Skin blood flow changes during apneic spells in preterm infants

Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneously in each infant. During 212 apneic spells with a duration of 11.6 ± 7.5 s (mean ± S.D.) (range 6.0–48.0 s), the laser Doppler skin blood flow was measured. In all children except one, the majority of the apneic spells was associated with a decrease in skin blood flow. During 155 apneic spells (73%) skin blood flow decreased significantly P < 0.025), the maximum decrease being 16.7 ± 14.8%, 28.5 ± 23.9% and 18.9 ± 16.1% (mean ± S.D.) for central, obstructive and mixed apneic spells, respectively. The decrease in skin blood flow started immediately after the beginning of apneic spells in 71%, the rest started with a mean delay of 3.4 s (range 0.1–7.0 s). No relation was found between the decrease in skin blood flow and the duration of the apneic spells. Thirty-four percent of the apneic spells were accompanied by bradycardia. In apneic spells accompanied by bradycardia the decrease in skin blood flow was not related to the fall in heart rate

Incidence and duration of total occlusion of the radial artery in newborn infants after catheter removal

The incidence and duration of total occlusion of the radial artery after catheter removal was determined using repeated Doppler flow measurements. Thirty-two newborn infants with birthweights ranging from 945 g to 3890 g (median 1935 g) and gestational age ranging from 26 to 40 weeks (median 32 weeks) were studied. In 20 out of 32 infants (63%), complete occlusion of the radial artery occurred. The number of occlusions were not related to birthweight, gestational age or duration of cannulation. In all infants, blood flow in the radial artery resumed within 1-29 days after catheter removal. The duration of occlusion was directly related to the duration of cannulation and inversely related to birthweight. This study demonstrates a high frequency of total occlusion of the radial artery in newborn infants after percutaneous radial artery cannulation. In the majority of infants with a radial artert catheter, blood flow to the tissue distal to the cannulation site is dependent solely on the existence of an adequate arterial palmar collateral circulation

Assessment of joystick and wrist control in hand-held articulated laparoscopic prototypes

Various steerable instruments with flexible distal tip have been developed for laparoscopic surgery. The problem of steering such instruments, however, remains a challenge, because no study investigated which control method is the most suitable. This study was designed to examine whether thumb (joystick) or wrist control method is designated for prototypes of steerable instruments by means of motion analysis. Methods: Five experts and 12 novices participated. Each participant performed a needle-driving task in three directions with two prototypes (wrist and thumb) and a conventional instrument. Novices performed the tasks in three sessions, whereas experts performed one session only. The order of performing the tasks was determined by Latin squares design. Assessment of performance was done by means of five motion analysis parameters, a newly developed matrix for assigning penalty points, and a questionnaire. Results: The thumb-controlled prototype outperformed the wrist-controlled prototype. Comparison of the results obtained in each task showed that regarding penalty points, the up ? down task was the most difficult to perform. Conclusions: The thumb control is more suitable for steerable instruments than the wrist control. To avoid uncontrolled movements and difficulties with applying forces to the tissue while keeping the tip of the instrument at the constant angle, adding a ‘‘locking’’ feature is necessary. It is advisable not to perform the needle driving task in the up down directionBiomechanical EngineeringMechanical, Maritime and Materials Engineerin

Milieu en energie effecten van warmtepompen en HR ketels.Deelrapport van de literatuurstudie Milieu effecten van Energiebesparing (MIEN 4) (115p.)

Toepassing van warmtepompen in de verwarmingssector is aantrekkelijk. Een gasmotorwarmtepomp levert meer energiebesparing op dan hoog rendementsketels (HR-ketels) of elektrische warmtepompen. De NOx-Emissie bij gasmotoren zal echter verder moeten worden beperkt. Dit om te voorkomen dat door toepassing van grote aantallen gasmotorwarmtepompen de totale NOx-Uitworp in Nederland stijgt. De overige negatieve milieu-effecten (geluidshinder, emissie van freon en motorolie) zijn relatief eenvoudig beheersbaar. Absorptiewarmtepompen bieden ten opzichte van andere systemen belangrijke milieuvoordelen: geringe emissie van NOx geen emissie van freon of motorolie en geen geluidshinder. Als opvolger van de HR-ketel lijkt de absorptiewarmtepomp bijzonder geschikt. De verdere ontwikkeling en introductie absorptiewarmtepompen dient te worden gestimuleerd. De energiebesparing kan hierdoor oplopen tot 5% van het huidige nationale energieverbruik, terwijl bovendien de totale stikststofoxidenemissie iets afneemt.

Development of low birthweight infants at 19 months of age correlates with early intake and status of long-chain polyunsaturated fatty acids

We investigated the influence of early nutrition with and without long-chain polyunsaturated fatty acids (LCP) on later development of less than or equal to 2500 g newborns receiving preterm formula without LCP (n=75), preterm formula with 18:3 omega 6 and LCP omega 3 (at two doses; n=26) or their mother's own milk (n=27). All diets were given from birth to day 42. Erythrocytes (RBC) fatty-acid compositions were determined on day 42. Bayley's mental development (MDI) and psychomotor development (PDI) indices were assessed at 19 months. Multivariate regression analysis revealed that PDI was most strongly related to RBC 22:6 omega 3 in the cohort of 101 infants who received formula. The most consistent correlations were between development and early LCP omega 3 intake, and between development and parameters of RBC LCP omega 3 status day 42, in infants who received formula with 18:3 omega 6 and LCP omega 3. Development of formula-fed low-birthweight infants seems positively influenced by early dietary LCP omega 3. (C) 1999 Harcourt Publishers Ltd