Oxygen Saturation In Patients Research Articles

The safety of patient‐controlled sedation

We have investigated the safety of a previously described method of patient-controlled sedation in 100 healthy patients presenting for elective surgery. The device used 0.33-ml boluses of propofol (10 mg.ml-1) infused over 6 s with no lockout. All patients attempted to put themselves to sleep by pressing a button on the hand-held device. The oxygen saturation, heart rate, sedation score and airway patency were noted every minute. When the patient stopped pressing the button, the anaesthetist took over the handset and continued pressing the button until the patient became unresponsive. The system allowed rapid sedation. Only five patients were still anxious after 2 min. After 3 min, no patient was still anxious and more than 70 patients had slurred speech. When they stopped pressing the button, 11 patients were judged oversedated, of whom two were unresponsive. One patient's oxygen saturation decreased transiently to 84%: no other patient's oxygen saturation decreased below 90%. There were no other significant changes. We conclude that the system studied works well but carries too high a risk of oversedation for unsupervised use.

Intraoperative Hypoxia from Nitrogen Tanks with Oxygen Fittings

Intraoperative Hypoxia from Nitrogen Tanks with Oxygen Fittings

Technical implementation and clinical findings/results of monitoring oxygen saturation in patients referred for long term EEG monitoring

Recent technical developments allow the recording of a patient's oxygen saturation (SpO 2) simultaneously with intensive long-term EEG monitoring (LTM). Clinically significant information from this enhanced multi-system physiological monitoring device can contribute to more accurate diagnoses in patients referred for LTM. This report covers the technical usage of combined SpO 2/EEG recordings in a small group of patients. Clinically, the findings on the SpO 2 monitor helped to define the diagnosis in many of these patients. In a few, the SpO 2 changes were diagnostic in their own right and prompted referral to our Sleep Disorders Laboratory. From a research aspect, the details of the morphology and timing of the oxygen desaturations and EEG show several interesting relationships with respect to the dynamics of seizure semiology and respiratory physiology.

Single-Lung Ventilation in a Patient with a Freshly Placed Percutaneous Tracheostomy

Various techniques have been described for providing single-lung ventilation in patients with a tracheostomy. Coe et al. [1] suggested placement of a double-lumen endotracheal tube through a tracheostomy site in 1984. Oxorn and Pagliarello [2] later described the use of a bronchial blocker (Fogarty catheter) inserted through a modified fiberoptic bronchoscope endotracheal tube adapter. More recently, Andros and Lennon [3] reported placement of a Univent Trademark tube (Fuji Systems Corp., Tokyo, Japan) through a tracheostomy site. We propose a simpler technique for single-lung ventilation in patients with either fresh or percutaneous tracheostomies. Importantly, this technique can be used in patients who require continuous ventilation during bronchial blocker placement. Case Report A 34-yr-old female was admitted to the hospital after sustaining major traumatic injury in a high-speed motor vehicle accident. Her injuries included cerebral contusion, open right humerus fracture, mesenteric hematoma, and right flail chest with massive right-sided pulmonary contusion. Initial treatment after stabilization included placement of an intracranial pressure (ICP) monitor, exploratory laparotomy for a positive diagnostic peritoneal lavage, and open reduction and internal fixation of the humerus fracture. Her postoperative course was significant for persistent fever and an unstable ICP that was exquisitely sensitive to fluctuations in PaCO (2). On the seventh day of hospitalization, an 8.0-mm Portex (Concord/Portex, Keene, NH) percutaneous tracheostomy tube was placed for long-term ventilation. The following day, a computerized tomographic scan revealed air fluid levels in the right lower lobe of her lung. She was scheduled for emergent resection of her right lower lobe. The patient was transported to the operating theater and ventilated via a Siemens model C ventilator (Siemens Elema AB, Solna, Sweden). A flexible bronchoscope adapter (Concord/Portex) was inserted between the tracheostomy tube and anesthesia circuit. General anesthesia was induced with intravenous thiopental and fentanyl. Rocuronium was administered for muscle relaxation. Direct laryngoscopy was performed, and the vocal cords were visualized. A lubricated bronchial blocker (Fogarty catheter) was passed between the vocal cords, and the cuff on the tracheostomy tube was temporarily deflated to allow passage of the catheter into the trachea. A pediatric flexible bronchoscope was then passed through the tracheostomy tube, and the bronchial blocker was guided into the right mainstem bronchus under direct visualization. The balloon on the catheter was placed at the take-off of the right upper lobe. When inflated, the concavity of the take-off held the balloon in place and allowed for isolation of the right lung. Single-lung ventilation was then attempted. The patient's oxygen saturation remained stable, but PaCO2 began to rise, precipitating an increase in ICP. The balloon on the bronchial blocker was deflated, and the blocker was advanced into the bronchus intermedius under direct visualization through the flexible bronchoscope. The balloon was then reinflated, and the right middle and lower lobes were successfully isolated. Despite adequate lung isolation and oxygenation, the patient's PaCO2 continued to increase, as did her ICP. Thus, single-lung ventilation was discontinued, and right lower lobectomy was completed without complication while ventilating both lungs. Discussion A fresh percutaneous tracheostomy in this patient limited options for single-lung ventilation. Placement of a double-lumen endotracheal tube or a Univent Trademark tube either orally or through the tracheostomy site would have required removal of the percutaneously placed tracheostomy tube and a formal surgical tracheostomy revision for tracheostomy tube replacement. Placement of a bronchial blocker via the fiberoptic bronchoscope port as described by Oxorn and Pagliarello [2] raised concerns about the ability to maintain ventilation during placement as well as the stability and potential air leak around a protruding catheter. The chosen method allowed for continuous ventilation and direct visualization of bronchial blocker placement without compromise of the fresh tracheostomy site or modification of existing equipment as suggested by Oxorn and Pagiarello [2]. Single-lung ventilation in a patient with a tracheostomy may be accomplished in a number of ways. Placing a bronchial blocker orally and positioning it under direct visualization with a flexible bronchoscope passed through the tracheostomy tube proved to be an easy, safe, and simple way to provide single-lung ventilation. Furthermore, this technique allowed for ventilation during positioning of the bronchial blocker with minimal disturbance to the tracheostomy site.

Venous air embolism related to the use of a pressure device for rapid blood transfusion

AbstractA 70 year old woman received a transfusion of packed red blood cells via the distal port of a subclavian central venous catheter. In order to facilitate flow, the blood pack was placed within a manually inflatable pressure bag. When the patient's oxygen saturation and systolic blood pressure fell precipitously, it was noticed that the blood pack was empty and that air was present along the entire length of the intravenous tubing. A provisional diagnosis of venous air embolism was made. Management consisted of positioning the woman head‐down in the left lateral decubitus position and ventilating with 100% oxygen. Air was unable to be aspirated from the affected central venous catheter port. Her condition improved and her subsequent intensive care unit course was uneventful.A pulmonary artery catheter recorded haemodynamic changes at the time of the venous air embolism. There was an initial increase in pulmonary artery pressure and central venous pressure, associated with a decrease in mean arterial pressure and oxygen saturation. Similar observations have been made in animal models of graded (infusion type) venous air embolism.The diagnosis of venous air embolism is generally clinical, aided by echocardiogram, end‐tidal carbon dioxide monitoring, pulse oximetry, chest radiography and haemodynamic monitoring. Current management of venous air embolism includes prevention of further air entry, positioning the patient head‐down in the left lateral decubitus position and administration of 100% oxygen. External cardiac massage, aspiration of air (via central venous catheter, pulmonary artery catheter or transcutaneously) and hyperbaric oxygen may also play a role.

Analgesia and sedation in interventional radiological procedures

The use of intravenous analgesia and anxiolytics in interventional radiology improves the patient's tolerance of potentially painful and prolonged procedures and allows the radiologist better control of the course of the procedure being undertaken. Monitoring of the patient's oxygen saturation, pulse rate, respiration, blood pressure and cardiac rhythm during a procedure is essential. Fentanyl and midazolam is a combination that is effective and convenient to use because both agents are relatively short acting, have little cardiovascular depression and are easily reversible (with naloxone and flumazenil). They are a better alternative to pethidine and diazepam because they can be more tightly titrated and controlled and are safer and more suitable for use in outpatients. Monitoring for respiratory depression is important and special care must be taken in the elderly and patients with hepatic, renal or chronic airways disease. General anaesthesia may be unavoidable in patients who are unstable, unco-operative or who have raised intracranial pressure.

Early response to pulse oximetry alarms with telemetry.

Twenty ICU patients were monitored for an average of 45 hr each, with both bedside and nursing station monitors, which were set to alarm audibly if the patient's oxygen saturation dropped below 90%. Bedside alarms alerted caregivers to 51 of the 74 hypoxemic events; central alarms alerted personnel to the other 23 events. The alarms led to a change in treatment in 35 of the 48 (73%) true desaturation episodes. We conclude that central oximetric monitoring may help with detection of arterial desaturation events even in a well-staffed ICU.