Horstman DJ, Riley ET, Carvalho B A randomized trial of maximum cephalad sensory blockade with single-shot spinal compared with combined spinal-epidural techniques for cesarean delivery. Anesth Analg. 2009 Jan;108(1):240-5. doi: 10.1213/ane.0b013e31818e0fa6.
Kozanhan B, Bardak O, Sami Tutar M, Ozler S, Yildiz M, Solak I The influence of Body Roundness Index on sensorial block level of spinal anaesthesia for elective caesarean section: an observational study. J Obstet Gynaecol. 2020 Aug;40(6):772-778. doi: 10.1080/01443615.2019.1647523. Epub 2019 Aug 30.
Kuok CH, Huang CH, Tsai PS, Ko YP, Lee WS, Hsu YW, Hung FY Preoperative measurement of maternal abdominal circumference relates the initial sensory block level of spinal anesthesia for cesarean section: An observational study. Taiwan J Obstet Gynecol. 2016 Dec;55(6):810-814. doi: 10.1016/j.tjog.2015.04.009.
Prediction of Block Height of Spinal Anesthesia Via Machine Learning Approach
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.