Detection Of Hypoxemia Research Articles

Assessing the incidence of hyperoxia and the effectiveness of Oxygen Reserve Index-guided FiO2 titration in hyperoxia prevention

BackgroundAlthough pulse oximetry technology, which is considered the standard of care to ensure optimum oxygenation, is indispensable in clinical practice, especially in the detection of hypoxemia, it has some limitations in the detection of hyperoxemia. Oxygen Reserve Index can provide clinicians with a crucial pathway in detecting and preventing hyperoxia, noninvasively. Our aim in this study is to determine the hyperoxia detection ability of ORi and to investigate the effectiveness of ORi and SpO2-guided FiO2 titration in preventing hyperoxia.MethodsThis prospective randomized study was conducted in the operating theater of Health Sciences University İzmir Tepecik Training and Research Hospital from September 1, 2020, to December 1, 2022. Patients undergoing major abdominal surgery were divided into two groups: the control group and the SpO2 + ORi group. FiO2 titration was performed in the SpO2 + ORi group to maintain the ORi between 0.00 and 95% < SpO2 ≤ 98%. Parameters were recorded before induction, 10 min after intubation, and every hour during the operation.ResultsA positive linear relationship of 75.8% (r = 0.758) was found between PaO2 and ORi in the ORi + SpO2 group (p < 0.001). Moderate hyperoxemia was observed in 31.6% of patients in the control group, while it was not observed in the ORi + SpO2 group at the 3rd hour. PaO2 values decreased significantly over time in the ORi + SpO2 group with FiO2 titration (p < 0.001).ConclusionThe combined use of SpO2 and ORi has been demonstrated to successfully guide FiO2 titration for optimal oxygenation and reduce hyperoxemia.

Accuracy of Multiple Pulse Oximeters in Stable Critically Ill Patients.

An accurate SpO2 value is critical in order to optimally titrate oxygen delivery to patients and to follow oxygenation guidelines. Limited prospective data exist on real-world performance of pulse oximeters in critically ill patients. The objective of this study was to assess accuracy and bias of the SpO2 values measured by several oximeters in hospitalized subjects. We included stable adults in the ICU with an arterial catheter in place. Main exclusion criteria were poor SpO2 signal and SpO2 > 96%. In each subject, we simultaneously evaluated 4 oximeters: Nonin (Plymouth, Minnesota) embedded in the FreeO2 device (OxyNov, Québec City, Québec, Canada), Masimo (Radical-7, Masimo, Irvine, California), Philips (FAST, Philips, Amsterdam, the Netherlands), and Nellcor (N-600, Medtronic, Minneapolis, Minnesota). Arterial blood gases were drawn and simultaneously each oximeters' SpO2 values were collected. SpO2 values were compared to the reference (arterial oxygen saturation [SaO2 ] value) to determine bias and accuracy. The ability for oximeters to detect hypoxemia and the impact of oximeters on oxygen titration were evaluated. We included 193 subjects (153 male, mean age 66 y) in whom 211 sets of measurements were performed. The skin pigmentation evaluated by Fitzpatrick scale showed 96.2% of subjects were light skin (types 1 and 2). One oximeter overestimated SaO2 (Philips, +0.9%), whereas the 3 others underestimated SaO2 (Nonin -3.1%, Nellcor -0.3%, Masimo -0.2%). SaO2 was underestimated with Nonin oximeter in 91.3% of the cases, whereas it was overestimated in 55.2% of the cases with Philips oximeter. Moderate hypoxemia (SaO2 86-90% or PaO2 55-60 mm Hg) was detected in 92, 33, 42, and 11% of the cases with Nonin, Nellcor, Masimo, and Philips, respectively. We found significant bias and moderate accuracy between the tested oximeters and the arterial blood gases in the studied population. These discrepancies may have important clinical impact on the detection of hypoxemia and management of oxygen therapy.

Screening of Newborn by Pulse Oximetry at Birth for the Critical Congenital Heart Disease

Background: Early diagnosis of congenital heart disease is important for a good clinical outcome. Unrecognized or delayed diagnosis of some severe congenital heart diseases can lead to cardiac failure, cardiovascular collapse, and even death. Pulse oximetry screening (POS) in newborns has been shown to enhance the detection of critical congenital heart disease (CCHD). Clinical evaluation is likely to miss the diagnosis in first few hours of hospital stay after birth due to absence of signs and symptoms of CCHD. In the absence of clinical findings during early neonatal period, the best parameter that can be assessed, is the detection of hypoxemia by pulse oximetry screening. Aims and Objectives: Usefulness of pulse oximetry in newborn for early detection of Critical Congenital Heart Disease (CCHD). Material and Methods: This Prospective Observational Study was conducted on 125 newborn babies in postnatal ward at tertiary care centre for a period of 2 years satisfying the inclusion and exclusion criteria. Evaluation was done between 24 to 48 hours of birth with pulse oximeter. Institutional ethics committee permission was taken prior to study. Results and Conclusion: Total 125 neonates were screened by pulse oximeter, 2 were detected to have positive screen for Congenital Heart Disease (CHD) of which 1 had CCHD confirmed by echocardiography. Study revealed that Pulse Oximetry screening can be an important screening tool in routine neonatal care for early detection of CCHD.

Original Research Article on Study of Correlation between Various Clinical Parameters and Hypoxemia in Children with Lower Respiratory Tract Infection of Age 2 Months to 5 Years

A case control study was conducted from October 2018 to September 2020 by taking children between the age group 2 months to 5 years, admitted to Sishu Bhawan and SCB Medical College Hospital, Cuttack with an acute history of cough and rapid respiration or difficulty in breathing, to know the correlation between various clinical parameters and hypoxemia along with ability of each parameter to predict the presence of hypoxemia in children. Among 109 children, 50 children were hypoxemic and 59 children were non hypoxemic with the prevalence of hypoxemia about 45.8%. Among symptoms in children with Acute Lower Respiratory Tract Infection (ALRI), inability to feed, cough and difficulty in breathing had a sensitivity of 100%, 98% and 92% respectively and specificity was maximum for difficulty in breathing (62.7%) to predict hypoxemia. On comparison between hypoxemic and non-hypoxemic children difficulty in breathing and inability to feed had a p value &lt;0.001 and was statistically significant. Among signs in children with ALRI, appearance of the child, lower chest retraction, respiratory rate had a sensitivity of 100%, 100% and 98% respectively to predict hypoxemia. Central cyanosis was the most specific sign with the specificity of 100% to predict hypoxemia followed by grunting with a specificity of 96.6%. When compared between hypoxemic and non-hypoxemic children the p-value was very highly significant for appearance of nasal flaring, grunting, suprasternal indrawing parameters whereas upon combination of variables, a combination of cough, inability to feed, tachypnoea and the combination of cough, subcostal retractions, tachypnoea had high sensitivity of 96% and 95% respectively to predict hypoxemia in children with ALRI. Combination of difficulty in breathing, cyanosis and grunting had high specificity of 98%. Keeping in view of less feasibility of detection of hypoxemia in lower respiratory tract infection by pulse oximeter and ABG in developing countries and no available study in the state of Odisha, this study is conducted in an attempt to find out the alternative methods by various clinical parameters to detect hypoxemia which are easily recognized by the health personnel in developing countries for the further management of Lower Respiratory Tract Infection (LRTI). Keywords: Hypoxemia, Acute Lower Respiratory Tract Infection, Lower Respiratory Tract Infection, Management.

Assessment of Oxygen Saturation Using Pulse Oximetry in Patients with Steady State HbSS

Background: The exact consequence of hypoxemia SCA is unclear, however, many studies have shown haemoglobin desaturation is common in patient with SCA even at steady state, and may predispose to several complications including pulmonary hypertension, stroke and acute chest syndrome. Therefore, detection of hypoxemia is important in patients with SCA. Objectives: We sought to compare SpO2 of patients with HbSS in steady state and healthy individuals with HbAA genotype; and to determine the prevalence of hypoxemia amongst HbSS patients during steady state. Materials and Methods: This is a prospective cross-sectional study involving ninety three adults with SCA in steady state and forty-eight healthy age and sex matched HbAA participants as controls. The oxygen saturation was recorded using a finger pulse oximeter (Suaoki, Model FS20A). Results: The HbSS patients had a significantly lower mean SpO2 of 95.5% ( 4.1) compared to 99.06% ( 1.14) for the healthy HbAA group (p=0.0001). Male and female HbSS patients had a comparable SpO2 (95.8% vs 96.1%, p=0.610). Similarly, mean SpO2 was similar in male and female HbAA group (p=0.258). The prevalence of hypoxemia among the HbSS patients was 30.25% compared to 2.7% amongst the HbAA. The lowest SpO2 recorded among the HbSS patients was 88%. Conclusion: The prevalence of hypoxemia in steady state HbSS patients was high. This finding underscores the importance of monitoring HbSS patients for prompt detection of hypoxemia, and to institute therapy where necessary to prevent complications including pulmonary hypertension and cerebrovascular disease.

Physiologic Considerations in Detection of Hypoxemia during Vasoconstriction: Radial Artery Compared to Various Pulse Oximeter Sensor Sites

Physiologic Considerations in Detection of Hypoxemia during Vasoconstriction: Radial Artery Compared to Various Pulse Oximeter Sensor Sites

Pulmonary gas exchange and acid-base status during immobilisation of black rhinoceroses (Diceros bicornis) in Zimbabwe.

When immobilising wildlife, adverse side effects can include hypoxaemia, acidosis and hypertension. Pulmonary gas exchange and acid–base status were evaluated during immobilisation of 25 free-ranging and one boma-held black rhinoceros (Diceros bicornis) in Zimbabwe. The effect of different body positions on arterial oxygenation was evaluated. A combination of the following drugs was used: an opioid (etorphine or thiafentanil), azaperone and an α2-adrenoceptor agonist (detomidine or xylazine). Respiratory and heart rates, rectal temperature and pulse oximetry–derived haemoglobin oxygen saturation were recorded. Serial arterial blood samples were analysed immediately in the field. Marked hypoxaemia and hypercapnia were recorded in immobilised free-ranging black rhinoceroses. Arterial oxygenation was higher during sternal compared to lateral recumbency. Most rhinoceroses developed acidaemia of respiratory and metabolic origin. Initially high lactate concentrations in free-ranging rhinoceroses decreased during immobilisation. Pulse oximetry was unreliable in the detection of hypoxaemia. Positioning in sternal recumbency and routine use of oxygen supplementation are recommended in the management of immobilised rhinoceroses as measures to improve arterial oxygenation.

Detection of hypoxemia and hyperoxemia by pulse oximetry in neonates and children

Objective To assess the validity of pulse oximetry for detectinghypoxemia and hyperoxemia in neonates and children.Methods This was a diagnostic test study conducted in NeonatalIntensive Care Unit (NICU). The subjects of the study wereneonates of 0-28 days and children aged one month to 14 yearsin Pediatric Intensive Care Unit (PICU) of Sardjito Hospital.Hypoxemia and hyperoxemia were obtained by using NellcorRpulse oximetry, at the same time as blood gas analysis was obtainedas a gold standard.Results There were 240 neonates and 268 children enrolled inthis study. Pulse oximetry test with cut-off point 91% (neonates)and 90% (children) for detecting hypoxemia had sensitivity of81% and 80%, specificity of 79% and 95% positive predictivevalue of 54% and 82% negative predictive value of93% and 93%positive likelihood ratio of 3. 79 and 14.20 and negative likelihoodratio of0.25 and 0.24. Pulse oximetry test with cut-off point 95%(neonates) and 97% (children) for detecting hyperoxemia hadsensitivity of 7 8% and 81% specificity of 66% and 79%, positivepredictive value of77% and 76% negative predictive value of 66%and 83% positive likelihood ratio of 2.26 and 3.84 and negativelikelihood ratio of 0.34 and 0.24.Conclusion Pulse oximetry has a fairly good validity in detectinghypoxemia in neonates and children and in detecting hyperoxemiain children to however, it is not good enough to be used to detecthyperoxemia in neonates.

Photoplethysmography respiratory rate monitoring in patients receiving procedural sedation and analgesia for upper gastrointestinal endoscopy

The value of capnography during procedural sedation and analgesia (PSA) for the detection of hypoxaemia during upper gastrointestinal (UGI) endoscopic procedures is limited. Photoplethysmography respiratory rate (RRp) monitoring may provide a useful alternative, but the level of agreement with capnography during PSA is unknown. We therefore investigated the level of agreement between the RRp and capnography-based RR (RRc) during PSA for UGI endoscopy. This study included patients undergoing PSA for UGI endoscopy procedures. Pulse oximetry (SpO2) and RRc were recorded in combination with Nellcor 2.0 (RRp) monitoring (Covidien, USA). Bland–Altman analysis was used to evaluate the level of agreement between RRc and RRp. Episodes of apnoea, defined as no detection of exhaled CO2 for minimal 36 s, and hypoxaemia, defined as an SpO2 < 92 %, were registered. A total of 1054 min of data from 26 patients were analysed. Bland–Altman analysis between the RRc and RRp revealed a bias of 2.25 ± 5.41 breath rate per minute (brpm), with limits of agreement from −8.35 to 12.84 brpm for an RR ≥ 4 brpm. A total of 67 apnoea events were detected. In 21 % of all apnoea events, the patient became hypoxaemic. Hypoxaemia occurred 42 times with a median length of 34 (19–141) s, and was preceded in 34 % of the cases by apnoea and in 64 % by an RRc ≥ 8 brpm. In 81 % of all apnoea events, photoplethysmography registered an RRp ≥ 4 brpm. We found a low level of agreement between capnography and the plethysmography respiratory rate during procedural sedation for UGI endoscopy. Moreover, respiratory rate derived from both the capnogram and photoplethysmogram showed a limited ability to provide warning signs for a hypoxaemic event during the sedation procedure.

Early detection of critical congenital heart disease in newborns using pulse oximetry screening

Background: Congenital heart diseases which are dependent on the ductusarteriosus to maintain adequate oxygenation or systemic blood flow are termed as a critical congenital heart disease (CCHD). Delay in the diagnosis of CCHD is the major cause leading to morbidity and mortality in newborn infants. Clinical evaluation is likely to miss the diagnosis in first few hours of hospital stay after birth due to absence of signs and symptoms of CCHD.In the absence of clinical findings during early neonatal period, the best parameter that can be assessed is the detection of hypoxemia by pulse oximetry screening. Objectives: To record the value of Pulse Oximetry within 24 hours of birth and evaluate Pulse Oximetry as screening tool for early diagnosis of CCHD. Methods: Longitudinal descriptive study was conducted on total 700 intramural neonates, satisfying the inclusion and exclusion criteria, who were evaluated within 24 hours of birth with currently available pulse oximeter, after the Institutional Ethical Committee approval. The study was conducted over a period of 4 months. Part-A: Neonatal Case Record, Part-B: Pulse Oximetry Screening Record, Part-C: Clinical Examination Record, Part-D: Echocardiography Record. Results and Conclusion: Total 700 neonates were screened by pulse oximeter with consecutive sampling method. 4 (0.57%) subjects were detected to have positive screen and the diagnosis was confirmed by echocardiography. Study revealed that Pulse Oximetry Screening can be an important primary screening tool in routine neonatal care for early detection of Critical Congenital Heart Diseases particularly in rural setup.

Pulse Oximeter Oxygen Saturation in Prediction of Arterial Oxygen Saturation in Liver Transplant Candidates

Background:Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.Objectives:The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.Patients and Methods:Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.Results:Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.Conclusions:Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

Evaluation of accuracy of portable fingertip pulse oximeter, as compared to that of a hospital oximeter with digital sensor

The pulse oximeter is a device that noninvasively provides continuous information about the peripheral oxygen saturation (SpO2) rate. This device is utilized in the detection of hypoxemia, due to its able to sense changes in hemoglobin oxygen saturation. The objective of this study was to verify the accuracy of the Choice® Medical MD300C3 Fingertip Pulse Oximeter, as compared to that of a hospital oximeter coupled with a Drager® Infinity Delta monitor, with the purpose of using this first methodology in dental procedures to monitor the peripheral oxygen saturation (SpO2) of patients submitted to dental treatments. Fifty-five adult patients, both genders, were selected in the Santa Casa Hospital of Maringa, Brazil. The volunteers did not present cardiac problems, prosthetic cardiac valves, pacemakers, or pulmonary diseases, and were not pregnant or children. Each patient received a portable fingertip pulse oximeter (PPO) on the middle finger of the left hand and the hospital oximeter (control device) on the forefinger of the same hand. A total of six measurements were developed. The Pearson correlation coefficient and the Bland and Altman method was used to calculate the statistical analysis. No statistically significant difference was found between the measurements taken by the utilized devices. The average of comparative analysis presented by the devices was 0.2337 ± 0.4355 (mean ± SD), suggesting a strong correlation between the obtained results. According to the methodology of the research, the PPO has similar accuracy to the conventional hospital oximeter with digital sensor. The PPO can be used in dental treatments.

Esophageal pulse oximetry is more accurate and detects hypoxemia earlier than conventional pulse oximetry during general anesthesia

The esophagus is perfused directly by prominent arteries and may provide a more consistent tissue source for pulse oximetry. The goal of this study was to evaluate the sensitivity and accuracy of an esophageal pulse oximetry probe on patients during controlled hypoxemia in comparison to measurements obtained with conventional pulse oximetry (SpulseO(2)). Forty-five ASA I-II adult patients were included in this prospective observational study. Nellcor digital oximetric probes were placed on finger tips for SpulseO(2) before anesthesia. After tracheal intubation, an esophageal probe was placed in the lower segment of the esophagus for esophageal oximetric monitoring (SoesO(2)). All patients were disconnected from the breathing circuit to establish a controlled hypoxemia, and were re-connected to the breathing circuit and ventilated with 100% oxygen immediately when SoesO(2) dropped to 90%. Matched SoesO(2) and SpulseO(2) readings were recorded when SoesO(2) measurements were at 100%, 95%, 90% and the lowest reading. The time for SoesO(2) and SpulseO(2) to drop from 100% to 95%, 90% and return to 100% was recorded. Oxygen saturation from arterial blood samples (SartO(2)) was also measured at each time point respectively. The linear correlation coefficient of the regression analysis between SartO(2) and SoesO(2) was 0.954. The mean ± 2SD of the difference was 0.3% ± 4.3% for SoesO(2) vs. SartO(2) and 6.8% ± 5.6% for SpulseO(2) vs. SartO(2) (P < 0.001). The 95% confidence interval for the absolute difference between SoesO(2) and SartO(2) was 0.3% to 0.7% and 6.2% to 7.4% between SpulseO(2) and SartO(2). The time to reach 90% saturation measured with SoesO(2) was approximately 94 seconds earlier than the SpulseO(2) (P < 0.001). In conclusion, SoesO(2) is more accurate and enables earlier detection of hypoxemia when compared to conventional pulse oximetry during hypoxemia for patients undergoing general anesthesia.

Clinical predictors of hypoxemia in children with acute lower respiratory tract infections

Background and objectives: Acute lower respiratory tract infections (ALRI) are the leading cause of morbidity and mortality among children in developing countries. Pulse oxymetry is a simple technique to determine the oxygen saturation. However, the detection of hypoxemia by use of pulse oxymetry is not available in most situations in developing countries; in addition, the availability of supplementary oxygen is inadequate. It is therefore, important to identify hypoxemia accurately in children by using of clinical signs. The objective of this study was to find out the clinical signs and symptoms that predict hypoxemia in acute lower respiratory tract infection. Methods: A well matched case control study was performed on 120 children from 2 months to 5 years of age admitted with acute lower respiratory tract infections (ALRI) to the emergency department of Raparin Pediatric Teaching Hospital -Erbil, from 1st January 2009 to 1st April 2010.Clinical symptoms and signs were recorded .Hypoxemia was defined as oxygen saturation less than 95%. A portable oxymeter was used to measure oxygen saturation with an appropriately sized sensor on the finger or the toe. The reading was taken while the child was breathing room air. The clinical symptoms and signs to predict the presence of hypoxemia were evaluated. Results: Sixty (50%) children were hypoxemic. The median O2 saturation was 91.2%with a range of 72-93.8%. Physical signs including intercostal and subtotal retractions, supraclavicular recessions, grunting, nasal flaring, cyanosis, head nodding, were statistically associated with hypoxemia. Conclusion: None of the clinical features either alone or in combinations has sufficient sensitively and specificity to predict hypoxemia in children with acute lower respiratory tract infections, therefore pulse oxymetry is desirable for identification of hypoxemia.

Accuracy of Pulse Oximetry in the Detection of Hypoxia in Liver Transplant Candidates

Hypoxia is common in patients with chronic liver disease. Screening guidelines for detecting the presence of arterial hypoxemia do not exist. The aim of this study was to investigate the accuracy and utility of pulse oxymetry in the detection of hypoxemia (PaO2<65) in a group of patients with liver cirrhosis who were candidate for liver transplantation. Two hundred and ninety-five transplant candidates enrolled in this study. Arterial oxyhemoglobin saturation was obtained by pulse oxymetry (SpO2) and compared with simultaneous arterial blood gas (ABG) oxyhemoglobin values (SaO2). Bias, the overestimation or underestimation of one method compared with another, is defined as the difference between SpO2 and SaO2. SpO2 overestimated SaO2 in 78.3% (n=231) and underestimated in 18.6% (n=54) cases. The bias was over 4% or less than -4% (Bias4) in 11.6% (n=34) of the cases and significantly different between the patients with SaO2 =94%. PaO2 =65 mmHg (p=0.000) and SpO2 =94% (p=0.003). Also, when we used the cut-off level of A-a O2 gradient =20 and =15, the bias was significantly different between the patients (p=0.000). Pulse oximetry is a useful screening test to detect hypoxemia in patients with liver disease.

Oxygen concentrators: a practical guide for clinicians and technicians in developing countries

Hypoxaemia is a common problem causing child deaths in developing countries, but the cost-effective ways to address hypoxaemia are ignored by current global strategies. Improving oxygen supplies and the detection of hypoxaemia has been shown to reduce death rates from childhood pneumonia by up to 35%, and to be cheaper per life saved than other effective initiatives such as conjugate pneumococcal vaccines. Oxygen concentrators provide the cheapest and most consistent source of oxygen in health facilities where power supplies are reliable. To implement and sustain oxygen concentrators requires strengthening of health systems, with clinicians, teachers, administrators and technicians working together. Programmes built around the use of pulse oximetry and oxygen concentrators are an entry point for improving quality of care, and are a unique example of successful integration of appropriate technology into clinical care. This paper is a practical and up-to-date guide for all involved in purchasing, using and maintaining oxygen concentrators in developing countries.

Validity of pulse oximetry in detection of hypoxaemia in children: comparison of ear, thumb and toe probe placements

This study of paediatric intensive care patients aimed to determine where pulse oximetry probes shouid be placed to obtain the most accurate and reliable readings of peripheral oxygen saturation (SpO2). Using arterial blood gas analysis (SaO2) as the gold standard and SpO2 92% and SaO2 < 90% as indicators of hypoxaemia, negative predictive values of SpO2 were 96%, 98% and 98% at the ear, thumb and big toe respectively in 110 children, and 93% at all 3 sites in 90 neonates. The highest clinical agreement between SaG, and SpO2 was for ear probes in children (kappa = 0.70) and the lowest was for big toe probes (kappa = 0.57 and 0.28 in children and neonates respectively).

Implementing an oxygen programme in hospitals in Papua New Guinea

In Papua New Guinea (PNG), the most common cause of death among children under 5 years of age is pneumonia. Children with severe pneumonia need antibiotics and oxygen but oxygen shortages are common owing to the cost and complex logistics of transporting it in cylinders. Detection of hypoxaemia using clinical signs can be difficult, especially in highly pigmented children in whom cyanosis is difficult to recognise. Pulse oximetry is the most reliable, non-invasive way of detecting hypoxaemia. However, most hospitals in PNG do not have pulse oximetry. We proposed that the installation of a reliable, sufficient and cheap supply of oxygen in hospitals coupled with the use of pulse oximetry would make a significant difference to child survival rates in PNG. Oxygen concentrators, which extract oxygen from ambient air, were installed in the children's wards of five hospitals during 2005. Pulse oximeters were also introduced to enable better detection of hypoxaemia. This paper describes the technical aspects of this programme: the equipment used and the rationale behind choosing it, the installation, commissioning and testing processes. The ongoing training of clinical and engineering staff as well as two follow-up evaluations are described.

Utility of pulse oximetry in the detection of arterial hypoxemia in liver transplant candidates.

Hepatopulmonary syndrome, arterial hypoxemia caused by intrapulmonary vasodilatation, occurs in approximately 10% of patients with cirrhosis. The severity of hypoxemia affects liver transplant candidacy and is associated with increased morbidity and mortality posttransplantation. Screening guidelines for detecting the presence of arterial hypoxemia do not exist. The aim of this study is to investigate the accuracy and utility of pulse oximetry in the detection of hypoxemia (PaO(2) < 70 mm Hg) in patients with cirrhosis. Two hundred prospective liver transplant candidates were compared with 94 controls. Arterial oxyhemoglobin saturation was obtained by pulse oximetry (SpO(2)) and compared with simultaneous arterial blood gas (ABG) oxyhemoglobin values (SaO(2); bias = the difference). PaO(2), carboxyhemoglobin, methemoglobin, and routine clinical and biochemical parameters were investigated to account for the bias. SpO(2) overestimated SaO(2) in 98% of patients with cirrhosis (mean bias, 3.37%; range, -1% to 10%). Forty-four percent of patients with cirrhosis and controls had a bias of 4% or greater. No clinical or biochemical parameters of cirrhosis accounted for the overestimation of pulse oximetry. Twenty-five subjects with cirrhosis were hypoxemic, and an SpO(2) of 97% or less showed a sensitivity of 96% and a positive likelihood ratio of 3.9 for detecting hypoxemia. An SpO(2) of 94% or less detected all subjects with an arterial PaO(2) less than 60 mm Hg. Pulse oximetry significantly overestimates arterial oxygenation, and the inaccuracy is not influenced by liver disease. Nevertheless, pulse oximetry can be a useful screening tool to detect arterial hypoxemia in patients with cirrhosis, but a higher threshold for obtaining an ABG must be used.

Delays in the Detection of Hypoxemia Due to Site of Pulse Oximetry Probe Placement

Delays in the Detection of Hypoxemia Due to Site of Pulse Oximetry Probe Placement