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Respiratory failure.

Abstract

Patients with respiratory failure should be approached in a systematic way, with emphasis both in diagnosis and treatment on arterial blood gases. The intelligent assessment of oxygenation, ventilation and acid-base balance, based on physiologic principles, can make the management of these patients very rewarding. The physiologic principles outlined here should be well understood by anyone entrusted with the care of these patients. They provide the cornerstone of diagnosis and management, and will remain valid long after current clinical dogma has been revised.

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BibTeXRIS

L Martin. 1977. Respiratory failure.. https://doi.org/10.1016/s0025-7125(16)31267-6

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The influence of vacuum extractor on fetal oxygenation and newborn status.

AIM: The aim of this study was to determine the effects of vacuum extractor assisted delivery on fetal oxygenation and acid-base balance. METHODS: Sixty-one women were enrolled in the present study. The subjects were divided into two groups. Group A, consisting of 39 women, had normal vaginal deliveries. Group B, consisting of 22 women, underwent a vacuum extractor assisted vaginal delivery. Fetal arterial oxygen saturation (SpO2) monitoring was used in all women after full cervical dilatation. After delivery, umbilical artery pH, pCO2, pO2 and base deficit (BDecf) levels were determined in all neonates. RESULTS: The mean FSpO2 value in Group A was 51.53+/-5.87% and in Group B 48.03+/-6.39% (p<0.03). The mean cord pH value in fetuses of Group A was 7.26+/-0.05, and in Group B 7.17+/-0.09. There was also a significant difference between the two groups with regards to mean pO2, pCO2 and BDecf values. CONCLUSIONS: Vacuum assisted vaginal delivery was associated with lower fetal arterial oxygen saturation levels as well as lower cord blood pH values compared to those seen after unassisted vaginal delivery. Although decreased, however, the above parameters remained within normal ranges.

Acid-Base Imbalance↗

An amniotic fluid index < or =5 cm within 7 days of delivery in the third trimester is not associated with decreasing umbilical arterial pH and base excess.

OBJECTIVE: To determine if an amniotic fluid index (AFI) < or =5.0 cm within 7 days of delivery in the third trimester is associated with decreasing umbilical arterial pH and base excess. STUDY DESIGN: Cases for this retrospective cohort study were all pregnancies > or =26 weeks with intact membranes and an AFI < or =5.0 cm within 7 days of delivery between 11/99 and 7/02. Multiple gestations, aneuploid, and anomalous fetuses were excluded. Controls with an AFI >5.0 cm within 7 days of delivery were matched to each case within 1 week by gestational age. For a control group with a mean+/-SD umbilical arterial pH of 7.26+/-0.07 and alpha=0.05, a sample size of 100 would have a power of 99% to detect a difference with a study group whose mean was 7.20. Data were compared using paired Student's t-test, Mann-Whitney, Fisher's exact, chi(2) and risk ratios with 95% confidence intervals. RESULTS: In all, 131 neonates with an AFI < or =5.0 cm were matched to 131 controls with an AFI >5 cm. There was no difference in gestational age (37.6+/-3.0, 37.7+/-3.0 weeks) or birth weight (2897+/-810, 2762+/-788 g). There was no difference in umbilical artery pH (7.25+/-0.07, 7.26+/-0.07) or base excess (-3.32+/-2.59, -2.83+/-2.45 mmol/l), even in small for gestational age (SGA) infants in both groups. There was no difference in the number of SGA neonates, 5-minute Apgar <7, respiratory distress syndrome, necrotizing enterocolitis, or neurologic morbidity. Linear regression showed no correlation between AFI and either umbilical arterial pH (r=-0.00047, SE=0.001, p=0.63) or base excess (r=-0.029, SE=0.037, p=0.428). CONCLUSION: An AFI < or =5.0 cm measured within 7 days of delivery in the third trimester is not associated with decreasing umbilical arterial pH and base excess.

Acid-Base Imbalance↗

Strong ions, weak acids and base excess: a simplified Fencl-Stewart approach to clinical acid-base disorders.

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Acid-Base Imbalance↗