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Journal of the Academy of Hospital Administration

Estimation of Sterilization Capacity in Superspecialty Tertiary Care Hospital in South East Asia Region

Author(s): P.C. Chaubey*, Rampal**

Vol. 17, No. 2 (2005-01 - 2005-12)

Key Words: Sterilization, CSSD, Capacity, Cycle-time, Utilization, Autoclaves, Net Sterilization Capacity, Total Sterilization Capacity, Nosocomial

Key Messages:

  • Healthcare Institute must have economical arrangements of prevention of hospital infection
  • Volume of space required/day is an effective way to estimate sterilization capacity


The 21st century is seeing increased role of tertiary care organizations in specialist (super) health care delivery systems. In the age of globalization and effective information dissemination, the level of awareness has increased. Moral and legal connotations of health care delivery have made tremendous impact on how hospital services are to be planned. Following the concept of "Do No Further Harm", the hospitals are ethically bound to control Nosocomial infections. This makes a well planned sterilization service imperative. In planning of a Sterile supply department, the key points to be kept in mind include the hospital's sterilization policy regarding centralization / de-centralization, the number of consumer departments, the total number of hrs of functioning in 24 hrs, the turnover rate and number of the items requiring sterilization. Based on the above factors estimate of the volume of sterilization space required for one bed can be derived. This would help in procuring of optimal number of autoclaves of the right capacity. It was concluded from the study that a super-specialty hospital utilizes 0.665 cubic feet of sterilization space per bed in 24 hours. Keeping buffer for maintenance downtime, the optimal 'Total Sterilization Capacity' is 0.730 cu ft per Bed for 24 Hrs.


'Infections' have been an insolent aspect of health care, since the inception of its understanding. Control over these infections is the moral incumbency thrust upon the health care professionals by virtue of its relation to life. A hospital acquired infection, negates all of its otherwise appreciated philanthropic effort of reducing human suffering.


'Hotel Dieu' in Paris was founded in the 7th century and was one of the first hospitals before renaissance. It grew in all aspects over the centuries, but even until the 1700s, it did not have any infection control practices in place. British Hospital's during that period were better because of their cleanliness. The Manchester infirmary in the years 1770s had a policy of clean sheets on admission, change of sheets once a week and one patient on one bed. These did contribute to reduced infections. "Semmelweis" (1840s-1860s) studied the patients in labor and stumbled upon 'contamination' as a major cause of morbidity and mortality. "Florence Nightingale" in the year 1863, gave a remarkable statement in favor of domiciliary treatment to avoid death. The reason for making the statement was probably her observations regarding poor contamination-prevention practices in those days. In 1860s, Lister, Professor of Surgery in University of Glasgow chose 'Carbolic Acid' as a tool and proposed the 'Antiseptic System'. From 1890 to 1950s German surgeons accepted Lister's methods. This further evolved from 'Antisepsis' to an intellectually superior concept of 'Asepsis'. Bacteria could now be destroyed by heat and by the 191Os, sterile instruments, gowns, masks and gloves were a standard in the large university hospitals (1).


"Sterilization" is an absolute term, meaning "destruction of all life". It has now become the most recognized and respected agent of destroying microorganisms. Technically, it is defined as 'decrease in the microbial load by 10-6 '. It is possible by two methods, physical and chemical (2). The physical method used most often is the steam sterilization (Autoclaving). Autoclave is equipment, which uses moist heat to sterilize various reusable items in a hospital and biomedical waste. Moist and dry steam sterilization causes death of the bacterial cells and spores in an exponential manner. The viruses are generally more resistant to thermal deactivation (3).


It is acknowledged that even in the advanced countries, approximately 5% of all the patients develop infection after being admitted. It adds to the tangible and intangible cost by way of unnecessary suffering, extra-hospitalization and loss of working days (4). Hence, it is imperative for a health care set up to have an economical arrangement for preventing such Nosocomial infections. Most of the modem day hospitals have in-house Central Sterile Supply Department (CSSD) housing mostly autoclaves for sterilization purposes. The responsibilities of the CSSD are to clean, decontaminate, test, prepare for use, sterilize, store and issue to the user areas the sterile equipments for use. The volume of the activity in the CSSD depends on:

  • The hospital policy (with regard to centralized/ de-centralized sterilization system).
  • Number of departments served with special focus on relative needs of the individual departments.
  • Number of items and pieces used by the departments,
  • Number of sets of items of a particular type in the circulation.
  • The turnaround time (which in turn depends on the number of surgeries per shift, number of shifts of work)

No specific standards are formulated for CSSD capacity in terms of "cubic feet of volume per bed", with regard to super-specialty hospitals. Attempt is made in this study to arrive at an estimate requirement for such a hospital in SE Asia, keeping in mind the similar geo-politicocultural denominations in the region.


A tertiary care, super-specialty hospital was studied in terms of, number of departments served with special focus on relative needs of the individual departments & the existent system in the CSSD.

A descriptive study of two weeks duration was done to estimate the available capacity and utilization of the CSSD by considering the shifts in which the CSSD functions, number of machines in hand & those in use, capacity of the machines and the cycle time for a single load. The study duration had normal functioning of the hospital with no extraordinary workloads or holidays.

Open-ended interviews were conducted with the user departments regarding quality & quantity of the sterile supply from the CSSD, with special attention to surgical departments (since surgery & allied department are the most intense users of the CSSD facilities). The sister-in-charges of the user departments were interviewed to find out any cancellations due to lack of / shortage of, the required amount of supply from the CSSD, any complaints with regard to stains or any evidence of improper cleaning or sterilizing process in even a single set received from the CSSD. The above interviews were made with respect to the study duration.


  • The characteristics of the tertiary care hospital under study: were as follow:
  • 1846 bedded
  • Personnel: Bed ratio = 3.8
  • 27 specialties including 15 super-specialties
  • Annual In-Patients admission = approx -9S,000, with Average Length of Stay of 5.4 days.
  • Annual no. of surgeries performed (major + minor) = approx-l,lO,OOO
  • Annual OPD attendance= approx- 16,00,000
  • Crude Infection Rate of 9%
  • Proportional bed distribution:

Table 1: General ward beds

Specialty beds -
( as % of total beds)
Super-specialty beds -
(as % of total beds)
Medicine- 3.7 Cardiac Sciences-6.4
Surgery-4.0 Neuro Sciences-8.2
Dermatology-2 Endocrinology-1.S
Psychiatry-1.6 Gastro-enterology +GI Surgery-3.5
Orthopaedics + PMR- 2.5 Nephrology + Urology 3.6
OBG-4.6 Pediatric Surgery - 2
Paediatrics-5.1 Cancer-IO.8
Hematology-I. Neonatology-I. 1
1 Ophthalmology 16.25  
Emergency-4.8 Dental Surgry-O.2
Total - 46.55 % Total - 38.4 %

Private Ward beds- 5.6 %

Table 2: ICU + HDU Beds

Specialty beds - ( as % of total beds) Super-specialty beds - (as % of total beds)
General + Medicine + Neurosciences + Paediatrics+ Surgery= 2.05 % Cardio sciences + GI Surgery + Gastro enterology + Pediatric Surgery + Nursery+Cancer = 7.4 %

System existent in the sample hospital: The sterile supply system is mainly centralized in the hospital. The in-patient areas, OPDs and surgery & allied specialty areas receive their sterile supply from the CSSD. The OT's also have smaller units for the purpose of 'FLASH Sterilization'. These smaller units are used only for sterilizing the smaller, single piece instruments, which are required immediately for the on- going surgery. There are a few items in charge of the CSSD, but most of the items are in charge of the respective user areas. The items in charge of CSSD are distributed on "Exchange Cart Distribution" basis and generally include the frequently used items. The items in "Exchange Cart Distribution" are:

  • Cut Down sets
  • Dressing sets
  • Lumbar Puncture sets
  • Bone Marrow Biopsy sets
  • Tracheotomy sets
  • Inter-costal sets
  • Skin Biopsy sets
  • Thoracic Aspirate sets
  • Skull Traction Sets
  • Skalet Aliradine Neuro sets
  • Wash Down sets
  • Liver Biopsy sets
  • Syringes (Glass-15 in number)

In addition to the above, the various general / specialist OT's have their own instruments cleaned, serviced and packed in the OT after the case is over and sent over to the CSSD for sterilization. The supply sent to the CSSD for sterilization is ready for issue, after processing (sterilization), with in 6-8 hours. For all areas other than the OT, the instruments are received by the CSSD in the evening shift of the day and are issued the next day in the morning shift. In case of OT / ICU / Casualty areas, the items are received by the CSSD in all the three shifts and are ready for issue by the next shift. This system has evolved in the hospital as result of rapid turnover of the instruments due to the 24 Hr running of most of the OT's.

Results of two weeks of study: The CSSD has nine autoclaves, which are of pre-vacuum type. (For calculation of total sterilization capacity available, other factors like manpower, continuous water and electricity supply etc were assumed to be optimal)

Open-ended interviews with the user end: The interview indicated that during the period of study, there was no complaint of cancellation of surgery {minor/ major} specifically due to under/non availability of sterile supply from the CSSD. Other areas in the hospital also had no such complaints for the duration of study. Further, there was also no complaint regarding the quality of sterile supply. The biological indicator sample sent to the department of Microbiology during the period of study showed negative sample, indicating properly functioning autoclaves.


The CSSD of the above mentioned hospital, which is a 1846 bedded, tertiary care super-specialty unit, is under utilized at 38.4% {<50 % is considered to be underutilized}.

Utilization Coefficient, which is usually calculated by the number of hours of use had to be modified for the purpose of the study, as, in a steam autoclave, by virtue of its process, the running time of the machine is less than the actual time for which the load is processed. This is so because of time taken for 'breaking of vacuum' and cooling of the load. Keeping these factors in mind an alternative method of calculation of Utilization of the machines was used. This method took into consideration the maximum capacity sterilizable / 24 Hrs and the current capacity used for sterilization! 24 Hrs.

1 Number of 96 cu ft autoclaves = 2 (working){cu ft = cubic feet}
2 Number of 36 cu ft autoclaves = 7 (working)
3 Total available cubic feet= 444 cu ft
4 1 complete cycle time = loading the machine to unloading (after the load has cooled down) = 3 Hrs+/- 15 minutes
5 With a 3 Hr cycle, a machine can run a maximum of 8 times in a 24 Hrs. Therefore, the Total sterilization capacity [TSC] available at presumed 100% utilization is 3552 cu ft. in 24 Hrs.
6 With 10% margin for preventive maintenance, this would put approximately 355.2 cu ft not usable, at any time i.e. 3197 cu ft is the maximum available sterilization capacity per 24 Hrs == Net Sterilization Capacity [NSC]
7 Total load sterilized in the duration of study = 17206, i.e. average of 1229 cu ft volume sterilized per 24 Hrs
8 Hence Utilization of the machines = {capacity utilized per 24 Hrs / Capacity which the CSSD can sterilize in 24 Hrs} (1229/3197) * 100 = 38.4% [with 10 % margin for preventive maintenance]
9 Capacity available per bed in the sample hospital= 3197/1846 = 1.732 cu ft per bed per 24 Hrs
10 Capacity utilized by the hospital under study = 1229/ 1846 = 0.665 cu ft per bed per 24 Hrs

Correlation of the interviews with the currently used capacity of the CSSD, it can be concluded that for a super-specialty teaching hospital the optimal volume of sterilizable space that should be available for avoiding underutilization is 0.665 cu ft per bed in 24 Ms (this is exclusive of the buffer for maintenance) which is the Net Sterilization capacity required. Optimal Total Sterilization Capacity can be estimated to give buffer for maintenance down time. TSC = 0.730 cu ft per bed in 24 Ms.

# For sterilization capacity
[T S C - 10% of T S C = N S C]

Tertiary Care Super Specialty Hospital

Number of
Net Sterilization
required- cu ft
Total Sterilization
required- cu ft
100 66.5 73
500 332.5 365
750 498.75 547.5
1000 650 730
1500 997.5 1095
2000 1330 1460


The planning of a sterilization service in a super-specialty hospital has been, until now based on space required in terms of 'Area of CSSD per bed'. Due consideration has not been given to the case-mix received by the hospital and the workload variations. With the above estimations of 'Volume of space required per bed' for effective and efficient sterilization services, relevant and reliable estimations of the number of autoclaves (of known capacity) is possible. This calculation must be based on the Total sterilization Capacity.


  1. Laforce F M. Control of infections in the Hospitals: 1750- 1950. In. Wenzel R P. Editor; Prevention and Control On Nosocomial Infections;3rd edition; Williams & Wilkins USA, 1997: 3-19
  2. Ducel G, Fabry J, Nicolle L.Editors In. Prevention of Hospital-Acquired infections; 2nd edition WHO, AITBS Publishers Delhi, 2004
  3. Joslyn L. Sterilization by Heat. In. Block S S. Editor ;Disinfection, Sterilization & Preservation; 3rd edition; Lea & Febiger, 1983: 1-46
  4. Kunders G D Editor In. Hospitals:Facility Planning and Management, Tata McGraw Hill New Delhi, 2004: Chapter 9, Planning and Designing Support services 332-396

* Professor. Department of Hospital Administration, AllMS. New Delhi, India
** Resident Administrator, AIIMS, New Delhi, India

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