A systematic review of the effects of temperature and precipitation on pollen concentrations and season timing, and implications for human health.

Climate and weather directly impact plant phenology, affecting airborne pollen. The objective of this systematic review is to examine the impacts of meteorological variables on airborne pollen concentrations and pollen season timing. Using PRISMA methodology, we reviewed literature that assessed whether there was a relationship between local temperature and precipitation and measured airborne pollen. The search strategy included terms related to pollen, trends or measurements, and season timing. For inclusion, studies must have conducted a correlation analysis of at least 5 years of airborne pollen data to local meteorological data and report quantitative results. Data from peer-reviewed articles were extracted on the correlations between seven pollen indicators (main pollen season start date, end date, peak date, and length, annual pollen integral, average daily pollen concentration, and peak pollen concentration), and two meteorological variables (temperature and precipitation). Ninety-three articles were included in the analysis out of 9,679 articles screened. Overall, warmer temperatures correlated with earlier and longer pollen seasons and higher pollen concentrations. Precipitation had varying effects on pollen concentration and pollen season timing indicators. Increased precipitation may have a short-term effect causing low pollen concentrations potentially due to "wash out" effect. Long-term effects of precipitation varied for trees and weeds and had a positive correlation with grass pollen levels. With increases in temperature due to climate change, pollen seasons for some taxa in some regions may start earlier, last longer, and be more intense, which may be associated with adverse health impacts, as pollen exposure has well-known health effects in sensitized individuals.

Acute Endovascular Stroke Treatment in Germany in 2019 : Results from a Nationwide Database.

PURPOSE: Since the incidental discovery and systematic introduction of mechanical endovascular stroke treatment in 2015 there are few reports about the real-life situation in daily clinical practice. The aim of this study was to evaluate the mechanical thrombectomy data documented in the quality assurance database of the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR) and the German Society of Neuroradiology (DGNR) in 2019. METHODS: We retrospectively analyzed the clinical and procedural data of all mechanical thrombectomies that were entered into the voluntary nationwide database in 2019. The information of each procedure was provided on a standardized web-based data sheet. Data were exported and analyzed by a group of experts on behalf of the DGNR. RESULTS: A total of 13,840 data sets from 158 participating centers could be analyzed. Mean age of the patients was 74 ± 13 years; 53.9% were female. Vessel occlusion was located in the anterior circulation in 87.4%, in the posterior circulation in 10.7%. On hospital admission, the median National Institutes of Health Stroke Scale (NIHSS) was 14 (lower/upper quartile 10/19); at hospital discharge, median NIHSS had dropped to 9 (lower/upper quartile 2/12; p < 0.001). Recanalization of the occluded vessel segment was successful (TICI 2b + 3) in 88.4%. The reported complication rate was 7.3%, with subarachnoid hemorrhage as the most frequent complication (3.4%), followed by parenchymal hemorrhage (1.7%) and embolization in new territories (1.2%). Overall, the median time interval from symptom onset to hospital admission was 94 min (quartiles 59/180 min), the median time from hospital admission to groin puncture was 74 min (lower/upper quartile 47/103 min), and the median duration of the procedure 43 min (lower/upper quartile 25.2/73.2 min). A comparison between primary and secondary referral revealed a significant faster symptom-to-intervention time for primary referrals, whereas in-house workflows showed no significant difference. CONCLUSION: The analysis represents the largest documented cohort of acute stroke patients treated by thrombectomy. The documentation allows for a detailed evaluation of procedural, clinical, logistic and radiation exposure data and might be used for monitoring the quality of the treatment on a nationwide scale.

Transesophageal Echocardiography - Dysphagia Risk in Acute Stroke (TEDRAS): a prospective, blind, randomized and controlled clinical trial.

BACKGROUND AND PURPOSE: Dysphagia is common in acute stroke and leads to worse overall outcome. Transesophageal echocardiography (TEE) is used in the diagnostic evaluation of stroke with regard to its etiology and is a known cause of postoperative dysphagia in cardiac surgery. The prevalence of dysphagia in acute stroke patients undergoing TEE remains unknown. The aim of the Transesophageal Echocardiography - Dysphagia Risk in Acute Stroke (TEDRAS) study was to assess the influence of TEE on swallowing among patients who have experienced acute stroke. METHODS: The TEDRAS study was a prospective, blind, randomized, controlled trial that included two groups of patients with acute stroke. Simple unrestricted randomization was performed, and examiners were blinded to each other's results. Swallowing was tested using flexible endoscopic evaluation of swallowing (FEES) at three different time points in the intervention group (24 h before, immediately after and 24 h after TEE) and in the control group (FEES on three consecutive days and TEE earliest after the third FEES). Validated scales were used to assess dysphagia severity for all time points as primary outcome measures. RESULTS: A total of 34 patients were randomized: 19 to the intervention group and 15 to the control group. The key findings of the repeated-measures between-group comparisons were significant increases in the intervention group for the following dysphagia measures: (1) secretion severity score (immediately after TEE: P < 0.001; 24 h after TEE: P < 0.001) and (2) Penetration-Aspiration Scale score for saliva (immediately after TEE: P < 0.001; 24 h after TEE: P = 0.007), for small (immediately after TEE: P = 0.009) and large liquid boli (immediately after TEE: P = 0.009; 24 h after TEE: P = 0.025). CONCLUSION: The results indicate a negative influence of TEE on swallowing in acute stroke patients for at least 24 hours.

Randomized Trial of 2 Self-Titrated Oral Appliances for Airway Management.

The effectiveness and predictability of 2 different oral appliance (OA) designs to reduce the respiratory event index (REI) in moderate and severe obstructive sleep apnea (OSA) patients requires elucidation. The primary aim of the trial was to determine if 2 widely used midline-traction and bilateral-thrust OA designs differ in effectiveness to reduce the REI within a single test population categorized by OSA severity. Moderate and severe adult OSA patients, who were previously prescribed continuous positive airway pressure therapy (CPAP) but were dissatisfied with it (n = 56), were studied by home-polygraphy in a randomized crossover trial using either midline-traction with restricted mouth opening (MR) or bilateral thrust with opening permitted (BP) design OAs. OAs were used nightly for 4 wk (T2) followed by a 1-wk washout period, then 4 wk (T4) using the alternate OA. REI and oxygen saturation (SaO2) were primary outcomes, while predictability and efficacy comparison of the 2 OAs were secondary outcomes. Thirty-six participants had used MR and BP OAs during both 4-wk study legs. Twenty (55.6%) MR OA-using participants, 25 (69.4%) BP OA-using participants, and 16 (44.4%) participants using both OAs had significant REI reductions. Overall baseline (T0) median REI (interquartile range) of 33.7 (20.7-54.9) was reduced to 18.0 (8.5-19.4) at T2 and to 12.5 (8.2-15.9) at T4 (P < 0.001). Comparison of the 2 sequence groups' (MR-BP and BP-MR) REI showed the median differences between T0 and T2 and T4 were highly significant (P < 0.001). Regression analysis predicted about half of all users will have REIs between 8 and 16 after 2 mo. Baseline overjet measures >2.9 mm predicted greater OA advancement at T4. Mean and minimum SaO2 did not change significantly from T0 to T2 or T4. MR and BP OA designs similarly attenuated REI in moderate and severe OSA individuals who completed the 8-wk study protocol with greater REI reduction in those with severe OSA (ClinicalTrials.gov NCT03219034).

Cerebral oxygen saturation and cardiac output during anaesthesia in sitting position for neurosurgical procedures: a prospective observational study.

BACKGROUND: Neurosurgical operations in the dorsal cranium often require the patient to be positioned in a sitting position. This can be associated with decreased cardiac output and cerebral hypoperfusion, and possibly, inadequate cerebral oxygenation. In the present study, cerebral oxygen saturation was measured during neurosurgery in the sitting position and correlated with cardiac output. METHODS: Perioperative cerebral oxygen saturation was measured continuously with two different monitors, INVOS® and FORE-SIGHT®. Cardiac output was measured at eight predefined time points using transoesophageal echocardiography. RESULTS: Forty patients were enrolled, but only 35 (20 female) were eventually operated on in the sitting position. At the first time point, the regional cerebral oxygen saturation measured with INVOS® was 70 (sd 9)%; thereafter, it increased by 0.0187% min-1 (P<0.01). The cerebral tissue oxygen saturation measured with FORE-SIGHT® started at 68 (sd 13)% and increased by 0.0142% min-1 (P<0.01). The mean arterial blood pressure did not change. Cardiac output was between 6.3 (sd 1.3) and 7.2 (1.8) litre min-1 at the predefined time points. Cardiac output, but not mean arterial blood pressure, showed a positive and significant correlation with cerebral oxygen saturation. CONCLUSIONS: During neurosurgery in the sitting position, the cerebral oxygen saturation slowly increases and, therefore, this position seems to be safe with regard to cerebral oxygen saturation. Cerebral oxygen saturation is stable because of constant CO and MAP, while the influence of CO on cerebral oxygen saturation seems to be more relevant. CLINICAL TRIAL REGISTRATION: NCT01275898.

An Appeal to Standardize CT- and MR-Perfusion.

Multiple treatment options and risk assessment in cerebrovascular diseases are the actual challenges in diagnostic as well as in interventional neuroradiology.Acute ischemic stroke essentially requires rapid detection of the location and extent of infarction and tissue at risk for making treatment decisions. In the acute setting, modern multiparametric perfusion imaging protocols help to determine infarct core and adjacent penumbral tissue, and they enable the estimation of collateral flow of intra- and extracranial arteries. In subacute delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) or chronic occlusive neurovascular diseases estimation of residual and collateral flow may be even more difficult.Prediction of sufficient or insufficient supply of brain tissue may be essential to balance conservative against interventional therapies. However, so far no established reliable thresholds are available for determining tissue at acute, subacute, chronic progressive, or chronic risk.Reliable and reproducible thresholds require quantitative perfusion measurements with a calibrated instrument. But the measurement instrument is not at all defined-a variety of parameter settings, different algorithms based on multiple assumptions and a wide variety of published normal and pathologic values for perfusion parameters indicate the problem. In the following text, we explain how deep the problem may be enrooted within techniques and algorithms impeding broad use of perfusion for many clinical issues.

Volume perfusion CT (VPCT) for the differential diagnosis of patients with suspected cerebral vasospasm: qualitative and quantitative analysis of 3D parameter maps.

OBJECT: Cerebral vasospasm (CV) following subarachnoid hemorrhage (SAH) implies high risk for secondary ischemia. It requires early diagnosis to start treatment on time. We aimed to assess the utility of "whole brain" VPCT for detecting localization and characteristics of arterial vasospasm. METHODS: 23 patients received a non-enhanced CT, VPCT and CTA of the brain. The distribution of ischemic lesions was analyzed on 3D-perfusion-parameter-maps of CBF, CBV, MTT, TTS, TTP, and TTD. CT-angiographic axial and coronal maximum-intensity-projections were reconstructed to determine arterial vasospasm. CT-data was compared to DSA, if performed additionally. Volume-of-interest placement was used to obtain quantitative mean VPCT values. RESULTS: 82% patients (n=19) had focal cerebral hypoperfusion. 100% sensitivity and 100% specificity was found for TTS (median 1.9s), MTT (median 5.9s) and TTD (median 7.6s). CBV showed no significant differences. In 78% (n=18) focal vessel aberrations could be detected either on CTA or DSA or on both. CONCLUSION: VPCT is a non-invasive method with the ability to detect focal perfusion deficits almost in the whole brain. While DSA remains to be the gold standard for detection of CV, VPCT has the potential to improve noninvasive diagnosis and treatment decisions.

Time course of cerebrovascular autoregulation during extreme Trendelenburg position for robotic-assisted prostatic surgery.

Trendelenburg positioning in combination with pneumoperitoneum during robotic-assisted prostatic surgery possibly impairs cerebrovascular autoregulation. If cerebrovascular autoregulation is disturbed, arterial hypertension might induce cerebral hyperaemia and brain oedema, while low arterial blood pressure can induce cerebral ischaemia. The time course of cerebrovascular autoregulation was investigated during use of the Trendelenburg position and a pneumoperitoneum for robotic-assisted prostatic surgery using transcranial Doppler ultrasound. Cerebral blood flow velocity was correlated with arterial blood pressure and the autoregulation index (Mx) was calculated. In 23 male patients, Mx was assessed at baseline, after induction of general anaesthesia, during the Trendelenburg position (40-45°), and after repositioning. During the Trendelenburg position, Mx increased over time, indicating an impairment of cerebrovascular autoregulation. After repositioning, Mx recovered to baseline levels. It can be concluded that with longer durations of Trendelenburg position and pneumoperitoneum, cerebrovascular autoregulation deteriorates, and, therefore, blood pressure management should be adapted to avoid cerebral oedema and the duration of Trendelenburg position should be as short as possible.

4D CT angiography more closely defines intracranial thrombus burden than single-phase CT angiography.

BACKGROUND AND PURPOSE: In patients with acute stroke, the location and extent of intravascular thrombi correlate with clinical and imaging outcomes and have been used to predict the success of intravenous thrombolysis. We hypothesized that 4D-CTA reconstructed from whole-brain CTP more closely outlines intracranial thrombi than conventional single-phase CTA. MATERIALS AND METHODS: Sixty-seven patients with anterior circulation occlusion were retrospectively analyzed. For 4D-CTA, temporal maximum intensity projections were calculated that combine all 30 spiral scans of the CTP examination through temporal fusion. Thrombus extent was assessed by a semi-quantitative clot burden score (0-10; in which 0 = complete unilateral anterior circulation occlusion and 10 = patent vasculature). In patients with sufficient collateral flow, the length of the filling defect and corresponding hyperdense middle cerebral artery sign on NCCT were measured. RESULTS: Clot burden on temporal maximum intensity projection (median clot burden score, 7.0; interquartile range, 5.1-8.0) was significantly lower than on single-phase CT angiography (median, 6.0; interquartile range, 4.5-7.0; P < .0001). The length of the hyperdense middle cerebral artery sign (14.30 ± 5.93 mm) showed excellent correlation with the filling defect in the middle cerebral artery on temporal maximum intensity projection (13.40 ± 6.40 mm); this filling defect was larger on single-phase CT angiography (18.08 ± 6.54 mm; P = .043). CONCLUSIONS: As the result of an increased sensitivity for collateral flow, 4D-CTA temporal maximum intensity projection more closely outlines intracranial thrombi than conventional single-phase CT angiography. Our findings can be helpful when planning acute neurointervention. Further research is necessary to validate our data and assess the use of 4D-CTA in predicting response to different recanalization strategies.

[The first 24 hours: acute dyspnea]. / Die ersten 24 Stunden: Die akute Dyspnoe.

Acute dyspnea is a common presentation in the emergency department. Immediate diagnostic strategy and efficient management is crucial. Therefore, a diagnostic work up consisting of a brief medical history, physical examination and technical investigations, including laboratory tests, is presented. Identification of the cardio-vascular, pulmonary or other etiology enables the initiation of adequate therapy. This is outlined in detail for three common entities.

Human cerebral microcirculation and oxygen saturation during propofol-induced reduction of bispectral index.

BACKGROUND: Propofol reduces cerebral blood flow (CBF) secondary to cerebral metabolic depression. However, in vitro and in vivo studies demonstrate that propofol directly dilates the vascular smooth muscle. This study investigates the effects of propofol-induced changes in bispectral index (BIS) on cerebral microcirculation and oxygenation during craniotomies. METHODS: In 21 craniotomy patients undergoing routine craniotomy, anaesthesia was maintained with propofol 4-10 mg kg⁻¹ h⁻¹ and remifentanil 0.1-0.4 µg kg⁻¹ min⁻¹. Propofol concentration was adjusted to achieve higher BIS (target 40) or lower BIS (target 20). Regional measurements of capillary venous blood flow (rvCBF), oxygen saturation (srvO2), and haemoglobin amount (rvHb) at 2 mm (grey matter) and 8 mm (white matter) cerebral depth were randomly performed at higher and lower BIS by combined laser-Doppler flowmetry and spectroscopy. Calculations: approximated arteriovenous difference in oxygen content (avDO2) and cerebral metabolic rate of oxygen (aCMRO2). RESULTS: mean values (sd). STATISTICS: Mann-Whitney test (*P<0.05). Results Human cerebral microcirculation and oxygen saturation were assessed at propofol dosages 5.1 (2.3) mg kg⁻¹ h⁻¹ [BIS 40 (9)] and 7.8 (2.1) mg kg⁻¹ h⁻¹ [BIS 21 (7)]. Propofol-induced reduction in BIS resulted in increased srvO2 (P=0.018), and decreased avDO2 (P=0.025) and aCMRO(2) (P=0.022), in 2 mm cerebral depth, while rvCBF and rvHb remained unchanged. In 8 mm cerebral depth, srvO2, rvCBF, rvHb, and also calculated parameters avDO2 and aCMRO2 remained unaltered. CONCLUSIONS: Findings suggest alteration of the CBF/CMRO2 ratio by propofol in cortical brain regions; therefore, it might be possible that propofol affects coupling of flow and metabolism in the cerebral microcirculation.

Feasibility of flat panel angiographic CT after intravenous contrast agent application in the postoperative evaluation of patients with clipped aneurysms.

BACKGROUND AND PURPOSE: Important findings, such as aneurysm remnants or major arterial occlusion, can be detected on intra- or postoperative angiography after surgical clipping of intracranial aneurysms. The purpose of this study was to evaluate the feasibility of IV-ACT for the postoperative detection of residual aneurysms and parent vessel patency compared with IA-DSA, which was selected as the standard reference method. MATERIALS AND METHODS: Twenty-two patients with 27 aneurysms treated by surgical clipping were examined by using both IA-DSA and IV-ACT. Both diagnostic procedures were performed on an FPD-equipped angiography system. Postprocessing of IV-ACT acquisitions was performed on a dedicated workstation producing multiplanar reformations and maximum intensity projections of the clip region and other intracranial arteries. Three interventional neuroradiologists independently evaluated both procedures. RESULTS: A residual aneurysm was delineated in 10 cases with IA-DSA. Sufficient opacification of the intracranial vessels was assigned in 26 IV-ACT cases. Due to metal artifacts, IV-ACT images were tagged as "not diagnostic" on 8 occasions. In the other 19 aneurysms, a residual aneurysm was delineated in 6 cases-all 6 being true-positive compared with IA-DSA-and was excluded in the remaining 13 cases-all true-negative. Even small aneurysm remnants with a diameter of 1.5 mm were detected with IV-ACT. CONCLUSIONS: Currently IV-ACT cannot be recommended as a routine tool for postoperative evaluation of clipped aneurysms due to metal artifacts in 30% of the examinations. These artifacts appear with multiple normal-sized or large clips. In patients with single or multiple small clips, IV-ACT can reliably show aneurysm remnants.

Angiographic CT after intravenous contrast agent application: A noninvasive follow-up tool after intracranial angioplasty and stenting.

BACKGROUND AND PURPOSE: ICAS is one of the therapeutic options in symptomatic cerebral artery stenosis. iaDSA is the current criterion standard examination after ICAS for the detection of ISR. In this study, we evaluated ivACT as a potential noninvasive follow-up alternative. MATERIALS AND METHODS: In 17 cases, ivACT and iaDSA were performed after ICAS. Both procedures were carried out on a flat-panel-detector-equipped angiography system. Postprocessing of ivACT acquisitions was performed on a dedicated workstation producing multiplanar reformations of the stent region and other intracranial arteries. Restenotic lesions were compared with iaDSA measurements. All studies were independently evaluated by 2 experienced neuroradiologists blinded to patients data. RESULTS: In 5 cases, ISR was diagnosed on iaDSA images. All restenotic lesions were reliably detected (sensitivity, 100%; 95%CI, 48%-100%) and could be correctly quantified on ivACT images in comparison with iaDSA. The neuroradiologists correctly excluded ISR in 11 of 12 lesions after viewing the ivACT examinations (specificity, 92%; 95%CI, 62%-100%). Measurements of ISR on ivACT were highly correlated to iaDSA (Pearson r = 0.94, P < .01). CONCLUSIONS: IvACT is a promising noninvasive follow-up examination after ICAS. With its high spatial resolution, it can reliably detect or exclude ISR. Contrary to iaDSA, there is no need for a recovery period after ivACT and the risk of neurologic complications is practically lowered to zero.

Feasibility of angiographic CT in peri-interventional diagnostic imaging: a comparative study with multidetector CT.

BACKGROUND AND PURPOSE: The ability to perform neuroimaging on the angiography suite is important in making decisions during neurointerventions. Our aim was the evaluation of ACT as a fast available diagnostic tool during and after neuroendovascular procedures and the comparison of ACT with postinterventional MDCT. MATERIALS AND METHODS: Eighty-four peri-interventional ACT acquisitions were obtained and evaluated: 38 after coil embolization of cerebral aneurysms, 16 after intracranial angioplasty with stent placement, and 30 after endovascular mechanical thrombectomy and lysis. Interventions and ACTs were performed on a biplane angiography system equipped with flat panel detectors. Postprocessing was performed on a dedicated workstation, and multiplanar reformations were generated. Reference studies were performed on a 16- or 128-section MDCT scanner. All studies were independently evaluated by 3 blinded neuroradiologists. The Wilcoxon test was applied for the statistical analysis. RESULTS: ACT and MDCT images were of equal diagnostic quality in most cases related to the supratentorial ventricular system and the detection of hemorrhages (subarachnoidal, intraparenchymal, and intraventricular). Regarding the supratentorial ventricular system, an adequate diagnostic quality was assigned to 94% of the ACT acquisitions. For the detection of hemorrhage, no statistically significant difference was noted between ACT and MDCT. However, for the infratentorial region, ACT performed relatively poorly compared with MDCT. The diagnostic evaluation of gray matter (basal ganglia, insular cortex, and central cortex) by ACT is not sufficient, with <20% of the acquisitions scoring a diagnostic value. CONCLUSIONS: After neuroendovascular procedures and within the angiography suite, ACT enables an immediate detection of peri-interventional hemorrhage or hydrocephalus. However, for the detection of cerebral infarction, ACT is not yet reliable.

High-intensity transient signals during laparoscopic surgery in children.

BACKGROUND: Laparoscopic interventions in children gain increasing popularity. Pneumoperitoneum as applied during laparoscopic surgery can induce gas emboli formation, but it is unclear whether this is associated with cerebral embolic events. To investigate the hypothesis that pneumoperitoneum causes cerebral emboli in children, the number and intensity of high-intensity transient signals (HITS) detected using transcranial Doppler ultrasonography were assessed before and after induction of pneumoperitoneum. METHODS: Twenty children were monitored during laparoscopic surgery. General anaesthesia was performed using sevoflurane and sufentanil or alfentanil. Pressure-controlled ventilation was adapted to maintain end-tidal Pco(2) (Pe'(co(2))) between 4.7 and 6.0 kPa. Baseline measurement of HITS rate, cerebral blood flow velocity, and mean arterial pressure (MAP) were recorded during steady-state anaesthesia before skin incision and during pneumoperitoneum with intra-abdominal pressure of 1.6-2.0 kPa applied using CO(2). RESULTS: In 14 children (70%), HITS were detected during baseline and pneumoperitoneum. Three additional children (15%) developed HITS during pneumoperitoneum only and another three children (15%) presented no HITS during the investigation period. MAP and cerebral blood flow velocity increased with pneumoperitoneum. CONCLUSIONS: HITS are present in 70% of paediatric surgical patients under balanced anaesthesia before surgical interventions. Pneumoperitoneum further increased the occurrence of HITS.