A Comparative Study to Evaluate the Effect of Norepinephrine and Phenylephrine in the Treatment of Post Spinal Hypotension for Caesarean Section

Background: Maternal hypotension due to spinal anaesthesia in caesarean section is commonly seen. Alongwith fluid loading, phenylephrine is used to manage the hypotension. However, this drug is associated with cardiovascular side effects. Methods: This is a prospective double blinded study which was conducted on 100 term parturients scheduled from elective caesarean section under spinal anaesthesia, randomly assigned into two groups. After spinal anaesthesia patients of group N and P were treated with norepinephrine (5mcg) and phenylephrine (50mcg) respectively as an IV bolus for hypotension. Blood pressure, heart rate, number of bolus doses given, and neonatal APGAR score was noted. Results: Patients of both groups were comparable with respect to haemodynamic parameters (HR, SBP, DBP, AND MAP). Incidence of bradycardia was higher in group P (22%, n=11) compared to group N (14%, n=7). Neonatal APGAR scores at different time intervals were similar in both groups. Conclusion: Intermittent boluses of norepinephrine were effective in the treatment of spinal anaesthesia induced hypotension during caesarean section and can be considered as an alternative to phenylephrine.

Robotics and the Airway Management

Background: Maternal hypotension due to spinal anaesthesia in caesarean section is commonly seen. Alongwith fluid loading, phenylephrine is used to manage the hypotension. However, this drug is associated with cardiovascular side effects. Methods: This is a prospective double blinded study which was conducted on 100 term parturients scheduled from elective caesarean section under spinal anaesthesia, randomly assigned into two groups. After spinal anaesthesia patients of group N and P were treated with norepinephrine (5mcg) and phenylephrine (50mcg) respectively as an IV bolus for hypotension. Blood pressure, heart rate, number of bolus doses given, and neonatal APGAR score was noted. Results: Patients of both groups were comparable with respect to haemodynamic parameters (HR, SBP, DBP, AND MAP). Incidence of bradycardia was higher in group P (22%, n=11) compared to group N (14%, n=7). Neonatal APGAR scores at different time intervals were similar in both groups. Conclusion: Intermittent boluses of norepinephrine were effective in the treatment of spinal anaesthesia induced hypotension during caesarean section and can be considered as an alternative to phenylephrine.

Successful treatment of severe adrenaline-resistant anaphylactic shock with glucagon in a patient taking a beta-blocker: a case report

Background The efficacy of glucagon for adrenaline-resistant anaphylactic shock in patients taking β-blockers is controversial. However, understanding the efficacy of glucagon is important because adrenaline-resistant anaphylactic shock is fatal. We present a case of severe adrenaline-resistant anaphylactic shock in a patient taking a β-blocker, and glucagon was effective in improving hemodynamics. Case presentation An 88-year-old woman with severe aortic stenosis and taking a selective β-1 blocker underwent transcatheter aortic valve implantation under general anesthesia. Postoperatively, she received 100 mg sugammadex, but 2 min later developed severe hypotension and bronchospasm. Suspecting anaphylactic shock, we intervened by administering adrenaline, fluid loading, and an increased noradrenaline dose. Consequently, the bronchospasm improved, but her blood pressure only increased minimally. Therefore, we administered 1 mg glucagon intravenously, and the hypotension resolved immediately. Conclusions Glucagon may improve hemodynamics in adrenaline-resistant anaphylactic shock patients taking β-blockers; however, its efficacy must be further evaluated in more cases.

Serum NT-Pro-BNP versus Noninvasive Bedside Inotropic Index in Paediatric Shock: A Contest of Myocardial Performance in Response to Fluid Loading

Background. Mild elevation of serum amino-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is associated with myocardial dysfunction. A significantly lower Smith–Madigan inotropic index (SMII) has been shown to accurately represent cardiac contractility among heart failure subjects. We aim to monitor the effect of fluid resuscitation on cardiac function among paediatric patients by measuring serum NT-pro-BNP and SMII. Methods. This is an observational study on 70 paediatric shock patients. NT-pro-BNP and noninvasive bedside haemodynamic monitoring were done by using an ultrasonic cardiac output monitor (USCOM, USCOM, Sydney, Australia). The presence of cardiac diseases was excluded. SMII was obtained from the USCOM. An increase in the stroke volume index (SVI) of ≥15% indicates fluid responders. Measurements were taken before and after fluid loading. Results. Preloading NT-pro-BNP and SMII category were significantly different between the fluid responsiveness group, p = 0.001 and p = 0.004 , respectively. Higher median NT-pro-BNP (preloading NT-pro-BNP of 1175.00 (254.50–9965.00) ng/mL vs. 196.00 (65.00–509.00) ng/mL, p = 0.002 ) was associated with fluid nonresponders (subjects >12 months old). Preloading NT-pro-BNP <242.5 ng/mL was associated with fluid responders (AUC: 0.768 (0.615–0.921), p = 0.003 ), 82.1% sensitivity, and 68.7% specificity for subjects >12 years old. Delta NT-pro-BNP in fluid responders (15.00 (−16.00–950.00) ng/mL) did not differ from fluid nonresponders (505.00 (−797.00–1600.00) ng/mL), p = 0.456 . Postloading SMII >1.25 W·m−2 was associated with fluid responders (AUC: 0.683 (0.553–0.813), p = 0.011), 61.9% sensitivity, and 66.7% specificity, but not preloading SMII. Fluid responders had a higher mean postloading SMII compared to nonresponders (1.36 ± 0.38 vs. 1.10 ± 0.34, p = 0.006 ). Conclusion. Higher NT-pro-BNP and lower SMII in the absence of cardiac diseases were associated with poor response to fluid loading. The SMII is affected by low preload conditions.

Norepinephrine as an Alternative in Hypotension Prophylaxis During Cesarean Sectionunder Spinal Anesthesia

Background Spinal anesthesia is the preferred method for elective cesarean sections (C.S.) due to considerable risks regarding airway management associated with physiological changes of pregnancy. Hypotension is reported to occur in up to 80% of spinal anesthesia cases. Many approaches have been investigated to prevent spinal hypotension, e.g., fluid loading, vasopressors, or both. Thus we compare the administration of intermittent I.V. boluses of norepinephrine and ephedrine to guard against the hypotensive effect of spinal anesthesia during cesarean delivery. Patients and Methods 120 female patients undergoing electiveC.S.were randomly divided into “group-E” for Ephedrine and “group-N” for Norepinephrine. Results Compared with ephedrine, norepinephrine maintained maternal blood pressure and uterine artery blood flow. Further, it was associated with lower numbers of hypotension and hypertension episodes and less frequency of bradycardia and tachycardia during cesarean delivery. Conclusion Norepinephrine can be used as an alternative vasopressor to maintain maternal blood pressure during spinal anesthesia for cesarean delivery, with no adverse effect on neonatal outcome.

The vibrational response of a fluid-loaded baffled plate near a free surface

An analytical model to predict the vibrational response of a simply supported rectangular plate embedded in an infinite baffle with an upper free surface under heavy fluid loading and excited by a point force is presented. The equations of motion of a thin plate are solved using­­­­­­ modal decomposition technique by employing admissible functions for an in-vacuo plate and by directly solving the Helmholtz equation for acoustic waves in a fluid. The vibrational response for a flat plate in an infinite baffle and unbounded domain (semi-infinite domain) using analytical formulation available in literature is initially computed. These results are then compared against present results to observe the effect of a free surface. Predictions from analytical models are validated by comparison with results obtained by numerical models. The proposed analytical approach presents a novel formulation to describe a fluid-loaded flat plate in a waveguide and an efficient method for predicting its vibrational response.

Tutorial on Acoustic Fluid Loading of Structures

Any vibrating structure is loaded by the fluid surrounding it. Whether air, water, or something else, the fluid loading adds a spatially distributed resistance (in phase with the vibration) and reactance (out of phase with the vibration) over the structural surfaces. The resistance absorbs energy, and damps structural vibrations. The reactance is either mass-like, effectively adding to the structural density, reducing resonance frequencies and vibration amplitudes; or stiffness-like, increasing resonance frequencies. Usually, mass-like reactance is caused by fluids external to a structure, and stiffness-like reactance is caused by enclosed volumes of fluids. This tutorial uses analytic methods to compare and contrast external and internal fluid loading on a flat rectangular plate and demonstrates the effects of fluid loading on plate vibration and radiated sound. The well-known stiffening effect of the internal Helmholtz resonance is demonstrated for a thin panel and a shallow entrained cavity. The differences between heavy (water) and light (air) external fluid loading are also demonstrated, with significant reductions in resonance frequencies and peak vibration amplitudes for water loading.