We received 221 responses and excluded 5, as data were incomplete, leaving 216 questionnaires available for analysis. Most survey respondents (83 %) were from specialist or Level III centres, and 41 % were affiliated to University hospitals caring for a combined figure of over 26,000 very low birth weight (VLBW, <1500 g) infants annually. Characteristics of the institutions from which participants responded are presented in Table 1. The response rate was 100 % for Irish, Czech and Belgian centres.
Table 1 Institution demographics of survey participants
Recommendations for diagnosis and treatment of hypotension were established in 61 and 65 % of all centres, respectively. Hypotension was defined as a mean BP in mmHg less than the GA in weeks by 73 % of respondents. Other criteria including predefined percentile or specific limits believed to be associated with poor outcome were used significantly less often (10 and 4 %, respectively); 12 % reported using a combination of these criteria.
Diagnostic methods of poor perfusion
All respondents assessed perfusion clinically (Fig. 1), with measurement of capillary refill time (CRT) on the chest the preferred method (76 %). This was considered pathological if it is more than 3 s by 59 % of respondents. Laboratory methods were used by 75 %, the commonest being both acid base measurement (70 %) and lactate analysis (70 %). Serum biomarkers of myocardial dysfunction—including pro-Brain Natriuretic Peptide, Troponin T and Troponin I—were documented by 28 % of respondents. Ancillary methods of assessment were used by 60 % of participants (Table 2). Of these, the most frequently used was echocardiography (74 %). Table 2 highlights the results of the most commonly reported echo measurements. The predominant measurement performed was left ventricular output (LVO) followed by fractional shortening of left ventricle. Right ventricular output (RVO) or superior vena cava (SVC) flow was used less frequently (34 and 38 %, respectively).
Table 2 Ancillary investigations used to evaluate poor perfusion (180 respondents)
Therapeutic approaches to hypotension
Overall 85 % reported giving a fluid bolus as their first treatment, with the majority (93 %) administering crystalloid. The initial amount administered was 10 ml/kg by 82 % of respondents. The total volume given before using another agent was 20 ml/kg by 59 %, 30 ml/kg by 14 % and >30 ml/kg in 13 % of centres. Dopamine was the most commonly used first-line inotrope (80 %), used alone (62 %) or in combination with dobutamine (18 %). The median starting dose of dopamine was 5 mcg/kg/min, and median maximum dose was 20 mcg/kg/min. If the BP did not increase with the initial inotrope infusion, dobutamine with dopamine was the most popular second-line treatment (28 %). However, there was great variation in the choice of the second agent used (Table 3). Seventy-five percent of respondents altered the therapeutic regime when managing low BP in the presence of a patent ductus arteriosus (PDA) considered to be haemodynamically significant. In this situation, indomethacin or ibuprofen was given by 77 %, with fluid restriction or avoidance of volume administration less often used (46 and 29 %, respectively).
Table 3 Choice of inotrope intervention for hypotension (188 respondents)
Therapeutic regimens
Variables were subjected to the Twostep cluster analysis to identify respondent groups who follow a similar course of treatment. The algorithm identified four different clusters, and the results show that the most prevalent approach to the hypotension therapy in ELGANs was primary volume administration followed by inotrope treatment with dopamine. Responder distribution in the particular clusters was compared with the number of intensive care beds, number of VLBW patients, type of institution, existence of institutional guidelines and the region. None of the above mentioned variables, except the region, were found to have similar cluster representation. Cluster variation in different region is shown in Table 4.
Table 4 Practice variation in different region
Finally, the concept of ‘permissive hypotension’—not intervening when the BP is lower than previously accepted normative values in the absence of any signs of poor perfusion—appears to be an approach that many (80 %) of the respondents stated that they would consider using.