Transcutaneous carbon dioxide monitoring in the newborn period

One hundred ninety-one simultaneous PtcCO2 and PaCO2 values were recorded from 20 neonates using a heated CO2 sensor. Gestational age and birth weight ranged from 30--44 weeks and 1.22--3.4 kg, respectively. An overestimation of PaCO2 was consistently found. Regression analysis revealed a slope of 1.29, an intercept of 18 mm Hg and a correlation coefficient of 0.85 (p less than 0.001). The PtcCO2 sensor has multiple potential uses in the sick neonate but further experience is necessary to provide adequate correction factors.     

Transcutaneous carbon dioxide monitoring during neonatal transport

We studied the value of transcutaneous carbon dioxide (PtcCO2) monitoring during neonatal transport. Thirty-two neonates with respiratory distress were alternately enrolled in an experimental group (results of PtcO2 and PtcCO2 available for clinical management) and a control group (results of only PtcO2 available). Although differences were not significant, infants in the experimental group had more changes in the intermittent mandatory ventilation (IMV) settings during transport, and more such infants arrived at the receiving hospital with acceptable pH and PCO2 values. On arrival at the receiving hospital, two patients in the control group had acidosis and hypercarbia and were placed on IMV immediately on arrival. No such patients were encountered in the experimental group. For patients needing IMV during transport, the percentage of study time spent with PtcCO2 measurements in the normal range (35 to 45 torr) was greater for the experimental group (p less than .02). Continuous PtcCO2 monitoring during transport offers the opportunity to further decrease the risks of transporting a critically ill neonate.     

Current concepts in the treatment of bacterial meningitis beyond the neonatal period

The epidemiology and treatment approach to bacterial meningitis has changed dramatically since the advent of antimicrobial therapy. New vaccines against meningeal pathogens have been implemented into national immunization programs successfully around the world. Antibiotic resistance has had a considerable impact on the efficacy of several therapeutic agents. In this review, the authors will discuss the principles of antibiotic chemotherapy, focusing on new agents for the treatment of penicillin-resistant pneumococci and adjunctive treatments to reduce the inflammatory response to bacterial infection of the meninges.     

Transcutaneous respiratory electromyographic monitoring

The integrated diaphragm electromyogram (EMG) signal reflects function from the inspiratory centers to the neuromuscular junction. The feasibility and potential value of transcutaneous diaphragm electromyography (tcEMG) was confirmed in a group of infants using two prototype respiratory EMG monitors. Infants were monitored continuously for periods ranging from hours to days. One hundred were monitored for clinical reasons, looking for disordered respiratory behavior, while 47 were studied for technical/experimental reasons. Reliable measurements of diaphragm EMG activity were obtained, provided fully shielded electrode cables were used. Measurements in 28 ventilated infants and one adult confirmed that, unlike impedance and other non-electrophysiologic measures, tcEMG monitoring is not contaminated by ventilator-induced respiratory movements. The potential value of tcEMG monitoring in ventilated subjects is exemplified by illustrations of: diaphragmatic inactivity from phrenic nerve injury, inadequate central drive, and neuromuscular block; augmented expiratory muscle activity; and progressive increase in inspiratory diaphragmatic activity in the presence of a tension pneumothorax. TcEMG monitoring should prove a worthwhile addition to the available noninvasive respiratory monitoring techniques.     

Transcutaneous carbon dioxide monitoring

Technologies now exist that measure carbon dioxide levels transcutaneously. Rapid assessment of patients who have depressed ventilation or suspected sepsis can improve treatment decisions including the need for admission to the ICU and pulmonary artery catheterization.     

Continuous polarographic monitoring of intra-arterial oxygen in the perioperative period

Intra-arterial PO2 (PiO2) was polarographically monitored in ten critically ill patients during induction of anesthesia, the intraoperative period, extubation, and the immediate postoperative period; 147 PiO2 values were then paired with simultaneous measurements of PaO2. Mean PiO2 closely followed mean PaO2 over a wide range of values (r = .97), and the continuous, online real-time PiO2 readings provided a useful early warning system for hypoxemia during crisis periods. Technical problems included catheter clotting from improper flushing, changes in PiO2 due to changes in body temperature, the need for in vitro and in vivo calibration, and sensor drift. However, these problems were resolved by appropriate catheter management and sensor calibration.     

Transcutaneous oxygen tension monitoring in critically ill patients receiving packed red blood cells

Purpose

Whether transfusions of packed red blood cells (PRBCs) affect tissue oxygenation in stable critically ill patients is still matter of discussion. The microvascular capacity for tissue oxygenation can be determined noninvasively by measuring transcutaneous oxygen tension (tcpO₂). The aim of this study was to assess tissue oxygenation by measuring tcpO₂ in stable critically ill patients receiving PRBC transfusions.

Methods

Nineteen stable critically ill patients, who received 2 units of PRBC, were prospectively included into this pilot study. Transcutaneous oxygen tension was measured continuously during PRBC transfusions using Clark's electrodes. In addition, whole blood viscosity and global hemodynamics were determined.

Results

Reliable measurement signals during continuous tcpO₂ monitoring were observed in 17 of 19 included patients. Transcutaneous oxygen tension was related to the global oxygen consumption (r = − 0.78; P = .003), the arterio-venous oxygen content difference (r = − 0.65; P = .005), and the extraction rate (r = − 0.71; P = .02). The transfusion-induced increase of the hemoglobin concentration was paralleled by an increase of the whole blood viscosity (P < .001). Microvascular tissue oxygenation by means of tcpO₂ was not affected by PRBC transfusions (P = .46). Packed red blood cell transfusions resulted in an increase of global oxygen delivery (P = .02) and central venous oxygen saturation (P = .01), whereas oxygen consumption remained unchanged (P = .72).

Conclusions

In stable critically ill patients, microvascular tissue oxygenation can be continuously monitored by Clark's tcpO₂ electrodes. According to continuous tcpO₂ measurements, the microvascular tissue oxygenation is not affected by PRBC transfusions.     

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.     

Continuous monitoring of mixed venous oxygen in neonatal pulmonary hypertension

The management of persistent fetal circulation (PFC) in 3 neonates was facilitated by continuous monitoring of either pulmonary artery (PAP) or right ventricular pressure using an umbilical catheter with a catheter-tip electrode. The catheter was inserted without fluoroscopy via the umbilical vein, using continuously monitored oxygen tension and pressure waveform to determine entry into the right ventricle in 1 patient and the main pulmonary artery in 2 others. Right ventricular and PAP responses to dopamine, dobutamine, and tolazoline facilitated pharmacologic management, whereas continuous mixed venous oxygen tension (PVO2) provided an index of tissue oxygenation.     

Transcutaneous monitoring of oxygen tension in patients with chronic obstructive lung diseases undergoing physical loading

Noninvasive monitor-aided transcutaneous determination of oxygen tension--TcPO2 (oxymonitor SM 361, Hellige, FRG) was performed in 32 patients aged 34 to 70 with chronic obstructive pulmonary diseases (COPD) during bicycle ergometry testing of moderate power (300 kgm/min) for 5 min. Respiration biomechanics was investigated before testing in all the patients using the method of total plethysmography (Pulmorex, Fenyves Gut, Switzerland). During testing all the patients were divided into 2 groups with relation to variations of TcPO2 values. A conclusion was made that the type of TcPO2 changes during exercise testing of COPD patients gave an opportunity for distinguishing between different types of bronchial obstruction.     

Transcutaneous monitoring during high-frequency jet ventilation

Simultaneous transcutaneous PO2 (PtcO2) and PCO2 (PtcCO2) recordings, done on a patient during high-frequency jet ventilation (HFJV) in thoracic surgery, reflected exactly PaO2 and PaCO2 changes induced by surgical manipulation and by ventilator setting alterations. PtcO2 and PtcCO2 monitoring with a single sensor was valuable during HFJV for the early detection of acute changes in the efficacy of gas exchange and for the correction of the ventilator setting.     

经皮血氧饱和度测定对游离皮瓣移植后血管危象动态监测的实验研究

目的评价经皮血氧饱和度(SPO2)监测法在动态监测游离皮瓣移植后血管危象中的作用。方法30只新西兰兔制作双侧下腹部腹壁浅动脉皮瓣模型,随机分为3组:动脉阻断组,静脉阻断组,动静脉阻断组。阻断及复通血管,动态测定皮瓣经皮SPO2,并与皮瓣颜色、温度变化时间作比较。结果动脉阻断后(106±37)s皮瓣经皮SPO2降至最低阈值,复通后(178±17)s回升达到正常水平。静脉阻断后,皮瓣SPO2开始表现为紊乱和波动,(198±26)s后SPO2达到最低阈值,复通后(635±37)s平缓回升到正常水平。静脉阻断组的下降和回升的时间差明显长于动脉阻断组(P<0.01)。全血管阻断后SPO2下降时间与复通时间与动脉阻断组相似。皮瓣温度、颜色的变化时间明显长于皮瓣SPO2变化时间。结论经皮的SPO2监测法能够早期敏感、客观和快捷反映皮瓣的灌注情况,是游离皮瓣血管危象动态监测的理想手段之一。     

Transcutaneous oxygen tension measurements in the assessment of limb ischaemia

Summary. The measurement of transcutaneous oxygen tension (TcPo₂) has been adapted for the assessment of the blood supply of the lower limb. This study was undertaken to determine the most useful means of expressing TcPo₂ measurements. We studied 176 patients with peripheral vascular disease and/or diabetes and 34 normal volunteers. Approxiately half of the patients studied had ulceration or gangrene of the foot. A comparison of three methods of expressing TcPo, measurement for predicting presence of ulceration was made using ROC A analysis. The absolute value of TcPo, on the dorsum of the foot was the best predictor of the presence of ulceration or gangrene. An absolute value of TcPo, of 30 mmHg on the dorsum of the foot had a sensitivity of 42% and specificity of 91%. The sensitivity of the test was as good in diabetic patients as in non-diabetic patients.