Is Continuous Flow Superior to Pulsatile Flow in Single Ventricle Mechanical Support? Results from a Large Animal Pilot Study.

Durable mechanical support in situations of physiologic single ventricle has been met with little success so far, particularly in small children. We created an animal model to investigate whether pulsatile or continuous flow would be superior. Three 1 month old sheep (10-16 kg) were instrumented. Via sternotomy and with cardiopulmonary bypass, a large ventricular septal defect and atrial septal defect were created. The left ventricle was cannulated using a Berlin Heart inflow cannula. This was connected sequentially to a continuous flow device (Thoratec HeartMate X, Pleasanton, CA) and to a pulsatile device (Berlin Heart Excor, The Woodlands, TX). Outflow was via a Y-graft to both aorta and pulmonary artery, striving for equal flow to both. Atrial filling pressures were controlled with volume infusions over a wide range. Under comparable loading conditions, significantly higher maximum flow was obtained by HeartMate X than by Excor (4.95 ± 1.27 L/min [range, 3.84-6.34 L/min] for HeartMate X vs. 1.80 ± 0.85 L/min [range, 1.01-2.7 L/min] for Excor; p < 0.05). Judging from this limited animal study, in single ventricle scenarios, continuous flow devices may achieve higher pump flows than pulsatile devices when provided with similar filling pressures. Their clinical use should be investigated. More extensive experimental studies are needed.

Effectiveness of 1% diclofenac gel in the treatment of wrist extensor tenosynovitis in long distance kayakers.

Anecdotally many athletes use non-steroidal anti-inflammatory gels during competition to allow continued participation. To determine if this clinical practice is useful a randomised placebo-controlled study was conducted at the 5-day 2004 Red Cross Murray River Marathon. Forty-two kayakers presented with wrist extensor tenosynovitis while competing in the single and double kayak events. All subjects received standard treatment of ice, stretches and massage for wrist tenosynovitis before being randomised into a placebo or 1% diclofenac gel group. Evaluation was done by using a visual analogue scale (0-10) for pain and by clinical grading (0-3). The main outcome measurements were reduction in pain and clinical grading, the requirement for a rescue medication (paracetamol or diclofenac tablets) and effect on performance times. Both groups had similar pain scores and clinical grading on the first and fifth days of pain. On the second to fourth days of pain there was clearly no benefit and possibly a detrimental effect on pain with diclofenac gel relative to placebo. However, diclofenac tablets were possibly beneficial for pain relative to paracetamol tablets. The effects of pain and the various treatments on performance time were either trivial (<0.5%) or small, but none was particularly clear. We conclude that standard treatment appears to be sufficient for the management of wrist extensor tenosynovitis during competition.

Continuous insulin infusion in hyperglycaemic extremely-low- birth-weight neonates.

BACKGROUND: The inability of the newborn to inhibit gluconeogenesis in response to a glucose infusion leading to insulin resistance has been postulated as an important cause of hyperglycaemia observed in premature infants. AIM: The aim of this study was to determine the efficiency and rate of response to continuous insulin infusion in improving glucose tolerance in hyperglycaemic extremely-low-birth-weight (ELBW) neonates (< or =1,000 g) compared to neonates with birth weight >1,000 g (LBW). METHODS: We included in the study 115 consecutive neonates in the neonatal intensive care unit who developed hyperglycaemia from January 2000 to December 2001. A standard protocol for the use of exogenous insulin infusions was commenced for all hyperglycaemic neonates. The efficiency of continuous insulin infusion was compared in two groups of infants: ELBW < or =1,000 g compared with neonates with birth weight >1,000 g (LBW). RESULTS: The duration (hours) of insulin infusion required to normalise blood glucose level was significantly longer in the ELBW group compared to LBW group (p < 0.0001). Average insulin infusion (units/kg/h) required to maintain normoglycaemia was also significantly higher in the ELBW group (p < 0.0001). No significant difference was found in the mean amount of intravenous dextrose tolerated, mean postnatal age (hours) at which infusions were initiated and the average blood glucose recorded. ELBW infants were more likely to receive steroid administration, have surgery, higher CRIB scores and sepsis. CONCLUSION: Continuous insulin infusion was relatively safe and effective in the treatment of persistent hyperglycaemia in premature neonates. No serious adverse side effects of insulin therapy were noted. With the current protocol for use of exogenous insulin infusion at our unit, the response to treatment was significantly slower in the ELBW neonates. The dose of insulin infusion required to maintain normoglycaemia was also higher in this group of neonates. There may be a need for different treatment schedules for this subgroup of neonates so that normalisation of blood glucose can be achieved earlier.

Assessment of three methods of pH probe positioning in preterm infants.

BACKGROUND: In the assessment of gastroesophageal reflux, correct placement of the pH catheter is crucial. This is particularly so in very low birth weight infants where a small error in positioning could give rise to a potentially large error in results. Accepted modes of assessing correct positioning can be problematic in this population of infants and alternative methods were investigated. METHODS: A total of 26 preterm infants (<35 weeks gestation) were enrolled in this study. All infants were suspected of having GOR and pH monitoring was performed. Probe position was assessed using Strobel's formula, manometry and acid-alkali interface and confirmed by chest x-ray. RESULTS: There was a highly significant positive correlation between the calculation of the pH probe position using Strobel's formula and the position on x-ray and a significant positive correlation between the acid/alkali interface and x-ray position. There was no correlation between manometry and x-ray position and this method was also shown to be problematic in its' application. CONCLUSION: The data suggests that it is appropriate to use Strobel's formula as a method of accurate positioning of pH probes in preterm infants, thus avoiding the need for additional x-rays. The acid/alkali interface, when obtainable, is a secondary, satisfactory method to confirm the position calculated by Strobel's formula.

Attitudes of anesthesiologists about addiction and its treatment: a survey of Illinois and Wisconsin members of the American Society of Anesthesiologists.

STUDY OBJECTIVE: To survey practicing anesthesiologists about their attitudes about addiction and its treatment by means of a previously validated instrument. DESIGN: Anonymous mail survey. SETTING: Metropolitan medical college. PARTICIPANTS: Active members of the American Society of Anesthesiologists in Illinois and Wisconsin. MAIN RESULTS: The survey consisted of 50 statements presented in a five item Likert (agreement-disagreement) format that evaluated five attitude factors: permissiveness, nonstereotypes, treatment interventions, treatment optimism, and nonmoralism. Five hundred twelve completed and 21 undeliverable surveys were returned from 1,656 surveys mailed (response rate = 31%). The raw scores for the five attitude factors were permissiveness 25 +/- 6, nonstereotypes 34 +/- 6, treatment interventions 32 +/- 4, treatment optimism 19 +/- 3, and nonmoralism 31 +/- 5 (means +/- SD). Anesthesiologists with a personal history of addiction recorded attitude scores that were significantly (p < 0.05) higher than those of their colleagues. Formal training in substance abuse management, attendance at a Twelve Step meeting as either a participant or an observer, and experience with a friend, relative, or colleague with addiction were also associated with significantly higher attitude scores. The attitude scores of anesthesiologists were consistently below those previously reported for clinicians who regularly care for patients with addiction. CONCLUSIONS: Personal experience with, or education about, addiction contributes to a more positive attitude about addiction. Anesthesiologists have less positive attitudes about addiction than do physicians who regularly manage the disease.