Mammary blood flow regulation in the nursing rabbit

Sprint interval training in the postpartum period maintains the enhanced cardiac output of pregnancy: A case study

During pregnancy an increased cardiac output (Q ̇ $\dot{Q}$ ) and blood volume (BV) occur to support fetal growth. IncreasedQ ̇ $\dot{Q}$ and BV also occur during chronic endurance exercise training and benefit performance. We investigated if sprint interval training (SIT) undertaken early postpartum maintains the elevatedQ ̇ $\dot{Q}$ and BV of pregnancy and benefits performance. The participant, a competitive field hockey player and former cyclist, visited our laboratory at 2 weeks of gestation (baseline) and postpartum pre-, mid- and post-intervention (PPpre, PPmid and PPpost). Delivery was uncomplicated and she felt ready to start the SIT programme 5 weeks postpartum. Inert gas rebreathing was used to measure peak exerciseQ ̇ $\dot{Q}$ (Q ̇ $\dot{Q}$ peak);V ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ was measured with a metabolic cart; and postpartum haematological values were measured with carbon monoxide rebreathing. The 18 SIT sessions progressed from four to eight sprints at 130% ofV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ peak power output.Q ̇ $\dot{Q}$ peak increased from baseline at all postpartum time points (baseline 16.2 vs. 17.5, 16.8 and 17.2 L/min at PPpre, PPmid and PPpost, respectively). RelativeV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ remained below baseline values at all postpartum measurements (baseline 44.9 vs. 41.0, 42.3 and 42.5 mL/kg/min at PPpre, PPmid and PPpost, respectively) whereas absoluteV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ rapidly reached baseline values postpartum (baseline 3.19 vs. 3.12, 3.23 and 3.18 L/min at PPpre, PPmid and PPpost, respectively). Postpartum BV (5257, 4271 and 5214 mL at PPpre, PPmid and PPpost, respectively) and Hbmass (654, 525 and 641 g at PPpre, PPmid and PPpost, respectively) were similar between PPpre and PPpost but decreased alongsideQ ̇ $\dot{Q}$ peak at PPmid. Peak power was returned to pre-pregnancy values by intervention end (302 vs. 303 W, baseline vs. PPpost). These findings show that SIT undertaken early postpartum defends the elevatedQ ̇ $\dot{Q}$ peak of pregnancy and rapidly returns absoluteV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ and peak power to baseline levels.

Blood flow characteristics of the human lactating breast

BACKGROUND

Despite the increased metabolic activity of the lactating breast, no studies have been carried out to determine mammary blood flow (MBF) parameters or the relationship between MBF and milk production in women. The aim of this study was to measure the MBF in the internal mammary artery (IMA) and lateral thoracic artery (LTA) of lactating women and determine if these were related to milk production.

METHODS

Blood flow in the IMA and LTA was measured with color Doppler ultrasound in 55 lactating women. Twenty-four-hour milk production was determined with the test-weigh method.

RESULTS

IMA contributed the greater proportion of blood flow to the lactating breast (70%). MBF was highly variable between women but consistent between the left (126 L/24 h; interquartile range, 76-169) and right (110 L/24 h) breasts. No relationship between MBF and milk production was demonstrated. For 3 women, MBF was markedly reduced in 1 breast that was synthesizing almost no milk compared to the other that was producing a normal volume of milk.

DISCUSSION

Although no relationship between MBF and milk production was found, the substantial reduction in blood flow in the breasts of lactating women producing almost no milk suggests a threshold below which milk production is compromised.

CONCLUSION

Doppler ultrasound did not demonstrate a relationship between MBF and milk production in lactating women. Further investigation is required to fully understand the role of blood flow in milk synthesis.

Changes in breast skin temperature during the course of breastfeeding

Breast skin temperature was measured during breastfeeding in 11 mothers on a total of 47 occasions, using a Coretemp CM-210 (Terumo Corp, Tokyo, Japan), to examine the changes of breast skin temperature during the course of breastfeeding. In both breasts, the breast skin temperature was significantly higher than the baseline skin temperature from the beginning of suckling up to 5 minutes after completion of suckling, and the mean breast skin temperature before breastfeeding between 4 days and 8 weeks postpartum was significantly higher than that on the first 1 to 2 days postpartum. These results show that the breast skin temperature increases between the first 1 to 2 days and 4 to 5 days postpartum and that breast skin temperature remains high during suckling and up to 5 minutes after the completion of suckling. These findings will be useful for educating mothers during the perinatal period on the normal course of breastfeeding by individual instruction or in classes.

Teaching the virtues: justifications and recommendations

The current interest in and discussion of virtue ethics suggests that this approach to moral decisionmaking has several distinct advantages as applied to ethical issues in healthcare delivery. For the most part, calls to incorporate the virtues of the healthcare provider in discussions of these issues have sought to supplement rather than totally replace traditional ethical theories, such as the utilitarian focus on maximizing the best overall consequences and the Kantian concern to act on the duty of respect for persons. Including virtue-based ethics in such discussions allows for a more eclectic view of what should be considered in resolving difficult moral problems. As many critics of the purely principle-based approach have noted, real moral dilemmas are usually quite messy and are not easily susceptible to satisfactory resolution solely on the basis of abstract moral theories or principles.