Is continuous transcutaneous monitoring of PCO2 (TcPCO2) over 8 h reliable in adults?

Monitoring of non-invasive ventilation (NIV) in a non-intensive care unit (non-ICU) setting requires a method of evaluating nocturnal PaCO2, such as transcutaneous CO2 monitoring (TcPCO2). However, changing the probe site after 4 h and recalibrating (as recommended) is time-consuming and impractical. Continuous (8-h) TcPCO2 monitoring at a lower electrode temperature (43 degrees C) in this setting has never been formally studied. Patients under intermittent NIV were studied (n = 28, aged 69 +/- 9 years, PaO2: 71 +/- 13 mmHg, PaCO2: 49 +/- 9 mmHg). After calibration and stabilization of TcPCO2 (Radiometer Tina TCM3 capnograph), arterial blood gases (ABG) were measured and compared with transcutaneous readings. In 10 patients who underwent continuous 8-h TcPCO2 recording, ABGs were also measured after 4 and 8 h. The correlation between TcPCO2 and PaCO2 was highly significant (r2 = 0.92, P<0.0001). Mean (TcPCO2 PaCO2) gradient (bias) was: -2.8 +/- 3.8 mmHg; limits of agreement were: (-10.4; +4.8 mmHg). TcPCO2-PaCO2 gradient was lowest (i.e. within-bias +/- 2 mmHg) between 40 and 54 mmHg, increasing below and above these values. Over 8 h, no significant drift of the TcPCO2 signal occurred (ANOVA). No discomfort or skin lesion was noted. In conclusion, with an electrode temperature of 43 degrees C, 8-h continuous monitoring of TcPCO2 was well tolerated, without any local side-effects or significant drift of TcPCO2 signal; when compared to previous reports, lowering the electrode temperature did not decrease performance for CO2 monitoring.     

Is intensive monitoring during the first transfusion in pediatric patients necessary?

Background

Some pediatric patients, typically those that are very young or felt to be especially sick are temporarily admitted to the intensive care unit (ICU) for observation during their first transfusion. If a significant reaction that requires ICU management does not occur, these patients are then transferred to a regular ward where future blood products are administered. The aim of this project was to determine if heightened observation such as temporary ICU admissions for the first transfusion are warranted.

Methods

From the blood bank records of a tertiary care pediatric hospital, a list of patients on whom a transfusion reaction was reported between 2007 and 2012, the type of reaction and the patient's transfusion history, were extracted. The hospital location where the transfusion occurred, and whether the patient was evaluated by the ICU team or transferred to the ICU for management of the reaction was determined from the patient's electronic medical record.

Results

There were 174 acute reactions in 150 patients. Of these 150 patients, 13 (8.7%) different patients experienced a reaction during their first transfusion; all 13 patients experienced clinically mild reactions (8 febrile non-hemolytic, 4 mild allergic, and 1 patient who simultaneously had a mild allergic and a febrile non-hemolytic), and none required ICU management. Six severe reactions (6 of 174, 3.4%) involving significant hypotension and/or hypoxia that required acute and intensive management occurred during subsequent (i.e. not the first) transfusion in six patients.

Conclusions

The practice of intensive observation for the first transfusion in pediatric patients is probably unnecessary.     

Does sleep apnea increase the risk of cardiorespiratory complications during endoscopy procedures?

Background  

Patients with obstructive sleep apnea (OSA) have an increased risk of perioperative complications.     

Dynamic behavior during noninvasive ventilation: chaotic support?

Acute noninvasive ventilation is generally applied via face mask, with modified pressure support used as the initial mode to assist ventilation. Although an adequate seal can usually be obtained, leaks frequently develop between the mask and the patient's face. This leakage presents a theoretical problem, since the inspiratory phase of pressure support terminates when flow falls to a predetermined fraction of peak inspiratory flow. To explore the issue of mask leakage and machine performance, we used a mathematical model to investigate the dynamic behavior of pressure-supported noninvasive ventilation, and confirmed the predicted behavior through use of a test lung. Our mathematical and laboratory analyses indicate that even when subject effort is unvarying, pressure-support ventilation applied in the presence of an inspiratory leak proximal to the airway opening can be accompanied by marked variations in duration of the inspiratory phase and in autoPEEP. The unstable behavior was observed in the simplest plausible mathematical models, and occurred at impedance values and ventilator settings that are clinically realistic.     

Is the plasma ACTH concentration a reliable parameter in the insulin tolerance test?

OBJECTIVE: The insulin tolerance test (ITT) is an established standardized test for the evaluation of the hypothalamic-pituitary-adrenal axis. While a peak cortisol value of >18 microg/dl is usually interpreted as a sufficient response to the ITT, the plasma ACTH response has not yet been standardized. METHODS: We evaluated retrospectively the peak plasma ACTH concentrations during 140 ITTs in 125 patients with suspected pituitary insufficiency and prospectively in 15 healthy subjects. RESULTS: All healthy subjects had a peak cortisol concentration >/=18 microg/dl; 32 of 125 tests in the patients showed an insufficient cortisol response (peak cortisol concentration <18 microg/dl). The peak stimulated ACTH concentration in patients with secondary adrenal insufficiency (SAI) was 49.2+/-37.2 pg/ml (mean+/-s.d.) vs 130.9+/-89.3 pg/ml in patients without SAI, and 110.9+/-55.4 pg/ml in normal subjects (P<0.001). There was a weak, but significantly positive correlation between the peak ACTH and peak cortisol concentrations (rho=0.446, P<0.001), but there was also a very wide spread of the values. Defining a cut-off value for the peak plasma ACTH concentration with a sufficient sensitivity and specificity to identify patients with an impaired hypothalamic-pituitary-adrenal (HPA) axis was not possible. A peak plasma ACTH <20 pg/ml as a cut-off value had a sensitivity of 25% and a specificity of 98% for SAI. A cut-off value of a peak plasma ACTH <140 pg/ml had a sensitivity of 97% but a low specificity of 39%. CONCLUSIONS: Although there is a significant positive correlation between the peak ACTH and the peak cortisol concentrations, we conclude that there is no additional benefit in determining the ACTH concentrations during an ITT. Because of the strong variations of the values, the peak ACTH concentration is a poor parameter for the evaluation of the HPA axis.     

Evidence for continuous glucose monitoring: sufficient for reimbursement?

Evidence for continuous glucose monitoring is mounting. Meta‐analyses consistently show lowering of HbA_1c, and the first trial reporting a reduction in severe hypoglycaemic events in patients with hypoglycaemia unawareness has recently been presented. The more recent trials studied larger numbers of patients and may have shown better results because of improved technology. The various combinations of pump and sensor, with automated bolus calculators and low glucose suspend features, make evaluation more challenging from a reimbursement point of view, but evidence seems convincing enough to justify reimbursement for selected patient groups, including those who have shown a substantial improvement in HbA_1c during a trial period, and those with hypoglycaemia unawareness who encountered severe hypoglycaemia in the recent past. More data on cost–efficacy are needed.     

Is blood pressure during the night more predictive of cardiovascular outcome than during the day?

The objective of this study was to investigate the prognostic significance of the ambulatory blood pressure (BP) during night and day and of the night-to-day BP ratio (NDR). We studied 7458 participants (mean age 56.8 years; 45.8% women) enrolled in the International Database on Ambulatory BP in relation to Cardiovascular Outcome. Using Cox models, we calculated hazard ratios (HR) adjusted for cohort and cardiovascular risk factors. Over 9.6 years (median), 983 deaths and 943 cardiovascular events occurred. Nighttime BP predicted mortality outcomes (HR, 1.18-1.24; P<0.01) independent of daytime BP. Conversely, daytime systolic (HR, 0.84; P<0.01) and diastolic BP (HR, 0.88; P<0.05) predicted only noncardiovascular mortality after adjustment for nighttime BP. Both daytime BP and nighttime BP consistently predicted all cardiovascular events (HR, 1.11-1.33; P<0.05) and stroke (HR, 1.21-1.47; P<0.01). Daytime BP lost its prognostic significance for cardiovascular events in patients on antihypertensive treatment. Adjusted for the 24-h BP, NDR predicted mortality (P<0.05), but not fatal combined with nonfatal events. Participants with systolic NDR of at least 1 compared with participants with normal NDR (> or = 0.80 to <0.90) were older, at higher risk of death, but died at higher age. The predictive accuracy of the daytime and nighttime BP and the NDR depended on the disease outcome under study. The increased mortality in patients with higher NDR probably indicates reverse causality. Our findings support recording the ambulatory BP during the whole day.     

Can ambulatory blood-pressure monitoring provide reliable indices of arterial stiffness?

BACKGROUND: The use of ambulatory recordings of blood pressure (BP) was proposed to estimate arterial stiffness (AS). We compared the relative value of the ambulatory AS index (AASI), and of the slope of pulse pressure (PP) according to mean BP (MBP) obtained from 24-h ambulatory BP monitoring, to the monitoring of the arrival time of Korotkoff sounds (QKD interval) in the prediction of cardiovascular (CV) events. METHODS: Twenty-four-hour ambulatory BP and QKD monitoring were recorded at baseline, before antihypertensive treatment of hypertensive patients in our Bordeaux cohort. From these recordings, the AASI, the PP/MBP slope, and the theoretical value of the QKD for a systolic pressure of 100 mm Hg and a heart rate of 60 beats/min (QKD100-60) were calculated. The patients were then given antihypertensive treatment and followed by their family physicians, who were unaware of the QKD, AASI, and PP/MBP slope results. Regular updates on patients were obtained. The reproducibility of measurements was studied in 38 normal subjects evaluated on two occasions. RESULTS: The reproducibility of the AASI and the PP/MBP slope was less than that of BP over 24 h and of QKD100-60. The cohort comprised 469 patients. With an average follow-up of 70+/-39 months, 62 CV complications, including 13 deaths, were recorded. In the monovariate analysis, age, PP over 24 h, QKD100-60, AASI, and the PP/MBP slope were significantly related to the occurrence of complications. In the multivariate analysis, when age and PP over 24 were included in the model, only QKD100-60 remained significantly linked to CV events. CONCLUSIONS: Our data support the value of the AASI as an indirect estimate of AS and as an element in the evaluation of CV risk in hypertensive patients. However, the reproducibility of this index is less, and its predictive value for complications is poorer, than that of QKD100-60, a parameter that we believe is more closely linked to AS.