Standard Intravenous Catheter Research Articles

Peripheral Intravenous Waveform Analysis Responsiveness to Subclinical Hemorrhage in a Rat Model.

Early detection and quantification of perioperative hemorrhage remains challenging. Peripheral intravenous waveform analysis (PIVA) is a novel method that uses a standard intravenous catheter to detect interval hemorrhage. We hypothesize that subclinical blood loss of 2% of the estimated blood volume (EBV) in a rat model of hemorrhage is associated with significant changes in PIVA. Secondarily, we will compare PIVA association with volume loss to other static, invasive, and dynamic markers. Eleven male Sprague Dawley rats were anesthetized and mechanically ventilated. A total of 20% of the EBV was removed over ten 5 minute-intervals. The peripheral intravenous pressure waveform was continuously transduced via a 22-G angiocatheter in the saphenous vein and analyzed using MATLAB. Mean arterial pressure (MAP) and central venous pressure (CVP) were continuously monitored. Cardiac output (CO), right ventricular diameter (RVd), and left ventricular end-diastolic area (LVEDA) were evaluated via transthoracic echocardiogram using the short axis left ventricular view. Dynamic markers such as pulse pressure variation (PPV) were calculated from the arterial waveform. The primary outcome was change in the first fundamental frequency (F1) of the venous waveform, which was assessed using analysis of variance (ANOVA). Mean F1 at each blood loss interval was compared to the mean at the subsequent interval. Additionally, the strength of the association between blood loss and F1 and each other marker was quantified using the marginal R2 in a linear mixed-effects model. PIVA derived mean F1 decreased significantly after hemorrhage of only 2% of the EBV, from 0.17 to 0.11 mm Hg, P = .001, 95% confidence interval (CI) of difference in means 0.02 to 0.10, and decreased significantly from the prior hemorrhage interval at 4%, 6%, 8%, 10%, and 12%. Log F1 demonstrated a marginal R2 value of 0.57 (95% CI 0.40-0.73), followed by PPV 0.41 (0.28-0.56) and CO 0.39 (0.26-0.58). MAP, LVEDA, and systolic pressure variation displayed R2 values of 0.31, and the remaining predictors had R2 values ≤0.2. The difference in log F1 R2 was not significant when compared to PPV 0.16 (95% CI -0.07 to 0.38), CO 0.18 (-0.06 to 0.04), or MAP 0.25 (-0.01 to 0.49) but was significant for the remaining markers. The mean F1 amplitude of PIVA was significantly associated with subclinical blood loss and most strongly associated with blood volume among the markers considered. This study demonstrates feasibility of a minimally invasive, low-cost method for monitoring perioperative blood loss.

Long peripheral catheters and midline catheters: Insights from a survey of vascular access specialists.

Peripheral intravenous access is no longer limited to the standard intravenous catheter (cannula). Devices varying in length, material and insertion technique, are increasingly accessible. There is substantial variability surrounding the nomenclature and use of these devices in the literature. We wished to understand the attitude of vascular access specialists towards the nomenclature and use of peripheral intravenous catheters (PIVCs), long peripheral catheters (LPCs) and midline catheters (MCs). A 15-question electronic survey was sent to members of the Association of Vascular Access (AVA) regarding the nomenclature and use of PIVCs, LPCs and MCs. A total of 228 participants completed the survey. Approximately two-thirds of respondents use LPCs (65.8%) and MCs (71.9%) in their clinical practice. The most common indication for LPCs was difficult venous access (56.5%), while the most common indication for MCs was medium-term (1-4 weeks) intravenous therapy (62.7%). The majority of participants (57.9%) agreed with the following classification of peripheral intravenous devices:PIVCs: 2 to 6 cm in length, terminating distal to the axilla;LPCs: 6 to 15 cm in length, terminating distal to the axilla;MCs: 15-25 cm in length, terminating in the axilla.Participants suggested that the length of the catheter should be considered a general recommendation, as LPCs and MCs should be primarily differentiated by tip location. The majority of vascular access specialists from AVA have incorporated LPCs and MCs into their repertoire of peripheral venous access tools. We envisage that their use will increase as the clinical community becomes more familiar with these devices.

An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo.

The detection and analysis of rare blood biomarkers is necessary for early diagnosis of cancer and to facilitate the development of tailored therapies. However, current methods for the isolation of circulating tumour cells (CTCs) or nucleic acids present in a standard clinical sample of only 5-10 ml of blood provide inadequate yields for early cancer detection and comprehensive molecular profiling. Here, we report the development of a flexible magnetic wire that can retrieve rare biomarkers from the subject's blood in vivo at a much higher yield. The wire is inserted and removed through a standard intravenous catheter and captures biomarkers that have been previously labelled with injected magnetic particles. In a proof-of-concept experiment in a live porcine model, we demonstrate the in vivo labelling and single-pass capture of viable model CTCs in less than 10 s. The wire achieves capture efficiencies that correspond to enrichments of 10-80 times the amount of CTCs in a 5-ml blood draw, and 500-5,000 times the enrichments achieved using the commercially available Gilupi CellCollector.

Improved technique for rodent microarteriography.

We have developed new techniques in rodent microarteriography which provide excellent two-plane views of the rat femoral artery. These techniques employ routine mammography film and equipment for imaging as well as standard intravenous catheters for vascular access. The use of mammographic equipment provides high quality, finely detailed, orthogonal X-ray images. The elective outpatient nature of mammography allows microsurgical investigators convenient access to the necessary equipment without interfering with patient care. The standard intravenous catheters permit easy and inexpensive vascular access via the contralateral femoral artery. The technique avoids the more invasive thoracic and abdominal aortic approaches without compromising X-ray image quality. Additionally, the same rat can be imaged multiple times if care is taken to repair the vascular access route.

18 POST-HEMORRHAGIC HYDROCEPHALUS: NINE YEAR EXPERIENCE WITH THE USE OF AN INTRAVENOUS CATHETER FOR EXTERNAL VENTRICULAR DRAINAGE OF CSF

Post-hemorrhagic hydrocephalus (PHH) is an acute sequel to large IVH in preterm infants. We have used standard criteria for the diagnosis and treatment of PHH over the past nine years. PHH is defined as an increase in head circumference of >2cm/week with a confirming cranial ultrasound scan. Treatment consists of external ventricular drainage (EVD) using a standard intravenous catheter placed in the lateral ventricle through the anterior fontanelle and attached to a closed drainage system. EVD is attempted for 7 days, then removed. Recurrence of PHH is followed by repeated episodes of EVD until resolution or the infant reaches 2Kg mass, at which point a ventriculoperitoneal (VP) shunt is placed. 24 infants with PHH were seen over the period. During 70 episodes of EVD in this group only a single infection occurred. All episodes of EVD were associated with a decrease in ventricular size and head circumference. Of 21 infants who survived, 9 were discharged without a VP shunt. This method of treatment of PHH is safe and compares favorably with other methods of avoiding VP shunt.

Radial artery cannulation guided by Doppler ultrasound

A technique to enhance difficult percutaneous radial artery cannulations using Doppler ultrasound is described. A series of 12 patients (nine hypotensive and three normotensive patients with poorly palpable or absent radial pulses) was assembled and the radial arteries were cannulated using standard intravenous catheters and a hand-held Doppler ultrasound device. Localization and cannulation of the arteries was facilitated by noting the characteristic sounds using the Doppler. Eleven of the 12 patients had successful cannulation of the radial artery. In one case the artery was localized but the catheter could not be advanced. No complications were encountered. It was concluded that the use of a common Doppler ultrasound on selected patients with poor peripheral pulses may facilitate percutaneous radial artery cannulations and minimize the number of catheter punctures before successful placement.