa). Mean difference (+/-2 sd) between PaCO2 and PtcCO2 was -0.035 kPa (+/-0.74 kPa), between PaCO2 and PECO2 0.002 kPa (0.73 kPa), respectively (1 kPa = 7.3 mmHg). Bias and precision between SaO2 and SpO was -0.63% (+/-2.77%) and 0.13% (+/-4.52%) between SaO2 and SpO.

CONCLUSIONS

In anaesthetized children, the TOSCA ear sensor allows estimation of SaO2 and PaCO2, comparable in accuracy to endtidal capnometry and finger pulse oximetry. This makes the TOSCA monitor a helpful add-on to respiratory monitoring in anaesthetized children, in situations, in which endtidal capnometry is unreliable or difficult to establish.

[Monitoring oxygen saturation in the pediatric population]

Pulsoxymetry is noninvasive technique which is in use for percentage estimation of hemoglobin saturation of oxygen in arterial blood. It represents a therapeutical screening of treatment in paediatric population. The aim of this retrospective study is to evaluate the validity of noninvasive technique for determination of oxygen concentration in cardiac and pulomological patients. The study included 221 patients, with a mean age of 39 months (1.5-192) who were hospitalised during the period of 1.6.2000. till 31.12.2002. at Pulmoalergology and Cardiorheumatology department of Paediatric clinic CCU Sarajevo. Three groups of patients were evaluated: first one, which included 194/221 patients with obstructive and inflammatory lung diseases, 17/221 patients formed II group of pts with congenital heart anomalies (CHA) and the third one which had 10/221 patients with CHA associated with lung diseases. In all patients the diagnostic-laboratory investigations were done including transcutaneous determination of oxygen saturation by pulsoxyimetry (PO) Nellcor and Johnson-Johnson, as well as capillary, with adequate treatment. The mean oxygen saturation (OS) in the first group of patients at admission by PO was 86%, capillary 73.6%, and after treatment OS PO was 91.6%. In the II group the mean OS at admission was 88.5% PO, capillary 83%, after treatment 94.9%. The mean OS at admission in third patient's group was 76%, and after treatment 91.2% which is statistically significant (F = 0.03) and is in concordance with modern therapeutical approach. Pulseoxymetry is noninvasive, painless, simple method which offers a valid continuous data needed for the adequate choice of treatment in paediatric patients.

Screen-printed transcutaneous oxygen sensor employing polymer electrolytes

A disposable, transcutaneous oxygen sensor has been designed and implemented using screen-printing technology for all fabrication stages. The sensor incorporates an integral heating element to promote transcutaneous diffusion of blood gases so that a reliable estimation of arterial blood gas concentration can be obtained. The oxygen sensing part of the device consists of a screen-printed Clark cell implemented as electrodes, electrolyte and membrane. A three-electrode configuration is employed with gold working and counter electrodes and a silver/silver chloride reference electrode. Several different polymer electrolyte and membrane materials were evaluated in the construction of the device, and their performances were compared. A fully automated gas testing rig was constructed to enable oxygen levels to be varied under computer control. Cyclic voltammetry and static analysis of the sensors were carried out at different oxygen concentration levels and in various test environments. Linear relationships were established with an averaged sensitivity level of 0.02 microA(mmHg)(-1) and high regression coefficients of 0.99. The prototype covered with a polytetrafluoroethylene membrane gave the experimental result of I (microA) = -0.025PO2 (mmHg) - 0.085. Several factors influenced the performance of the sensors. The investigations have greatly contributed towards an understanding of the suitability of the materials in achieving a viable, low-cost sensor.

New desaturation index to evaluate neonatal apnea using polygraphy

BACKGROUND

Polygraph recordings of neonatal apnea obtained using an Eden Trace II monitor were manually analyzed to devise a new desaturation index (DSI).

METHODS

Heart rate, thoracic respiratory movements, airflow, and blood oxygen saturation (SpO2) of 25 neonates in intensive care were monitored using polygraphy. The DSI was defined as the number of SpO2 decreases per hour of valid monitoring time. Neonates were divided into three groups according to DSI85: group A, DSI85 less than one decrease per hour (n = 12); group B, DSI85 ranging from one to nine decreases per hour (n = 8); and group C, DSI85 > or=10 decreases per hour (n = 5). Clinical characteristics and type of apnea in each group were compared statistically. Group C neonates were treated with aminophylline, and the effects of treatment were evaluated.

RESULTS

Gestational age at birth, birthweight, age at monitoring and valid monitoring time did not differ significantly between the three groups, but mean SpO2, DSI70, the frequency of central apnea and periodic breathing did. Oxygen desaturation in group B and particularly group C was predominantly attributable to periodic breathing rather than central apnea. Aminophylline produced significant improvement in periodic breathing but exerted no significant effect on the other types of apnea. Both DSI85 and DSI70 were strongly correlated (r = 0.833).

CONCLUSIONS

Polygraphic study of neonates at risk revealed marked arterial oxygen desaturation, even among those with periodic breathing. This novel DSI represents a useful tool for evaluating apnea and periodic breathing in neonates and for assessing treatment efficacy.

Pulsioximetría y capnografía

Noninvasive methods of monitoring are crucial in the management of intensive care patients, especially in the pediatric field. Pulse oxymetry measures arterial oxygen saturation in severely ill patients, allows oxygen requirements to be adjusted to the patient, reduces invasive gasometric studies and achieves continuous monitoring of the critically ill child. Motion and deficient tissular perfusion reduce the accuracy of the measured values, but more sophisticated pulse oximeters are more effective in preventing these artifacts. Capnometers are an excellent method of measuring end-tidal CO2 values in real time in intubated patients. Capnography produces a graphic curve of end-tidal CO2 while capnometry provides a numerical representation of this concentration. This technique is highly useful in the continuous monitoring of various respiratory problems and situations such as weaning or checking the correct placement of endotracheal cannulas.

Medical devices; reclassification of the cutaneous carbon dioxide and the cutaneous oxygen monitor. Final rule

The Food and Drug Administration (FDA) is reclassifying the cutaneous carbon dioxide (PcCO2) monitor from class II (performance standards) into class II (special controls). FDA is also reclassifying the cutaneous oxygen (PcO2) monitor for an infant patient who is not under gas anesthesia from class II (performance standards) into class II (special controls) and is reclassifying the cutaneous oxygen (PcO2) monitor for all other uses from class III (premarket approval) into class II (special controls). Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document entitled "Class II [[Page 76679]] Special Controls Guidance Document: Cutaneous Carbon Dioxide (PcCO2) and Oxygen (PcO2) Monitors; Guidance for Industry and FDA" that will serve as the special control for the devices. These reclassifications are taken on the agency's own initiative based on new information. These actions are being taken under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990 (the SMDA), the Food and Drug Administration Modernization Act of 1997 (FDAMA), and the Medical Device User Fee and Modernization Act.

[Transcutaneous carbon dioxide and oxygen measurement in patients undergoing microlaryngosurgery with high frequency jet ventilation]

BACKGROUND

High frequency jet ventilation (HFJV) via thin tracheal tube is a convenient method of ventilation in microlaryngosurgery, but the problem of the assessment of oxygen and carbon dioxide status during HFJV is yet to be studied.

METHODS

Fifteen patients undergoing microlaryngosurgery under total intravenous anesthesia with HFJV were studied. The combined transcutaneous carbon dioxide (PtcCO2) and oxygen (PtcO2) levels were compared with arterial blood gas values (PaCO2, PaO2).

RESULTS

The PtcCO2 values demonstrated a high degree of correlation with PaCO2 before intubation (r = 0.97), during HFJV (r = 0.96), and after anesthesia (r = 0.93). The PaO2 values demonstrated a generally good correlation with PaO2 before intubation (r = 0.78) and during HFJV (r = 0.83), but not after anesthesia (r = 0.54).

CONCLUSION

Capnography values are invalid during HFJV, and an arterial catheter is not always indicated and feasible in microlaryngoscopy. The transcutaneous devices provide an effective method for non-invasive monitoring of PaCO2 in situations where continuous and precise control of CO2 levels is desired such as in perioperative period of microlaryngosurgery with HFJV.

Visible reflectance hyperspectral imaging: characterization of a noninvasive, in vivo system for determining tissue perfusion

We characterize a visible reflectance hyperspectral imaging system for noninvasive, in vivo, quantitative analysis of human tissue in a clinical environment. The subject area is illuminated with a quartz-tungsten-halogen light source, and the reflected light is spectrally discriminated by a liquid crystal tunable filter (LCTF) and imaged onto a silicon charge-coupled device detector. The LCTF is continuously tunable within its useful visible spectral range (525-725 nm) with an average spectral full width at half-height bandwidth of 0.38 nm and an average transmittance of 10.0%. A standard resolution target placed 5.5 ft from the system results in a field of view with a 17-cm diameter and an optimal spatial resolution of 0.45 mm. The measured reflectance spectra are quantified in terms of apparent absorbance and formatted as a hyperspectral image cube. As a clinical example, we examine a model of vascular dysfunction involving both ischemia and reactive hyperemia during tissue reperfusion. In this model, spectral images, based upon oxyhemoglobin and deoxyhemoblobin signals in the 525-645-nm region, are deconvoluted using a multivariate least-squares regression analysis to visualize the spatial distribution of the percentages of oxyhemoglobin and deoxyhemoglobin in specific skin tissue areas.

[Continuous free-flap monitoring with tissue-oxygen measurements: experiences of the last years]

Early recognition of flap failure is the prerequisite for flap salvage. Many methods are used to monitor free-flaps. The time interval for re-establishing vascular patency is the deciding factor for a successful revision. Prompt revision surgery and a quick and sufficient correction of the microvascular anastomosis are necessary to reestablish flap viability. The aim of this study was to evaluate the real impact of this probe as a continuous, precise and clinically relevant monitoring system in free-flap surgery. One of our main objectives was to create guidelines and "normal" ranges of p ti O 2 -values for the uncomplicated use of the Licox Probe in free-flap surgery for the first time. The Licox Catheter pO 2 Mikro-Probe instrument is used for continuous determination of oxygen partial pressure (pO 2 ) in body fluids and tissue (p ti O 2 ). Over a period of more than three years, 70 free tissue-transplantations to the head and neck, trunk, and upper and lower extremities were monitored by use of the implantable Licox Catheter Probe System. In all patients, a decrease of the p ti O 2 -levels was noted during the first minutes, until a more or less stable level was reached. At the time of weaning off, the p ti O 2 values decreased once again. After approximately 30 minutes, an almost stable but reduced p ti O 2 -level was reestablished (34,6 +/- 10,9 mm Hg). During the next days, we observed a more or less constant but reduced level. These values from the second day on were lower than the mean values of the first day. The mean value for all flaps was 23,1 +/- 6,5 mm Hg. Nevertheless, in all cases (10 of 70 flaps) where the p ti O 2 -level decreased more than 10 mm Hg within a half hour period, the flap showed vascular problems on re-exploration. Another clinically relevant value that was observed in all flaps with vascular problems was a drop of the p ti O 2 -value, below 10 mm Hg. In the cases of arterial thrombosis (2 of 10 flaps), a rapid decrease was noted. In the cases of venous complications (8 of 10 flaps), a more or less slow decrease of the p ti O 2 -value was observed. These observations may serve as precise indicators for vascular complications and flap failure. Based on our observations and data, it seems that the Licox-Probe is a sensitive and accurate monitoring system for a variety of free flaps.

Transcutaneous blood gas monitoring in the rat

Transcutaneous blood gas (TCBG) analysis is a noninvasive alternative method of estimation of blood gas tensions. The objective of the study reported here was to validate this method against standard blood gas (STBG) analysis in adult and juvenile Sprague-Dawley rats. We sought to establish the optimal TCBG probe site and temperature, to establish probe temperatures that would not cause thermal burns, to evaluate correlations between blood gas values (PaCO2 and PaO2) determined by use of TCBG and STBG, and to evaluate the sensitivity of the TCBG unit to changes in arterial blood gas partial pressures. Our results indicated that: in general, the xyphoid area was the optimal site for probe placement, with 44.5 degrees C being the optimal probe temperature for the highest correlation, but thermal burns may be a problem; probe temperatures of 42.5 degrees C (adults) and 42.0 degrees C (juveniles) do not cause thermal burns when left in place for three hours; probe temperatures of 44 degrees C (adults) and 42 degrees C (juveniles) resulted in moderate correlation between PaCO2 and PtcCO2; and the TCBG unit adequately responded to changes in arterial blood gas partial pressures. Neither PtcCO2 or PtcO2 reflect actual values of PaCO2 or PaO2, respectively. We concluded that TCBG analysis may be used as an indicator of change in PaCO2 with sufficient animal numbers under tightly controlled conditions, but not as an indicator of change in PaO2 in adult and juvenile rats.

Impact of inspired gas mixtures on preoperative infants with hypoplastic left heart syndrome during controlled ventilation

BACKGROUND

Management strategies for preoperative infants with hypoplastic left heart syndrome (HLHS) include increased inspired nitrogen (hypoxia) and increased inspired carbon dioxide (hypercarbia). There are no studies directly comparing these 2 therapies in humans. This study compares the impact of hypoxia versus hypercarbia on oxygen delivery, under conditions of fixed minute ventilation.

METHODS AND RESULTS

Ten anesthetized and paralyzed preoperative infants with HLHS were evaluated in a prospective, randomized, crossover trial comparing hypoxia (17% FIO(2)) with hypercarbia (2.7% FICO(2)). Each patient was treated in a random order (10 minutes per condition) with a recovery period (15 to 20 minutes) in room air. Arterial (SaO(2)) and superior vena caval (SvO(2)) co-oximetry and cerebral oxygen saturation (ScO(2)) measurements were made at the end of each condition and recovery period. ScO(2) was measured by near infrared spectroscopy. Hypoxia significantly decreased both SaO(2) (-5.2+/-1.1%, P=0.0014) and SvO(2) (-5.6+/-1.7%, P=0.009) compared with baseline, but arteriovenous oxygen saturation (AVO(2)) difference (SaO(2)-SvO(2)) and ScO(2) remained unchanged. Hypercarbia decreased SaO(2) (-2.6+/-0.6%, P=0.002) compared with baseline but increased both ScO(2) (9.6+/-1.8%, P=0.0001) and SvO(2) (6+/-2.2%, P=0.022) and narrowed the AVO(2) difference (-8.5+/-2.3%, P=0.005). Both hypoxia and hypercarbia decreased the balance between pulmonary and systemic blood flow (Qp:Qs) compared with baseline.

CONCLUSIONS

In preoperative infants with HLHS, under conditions of anesthesia and paralysis, although Qp:Qs falls in both conditions, oxygen delivery is unchanged during hypoxia and increased during hypercarbia. These data cannot differentiate cerebral from systemic oxygen delivery.

Performance of transcutaneous PCO2 and pulse oximetry monitors in newborns and infants after cardiac surgery

We examined the effect of core and skin temperature on the accuracy of two pulse oximeters (Nellcor Symphony and Hewlett Packard saturation module, M1020A) and a transcutaneous PCO2 monitor (Fastrac Transcutaneous monitor) immediately after cardiac surgery in a group of newborns and infants. Seventy-nine sets of data were collected from 46 patients. Core temperatures ranged from 35.3 degrees C to 39.4 degrees C, skin temperatures ranged from 27.0 degrees C to 37.4 degrees C and core-skin temperature gradients ranged from 0.1 degree C to 10.1 degrees C. Data analysis consisted of comparing the difference between transcutaneous PCO2 and arterial PCO2 and the differences between oxygen haemoglobin saturation measured by both pulse oximeters and oxygen haemoglobin saturation measured by co-oximeter to core temperature, skin temperature and core-skin temperature gradients. The mean differences +/- standard deviations and limits of agreement for transcutaneous PCO2 and oxygen haemoglobin saturation measured by the Hewlett Packard and Nellcor pulse oximeters were 0.95 +/- 4.10 mmHg (-7.09 mmHg to 8.99 mmHg), -1.07 +/- 1.84% (-4.68% to 2.54%) and -1.23 +/- 2.23% (-5.60% to 3.14%) respectively. Analysis of correlation coefficients showed that the accuracy of the transcutaneous PCO2 monitor and the pulse oximeters were not affected by core temperature, skin temperature or core-skin temperature gradient in the ranges encountered. We therefore conclude that these devices are acceptably accurate and suitable for use in infants when core and skin temperatures and core-skin temperature gradient are in the range normally found after cardiac surgery.

[Blood glucose measurement]

For all diabetic patients in which the blood glucose is unstable, self-monitoring of blood glucose (SMBG) is effective. Especially, the patient who insulin supplies are necessary is indispensable SMBG in spite of tyep 1 and/or type 2 diabetes mellitus. SMBG measuring devices of looked forward nothing noninvasive type entered the practical stage. For example, the patient who requires the frequent measurement can be applied to alarms of the hypoglycemia unawareness, etc. from present performance, because blood glucose monitoring in the any time possible, though changing in taking in SMBG measuring device of the conventional invasive type, is not possible. And, it is possible to utilize in health care and protective measurement of the lifestyle related disease, etc., because the daily observation of the blood glucose is carried out in the long term. The function of data assist center, etc. is expected these this data for processing through the internet, etc. and follow of the result.