title: Isoflurane versus sevoflurane with interscalene block for shoulder arthroscopic procedures: Value of process capability indices as an additional tool for data analysis.
abstract: OBJECTIVE
  Hypotensive anaesthesia reduces intra-articular bleed and promotes visualisation during arthroscopy. The haemodynamic effects of inhalational agents isoflurane and sevoflurane were studied extensively, and both were found to reduce mean arterial pressures (MBP) to an equivalent magnitude. We investigated the relative ability of isoflurane vis-a-vis sevoflurane to maintain the target systolic blood pressure (SBP) in patients undergoing shoulder arthroscopic procedures.
  
  
  METHODS
  In a prospective randomised study, 59 patients in two groups of 30 and 29 patients each received concomitant general anaesthesia (1.2-1.5 MAC of isoflurane and sevoflurane) and interscalene brachial plexus block. Nitrous oxide was used in both groups. Intraoperatively, serial blood pressure recordings of SBP, diastolic blood pressure (DBP), MBP and heart rates were done at every 3rdmin intervals. The manipulations needed to achieve target SBP (T= 90 mmHg) for optimal arthroscopic visualisation and treat unacceptable hypotensive episodes were noted. Conventional statistical tests and process capability index (PCI) evaluation were both deployed for data analysis.
  
  
  RESULTS
  Lower mean SBP and DBPs were recorded for isoflurane patients as compared to sevoflurane (P< 0.05, for mean, maximum and minimum recordings). Higher mean heart rates were recorded for isoflurane (P< 0.05). PCIs indicated that isoflurane was superior to sevoflurane in the ease of achieving target SBP of 90 mmHg as well as maintaining blood pressures in the range of 80-100 mmHg.
  
  
  CONCLUSIONS
  Isoflurane provides better intraoperative haemodynamic status vis-a-vis sevoflurane in patients undergoing shoulder arthroscopic surgery with preliminary interscalene blockade. The PCI can be a useful additional medical data analysis tool.
authors.affiliation: Department of Anaesthesiology, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka, India.
authors.forename: Thrivikrama Padur
authors.initials: TP
authors.lastname: Tantry
authors.affiliation: Department of Anaesthesiology, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka, India.
authors.forename: Harish
authors.initials: H
authors.lastname: Karanth
authors.affiliation: Department of Urology, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka, India.
authors.forename: Sunil P
authors.initials: SP
authors.lastname: Shenoy
authors.affiliation: Department of Quality, Infosys Limited, Electronics City, Phase 1, Bengaluru, Karnataka, India.
authors.forename: Shreekantha V
authors.initials: SV
authors.lastname: Ayya
authors.affiliation: Department of Anaesthesiology, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka, India.
authors.forename: Pramal K
authors.initials: PK
authors.lastname: Shetty
authors.affiliation: Department of Anaesthesiology, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka, India.
authors.forename: Karunakara K
authors.initials: KK
authors.lastname: Adappa
keywords: Isoflurane; process capability index; sevoflurane; shoulder arthroscopy; volatile anaesthetic