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Today, there is no continuous monitoring of the bronchial epithelial lining fluid. This study used microdialysis as a method of continuous monitoring of early lung cytokine response secondary to intestinal ischemia-reperfusion in pigs. The authors aimed to examine bronchial microdialysis for continuous monitoring of IL-1β, TNF-α, IL-8, and fluorescein isothiocyanate Dextran 4,000 Da (FD-4). The superior mesenteric artery was cross-clamped for 120 min followed by 240 min of reperfusion (ischemia group, n = 8). Four sham-operated pigs served as controls. The pigs were anesthetized and normoventilated (peak inspiratory pressure, <20 cm H2O; positive end-expiratory pressure, 7 cm H2O). Samples from bronchial and luminal intestinal and arterial microdialysis catheters (flow-rate of 1 μL/min) were collected during reperfusion in 60-min fractions. Samples were analyzed for TNF-α, IL-1β, IL-8, and FD-4. Data are presented as median (interquartile range). A lung biopsy was collected at the end of the experiment. During reperfusion, there was an increase in bronchial concentrations of both IL-8 (3.70 [1.47-8.93] ng/mL per h vs. controls, 0.61 [0.47-0.91] ng/mL per h; P < 0.001) and IL-1β (0.32 [0.05-0.56] ng/mL per h vs. controls, 0.07 [0.04-0.10] ng/mL per h; P = 0.008). In the intestinal lumen, IL-8 was increased in the ischemia group (6.33 [3.13-9.23] ng/mL per h vs. controls, 0.89 [0.21-1.86] ng/mL per h; P < 0.001). The FD-4 did not differ between groups. Pulmonary vascular resistance and pulmonary shunt increased versus controls. During reperfusion, PaO2/FiO2 ratio decreased in the ischemia group. Histology was normal in both groups. Bronchial microdialysis detects altered levels of cytokines in the epithelial lining fluid and can be used for continuous monitoring of the immediate local lung cytokine response secondary to intestinal ischemia-reperfusion.

Background: Contents of the epithelial lining fluid (ELF) of the bronchi are of central interest in lung diseases, acute lung injury and pharmacology. The most commonly used technique broncheoalveolar lavage is invasive and may cause lung injury. Microdialysis (MD) is a method for continuous sampling of extracellular molecules in the immediate surroundings of the catheter. Urea is used as an endogenous marker of dilution in samples collected from the ELF. The aim of this study was to evaluate bronchial MD as a continuous monitor of the ELF.

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Aortic surgery results in ischemia–reperfusion injury that induces an inflammatory response and frequent complications. The magnitude of the inflammatory response in blood and bronchi may be associated with the risk of immediate complications. The purpose of the study was to evaluate bronchial microdialysis as a continuous monitoring of cytokines in bronchial epithelial lining fluid (ELF) and to determine whether bronchial ELF cytokine levels reflect the ischemia–reperfusion injury and risk for complications during open abdominal aortic aneurysm (AAA) repair. We measured cytokines in venous blood using microdialysis and in serum for comparison. Sixteen patients scheduled for elective open AAA repair were included in a prospective observational study. Microdialysis catheters were introduced into a bronchi and a cubital vein. Eighteen cytokines were measured using a Bio‐Plex Magnetic Human Cytokine Panel. Samples were collected before and during cross‐clamping of the aorta as well as from 0 to 60 min and from 60 to 120 min of reperfusion. The ELF levels of several cytokines changed significantly during reperfusion. In particular, IL‐6 increased more than 10‐fold and IL‐13 more than 5‐fold during ischemia and reperfusion. Also, the venous levels of several inflammatory and anti‐inflammatory cytokines increased and exhibited their highest concentration during reperfusion. Both bronchial and venous cytokine levels correlated with duration of the procedure, intensive care days, and preoperative kidney disease. Three patients suffered organ failure as a direct consequence of the procedure, and in these patients the bronchial ELF concentrations of 17 of 18 cytokines differed significantly from patients without such complications. Bronchial microdialysis is suited for continuous monitoring of inflammation during open AAA repair. The bronchial ELF cytokine levels may be useful in predicting immediate complications such as organ failure in patients undergoing vascular surgery.

Admittance to a high dependency unit (HDU) is expensive. Patients who receive surgical treatment with 'low anterior resection of the rectum' (LAR) or 'abdominoperineal resection of the rectum' (APR) at our hospital are routinely treated in an HDU the first 16-24 h of the postoperative (PO) period. The aim of this study was to describe the extent of HDU-specific interventions given. We included patients treated with LAR or APR at the St. Olav University Hospital (Trondheim, Norway) over a 1-year period. Physiologic data and HDU-interventions recorded during the PO-period were obtained from the anesthesia information management system (AIMS). HDU-specific interventions were defined as the need for respiratory support, fluid replacement therapy >500 ml/h, vasoactive medications, or a need for high dose opioids (morphine >7.5 mg/h i.v.). Sixty-two patients were included. Most patients needed HDU-specific interventions during the first 6 h of the PO period. After this, one-third of the patients needed one or more of the HDU-specific interventions for shorter periods of time. Another one-third of the patients had a need for HDU-specific therapies for more than ten consecutive hours, primarily an infusion of nor-epinephrine. Most patients treated with LAR or APR was in need of an HDU-specific intervention during the first 6 h of the PO-period, with a marked decline after this time period. The applied methodology, using an AIMS, demonstrates that there is great variability in individual patients' postoperative needs after major surgery, and that these needs are dynamic in their nature.

The gold standard for assessing sleep apnea, polysomnography, is resource intensive and inconvenient. Thus, several simpler alternatives have been proposed. However, validations of these alternatives have focused primarily on estimating the apnea-hypopnea index (apnea events per hour of sleep), which means information, clearly important from a physiological point of view such as apnea type, apnea duration, and temporal distribution of events, is lost. The purpose of the present study was to investigate if this information could also be provided with the combination of radar technology and pulse oximetry by classifying sleep apnea events on a second-by-second basis. Fourteen patients referred to home sleep apnea testing by their medical doctor were enrolled in the study (6 controls and 8 patients with sleep apnea; 4 mild, 2 moderate, and 2 severe) and monitored by Somnofy (radar-based sleep monitor) in parallel with respiratory polygraphy. A neural network was trained on data from Somnofy and pulse oximetry against the polygraphy scorings using leave-one-subject-out cross-validation. Cohen’s kappa for second-by-second classifications of no event/event was 0.81, or almost perfect agreement. For classifying no event/hypopnea/apnea and no event/hypopnea/obstructive apnea/central apnea/mixed apnea, Cohen’s kappa was 0.43 (moderate agreement) and 0.36 (fair agreement), respectively. The Bland-Altman 95% limits of agreement for the respiratory event index (apnea events per hour of recording) were -8.25 and 7.47, and all participants were correctly classified in terms of sleep apnea severity. Furthermore, the results showed that the combination of radar and pulse oximetry could be more accurate than the two technologies separately. Overall, the results indicate that radar technology and pulse oximetry could reliably provide information on a second-by-second basis for no event/event which could be valuable for management of sleep apnea. To be clinically useful, a larger study is necessary to validate the algorithm on a general population.

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