Factors affecting heated transcutaneous PO2 and unheated transcutaneous PO2 in preterm infants

The authors evaluated transcutaneous PCO2 (PtcCO2) and PO2 (PtcO2) electrodes in 25 infants. Their diagnosis were severe hyaline membrane disease (HMD) (18), aspiration syndrome (3), severe hydrops, (3) persistent fetal circulation (6), and the others, congenital pneumonia, congenital plural effusion, pulmonary hemorrhage. In most all, the cardiovascular system was compromised, i.e., PDA with congestive heart failure and shock. PtcO2 electrode was heated to 43.5 degrees C while PtcCO2 electrode was not heated. Simultaneous arterial blood pressure (ABP), pH, arterial blood gases were obtained with the transcutaneous gas measurements. The data were analyzed first dividing all the paired arterial and transcutaneous gas tensions into those with and without cardiovascular drugs (dopamine, isoproterenol), and second, the paired values were divided into those taken (a) during severe acidosis (pH less than 7.25), (b) hypotension (less than 2 SD) of normal, and (c) hypotension and acidosis. These data show: (1) the unheated PtcCO2 and heated PtcO2 accurately correlated with the simultaneous arterial measurements: (2) PtcCO2 reflects tissue PCO2; (3) drugs affect both the PtcCO2 and PtcO2; (4) elevated PtcCO2 dissociating from the simultaneous PaCO2 in neonates with cardiovascular compromise results from decreased tissue perfusion. These data suggest that transcutaneous gas sensors perform dual functions; first, as gas monitors in patients without cardiovascular alterations, and second, in patients with cardiovascular compromise, PtcCO2 reflected tissue perfusion and PtcCO2 monitored oxygen delivery to the tissues.     

Comparison of arterial blood gas with continuous intra-arterial and transcutaneous PO2 sensors in adult critically ill patients

We compared the partial pressure of oxygen directly via a continuous intra-arterial probe (PiaO2) and indirectly using a transcutaneous device (PtcO2) with simultaneously obtained arterial blood PaO2. The PiaO2 values were measured using a bipolar oxygen sensor placed through an 18-ga arterial catheter. The PtcO2 values were measured using a transcutaneous O2-CO2 sensor placed on the abdomen. Seven critically ill, hemodynamically stable, ventilator-dependent adult patients were studied. Measurements were obtained at varying concentrations (0.25 to 1.0) of inspired oxygen after a 10-min stabilization. A total of 78 simultaneous values were obtained; by linear regression: PiaO2 = 0.91 PaO2 + 1.39 (r = .98, standard errors of the estimate [SEE] = 18.6); PtcO2 = 0.39 PaO2 + 36.2 (r = .89, SEE = 14.1). To assess these instruments as trend monitors, we compared the changes in simultaneous PaO2, PiaO2, and PtcO2 values; by linear regression: delta PiaO2 = 0.90 delta PaO2 + 3.88 (r = .96, SEE = 27.7); delta PtcO2 = 0.43 delta PaO2 + 5.6 (r = .94, SEE = 15.2). We conclude that, although these instruments correlate highly with the PaO2, the SEE was substantial and therefore may limit their clinical reliability in adults. Any acute or clinically significant change in PiaO2 or PtcO2 should be confirmed with a blood gas PaO2.     

Is transcutaneous PO2 monitoring during exercise a reliable alternative to arterial PO2 measurements?

Summary. Arterial PO₂ measurement during exercise is an important part in the evaluation of pulmonary disease but requires an intra-arterial cannula. However, in clinical work it would be preferable to assess PO₂ non-invasively. To evaluate such a technique, simultaneous measurements of transcutaneous PO₂ (tcPO₂) and arterial PO₂ (PaO₂), sampled from an indwelling arterial radial cannula, were made before, during and after a fatigue or symptom-limited bicycle exercise test in 16 patients referred to hospital because of dyspnoea. In total 181 paired measurements were made. Mean values (range) of PaO₂ and tcPO₂ were 11-2 kPa (5–16) and 9-5 (5–13-3), respectively. The correlation coefficient between PaO₂ and TcPO₂ was only 0–36 (P < 10^-5). By normalizing the values of tcPO₂ and PaO₂ to corresponding values at supine rest before exercise, the correlation coefficient increased to 0–80 (P < 10^-6). Using PaO₂ as golden standard, tcPO₂ described the trend in pO₂ during exercise reasonably well in all cases and this information is often sufficient for assessing the degree of pulmonary insufficiency. Thus, transcutaneous blood gas monitoring during exercise is useful for clinical evaluation of pulmonary disease, but a single arterial blood sample at rest before exercise is recommended for baseline correlation.,     

Pedal blood flow and transcutaneous PO2 in normal subjects and in patients suffering from severe arterial occlusive disease

Summary. Pedal transcutaneous partial pressure of oxygen (tcPo₂) has been measured by polarographic method, heating the skin at 44°C. In 50 normal subjects, mean tcPo₂ measured 54 · 5 ± 7 mmHg. Among 43 patients suffering from chronic ischaemia of lower limbs, mean tcPo₃ measured 40·8±8 mmHg in patients with from claudication and 16·1±15 mmHg in patients suffering from rest pain and/or gangrene. The variability of repeated tcPo₂ measurements, expressed as 1 SD of the mean, was 4·5 mmHg in normal subjects and 2·9 mmHg in patients. The relationships between pedal subcutaneous blood flow measured in xenon-133 clearance method and pedal tcPo₂ have been studied in nine normal subjects and in five patients suffering from severe chronic ischaemia of lower limbs (rest pain and/or gangrene). There was a positive correlation between blood flow and tcPo, in normal subjects (r=0·77, P< 0·001). In patients suffering from severe ischaemia, there was no correlation between these two parameters, but measured blood flow was sometimes very high in areas where tcPo₂ was low. It is likely that ¹³³Xe clearance method considerably overestimates local blood flow in these patients, because there is considerably less fat in subcutaneous tissue of chronic severely ischaemic areas. Thus, partition coefficient should be determined in each patient. However, tcPo₂ may constitute an index of nutritional circulation, while ¹³³Xe clearance actually measures total subcutaneous blood flow.     

Measurement of transcutaneous PCO2 in critically ill patients

Transcutaneous carbon dioxide tensions (tcPCO2) measured with a heated electrode were compared with arterial carbon tensions (PaCO2) in 28 patients. Seventy-eight observations were made. At a skin electrode temperature of 44 degrees C the tcPCO2 was significantly higher than PaCO2 but changes in PCO2 detected by both measurements were closely correlated. The correlation coefficient between tcPCO2 and PaCO2 was 0.92 (P less than 0.001). The 90% response time of the electrode in vitro was less than 1 min, and in vivo stabilization of the recording occurred in less than 15 min. It was found that the transcutaneous PCO2 electrode can be employed usefully in intensive care monitoring of adult patients especially when weaning them from artificial ventilation.     

Use of an iridium-oxide transcutaneous carbon dioxide electrode on adult surgical patients

A new iridium/iridium-oxide electrode heated to 42 degrees C was used to monitor transcutaneous carbon dioxide levels during surgery in 27 adult patients. The purpose of this study was to compare arterial and transcutaneous CO2 values. This metal electrode performed similarly to glass CO2 electrodes. In addition, its lower operating temperature may reduce the risk of skin injury and more quickly reflect changes in local tissue perfusion.     

Factors influencing transcutaneous oxygen and carbon dioxide measurements in adult intensive care patients

Transcutaneous PO2 (PtcO2) is suggested to reflect tissue oxygenation in intensive care patients, whereas transcutaneous PCO2 (PtcCO2) is advocated as a noninvasive method for assessing PaCO2. In 24 critically ill adult patients (mean Apache II score 14.2, SD 4.7) we investigated the impact of variables that are commonly thought to determine PtcO2 and PtcCO2 measurements. A linear correlation was found between PtcO2 and PaO2 (r = 0.6; p less than or equal to 0.0001) and between PtcO2 and mean arterial blood pressure (MAP; r = 0.42; p less than or equal to 0.003). Cardiac index (CI) correlated with tc-index (PtcO2/PaO2; r = 0.31; p less than or equal to 0.03). There was no relationship between PtcO2 and hemoglobin concentration (Hb) and the position of the oxygen dissociation curve (ODC). Stepwise multiple regression analysis demonstrated a significant influence of PaO2 and MAP on PtcO2. The contribution of CI, Hb and the ODC was not significant. Only 40% of the variability of a single PtcO2 measurement could be explained by PaO2 and MAP. A significant linear correlation was demonstrated between PtcCO2 and PaCO2 (r = 0.76; p less than or equal to 0.0001) but not between PtcCO2 and CI, MAP and arterial base excess (BEa). Stepwise multiple regression analysis revealed an influence of PaCO2 and of CI on PtcCO2; 66% of the variability of a single PtcCO2-value could be explained by PaCO2 and CI. Our data demonstrate that transcutaneous derived gas tensions result from complex interaction between hemodynamic, respiratory and local factors, which can hardly be defined in ICU-patients.     

Evaluation of corrosive poisoning in adult patients

ObjectiveTo evaluate the demographic characteristics, endoscopy results, emerging complications and the final status of caustic intake cases admitted to our emergency department.MethodThis study is a retrospective one concerning patients admitted to our emergency department due to caustic ingestion. Demographic characteristics of the patients, complaints while applying to the hospital, physical examination findings, the purpose of caustic intake, the characteristics of corrosive substance taken, times of endoscopy following admission to the emergency department, follow-up times in the emergency department, endoscopic staging and outcome. The data were analyzed through IBM SPSS Statistics Base 22.0 package program.ResultsSeventy four patients participated in the study. 83.8% of corrosive substance intake cases were accidental and 16.2% cases were suicidal intention. While 60.8% of the corrosive substances taken had alkaline property, 36.5% were acidic and 2.7% were found to be unknown substances. 50% of the corrosive substance intakes were sodium hypochlorite. It was seen that endoscopy was performed in 59 patients who accepted endoscopy within an average of 244.07 min after admission to the emergency department. While no damage could be seen in 55.9% of patients following endoscopy, the most common injury was Grade 1 (35.6%).ConclusionCorrosive substance intake is a rare but potentially devastating poisoning with high morbidity and mortality. Mucosal injury begins within minutes following corrosive intake. Therefore, early endoscopy is helpful in assessing the degree of injury and early discharge from hospital.     

Effects of anesthetic agents on the drift of a transcutaneous oxygen tension sensor

Both halothane and nitrous oxide can be reduced at the cathode of a polarographic oxygen electrode, causing the electrode current to drift upward and report falsely high oxygen tension. Because transcutaneous oxygen tension is measured by a heated oxygen electrode, there is a potential for significant upward drift of these values. To examine the clinical significance of this drift, the following study was performed. Transcutaneous oxygen tension sensors were calibrated at oxygen tensions of 0 mm Hg and 157 mm Hg (room air) just before clinical use during anesthesia. This calibration was rechecked immediately upon removal of the sensor from the patient at the end of the anesthesia. The predominant anesthetic agent used and the duration of monitoring were noted from the record. Data were collected from 208 patients representing a total of 463.6 hours of anesthesia. The patients were divided into five groups based on anesthetic administered: halothane, enflurane, isoflurane, nitrous oxide-narcotic, and local/regional. The mean zero point recalibration value was 0.4 mm Hg or less for all agents except halothane, for which it was 1.8 ± 3.2 mm Hg. This halothane drift was significantly greater than that for the other agents (P<0.01). Room air recalibration was not significantly different in any of the five groups, varying from 160 ± 4.9 mm Hg for halothane to 157 ± 4.9 mm Hg for enflurane. All these drift values are within the manufacturer’s specifications. We conclude that the drift of the transcutaneous oxygen tension sensor due to anesthetic agents is not clinically significant. However, caution should be exercised when halothane is used during an extremely long period of anesthesia.     

84例成人Evans综合征临床资料分析

目的 探讨成人Evans综合征的初始临床特征,各种治疗方法 的疗效及病程.方法 对84例成人Evans综合征患者(男20例,女64例)应用激素、丙种免疫球蛋白、免疫抑制剂多药联合治疗,中位随访17.5(0.03～140)个月,观察患者起病特征及临床疗效.结果 所有患者均接受激素加或不加静脉丙种免疫球蛋白初始治疗.47例患者单用激素治疗,其中38例达完全缓解(CR)和部分缓解(PR).中位随访12个月,92.1%的患者复发.28例对激素耐药或出现严重出血的患者随后给予免疫抑制剂治疗,89.3%的患者获得CR或PR.中位随访8个月,84%患者复发.结论 Evans 综合征难治且易复发,联合治疗可能是治疗Evans综合征的有效手段.     

Cardiac index measurements by transcutaneous Doppler ultrasound and transthoracic echocardiography in adult and pediatric emergency patients

Introduction  

Non-invasive hemodynamic monitoring may facilitate resuscitation in critically ill patients. Validation studies examining a transcutaneous Doppler ultrasound technology, USCOM-1A, using pulmonary artery catheter as the reference standard showed varying results. In this study, we compared non-invasive cardiac index (CI) measurements by USCOM-1A with transthoracic echocardiography (TTE).     

Improvement in glycemic excursions with a transcutaneous, real-time continuous glucose sensor: a randomized controlled trial

OBJECTIVE: Hypoglycemia and wide glucose excursions continue to be major obstacles to achieving target HbA(1c) values and the associated reductions in long-term complications (and economic costs) in people with insulin-treated diabetes. In this study we evaluated the accuracy, safety, and clinical effectiveness of a continuous glucose-sensing device. RESEARCH DESIGN AND METHODS: A total of 91 insulin-requiring patients with type 1 (n = 75) and type 2 (n = 16) diabetes were enrolled in this multicenter randomized study. Subjects wore a transcutaneous, 3-day, continuous glucose-sensing system for three consecutive 72-h periods. Subjects were randomly assigned (1:1 ratio) to either a control group (continuous glucose data not provided) or a display group (continuous glucose data not provided during period 1 but displayed during periods 2 and 3). During periods 2 and 3, patients in the display group had real-time access to sensor glucose values, could review glucose trends over the preceding 1, 3, and 9 h, and were provided with high (> or = 200 mg/dl) and low (< or = 80 mg/dl) alerts and a low (< or = 55 mg/dl) alarm. Sensors were inserted by patients, and both groups used (or wore) the system during daily activities. Device accuracy was assessed by comparing continuous glucose values to paired self-monitoring of blood glucose (SMBG) meter readings. Clinical effectiveness was evaluated by analyzing between-group (control vs. display, periods 2 and 3) and within-group (display, period 1 vs. period 3) differences in time spent in high, low, and target (81-140 mg/dl) glucose zones. RESULTS: When prospective, real-time sensor values were compared with SMBG values, 95.4% of 6,767 paired glucose values fell within Clarke error grid A and B zones. Pearson's correlation coefficient was 0.88, and mean and median absolute relative differences were 21.2 and 15.9%, respectively. No systematic bias was detected at any of the prespecified glucose levels (50, 80, 100, 150, and 200 mg/dl). When compared with control subjects, the display group spent 21% less time as hypoglycemic (<55 mg/dl), 23% less time as hyperglycemic (> or = 240 mg/dl), and 26% more time in the target (81-140 mg/dl) glucose range (P < 0.001 for each comparison). Nocturnal (10:00 p.m. to 6:00 a.m.) hypoglycemia, as assessed at two thresholds, was also reduced by 38% (<55 mg/dl; P < 0.001) and 33% (55-80 mg/dl; P < 0.001) in the display group compared with control subjects. CONCLUSIONS: We conclude that real-time continuous glucose monitoring for periods up to 72 h is accurate and safe in insulin-requiring subjects with type 1 and type 2 diabetes. This study demonstrates that availability of real-time, continuously measured glucose levels can significantly improve glycemic excursions by reducing exposure to hyperglycemia without increasing the risk of hypoglycemia, which may reduce long-term diabetes complications and their associated economic costs.     

Prolonged spiking in the Emfit sensor in patients with sleep-disordered breathing is characterized by increase in transcutaneous carbon dioxide

A phenomenon of prolonged spiking in movement sensors, such as static-charge-sensitive bed or Emfit (electromechanical film) sensors, has been connected to an increase in carbon dioxide tension in wakefulness. Spiking is also a common finding in sleep studies. This made us hypothesize that carbon dioxide changes might also happen in sleep during prolonged spiking episodes in Emfit sheet. We examined four different kinds of breathing pattern episodes: normal breathing, episodes of repetitive apnea, episodes of repetitive hypopnea and episodes with prolonged spiking lasting at least 3 min. One hundred and fifteen episodes from 19 polysomnograms were finally admitted to the study according to the protocol. The changes in the transcutaneous carbon dioxide tension (TcCO(2)) were defined for different breathing patterns. During prolonged spiking episodes the TcCO(2) increased significantly and differed statistically from the TcCO(2) changes of normal breathing and periodic breathing patterns (episodes of apnea and hypopnea). The rise in TcCO(2) during prolonged spiking episodes might suggest that prolonged spiking is representing another type of breathing disturbance during sleep differing from periodic breathing patterns. The Emfit sensor as a small, flexible and non-invasive sensor might provide useful additional information about breathing during sleep.     

Fluoroless catheter ablation of accessory pathways in adult and pediatric patients: a single centre experience

The International Journal of Cardiovascular Imaging - Catheter radio-frequency ablation (RFA) and cryo-ablation (CRA) procedures are an effective and safe treatment options for adult and pediatric...     

Evaluation of a new pulse oximeter sensor.

BACKGROUND: A new forehead noninvasive oxygen saturation sensor may improve signal quality in patients with low cardiac index. OBJECTIVES: To examine agreement between oxygen saturation values obtained by using digit-based and forehead pulse oximeters with arterial oxygen saturation in patients with low cardiac index. METHODS: A method-comparison study was used to examine the agreement between 2 different pulse oximeters and arterial oxygen saturation in patients with low cardiac index. Readings were obtained from a finger and a forehead sensor and by analysis of a blood sample. Bias, precision, and root mean square differences were calculated for the digit and forehead sensors. Differences in bias and precision between the 2 noninvasive devices were evaluated with a t test (level of significance P<.05). RESULTS: Nineteen patients with low cardiac index (calculated as cardiac output in liters per minute divided by body surface area in square meters; mean 1.98, SD 0.34) were studied for a total of 54 sampling periods. Mean (SD) oxygen saturations were 97% (2.4) for blood samples, 96% (3.2) for the finger sensor, and 97% (2.8) for the forehead sensor. By Bland Altman analysis, bias +/- precision was -1.16 +/- 1.62% for the digit sensor and -0.36 +/- 1.74% for the forehead sensor; root mean square differences were 1.93% and 1.70%, respectively. Bias and precision differed significantly between the 2 devices; the forehead sensor differed less from the blood sample. CONCLUSIONS: In patients with low cardiac index, the forehead sensor was better than the digit sensor for pulse oximetry.