Supplemental oxygen impairs detection of hypoventilation by pulse oximetry

Accuracy of acoustic respiration rate monitoring in pediatric patients

BACKGROUND

Rainbow acoustic monitoring (RRa) utilizes acoustic technology to continuously and noninvasively determine respiratory rate from an adhesive sensor located on the neck.

OBJECTIVE

We sought to validate the accuracy of RRa, by comparing it to capnography, impedance pneumography, and to a reference method of counting breaths in postsurgical children.

METHODS

Continuous respiration rate data were recorded from RRa and capnography. In a subset of patients, intermittent respiration rate from thoracic impedance pneumography was also recorded. The reference method, counted respiratory rate by the retrospective analysis of the RRa, and capnographic waveforms while listening to recorded breath sounds were used to compare respiration rate of both capnography and RRa. Bias, precision, and limits of agreement of RRa compared with capnography and RRa and capnography compared with the reference method were calculated. Tolerance and reliability to the acoustic sensor and nasal cannula were also assessed.

RESULTS

Thirty-nine of 40 patients (97.5%) demonstrated good tolerance of the acoustic sensor, whereas 25 of 40 patients (62.5%) demonstrated good tolerance of the nasal cannula. Intermittent thoracic impedance produced erroneous respiratory rates (>50 b·min(-1) from the other methods) on 47% of occasions. The bias ± SD and limits of agreement were -0.30 ± 3.5 b·min(-1) and -7.3 to 6.6 b·min(-1) for RRa compared with capnography; -0.1 ± 2.5 b·min(-1) and -5.0 to 5.0 b·min(-1) for RRa compared with the reference method; and 0.2 ± 3.4 b·min(-1) and -6.8 to 6.7 b·min(-1) for capnography compared with the reference method.

CONCLUSIONS

When compared to nasal capnography, RRa showed good agreement and similar accuracy and precision but was better tolerated in postsurgical pediatric patients.

The OPERA trial - comparison of early nasal high flow oxygen therapy with standard care for prevention of postoperative hypoxemia after abdominal surgery: study protocol for a multicenter randomized controlled trial

BACKGROUND

Respiratory support following postoperative extubation is of major importance to prevent hypoxemia and subsequent respiratory failure and reintubation. High-flow nasal cannula oxygen (HFNC) delivers a flow-dependent positive airway pressure and improves oxygenation by increasing end-expiratory lung volume. Whether application of HFNC may have therapeutic advantages over conventional oxygen therapy for respiratory support in the early postextubation surgical period remains to be established.

METHODS/DESIGN

The Optiflow for prevention of post-extubation hypoxemia after abdominal surgery (OPERA) trial is an investigator-initiated multicenter randomized controlled two-arm trial with assessor-blinded outcome assessment, randomizing 220 patients with intermediate to high risk of pulmonary complications after abdominal surgery to receive HFNC or conventional oxygen therapy following extubation, stratified by the presence of epidural analgesia and center. The primary outcome measure is the percentage of patients with postoperative hypoxemia one hour after tracheal extubation. Secondary outcome measures are postoperative pulmonary complications, need for noninvasive ventilation and intubation for respiratory failure.

DISCUSSION

The OPERA trial is the first randomized controlled study powered to investigate whether early application of HFNC following extubation after abdominal surgery prevents against postoperative hypoxemia and pulmonary complications.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01887015.

[Nocturnal monitoring of home non-invasive ventilation: Contribution of simple tools such as pulse-oximetry, capnography, built-in ventilator software and autonomic markers of sleep fragmentation]

Complex respiratory events, which may have a detrimental effect on both quality of sleep and control of nocturnal hypoventilation, occur during sleep in patients treated by non-invasive ventilation (NIV). Among these events are patient-ventilator asynchrony, increases in upper airway resistance with or without increased respiratory drive, and leaks. Detection of these events is important in order to select the most appropriate ventilator settings and interface. Simple tools can provide important information when monitoring NIV. Pulse-oximetry is important to ensure that an adequate SpO2 is provided, and to detect either prolonged or short and recurrent desaturations. However, the specificity of pulse-oximetry tracings under NIV is low. Transcutaneous capnography discriminates between hypoxemia related to V/Q mismatch and hypoventilation, documents correction of nocturnal hypoventilation, and may detect ventilator-induced hyperventilation, a possible cause for central apnea/hypopnea and glottic closure. Data provided by ventilator software helps the clinician by estimating ventilation, tidal volume, leaks, rate of inspiratory or expiratory triggering by the patient, although further validation of these signals by independent studies is indicated. Finally, autonomic markers of sympathetic tone using signals such as pulse wave amplitude of the pulse-oximetry signal can provide reliable information of sleep fragmentation.

Using the Entropy of Tracheal Sounds to Detect Apnea during Sedation in Healthy Nonobese Volunteers

Background:

Undetected apnea can lead to severe hypoxia, bradycardia, and cardiac arrest. Tracheal sounds entropy has been proved to be a robust method for estimating respiratory flow, thus maybe a more reliable way to detect obstructive and central apnea during sedation.

Methods:

A secondary analysis of a previous pharmacodynamics study was conducted. Twenty volunteers received propofol and remifentinal until they became unresponsive to the insertion of a bougie into the esophagus. Respiratory flow rate and tracheal sounds were recorded using a pneumotachometer and a microphone. The logarithm of the tracheal sound Shannon entropy (Log-E) was calculated to estimate flow rate. An adaptive Log-E threshold was used to distinguish between the presence of normal breath and apnea. Apnea detected from tracheal sounds was compared to the apnea detected from respiratory flow rate.

Results:

The volunteers stopped breathing for 15 s or longer (apnea) 322 times during the 12.9-h study. Apnea was correctly detected 310 times from both the tracheal sounds and the respiratory flow. Periods of apnea were not detected by the tracheal sounds 12 times. The absence of tracheal sounds was falsely detected as apnea 89 times. Normal breathing was detected correctly 1,196 times. The acoustic method detected obstructive and central apnea in sedated volunteers with 95% sensitivity and 92% specificity.

Conclusions:

We found that the entropy of the acoustic signal from a microphone placed over the trachea may reliably provide an early warning of the onset of obstructive and central apnea in volunteers under sedation.

Early adjuvant use of nonopioids associated with reduced odds of serious postoperative opioid adverse events and need for rescue in children

OBJECTIVES

Examine factors associated with opioid adverse drug events (ADE) in children.

SPECIFIC AIMS

Examine whether adjuvant nonopioid use is associated with a decreased probability of opioid-ADEs and need for rescue.

BACKGROUND

Opioid-ADEs contribute to serious preventable harm for hospitalized children. Adjuvant nonopioid use may mitigate opioid risk postoperatively, yet few studies support this notion.

METHOD

This nested case-control study included children who required intervention or rescue from opioid-ADEs and procedure-matched controls. Data were recorded from medical records and primary outcomes included serious opioid-ADEs (over-sedation and respiratory depression) and need for rescue (e.g., naloxone, rapid response team). Hierarchical logistic regression (HLR) models examined relationships between factors and opioid-ADEs. Early clinical signs and symptoms of deterioration were examined.

RESULTS

Twenty five children with opioid-ADEs and 98 children without events were included. ASA-PS remained an independent risk factor (odds ratio, 2.56 [1.09, 6.03]; P = 0.031), while adjuvant nonopioids a risk reduction factor for opioid-ADEs (OR, 0.16 [0.05, 0.47]; P = 0.001) and need for rescue (0.14 [0.04, 0.47]; P = 0.001). Supplemental oxygen use at PACU discharge was associated with an increased odds of opioid-ADEs (OR, 3.72 [1.35, 10.23]; P = 0.007) and need for rescue (5.5 [1.7, 17.82]; P = 0.002).

CONCLUSIONS

Findings from this study suggest that strategies such as early use of adjuvant nonopioids may reduce risk of opioid-ADEs postoperatively. Furthermore, children who require supplemental oxygen early postoperatively may be at heightened risk of later events.

Inspiratory-resistive loading increases the ventilatory response to arousal but does not reduce genioglossus muscle activity on the return to sleep

Arousals from sleep are thought to predispose to obstructive sleep apnea by causing hyperventilation and hypocapnia, which reduce airway dilator muscle activity on the return to sleep. However, prior studies of auditory arousals have not resulted in reduced genioglossus muscle activity [GG-electromyogram (EMG)], potentially because airway resistance prior to arousal was low, leading to a small ventilatory response to arousal and minimal hypocapnia. Thus we aimed to increase the ventilatory response to arousal by resistive loading prior to auditory arousal and determine whether reduced GG-EMG occurred on the return to sleep. Eighteen healthy young men and women were recruited. Subjects were instrumented with a nasal mask with a pneumotachograph, an epiglottic pressure catheter, and intramuscular GG-EMG electrodes. Mask CO2 levels were monitored. Three- to 15-s arousals from sleep were induced with auditory tones after resting breathing (No-Load) or inspiratory-resistive loading (Load; average 8.4 cmH2O·l−1·s−1). Peak minute ventilation following arousal was greater after Load than No-Load (mean ± SE; 8.0 ± 0.6 vs. 7.4 ± 0.6 l/min, respectively). However, the nadir end tidal partial pressure of CO2 did not differ between Load conditions (43.1 ± 0.6 and 42.8 ± 0.5 mmHg, respectively), and no period of reduced GG activity occurred following the return to sleep (GG-EMG baseline, minimum after Load and No-Load = 2.9 ± 1.2%, 3.1 ± 1.3%, and 3.0 ± 1.3% max, respectively). These findings indicate that the hyperventilation, which occurs following tone-induced arousal, is appropriate for the prevailing level of respiratory drive, because loading did not induce marked hypocapnia or lower GG muscle activity on the return to sleep. Whether similar findings occur following obstructive events in patients remains to be determined.

Critical care in the ED: potentially fatal asthma and acute lung injury syndrome

Emergency department clinicians are frequently called upon to assess, diagnose, and stabilize patients who present with acute respiratory failure. This review describes a rapid initial approach to acute respiratory failure in adults, illustrated by two common examples: (1) an airway disease - acute potentially fatal asthma, and (2) a pulmonary parenchymal disease - acute lung injury/acute respiratory distress syndrome. As such patients are usually admitted to hospital, discussion will be focused on those initial management aspects most relevant to the emergency department clinician.

Difficult Airway Society Guidelines for the management of tracheal extubation

Tracheal extubation is a high-risk phase of anaesthesia. The majority of problems that occur during extubation and emergence are of a minor nature, but a small and significant number may result in injury or death. The need for a strategy incorporating extubation is mentioned in several international airway management guidelines, but the subject is not discussed in detail, and the emphasis has been on extubation of the patient with a difficult airway. The Difficult Airway Society has developed guidelines for the safe management of tracheal extubation in adult peri-operative practice. The guidelines discuss the problems arising during extubation and recovery and promote a strategic, stepwise approach to extubation. They emphasise the importance of planning and preparation, and include practical techniques for use in clinical practice and recommendations for post-extubation care.

Procedural sedation with propofol for painful orthopaedic manipulation in the emergency department expedites patient management compared with a midazolam/ketamine regimen: a randomized prospective study

BACKGROUND

The use of procedural sedation and analgesia to allow painful orthopaedic manipulations in the emergency department has become a standard practice over the last decade. Both propofol and midazolam/ketamine are attractive sedative regimens for routine use in the emergency department. We hypothesized that sedation with propofol as compared with midazolam/ketamine will save time in the emergency department. The purpose of the present study was to compare the recovery time, the total sedation time, and the adverse events of procedural sedation and analgesia induced with propofol as compared with midazolam/ketamine.

METHODS

This prospective randomized study was conducted in the emergency department of a tertiary care, university-affiliated medical center. All sedations and orthopaedic manipulations were performed by trained and approved orthopaedic residents assisted by a registered nurse according to the same protocol. Sedation time and adverse events were recorded in real time.

RESULTS

Sixty adults (thirty-five men and twenty-five women) with a mean age (and standard deviation) of 45 ± 17 years were randomly enrolled in the study, with thirty patients being managed with each regimen. The average recovery time was 7.8 ± 3.7 minutes following sedation with propofol, compared with 30.7 ± 10.1 minutes following sedation with midazolam/ketamine (p < 0.001). The average total sedation time was 16.2 ± 3.8 minutes for the propofol group, compared with 41.6 ± 10.7 minutes for the midazolam/ketamine group (p < 0.001). The overall rate of respiratory and hemodynamic adverse events was 20% for the propofol group and 10% for the midazolam/ketamine group.

CONCLUSIONS

The use of propofol for an orthopaedic procedure requiring sedation in the emergency department expedites patient management and saves time in comparison with the use of midazolam/ketamine.

Pulse oximetry in pediatric practice

The introduction of pulse oximetry in clinical practice has allowed for simple, noninvasive, and reasonably accurate estimation of arterial oxygen saturation. Pulse oximetry is routinely used in the emergency department, the pediatric ward, and in pediatric intensive and perioperative care. However, clinically relevant principles and inherent limitations of the method are not always well understood by health care professionals caring for children. The calculation of the percentage of arterial oxyhemoglobin is based on the distinct characteristics of light absorption in the red and infrared spectra by oxygenated versus deoxygenated hemoglobin and takes advantage of the variation in light absorption caused by the pulsatility of arterial blood. Computation of oxygen saturation is achieved with the use of calibration algorithms. Safe use of pulse oximetry requires knowledge of its limitations, which include motion artifacts, poor perfusion at the site of measurement, irregular rhythms, ambient light or electromagnetic interference, skin pigmentation, nail polish, calibration assumptions, probe positioning, time lag in detecting hypoxic events, venous pulsation, intravenous dyes, and presence of abnormal hemoglobin molecules. In this review we describe the physiologic principles and limitations of pulse oximetry, discuss normal values, and highlight its importance in common pediatric diseases, in which the principle mechanism of hypoxemia is ventilation/perfusion mismatch (eg, asthma exacerbation, acute bronchiolitis, pneumonia) versus hypoventilation (eg, laryngotracheitis, vocal cord dysfunction, foreign-body aspiration in the larynx or trachea). Additional technologic advancements in pulse oximetry and its incorporation into evidence-based clinical algorithms will improve the efficiency of the method in daily pediatric practice.

Sedation and monitoring for gastrointestinal endoscopy: A nationwide web survey in Italy

BACKGROUND

Best strategy of sedation/analgesia in gastrointestinal (GI) endoscopy is still debated.

AIMS OF THE STUDY

To evaluate sedation and monitoring practice among Italian gastroenterologists and to assess their opinion about non-anaesthesiologist propofol administration.

METHODS

A 19-item survey was mailed to all 1192 members of the Italian Society of Digestive Endoscopy (SIED). For each respondent were recorded demographic data, medical specialty, years of practise and practise setting.

RESULTS

A total of 494 SIED members returned questionnaires, representing a response rate of 41.4%. The most employed sedation pattern was benzodiazepines for oesophagogastroduodenoscopies (EGDS) in 50.8% of procedures, benzodiazepines plus opioids for colonoscopy and enteroscopy in 39.5% and 35.3% of procedures, respectively, propofol for endoscopic retrograde colangiopancreatography (ERCP) and endoscopic ultrasound (EUS) in 42.3% and 35.6% of procedures, respectively. With regard to propofol use, 66% respondents stated that propofol was exclusively administered by anaesthesiologists. However, 76.9% respondents would consider non-anaesthesiologist propofol administration after appropriate training. Pulse oximetry is the most employed system for procedural monitoring. Supplemental O(2) is routinely administered by 39.3% respondents.

CONCLUSIONS

Use of sedation has become a standard practise during GI endoscopy in Italy. Pattern varies for each type of procedure. Pulse oximetry is the most employed system of monitoring. Administration of propofol is still directed by anaesthesiologists.

Adverse events during monitored anesthesia care for GI endoscopy: an 8-year experience

BACKGROUND

The importance of sedation during endoscopy is well established. There is no consensus about the best techniques for sedation, which specialist should perform it, and in which location.

OBJECTIVE

To provide data on the epidemiology of adverse events during sedation for endoscopy.

DESIGN

Retrospective analysis of a prospective database.

SETTING

Endoscopy unit of a university hospital.

PROCEDURES

A total of 17,999 procedures performed over 8 years.

INTERVENTIONS

Sedation for GI endoscopy.

MAIN OUTCOME MEASUREMENTS

We recorded the following information: sex, age, body mass index, smoking habits, American Society of Anesthesiologists and Mallampati scores, duration of the procedure, type of sedative drug administered, whether the procedure was performed emergently, and endoscopic interventions during the maneuver. Adverse events were defined as occurrences that warranted intervention and were classified as hypotension, desaturation, bradycardia, hypertension, arrhythmia, aspiration, respiratory depression, vomiting, cardiac arrest, respiratory arrest, angina, hypoglycemia, and/or allergic reaction.

RESULTS

Deep sedation with intravenous propofol target controlled infusion pump was the most frequently used means of administering sedation. Adverse events were rare in both the adult (4.5%) and pediatric (2.6%) populations. Six complications occurred in more than 0.1% of adult cases: arterial hypotension, desaturation, bradycardia, arterial hypertension, arrhythmia, and aspiration. Only bradycardia (2.1%) and hypotension (0.44%) occurred in children. Three adult patients (0.017%) died, and no pediatric patients died. Some predictive models for the occurrence of complications are proposed.

LIMITATIONS

Retrospective analysis, single-center data collection.

CONCLUSIONS

Deep sedation during endoscopic procedures is safe in both adults and children. Our data may be useful for the future planning of new clinical strategies in this setting.

Evaluation of the SEDline to improve the safety and efficiency of conscious sedation

Brain function monitors have improved safety and efficiency in general anesthesia; however, they have not been adequately tested for guiding conscious sedation for periodontal surgical procedures. This study evaluated the patient state index (PSI) obtained from the SEDline monitor (Sedline Inc., San Diego, CA) to determine its capacity to improve the safety and efficiency of intravenous conscious sedation during outpatient periodontal surgery. Twenty-one patients at the periodontics clinic of Baylor College of Dentistry were admitted to the study in 2009 and sedated to a moderate level using midazolam and fentanyl during periodontal surgery. The PSI monitoring was blinded from the clinician, and the following data were collected: vital signs, Ramsay sedation scale (RSS), medications administered, adverse events, PSI, electroencephalography, and the patients' perspective through visual analogue scales. The data were correlated to evaluate the PSI's ability to assess the level of sedation. Results showed that the RSS and PSI did not correlate (r = -0.25) unless high values associated with electromyographical (EMG) activity were corrected (r = -0.47). Oxygen desaturation did not correlate with the PSI (r = -0.08). Satisfaction (r = -0.57) and amnesia (r = -0.55) both increased as the average PSI decreased. In conclusion, within the limits of this study, PSI appears to correlate with amnesia, allowing a practitioner to titrate medications to that effect. It did not provide advance warning of adverse events and had inherent inaccuracies due to EMG activity during oral surgery. The PSI has the potential to increase safety and efficiency in conscious sedation but requires further development to eliminate EMG activity from confounding the score.

How best to approach endoscopic sedation?

Sedation is the drug-induced reduction of a patient's consciousness. The aim of sedation in endoscopic procedures is to increase the patient's comfort and to improve endoscopic performance, especially in therapeutic procedures. The most commonly used sedation regimen for conscious sedation in gastrointestinal endoscopy is still the combination of benzodiazepines with opioids. However, the use of propofol has increased enormously in the past decade and several studies show advantages of propofol over the traditional regimes in terms of faster recovery time. It is important to be aware that the complication rate of endoscopies increases when sedation is used; therefore, a thorough risk evaluation before the procedure and monitoring during the procedure must be performed. In addition, properly trained staff and emergency equipment should be available. The best approach to sedation in endoscopy is to choose a sedation regimen for the individual patient, tailored according to the clinical risk assessment and the anxiety level of the patient, as well as to the type of planned endoscopic procedure.

Supplementary oxygen for nonhypoxemic patients: O2 much of a good thing?

Supplementary oxygen is routinely administered to patients, even those with adequate oxygen saturations, in the belief that it increases oxygen delivery. But oxygen delivery depends not just on arterial oxygen content but also on perfusion. It is not widely recognized that hyperoxia causes vasoconstriction, either directly or through hyperoxia-induced hypocapnia. If perfusion decreases more than arterial oxygen content increases during hyperoxia, then regional oxygen delivery decreases. This mechanism, and not (just) that attributed to reactive oxygen species, is likely to contribute to the worse outcomes in patients given high-concentration oxygen in the treatment of myocardial infarction, in postcardiac arrest, in stroke, in neonatal resuscitation and in the critically ill. The mechanism may also contribute to the increased risk of mortality in acute exacerbations of chronic obstructive pulmonary disease, in which worsening respiratory failure plays a predominant role. To avoid these effects, hyperoxia and hypocapnia should be avoided, with oxygen administered only to patients with evidence of hypoxemia and at a dose that relieves hypoxemia without causing hyperoxia.

Nurse-administered procedural sedation and analgesia in the cardiac catheter laboratory: an integrative review

OBJECTIVES

To identify and appraise the literature concerning nurse-administered procedural sedation and analgesia in the cardiac catheter laboratory.

DESIGN AND DATA SOURCES

An integrative review method was chosen for this study. MEDLINE and CINAHL databases as well as The Cochrane Database of Systematic Reviews and the Joanna Briggs Institute were searched. Nineteen research articles and three clinical guidelines were identified.

RESULTS

The authors of each study reported nurse-administered sedation in the CCL is safe due to the low incidence of complications. However, a higher percentage of deeply sedated patients were reported to experience complications than moderately sedated patients. To confound this issue, one clinical guideline permits deep sedation without an anaesthetist present, while others recommend against it. All clinical guidelines recommend nurses are educated about sedation concepts. Other findings focus on pain and discomfort and the cost-savings of nurse-administered sedation, which are associated with forgoing anaesthetic services.

CONCLUSIONS

Practice is varied due to limitations in the evidence and inconsistent clinical practice guidelines. Therefore, recommendations for research and practice have been made. Research topics include determining how and in which circumstances capnography can be used in the CCL, discerning the economic impact of sedation-related complications and developing a set of objectives for nursing education about sedation. For practice, if deep sedation is administered without an anaesthetist present, it is essential nurses are adequately trained and have access to vital equipment such as capnography to monitor ventilation because deeply sedated patients are more likely to experience complications related to sedation. These initiatives will go some way to ensuring patients receiving nurse-administered procedural sedation and analgesia for a procedure in the cardiac catheter laboratory are cared for using consistent, safe and evidence-based practices.

Patterns of unexpected in-hospital deaths: a root cause analysis

BACKGROUND

Respiratory alarm monitoring and rapid response team alerts on hospital general floors are based on detection of simple numeric threshold breaches. Although some uncontrolled observation trials in select patient populations have been encouraging, randomized controlled trials suggest that this simplistic approach may not reduce the unexpected death rate in this complex environment. The purpose of this review is to examine the history and scientific basis for threshold alarms and to compare thresholds with the actual pathophysiologic patterns of evolving death which must be timely detected.

METHODS

The Pubmed database was searched for articles relating to methods for triggering rapid response teams and respiratory alarms and these were contrasted with the fundamental timed pathophysiologic patterns of death which evolve due to sepsis, congestive heart failure, pulmonary embolism, hypoventilation, narcotic overdose, and sleep apnea.

RESULTS

In contrast to the simplicity of the numeric threshold breach method of generating alerts, the actual patterns of evolving death are complex and do not share common features until near death. On hospital general floors, unexpected clinical instability leading to death often progresses along three distinct patterns which can be designated as Types I, II and III. Type I is a pattern comprised of hyperventilation compensated respiratory failure typical of congestive heart failure and sepsis. Here, early hyperventilation and respiratory alkalosis can conceal the onset of instability. Type II is the pattern of classic CO2 narcosis. Type III occurs only during sleep and is a pattern of ventilation and SPO2 cycling caused by instability of ventilation and/or upper airway control followed by precipitous and fatal oxygen desaturation if arousal failure is induced by narcotics and/or sedation.

CONCLUSION

The traditional threshold breach method of detecting instability on hospital wards was not scientifically derived; explaining the failure of threshold based monitoring and rapid response team activation in randomized trials. Furthermore, the thresholds themselves are arbitrary and capricious. There are three common fundamental pathophysiologic patterns of unexpected hospital death. These patterns are too complex for early detection by any unifying numeric threshold. New methods and technologies which detect and identify the actual patterns of evolving death should be investigated.

Anesthetic considerations and surgical caveats for awake airway surgery

The evolution of novel techniques for the treatment of laryngeal pathology has led to a significant expansion of the role of diagnostic assessment and the range of laryngeal procedures performed. These procedures typically benefit from an anesthetic approach that diverges from a standard general endotracheal or laryngeal mask airway-based inhalational anesthetic. The shared airway, need for intraoperative assessment of vocal cord function, risk of airway fire, and desire for rapid emergence and discharge are all important factors. In this article the authors undertake a collaborative anesthesia-surgical discussion of anesthetic management for airway procedures that are optimally performed with a spontaneously breathing, cooperative patient. An overview of pharmacologic approaches to airway anesthesia and cooperative sedation, followed by a discussion on the surgical requirements and anesthetic goals of commonly performed procedures, are presented.

Transcutaneous carbon dioxide in severe COPD patients during bronchoscopic lung volume reduction

BACKGROUND

Patients undergoing bronchoscopy are usually monitored only by pulse oximetry, hence hypoventilation cannot be assessed. Transcutaneous carbon dioxide tension (TcPCO(2)) monitoring is a non-invasive technique to assess hypoventilation. Patients with severe chronic obstructive pulmonary disease (COPD) undergoing bronchoscopy are at increased risk for sedation-induced hypoventilation. The aim of the study was to measure TcPCO(2) using a digital sensor to examine the occurrence of hypoventilation during bronchoscopic lung volume reduction (BLVR).

METHODS

Combined TcPCO(2) and SpO(2) saturation and arterial blood gases (ABG) were prospectively measured in 15 patients with severe COPD (Mean FEV(1) 29%) undergoing BLVR under conscious sedation with IV midazolam and IV alfentanil.

RESULTS

A highly significant correlation was noted between simultaneous ABG PCO(2) samplings and TcPCO(2) measured (R = 0.85, p < 0.001). Mean baseline TcPCO(2) level was 41.7 ± 10.3 mm Hg (±SD) (range 35-66 mmHg)], and peak measurement during the procedure was 61 ± 17.1 mm Hg (range 41-111 mmHg). The mean increase in TcPCO(2) during bronchoscopy was 19.2 (range 3.7-45 mmHg) [p < 0.0001]. Mean duration of significant hypercapnea (TcPCO(2) > 55 mmHg), observed in 7 (46%) patients, was 9 min (range 0-53).

CONCLUSIONS

Bronchoscopy performed under conscious sedation in patients with severe COPD is frequently associated with significant hypoventilation that can only be detected by TcPCO(2) monitoring. Combined measurement of SpO(2) and TcPCO(2) during bronchoscopy enhances patient safety, helps guide administration of sedation, and can alert physicians to the need for anesthesia reversal following completion of bronchoscopic interventions.

Sedation issues in quality colonoscopy

The subject of endoscopic sedation for colonoscopy remains controversial because of unresolved questions concerning the relative benefits, risks, and cost of service. There is also disagreement about the most appropriate sedation drug(s), delegation of responsibility for drug administration, and patient monitoring. This article examines recent trends in endoscopic sedation; the impact of sedation on the quality, safety, and patient tolerability of colonoscopy; and reviews the economic implications of current sedation practices.

Sedation: not quite that simple

The number of diagnostic and therapeutic interventions performed under sedation is growing rapidly. While providing patients with an improved experience secondary to anxiolysis, analgesia, and amnesia, sedation also puts them at risk for associated cardiorespiratory and other complications. Several medications are available for sedation, all of which have unique advantages and disadvantages. The combination of patient characteristics, procedural factors, and side effects associated with each medication places each patient at risk and therefore, vigilance during sedation cannot be overemphasized. Due vigilance includes proper monitoring, training, staffing, and equipment, all of which are essential to the safe delivery of sedation.

[Why and how to diagnose sleep respiratory disorders?]

Gas exchange abnormalities occur firstly during sleep in restrictive and obstructive chronic respiratory failure. Nocturnal hypoxemia is often a revealing feature of a sleep-related hypoventilation/hypoxemia syndrome in patients who will have later a diurnal hypoxemia. On the other hand, sleep may induce breathing abnormalities in individuals without lung diseases, like in obstructive sleep apnea syndrome (OSAS). In OSAS, repeated closure and/or narrowing of the pharynx during sleep increases the inspiratory effort and induces sleep fragmentation. Intermittent hypoxemia is another consequence of the obstructive events in OSAS. Besides its direct consequences on sleep, OSAS is also associated with an increased risk of cardiovascular morbi-mortality. Reduced daytime alertness and cognitive functions are usually present in patients with sleep-disordered breathing. These features are believed to be related to both sleep fragmentation and nocturnal hypoxia/hypercapnia. Sleep-related hypoventilation/hypoxemia and pharyngeal obstructive events may occur together in patients with respiratory insufficiency, especially in obese and/or chronic obstructive pulmonary disease (COPD) subjects. A correct qualitative and quantitative assessment of sleep-disordered breathing may only be performed by recording specific physiological signals during sleep.

Respiratory monitoring: physiological and technical considerations

The American Dental Association and several dental specialty organizations have published guidelines that detail requirements for monitoring patients during various levels of sedation and, in some cases, general anesthesia. In general, all these are consistent with those guidelines suggested by the American Society of Anesthesiologists for sedation and analgesia by nonanesthesiologists. It is well accepted that the principal negative impact of sedation and anesthesia is the compromise of respiratory function. While monitoring per se is a technical issue, an appreciation of its purpose and the interpretation of the information provided require an understanding of respiratory anatomy and physiology. The focus of this continuing education article is to address the physiological aspects of respiration and to understand the appropriate use of monitors, including the interpretation of the information they provide.

Human patient simulation and its role in endoscopic sedation training

Patient simulation is now considered to be a valid method for the education and evaluation of providers of sedation. Using full-scale human simulators to provide a realistic setting, participants can acquire skills for patient monitoring, administration of sedation medications, and the recognition and management of critical events. Although obstacles to its implementation exist, it appears likely that simulation training will become an integral part of training for providers of procedural sedation.

Patient monitoring during gastrointestinal endoscopy: why, when, and how?

Patient monitoring is intended to reduce the risk of sedation-related cardiopulmonary complications. Physiological monitoring and visual assessment by a qualified individual should be routine during endoscopic procedures. Additionally, ventilatory monitoring should be considered for high-risk patients and those receiving sedation with propofol.