The impact of a postoperative oxygen therapy protocol on use of pulse oximetry and oxygen therapy

BACKGROUND: Recent evidence suggests that both pulse oximetry monitoring and oxygen (O2) therapy may be used inappropriately at times, implying the need for improved use of pulse oximetry by health-care providers. METHODS: We studied the clinical and financial impact of a postoperative O2-therapy protocol in 2 groups of patients. Group 1 (n = 20) was comprised of patients whose physicians made all O2 therapy management decisions. Group 2 (n = 20) was comprised of patients whose O2 therapy management was performed by respiratory therapists according to an algorithm with a stop criterion of SpO2 > or = 92%. The duration of postoperative O2 therapy, the frequency of unnecessary O2 therapy, and group totals of SpO2 measurements were compared between groups using the Mann-Whitney Rank Sum Test. RESULTS: O2 therapy was used on average (SD) 3.45 (1.28) days/patient in Group 1 and 2.1 (0.64) days/patient in Group 2 (p < 0.003). Sixteen Group-1 patients continued to receive O2 at least 24 hours after achieving a room-air SpO2 > or = 92%. Group 1 had 57 SpO2 measurements and Group 2 had 24 (p < 0.003). No adverse clinical events ascribed to hypoxemia were noted in either group. CONCLUSIONS: Our experience suggest that implementing a uniform, clinically appropriate 'stop criterion' for low-flow O2 therapy in nonthoracic postoperative patients can shorten the duration of O2 therapy and reduce the number of SpO2 measurements without incurring additional complications.     

Noninvasive monitoring of oxygenation during one-lung ventilation: A comparison of transcutaneous oxygen tension measurement and pulse oximetry

Oxygenation was monitored concomitantly by measurement of transcutaneous oxygen tension and by pulse oximetry, and the data were compared with arterial blood oxygen tension and saturation values in 10 patients who became hypoxemic when undergoing thoracotomy and one-lung ventilation. A steep decrease in arterial blood oxygen tension was obvious immediately after the institution of one-lung ventilation, reaching the lowest mean value of 63 ± 2 mm Hg (± SEM) at 12 minutes. Despite significant correlation between transcutaneous oxygen tension and arterial blood oxygen tension during one-lung ventilation (r = 0.75;P < 0.001), the delay in the transcutaneous oxygen tension response resulted in underestimation of the severity of hypoxemia at the beginning of one-lung ventilation. In contrast, the decrease in arterial blood oxygen saturation from 97.9 ± 0.3% to 92.2 ± 0.8% as measured by CO-Oximeter was accurately followed by pulse oximetry with almost beat-to-beat response, bringing about a highly significant linear correlation between the two methods (r = 0.93;P < 0.001). We conclude that pulse oximetry is a simpler and more rapidly responding method than measurement of transcutaneous oxygen tension for detection of hypoxemia during one-lung ventilation in adults.     

End-tidal oxygen concentration and pulse oximetry for monitoring oxygenation during intratracheal jet ventilation

Objective. In this study, we evaluated the usefulness of end-tidal oxygen monitoring during intratracheal jet ventilation (ITJV) for endolaryngeal laser surgery.Methods. A total of 20 consecutive patients of both genders scheduled for endolaryngeal procedures under general anesthesia were studied. Inspiratory oxygen concentration and respiratory rate were varied, with patients serving as their own controls. Readings of pulse oximetry, airway oxygen, and carbon dioxide concentrations were recorded, and arterial blood samples for blood gas analysis were taken.Results. At jet cycle rates of 20 cycles/min, end-tidal oxygen (ETo₂) concentration indicated alveolar hypoxia 30 to 60 sec before hypoxemia was detected by pulse oximetry. Jet mixing of inspiratory and expiratory gas caused a larger difference between end-tidal and arterial gas concentrations than normally seen with conventional ventilation. Correlations between ETo₂ concentrations, oxygen saturations, and arterial oxygen levels depended on respiratory rate and inspiratory oxygen concentration; correlations were stronger at low than at high inspiratory oxygen concentrations and stronger at low than at high respiratory rates.Conclusions. ETo₂ concentration should be maintained well over 21% during ITJV to prevent alveolar and arterial hypoxia. Monitoring of respiratory oxygen concentrations at jet cycle rates of 20 cycles/min and less verifies safe oxygen levels during laser surgery, and confirms adequate alveolar oxygenation.We are grateful to Anneli Innanmaa, RN, for her skillful help with this study, and to Hannu Laine, fine mechanic, for the construction of the copper tubes.Grants were received from Instrumentarium Scientific Foundation, Helsinki, for construction of the special jet ventilator and the pressure curve monitor. Datex, Helsinki, provided the OSCAR OXY monitor.Part of the results of this study were presented at the 10th World Congress of Anaesthesiologists, The Hague, 1992 (Abstract A41 [ISBN 90-800899-2-3]).     

Assessing assertive behaviour in student nurses: a comparison of assertion measures

This study compared four different assertive measurements used to assess student-nurse behaviour. The measurements employed included a semantic differential 'subjective self-report', the Rathus Assertiveness Schedule, a behavioural test, and observer ratings. The study was divided into three different phases. In phase one, subjects (n = 19) were requested to complete the two self-report measures. Several days later, they were asked to partake in a behavioural test which took the form of a response to an unreasonable request. The final phase entailed observers (n = 9) viewing a video-recording of the behavioural test (without sound) and rating subjects on levels of assertiveness. Analyses of the results revealed only one significant finding, namely that there was a positive relationship between the scores on the Semantic Differential Measurement and the Rathus Assertiveness Schedule (P less than 0.05). No other significant results emerged. The findings of this investigation are discussed in the context of the role of assertive behaviour in nursing.     

A novel device for measuring long-term oxygen therapy adherence: a preliminary validation

INTRODUCTION: Current methods for measuring patient adherence to long-term oxygen therapy fail to measure the actual amount of time the patient is inhaling oxygen and the pattern of oxygen use within the day. We have developed a novel oxygen-adherence monitor to address these limitations, and this report introduces the monitor and provides preliminary data validating its use. METHODS: This battery-powered monitor attaches to the oxygen source and detects respiratory-related pressure fluctuations transmitted through the nasal cannula. The monitor takes a measurement over a 25-second period, at 4-min intervals. It detects and stores data on 4 different states that describe the patient's actual use of the oxygen source and nasal cannula: source-off/cannula-off, source-off/cannula-on, source-on/cannula-off, and source-on/cannula-on. We studied the monitor's performance with 10 patients with chronic obstructive pulmonary disease, during a directly-observed sequence of using and not using supplemental oxygen via nasal cannula, while sitting and walking. RESULTS: The monitor correctly detected 122 out of 129 measurements among all participants, yielding a 95\% detection accuracy. CONCLUSION: A monitor that objectively measures oxygen inhalation, rather than oxygen expenditure, may help improve the management of patients on long-term oxygen therapy.     

Non-invasive estimation of jugular venous oxygen saturation: a comparison between near infrared spectroscopy and transcutaneous venous oximetry

The ability of practitioners to assess the adequacy of global oxygen delivery is dependent on an accurate measurement of central venous saturation. Traditional techniques require the placement of invasive central venous access devices. This study aimed to compare two non-invasive technologies for the estimation of regional venous saturation (reflectance plethysmography and near infrared spectroscopy [NIRS]), using venous blood gas analysis as gold standard. Forty patients undergoing cardiac surgery were recruited in two groups. In the first group a reflectance pulse oximeter probe was placed on the skin overlying the internal jugular vein. In the second group, a Somanetics INVOS oximeter patch was placed on the skin overlying the internal jugular vein and overlying the ipsilateral cerebral hemisphere. Central venous catheters were placed in all patients. Oxygen saturation estimates from both groups were compared with measured saturation from venous blood. Twenty patients participated in each group. Data were analyzed by the limits of agreement technique suggested by Bland and Altman and by linear regression analysis. In the reflectance plethysmography group, the mean bias was 4.27% and the limits of agreement were 58.3 to −49.8% (r² = 0.00, p = 0.98). In the NIRS group the mean biases were 10.8% and 2.0% for the sensors attached over the cerebral hemisphere and over the internal jugular vein, respectively, and the limits of agreement were 33.1 to −11.4 and 19.5 to −15.5% (r² = 0.22, 0.28; p = 0.04, 0.03) for the cerebral hemisphere and internal jugular sites, respectively. While transcutaneous regional oximetry and NIRS have both been used to estimate venous and tissue oxygen saturation non-invasively, the correlation between estimates of ScvO₂ and SxvO₂ were statistically significant for near infrared spectroscopy, but not for transcutaneous regional oximetry. Placement of cerebral oximetry patches directly over the internal jugular vein (as opposed to on the forehead) appeared to approximate internal jugular venous saturation better (lower mean bias and tighter limits of agreement), which suggests this modality may with refinement offer the practitioner additional clinically useful information regarding global cerebral oxygen supply and demand matching.     

Drug-induced headache: long-term results of stationary versus ambulatory withdrawal therapy

Drug-induced headache is a well-known complication of the treatment of primary headache disorders, and its successful management is only possible by withdrawal therapy. However, it is unknown whether ambulatory or stationary withdrawal is the therapy preferred. We conducted a prospective study on the outcome of stationary versus ambulatory withdrawal therapy in patients with drug-induced headache according to the International Headache Society criteria. Out of 257 patients with the diagnosis of drug-induced headache during the study period, 101 patients (41 after ambulatory and 60 after stationary withdrawal therapy) could be followed up for 5.9 +/- 4.0 years. The total relapse rate after successful withdrawal therapy was 20.8% (14.6% after ambulatory and 25.0% after stationary withdrawal therapy, p < 0.2). The main risk factors for a relapse were male sex (OR = 3.9, CI = 1.3-11.6), intake of combined analgesic drugs (OR = 3.8, CI = 1.4-10.3), administration of naturopathy (OR = 6.0, CI = 1.2-29.3), and a trend to tension-type headache as the primary headache disorder (OR = 1.9, CI = 0.6-53.0). Our data suggest that neither the method of withdrawal therapy nor the kind of analgesic and other antimigraine drugs has a major impact on the long-term result after successful withdrawal therapy. Patients with risk factors according to our findings should be informed and monitored regularly, and combined drugs should be avoided. Furthermore, our data suggest that there is a need for research on individual psychological and behavioral risk factors for relapse after successful withdrawal therapy in drug-induced headache.     

Pulse oximetry: theory and applications for noninvasive monitoring.

Noninvasive measurement of arterial oxygen saturation (SaO2) by pulse oximetry is widely acknowledged to be one of the most important technological advances in monitoring clinical patients. Pulse oximeters compute SaO2 by measuring differences in the visible and near infrared absorbances of fully oxygenated and deoxygenated arterial blood. Unlike clinical blood gas analyzers, which require a sample of blood from the patient and can provide only intermittent measurement of patient oxygenation, pulse oximeters provide continuous, safe, and instantaneous measurement of blood oxygenation. Here I review the theoretical background behind this advanced technology, instrumentation requirements, practical instrument calibration, common features of commercial pulse oximeters, specific clinical applications, and performance limitations of pulse oximeters.     

Assessing traumatic brain injury outcome measures for long-term follow-up of community-based individuals

OBJECTIVES: To determine which outcome measures are best and least suited for assessing long-term functional outcome of individuals with traumatic brain injury (TBI) in the community. DESIGN: Survey of participants in the community an average of 5 years after TBI. A battery of outcome measures was given. SETTING: Community in northern California after inpatient rehabilitation. PARTICIPANTS: Forty-eight adult individuals with prior moderate to severe TBI. All subjects had received inpatient rehabilitation 2 to 9 years previously and could be reached for telephone interview. MAIN OUTCOME MEASURES: The Community Integration Questionnaire, Neurobehavioral Functioning Inventory (NFI), Patient Competency Rating Scale (PCRS), Level of Cognitive Functioning Scale (LCFS), FIM instrument, Functional Assessment Measure (FIM+FAM), Supervision Rating Scale (SRS), Disability Rating Scale (DRS), Revised Craig Handicap Assessment and Reporting Technique (R-CHART), and Glasgow Outcome Scale (GOS). The number of maximal scores on each of the surveys was studied to determine which instruments continued to reveal deficits years after TBI. RESULTS: Most individuals obtained maximum scores, ie, functional independence, on these scales: LCFS, FIM motor subscale and total score, R-CHART physical independence subscale, FIM+FAM, GOS, and the SRS. Measures with the fewest maximum scores (<36%, measuring deficits still extant in the group) were the R-CHART cognition subscale and the NFI memory/attention and communication subscales, and employment subscales. Items, subscales, and total scores that showed good variability and correlated most highly and frequently with other scales also demonstrating good variability were the PCRS, the DRS and FIM+FAM employment items, the R-CHART cognition subscale, and the NFI motor, memory/attention, communication, and depression subscales (the R-CHART cognition subscale and NFI memory/attention subscale were highly correlated with the PCRS;.84,.83). CONCLUSIONS: Measures that appeared to contribute little to assessing functional status of a TBI sample years postinjury were the FIM, FIM+FAM, SRS, GOS, and LCFS. Measures that showed a range of deficits across participants were DRS employability, the NFI, PCRS, and the R-CHART cognition subscale.     

Accelerometry: providing an integrated, practical method for long-term, ambulatory monitoring of human movement

Accelerometry offers a practical and low cost method of objectively monitoring human movements, and has particular applicability to the monitoring of free-living subjects. Accelerometers have been used to monitor a range of different movements, including gait, sit-to-stand transfers, postural sway and falls. They have also been used to measure physical activity levels and to identify and classify movements performed by subjects. This paper reviews the use of accelerometer-based systems in each of these areas. The scope and applicability of such systems in unsupervised monitoring of human movement are considered. The different systems and monitoring techniques can be integrated to provide a more comprehensive system that is suitable for measuring a range of different parameters in an unsupervised monitoring context with free-living subjects. An integrated approach is described in which a single, waist-mounted accelerometry system is used to monitor a range of different parameters of human movement in an unsupervised setting.     

Detection and monitoring of hypoxemia and oxygen therapy

Many techniques are available to evaluate oxygenation. These include arterial blood gases, capillary blood gases, point-of-care testing, blood gas monitors, pulse oximetery, transcutaneous blood gases, mixed venous blood gases, venous oximetry, and gastric tonometry. Clinicians should understand not only the benefits, but also the limitations of these techniques. Monitoring of oxygenation should not be done just because it is technically feasible. The decision to monitor, like any other clinical decision, should be based on therapeutic objectives.     

The demographics and economics of long-term oxygen therapy

Home oxygen therapy represents a scientifically validated and universally accepted therapeutic regimen for the treatment of chronic hypoxemia secondary to COPD. The clinical benefits of home oxygen, including a decrease in morbidity and often a concomitant increase in the quality of life have been repeatedly confirmed through rigorous worldwide trials, studies, and investigations. However, since home oxygen is an expensive treatment modality, important questions continue to be raised about the overall cost-benefit of the intervention. Such scrutiny is expected to continue, especially in the United States, as the entire issue of health care cost-containment remains atop the domestic political agenda. Providers of home oxygen therapy have traditionally realized quite favorable reimbursement for home oxygen equipment, especially for those patient-customers covered under the Medicare program. However, recent Medicare reimbursement reductions of more than 30% have raised serious questions about the ability of home oxygen providers, especially those with annual revenues less than $1 million, to sustain their historical high level of support services to home oxygen patient-customers. Of particular concern is the economic hardship of supplying portable oxygen, especially for those patient-customers with unusually high ambulatory needs. The use of oxygen-conserving devices is viewed by some as one strategy to better control the costs of supplying portable oxygen, although there are those who still question whether or not oxygen-conserving devices can effectively forestall arterial oxygen desaturation across the entire spectrum of ambulation. Given the evidence now being reported that compliance in using home oxygen as prescribed may well be much lower than originally believed, the time is probably right to revisit the role played by home oxygen providers in determining continuing need through the performance of periodic reassessments. Such reassessments, if designed according to prescribed and validated protocols and conducted by home respiratory therapists under orders of the prescribing physician, would be a valuable tool to ensure continued medical need and identifying noncompliance. This would help ensure that those needing and using home oxygen would continue to receive the benefit. At the same time, patient-customers who, for one reason or another, stop using their oxygen equipment despite repeated encouragement, would have the equipment removed. The net result would be that reimbursement dollars currently wasted on home oxygen equipment that is not being used could be reallocated for those patient-customers willing and able to use the equipment as prescribed.     

Assessing the need for and potential role of a day hospice: a qualitative study

We conducted a qualitative case study as part of a needs assessment for a day hospice in a small Ontario city. Data were gathered from semi-structured interviews with 28 stakeholders: nine health care administrators, 11 health care providers, and eight lay people (terminally ill adults and informal caregivers). Respondents described support, counselling, social activities, and respite as key day hospice services. They also described several barriers to accessing services, including location, transportation, admission criteria, referrals, and fees. For most respondents, the ideal staff mix includes both volunteers and paid professionals in either a free-standing organization or institutionally linked hospice. Although the vast majority of participants were reluctant to impose admission criteria or other limitations on hospice clientele, they expressed the need to ensure equitable access to this scarce resource. Opinions varied greatly across stakeholder groups, highlighting the need to collect information from all relevant stakeholder groups when planning hospices.     

Dynamic evaluation of near-infrared peripheral oximetry in healthy volunteers: A comparison between INVOS and EQUANOX

Purpose

The present study aimed to compare peripheral regional tissue oxygen saturation (rSO₂) values and desaturation/resaturation rates given by INVOS and EQUANOX devices.

Materials and methods

Twenty healthy volunteers were investigated during 4 experimental steps: baseline, hyperoxia, ischemia, and reperfusion. For each volunteer, 2 sensors INVOS and 2 sensors EQUANOX were placed on both left and right calves. Blood pressure, heart rate, and peripheral pulse oximetry were monitored.

Results

Peripheral rSO₂ ranged from 40% to 95% (INVOS) and from 47% to 100% (EQUANOX): 81 ± 12 vs 82 ± 9 (P = .469). A significant relationship was found at baseline between absolute values of INVOS and EQUANOX (n = 40; R² = 0.159; P = .011). Bias was − 0.4%, and limits of agreement were ± 15.1%. The percent maximum differences vs baseline values during dynamic maneuvers were 33% ± 19% (95% confidence interval, 24-42) and 21% ± 14% (95% confidence interval, 15-28) for INVOS and EQUANOX, respectively. No significant relationship was observed between percent maximum differences in INVOS and EQUANOX (n = 20; R² = 0.128; P = .122). Rates of desaturation/resaturation during occlusive vascular tests were 3.65% per minute vs 2.36% per minute (P = .027) and 30.42% per minute vs 16.28% per minute (P = .004) for INVOS and EQUANOX, respectively.

Conclusions

INVOS and EQUANOX are not comparable in measuring both absolute values and dynamic changes of peripheral rSO₂ and near-infrared spectroscopy–derived parameters during occlusion vascular tests.     

Effects of long-term oxygen therapy on mortality and morbidity

In general, based on the above studies of the effects of supplemental oxygen on reducing mortality and improving sleep and exercise function in certain patient groups, patients whose disease is stable on a full medical regimen with PaO2 < or = 55 mm Hg (SaO2 < or = 88%) should be considered for LTOT. Patients with PaO2 of 55-59 mm Hg with signs of tissue hypoxemia (i.e., cor pulmonale, polycythemia, impaired cognition) should also be considered for LTOT. Oxygen therapy should also be considered for those who desaturate during sleep or exercise. These guidelines have been adopted by Medicare as reimbursement criteria and have also been endorsed by the American Thoracic Society. Indications for LTOT endorsed by the American Thoracic Society and published in the "Standards for the Diagnosis and Care of Patients with COPD" are shown in Table 6. More research is required to investigate the use of supplemental oxygen in patients who suffer nocturnal desaturation but do not have signs of end organ dysfunction, those who have an improvement in dyspnea with supplemental oxygen, and in normoxemic patients with impaired exercise performance who improve while inspiring supplemental oxygen.