Inhalational anaesthesia in developing countries. Part I. The problems and a proposed solution

Bridging the mismatch: observing the introduction of new anesthesia technology for a low-resource environment

Objective

The objective of this study was to examine the impact of the introduction of the Universal Anaesthesia Machine (UAM), a device designed for use in clinical environments with limited clinical perioperative resources, on the choice of general anesthesia technique and safe anesthesia practice in a tertiary-care hospital in Sierra Leone.

Methods

We introduced an anesthesia machine (UAM) into Connaught Hospital, Freetown, Sierra Leone. We conducted a prospective observational study of anesthesia practice and an examination of perioperative clinical parameters among surgical patients at the hospital to determine the usability of the device, its impact on anesthesia capacity, and changes in general anesthesia technique.

Findings

We observed a shift from the use of ketamine total intravenous anesthesia to inhalational anesthesia. This shift was most demonstrable in anesthesia care for appendectomies and surgical wound management. In 10 of 17 power outages that occurred during inhalational general anesthesia, anesthesia delivery was uninterrupted because inhalational anesthesia was being delivered with the UAM.

Conclusion

Anesthesia technologies tailored to overcome austere environmental conditions can support the delivery of safe anesthesia care while maintaining fidelity to recommended international anesthesia practice standards.

Neonatal anesthesia with limited resources

Neonates are the most vulnerable age group in terms of anesthetic risk and perioperative mortality, especially in the developing world. Prematurity, malnutrition, delays in presentation, and sepsis contribute to this risk. Lack of healthcare workers, poorly maintained equipment, limited drug supplies, absence of postoperative intensive care, unreliable water supplies, or electricity are further contributory factors. Trained anesthesiologists with the skills required for pediatric and neonatal anesthesia as well as basic monitoring equipment such as pulse oximetry will go a long way to improve the unacceptably high anesthetic mortality.

The Glostavent: Evolution of an Anaesthetic Machine for Developing Countries

The sophisticated anaesthetic machines designed for use in modern hospitals are not appropriate for many parts of the developing world, as they are reliant on regular servicing by skilled engineers and an uninterrupted supply of electricity and compressed gases, which are not always available. The Glostavent has been designed specifically to meet the challenges faced by anaesthetists working in these countries. It is robust, simple to use, economical, easy to service and will continue to run during an interruption of the supply of oxygen or electricity. Feedback from widespread use throughout the developing world over the last 10 years has led to significant improvements to the original design. This article describes the basic components of the original version and the modifications which have been introduced as a result of practical experience in the developing world.

FIELD USE OF ISOFLURANE AND AIR ANESTHETIC EQUIPMENT IN WILDLIFE

Conventional inhalation anesthesia of wildlife species within natural habitats presents significant practical problems. Heavy cylinders of medical grade oxygen are often unavailable in field situations. Equipment has been modified to permit the delivery of isoflurane in ambient air as the carrier and to be fitted with circuitry adaptable for different species and anesthetic situations. Preliminary empirical studies at low altitude in a range of small mammalian and avian species demonstrate the suitability of this combination and these techniques for inducing and maintaining anesthesia in clinically normal patients undergoing relatively minor procedures. The equipment has also been used to deepen and prolong anesthesia in several larger species, including great apes and large cats, after induction with injectable agents. These techniques, in combination with pulse oximetry to detect hypoxemia, provide a cheap, robust, and portable inhalation anesthetic system for field situations that is not dependent on compressed gasses.

Anaesthesia in rural Tanzania

A survey of the anaesthetic services in rural Tanzania was carried out in an area of 67500 km2 and population of 4 million in order to assess the quality of anaesthesia and the major obstacles to good practice. Lack of draw-over vaporizers, Ayre's T-pieces, and a supply of oxygen were found to be the major obstacles to safe practice in this area of Africa.

A method for assessment of standards of care of anesthesia services in departments with different levels of resources

In developing countries the standards of anesthesia care vary greatly between hospitals. In order to identify the urgent needs of disadvantaged hospitals, we compared three index hospitals in the greater Cairo area, one of which has excellent (category I), on intermediate (category II), and one with severely restricted resources (category III). Standards of care published by the American Society of Anesthesiologists (ASA) were used to develop a spreadsheet for documenting features of pre-, intra- and post-anesthetic care in patients undergoing tonsillectomies, a procedure commonly performed in all three hospitals. The spreadsheet enabled us to document all equipment, supplies and personnel engaged from pre-anesthetic evaluation to discharge. Analysis of the data revealed that the service provided by the category I hospital approached the ASA standards. In the category II hospital the patients did not go through a pre-anesthetic evaluation; instead they were seen for the first time in the operating room. No premedication was given. Intravenous access was established with the help of a needle (rather than a catheter). Monitoring consisted occasionally of a finger on the pulse. Sterilization was accomplished by boiling. Air-conditioning was not available. No records were kept and no recovery room was available. The same deficiencies existed in the category III hospital, which did not even have oropharyngeal airways, antiarrhythmic or inotropic medications, and sterile techniques were completely ignored. Despite these stark differences in care, the patients or their parents in all three hospitals appeared satisfied with the level of care they received. Much has to be done to improve anesthesia care in less fortunate departments in developing nations. Urgent help does not mean the need for sophisticated monitors or equipment only, but the establishment of practice standards first. Applying the priciples of modern management, we need to evaluate the structure, processes and outcome of anesthetic practice in developing countries in order to reengineer the way we provide help to anesthetic departments in developing nations. In this modest study we are presenting a means to evaluate the features and processes of the anesthesia services in developing countries.

An evaluation of the Universal PAC and Oxford Miniature Vaporizers for paediatric field anaesthesia

A laboratory study has demonstrated that the Universal PAC and Oxford Miniature Vaporizers can be used for paediatric anaesthesia in drawover mode at varying ambient temperatures. Changes in tidal volume have minimal effect on the delivered concentration of halothane from either vaporizer but varying ambient temperature significantly affects the output of the Oxford Miniature Vaporizer. The Oxford performs well in continuous flow mode, which is of particular use for T-piece anaesthesia, whereas the Universal PAC does not perform adequately in this way.

Fresh gas flow and carbon dioxide rebreathing in a low pressure semi-open anaesthesia system

We have constructed a simple system for field anaesthesia by using a Farman entrainer and a semi-open circuit to convert a draw-over apparatus to a continuous flow air/O2 system. Compressed O2 was the driving gas for the entrainer; fresh gas (FG) delivered to the semi-open circuit was a mixture of O2, entrained air and anaesthetic vapour. The purpose of this study was to examine FG flow rate and CO2 rebreathing during intermittent positive pressure ventilation (IPPV). A non-rebreathing inflation valve (Laerdal) placed at the end of the expiratory (efferent) limb of the circuit vented both expiratory gas and excess FG. Ambient air IPPV was applied through the Laerdal valve from a self-inflating bag or ventilator. Since this circuit is functionally similar to a T-piece, the gas from the efferent limb (340 ml, containing FG) entered the lungs first. If tidal volume was larger than 340 ml the balance was ambient air. Minute ventilation of the lungs with efferent limb gas was defined as Veff. Respiratory gas was sampled at the endotracheal tube and the CO2 tension was measured with a NIHON-KOHDEN CO2 analyzer. Thirty-seven adult patients having intra-abdominal or pelvic surgery under general tracheal anaesthesia were studied. Four FG flow rates (5.7, 8.0, 9.3, and 10.4 L.min-1), corresponding to driving gas pressures of 40, 60, 80, and 100 mmHg, were introduced in random order. Although inspired CO2 was detected at FG flow rates of 5.7-9.3 L.min-1, there were no differences in PETCO2 among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The Johannesburg Hospital mobile anaesthesia service

At a teaching hospital such as the Johannesburg Hospital with an air ambulance service, the need may arise for the administration of an anaesthetic outside the hospital. The occurrence of just such an event prompted the authors to review the literature regarding anaesthesia in adverse circumstances and to assemble, in a portable container, the equipment and drugs considered necessary to cope with the situation. In addition, the responsible anaesthetic personnel are receiving training in the use of the equipment and techniques required.

Central circulation during halothane-diethyl-ether azeotrope and isoflurane anaesthesia in the pig

The fatal anaesthetic ratio (FAR) has been determined for halothane-diethyl-ether (HE) in pigs, and the central circulation during hypovolaemia has been investigated using a well-documented agent such as isoflurane as a standard. The fatal anaesthetic ratio for HE in pigs was (3.21/1.03) = 3.12. This is high compared to the FAR for halothane of 1.7. The central circulation was investigated in 12 pigs which were randomly allocated to either HE or isoflurance anaesthesia, respectively. Baseline values were recorded when they were stable at 1.3 MAC of the volatile anaesthetic used. The pigs were bled 30% of their blood volume, and measurements were made at 5 and 30 min. There was one significant difference between these groups in central circulation: the blood pressure was higher at baseline measurement in the HE group. At 5 min and 30 min, there were no significant differences between these groups. There was a general depression of central circulation without any sign of decreased contractility. HE anaesthesia is well tolerated during hypovolaemia in pigs.

Minimum alveolar concentration of halothane-diethyl-ether azeotrope

The azeotropic mixture of halothane and diethyl ether (HE) may be a valuable alternative to other anaesthetic agents under circumstances such as war, civil disaster, and primitive conditions. In the present study the minimum alveolar concentrations (MACs) for HE in man (n = 25) and in pigs (n = 6) were determined. For comparison with results of other studies, the MAC for halothane in man (n = 14) was also determined. A Normac gas analyser and a Varian 3700 gas chromatograph were calibrated against known standards of HE. The performance of two vaporizers (Fluotec Mark III, Servo vaporizer for halothane) was studied. The Fluotec Mark III vaporizer and the Servo halothane vaporizer filled with HE gave a linear performance with increasing dial settings. The Normac gas analyser set for methoxyflurane was linearly sensitive to the ether component of the azeotrope. The MAC for HE in man was 0.71 vol.% +/- 0.03 (s.e.mean) (ether 0.21 vol.%, halothane 0.50 vol.%) in the age group 19-42 years. MAC for halothane in man was 0.65 +/- 0.03 in the age group 19-32 years. The MAC for HE in pigs between 20-24 kg was 0.99 vol.% +/- 0.07. The ether component seems to act synergistically with halothane in the azeotropic mixture. The present study provides an opportunity to compare HE with other volatile anaesthetic agents.

Re-evaluation of the Farman entrainer in a low-pressure system for field anaesthesia

The aim of this project was to develop a portable anaesthesia system that was compatible with modern anaesthesia practice under field conditions, when compressed gas supplies are limited. We assembled and evaluated a low-pressure plenum system, based upon the Farman entrainer, which was adaptable to spontaneous, assisted or intermittent positive pressure ventilation (IPPV). The entrainer was tested using a low flow of compressed gas, O2 at 1-3 L.min-1. We measured the fresh gas flow (FGF) and O2 concentrations (F1O2) delivered at various source gas flow rates (O2 flow), and with various breathing circuits. Entrainment ratio, FGF, and F1O2 were highly dependent upon resistance to flow in the different breathing circuits. With a wide bore T-piece the air/O2 entrainment ratio was 6:1, and the F1O2 was 0.3. When circuit resistance was higher, e.g., with the Bain circuit, air entrainment and FGF were reduced, but F1O2 was higher. Because it offered the lowest resistance, the T-piece circuit was selected for a clinical trial.

A low-pressure portable anaesthesia system for field use: clinical trials

This is a report of our experience with a portable anaesthesia system that was developed for use under field conditions, when compressed gas supplies are limited. We first assembled and bench-tested a low-pressure plenum system, based upon the Farman entrainer. The entrainer required a low flow of compressed gas, O2 at 1-2 L.min-1, and generated a low-pressure mixture of O2 and air which was directed through an Oxford miniature vaporizer, a non-return valve, and a widebore T-piece circuit. With this system we anaesthetized 24 patients with intermittent positive pressure ventilation (IPPV) and nine patients breathing spontaneously. During IPPV, the circuit resembled a T-piece and provided effective gas exchange with a FGF of 1.2 times minute ventilation. Inspiratory and expiratory valves were arranged so that the spontaneous mode was non-rebreathing, and FGF was adjusted to equal minute ventilation. The system was very economical, using 1-2 L.min-1 O2 and 20-25 ml.hr-1 liquid halothane to produce a FGF of 6-10 L.min-1, an FIO2 of 0.33, and FIhal of 1-1.5 per cent. We have demonstrated that this is a versatile, safe, and economical system, compatible with the practice of modern inhalational anaesthesia under field conditions. It can be readily assembled from commercially available components.

Paediatric anaesthesia in a developing country

A suitable anaesthetic technique was needed for oral surgery in infants in a developing country. As an air compressor was present, and oxygen accessible, a continuous flow technique was chosen. Two Boyle's machines--useless due to lack of soda lime and nitrous oxide--were converted without increasing susceptibility to technical and supplemental deficiencies. The challenge to simplify techniques without reducing patient safety is discussed, and the solutions in an Ethiopian hospital are presented.

The Malawi anaesthetic machine. Experience with a new type of anaesthetic apparatus for developing countries

One year's experience with a new type of oxygen concentrator and anaesthetic machine, designed for anaesthesia in developing countries, is presented. The apparatus, its performance and problems are described and the author's suggested modifications to improve the original design are outlined. The apparatus, with these changes, represents a significant advance in oxygen availability for hospitals in developing countries as well as improving the anaesthetic capabilities.

A drawover Boyle's machine. Development and evaluation in Zambia

A standard Boyle International anaesthetic machine was modified to allow operation in either a continuous flow or a drawover mode. This was achieved by fitting a valve in the backbar which allows entrainment of air under drawover conditions. The details of the valve and modification are discussed and an evaluation of the machine in a Central African hospital is presented.

A combined oxygen concentrator and compressed air unit. Assessment of a prototype and discussion of its potential applications

A prototype combined oxygen concentrator and air compressor is described. Laboratory assessment demonstrated satisfactory oxygen concentrations, flows, pressures and reliability. Its various modes of use in clinical practice are described. It is likely to be a valuable method to provide oxygen for anaesthesia both in remote areas and where nitrous oxide-free anaesthesia is required, as well as a reliable alternative to commercially produced oxygen for therapeutic purposes.

A comparison of halothane and trichloroethylene with isoflurane. A study of drawover air anaesthesia with the Triservice anaesthetic apparatus

Induction and recovery times were not significantly different between two groups that received halothane with trichloroethylene and isoflurane, respectively. Maintenance of anaesthesia and analgesia was also satisfactory. Isoflurane resulted in a higher heart rate (p less than 0.01), a lower respiratory rate (p less than 0.01) and a higher inspired oxygen concentration (p less than 0.05). Respiration may be more efficient. Other potential advantages of isoflurane for anaesthesia in the field are discussed. Despite the fact that it is 15 times more expensive, the use of isoflurane as sole agent is recommended.

Anaesthesia training in Nepal

The background, organization, problems, and successful implementation of an anaesthesia training program in Nepal are described. Nepali physicians had previously taken their postgraduate anaesthesia training in western countries, especially in Britain. The low pay of anaesthetists, poor maintenance of equipment, and irregular supplies of anaesthetic drugs in their own country has led many of them to stay abroad. In 1985 there were only seven Nepali anaesthetists in Nepal for a population of 16 million. An alternative approach to training is presented in which a series of Canadian anaesthetists, over a three-year period, are supporting the establishment of a one-year Diploma in Anaesthesiology program in Nepal. They are working with Nepali anaesthetists and the Institute of Medicine in Kathmandu, Nepal. The local anaesthetists supervise most of the clinical training while the Canadians give academic leadership and guidance.

The 'Mini O2' and 'Healthdyne' oxygen concentrators. Their performance and potential application

Two oxygen concentrators designed for home use, the 'Healthdyne' and the 'Mini O2', have been assessed with particular reference to their possible role in anaesthesia. Both were found to be a reliable source of oxygen enriched gas. Neither was fully capable of driving a gas powered ventilator satisfactorily, but both could potentially be very useful in normal and field anaesthetic practice.

Inhalational anaesthesia in developing countries. Part II. Review of existing apparatus

We have reviewed the availability of apparatus which permits the maximum use to be made of available supplies and services in developing countries. In particular we have stressed the use of electrically operated air compressors and oxygen concentrators to drive sophisticated anaesthetic apparatus which is not dependent on supplies of compressed gases in cylinders.