Howard Harris

Effect of open-heart surgery on the body composition of infants and young children.

Summary: Body water content and distribution were determined in 16 children aged 2 wk to 28 months before and after open-heart surgery for correction of congenital cardiac defects. Operative procedures were performed using hypothermia and extracorporeal oxygenation. On the day before and the day after surgery, total body water was estimated as the antipyrine space (APS); extracellular water, as the corrected bromide space (CBS), and plasma volume, as the 10-min T-1824-albumin space. Intracellular water (ICW) was assumed to be the difference between APS and CBS; interstitial water was calculated from plasma volume and CBS. Before initiation and after completion of extracorporeal circulation, a pectoral muscle biopsy was performed, and a blood sample was obtained. Muscle total water (TW) content was determined by desiccation, extracellular water (ECW) was estimated as the corrected chloride space, and ICW was assumed to be the difference between TW and ECW. Plasma sodium, potassium, chloride, glucose, and osmolality contents were determined by routine methods. All studies were not completed in all patients.Although APS and CBS increased in eight of 11 children, mean APS (± S.E.) before and after surgery (662 ± 28.0 versus 714 ± 37.2 ml/kg) and mean CBS (335 ± 30.5 versus 358 ± 15.5 ml/kg) were not statistically different. Mean ICW changed neither in relation to body weight (328 ± 28.0 versus 355 ± 34.2 ml/kg) nor in relation to APS (ICW/APS ratio = 0.48 ± 0.040 versus 0.49 ± 0.010). Neither mean PV (54 ± 4.0 versus 56 ± 2.8 ml/kg) nor mean blood volume (92 ± 5.4 versus 90 ± 5.5 ml/kg) changed significantly. Mean interstitial water increased by 9 to 68% over preoperative values in all but one patient (238 ± 10.4 versus 305 ± 13.4 ml/kg; P < 0.01).Muscle composition was not affected by the procedure. Mean TW was 79 ± 1.3 ml/100 g before extracorporeal circulation and 78 ± 0.8 ml/100 g afterwards whereas ECW averaged 32 ± 4.4 and 36 ± 3.4 ml/100 g, and ICW averaged 48 ± 4.6 and 42 ± 2.9 ml/100 g. Mean ICW/TW ratios were 0.60 ± 0.055 and 0.54 ± 0.040 ml/100 g.Although mean plasma sodium (142 ± 3.5 versus 139 ± 2.4 mEq/liter) and potassium (3.3 ± 0.16 versus 3.6 ± 0.15 mEq/liter) concentrations did not change appreciably during extracorporeal circulation; mean plasma chloride content decreased (108 ± 2.9 versus 100 ± 2.0 mEq/liter; P < .002). Plasma glucose averaged 60 mg/dl more at completion of the procedure, increasing from a mean of 223 ± 25.6 mg/dl to a mean of 283 ± 5.3 mg/dl (P < 0.05). Plasma osmolality increased in five of eight children, but mean osmolalities were similar before and after extracorporeal circulation (301 ± 8.9 versus 303 ± 5.4 mOsm/kg).These data suggest that a childs organism does not react complacently to the invasive procedures associated with open-heart surgery. Further research into effects of these procedures and into means of minimizing undesirable homeostatic disturbances is warranted.Speculation: Body composition of adult patients has been shown to be acutely altered by open-heart surgery with hypothermia and extracorporeal circulation. Our data suggest that similar changes occur in young children who are subjected to these procedures. Because small children, especially those afflicted with major congenital defects, have limited homeostatic capabilities, the risk of these disturbances becoming life-threatening is increased. Means of minimizing them need be devised.

Nasal Continuous Positive Airway Pressure

Continuous positive airway pressure (CPAP) was employed using nasal prongs in 30 neonates with hyaline membrane disease (HMD). There was a significant improvement in mean Pa02 (from 47 to 80 mmHg; p

NASAL END-EXPIRATORY PRESSURE |[lpar]|NEEP|[rpar]| IN THE MANAGEMENT OF HYALINE MEMBRANE DISEASE |[lpar]|HMD|[rpar]|

End-expiratory pressure utilizing nasal prongs was used in 43 babies, 30 with clinical HMD, during a 7 month period. In the HMD group, [xmacr ] birth weight was 2020g(8<1500g) and [xmacr ] gestation was 33½ wks. PaO2 was <60mmHg in ≥ 60%fiO2 in all HMD prior to NEEP. Treatment was begun at [xmacr ] 23½ hrs. after birth and [xmacr ] duration of treatment was 43 hrs. Pressures employed ranged from 6-15cmH2O, the mouth not taped shut, and gastric decompression was routine. Within [xmacr ] 36 minutes of treatment, [xmacr ] PaO2 nearly doubled in stable fiO2([xmacr ] PaO2 47 ± 17.5 before and 80±36.2 after; [xmacr ] fiO2 72% before and 73% after). PaCO2, and pH were unchanged. In 18 in whom NEEP was begun within 24 hrs. of birth, [xmacr ] ΔPaO2 of 116% was significantly higher than the 35% of those 12 treated later(p < .025). The ΔPaO2 exceeded 50% in 12/18 early treated and in only 3/12 late treated (p< .01). Prognosis was not predicted by initial PaO2 response: [xmacr ] ΔPaO2 was 79% in survivors and 96% in those who died. Of the 25 survivors, only 1 required further ventilatory support, while in none of the dying babies was NEEP failure corrected by subsequent endotracheal CPAP and/or mechanical ventilation. FiO2 of [xmacr ] 73% was decreased to <60% in [xmacr ] 15 hrs. (range ½-86). In 13 babies with other causes for respiratory difficulty, NEEP failed to significantly affect PaO2 ([xmacr ] 49 before; 69 after). These data suggest that NEEP is a simple, non-invasive, effective technique in the management of HMD. Our only complication has been pneumothorax, occuring in 3 infants who survived.