The Management of Spinal and Epidural Anesthesia-Related Hypotension in the United States During Cesarean Childbirth.

This study delves into the prevalence of spinal anesthesia-induced hypotension during cesarean (c-section) childbirth, focusing on existing treatments and their efficacy. Currently, neuraxial analgesia is the most efficient method for alleviating pain during c-sections, but its major side effect, hypotension, necessitates a thorough understanding of the available treatment options. A scoping review was conducted using PubMed and Rayyan, with inclusion criteria being English peer-reviewed articles from the last five years, involving nulligravida/primigravida women under 35 years old in the United States. The research reveals various treatments to mitigate spinal anesthesia-induced hypotension. Norepinephrine and epinephrine have demonstrated effectiveness in maintaining blood pressure while reducing adverse maternal outcomes following delivery. When comparing fixed-rate infusions of norepinephrine to phenylephrine, norepinephrine demonstrated lower rates of bradycardia (p=0.004), thereby reducing the necessity for bolus atropine rescue (p=0.01). Furthermore, the use of colloid solutions during c-sections significantly decreased the incidence of hypotension when compared to crystalloid solutions (p<0.00001). Non-pharmacological methods, such as lower extremity wrapping and elevation, exhibited higher systolic and diastolic blood pressures, along with higher usage of ephedrine when compared to control groups. Pharmacological treatments proved more effective than non-pharmacological interventions in preventing maternal hypotension during c-sections. Notably, colloid preloading emerged as the most effective approach, helping to maintain maternal blood pressure, cardiac output, and heart rate while also minimizing the amount of ephedrine required and reducing anesthesia-related adverse effects. However, the study suggests the need for further investigations to determine the optimal dosage for colloid preloading. This research provides valuable insights into enhancing maternal well-being during c-sections by addressing the issue of neuraxial anesthesia-induced hypotension.

Endothelial alpha globin is a nitrite reductase.

Resistance artery vasodilation in response to hypoxia is essential for matching tissue oxygen and demand. In hypoxia, erythrocytic hemoglobin tetramers produce nitric oxide through nitrite reduction. We hypothesized that the alpha subunit of hemoglobin expressed in endothelium also facilitates nitrite reduction proximal to smooth muscle. Here, we create two mouse strains to test this: an endothelial-specific alpha globin knockout (EC Hba1Δ/Δ) and another with an alpha globin allele mutated to prevent alpha globin's inhibitory interaction with endothelial nitric oxide synthase (Hba1WT/Δ36-39). The EC Hba1Δ/Δ mice had significantly decreased exercise capacity and intracellular nitrite consumption in hypoxic conditions, an effect absent in Hba1WT/Δ36-39 mice. Hypoxia-induced vasodilation is significantly decreased in arteries from EC Hba1Δ/Δ, but not Hba1WT/Δ36-39 mice. Hypoxia also does not lower blood pressure in EC Hba1Δ/Δ mice. We conclude the presence of alpha globin in resistance artery endothelium acts as a nitrite reductase providing local nitric oxide in response to hypoxia.