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Altered respiratory rate is one of the first symptoms of medical conditions that require timely intervention, e.g., sepsis or opioid-induced respiratory depression. To facilitate continuous respiratory rate monitoring on general hospital wards a contactless, non-invasive, prototype monitor was developed using frequency modulated continuous wave radar. We aimed to study whether radar can reliably measure respiratory rate in postoperative patients. In a diagnostic cross-sectional study patients were monitored with the radar and the reference monitor (pneumotachograph during mechanical ventilation and capnography during spontaneous breathing). Eight patients were included; yielding 796 min of observation time during mechanical ventilation and 521 min during spontaneous breathing. After elimination of movement artifacts the bias and 95 % limits of agreement for mechanical ventilation and spontaneous breathing were −0.12 (−1.76 to 1.51) and −0.59 (−5.82 to 4.63) breaths per minute respectively. The radar was able to accurately measure respiratory rate in mechanically ventilated patients, but the accuracy decreased during spontaneous breathing. Electronic supplementary material The online version of this article (doi:10.1007/s10877-015-9777-5) contains supplementary material, which is available to authorized users.

Background Generally, only the type of operation is used to estimate the need for perioperative homologous blood transfusion. This study quantified the extent to which the estimation could be improved if, in addition, simple patient characteristics were taken into account. Methods Retrospective data on 24 509 consecutive adult surgical patients were used to derive and validate three models to predict perioperative homologous transfusion. The first model was a univariable model with type of operation as the only predictor. The second and third models were a full and a simplified multivariable logistic regression model. The performance of the multivariable models was tested in two validation sets: in similar patients who had operations in the same general hospital (internal validation) and in patients who had operations in a university hospital (external validation). The areas under the receiver–operator characteristic (ROC) curve were compared with that found in the derivation set. Results There were no important differences in characteristics between the derivation and validation sets. The ROC area of the model including surgery only was 0·92 (99 per cent confidence interval (c.i.) 0·91 to 0·94) and that of the full and simplified multivariable models 0·95 (99 per cent c.i. 0·94 to 0·96) and 0·94 (99 per cent c.i. 0·93 to 0·95) respectively. The latter two were significantly different from the first one. In the external validation set the ROC area of the simplified model was 0·84 (95 per cent c.i. 0·83 to 0·86). Patients who had a preoperative haemoglobin level lower than 13 g/dl and underwent major invasive surgery had the highest risk (43 per cent) of transfusion. Conclusion A simple algorithm using type of operation and haemoglobin concentration was effective in identifying patients likely to need perioperative homologous blood transfusion.

Background Propofol, a short-acting hypnotic drug, is increasingly administered by a diverse group of specialists (e.g., cardiologists, gastroenterologists) during diagnostic and therapeutic procedures. Standard monitoring during sedation comprises continuous pulse oximetry with visual assessment of the patient's breathing pattern. Because undetected hypoventilation is a common pathway for complications, capnographic monitoring of exhaled carbon dioxide has been advocated. We examined whether the use of capnography reduces the incidence of hypoxemia during nonanesthesiologist-administered propofol sedation in patients who did not receive supplemental oxygen routinely. Methods An open, stratified, randomized controlled trial was conducted in 427 healthy adult women during minor gynecology procedures in an outpatient clinic in the Netherlands. Patients were randomly assigned to receive either standard respiratory monitoring (standard care) or standard respiratory monitoring combined with capnography (capnography group). To replicate usual clinical practice, capnography monitoring was performed by the same medical team that provided sedation. The primary end point was the incidence of hypoxemia, defined as oxygen saturations Results From April 2010 to January 2011, 427 patients were enrolled. In the capnography group, 206 patients and in the standard care group, 209 patients were analyzed. The percentage of patients with a hypoxemic episode was 25.7% (53 of 206) in the capnography group and 24.9% (52 of 209) in the standard care group, resulting in an absolute difference of 0.8% (-7.5 to 9.2%). Conclusions We were unable to confirm an additive role for capnography in preventing hypoxemia during elective nonanesthesiologist-administered propofol (monotherapy) sedation in healthy women in whom supplemental oxygen is not routinely administered. Based on the confidence interval, the benefit of adding capnography is at most an absolute hypoxemia reduction of 7.5%, suggesting that adding it in this practice setting to the routine monitoring strategy does not necessarily improve patient safety in daily practice.

Study Objective: To determine the effect of a new signal processing technique (Oxismart ™ , Nellcor, Inc., Pleasanton, CA) on the incidence of false pulse oximeter alarms in the operating room (OR). Design: Prospective observational study. Setting: Nonuniversity hospital. Patients: 53 ASA physical status I, II, and III consecutive patients undergoing general anesthesia with tracheal intubation. Measurements and Main Results: In the OR we compared the number of alarms produced by a recently developed third generation pulse oximeter (Nellcor Symphony ™ N-3000) with Oxismart ™ signal processing technique and a conventional pulse oximeter (Criticare ™ 504). Three pulse oximeters were used simultaneously in each patient: a Nellcor pulse oximeter, a Criticare with the signal averaging time set at 3 seconds (Criticare average3s ) and a similar unit with the signal averaging time set at 21 seconds (Criticare average21s ). For each pulse oximeter, the number of false (artifact) alarms was counted. One false alarm was produced by the Nellcor (duration 55 sec) and one false alarm by the Criticare average21s monitor (5 sec). The incidence of false alarms was higher in Criticare average3s . In eight patients, Criticare average3s produced 20 false alarms (p ). Conclusions: Our study did not show a beneficial effect in the OR on the incidence of false alarms of the Nellcor monitor with Oxismart ™ signal processing compared with the Criticare monitor with the longer averaging time of 21 seconds.

Study Objective: To determine the effect of a new pulse oximeter (Nellcor Symphony™ N-3000, Pleasanton, CA) with signal processing technique (Oxismart™) on the incidence of false alarms in the postanesthesia care unit (PACU). Design: Prospective study. Setting: Nonuniversity hospital. Patients: 603 consecutive ASA physical status I, II, and III patients recovering from general or regional anesthesia in the PACU. Interventions: We compared the number of alarms produced by a recently developed "third"-generation pulse oximeter (Nellcor Symphony™ N-3000) with Oxismart™ signal processing technique and a conventional pulse oximeter (Criticare™ 504, Waukesha, WI). Patients were randomly assigned to either a Nellcor pulse oximeter or a Criticare with the signal averaging time set at either 12 or 21 seconds. For each patient the number of false (artifact) alarms was counted. Measurements and Main Results: The Nellcor generated one false alarm in 199 patients and 36 (in 31 patients) "loss of pulse" alarms. The conventional pulse oximeter with the averaging time set at 12 seconds generated a total of 32 false alarms in 17 of 197 patients [compared with the Nellcor, relative risk (RR) 0.06, confidence interval (CI) 0.01 to 0.25] and a total of 172 "loss of pulse" alarms in 79 patients (RR 0.39, CI 0.28 to 0.55). The conventional pulse oximeter with the averaging time set at 21 seconds generated 12 false alarms in 11 of 207 patients (compared with the Nellcor, RR 0.09, CI 0.02 to 0.48) and a total of 204 "loss of pulse" alarms in 81 patients (RR 0.40, CI 0.28 to 0.56). The lower incidence of false alarms of the conventional pulse oximeter with the longest averaging time compared with the shorter averaging time did not reach statistical significance (false alarms RR 0.62, CI 0.3 to 1.27; "loss of pulse" alarms RR 0.98, CI 0.77 to 1.3). Conclusions: To date, this is the first report of a pulse oximeter that produced almost no false alarms in the PACU.

In a prospective, randomized study, we have investigated the effects of two arbitrary pulse oximeter lower alarm limit (LAL) settings (90% = group 90, n = 320 and 85% = group 85, n = 327) on the incidence of hypoxaemia in the recovery room. In group 90, we calculated the theoretical effect of elimination of transient episodes of low pulse oximeter oxyhaemoglobin saturation (SpO2) by introducing a time delay between the onset of the alarm condition and triggering of the alarm. When only hypoxaemic episodes lasting more than 1 min were included, SpO2 < or = 90% occurred in 11% of patients in group 90 and in 20% in group 85 (relative risk (RR) 1.84, confidence interval (CI) 1.26-2.69; P < 0.01). Hypoxaemia < or = 85% occurred in 2% of patients in group 90 and in 6% in group 85 (RR 3.10, CI 1.32-7.28; P < 0.01). In group 90, 1007 alarms (33% false) occurred, whereas in group 85, 395 alarms (28% false) occurred. Introducing a theoretical delay of 15 s in group 90 between crossing the alarm threshold and triggering the alarm would have reduced the number of alarms by 60%. The results of the study suggest that decreasing the alarm limit in an attempt to reduce frequent false alarms may lead to an increase in more relevant episodes of hypoxaemia and setting the LAL at 85% cannot be recommended routinely. Introducing a 15 s delay in group 90 would reduce the number of alarms by the same amount as changing the LAL from 90% to 85%.

In dit rapport wordt een overzicht gegeven van de oxidant (NO2 + O2) - concentraties in Nederland gedurende de perioden 10 t/m 18 juni 1989, 24 t/m 27 juni 1989, 3 t/m 9 juli 1989, 19 t/m 21 augustus 1989 en 5 t/m 9 september 1989. Op landelijk gelegen stations lagen de daggemiddelde oxidantconcentraties op de dagen met de hoogste niveaus rond de 80 a 85 ppb. In sterk door verkeer beinvloede situaties lagen de daggemiddelde oxidantconcentraties circa 10 ppb hoger. De hoogste oxidantconcentratie werd gemeten op 7 september 1989 te Naaldwijk. De daggemiddelde oxidantconcentratie bedroeg hier 108 ppb. Gedurende 34 uren werden uurgemiddelde ozonwaarden groter dan 240 mug/m3 gemeten. Door het RIVM werden gedurende de beschreven perioden de provinciale milieudiensten en de inspectie geinformeerd op basis van zowel de meetgegevens van het LML als de tijdens de episode uitgevoerde prognostische modelberekeningen. Door een aantal provincies werd op basis van de smogalarmregeling een aantal keren de waarschuwingsfase uitgeroepen.

In dit rapport wordt een atmosferisch transportmodel beschreven dat de verspreiding van en depositie op Europese schaal van een willekeurige stof beschrijft. Het model is een afgeleide versie van het RIVM mesoschaal puff-model. Uitgaande van een standaard-emissie worden de concentraties (uurgemiddelde) en de deposities (daggemiddelde) van een stof berekend. De meteo-invoer is afkomstig van het LAM-model van het KNMI (3 uurlijkse velden: 1000-850 mbar wind ; regen). De concentratievelden en positievelden worden voor hetzelfde gebied weggeschreven waarvoor ook de meteovelden geldig zijn. Dit gebied ligt niet vast en kan aan de hand van de aard en de plaats van de calamiteit gekozen worden. Verdere ontwikkeling van het model zal in samenwerking met het KNMI plaatsvinden. Het kan hierbij zowel om een radioactief als om een chemisch verontreinigende stof gaan.

In dit rapport wordt een overzicht gegeven van de oxidant (NO-2 + O-3)- concentraties in Nederland tijdens deze episode. Op landelijk gelegen stations werden daggemiddelde waarden van meer dan 80 ppb gevonden. In sterk door verkeer beinvloede situaties werden waarden boven 90 ppb bereikt. Op een groot aantal stations werden uurgemiddelde ozonwaarden groter dan 200 mug/m gemeten. Door het RIVM werden gedurende de gehele periode de provinciale milieudiensten en de inspectie geinformeerd op basis van zowel de meetgegevens van het LML als de tijdens de episode uitgevoerde prognostische modelberekeningen. Door een aantal provincies werd op basis van de smogalarmregeling de waarschuwingsfase uitgeroepen.

Na een periode van strenge vorst in de eerste helft van januari 1987 is een weersituatie ontstaan waarbij in centraal en West-Europa hoge niveaus van luchtverontreiniging zijn opgetreden. Door aanvoer vanuit brongebieden in Oost-Europa worden in de periode van 14-22 januari in geheel Nederland zwaveldioxide concentraties gemeten in de orde van 300 u,g/m3 in het zuid-oosten van het land worden de concentraties extra verhoogd door aanvoer vanuit het Roergebied. Door het RIVM zijn gedurende de gehele episode de provinciale milieudiensten en de inspecties geinformeerd op basis van zowel de meetgegevens van het landelijk meetnet en de additionele uitgevoerde meetwagenmetingen als de tijdens de episode uitgevoerde prognostische modelberekeningen. In Limburg wordt gedurende het optreden van hoge NO2-niveaus de alarmfase afgekondigd. Mede aan de han van de modelberekeningen wordt in dit rapport een meet gedetailleerd overzicht

Ground-level ozone and oxidant (sum of O3 and NO2) concentrations in The Netherlands are calculated during the growing season (May–September) by means of a Lagrangian long-range transport model. Two air parcels—one representative of the mixed layer, the other representative of the polluted layer above the mixed layer (aged smog layer)—are followed along 96 h back trajectories. Long-term averaged and 98 percentile values of hourly averaged concentrations are estimated on the basis of concentrations calculated for four arrival times per day for all days in the period considered. In a number of sensitivity runs the influence of European anthropogenic NOx and VOC emissions on the oxidant concentrations in The Netherlands has been investigated. In general, the influence of European emissions on the 98-percentile values is 2–3 times as large as on the averaged concentrations. This indicates that long-term averaged concentrations more strongly depend on the concentrations in the free troposphere whereas the episodic concentrations are determined by photochemical production over Europe. VOC emission reduction is more effective in lowering episodic concentrations than NOx emission reduction. For long-term averaged concentrations, however, NOx and VOC emission reduction of 50% or more are nearly equally effective.

In both 2006 and 2007 a large operating room fire occurred in the Netherlands. One patient died as a result of a sudden intense flash fire caused by a leaking oxygen connection. Smaller operating room fires can cause severe burn injuries and inhalation trauma in patients. An oxygen-enriched atmosphere is an important causative factor in most surgical fires. Inflammable substances and ignition sources, such as a diathermic knife or laser, may be present in the operating theatre and environs. The combination of these 3 components (fuel, oxygen and ignition) increases the risk of operation room fires. Prevention and control of this hazard depends on removal of one or more of the 3 components.

Seasonal averaged ground level concentrations for O3 have been calculated for The Netherlands by means of a two-layer Lagrangian long-range transport (LRT) model. The model includes emissions, nonlinear atmospheric chemistry, dry deposition, exchange between boundary layer (BL) and free troposphere (FT) and fumigation between a mixed layer and an aged smog layer. Concentrations of primary and secondary pollutants in the FT are obtained from a two-dimensional global model developed by Isaksen. In the reference calculation the modelled concentrations of Ox (sum of O3 and NO2) and O3 are in fair agreement with measurements. The NOx (sum of NO and NO2) and NO2 concentrations are under-estimated by the model but there is a good temporal correlation between calculated and measured concentrations. Validation of other components involved in the chemical scheme is hardly possible due to the paucity of measured data. It can only be stated that the results presented in this paper are not in disagreement with measured or modelled data presented in the literature. In a number of sensitivity runs the influence of European anthropogenic emissions of NOx and volatile organic compounds (VOC) has been investigated. The calculations indicate that the influence of European emissions on the growing season, daytime averaged (May–September, 10–17 h) O3 concentrations in The Netherlands is small. For European reductions in the order of tens of per cents a VOC emission reduction is more effective than a NOx emission reduction in lowering the O3 concentrations. For strong reductions (about 70%) VOC and NOx are equally effective. The effects of the modelled underprediction of NOx concentrations on the production of O3 on a European scale are probably small. On a local scale the effects are more pronounced due to the NO/O3 titration (photostationary equilibrium). Therefore, an empirical correction is applied on the modelled O3 concentrations. After this correction, it is shown that daytime O3 levels during the growing season increase when European NOx emissions are reduced (2.0–7.7.% increase at 50% NOx emission reduction). A reduction in VOC emission leads to decreasing O3 levels (9% reduction for 40% VOC emission reduction, 16% reduction for 70% VOC emission reduction). For a combined reduction of both VOC and NOx slightly decreasing ground level O3 concentrations are expected.

A 37-y-old male was admitted to the ICU because of meningitis and respiratory failure with epileptic seizures. Spinal fluid grew Streptococcus salivarius. Prior to presentation the patient underwent surgical excision of a chronic toe ulcer, performed under spinal anaesthesia, which raised the suspicion of iatrogenic origin of the disease. The clinical situation deteriorated over the following d and the patient died from multi-organ failure. Careful hygiene measures are needed to prevent such a severe complication.

A 37-year-old man in a status epilepticus due to meningitis was admitted to Intensive Care because of respiratory insufficiency. Spinal fluid culture yielded Streptococcus salivarius. Despite extensive diagnostics, the source of this bacterium could not be found. However, the patient had recently undergone spinal anaesthesia for surgery on a toe ulcer, from which other bacteria were cultured. The patient died 2 weeks after admission with a picture of multiple organ failure. Bacterial meningitis following spinal anaesthesia may be the result of impairment of the blood-brain barrier due to a sudden drop of spinal fluid pressure during the puncture, or of the introduction of bacteria from the hair follicles or from a haematoma caused by the needle or the introducer. Hygienic measures and a proper technique when performing regional anaesthesia are important in preventing the dissemination of bacteria.

In many patients, a 'type and screen' procedure is routinely performed before surgery. However, most patients are not transfused after all. Can we predict, which surgical patients will and will not be transfused, to reduce the number of these investigations? We studied 1482 consecutive surgical patients with intermediate risk for transfusion. Multivariate logistic regression modelling and the area under the Receiver Operating Characteristic curve (ROC area) were used to quantify how well age, gender, surgical procedure, emergency or elective surgery and anaesthetic technique predicted transfusion, and whether the preoperative haemoglobin concentration had added predictive value. Gender, age > or =70 yr, and type of surgery were independent predictors of transfusion, with a ROC area of 0.75 (95% CI: 0.72-0.79). Validating this model with an easily used prediction rule in a second patient population yielded a ROC area of 0.70 (95% CI: 0.63-0.77). With this rule type and screen could correctly be withheld in 35% of these patients. In the remaining 65% of the patients, a further reduction in type and screen investigations of 15% could be achieved using the preoperative haemoglobin concentration. Using a simple prediction rule, preoperative type and screen investigations in patients who have to undergo surgery procedures with intermediate transfusion risk can be avoided in about 50%. This may reduce patient burden and hospital costs (on average: 3 million US$ per 100 000 procedures).

The potential benefit of a reduced frequency of false pulse oximeter low oxyhemoglobin saturation (SpO2) alarms is that the attention of personnel is only directed to patients who experience hypoxemia. The present study was undertaken to better understand the effects of different settings of the pulse oximeter on false (artifact) and true (hypoxemia) alarms.Using the original SpO2 data of 200 postoperative patients, we calculated off-line the effects of five methods (artifact rejection, alarm delay (2-44 s, 2 s increments), averaging (10-90 s), median filtering (10-90 s) and decreasing the alarm limit from 90% to 85%) on the number of (true- and false) alarms.830 episodes of hypoxemia (SpO2or = 90%) and 73 episodes of severe hypoxemia (SpO2or = 85%) occurred. With a SpO2 alarm limit of 90%, the alarm was triggered 1535 times (830 true, 705 false). Artifact rejection reduced alarms by almost 50%. An alarm delay of 6 s or an averaging or median filtering epoch of 10 s resulted in an alarm reduction of almost 50%. No differences were found in the reduction of alarms between averaging and median filtering. Changing the alarm limit to 85% reduced the number of alarms by 82%. A similar reduction of alarms was obtained with either an alarm delay of 18 s or an averaging or median filtering epoch of 42 s. However, an alarm limit of 85% reduced the number of false alarms less than the other three algorithms (p0.01).The data from the present study suggest that in order to effectively suppress false alarms caused by pulse oximeter artifacts, it may be preferable to use a longer filtering epoch of approximately 40 s, rather than to decrease the lower alarm limit.

We have studied the influence of motivation of care providers on the incidence and duration of postoperative hypoxaemia in the recovery room. In a prospective, switch-back designed cohort study, we have compared the incidence of low pulse oximeter saturation values (SpO2) during pre-intervention, intervention and post-intervention phases. Low SpO2 values were classified as either hypoxaemia (SpO2or = 90%, minimum duration 1 min) or artefact. Pulse oximetry trend data from 1350 patients, 450 in each group, were analysed. During the intervention phase, motivation was increased by adding an explicit instruction to prevent and treat low SpO2 values and making personnel aware that they were being studied (Hawthorne effect). The incidence of hypoxaemia decreased significantly from 17.8% during the pre-intervention phase to 11.6% during the intervention phase (relative risk (RR) 0.65, 95% confidence interval (CI) 0.47-0.90; P0.01). The incidence of severe hypoxaemia (SpO2or = 85%, 1 min) decreased from 7.8% to 3.3% (RR 0.43, CI 0.24-0.76; P0.01). The number of patients who had severe hypoxaemia for more than 5 min decreased from 13 to 1 (RR 0.08, CI 0.02-0.36; P0.01). In the post-intervention period, the incidence of hypoxaemia returned to pre-intervention values. The results of this study suggest that motivation of care providers to prevent and treat low SpO2 is an important determinant of postoperative hypoxaemia in the recovery room.