Quantitative Assessment of Nitrous Oxide Levels in Room Air of Operation Theaters and Recovery Area: An Observational Study.

BACKGROUND: Nitrous oxide has been used during surgical anesthesia for many years. However, information about occupational exposure and related risks due to N2O exposure to the health care personnel in India are still poorly understood. Here, we measured the residual N2O levels during the working time of operation theatre room air in our tertiary care hospital. MATERIAL AND METHODS: The air samples were collected from different anesthesia exposure zones on different days for quantitative analysis of available N2O in the room air in respective areas. Nitrous oxide concentrations in the ambient air were also measured to compare outdoor and indoor levels. OBSERVATIONS AND RESULTS: Nitrous oxide mixing ratios were found to be 65.61 ± 0.05 ppm, 281.63 ± 0.43 ppm, and 165.42 ± 0.42 ppm in elective surgical theatres of the hospital on three different days whereas in emergency operation theatres of the same hospital levels of N2O were 166.75 ± 0.07 ppm, 510.19 ± 0.30 ppm and 2443.92 ± 0.64 ppm during same period. In elective pediatric surgical theatres levels of N2O were found to be 1132.55 ± 0.70 ppm and 362.21 ± 0.13 ppm on two days of reading respectively. Outdoor levels of N2O in contrast found 0.32 ± 0.01 ppm and was lower by a factor of 1000. CONCLUSION: We observed the very high ambient concentration of N2O in the surgical theatre's environment (up to 2443 ppm) and recovery areas (up to 50 ppm). It was 5 to 50 times higher ambient concentration of N2O than REL in OT area and 200-7000 times higher ambient concentration of N2O than outdoor ambient air in all surgical theaters other than CTVS OTs.

Closed-loop isoflurane administration with bispectral index in open heart surgery: randomized controlled trial with manual control.

OBJECTIVE: Improved anesthetic agent delivery system (IAADS), a modification of closed-loop anesthesia delivery system (CLADS), is designed to deliver inhalational anesthetics and propofol through closed-loop control with bispectral index (BIS) as target. We compared the performance of IAADS with the manual control isoflurane administration during cardiac surgery. METHODS: Forty patients of ASA (American Society of Anesthesiologists) physical status class II-III, undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) in a tertiary care hospital in India were randomized to receive isoflurane through a closed-loop system (IAADS group) or through a Tech 7 vaporizer adjusted manually (manual group) to achieve a target BIS of 50. Patients were induced with a propofol infusion and isoflurane was started after intubation. During CPB, patients received propofol; isoflurane was restarted after separation from CPB. The efficacy of IAADS in controlling depth of anesthesia and hemodynamic variations was compared with that of manual control. RESULTS: IAADS was able to maintain BIS within ± 10 of target for significantly longer period (84.6 ± 7.2% in IAADS group vs. 75.9 ± 11.2 in manual group, p < 0.01). Both overall performance, as assessed by global score (p < 0.01), and precision, as judged by median absolute performance error (MDAPE) (p < 0.04), were significantly better in the IAADS group. The IAADS group required significantly less propofol for induction (1.3 ± 0.4 mg/kg in IAADS vs. 1.6 ± 0.5 mg/kg in manual, p < 0.05) and less isoflurane during maintenance of anesthesia (3.3 ± 0.8 ml/h vs. 3.4 ± 0.9 ml/h, p < 0.01). CONCLUSION: The present study proves the feasibility and efficacy of inhalation anesthetic administration through closed-loop control. This is the first system that has been developed to control intravenous and inhalational anesthetic agents in a closed-loop model using BIS.

Closed-loop anaesthesia delivery system (CLADS) using bispectral index: a performance assessment study.

The development of electroencephalographic indices of anaesthetic depth has in turn generated interest in automated anaesthesia delivery systems using these as the input variable. In this paper, one patented closed loop anaesthesia delivery system (CLADS) (502/DEL/2003) is compared to manual control of propofol delivery titrated to the bispectral index (BIS). Forty ASA I-II patients undergoing elective surgery under general anaesthesia were enrolled in the study. The study participants were randomised using computer generated random numbers to two equal groups. One group received propofol titrated by the CLADS while in the other group (control), anaesthetic delivery was manually titrated to BIS. Closed loop anaesthetic delivery using our patented system led to lower induction doses of propofol (P < 0.05) and less overshoot of the target BIS (P < 0.05). The closed loop system maintained BIS to within +/-10 of target for a significantly longer time during the maintenance phase of anaesthesia (P < 0.01). Smaller amounts of anaesthetic agent were required (P < 0.01) and there was faster postoperative recovery (P < 0.05). Manual delivery of propofol required the infusion rate to be changed a median of 30 times (IQR 12-45), which required considerable time and attention by the anaesthetist. In conclusion, automated delivery of propofol adjusted to the bispectral index using our CLADS was both effective and efficient as compared to manual control.

Drug utilization pattern in the intensive care unit of a tertiary care hospital.

The authors studied the factors affecting drug use pattern, cost of therapy, and the association between the pattern of drug use and survival as well as the duration of stay in a prospective, observational study in an intensive care unit between February and May 2005. Data were collected regarding drugs used, severity of the disease, and their outcome. The mean +/- SD of the Acute Physiology and Chronic Health Evaluation (APACHE III) and Glasgow Coma Scale (GCS) scores of 84 patients were 52.2 +/- 19.4 and 7.5 +/- 2.4, respectively. Although the mean number of drugs at the time of admission to the intensive care unit was 5.3, it increased to 12.9 on the first day and 22.2 during the entire stay. More than 50% of the average expenditure on drugs and nutrition was accounted by antibiotics. Requirement of insulin or inotropes signified an adverse outcome on mortality (odds ratios of 3.43 and 8.44, respectively). In conclusion, there is a tremendous impact of antibiotic use on the cost of therapy in the intensive care unit. The requirement of certain drugs such as insulin and inotropes is of prognostic significance.

Assessment of intraoperative blood transfusion practice during elective non-cardiac surgery in an Indian tertiary care hospital.

BACKGROUND: We assessed appropriate intraoperative use of whole blood during elective surgery. METHODS: This prospective observational audit by a team of anaesthetists over 3 months in a multi-speciality tertiary care teaching hospital used strict preset criteria to evaluate the use of blood transfusion during elective surgery by anaesthetists. The criteria used to evaluate the rate of appropriate transfusion were haemoglobin less than 8 g x dl(-1), haemoglobin less than 10 g x dl(-1) in patients with medical co-morbidities and blood loss greater than 20% of blood volume when more than 1000 ml. RESULTS: The overall rate of appropriate use of blood was 40.7%; it was inappropriate in 19.2% of cases (haemoglobin >11 g x dl(-1)). The primary trigger was low haemoglobin (measured intraoperatively or derived from blood loss). Patients in whom haemoglobin was measured intraoperatively had a significantly higher appropriate use of blood (P<0.05). There was a reduction in blood use over the 3-month audit period (P<0.05). CONCLUSIONS: Current intraoperative blood use is sub-optimal. Intraoperative haemoglobin estimation is an effective and simple measurement to improve appropriate use of blood. The indication for transfusion should be recorded in the case notes.

Severe head injury patients in a multidisciplinary ICU: are they a burden?

OBJECTIVE: Patients with severe head injury (HI) are often considered to be a burden in a multidisciplinary intensive care unit (ICU). This study was undertaken to compare the severe closed HI patients with all other patients in the ICU in terms of age group involved, stay in the unit, complications and outcome. DESIGN: Retrospective analysis. SETTING: Multidisciplinary ICU of a tertiary care hospital in Northern India. PATIENTS AND PARTICIPANTS: All the patients admitted to the ICU between January 1995 and December 1997. The patients were classified into two groups: group A comprising patients with severe closed HI and group B consisting of all other patients. RESULTS: The mean age of the patients was around 30 years in both the groups. The average stay of the patients in the unit was 12.71 +/- 11.9 days in group A, compared to 9.9 +/- 14.4 days for group B (p < 0.05). The duration on the ventilator or on an endotracheal airway was not different between the groups (p > 0.05). The mortality in group A was 46.8 % and that in group B was 38.5 % (p > 0.05). The mortality was directly proportional to the age in group A. Hypotension, renal failure and septicaemia were the commonest complications in both the groups but the difference was not statistically significant. CONCLUSIONS: This study demonstrates that patients with severe HI do not pose an extra burden in a multidisciplinary ICU.