Changes of transcutaneous oxygen pressure in compressed areas of surgical patients: A prospective study of influencing factors.

OBJECTIVE: To compare the transcutaneous oxygen pressure (tcpO2) measurement values and changes in compressed areas of surgical patients before and after surgery and to explore the related factors influencing the tcpO2 changes before and after surgery. METHODS: Researchers selected 100 patients who underwent elective surgery in a tertiary comprehensive hospital from November 2021 to September 2022. A self-designed general information questionnaire was used to collect patient general information and disease-related data, including gender, age, smoking and drinking history, hypertension, diabetes, local skin temperature and humidity, related biochemical indicators, and activities of daily living score. Researchers used a transcutaneous oxygen pressure meter to measure and record the tcpO2 of the compressed areas (sacrococcygeal area, scapula area, and heel area) before and after surgery. RESULTS: Among the 100 patients, 37.00 % (37/100) developed type I/II pressure ulcers after surgery, and 30 patients (81.08 %) showed regression within 2 h after surgery. There was no statistically significant difference in the preoperative tcpO2 measurement values of the scapula and heel areas between the group with and without pressure ulcers, but the preoperative tcpO2 measurement value of the sacrococcygeal area in the group without pressure ulcers was higher than that in the group with pressure ulcers (P < 0.01). The factors affecting the preoperative tcpO2 measurement value of the sacrococcygeal area were smoking and surgical type. After surgery, the tcpO2 measurement values of the three areas in the group with pressure ulcers were significantly lower than those in the group without pressure ulcers (P < 0.01). Comparing the tcpO2 values of different areas, it was found that the tcpO2 value was lowest in the sacrococcygeal area, followed by the heel area, and the tcpO2 value in the scapula area was highest both before and after surgery (P < 0.01). The main factors affecting the postoperative tcpO2 measurement value were diabetes, Glassgow score, surgical time, and intraoperative red blood cell transfusion. CONCLUSION: The measurement of tcpO2 is related to the incidence of surgically acquired pressure ulcers, and this technology may become an important tool for quantitative assessment of the risk of pressure ulcers.

Epidemiological investigation of vascular etiological examinations in the diagnosis and treatment of lower-extremity ulcers in China.

The vascular causes of lower-extremity ulcers cannot be neglected because they can directly affect treatment methods. No detailed epidemiological statistics have described vascular etiological diagnosis in China. This study aimed to explore the prevalence of clinical vascular etiological examination of lower-extremity ulcers and improve the diagnosis and treatment effectiveness of lower-extremity ulcers. Data were collected from the WoundCareLog database, which includes 2413 cases of lower-extremity ulcers from 478 hospitals nationwide. Data analysis revealed that 1698 (70.4%) lower-extremity blood flow examinations (including physical examination [PE] and assistant examinations [AE]) were performed, of which 61.7% were PE, 10.4% were AE only, and 27.9% were the combined PE and AE[PAE]. The proportion of nonexaminations was higher in the nondiabetic group than in the diabetic group (χ2 = 34.5; P < .01). The positive rates of vascular etiological examination in the diabetic and nondiabetic groups were 69.7% and 70.7%, respectively. Among the four economic regions of China, there were statistically significant differences in the use of the different examination methods. The examination of vascular diseases in lower-extremity ulcers in China has not been fully popularized and requires improvement; there was no statistically significant difference between examination rates by doctors and nurses, which is mainly based on PE. However, PE has certain rates of misdiagnosis and missed diagnosis. The false-positive and false-negative rates were 25.7% and 57.6%, respectively. The use of an AE can compensate for this deficiency by making diagnosis more precise, while the quantitative diagnostic criteria allow disease diagnosis to transcend geographical and operator differences and maximize uniformity. The vascular B-ultrasound examination is more suitable for the medical environment in China because of its mature technology, high hospital penetration rate, and low cost.

Most impactful predictors for hyperoxaemia in exacerbation of chronic obstructive pulmonary disease managed by Emergency Medical Services and Emergency Department.

INTRODUCTION: Hyperoxemia in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) leads to adverse outcomes. It remains prevalent in the pre-hospital Emergency Medical Services (EMS) and Emergency Department (ED). OBJECTIVE: To determine the key predictors for hyperoxemia in AECOPD in EMS and ED. METHODS: This was a prospective observational study of AECOPD patients in EMS and two EDs. Hyperoxemia was defined as PaO2 > 65 mm Hg (corresponds to SpO2 > 92%). We determined apriori candidate factors in Patient, Organization and Staff domains. Primary outcomes were the key predictors for hyperoxemia. Secondary outcomes were in-hospital mortality and mechanical ventilation rates in hyperoxemic versus non-hyperoxemic groups. We generated a logistic regression model for each domain. We reported the adjusted odds ratios (AORs), 95% CIs and p values. We selected the output factors using AOR ≥2.0 and ≥2.5 for modifiable and non-modifiable factors, respectively. These selected factors were fed into a final model with eventual factors selected based on: threshold AORs as stated above and/or 95% CIs including these AORs. RESULTS: Three hundred and twenty-six patients were analysed; 60.7% had hyperoxemia. We found three eventual modifiable factors; first, ED SpO2 > 95% [AOR 2.62 (95% CIs: 1.61-4.33); P < 0.001], EMS non-rebreathing mask [AOR 2.01 (95% CIs: 1.06-3.97); P = 0.04]; and ED nasal cannula [AOR 1.69 (95% CIs: 1.05-2.72); P = 0.03]. Secondary outcomes did not differ between groups. CONCLUSION: We identified three key modifiable predictors. We intend to conduct an interventional study using them to reduce hyperoxemia rate in AECOPD.

Accuracy of Transcutaneous Carbon Dioxide Levels in Comparison to Arterial Carbon Dioxide Levels in Critically Ill Children.

BACKGROUND: Widespread use of transcutaneous PCO2 (PtcCO2 ) monitoring is currently limited by concerns many practitioners have regarding accuracy. We compared the accuracy of PtcCO2 with that of PaCO2 measurements in critically ill children, and we investigated whether clinical conditions associated with low cardiac output or increased subcutaneous tissue affect this accuracy. METHODS: We performed a single-center prospective study of critically ill children placed on transcutaneous monitoring. RESULTS: There were 184 children enrolled with paired PaCO2 and PtcCO2 values. Subjects had a median age of 31.8 mo (interquartile range 3.5-123.3 mo). Most children were mechanically ventilated (n = 161, 87.5%), and many had cardiac disease (n = 76, 41.3%). The median PaCO2 was 44 mm Hg (interquartile range 39-51 mm Hg). The mean bias between PaCO2 and PtcCO2 was 0.6 mm Hg with 95% limits of agreement from -13.6 to 14.7 mm Hg. The PtcCO2 and PaCO2 were within ±5 mm Hg in 126 (68.5%) measurements. In multivariable modeling, cyanotic heart disease (odds ratio 3.5, 95% CI 1.2-10, P = .02) and monitor number 2 (odds ratio 3.8 95% CI 1.3-10.5, P = .01) remained associated with PtcCO2 ≥ 5 mm Hg higher than PaCO2 . Serum lactate, fluid balance, renal failure, obesity, vasoactive-inotrope score, and acyanotic heart disease were not associated with high or low PtcCO2 values. In 130 children with a second paired PtcCO2 and PaCO2 measurement, predicting the second measured PaCO2 by subtracting the initial observed difference between the PtcCO2 and PaCO2 from the subsequent measured PtcCO2 decreased the mean bias between observed and predicted PaCO2 to 0.2 mm Hg and the 95% limits of agreement to -9.4 to 9.7 mm Hg. CONCLUSIONS: PtcCO2 provides an acceptable estimate of PaCO2 in many critically ill children, including those with clinical conditions that may be associated with low cardiac output or increased subcutaneous tissue, although it does not perform as well in children with cyanotic heart disease. PtcCO2 may be a useful adjunct monitoring method, but it cannot reliably replace PaCO2 measurement.

Accuracy of Transcutaneous CO2 Values Compared With Arterial and Capillary Blood Gases.

BACKGROUND: Transcutaneous monitors are utilized to monitor a patient's respiratory status. Some patients have similar values when comparing transcutaneous carbon dioxide (PtcCO2 ) values with blood gas analysis, whereas others show extreme variability. A retrospective review of data was performed to determine how accurately PtcCO2 correlated with CO2 values obtained by arterial blood gas (ABG) or capillary blood gas. METHODS: To determine whether PtcCO2 values correlated with ABG or capillary blood gas values, subjects' records were retrospectively reviewed. Data collected included the PtcCO2 value at the time of blood gas procurement and the ABG or capillary blood gas PCO2 value. Agreement of pairs of methods (ABG vs PtcCO2 and capillary blood gas vs PtcCO2 ) was assessed with the Bland-Altman approach with limits of agreement estimated with a mixed model to account for serial measurements per subject. RESULTS: A total of 912 pairs of ABG/PtcCO2 values on 54 subjects and 307 pairs of capillary blood gas/PtcCO2 values on 34 subjects were analyzed. The PCO2 range for ABG was 24-106 mm Hg, and PtcCO2 values were 27-133 mm Hg. The PCO2 range for capillary blood gas was 29-108 mm Hg, and PtcCO2 values were 30-103 mm Hg. For ABG/PtcCO2 comparisons, the Pearson correlation coefficient was 0.82, 95% CI was 0.80-0.84, and P was <.001. For capillary blood gas/PtcCO2 comparisons, the Pearson correlation coefficient was 0.77, 95% CI was 0.72-0.81, and P was <.001. For ABG/PtcCO2 , the estimated difference ± SD was -6.79 ± 7.62 mm Hg, and limits of agreement were -22.03 to 8.45. For capillary blood gas/PtcCO2 , the estimated difference ± SD was -1.61 ± 7.64 mm Hg, and limits of agreement were -16.88 to 13.66. The repeatability coefficient was about 30 mm Hg. CONCLUSIONS: Based on these data, capillary blood gas comparisons showed less variation and a slightly lower correlation with PtcCO2 than did ABG comparisons. After accounting for serial measurements per patient, due to the wide limits of agreement and poor repeatability, the utility of relying on PtcCO2 readings for this purpose is questionable.

Exogenous surfactant and alveolar recruitment in the treatment of the acute respiratory distress syndrome.

OBJECTIVE: To investigate the effect of alveolar recruitment combined with surfactant administration on children with acute respiratory distress syndrome (ARDS). MATERIAL AND METHODS: A prospective, randomized, controlled and sequential study was carried out. Group A (16 children) was treated with both the alveolar recruitment manoeuvres (ARM) and the administration of the surfactant every 8 h for 3 days; group B (15) received the usual treatment only. The alveolar recruitment was carried out by increasing positive end-expiratory pressure 2 by 2 cm H2 O to improve the transcutaneous oxygen saturation values up to 88% and 90%. Demographic data, gasometric and ventilator parameters, chest radiography and 28-day mortality were evaluated. RESULTS: There were no significant differences in baseline characteristics between groups. An hour after treatment, significant differences (P < 0.001) were observed in transcutaneous oxygen saturation (SaO2 ; Group A: 94.1%, Group B: 89.9%), PaO2 /FiO2 (212.7 and 126.4) and oxygenation index (OI; 11.4 and 18.5). After 8 h, the differences in SaO2 (Group A: 94.6%, Group B: 90.3%), PaO2 /FiO2 (225.8 and 126.9) and OI (10.8 and 18.4) were also significant (P < 0.001). From the fifth dose of the surfactant, the static compliance (P = 0.0034) and radiological images (P = 0.002) were more greatly improved in group A than in group B. Survival was significantly higher in group A (81.3%) than in group B (26.7%) (P = 0.006). CONCLUSIONS: The combined treatment of surfactant administration and ARM resulted in a better oxygenation and survival in children with ARDS than when only recruitment was used.

Transcutaneous Carbon Dioxide Monitoring in Subjects With Acute Respiratory Failure and Severe Hypercapnia.

BACKGROUND: Transcutaneous carbon dioxide (P(tcCO2)) monitoring is being used increasingly to assess acute respiratory failure. However, there are conflicting findings concerning its reliability when evaluating patients with high levels of P(aCO2). Our study evaluates the accuracy of this method in subjects with respiratory failure according to the severity of hypercapnia. METHODS: We included subjects with respiratory failure, admitted to a respiratory intermediate care unit, who required arterial blood gas analysis. Simultaneously, P(tcCO2) was measured using a digital monitor. Relations between P(aCO2) and P(tcCO2) were assessed by the Pearson correlation coefficient. Bland-Altman analysis was used to test data dispersion, and an analysis of variance test was used to compare the differences between P(aCO2) and the corresponding P(tcCO2) at different levels (level 1, <50 mm Hg; level 2, 50-60 mm Hg; level 3, >60 mm Hg). RESULTS: Eighty-one subjects were analyzed. The main diagnosis was COPD exacerbation (45%). P(tcCO2) correlated well with P(aCO2) (r2 = 0.93, P < .001). Bland-Altman analysis showed a mean P(aCO2) - P(tcCO2) difference of 4.9 ± 4.4 with 95% limits of agreement ranging from -3.6 to 13.4. The difference between variables increased in line with P(aCO2) severity: level 1, 1.7 ± 3.2 mm Hg; level 2, 3.7 ± 2.8; level 3, 6.8 ± 4.7 (analysis of variance, P < .001). CONCLUSIONS: Our study showed an acceptable agreement of P(tcCO2) monitoring with arterial blood gas analysis. However, we should consider that P(tcCO2) underestimates P(aCO2) levels, and its accuracy depends on the level of hypercapnia, so this method would not be suitable for acute patients with severe hypercapnia.

The Monitoring and Management of Severe Traumatic Brain Injury in the United Kingdom: Is there a Consensus?: A National Survey.

BACKGROUND: To survey the current practice of monitoring and management of severe traumatic brain injury (TBI) patients in the critical care units across the United Kingdom. METHODS: A structured telephone interview was conducted with senior medical or nursing staff of all the adult neurocritical care units. Thirty-one neurocritical care units that managed adult patients with severe TBI were identified from the Risk Adjustment in Neurocritical Care (RAIN) study and the Society of British Neurological Surgeons. RESULTS: Intracranial pressure (ICP) monitoring was used in all the 31 institutions. Cerebral perfusion pressure was used in 30 of the 31 units and a Cerebral perfusion pressure target of 60 to 70 mm Hg was the most widely used target (25 of 31 units). Transcranial Doppler was used in 12 units (39%); brain tissue oxygen (PbtO(2)) was used in 8 (26%); cerebral microdialysis was used in 4 (13%); jugular bulb oximetry in 1 unit; and near-infrared spectrometry was not used in any unit. Continuous capnometry was used in 28 (91%) units for mechanically ventilated patients. Mannitol was the most commonly used agent for osmotherapy to treat intracranial hypertension. CONCLUSIONS: We identified that there was no clear consensus and considerable variation in practice in the management of TBI patients in UK neurocritical care units. A protocol-based management has been shown to improve outcome in sepsis patients. Given the magnitude of the problem, we conclude that there is an urgent need for international consensus guidelines for management of TBI patients in critical care units.

The use of transcutaneous CO2 monitoring in cardiac arrest patients: a feasibility study.

BACKGROUND: Prediction of the return of spontaneous circulation (ROSC) in cardiac arrest patients is a parameter for deciding when to stop cardiopulmonary resuscitation (CPR) or to start extracorporeal CPR. We investigated the change in transcutaneous PCO2 (PtcCO2) in cardiac arrest patients. METHODS: This study was carried out as a retrospective chart review. Patients with out-of-hospital cardiac arrest or in-hospital cardiac arrest within the emergency department were included. PtcCO2 monitoring with a V-Sign™ combined monitor (SenTec Inc., Therwil, Switzerland) was applied to patients at the start of CPR. We divided the included patients into the ROSC group and the no ROSC group. The ROSC group was subdivided into those achieving ROSC <15 min CPR and >15 min CPR. The change in the PtcCO2 value was analyzed at 0 min, 5 min, 10 min, and 15 min from PtcCO2 stabilization and was compared among the groups. RESULTS: A total of 42 patients were enrolled. Twenty-eight patients achieved ROSC; 13 patients achieved ROSC <15 min CPR and 15 patients achieved ROSC >15 min CPR. Fourteen patients expired without ROSC. The absolute values of PtcCO2 was lower in the ROSC group than in the no ROCS group. The PtcCO2 change over time had a tendency to decrease or to remain constant in the ROSC groups. In contrast, all patients in the no ROSC group experienced an increase in the PtcCO2 change during CPR except one case. CONCLUSIONS: PtcCO2 monitoring provides non-invasive, continuous, and useful monitoring in cardiac arrest patients.

Provision of home mechanical ventilation and sleep services for England survey.

The Department of Health is promoting the generation of specialist networks to manage long term ventilatory weaning and domiciliary non-invasive ventilation patients. Currently the availability of these services in England is not known. We performed a short survey to establish the prevalence of sleep and ventilation diagnostic and treatment services. The survey focussed on diagnostic services and Home Mechanical Ventilation (HMV) provision, and was divided into (a) availability of diagnostics, (b) funding, and (c) patient groups. This survey has confirmed that the majority of Home Mechanical Ventilation set-ups are currently for Obesity Related Respiratory Failure and Chronic Obstructive Pulmonary Disease. We have found that there is variable provision of diagnostic services, with the majority of units offering overnight oximetry (95%) but only 55% of responders providing a home mechanical ventilation service. Even more interestingly, less than two thirds of units charged their primary care trust for this service. These data may assist in the development of regional networks and specialist home mechanical ventilation centres.

The use of transcutaneous oximetry to predict healing complications of lower limb amputations: a systematic review and meta-analysis.

OBJECTIVE: To determine the validity of transcutaneous oximetry (TcPO(2)) as a predictor of lower limb amputation healing complications. DESIGN: A systematic review and meta-analysis. METHODS: We searched five major medical databases, relevant review articles and reference lists and included all studies that evaluated TcPO(2) for its ability to predict lower limb amputation healing failure. We selected eligible articles and conducted data abstraction independently and in duplicate. RESULTS: Thirty-one studies, enrolling 1824 patients with 1960 amputations, met our inclusion criteria. Only one study reported undertaking a multivariable analysis, which demonstrated that a TcPO(2) level below 20 mmHg was an independent predictor of re-amputation occurrence (adjusted odds ratio (OR) 3.08, 95% confidence interval (CI) 1.19-7.98). Fourteen prospective cohort studies reported data that allowed for the calculation of an unadjusted relative risk of lower limb amputation healing complications leading to amputation revision associated with a TcPO(2) level below cut-offs of 10 mmHg (1.80; 95% CI 1.19-2.72), 20 mmHg (1.75; 95% CI 1.27-2.40) 30 mmHg (1.41; 95% CI 1.22-1.62) and 40 mmHg (1.24; 95% CI 1.13-1.39). CONCLUSIONS: This review suggests that TcPO(2) predicts healing complications of lower limb amputations. A value of less than 40 mmHg results in a 24% increased risk of healing complication compared to over 40 mmHg and the risk further increases as the TcPO(2) decreases. There is, however, insufficient evidence to judge whether this tool adds important information beyond clinical data or to suggest an optimal threshold value. There is a need for a large, sufficiently powered study that adjusts for appropriate clinical variables.

[Quality of initial prescription of home oxygen therapy in a healthcare area of the Murcia Region (Spain)]. / Calidad de la prescripción inicial de la oxigenoterapia domiciliaria en un área sanitaria de la Región de Murcia.

OBJECTIVE: To analyse the quality of the prescription of home oxygen therapy (OT) in a health area of Murcia. METHODS: A prospective study of 125 patients in a respiratory therapy clinic, evaluated with a questionnaire and blood-gas analysis while breathing ambient air. Related respiratory therapy was also assessedin COPD and asthma patients. RESULTS: We studied 125 cases in the 3 months following the prescription of home oxygen therapy in 72 men (58%) and 53 women (42%) with a mean age of 77.2 ± 11.6. The most common type of home OT prescribed was for palliative cases in 45 patients (36%), followed by COPD in 42 (33.6%). In 88 (92%) of the 96 medical reports that we evaluated, insufficient data as to how to administer oxygen were available. Twenty-five percent of home OT prescriptions were given without blood-gas analyses, and in the 65 cases with a blood-gas analysis only 11 (17%) met oxygen value criteria for home OT as per regulations. Oxygen desaturation was not present in 31% of the palliative care home OT cases. The analysis of blood-gases during the clinic visit in non-palliative care cases demonstrated that 61% did not meet the blood-gas criteria to continue on home OT. Eighty percent of COPD and asthma patients on home OT did not receive the correct respiratory therapy. CONCLUSIONS: Quality problems in the prescription of home OT exist in our area. Palliative care is the principal reason for home OT prescriptions. In COPD and asthma patients who receive home OT, related respiratory therapy is not ideal.

Changes in near infrared spectroscopy during deep hypothermic circulatory arrest.

Monitoring cerebral oxygenation with near infrared spectroscopy may identify periods of cerebral desaturation and thereby the patients at risk for perioperative neurocognitive issues. Data regarding the performance of near infrared spectroscopy monitoring during deep hypothermic circulatory arrest are limited. The current study presents data regarding use of a commercially available near infrared spectroscopy monitor during deep hypothermic circulatory arrest in paediatric patients undergoing surgery for congenital heart disease. The cohort included 8 patients, 2 weeks to 6 months of age, who required deep hypothermic circulatory arrest for repair of congenital heart disease. The baseline cerebral oxygenation was 63 +/- 11% and increased to 88 +/- 7% after 15 min of cooling to a nasopharyngeal temperature of 17-18 degrees C on cardiopulmonary bypass. In 5 of 8 patients, the cerebral oxygenation value had achieved its peak value (either >or=90% or no change during the last 2-3 min of cooling on cardiopulmonary bypass). In the remaining 3 patients, additional time on cardiopulmonary bypass was required to achieve a maximum cerebral oxygenation value. The duration of deep hypothermic circulatory arrest varied from 36 to 61 min (43.4 +/- 8 min). After the onset of deep hypothermic circulatory arrest, there was an incremental decrease in cerebral oxygenation to a low value of 53 +/- 11%. The greatest decrease occurred during the initial 5 min of deep hypothermic circulatory arrest (9 +/- 3%). Over the entire period of deep hypothermic circulatory arrest, there was an average decrease in the cerebral oxygenation value of 0.9% per min (range of 0.5 to 1.6% decline per minute). During cardiopulmonary bypass, cooling and deep hypothermic circulatory arrest, near infrared spectroscopy monitoring followed the clinically expected parameters. Such monitoring may be useful to identify patients who have not achieved the highest possible cerebral oxygenation value despite 15 min of cooling on cardiopulmonary bypass. Future studies are needed to define the cerebral oxygenation value at which neurological damage occurs and if interventions to correct the decreased cerebral oxygenation will improve perioperative outcomes.

Changes in respiration mediate changes in fear of bodily sensations in panic disorder.

The purpose of the study was to examine whether changes in pCO(2) mediate changes in fear of bodily sensation (as indexed by anxiety sensitivity) in a bio-behavioral treatment for panic disorder that targets changes in end-tidal pCO(2). Thirty-five panic patients underwent 4 weeks of capnometry-assisted breathing training targeting respiratory dysregulation. Longitudinal mediation analyses of the changes in fear of bodily symptoms over time demonstrated that pCO(2), but not respiration rate, was a partial mediator of the changes in anxiety sensitivity. Results were supported by cross lag panel analyses, which indicated that earlier pCO(2) levels predicted later levels of anxiety sensitivity, but not vice versa. PCO(2) changes also led to changes in respiration rate, questioning the importance of respiration rate in breathing training. The results provide little support for changes in fear of bodily sensations leading to changes in respiration, but rather suggest that breathing training targeting pCO(2) reduced fear of bodily sensations in panic disorder.

Clinical validation of a digital transcutaneous PCO2/SpO2 ear sensor in adult patients after cardiac surgery.

OBJECTIVE: The aim of this study was to validate the V-Sign digital sensor (SenTec AG, Therweil, Switzerland) for combined noninvasive assessment of pulse oxymetric oxygen saturation (SpO(2)) and transcutaneous carbon dioxide tension (PtcCO(2)) in adults after cardiac surgery. METHODS: In twenty one patients, aged 51-86 years, simultaneous measurements of blood gases with the V-Sign Sensor and with two Nellcor Durasensors (model DS-100A), one at the opposite earlobe and one with a finger clip, were compared first during hyper-, normo- and hypocapnia and at different pulse rates using a pacemaker, and then at 2-h intervals up to 8 h. Agreement was assessed by Bland-Altman analysis. RESULTS: PtcCO(2) data of three patients were excluded because of calibration failure of the device. Median (range) PtcCO(2) for the remaining patients was 5.49 (3.3-7.6) kPa and arterial carbon dioxide tension (PaCO(2)) was 5.43 (3.61-7.41) kPa. Corresponding mean bias was +0.05 kPa and limits of agreement (LOA) were -1.2/+1.3 kPa. During normo- and hypoventilation, mean bias was good at +0.02 and +0.04 kPa respectively, but limits of agreement were poor at -0.67/+0.69 and -0.81/+0.88 kPa. In 10 patients, an initial overshoot of PtcCO(2 )was observed. Mean bias of SpO(2) and pulse rate was close to zero (-1.5% and +0.001 bpm respectively), but limits of agreement were unacceptably high (-21.4/+18.4% and -22.3/+22.3 bpm). CONCLUSIONS: In the present state of development the SenTeC Digital monitor V-Sign device has serious limitations. Additional efforts are necessary to eliminate calibration failures and the initial overshoot of PtcCO(2) as well as to improve detection of SpO(2) and pulse rate.

Clinical evaluation of time-resolved spectroscopy by measuring cerebral hemodynamics during cardiopulmonary bypass surgery.

We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm. We also simultaneously monitored jugular venous oxygen saturation (SjvO(2)) and arterial blood hematocrit (Hct) using conventional methods. The validity and usefulness of the TRS system were assessed by comparing parameters obtained with the TRS and conventional methods. Although the changes in SO(2) were lower than those in SjvO(2), SO(2) obtained by TRS paralleled the fluctuations in SjvO(2), and a good correlation between these values was observed. The only exceptions occurred during the perfusion period. Moreover, there was a good correlation between tHb and Hct values (r(2)=0.63). We concluded that time-resolved spectroscopy reflected the conditions of cerebral hemodynamics of patients during surgical operations.

Emergency department procedural sedation and analgesia: A Canadian Community Effectiveness and Safety Study (ACCESS).

OBJECTIVES: To determine the effectiveness and safety of procedural sedation and analgesia (PSA) in a Canadian community emergency department (ED) staffed primarily by family physicians and to assess the role of capnometry monitoring in PSA. METHODS: One hundred and sixty (160) consecutive procedural sedation cases were reviewed from the ED of a rural hospital in Huntsville, Ont. The ED is mainly staffed by family physicians who have received in-house training in PSA. Safety and effectiveness measures were extrapolated from a standardized PSA form by a blinded research assistant. RESULTS: The mean age of the patient population was 33.6 years (standard deviation = 23.6). Fifty-four percent of the patients were male, and 33% of the cases were pediatric. PSA medications included propofol (84%), fentanyl (51%) and midazolam (15%), and the procedural success rate was 95.6%. The adverse event (AE) rate was 18% and included apnea (10%), inadequate sedation (3%), bradycardia (2%), desaturation (1%), hypotension (1%) and bag-valve-mask use (1%). In those aged > or = 65 years there was a greater incidence of apnea. There were no episodes of emesis and there were no intubations. A modified jaw thrust manoeuvre was used in 23% of the cases. I the 64% of cases where capnometry was used, there was no association between its use and any AE measures. CONCLUSION: Procedural sedation was safe and effective in our environment. Capnometry recording did not appear to alter outcomes, although the data are incomplete.

Effect of aging on the relationship between asthma severity and bronchial hyperresponsiveness in children with asthma.

An association between asthma and bronchial hyperresponsiveness (BHR) has been demonstrated. It is possible that the relationship between asthma severity and BHR in children with asthma is different in infants and in adolescents. The aim of this study is therefore to evaluate the effect of aging on the relationship between the severity of asthma and BHR in children with asthma. We measured BHR in 386 subjects ranging from 2 to 20 years of age. The subjects consisted of 323 children with asthma (boys:girls = 193:130, mean age 9.7 years) and 63 age-matched controls (boys:girls = 25:38, mean age 8.2 years). BHR was measured using the methacholine inhalation challenge by measuring the transcutaneous oxygen pressure (tcPO2) in children less than 6 years of age (Dmin-PO2) and by measuring the respiratory resistance (Rrs) in children 6 years of age and older (Dmin-Rrs). Throughout the whole age range, both the Dmin-PO2 and Dmin-Rrs in each asthma severity group were higher than those in the controls. In the asthmatics aged 2-5 years, the Dmin-PO2 levels in the mild asthma group were higher than those in the moderate and severe asthma groups (p < 0.001, p < 0.001, respectively), and the Dmin-PO2 levels in the moderate asthma group were also higher than those in the severe asthma group. This tendency was also found in the age ranges of 6-9 years and 10-13 years. In the asthmatics aged 14-20 years, the Dmin-Rrs levels were not significantly different among the three groups. Taken together, these data show that aging has an effect on the relationship between the severity of asthma and BHR during childhood and that BHR may not be the sole determinant for the severity of asthma in adolescence.

Oxygen saturation regularity analysis in the diagnosis of obstructive sleep apnea.

OBJECTIVE: The present study assessed the validity of approximate entropy (ApEn) analysis of arterial oxygen saturation (SaO(2)) data obtained from pulse oximetric recordings as a diagnostic test for obstructive sleep apnea (OSA) in patients clinically suspected of suffering this disease. METHODOLOGY: A sample of 187 referred outpatients, clinically suspected of having OSA, was studied using nocturnal pulse oximetric recording performed simultaneously with complete polysomnography. ApEn analysis was applied to SaO(2) data. RESULTS: Patients with OSA presented significantly higher approximate entropy levels than those without OSA (1.08+/-0.30 versus 0.47+/-0.26). Apnea-hypopnea index was correlated significantly with ApEn (r=0.607; p<0.001). Using receiver operating characteristic curve analysis, we obtained a diagnostic sensitivity of 88.3% and specificity of 82.9%, positive predictive value of 88.3% and a negative predictive value of 82.9%, at a threshold of 0.679. As a diagnostic test, this method presents high sensitivity and specificity compared to traditional methods in the diagnosis of OSA. CONCLUSION: We conclude that ApEn analysis of SaO(2) data obtained from pulse oximetric recordings could be useful as a diagnostic technique for OSA subjects.

A survey of transcutaneous blood gas monitoring among European neonatal intensive care units.

BACKGROUND: PCO2 and PO2 are important monitoring parameters in neonatal intensive care units (NICU). Compared to conventional blood gas measurements that cause significant blood loss in preterms, transcutaneous (tc) measurements allow continuous, non-invasive monitoring of blood gas levels. The aim of the study was to survey the usage and opinions among German speaking NICUs concerning tc blood gas monitoring. METHODS: A questionnaire was developed and sent to 56 head nurses of different NICUs in Germany, Switzerland and Austria. RESULTS: A completely answered questionnaire was obtained from 41 NICUs. In two of these units tc measurements are not performed. In most NICUs (77%), both PtcO2 and PtcCO2 are measured simultaneously. Most units change the sensors every 3 hours; however, the recommended temperature of 44 degrees C is used in only 15% of units. In only 8% of units are arterial blood gases obtained to validate tc values. Large variations were found concerning the targeted level of oxygen saturation [median upper limit: 95% (range 80-100%); median lower limit: 86% (range 75-93%)] and PO2 [median upper limit: 70 mmHg (range 45-90 mmHg); median lower limit: 44 mmHg (range 30-60 mmHg)]. CONCLUSION: Our survey shows that the use of tc monitors remains widespread among German speaking NICUs, despite earlier data suggesting that their use had been abandoned in many NICUs worldwide. In addition, we suggest that the current method of monitoring oxygenation may not prevent hyperoxemia in preterm infants.