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Effect of intra-aortic occlusion balloon in external thoracic compressions during CPR in pigs.

This study was performed to compare the effectiveness of external thoracic compressions with and without intra-aortic occlusion balloon with capnography and coronary and cerebral perfusion pressure (CPP) in the normothermic and traumatic-less cardiopulmonary arrest provoked by a ventricular fibrillation in pigs. This was an experimental study (cross-over study) in 14 pigs with similar characteristics (23 +/- 2 kg, 10-12 weeks of age). After an 8-minute nonintervention period, the cardiopulmonary resuscitation (CPR) consists of 4 periods of 5 minutes alternating CPR with and without intra-aortic occlusion balloon. Main outcomes measured are end-tidal CO(2) (ETCO(2)); intra-aortic, coronary, and cerebral perfusion pressures; blood gas analysis; and blood lactate concentration. At the end of each period, levels are obtained. Postmortem study was made. Inflation of the occlusion balloon provokes an expansion in the ETCO(2) of about 38%. The coronary perfusion pressure initially goes from 10.21 to 29.0 mm Hg after the occlusion of the aorta, which means an increase of 150%. The CPP goes from 12.54 to 39.71 mm Hg after the balloon was inflated, which means an increase of 200%. In all cases the differences are statistically significant (P <.0001). These increases are less important in the final periods. Intra-aortic balloon occlusion increased ETCO(2), coronary, and cerebral perfusion pressures. An early application of this technique was important.

Animals↗

[Simultaneous measurements of end-expiratory and transcutaneous carbon dioxide partial pressure in ventilated premature and newborn infants].

BACKGROUND: The aim of the present trial was to study the relationship between end-tidal pCO2 (p(et)CO2) and transcutaneous pCO2 (ptcCO2) after in-vivo calibration in ventilated newborns. PATIENTS: 61 end-tidal and transcutaneous pCO2 measurements were simultaneously performed in 30 ventilated preterm and term newborn infants (weight at birth 1862.6 +/- 981.9 g). METHOD: End-tidal pCO2 was measured in mainstream mode at the end of the endotracheal tubus (Novametrix 7000 Medical Systems Inc., USA, dead volume of the chamber 0.6 ml). Transcutaneous pCO2 was measured by means of a Servomed (SMK 365 Hellige, FRG) analyser. RESULTS: The statistical analysis demonstrated a good correlation (r = 0.72, p < 0.001) between ptcCO2 (mean +/- SD, 44.3 +/- 11.2 mmHg) and p(et)CO2 (32.4 +/- 10.4 mmHg). A considerable difference between transcutaneous and end-tidal pCO2 values was observed (p(tc-et)CO2 = +11.9 +/- 8.7 mmHg). This phenomenon was probably caused by ventilation-perfusion disturbances in the studied critically ill neonates. The statistical analysis revealed that the absolute magnitude of the P(tc-et)CO2 difference was independent from disease, episodes of spontaneous respiration or of respiratory frequency. CONCLUSIONS: Capnographic determination of P(et)CO2 provides informations about alveolar ventilation-perfusion-disturbances. Capnography enables the on-line control of end-tidal pCO2 in neonates with respiratory failure. It cannot replace transcutaneous pCO2 measurements or blood gas analysis but it can reduce its frequency in clinically stable patients. The analysis of the capnogram can be used to optimise artificial ventilation. A quantitative evaluation of the capnogram by calculation of Murányi's-CO2-Index was possible only in 28% of the ventilated newborns which limits its value in such patients.

Birth Weight↗

Sidestream end-tidal capnometry as related to infant's position and maturation.

UNLABELLED: The objective of this study was to investigate the effect of body position on sidestream, end-tidal carbon dioxide (EtCO2) wave measurements in maturing infants. Sidestream EtCO2 wave patterns were analysed longitudinally in 20 preterm infants (born at > or = 32 wk) at 32-37 wk gestation, and in 39 full-term controls. Capnography measurements included maximal EtCO2, inspired CO2 and frequency of apnoea events (>3 s) in the supine, supine with inclination, side and prone positions. Apnoea frequency decreased during maturation, and was less prevalent in the prone than in the supine and side positions in preterm as well as in term infants (p < 0.05). No clinically significant apnoea episodes were found in our cohort. EtCO2 in term infants was lower than that in preterm infants (p < 0.05) and was not affected by sleep position in the most premature (<33 wk) and in term infants (>36 wk). EtCO2 was higher in the prone position than in supine or side positions in infants between 33 and 35 wk gestation (p < 0.01). CONCLUSION: Short apnoeic episodes decrease during maturation, and are less prevalent in the prone position in maturing infants (32-37 wk). Only modest changes in EtCO2 were recorded in the different positions during maturation.

Birth Weight↗

Prehospital use of succinylcholine: a 20-year review.

OBJECTIVE: To determine the safety and efficacy of succinylcholine, as an adjunct to endotracheal intubation, administered by paramedics trained in its use. METHODS: Retrospective review of 1,657 consecutive patients, aged 16 years or older, receiving prehospital succinylcholine administered by paramedics. In this community of 175,000 people, trained paramedics intubated both medical and trauma patients with the assistance of succinylcholine. Main outcomes measured were success of intubations, complications of the procedure and/or the drug, and use of alternative methods of airway management. RESULTS: Paramedics successfully intubated 95.5% (1,582) of all patients receiving succinylcholine, 94% (1,045) of trauma patients, and 98% (538) of medical patients. They were unable to intubate 4.5% (74) of the patients. All of these were successfully managed by alternative methods. Unrecognized esophageal intubation occurred in six (0.3%) patients. The addition of capnography and a tube aspiration device, in 1990, decreased the incidence of esophageal intubations. CONCLUSION: Paramedics trained to use succinylcholine, to assist the process of endotracheal intubation, can safely intubate a high percentage of patients.

Capnography↗

Carbon dioxide spirogram (but not capnogram) detects leaking inspiratory valve in a circle circuit.

UNLABELLED: Expiratory valve incompetence in the circle circuit is diagnosed by using capnography (PCO2 versus time) when significant CO2 is present throughout inspiration. However, inspiratory valve incompetence will allow CO2-containing expirate to reverse flow into the inspiratory limb. CO2 rebreathing occurs early during the next inspiration, generating a short extension of the alveolar plateau and decreased inspiratory downslope of the capnogram, which may be indistinguishable from normal. We hypothesized that CO2 spirography (PCO2 versus volume) would correctly measure inspired CO2 volume (VCO2) during inspiratory valve leak. Accordingly, a metabolic chamber (alcohol combustion) was connected to a lung simulator, which was mechanically ventilated through a standard anesthesia circle circuit. By multiplying and integrating airway flow and PCO2, overall, expired, and inspired VCO2 (VCO2,br = VCO2,E - VCO2,I) were measured. When the inspiratory valve was compromised (by placing a wire between the valve seat and diaphragm), VCO2,I increased from 2.7 +/- 1.7 to 5.7 +/- 0.2 mL (P < 0.05), as measured by using CO2 spirography. In contrast, the capnogram demonstrated only an imperceptible lengthening of the alveolar plateau and did not measure VCO2,I. To maintain effective alveolar ventilation and CO2 elimination, increased VCO2,I requires a larger tidal volume, which could result in pulmonary barotrauma, decreased cardiac output, and increased intracranial pressure. IMPLICATIONS: Circle circuit inspiratory valve leak will allow CO2-containing expirate to reverse flow into the inspiratory limb, with subsequent rebreathing during the next inspiration. This CO2 rebreathing causes imperceptible lengthening of the alveolar plateau of the capnogram and is detected only by using the CO2 spirogram (PCO2 versus volume).

Anesthesia, Closed-Circuit↗

Dynamic cerebral autoregulation during sevoflurane anesthesia: a comparison with isoflurane.

UNLABELLED: We investigated dynamic cerebral pressure autoregulation awake and during 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or isoflurane anesthesia in 16 patients undergoing nonintracranial neurosurgical procedures. All patients received a standardized anesthetic, and their lungs were ventilated with 1.5 MAC volatile anesthetic in 100% oxygen to normocapnia. Routine monitors included electrocardiogram, pulse oximetry, end-tidal capnography, and continuous noninvasive blood pressure. In addition, middle cerebral artery blood velocity (Vmca) was measured continuously using transcranial Doppler ultrasonography. Dynamic cerebral autoregulation was tested by inducing a rapid transient decrease in mean arterial pressure by deflation of large thigh cuffs, which were placed around both thighs and inflated to 100 mm Hg above systolic pressure. The Vmca response to the decrease in blood pressure was fitted to a series of curves to determine the rate of dynamic cerebral autoregulation (dRoR). Awake dRoR values were similar in the isoflurane and sevoflurane groups, 32 +/- 2%/s and 29 +/- 2%/s, respectively. dRoR decreased to 5 +/- 1%/s during isoflurane anesthesia but to only 24 +/- 2%/s during sevoflurane anesthesia. We conclude that dynamic cerebral autoregulation is better preserved during sevoflurane than isoflurane anesthesia in humans. IMPLICATIONS: We investigated the effect of sevoflurane and isoflurane on dynamic cerebral pressure autoregulation using transcranial Doppler ultrasonography. At 1.5 minimum alveolar anesthetic concentration, dynamic autoregulation was better preserved during sevoflurane than isoflurane anesthesia.

Adult↗

Defining segments and phases of a time capnogram.

UNLABELLED: The division of a time capnogram into inspiratory and expiratory segments is arbitrary and results in the inability of a time capnogram to detect rebreathing instantaneously. Demarcation of a time capnogram into inspiratory and expiratory components using gas flow signals will not only facilitate prompt detection of rebreathing, but will also allow application of standardized and physiologically appropriate nomenclature for better understanding and interpretation of time capnograms. A Novametrix((R)) CO(2)-SMO plus respiratory profile monitor (Novametrix Medical Systems, Wallingford, CT) was used to obtain a simultaneous display of CO(2) and respiratory flow waveforms on a computer screen during spontaneous and controlled ventilation using a circle system with the inspiratory valve competent (no rebreathing) and with the valve displaced (rebreathing). Because the response time of the CO(2) analyzer was similar to the response time of the flow sensor, a comparison was made between the two waveforms to determine the inspiratory segment (Phase 0) and the expiratory segment of the time capnogram and its subdivisions (Phases I, II, and III). The end of expiration almost coincides with the downslope of the CO(2) waveform in the capnograms when there is no rebreathing. However, in the presence of rebreathing, the alveolar plateau is prolonged and includes a part of inspiration (Phase 0), in addition to the expiratory alveolar plateau (Phase III). IMPLICATIONS: Presently, the division of a time capnogram into inspiratory and expiratory segments is arbitrary. Demarcation of a time capnogram into various components using the gas flow signals facilitates prompt detection of the cause of abnormal capnograms that can widen the scope of future clinical applications of time capnography.

Anesthesia, Closed-Circuit↗

Utility of deadspace and capnometry measurements in determination of surfactant efficacy in surfactant-depleted lungs.

OBJECTIVE: To investigate if bronchoalveolar lavage leads to increased alveolar and physiologic deadspace or a deadspace/ tidal volume ratio and if surfactant replacement restores the lung to its prelavage condition. DESIGN: Prospective, animal cohort study. SETTING: An animal laboratory in a university medical center. SUBJECTS: Seven adult rabbits receiving artificial ventilation. METHODS: Our single-breath CO2 analysis station contained the following equipment: pneumotachometer Ventrak 1550, a mainstream capnometer Capnogard 1265, a signal processor, and computer software. Repeated bronchoalveolar lavage was performed in seven adult rabbits to simulate acute respiratory distress syndrome. Surfactant therapy was administered after bronchoalveolar lavage induced a 20% reduction in baseline arterial PO2. The calculated parameters of alveolar and physiologic deadspace and the deadspace/tidal volume ratio were derived from the single-breath CO2 plot by Ventrak 1550 in combination with the Capnogard 1265. The arterial end-tidal Pco2 difference, the alveolar-arterial PO2 difference, and the arterial/alveolar PO2 ratio were obtained by capnography and arterial blood gas analysis. Measurements of these parameters were performed before bronchoalveolar lavage, during bronchoalveolar lavage, and after surfactant application. MEASUREMENTS AND MAIN RESULTS: The alveolar and physiologic deadspace and the deadspace/tidal volume ratio were significantly higher in lavaged animals. After application of natural surfactant, these parameters were significantly reduced but the baseline values could not be reached. Bronchoalveolar lavage led to a significant fall in the arterial/alveolar PO2 ratio, which increased after surfactant therapy. There was a negative correlation between the arterial/alveolar PO2 ratio and the deadspace/tidal volume ratio. The alveolar and physiologic deadspace and the deadspace/tidal volume ratio correlated with the arterial end-tidal Pco2 difference. The best correlation was obtained between the arterial end-tidal Pco2 difference and the alveolar deadspace/tidal volume ratio (r = 0.98). CONCLUSIONS: Bronchoalveolar lavage elevates the alveolar and physiologic deadspace and the deadspace/tidal volume ratios and is combined with a fall in the arterial/alveolar PO2 ratio. Surfactant treatment improves the gas exchange but does not restore the lung to its prebronchoalveolar lavage condition, which indicates that the exogenous surfactant affects only partly the recruitment of the atelectatic areas.

Animals↗

Report on the development of a procedure to prevent placement of feeding tubes into the lungs using end-tidal CO2 measurements.

OBJECTIVE: To determine the accuracy of a technique using capnography to prevent inadvertent placement of small-bore feeding tubes and Salem sump tubes into the lungs. SETTING: Twelve-bed medical intensive care unit (MICU) in a 557-bed teaching hospital. PATIENTS: A total of 25 ventilated adult MICU patients were studied-5 in phase 1 and 20 in phase 2. DESIGN: Phase 1 tested the ability of the end-tidal CO2 (ETCO2) monitor to detect flow (and thus accurately detect CO2) through small-bore feeding tubes. A small-bore feeding tube, with stylet in place, was placed 5 cm through the top of the tracheostomy tube ventilator adapter in five consecutive patients. The distal end of the feeding tube was attached to the ETCO2 monitor. The ETCO2 level and waveform were assessed and recorded. Because CO2 waveforms were successfully detected, a convenience sample of 20 adult MICU patients who were having feeding tubes placed (13 Salem sump tubes, 7 small-bore feeding tubes) was then studied. The technique consisted of attaching the ETCO2 monitor to the tubes and observing the ETCO2 waveform throughout placement. RESULTS: The study hypothesis was supported. Of the seven small-bore feeding tubes tested, all were successfully placed on initial insertion. Placement was confirmed by absence of an ETCO2 waveform and by radiograph. Of the 13 Salem sump tubes, 9 were placed successfully on first attempt and confirmed by absence of CO2 and by air bolus and aspiration of stomach contents. ETCO2 waveforms were detected with insertion of four of the Salem sump tubes; the tubes were immediately withdrawn, and placement was reattempted until successful. CONCLUSIONS: The technique described is a simple, cost-effective method of assuring accurate gastric tube placement in critically ill patients.

Adult↗

The value of end-tidal CO2 monitoring when comparing three methods of conscious sedation for children undergoing painful procedures in the emergency department.

BACKGROUND: Many studies have evaluated conscious sedation regimens commonly used in pediatric patients. Recent advances in capnography equipment now enable physicians to assess respiratory parameters, specifically end-tidal CO2 (et-CO2), more accurately in spontaneously breathing sedated children than was possible in the earlier studies. This study was designed to: 1) compare the safety and efficacy of intravenous fentanyl, intravenous fentanyl combined with midazolam, and intramuscular meperidine-promethazine-chlorpromazine (MPC) compound when used for painful emergency department (ED) procedures: and 2) to determine whether the addition of et-CO2 monitoring enabled earlier identification of respiratory depression in this population. METHODS: Forty-two children requiring analgesia and sedation for painful ED procedures were randomly assigned to receive either fentanyl, fentanyl-midazolam, or MPC compound. Vital signs, oxygen saturation, and et-CO2 were monitored continuously. Pain, anxiety, and sedation scores were recorded every five minutes. RESULTS: Respiratory depression (O2 saturation < or = 90% for over the minute or any et-CO2 > or = 50) occurred in 20% of fentanyl, 23% of fentanyl-midazolam, and 11% of MPC patients (P = NS). Of those patients manifesting respiratory depression, 6/8 were detected by increased et-CO2 only. MPC patients required significantly longer periods of time to meet discharge criteria than fentanyl and fentanyl-midazolam patients (P < 0.05). No differences were noted in peak pain, anxiety, or sedation scores. CONCLUSIONS: Fentanyl, fentanyl-midazolam, and MPC produced a high incidence of subclinical respiratory depression. End-tidal CO2 monitoring provided an earlier indication of respiratory depression than pulse oximetry and respiratory rate alone. MPC administration resulted in a significantly delayed discharge from the ED.

Capnography↗

Evaluation of an ambu-bag valve with a self-contained, colorimetric end-tidal CO2 system in the detection of airway mishaps: an animal trial.

OBJECTIVE: Capno-Flo (Kirk Specialty Systems, Carrouton, TX) is a portable pulmonary resuscitator (self inflating ambu-bag--valve system) with a self-contained, colorimetric end-tidal CO2 detector that has the ability to provide continuous CO2 monitoring for up to 2 hours. The purpose of this study is to determine the accuracy and time interval for the Capno-Flo monitor to detect acute airway obstructions and hypopharyngeal extubations in an intubated animal model. SUBJECTS: Five anesthetized, non-paralyzed, mechanically ventilated Yorkshire minipigs. METHODS: Complete and partial airway obstruction was simulated with complete and partial cross-clamping of the endotracheal (ET) tube. Placement of the ET tube into the hypopharynx was performed to simulate accidental extubation. In addition to the Capno-Flo colorimetric indicator, both sidestream (SS) and mainstream (MS) capnography were used to monitor end-tidal CO2 and comparison. The time intervals for the capnograph wave to flatten and for the monitor to display "zero" were recorded after each airway alteration. Each experiment was carried out for 180 seconds, and a total of 25 trials was performed. RESULTS: Complete obstruction produced a color change in the Capno-Flo monitor in 9+/-2 seconds and flattening of the SS and MS waveform in 8+/-2 seconds and 6+/-2 seconds, respectively. The SS and MS monitors displayed zero in 49+/-7 seconds and 19+/-1 seconds, respectively. Partial obstruction did not produce color change, a flattening of the wave, or a monitor display of zero. Hypopharyngeal extubation produced a color change in 10+/-2 seconds, flattening of the SS and MS waveform in 7+/-2 seconds and 7+/-1 seconds, respectively. The SS and MS monitors displayed "zero" in 76+/-16 seconds and 18+/-3 seconds, respectively. CONCLUSION: The Capno-Flo identified all complete airway obstructions and hypopharyngeal extubations rapidly. The CF monitor performed comparable to the SS and MS capnographs. Neither the Capno-Flo, nor the sidestream, nor the mainstream capnographs detected partial airway obstruction. The clinical application of this portable inexpensive capnometer in the continuous monitoring of the intubated patient, especially the transport patient, should be investigated further.

Airway Obstruction↗

Regional carbon dioxide monitoring: a different look at tissue perfusion.

Adequate tissue oxygenation is one of the main therapeutic goals for the critically ill patient. Until recently, the perfusion status of the critically ill and injured has been assessed by global indices such as blood pressure, heart rate, and urine output. However, these global parameters are inadequate in that they fail to demonstrate the actual perfusion status of a patient. Research has shown the splanchnic region to be a pivotal organ bed in response to shock. Because this region shows early signs of hypoperfusion and hypoxia, its monitoring provides for more effective and complete resuscitation. To that end, gastric tonometry offers a noninvasive means by which early symptoms of low flow can be determined, allowing for optimization of tissue perfusion and patient outcome. The most proximal segment of the gastrointestinal tract offers promising information regarding tissue perfusion with the use of sublingual capnography.

Capnography↗

Novel monitoring techniques for use with procedural sedation.

PURPOSE OF REVIEW: A variety of pharmacologic agents used for procedural sedation in children to reduce pain and anxiety may produce respiratory depression and hypotension. Although standard monitoring guidelines include oxygen saturation, this measurement is limited as a guide to respiratory function. This review discusses two new monitoring techniques recently introduced to the pediatric emergency department that facilitate procedural sedation and reduce potential adverse effects of the medications administered. RECENT FINDINGS: Capnography via an end-tidal carbon dioxide monitor measures carbon dioxide concentrations during ventilation. This measurement is independent of oxygen saturation and thereby aids the clinician in identifying hypoventilation and apnea in the sedated patient at an earlier stage than conventional monitoring. The bispectral index monitor objectively measures the depth of sedation by analyzing electroencephalogram signals from a cutaneous probe. This tool enables the physician to titrate sedative medications to a desired effect and thereby reduce the risks associated with oversedation. SUMMARY: Studies have illustrated the use of both devices as adjuncts to current standard monitoring of children in the outpatient setting. These modalities will facilitate the efficacy of procedural sedation in children and improve safety by enabling early recognition of hypoventilation and by reducing the risk of oversedation in children undergoing procedural sedation.

Capnography↗

End-tidal carbon dioxide monitoring in pediatric emergencies.

End-tidal carbon dioxide (CO2) monitoring is useful in the prehospital setting, emergency department, intensive care unit, and operating room. Capnography provides valuable, timely information about the function of both the cardiovascular and respiratory systems. End-tidal CO2 monitoring is the single most useful method in confirming endotracheal tube position. It also provides information about dead space, cardiac output, and airway resistance. A thorough understanding of cardiopulmonary physiology and the technical nuances of capnometry is required for its optimal use in children. This review examines the basic physiology pertinent to end-tidal CO2 monitoring, its clinical applications, and evidence supporting its use in infants and children.

Capnography↗

Expired gas backflow in oxygen delivery tubing.

Using capnography, we investigated the backflow of expired gas into oxygen delivery tubing in 18 sedated patients receiving supplementary oxygen via a disposable facemask during spinal anaesthesia. At 5 cm from the mask, with an oxygen flow of 2 l.min(-1), carbon dioxide was detected in the oxygen delivery tubing of three patients (18%) on coughing. With the patient wearing the facemask but the oxygen tubing disconnected from the oxygen source, carbon dioxide was detectable 1 m from the facemask (i.e. at the fresh gas outlet) in 14 patients. In a second group of 20 similar patients, no carbon dioxide was detected sampling at the fresh gas outlet with flows of 2 and 4 l.min(-1). Assuming that detection of carbon dioxide indicates at least the possibility of contamination, oxygen tubing should be strictly single-use in this setting. Our findings suggest that filters are not required to protect gas supply outlets, provided that the patient's facemask is removed when the fresh gas outlet is disconnected.

Adult↗

Continuous non-invasive end-tidal CO2 monitoring in pediatric inpatients with diabetic ketoacidosis.

INTRODUCTION: Pediatric inpatients with diabetic ketoacidosis (DKA) are routinely subjected to frequent blood draws in order to closely monitor degree of acidosis and response to therapy. The typical level of acidosis monitoring is less than ideal, however, because of the high cost and invasiveness of frequent blood labs. Previous studies have validated end-tidal carbon dioxide (EtCO2) monitoring in the emergency department (ED) for varying periods of time. We extend these findings to the inpatient portion of the hospitalization during which the majority of blood tests are sent. METHODS: All patients admitted to an intermediate care unit in (InCU) a large children's hospital were fitted with an appropriately sized oral/nasal cannula capable of sensing EtCO2. Laboratory studies were obtained according to hospital clinical practice guidelines. In a retrospective analysis, EtCO2 values were correlated with serum total CO2 (stCO2), venous pH (vpH), venous pCO2 (vpCO2), and calculated bicarbonate from venous blood gas (vHCO3-). RESULTS: A total of 78 consecutive episodes of DKA in 72 patients aged 1-21 yr were monitored for 3-38 h with both capnography and laboratory testing, producing 334 comparisons. Initial values were as follows, reported as median (range): stCO2, 11 (4-22) mmol/L; vpH, 7.281 (6.998-7.441); vpCO2, 28.85 (9.3-43.3) mmHg; and vHCO3-, 14 (3-25) mmol/L. EtCO2 was correlated well with stCO2 (r = 0.84, p < 0.001), vHCO3- (r = 0.84, p < 0.001), and vpCO2 (r = 0.79, p < 0.001). CONCLUSIONS: These data support the findings of previous studies limited to ED populations and suggest that non-invasive EtCO2 monitoring is a valuable and reliable tool to continuously follow acidosis in the setting of the acutely ill pediatric patient with DKA. Continuous EtCO2 monitoring offers the practitioner an early warning system for unexpected changes in acidosis that augments the utility of intermittent blood gas determinations.

Adolescent↗

The PEP respiratory monitor: a validation study.

The search for a reliable and accurate respiratory rate monitor for use in non-intubated patients has proved to be a long and fruitless one. A new device fulfilling the criteria for such a monitor has recently been described. The pyroelectric polymer (PEP) device is safe, non-invasive, and cheap. In this study the PEP device, transthoracic impedance, and standard observer counting were all compared with the existing gold standard of capnography in 12 healthy adult volunteers. Using a standard statistical technique it was shown that the PEP device performed as well as a capnograph and was more accurate than the other currently available methods of monitoring respiratory rate.

Adult↗