Norepinephrine Infusion for Preventing Postspinal Anesthesia Hypotension during Cesarean Delivery: A Randomized Dose-finding Trial.

BACKGROUND: Norepinephrine has been recently introduced for prophylaxis against postspinal hypotension during cesarean delivery; however, no data are available regarding its optimum dose. The objective of this study is to compare three infusion rates of norepinephrine for prophylaxis against postspinal hypotension during cesarean delivery. METHODS: The authors conducted a double-blinded, randomized, controlled study including full-term pregnant women scheduled for cesarean delivery. Norepinephrine infusion was commenced after subarachnoid block. Patients were randomized into three groups, which received norepinephrine with starting infusion rates of 0.025 µg · kg(-1) · min(-1), 0.050 µg · kg(-1) · min(-1), and 0.075 µg · kg(-1) · min(-1). Infusion was stopped when intraoperative hypertension occurred. The primary outcome was the frequency of postspinal hypotension (defined as decreased systolic blood pressure less than 80% of the baseline reading). The three groups were compared according to the following: systolic blood pressure, heart rate, frequency of intraoperative hypertension, frequency of bradycardia, and neonatal outcomes. RESULTS: Two hundred eighty-four mothers were included in the analysis. The frequency of postspinal hypotension was lower for both the 0.050-µg · kg(-1) · min(-1) dose group (23/93 [24.7%], odds ratio: 0.45 [95% CI: 0.24 to 0.82], P = 0.014) and the 0.075-µg · kg(-1) · min(-1) dose group (25/96 [26.0%], odds ratio: 0.48 [95% CI:0.26 to 0.89], P = 0.022) compared with the 0.025-µg · kg(-1) · min(-1) dose group (40/95 [42.1%]). The two higher-dose groups (the 0.050-µg · kg(-1) · min(-1) group and the 0.075-µg · kg(-1) · min(-1) group) had higher systolic blood pressure and lower heart rate compared with the 0.025 µg · kg(-1) · min(-1) group. The three groups were comparable in the frequency of intraoperative hypertension, incidence of bradycardia, and neonatal outcomes. CONCLUSIONS: Both the 0.050-µg · kg(-1) · min(-1) and 0.075-µg · kg(-1) · min(-1) norepinephrine infusion rates effectively reduced postspinal hypotension during cesarean delivery compared with the 0.025-µg · kg(-1) · min(-1) infusion rate.

Variable versus fixed-rate infusion of phenylephrine during cesarean delivery: a randomized controlled trial.

BACKGROUND: Phenylephrine is the most commonly used vasopressor for prophylaxis against maternal hypotension during cesarean delivery; however, the best regimen for its administration is not well established. Although variable infusion protocols had been suggested for phenylephrine infusion, evidence-based evaluation of variable infusion regimens are lacking. The aim of this work is to compare variable infusion, fixed on-and-off infusion, and intermittent boluses of phenylephrine for prophylaxis against maternal hypotension during cesarean delivery. METHODS: A randomized controlled study was conducted, including full-term pregnant women scheduled for elective cesarean delivery. Participants were divided into three groups which received phenylephrine by either intermittent boluses (1.5 mcg/Kg phenylephrine), fixed on-and-off infusion (with a dose of 0.75 mcg/Kg/min), or variable infusion (with a starting dose of 0.75 mcg/Kg/min). The three groups were compared with regard to frequency of: maternal hypotension (primary outcome), second episode hypotension, reactive hypertension, and bradycardia. Other outcomes included heart rate, systolic blood pressure, physician interventions, and neonatal outcomes. RESULTS: Two-hundred and seventeen mothers were available for final analysis. The 2 infusion groups showed less incidence of maternal hypotension {26/70 (37%), 22/71 (31%), and (51/76 (67%)} and higher incidence of reactive hypertension compared to the intermittent boluses group without significant differences between the two former groups. The number of physician interventions was highest in the variable infusion group compared to the other two groups. The intermittent boluses group showed lower systolic blood pressure and higher heart rate compared to the two infusion groups; whilst the two later groups were comparable. CONCLUSION: Both phenylephrine infusion regimens equally prevented maternal hypotension during cesarean delivery compared to intermittent boluses regimen. Due to higher number of physician interventions in the variable infusion regimen, the current recommendations which favor this regimen over fixed infusion regimen might need re-evaluation.

Evaluation of the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease.

BACKGROUND: Dexmedetomidine infusion improves oxygenation and lung mechanics in patients with chronic obstructive lung disease; however, its effect in patients with restrictive lung disease has not been thoroughly investigated yet. The aim of this work was to evaluate the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease. METHODS: Forty-two morbidly obese patients scheduled for bariatric surgery were included in the study. Patients were randomized to receive either dexmedetomidine infusion at a bolus dose of 1mcg/Kg followed by infusion at 1 mcg/Kg/hour for 90 min (Dexmedetomidine group), or normal saline infusion (Control group). Both groups were compared with regard to: oxygenation {P/F ratio: PaO2/fraction of inspired oxygen (FiO2)}, lung compliance, dead space, plateau pressure, blood pressure, and heart rate. RESULTS: Dexmedetomidine group showed significant improvement of the PaO2/FiO2 ratio, and higher lung compliance compared to control group by the end of drug infusion. Dexmedetomidine group demonstrated decreased dead space, plateau pressure, blood pressure, and heart rate compared to control group by the end of drug infusion. CONCLUSION: A 90-min dexmedetomidine infusion resulted in moderate improvement in oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease. TRIAL REGISTRATION: clinicaltrials.gov : NCT02843698 on 20 July 2016.

Hemodynamic effects of lateral tilt before and after spinal anesthesia during cesarean delivery: an observational study.

BACKGROUND: Post-spinal hypotension is a common maternal complication during cesarean delivery. Aortocaval compression by the gravid uterus has been assumed as a precipitating factor for post-spinal hypotension. The role of left lateral tilting position in improving maternal cardiac output after subarachnoid block (SAB) is unclear. The aim of this work is to investigate the effect of left lateral tilting on maternal hemodynamics after SAB. METHODS: A prospective observational study was conducted including 105 full term pregnant women scheduled for cesarean delivery. Mean arterial pressure, heart rate, cardiac output (measured by electrical cardiometry), stroke volume, and systemic vascular resistance were recorded in three positions (supine, 150, and 300 left lateral positions) before SAB, after SAB, and after delivery of the fetus. RESULTS: Before SAB, no significant hemodynamic changes were reported with left lateral tilting. A significant decrease was reported in mean arterial pressure, cardiac output, stroke volume, and systemic vascular resistance after SAB (in supine position). When performing left lateral tilting, there was an increase in cardiac output, heart rate, and mean arterial pressure. No difference was reported between the two tilt angles (150 and 300). CONCLUSIONS: Changing position of full term pregnant woman after SAB from supine to left lateral tilted position results increased cardiac output and mean arterial pressure. There is no difference between the two tilt angles (150 and 300). TRIAL REGISTRATION: clinicaltrials.gov ( NCT02828176 ) retrospectively registered.

Thermal Imaging to Predict Failed Supraclavicular Brachial Plexus Block: A Prospective Observational Study.

Background: Successful brachial plexus blockade produces sympathetic blockade, resulting in increased skin temperature in the blocked segments. This study aimed to evaluate the accuracy of infrared thermography in predicting failed segmental supraclavicular brachial plexus block. Methods: This prospective observational study included adult patients undergoing upper-limb surgery under supraclavicular brachial plexus block. Sensation was evaluated at the dermatomal distribution of the ulnar, median, and radial nerves. Block failure was defined as absence of complete sensory loss 30 min after block completion. Skin temperature was evaluated by infrared thermography at the dermatomal supply of the ulnar, median, and radial nerves at baseline, 5, 10, 15, and 20 min after block completion. The temperature change from the baseline measurement was calculated for each time point. Outcomes were the ability of temperature change at each site to predict failed block of the corresponding nerve using area under receiver-operating characteristic curve (AUC) analysis. Results: Eighty patients were available for the final analysis. The AUC (95% confidence interval [CI]) for the ability of temperature change at 5 min to predict failed ulnar, median, and radial nerve block was 0.79 (0.68-0.87), 0.77 (0.67-0.86), and 0.79 (0.69-0.88). The AUC (95% CI) increased progressively and reached its maximum values at 15 min (ulnar nerve 0.98 [0.92-1.00], median nerve 0.97 [0.90-0.99], radial nerve 0.96 [0.89-0.99]) with negative predictive value of 100%. Conclusion: Infrared thermography of different skin segments provides an accurate tool for predicting failed supraclavicular brachial plexus block. Increased skin temperature at each segment can exclude block failure in the corresponding nerve with 100% accuracy.

Hemodynamic effects of norepinephrine versus phenylephrine infusion for prophylaxis against spinal anesthesia-induced hypotension in the elderly population undergoing hip fracture surgery: a randomized controlled trial.

BACKGROUND: Elderly population are at increased risk of spinal anesthesia-induced hypotension increasing their risk for postoperative morbidity and mortality. This study aimed to compare the hemodynamic effects of prophylactic infusion of norepinephrine (NE) versus phenylephrine (PE) in elderly patients undergoing hip fracture surgery under spinal anesthesia. METHODS: Elderly patients scheduled for hip fracture surgery were randomized to receive either NE infusion (8 µg/min) (NE group, n = 31) or PE infusion (100 µg/min) (PE group, n = 31) after spinal anesthesia. Outcomes included mean heart rate, mean blood pressure, cardiac output, incidence of spinal anesthesia-induced hypotension, incidence of bradycardia, and incidence of hypertension. RESULTS: Sixty-two patients with a mean age of 71 ± 6 years were included in the final analysis (31 patients in each group). The NE group showed a higher mean heart rate and cardiac output than the PE group. The NE group had a lower incidence of reactive bradycardia (10% vs. 36%, P = 0.031) and hypertension (3% vs. 36%, P = 0.003) than the PE group. No study participant developed hypotension, and the mean blood pressure was comparable between the two groups. CONCLUSIONS: Both NE and PE infusions effectively prevented spinal anesthesia-induced hypotension in elderly patients undergoing hip fracture surgery. However, NE provided more hemodynamic stability than PE; maintaining the heart rate, higher cardiac output, less reactive bradycardia, and hypertension.

Norepinephrine versus phenylephrine infusion for prophylaxis against post-spinal anaesthesia hypotension during elective caesarean delivery: A randomised controlled trial.

BACKGROUND: Prophylactic vasopressors are fundamental during caesarean delivery under spinal anaesthesia. The aim of this work is to compare the efficacy and safety of phenylephrine and norepinephrine when used in variable infusion rate during caesarean delivery. METHODS: A randomised, double-blinded, controlled trial was conducted including mothers scheduled for elective caesarean delivery under spinal anaesthesia. Participants were allocated to two groups norepinephrine group (n = 60), and phenylephrine group (n = 63). Participants received prophylactic vasopressors after spinal block at rate started at 0.05 mcg/kg/min and 0.75 mcg/kg/min respectively. The rate of vasopressor infusion was manually adjusted according to maternal systolic blood pressure. Both groups were compared according to incidence of post-spinal hypotension (the primary outcome), incidence of bradycardia, incidence of reactive hypertension, systolic blood pressure, heart rate, rescue vasopressor consumption, number of physician interventions, and neonatal outcomes. RESULTS: One hundred and twenty-three mothers were available for final analysis. Both groups were comparable in the incidence of post-spinal hypotension (32% versus 30%, P = 0.8). The number of physician intervention was lower in norepinephrine group. The incidence of bradycardia and the incidence of reactive hypertension were potentially lower in norepinephrine group without reaching statistical significance, (13% vs. 21%, P = 0.3) and (12% vs. 24%, P = 0.1). Rescue vasopressor consumption, and neonatal outcomes were comparable between both groups. CONCLUSION: When given in a manually adjusted infusion, norepinephrine effectively maintained maternal SBP during caesarean delivery under spinal anaesthesia with lower number of physician interventions, and likely less incidence of reactive hypertension and bradycardia compared to phenylephrine.

Current Gastrointestinal Imaging in Children.

Gastrointestinal (GI) pathologies in children present with overlapping symptoms and signs. Radiological imaging is assuming a more prominent role in the diagnostic pathway. This article is aimed primarily at paediatricians, helping them to understand and thereby better utilise radiological imaging. The strengths and weaknesses of the various imaging modalities are outlined in a concise manner. Illustrative conditions are discussed with an emphasis on key diagnostic features along with several, high quality annotated images. Emerging concepts are introduced throughout the article. These are referenced by the latest research to give the reader an update of current GI imaging in children.