Prediction of postoperative patient deterioration and unanticipated intensive care unit admission using perioperative factors

BACKGROUND AND OBJECTIVES: Currently, no evidence-based criteria exist for decision making in the post anesthesia care unit (PACU). This could be valuable for the allocation of postoperative patients to the appropriate level of care and beneficial for patient outcomes such as unanticipated intensive care unit (ICU) admissions. The aim is to assess whether the inclusion of intra- and postoperative factors improves the prediction of postoperative patient deterioration and unanticipated ICU admissions. METHODS: A retrospective observational cohort study was performed between January 2013 and December 2017 in a tertiary Dutch hospital. All patients undergoing surgery in the study period were selected. Cardiothoracic surgeries, obstetric surgeries, catheterization lab procedures, electroconvulsive therapy, day care procedures, intravenous line interventions and patients under the age of 18 years were excluded. The primary outcome was unanticipated ICU admission. RESULTS: An unanticipated ICU admission complicated the recovery of 223 (0.9%) patients. These patients had higher hospital mortality rates (13.9% versus 0.2%, p&lt;0.001). Multivariable analysis resulted in predictors of unanticipated ICU admissions consisting of age, body mass index, general anesthesia in combination with epidural anesthesia, preoperative score, diabetes, administration of vasopressors, erythrocytes, duration of surgery and post anesthesia care unit stay, and vital parameters such as heart rate and oxygen saturation. The receiver operating characteristic curve of this model resulted in an area under the curve of 0.86 (95% CI 0.83-0.88). CONCLUSIONS: The prediction of unanticipated ICU admissions from electronic medical record data improved when the intra- and early postoperative factors were combined with preoperative patient factors. This emphasizes the need for clinical decision support tools in post anesthesia care units with regard to postoperative patient allocation.</p

The impact of the catheter to vein ratio on peripheral intravenous cannulation success, a post-hoc analyses

BACKGROUND: Intravenous cannulation is usually the first procedure performed in modern healthcare, although establishing peripheral intravenous access is challenging in some patients. The impact of the ratio between venous diameter and the size of the inserted catheter (catheter to vein ratio, CVR) on the first attempt success rate can be of added value in clinical. This study tries to give insight into the consideration that must be made when selecting the target vein and the type of catheter, and proved the null hypothesis that an optimal CVR would not be associated with increased first attempt cannulation success. METHODS: This was a post-hoc analyses on adult patients admitted for peripheral intravenous cannulation. Intravenous cannulation was performed according to practice guidelines, by applying the traditional landmark approach. The CVR was calculated afterwards for each individual patient by dividing the external diameter of the inserted catheter by the diameter of the target vein, which was multiplied by 100%. RESULTS: In total, 610 patients were included. The median CVR was 0.39 (0.15) in patients with a successful first attempt, whereas patients with an unsuccessful first attempt had a median CVR of 0.55 (0.20) (P0.41 had a first attempt success rate of 65% (P<0.001). CONCLUSION: This first introduction of the CVR in relation to cannulation success should be further investigated. Although, measuring the venous diameter or detection of a vein with a specific diameter prior to cannulation may increase first attempt cannulation success

Differences in ultrasound elevational beam width (slice thickness) between popular handheld devices

Background: Handheld ultrasound devices are increasingly used by medical professionals for bedside ultrasound-guided interventions. Especially for vascular access procedures, the width of the imaging plane, known as the slice thickness or elevational beam width is a prominent source for misinterpretation. A wide slice thickness can lead to the interpretation that 2 objects (i.e. needle and vessel) are on the same plane while in fact they are not and thereby negatively influencing the performance of in-plane ultrasound-guided interventions. Therefore, the beam profiles of three popular handheld US devices are tested and compared to a conventional US device. Methods: The GE VScan, Philips Lumify and Butterfly IQ ​+ ​are tested using a slice phantom to determine the slice thickness. For comparison, a Philips Affiniti machine was investigated. Both linear and curved array settings were analyzed. In a slice phantom, a diffuse scattering plane at an angle of exactly 45° is scanned. For each imaging depth, the vertical height of the imaged rectangle corresponds to the slice thickness at that depth. Main results: For the linear array transducers, the focus depth ranges from 1.5 to 3.5 cm. At the focus depth, all transducers have a reasonable slice thickness of approximately 1 mm. More superficially, the slice thickness varies between 1 and 4 mm. The curved array probes have larger focus depths, ranging from 2.7 to 7.3 cm. The slice thickness at focus depth varies between 1.4 and 3.8 mm, but at 2 cm depth is even more than 5 mm. Conclusions: The slice thickness of handheld ultrasound transducers varies between the different devices, and can be suboptimal for superficial in-plane ultrasound-guided interventions. The larger slice thickness of the curved array settings may complicate in-plane guidance. Handheld ultrasound users should be aware of the beam characteristics of their devices to optimize guidance for interventions

The learning curve for ultrasound-guided peripheral intravenous cannulation in adults: a multicenter study

AIMS: To lower the threshold for applying ultrasound (US) guidance during peripheral intravenous cannulation, nurses need to be trained and gain experience in using this technique. The primary outcome was to quantify the number of procedures novices require to perform before competency in US-guided peripheral intravenous cannulation was achieved. MATERIALS AND METHODS: A multicenter prospective observational study, divided into two phases after a theoretical training session: a hands-on training session and a supervised life-case training session. The number of US-guided peripheral intravenous cannulations a participant needed to perform in the life-case setting to become competent was the outcome of interest. Cusum analysis was used to determine the learning curve of each individual participant. RESULTS: Forty-nine practitioners participated and performed 1855 procedures. First attempt cannulation success was 73% during the first procedure, but increased to 98% on the fortieth attempt (p<0.001). The overall first attempt success rate during this study was 93%. The cusum learning curve for each practitioner showed that a mean number of 34 procedures was required to achieve competency. Time needed to perform a procedure successfully decreased when more experience was achieved by the practitioner, from 14±3 minutes on first proce-dure to 3±1 minutes during the fortieth procedure (p<0.001). CONCLUSIONS: Competency in US-guided peripheral intravenous cannulation can be gained after following a fixed educational curriculum, resulting in an increased first attempt cannulation success as the number of performed procedures increased

Robust and semantic needle detection in 3D ultrasound using orthogonal-plane convolutional neural networks

Purpose: During needle interventions, successful automated detection of the needle immediately after insertion is necessary to allow the physician identify and correct any misalignment of the needle and the target at early stages, which reduces needle passes and improves health outcomes. Methods: We present a novel approach to localize partially inserted needles in 3D ultrasound volume with high precision using convolutional neural networks. We propose two methods based on patch classification and semantic segmentation of the needle from orthogonal 2D cross-sections extracted from the volume. For patch classification, each voxel is classified from locally extracted raw data of three orthogonal planes centered on it. We propose a bootstrap resampling approach to enhance the training in our highly imbalanced data. For semantic segmentation, parts of a needle are detected in cross-sections perpendicular to the lateral and elevational axes. We propose to exploit the structural information in the data with a novel thick-slice processing approach for efficient modeling of the context. Results: Our introduced methods successfully detect 17 and 22 G needles with a single trained network, showing a robust generalized approach. Extensive ex-vivo evaluations on datasets of chicken breast and porcine leg show 80 and 84% F1-scores, respectively. Furthermore, very short needles are detected with tip localization errors of less than 0.7 mm for lengths of only 5 and 10 mm at 0.2 and 0.36 mm voxel sizes, respectively. Conclusion: Our method is able to accurately detect even very short needles, ensuring that the needle and its tip are maximally visible in the visualized plane during the entire intervention, thereby eliminating the need for advanced bi-manual coordination of the needle and transducer

Clinical use of electrical stimulation with the Veinplicity® device and its effect on the first attempt success rate of peripheral intravenous cannulation: A non-randomized clinical trial

BACKGROUND: Peripheral intravenous cannulation is one of the most frequently performed medical procedures. Venodilation, which can be achieved with different techniques, is an important factor for first attempt success. The objective of this study was to compare the first attempt success rates upon peripheral intravenous cannulation after applying a tourniquet, with venous dilation by electrical stimulation using the Veinplicity® device, or a combination of both techniques, in participants at moderate risk of a difficult peripheral intravenous access. METHODS: This non-randomized clinical trial was carried out in adult patients divided into three parallel study groups, consisting of cannulation with a tourniquet (control group), cannulation after electrical stimulation without using a tourniquet (intervention group 1), and cannulation after applying electrical stimulation followed by the application of a tourniquet on the selected upper extremity (intervention group 2). The primary outcome was the first attempt success rate of peripheral intravenous catheter placement. RESULTS: In all, 141 participants were included in this study, with an overall success rate of 86%. Success rates of 78%, 88%, and 92% were observed in the control group, intervention group 1, and intervention group 2, respectively (p = 0.25, χ2 = 2.771, df = 2). A higher first attempt success rate was detected in participants in intervention group 2, when compared to the control group (p = 0.04, χ2 = 4.63, df = 1). CONCLUSION: Increase in first attempt success was clinically relevant when electrical stimulation with the Veinplicity® device was combined with the application of a tourniquet in participants at moderate risk of a difficult peripheral intravenous access

Validation of heart rate extracted from wrist-based photoplethysmography in the perioperative setting: Prospective observational study

Background: Measurement of heart rate (HR) through an unobtrusive, wrist-worn optical HR monitor (OHRM) could enable earlier recognition of patient deterioration in low acuity settings and enable timely intervention. Objective: The goal of this study was to assess the agreement between the HR extracted from the OHRM and the gold standard 5-lead electrocardiogram (ECG) connected to a patient monitor during surgery and in the recovery period. Methods: In patients undergoing surgery requiring anesthesia, the HR reported by the patient monitor's ECG module was recorded and stored simultaneously with the photopletysmography (PPG) from the OHRM attached to the patient's wrist. The agreement between the HR reported by the patient's monitor and the HR extracted from the OHRM's PPG signal was assessed using Bland-Altman analysis during the surgical and recovery phase. Results: A total of 271.8 hours of data in 99 patients was recorded simultaneously by the OHRM and patient monitor. The median coverage was 86% (IQR 65%-95%) and did not differ significantly between surgery and recovery (Wilcoxon paired difference test P=.17). Agreement analysis showed the limits of agreement (LoA) of the difference between the OHRM and the ECG HR were within the range of 5 beats per minute (bpm). The mean bias was -0.14 bpm (LoA between -3.08 bpm and 2.79 bpm) and -0.19% (LoA between -5 bpm to 5 bpm) for the PPG- measured HR compared to the ECG-measured HR during surgery; during recovery, it was -0.11 bpm (LoA between -2.79 bpm and 2.59 bpm) and -0.15% (LoA between -3.92% and 3.64%). Conclusions: This study shows that an OHRM equipped with a PPG sensor can measure HR within the ECG reference standard of -5 bpm to 5 bpm or -10% to 10% in the perioperative setting when the PPG signal is of sufficient quality. This implies that an OHRM can be considered clinically acceptable for HR monitoring in low acuity hospitalized patients

On the value of MRI for improved understanding of cuff-based oscillometric measurements

Blood pressure (BP) is a key parameter in critical care and in cardiovascular disease management. BP is typically measured via cuff-based oscillometry. This method is highly inaccurate in hypo- and hypertensive patients. Improvements are difficult to achieve because oscillometry is not yet fully understood; many assumptions and uncertainties exist in models describing the process by which arterial pulsations become expressed within the cuff signal. As a result, it is also difficult to estimate other parameters via the cuff such as arterial stiffness, cardiac output and pulse wave velocity (PWV)-BP calibration. Many research modalities have been employed to study oscillometry (ultrasound, computer simulations, ex-vivo studies, measurement of PWV, mechanical analysis). However, uncertainties remain; additional investigation modalities are needed. In this study, we explore the extent to which MRI can help investigate oscillometric assumptions. Four healthy volunteers underwent a number of MRI scans of the upper arm during cuff inflation. It is found that MRI provides a novel perspective over oscillometry; the artery, surrounding tissue, veins and the cuff can be simultaneously observed along the entire length of the upper arm. Several existing assumptions are challenged: tissue compression is not isotropic, arterial transmural pressure is not uniform along the length of the cuff and propagation of arterial pulsations through tissue is likely impacted by patient-specific characteristics (vasculature position and tissue composition). Clinical Relevance - The cuff interaction with the vasculature is extremely complex; existing models are oversimplified. MRI is a valuable tool for further development of cuff-based physiological measurements