Neonatal blood culture inoculant volume: feasibility and challenges.

BACKGROUND: Clinicians often express concerns about poor sensitivity of blood cultures in neonates resulting from inadequate inoculant volumes. Our objective was to determine the inoculant volume sent for neonatal sepsis evaluations and identify areas of improvement. METHODS: Single-center prospective observational study of infants undergoing sepsis evaluation. Blood volume was determined by clinician documentation over 21 months, and additionally by weighing culture bottles during 12 months. Adequate volume was defined as ≥1 mL total inoculant per evaluation. For first-time evaluations, local guidelines recommend sending an aerobic-anaerobic pair with 1 mL inoculant in each. RESULTS: There were 987 evaluations in 788 infants. Clinicians reported ≥1 mL total inoculant in 96.9% evaluations. Among 544 evaluations where bottles were weighed, 93.4% had ≥1 mL total inoculant. Very low birth weight infants undergoing evaluations >7 days after birth had the highest proportion of inadequate inoculants (14.4%). Only 3/544 evaluations and 26/1011 bottles had total inoculant <0.5 mL. Ninety evaluations had <1 mL in both aerobic and anaerobic bottles despite a total inoculant volume that allowed inoculation of ≥1 mL in one of the bottles. CONCLUSIONS: Obtaining recommended inoculant volumes is feasible in majority of neonates. Measuring inoculant volumes can focus improvement efforts and improve test reliability. IMPACT: Clinicians express concern about the unreliability of neonatal blood cultures because of inadequate inoculant volume. We investigated over 900 evaluations and found >90% of evaluations have ≥1 mL inoculant. Monitoring adequacy of blood culture technique can identify areas of improvement and may allay concerns about blood culture reliability. Current recommendations for adequate inoculant volume for blood cultures are met in a majority of neonates. Areas of improvement include preterm late-onset sepsis evaluations and distribution techniques during inoculation.

The impact of daily bladder filling on small bowel dose for intensity modulated radiation therapy for cervical cancer.

Research demonstrates that instructing patients to have a full bladder for pelvic radiotherapy results in highly variable bladder volumes at daily treatment. We aimed to determine bladder volume variation in patients with intact cervical cancer treated with intensity-modulated radiotherapy (IMRT) on an empty bladder and estimate the difference in radiation dose to the small bowel compared to treating on a full bladder. We identified 29 patients treated with IMRT from 2010 to 2013 who underwent 2 planning computed tomography (CT) scans, 1 with a full bladder followed by 1 with an empty bladder. Interfractional variation in bladder volume was measured using 782 daily cone beam computed tomography (CBCT) scans. To estimate dose to small bowel, radiation plans were created on both empty and full bladder CT scans using an automated knowledge-based planning modeling program. Mean bladder volume with empty bladder instructions was 67 ± 26 cc compared to 91 ± 43 cc for no bladder instructions and 154 ± 54 cc for full bladder instructions (p < 0.001). There was a significant reduction in the absolute bladder volume variation in patients given empty bladder instructions compared to full bladder instructions (p < 0.05) The intraclass correlation coefficient showed low reliability of bladder filling across all groups (p = 0.6). The average bowel V45 for the empty bladder plans was 188 cc, compared to 139 cc for the full bladder plans (p < 0.05). More plans created on an empty bladder exceeded Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) guidelines but this was not significant (31% vs 14%, p = 0.12). Reliability of bladder volume at the time of radiation treatment is low, regardless of bladder filling instructions, although an empty bladder reduces absolute variation in bladder volume. Radiation planning on an empty bladder predicts a larger volume of small bowel receiving 45 Gy compared to a full bladder, although bowel dose on average is still within QUANTEC guidelines (V45 < 195 cc).