Estimation of extravascular lung water using the transpulmonary ultrasound dilution (TPUD) method: a validation study in neonatal lambs.

Increased extravascular lung water (EVLW) may contribute to respiratory failure in neonates. Accurate measurement of EVLW in these patients is limited due to the lack of bedside methods. The aim of this pilot study was to investigate the reliability of the transpulmonary ultrasound dilution (TPUD) technique as a possible method for estimating EVLW in a neonatal animal model. Pulmonary edema was induced in 11 lambs by repeated surfactant lavages. In between the lavages, EVLW indexed by bodyweight was estimated by TPUD (EVLWItpud) and transpulmonary dye dilution (EVLWItpdd) (n = 22). Final EVLWItpud measurements were also compared with EVLWI estimations by gold standard post mortem gravimetry (EVLWIgrav) (n = 6). EVLWI was also measured in two additional lambs without pulmonary edema. Bland-Altman plots showed a mean bias between EVLWItpud and EVLWItpdd of -3.4 mL/kg (LOA ± 25.8 mL/kg) and between EVLWItpud and EVLWIgrav of 1.7 mL/kg (LOA ± 8.3 mL/kg). The percentage errors were 109 and 43 % respectively. The correlation between changes in EVLW measured by TPUD and TPDD was r2 = 0.22. Agreement between EVLWI measurements by TPUD and TPDD was low. Trending ability to detect changes between these two methods in EVLWI was questionable. The accuracy of EVLWItpud was good compared to the gold standard gravimetric method but the TPUD lacked precision in its current prototype. Based on these limited data, we believe that TPUD has potential for future use to estimate EVLW after adaptation of the algorithm. Larger studies are needed to support our findings.

Transpulmonary thermodilution cardiac output measurement is not affected by severe pulmonary oedema: a newborn animal study.

BACKGROUND: The transpulmonary thermodilution (TPTD) technique is widely used in clinical practice for measuring cardiac output (CO). This study was designed to investigate the influence of various levels of pulmonary oedema on the reliability of CO measurements by the TPTD method. METHODS: In 11 newborn lambs pulmonary oedema was induced using a surfactant washout technique. Serial CO measurements using TPTD (CO(TPTD)) were performed at various amounts of lung water. Simultaneously, CO was measured by an ultrasound flow probe around the main pulmonary artery (CO(MPA)) and used as the standard reference. CO was divided by the body surface area to calculate cardiac index (CI). Data were analysed using correlational statistics and Bland-Altman analysis. RESULTS: One lamb died prematurely. A total of 56 measurements in 10 lambs were analysed with a median CI(MPA) of 2.95 (IQR 1.04) litre min(-1) m(-2). Mean percentage increase in extravascular lung water (EVLW) between the start and the end of the study was 126.4% (SD 40.4). Comparison of the two CO methods showed a mean bias CI of -0.16 litre min(-1) m(-2) (limits of agreement ±0.73 litre min(-1) m(-2)) and a percentage error of 23.8%. Intraclass correlation coefficients were 0.91 (95% CI 0.81-0.95) for absolute agreement and 0.92 (95% CI 0.87-0.95) for consistency. Acceptable agreement was confirmed by a tolerability-agreement ratio of 0.39. The within-subject correlation between the amount of EVLWI and the bias between the two methods was not significant (-0.02; P=0.91). CONCLUSIONS: CO measurements by the transpulmonary thermodilution technique over a wide range of CI values are not affected by the presence of high EVLWI. The slight underestimation of the CO is independent of the amount of pulmonary oedema.

Cardiac output measurement with transpulmonary ultrasound dilution is feasible in the presence of a left-to-right shunt: a validation study in lambs.

BACKGROUND: Cardiac output (CO) monitoring remains complex in newborns as most of the current technologies fail to accurately measure systemic blood flow in the presence of shunts. We validated CO measurements using transpulmonary ultrasound dilution (TPUD) in a neonatal lamb model with a left-to-right shunt. METHODS: Regular arterial and central venous catheters were inserted into seven lambs (3.5-8.3 kg). A surgically constructed left-to-right aorto-pulmonary Gore-Tex(®) shunt was intermittently opened and closed, while CO was manipulated by creating haemorrhagic hypotension. CO measurements with TPUD (COtpud) were compared with those obtained by an ultrasonic transit-time flow probe positioned around the main pulmonary artery (COufp). RESULTS: We performed 72 sessions of three paired CO measurements. The mean COufp was 1.00 litre min(-1) (range 0.47-1.75 litre min(-1)) and mean COtpud 1.05 litre min(-1) (range 0.54-1.87 litre min(-1)). With an open shunt, the mean Qp/Qs ratio was 1.8 (range 1.3-2.6). A comparison between COufp and COtpud showed a mean bias (sd) of 0.03 (0.09) and 0.07 (0.10) litre min(-1), respectively, for measurements with a closed and an open shunt. The percentage error was 18% and 20% for measurements with a closed and an open shunt. Polar plot analysis showed good trending ability for both closed and open shunt groups. CONCLUSIONS: TPUD is a reliable technology to measure CO in the presence of a left-to-right shunt.

Influence of lung injury on cardiac output measurement using transpulmonary ultrasound dilution: a validation study in neonatal lambs.

BACKGROUND: Transpulmonary ultrasound dilution (TPUD) is a promising method for cardiac output (CO) measurement in severely ill neonates. The incidence of lung injury in this population is high, which might influence CO measurement using TPUD because of altered lung perfusion. We evaluated the influence of lung injury on the accuracy and precision of CO measurement using TPUD in an animal model. METHODS: In nine neonatal lambs, central venous and arterial catheters were inserted and connected to the TPUD monitor. Repeated lavages with warmed isotonic saline were performed to gradually induce lung injury. CO measurements with TPUD (COtpud) were compared with those obtained by an ultrasonic transit-time flow probe around the main pulmonary artery (COufp). An increase in oxygenation index was used as an indicator of induced lung injury during the experiment. Post-mortem lung injury was confirmed by histopathological examination. RESULTS: Fifty-five sessions of three paired CO measurements were analysed. The mean COufp was 1.53 litre min(-1) (range 0.66-2.35 litre min(-1)), and the mean COtpud was 1.65 litre min(-1) (range 0.78-2.91 litre min(-1)). The mean bias (standard deviation) between the two methods was 0.13 (0.15) litre min(-1) with limits of agreement of ±0.29 litre min(-1). The overall percentage error was 19.1%. The accuracy and precision did not change significantly during progressive lung injury. Histopathological severity scores were consistent with heterogeneous lung injury. The capability to track changes in CO using TPUD was moderate to good. CONCLUSIONS: The accuracy and precision of CO measurement using TPUD is not influenced in the presence of heterogeneous lung injury in an animal model.

Feasibility Study of Vascular Access and REBOA Placement in Quick Response Team Firefighters.

BACKGROUND: Early hemorrhage control using resuscitative endovascular balloon occlusion of the aorta (REBOA) can save lives. This study was designed to evaluate the ability to train Quick Response Team Fire Fighters (QRT-FF) to gain percutaneous femoral artery access and place a REBOA catheter in a model, using a comprehensive theoretical and practical training program. METHODS: Six QRT-FF participated in the training. SOF medics from a previous training served as the control group. A formalized training curriculum included basic anatomy and endovascular materials for percutaneous access and REBOA placement. Key skills included (1) preparation of an endovascular toolkit, (2) achieving vascular access in the model, and (3) placement and positioning of REBOA. RESULTS: QRT-FF had significantly better scores compared with medics using endovascular materials (P = .003) and performing the procedure without unnecessary attempts (P = .032). Basic surgical anatomy scores for QRT-FF were significantly better than SOF medics (P = .048). QRT-FF subjects demonstrated a significantly higher overall technical skills point score than medics (P = .030). QRT-FF had a median total time from start of the procedure to REBOA inflation of 3:23 minutes, and medics, 5:05 minutes. All six QRT-FF subjects improved their procedure times-as did four of the five medics. CONCLUSIONS: Our training program using a task training model can be utilized for percutaneous femoral access and REBOA placement training of QRT-FF without prior ultrasound or endovascular experience. Training the use of advanced bleeding control options such as REBOA, as a secondary occupational task, has the potential to improve outcomes for severely bleeding casualties in the field.

[Neonatal subgaleal haemorrhage; a potential life-threatening extracranial haemorrhage]. / De subgaleale bloeding bij de neonatus; een potentieel levensbedreigende extracraniële bloeding.

A female neonate delivered at term developed hypovolemic shock due to a subgaleal haemorrhage, i.e. extracranial bleeding between the galea aponeurotica and the cranial periosteum. The subgaleal haemorrhage was most likely the result of a traumatic vacuum extraction. The patient was treated with large volumes of fluids and blood products and received additional circulatory and respiratory support. The clinical features of neonatal subgaleal haemorrhage are different from other, more common causes of head swelling in neonates. Subgaleal haemorrhage is characterised by a progressive, diffuse, mobile, elastic swelling that is not confined by the sutures. In contrast, cephalic haematoma is a fixed, elastic swelling that is confined by the sutures. Caput succedaneum is a soft, poorly defined swelling that is immediately visible post partum. Traumatic vacuum extraction clearly increases the risk of developing subgaleal haemorrhage. Given the high mortality associated with subgaleal haemorrhage, we emphasise the importance of early diagnosis and adequate treatment of this disorder. Subgaleal haemorrhage carries an increased risk of having other concurrent disorders, such as intracranial haemorrhage. Therefore, further cerebral imaging should be considered in patients with subgaleal haemorrhage.

[The first newborn with congenital rubella syndrome during the rubella epidemic in The Netherlands in 2004/'05]. / De eerste pasgeborene met congenitaal rubellasyndroom tijdens de rubella-epidemie in Nederland in 2004/'05.

A newborn male was diagnosed with congenital rubella syndrome. His 31-year-old mother had had erythematous exanthema during a period of amenorrhea lasting 7 weeks; she was not vaccinated and had never had a rubella infection. The infection was confirmed serologically. The mother gave birth to an icteric, microcephalic, dysmature neonate with hepatosplenomegaly and exanthema with multiple, small purple-red spots. Ultrasound cardiography revealed a persistently open arterial duct and a small defect of the ventricular septum. Radiological evaluation of the long bones showed the characteristic longitudinal lucent strands ('celery stalk appearance'). Ultrasound of the cerebrum showed diffuse widespread calcifications in the white matter and basal ganglia, striatal vasculopathy and diffuse parenchymal disorders. Psychomotor development was impaired. The patient was completely deaf in the left ear and had severely poor hearing in the right ear. After the introduction of the rubella vaccine in the Netherlands in 1974 a substantial decrease was seen in the incidence of rubella infections as well as congenital rubella syndrome. An epidemic of rubella infections has been present within the non-vaccinated population since September 2004. Recognition of the clinical symptoms and confirmation of the clinical suspicion with proper viral diagnostic methods are needed to control the current epidemic and to prevent secundary spread. Infants born with congenital rubella syndrome remain infectious to non-vaccinated individuals for a prolonged period of time; the virus is excreted in the urine and faeces. Long-term medical follow-up is necessary because the congenital rubella infection can cause abnormalities after the neonatal period.