A comparison of three variable performance devices for postoperative oxygen therapy

Influence of jet nebulization and oxygen delivery on the fraction of inspired oxygen: an experimental model

BACKGROUND

The fraction of inspired oxygen (FiO(2)) during oxygen-driven jet nebulization is unknown. In the case of air-driven jet nebulization, oxygen is often added through a nasal device, and again, the FiO(2) is unknown. The aim of this experimental study was to measure FiO(2) during oxygen- and air-driven jet nebulization, oxygen being added through a nasal device, and to compare the values observed with those measured during standard oxygen therapy.

METHODS

An endotracheal tube was inserted into the distal tracheal extremity of a cadaveric head and neck specimen and connected to a pump, simulating different respiratory patterns. FiO(2) was measured using an electrochemical oxygen analyzer under different nebulization and oxygen delivery conditions. Variables were compared using canonical analysis and analysis of simple and multiple variance.

RESULTS

FiO(2) was significantly influenced by the mode of oxygen delivery (p = 0.001). The highest FiO(2) was observed when oxygen was delivered via a nasopharyngeal catheter associated with air-driven jet nebulization. For oxygen flow rates of 12 and 15 L/min, a nasal cannula combined with air-driven jet nebulization resulted in a similar FiO(2). The FiO(2) was significantly lower in the case of oxygen-driven jet nebulization. The FiO(2) decreased with increasing respiratory rate (p < 0.001) and tidal volume (p < 0.001).

CONCLUSIONS

Oxygen delivery through a nasal device during air-driven jet nebulization significantly increases the FiO(2), whereas oxygen-driven jet nebulization dramatically decreases FiO(2) compared with standard oxygen therapy.

Comparison of nasal cannulas and the OxyArm in patients requiring chronic domiciliary oxygen therapy

OBJECTIVES

The present study was designed to compare the performance of a new oxygen delivery device, the OxyArm (OA) (Southmedic Inc, Canada), with a standard nasal cannula (NC) (Salter-Style 1600, Salter Labs, USA) for both oxygen delivery and patient preference in patients on long-term oxygen therapy (LTOT).

DESIGN AND SETTING

Randomized crossover study conducted in an outpatient setting.

PATIENTS AND METHODS

Twenty-five clinically stable LTOT patients were randomly assigned to an oxygen device (NC or OA) sequence. The baseline saturation level was determined, and patients were then treated at oxygen flow rates of 2 L/min, 3 L/min, 4 L/min, 5 L/min, 6 L/min and 7 L/min for 10 min each while at rest. Patients were then crossed over to the second device and the procedure was repeated. Oximetry values were then obtained following a 5 min walk test using the same device sequence. Lastly, the patients were sent home for a four-week home OA trial, after which, they filled out a questionnaire.

RESULTS

This sample of patients was primarily elderly ex-smokers with severe chronic obstructive pulmonary disease on oxygen therapy for the majority of the day. The primary findings were that the OA and NC were equally effective in delivering oxygen to patients and maintaining their oxygen saturation at both rest (P = 0.82) and during a 5 min walk test (P = 0.83). A patient's personal experience and comfort were identified as the most important factors in deciding on an oxygen device. Most patients felt that the OA was most suited for oxygen therapy while at rest.

CONCLUSIONS

The OA proved to be similar to the NC in delivering oxygen and maintaining saturation in patients on LTOT. The OA is one of the few alternatives to using NCs for these patients and, with its current design, appears to be most suited for resting conditions.

Binasal cannula versus face mask for oxygen therapy in patients with chronic pulmonary disease

Oxygen therapy, which is ordered frequently for patients with chronic pulmonary disease, remains a cornerstone of modern medical practice. This study was conducted to compare the efficiency and comfort of a binasal cannula versus a face mask during oxygen therapy. Sixty hypoxemic patients participated in this randomized controlled study. While each patient was hypoxemic, arterial blood gas analysis was performed before oxygen supplementation was begun. Arterial oxygen saturation was continuously monitored during oxygen therapy with a face mask or a binasal cannula. Subjects were allowed to return to their oxygen saturation level in room air before the device for oxygen treatment was changed. The same procedure was then repeated with the other device. Patient comfort was evaluated through the use of a questionnaire that was completed after each treatment period. The mean age+/-standard deviation was 62+/-13 y. No statistically significant difference was noted in oxygen saturation levels achieved with the 2 devices. The binasal cannula reached target oxygen levels (P=.007) more quickly than the face mask. The binasal cannula was reported to be significantly more comfortable (P=.0001), and had significantly fewer reports of dyspnea and restlessness, and was less of a nuisance (P=.019, P=.0001, and P=.0001, respectively). The binasal cannula was preferred for oxygen therapy by 71% of study patients. Although the efficiency of the 2 devices did not differ remarkably, the binasal cannula was regarded as a more comfortable and time-saving device for delivery of oxygen therapy to hypoxic patients.

Nasopharyngeal oxygen (NPO) as a safe and comfortable alternative to face mask oxygen therapy

Nasopharyngeal oxygen (NPO) therapy is an emerging alternative to conventional face mask oxygen administration. It warrants consideration for treating hypoxaemia when face mask therapy is impractical or when patient intolerance or non-compliance regularly interrupt treatment. The effectiveness of the NPO route has been validated in post anaesthetic care and paediatric intensive care units (PICUs), but use in the adult ICU remains minimal. Recent research in the adult ICU setting has shown the nasopharyngeal route to be as effective as face mask oxygen administration in alleviating mild to moderate hypoxaemia, and is significantly more comfortable for patients. Therefore, NPO, administered via a fine catheter advanced into the nasopharynx, should be considered when face masks (FMs) or nasal prongs (NPs) are impractical or poorly tolerated and, because of its effectiveness and improved comfort, in patients for whom traditional non-invasive oxygen therapy is indicated. Implications for resource utilisation and costs also exist.

Design of oxygen delivery systems influences both effectiveness and comfort in adult volunteers

PURPOSE

The aim of this investigation was to compare the efficiency of four oxygen delivery systems in healthy volunteers.

METHODS

The subjects received oxygen at flow rates of 3.0 and 5.0 L*min(-1) via a face mask, nasal cannulae, and two kinds of new open- and microphone-type oxygen delivery systems (OxyArm(TM) and Mike Cannula) in a random sequence, and values of partial arterial pressures of oxygen (PaO(2)) were measured. The comfort of these devices was also evaluated.

RESULTS

A significant, oxygen flow dependent increase in PaO(2) was obtained with all devices tested. PaO(2) was significantly higher when the face mask was used [217.5 +/- 19.9 (mean +/- SD) mmHg at 5 L*min(-1)) than when the Mike Cannula was used (177.5 +/- 14.8 mmHg). The face mask was the least comfortable and OxyArm was the most comfortable among the devices tested.

CONCLUSION

The results of our evaluation suggest that comfort and clinical performance should be considered when using oxygen delivery devices for patients who require oxygen supplementation.

Are nasal spectacles adequate for supplementary oxygen in patients after anaesthesia?

Two methods of oxygen delivery were compared when used postoperatively after a general anaesthetic had been administered. There were 255 patients randomly allocated to receive oxygen via nasal spectacles or a Hudson face mask in the initial postoperative period. Oxygen saturation was monitored using pulse oximetry. Seven percent of patients who received the Hudson mask and 14% of patients who received nasal spectacles desaturated below 94% (P = 0.10). Age, weight or American Society of Anesthesiologists (ASA) status did not predict oxygen desaturation; however, desaturation occurred more frequently in male patients with nasal spectacles undergoing abdominal surgery. If male patients who had abdominal surgery with muscle relaxants are excluded from the nasal spectacle group, the desaturation incidences for spectacles and masks are similar (10% versus 7%, P = 0.38). Using nasal spectacles for all postoperative oxygen therapy in selected patients is therefore feasible and could provide substantial cost-saving.

Postoperative oxygen therapy

Much has been published in the medical literature concerning adverse events relating to the surgical patient. Among the notable disorders requiring the expertise of the postanesthesia care unit nurse are the diagnosis and management of respiratory dysfunction acutely attributable to the effects of surgery and anesthesia. Inhalational and/or intravenous anesthetic agents contribute to pathophysiological alterations that lend to the development of hypoxemia in the postoperative period. When patients present with preexisting respiratory disease, their care is frequently more complex and challenging. This review session will address the oxygenation component of respiration and the perioperative influences that alter it as well as treatment considerations for normalizing oxygenation.

Evaluation of five oxygen delivery devices in spontaneously breathing subjects by oxygraphy

Oxygen supply systems may be divided into constant and variable performance systems. As the variable performance systems are widely used, it is relevant to investigate the variation in performance between devices and the influence of oxygen supply on the inspired oxygen fraction. Data were collected from 10 healthy volunteers during the use of one constant performance system and four variable performance systems at different gas flows and inspired oxygen fractions. A thin sampling catheter was placed in the nasopharynx to allow the measurement of the end-tidal oxygen fraction. When oxygen was supplied to variable performance systems, end-tidal oxygen fraction values measured in this way varied less and were more easily quantifiable than inspired oxygen fraction. End-tidal oxygen fraction was used to calculate inspired oxygen fraction. With the variable performance systems, inspired oxygen fraction varied considerably between subjects whereas a constant and equal rise was found for each subject with the fixed performance system. A large nasal catheter was capable of delivering the highest inspired oxygen fraction, whereas the Venturi mask delivered the most precise inspired oxygen fraction. We found oxygraphy useful in the interpretation of measurements made in patients receiving unknown inspired fractions of oxygen.