a number of studies have shown that the severity of hypoxemia is frequently underestimated , even by experienced emergency physicians . with noninvasive methods such as pulse oximetry and capnometry , the ability to obtain reliable measurements assessing oxygenation and ventilation can be limited by abnormal physiologic states commonly seen in emergency patients . in emergency situations ( eg shock , bleeding , during cardiac massage , etc ) an abnormal ventilation / perfusion ( v / q ) relationship affects end tidal co2 ( etco2 ) measurements , and the absence of an adequate pulse signal can result in the failure of pulse oximetry to measure arterial hemoglobin saturation ( spo2 ) . in addition , optimization of the electrolyte status , specifically potassium ( k ) and ionized calcium ( ca ) , is important in the treatment of a developing or manifested cardiac failure . the purpose of this study was to describe our first experiences with the irma blood analysis system ( diametrics , chemomedica - austria , vienna , austria ) , a portable , battery - powered blood analyzer which has been available since april 1996 as part of a prehospital emergency physician system . the emergency system at the university of graz is a combination of stationary and rendezvous components . the stationary component is an emergency patient transport vehicle , operated by four emergency technicians of the austrian red cross . one of these individuals , similar to american paramedics , is a young physician or medical student , at the end of their training , who specialised in emergency medicine . the second component is a small emergency car , carrying the emergency physician and an emergency technician , which transports the doctor to the site of the accident , but which can not transport the patient . consequently , six well educated emergency staff members attend the patient at the site of the accident . firstly , six indications for prehospital blood analysis were defined : 1 . cardiopulmonary resuscitation ( cpr ; blood gases and electrolytes ) ; 2 . all forms of dyspnea or hypoxia ( blood gases ) ; 3 . suspected acidosis ( blood gases and electrolytes ) ; 4 . samples for tests which included blood gas analysis were taken from an artery with a 26 g needle and a heparinized syringe ; samples for electrolytes alone were taken from an artery or vein . additionally , a form was completed by the emergency physician which included the following two questions : 1 . the emergency physician obtained and interpreted the measurements , and performed the resulting therapeutic interventions at the site of the emergency . all emergency doctors were anesthesiologists at the department of anesthesiology and critical care medicine with more than 2 years ' experience in prehospital care . a retrospective investigation of the outcome of the patients and the accuracy of the tentative diagnosis was not performed . the study aimed to evaluate the management and usefulness of a new transportable blood analyzer at the site of an emergency , and the immediate therapeutic consequences . a prerequisite of the study was not to disturb the essential treatment of emergency patients . the irma blood analysis system is one of a new class of instruments which are used for what is termed ` point - of - care testing ' ( poct ) , indicating that it can be used wherever the patient may be to measure blood gases and ph , as well as the electrolytes sodium ( na ) , k and ca . the device consists of the analyzer and two types of cartridge , one labeled ` blood gases ' and the other ` electrolytes ' . each cartridge is prepackaged with a calibration gel covering the sensors , and with a short fluid filled pouch which stabilizes the humidity . the calibration of the sensors takes place automatically when the cartridge is inserted into the irma blood analyzer ; there is no need for calibration gases or fluids . the instrument can only be filled using a syringe , and the blood sample ( minimum = 0.2 ml , maximum = 3.0 ml , recommended amount = 1.5 ml ) must be injected with dosed power into the filling gap of the cartridge . the instrument measures barometric pressure and determines ph , po2 , and pco2 by analyzing the sample in the blood gas analysis ( bga ) cartridge ; additional parameters are also calculated ( see table 1 ) . using the electrolyte cartridge , na , k and ca are determined . the accuracy of the measurements from the irma blood analyzer have been validated in previous studies . the device has the size ( 29.2  24.1  12.7 cm ) and weight ( 1.35 kg ) of a small laptop computer , and each cartridge weighs 19 g and is 9.9  5.6  1.3 cm in size . data entry into the analyzer is performed through a back - lit interactive touch screen . an on - board printer provides a hard copy of results either automatically or on demand . an rs232 port on the back of the unit allows the downloading of data to a personal computer or other data collection system . the price of the irma blood analysis system is approximately ats100,000 ( $ 10,000 ) . each cartridge ( used for one measurement , blood gases or electrolytes ) costs about ats100 ( $ 10 ) . the single - use disposable cartridges can be stored for 12 weeks in normal ambient temperature ( 1230c ) . the system is maintained in stand - by mode , with the power automatically switching on when a cartridge is inserted . after confirmation of this code on the touch screen , the calibration procedure starts automatically . depending on whether an electrolyte or blood gas cartridge is being used the system requires 10 or 90 s to warm up , respectively . the end of the calibration procedure is announced by a beep , after which the user has 120 s to inject the blood sample . finally , the results are shown on the display and can be printed on demand . the entire measurement takes approximately 70 s for electrolytes and 160 s for blood gases . correction of the calibration code , if necessary , requires an additional 25 s. in cases of hypothermia , the blood temperature can be corrected after the measurement and the results recalculated . the irma blood analysis system is one of a new class of instruments which are used for what is termed ` point - of - care testing ' ( poct ) , indicating that it can be used wherever the patient may be to measure blood gases and ph , as well as the electrolytes sodium ( na ) , k and ca . the device consists of the analyzer and two types of cartridge , one labeled ` blood gases ' and the other ` electrolytes ' . each cartridge is prepackaged with a calibration gel covering the sensors , and with a short fluid filled pouch which stabilizes the humidity . the calibration of the sensors takes place automatically when the cartridge is inserted into the irma blood analyzer ; there is no need for calibration gases or fluids . the instrument can only be filled using a syringe , and the blood sample ( minimum = 0.2 ml , maximum = 3.0 ml , recommended amount = 1.5 ml ) must be injected with dosed power into the filling gap of the cartridge . the instrument measures barometric pressure and determines ph , po2 , and pco2 by analyzing the sample in the blood gas analysis ( bga ) cartridge ; additional parameters are also calculated ( see table 1 ) . the accuracy of the measurements from the irma blood analyzer have been validated in previous studies . the device has the size ( 29.2  24.1  12.7 cm ) and weight ( 1.35 kg ) of a small laptop computer , and each cartridge weighs 19 g and is 9.9  5.6  1.3 cm in size . data entry into the analyzer is performed through a back - lit interactive touch screen . an on - board printer provides a hard copy of results either automatically or on demand . an rs232 port on the back of the unit allows the downloading of data to a personal computer or other data collection system . the price of the irma blood analysis system is approximately ats100,000 ( $ 10,000 ) . each cartridge ( used for one measurement , blood gases or electrolytes ) costs about ats100 ( $ 10 ) . the single - use disposable cartridges can be stored for 12 weeks in normal ambient temperature ( 1230c ) . the system is maintained in stand - by mode , with the power automatically switching on when a cartridge is inserted . after confirmation of this code on the touch screen , the calibration procedure starts automatically . depending on whether an electrolyte or blood gas cartridge is being used the system requires 10 or 90 s to warm up , respectively . the end of the calibration procedure is announced by a beep , after which the user has 120 s to inject the blood sample . finally , the results are shown on the display and can be printed on demand . the entire measurement takes approximately 70 s for electrolytes and 160 s for blood gases . correction of the calibration code , if necessary , requires an additional 25 s. in cases of hypothermia , the blood temperature can be corrected after the measurement and the results recalculated . during the observation period ( april to september 1996 ) 32 analyses were attempted on 25 patients . eleven of these samples could not be measured due to problems with the individual cartridges -- two were damaged , and nine had to be replaced and the procedure repeated due to the analyzer indicating a ` cartridge - error ' . the indications for blood analysis , the measured parameters , and the diagnostic and therapeutic consequences are listed in table 2 . in 18 of the 25 cases the measurements were helpful for diagnosis , and resulted in therapeutic consequences in 13 patients . in many cases knowledge of electrolyte or blood gas parameters was helpful , but indicated that no therapy was needed . after a short training session the operation of the device was problem free , and the results seemed reliable . because the data collection period was during the summer the effect of low ambient temperature could not be evaluated . this new transportable blood analyzer , the irma blood analysis system , opens up important opportunities in prehospital emergency care . many therapeutic strategies in the treatment of severe life threatening situations depend on the knowledge of blood parameters . in ` standards and guidelines for emergency care ' the american heart association recommends the following application of sodium bicarbonate during cpr , based on blood gas concentrations or levels of serum potassium : class i in the presence of hyperkalemia ; class iia with metabolic acidosis ; class iib in cases of a long arrest interval or after return of spontaneous circulation , and class iii with hypoxic lactate acidosis . according to these recommendations we were able to apply sodium bicarbonate exactly on demand . an analysis of the therapeutic benefits and patient outcomes was not possible because we had only three patients requiring cpr and only two of them needed buffering . without prehospital measurements the determination of the potential benefits or risks of the application of ca   would not have been possible in these patient care situations . although ca is essential for myocardial contraction , its blind application during cardiac failure is not recommended because of the inherent risk of hypercalcemia which could result in an irreversible myocardial contraction ( class iii ) . based on our findings this blood analyzer allows much better prehospital management of cardiac failure or cpr by providing the necessary data in a rapid , reliable and easy to use manner . during the observation period the irma blood analyzer used in this study provides additional measurements to the opti 1 ( avl , graz , austria ) , an alternative prehospital system which at present only determines blood gases . the third available system , i - stat ( hewlett packard , vienna , austria ) , measures blood gases , electrolytes , and also the hematokrit . techniques are already in use which are somewhat helpful in detecting hypoxia or breathing status -- transcutaneous po2 measurement and pulse oximetry . in the prehospital setting only pulse oximetry is commonly utilized . pulse oximetry measures oxygen saturation noninvasively at the finger or earlobe and , therefore , requires a sufficient pulse wave . furthermore , acute carbon monoxide ( co ) poisoning constitutes a particular problem as , in this situation , many pulse oximeters report overestimated oxygenation results which wrongly indicate adequate oxygen saturation and are , therefore , useless . carbon monoxide - induced hypoxemia is caused by the presence of co bound to hemoglobin . therefore , the patient may suffer from severe hypoxia while pulse oximetry and arterial po2 measurements fail to reflect the critical situation . since the irma blood analyzer does not detect partial oxygen saturation , co poisoning does not cause it to overestimate oxygen content . additionally , severe peripheral hypoxia also leads to lactate production and reduces ph , a parameter which can be determined by blood gas analysis . recent studies have described the importance of meticulously performed mild hyperventilation in severe head injury . capnometry measures etco2 and is a valuable instrument for the estimation of patients ' breathing or ventilation status if v / q is not severely deranged . in situations of severe cardiovascular insufficiency and cpr , capnometry can either fail or significantly underestimate arterial pco2 . lung contusions or aspiration result in atelectasis and an altered v / q ratio . cardiovascular insufficiency , like shock or cpr , leads to dead space ventilation ; the lungs are ventilated , but insufficiently perfused . in the critically ill patient , optimal oxygenation , mild hyperventilation and adequate therapy can not be performed without blood gas analysis . however , the routine use of the irma system revealed several problems : 1 . the system showed a high failure rate ( 34% ) , mainly due to problems with cartridge calibration . it may be possible that , due to the difficult storage procedures , the calibration gel spoiled , although the storage time had not been exceeded . another cause of problems was a batch of inoperable cartridges ; these cartridges were changed by the company within a few days . the system can only be filled with a syringe and a dosed pressure has to be applied . this means that , for blood gas analysis , arterial puncture or arterial access is necessary as the system has not yet been designed for withdrawal of blood from capillaries . in cases of insufficient blood quantity or excessive application pressure , contrary to the manufacturer 's specification of a minimum sample amount of 0.2 ml , our experiences suggest that at least 1.5 ml of blood are required to obtain a valid measurement . 3 . for emergency systems with lower numbers of calls , the limited life span ( 12 weeks ) of the cartridges could result in wastage . an on - demand controlled ordering system would be an easy solution to this potential problem . the touch screen is arranged in alphabetical order rather than as a common keyboard and , therefore , requires familiarization by users . entering the calibration code is , therefore , too time consuming ( 25 s per attempt ) . there are several indications for the use of prehospital blood analysis in emergency situations . in cases of critically ill or severely traumatized patients the widely used monitoring techniques like pulse oximetry and capnometry are limited and not acceptable alternatives to blood gas analysis . the irma transportable blood analyzer , which has been available since april 1996 , can deliver these valuable blood gas measurements . the system has been found to be very useful ; it is easily transportable and after some corrections performs reliably . we believe that in the future prehospital blood analysis will become an important part of a well organized emergency system . measured and calculated parameters list of patients , diagnoses , results and the therapeutic consequences m = male ; f = female ; cpr = cardiopulmonary resuscitation .
background : this study evaluated the feasibility of blood gas analysis and electrolyte measurements during emergency transport prior to hospital admission.results:a portable , battery - powered blood analyzer was used on patients in life threatening conditions to determine ph , pco2 , po2 , sodium , potassium and ionized calcium . 
 arterial blood was used for blood gas analysis and electrolyte measurements . 
 venous blood was used for electrolyte measurement alone . during the observation period of 4 months 
 , 32 analyses were attempted on 25 patients . 
 eleven measurements ( 34% ) could not be performed due to technical failure . 
 overall , 25 samples taken from 21 patients were evaluated . 
 the emergency physicians ( all anesthesiologists ) considered the knowledge of blood gases and/or electrolytes to be helpful in 72% of cases . 
 this knowledge led to immediate therapeutic consequences in 52% of all cases . 
 after a short training and familiarization session the handling of the device was found to be problem free.conclusions:we concluded that knowledge of the patients ' ph , pco2 and po2 in life threatening situations yields more objective information about oxygenation , carbon dioxide and acid - base regulation than pulse oximetry and/or capnometry alone . additionally , it enables physicians to correct severe hypokalemia or hypocalcemia in cases of cardiac failure or malignant arrhythmia .