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PubMed1993

Effects of fentanyl versus sufentanil in equianesthetic doses on middle cerebral artery blood flow velocity.

BACKGROUND: Sufentanil has been reported to increase cerebral blood flow in comparison with fentanyl. However, because of the use of animal models, supraclinical doses and/or background anesthetic agents, the clinical applicability of these studies remains difficult to assess. Therefore, transcranial Doppler ultrasonography was used to determine the cerebral hemodynamic effects of equianesthetic doses of fentanyl and sufentanil on middle cerebral artery (MCA) blood flow velocity in patients without intracranial pathologic conditions. METHODS: Twenty-four unpremedicated American Society of Anesthesiologists physical status 1 and 2 patients undergoing elective nonintracranial neurosurgery were assigned randomly to receive equipotent blinded infusions of either sufentanil (15 micrograms/min) or fentanyl (150 micrograms/min) for anesthetic induction during spontaneous ventilation of 100% oxygen. Normocapnia, as measured by infrared capnography, was maintained by manually assisting ventilation, as necessary. The cerebral opioid effect was quantified using the spectral edge frequency parameter. The infusion was continued until either 1) spectral edge frequency decreased below 10 Hz or 2) 150 micrograms of sufentanil or 1,500 micrograms of fentanyl was infused, whichever occurred first. On average, the patients received 1.7 +/- 0.55 micrograms/kg or 16 +/- 4 micrograms/kg of sufentanil or fentanyl, respectively. The right MCA mean, peak systolic, and peak diastolic velocities and pulsatility index were measured continuously by transcranial Doppler ultrasonography. RESULTS: The mean arterial pressure decreased slightly in both groups, but only in the fentanyl group were the changes significant. The MCA velocity increased by approximately 25% in both groups. However, the relative changes in MCA velocity were not different between groups. The pulsatility indexes were unchanged in both groups. CONCLUSIONS: These data suggest that, at clinically relevant doses in the absence of other drugs, cerebral blood flow velocity is increased by both fentanyl and sufentanil. Furthermore, there appears to be no significant differences in the cerebral hemodynamic profiles of the two drugs, as assessed by transcranial Doppler ultrasonography.

Adolescent↗
PubMed1996

Intraabdominal carbon dioxide insufflation in the pregnant ewe. Uterine blood flow, intraamniotic pressure, and cardiopulmonary effects.

BACKGROUND: Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation. METHODS: In a prospective randomized cross-over study, nine ewes were to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or receive no insufflation (n = 9; control group). Anesthesia was induced with thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guided by serial maternal arterial blood gas analysis to maintain PaCO2 between 35 and 40 mmHg. Data from insufflated animals were collected during insufflation (60 min) and after desufflation (30 min). Control group data were collected and matched to similar time intervals for 90 min. Ewes were allowed to recover, and after a rest period (48 h) they were entered in the cross-over study. RESULTS: During insufflation there was a significant increase (P < 0.05) in maternal PaCO2 to end-tidal carbon dioxide gradient and minute ventilation, with concomitant decreases in maternal end-tidal carbon dioxide and PaO2. Intraamniotic pressure increased significantly during insufflation. No significant changes were observed in maternal hemodynamic variables, fetal variables, or in uterine blood flow during the study. There were no fetal deaths or preterm labor in any of the animals during the experiment. CONCLUSIONS: During the 1-h insufflation, a marked increase in PaCO2-to-end-tidal carbon dioxide gradient was observed, suggesting that capnography may be an inadequate guide to ventilation during carbon dioxide pneumoperitoneum in the pregnant patient. No other significant circulatory changes were observed.

Amnion↗
PubMed1997

Adverse anesthetic outcomes arising from gas delivery equipment: a closed claims analysis.

BACKGROUND: Anesthesia gas delivery equipment is a potentially important source of patient injury. To better define the contribution of gas delivery equipment to professional liability in anesthesia, the authors conducted an in-depth analysis of cases from the database of the American Society of Anesthesiologists Closed Claims Project. METHODS: The database of the Closed Claims Project is composed of closed US malpractice claims that have been collected in a standardized manner. All claims resulting from the use of gas delivery equipment were reviewed for recurrent patterns of injury. RESULTS: Gas delivery equipment was associated with 72 (2%) of 3,791 claims in the database. Death and permanent brain damage accounted for almost all adverse outcomes (n = 55, 76%). Equipment misuse was defined as fault or human error associated with the preparation, maintenance, or deployment of a medical device. Equipment failure was defined as unexpected malfunction of a medical device, despite routine maintenance and previous uneventful use. Misuse of equipment (n = 54, 75%) was three times more common than equipment failure (n = 17, 24%). Misconnects and disconnects of the breathing circuit made the largest contribution to injury (n = 25, 35%). Reviewers judged that 38 of 72 claims (53%) could have been prevented by pulse oximetry, capnography, or a combination of these two monitors. Overall, 56 of 72 gas delivery claims (78%) were deemed preventable with the use or better use of monitors. The year of occurrence for claims involving gas delivery equipment ranged from 1962 to 1991 and did not differ significantly from claims involving other adverse respiratory events. CONCLUSIONS: Claims associated with gas delivery equipment are infrequent but severe and continue to occur in the 1990s. Educational and preventive strategies that focus on equipment misuse and breathing circuit configuration may have the greatest potential for enhancing the safety of anesthesia gas delivery equipment.

Anesthesiology↗
PubMed2000

Acoustic reflectometry profiles of endotracheal and esophageal intubation.

BACKGROUND: Acoustic reflectometry can be used to create a "one-dimensional image" of a cavity, such as the airway and lung, with the image displayed as an area-length curve. This pilot study was undertaken to determine whether acoustic reflectometry could be used to distinguish between an endotracheal and an esophageal intubation. METHODS: Ten adult patients underwent general endotracheal anesthesia and neuromuscular blockade. The reflectometer wavetube was attached to an endotracheal tube, and a reflectometric profile was obtained of the endotracheal tube and the airway and lung cavity. After confirmation of tracheal intubation, a second endotracheal tube was placed in the esophagus. After four breaths were administered, a reflectometric profile of the endotracheal tube-esophagus cavity was obtained. RESULTS: The acoustic reflectometric profiles for tracheal and esophageal intubation profiles were distinctive and characteristic. For an endotracheal tube-airway cavity, the profile shows a constant cross-sectional area throughout the length of the endotracheal tube, followed by a rapid rise in the area past the carina. For an esophageal intubation, the profile shows constant cross-sectional area throughout the length of the endotracheal tube, followed by a sudden decrease in the cross-sectional area to zero. CONCLUSIONS: In this pilot study, acoustic reflectometry within seconds, and without resort to capnography, was able to generate characteristic and distinctive area-length profiles for both endotracheal and esophageal intubation. Acoustic reflectometry may have a role in the emergency imaging of the airway, and in the immediate detection of esophageal intubations, particularly in cases of cardiopulmonary arrest in which the usual techniques for confirmation of breathing tube placement fail.

Acoustics↗
PubMed2004

Antichemical protective gear prolongs time to successful airway management: a randomized, crossover study in humans.

BACKGROUND: Airway management is the first step in resuscitation. The extraordinary conditions in mass casualty situations impose special difficulties in airway management, even for experienced caregivers. The authors evaluated whether wearing surgical attire or antichemical protective gear made any difference in anesthetists' success of airway control with either an endotracheal tube or a laryngeal mask airway. METHODS: Fifteen anesthetists with 2-5 yr of residency and wearing either full antichemical protective gear or surgical attire intubated or inserted laryngeal masks in 60 anesthetized patients. The study was performed in a prospective, randomized, crossover manner. The duration of intubation/insertion was measured from the time the device was grasped to the time a normal capnography recording was obtained. RESULTS: Endotracheal tubes were introduced significantly (P < 0.01) faster when the anesthetist wore surgical attire (31 +/- 7 vs. 54 +/- 24 s for protective gear), but the mean times necessary to successfully insert laryngeal masks were similar (44 +/- 20 s for surgical attire vs. 39 +/- 11 s for protective gear). Neither performance failure nor incidences of hypoxemia were recorded. CONCLUSIONS: This first report in humans shows to what extent anesthetists' wearing of antichemical protective gear slows the time to intubate but not to insert a laryngeal mask airway compared with wearing surgical attire. Laryngeal mask airway insertion is faster than tracheal intubation when wearing protective gear, indicating its advantage for airway management when anesthetists wear antichemical protective gear. If chances for rapid and successful tracheal intubation under such chaotic conditions are poor, laryngeal mask airway insertion is a viable choice for airway management until a proper secured airway is obtainable.

Adult↗
PubMed2004

Laryngeal mask airway insertion by anesthetists and nonanesthetists wearing unconventional protective gear: a prospective, randomized, crossover study in humans.

BACKGROUND: Mass casualty situations impose special difficulties in airway management, even for experienced caregivers. The laryngeal mask airway is part of the difficult airway algorithm. The authors evaluated the success rate and the time to secure airways by mask by anesthetists, surgeons, and novices when wearing either surgical attire or full antichemical protective gear that included butyl rubber gloves and a filtering antigas mask. METHODS: Twenty anesthetists and 22 surgeons with 2-5 yr of residency inserted a laryngeal mask airway in 84 anesthetized patients, and 6 novices repetitively inserted masks in 57 patients under both conditions in a prospective, randomized, crossover manner. The duration of insertion was measured from the time the device was first grasped until a normal capnography recording was obtained. RESULTS: Anesthetists needed 39 +/- 14 s to insert the masks when wearing surgical attire and 40 +/- 12 s with protective gear. In contrast, surgery residents needed 64 +/- 40 and 102 +/- 40 s (P = 0.0001), respectively. Anesthetists inserted masks in a single attempt, whereas the surgeons needed up to four attempts with no hypoxia or failure associated. The initial attire-wearing novices' insertions took as long as the surgeons'; three of them then reached the mean performance time of the anesthetists after four (protective gear) and two (surgical attire) trials, with only one occurrence of hypoxia and a failure rate similar to that of the surgeons. CONCLUSIONS: Anesthesia residents insert laryngeal mask airways at a similar speed when wearing surgical attire or limiting antichemical protective gear and two to three times faster than surgical residents or novices wearing either outfit. Novices initially perform at the level of surgical residents, but their learning curve was quick under both conditions.

Adult↗
PubMed2006

Injury and liability associated with monitored anesthesia care: a closed claims analysis.

BACKGROUND: To assess the patterns of injury and liability associated with monitored anesthesia care (MAC) compared with general and regional anesthesia, the authors reviewed closed malpractice claims in the American Society of Anesthesiologists Closed Claims Database since 1990. METHODS: All surgical anesthesia claims associated with MAC (n = 121) were compared with those associated with general (n = 1,519) and regional (n = 312) anesthesia. A detailed analysis of MAC claims was performed to identify causative mechanisms and liability patterns. RESULTS: MAC claims involved older and sicker patients compared with general anesthesia claims (P < 0.025), often undergoing elective eye surgery (21%) or facial plastic surgery (26%). More than 40% of claims associated with MAC involved death or permanent brain damage, similar to general anesthesia claims. In contrast, the proportion of regional anesthesia claims with death or permanent brain damage was less (P < 0.01). Respiratory depression, after absolute or relative overdose of sedative or opioid drugs, was the most common (21%, n = 25) specific damaging mechanism in MAC claims. Nearly half of these claims were judged as preventable by better monitoring, including capnography, improved vigilance, or audible alarms. On-the-patient operating room fires, from the use of electrocautery, in the presence of supplemental oxygen during facial surgery, resulted in burn injuries in 20 MAC claims (17%). CONCLUSION: Oversedation leading to respiratory depression was an important mechanism of patient injuries during MAC. Appropriate use of monitoring, vigilance, and early resuscitation could have prevented many of these injuries. Awareness and avoidance of the fire triad (oxidizer, fuel, and ignition source) is essential to prevent on-the-patient fires.

Adolescent↗
PubMed1990

Prediction of outcome of cardiopulmonary resuscitation from end-tidal carbon dioxide concentration.

Capnography is a valuable tool in the management of cardiac arrest, since end-tidal CO2 (PetCO2) correlates well with cardiac output and there are no other suitable noninvasive ways to measure this important variable during resuscitation. Animal studies also suggest that PetCO2 correlates well with the likelihood of resuscitation, but this has never been confirmed in humans. We prospectively studied 55 adult, nontraumatic prehospital cardiac arrest patients. PetCO2 was monitored with an in-line sensor on arrival in the ED and throughout the arrest, which was managed by the usual advanced cardiac life-support treatment guidelines. Chest compression was carried out mechanically. Patients were assessed for return of spontaneous pulse as evidence of initial resuscitation; hospital discharge and long-term survival were not examined. Fourteen patients developed spontaneous pulses and were resuscitated, and 41 were not. The length and aggressiveness of treatment and CPR were not different between the two groups, nor were there differences in down time, resuscitation time, or other factors known to affect outcome. Patients who developed a pulse had a mean PetCO2 of 19 +/- 14 (SD) torr at the start of resuscitation, and those who did not had a mean PetCO2 of 5 +/- 4 torr (p less than .0001). This difference was significant both in nonperfusing rhythms (asystole and ventricular fibrillation) and in potentially perfusing rhythms (electromechanical dissociation). An initial PetCO2 of 15 torr correctly predicted eventual return of pulse with a sensitivity of 71%, a specificity of 98%, a positive predictive value of 91%, and a negative predictive value of 91%. A receiver operating curve was generated for sensitivity and specificity of the test at varying PetCO2 thresholds.

Aged↗
PubMed2000

Deadspace to tidal volume ratio predicts successful extubation in infants and children.

OBJECTIVE: Using a modification of the Bohr equation, single-breath carbon dioxide capnography is a noninvasive technology for calculating physiologic dead space (V(D)/V(T)). The objective of this study was to identify a minimal V(D)/V(T) value for predicting successful extubation from mechanical ventilation in pediatric patients. DESIGN: Prospective, blinded, clinical study. SETTING: Medical and surgical pediatric intensive care unit of a university hospital. PATIENTS: Intubated children ranging in age from 1 wk to 18 yrs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Forty-five patients were identified by the pediatric intensive care unit clinical team as meeting criteria for extubation. Thirty minutes before the planned extubation, each patient was begun on pressure support ventilation set to deliver an exhaled tidal volume of 6 mL/kg. After 20 mins on pressure support ventilation, an arterial blood gas was obtained, V(D)/V(T) was calculated, and the patient was extubated. Over the next 48 hrs, the clinical team managed the patient without knowledge of the preextubation V(D)/V(T) value. Of the 45 patients studied, 25 had V(D)/V(T) < or =0.50. Of these patients, 24 of 25 (96%) were successfully extubated without needing additional ventilatory support. In an intermediate group of patients with V(D)/V(T) between 0.50 and 0.65, six of ten patients (60%) successfully extubated from mechanical ventilation. However, only two of ten patients (20%) with a V(D)/V(T) > or =0.65 were successfully extubated. Logistic regression analysis revealed a significant association between lower V(D)/V(T) and successful extubation. CONCLUSIONS: A V(D)/V(T) < or =0.50 reliably predicts successful extubation, whereas a V(D)/V(T) >0.65 identifies patients at risk for respiratory failure following extubation. There appears to be an intermediate V(D)/V(T) range (0.51-0.65) that is less predictive of successful extubation. Routine V(D)/V(T) monitoring of pediatric patients may permit earlier extubation and reduce unexpected extubation failures.

Adolescent↗
PubMed2002

Expanding automatic external defibrillators to include automated detection of cardiac, respiratory, and cardiorespiratory arrest.

The new Guidelines of the American Heart Association state that lay rescuers can no longer rely on the manual pulse check to confirm cardiac arrest in an unresponsive patient. We were therefore prompted to develop a method for automated determination of the presence or absence of cardiac contraction and breathing. The technique was designed to be incorporated into conventional automated external defibrillators and to work in conjunction with the information derived from rhythm analyses by the automated defibrillator. Using conventional electrocardiographic sensing and defibrillation electrodes, the transthoracic impedance was measured by passing a constant amplitude alternating current of 5 mA through the thorax at a frequency of 35 kHz. In five anesthetized male domestic swine, we observed pulses that were coincident with cardiac contraction documented by esophageal echocardiography. In addition, we observed larger signals of lower frequency that were time related to ventilation and documented by capnography. Both signals disappeared after inducing ventricular fibrillation. The impedance measurement identified respiratory arrest in anesthetized animals and primary cardiac arrest after ventricular fibrillation was induced. The cardiac arrest detector is therefore likely to augment the current information provided by automated defibrillators and to allow for more precise verbal prompting of lay rescuers.

Animals↗
PubMed1996

Intraoperative end-tidal carbon dioxide levels and derived calculations correlated with outcome in trauma patients.

BACKGROUND: To determine the relationship between the prognosis of seriously injured patients requiring emergency surgery and intraoperative end-tidal CO2 variables and "excess Pco2." METHOD: Retrospective chart review of 100 seriously injured patients admitted to Detroit Receiving Hospital and requiring major surgery (mortality rate of 40%). Standard intraoperative monitoring, including continuous capnography, plus arterial blood analyses every 15 to 30 minutes during surgery. RESULTS: After resuscitation for 45 to 90 minutes, 11 patients had a systolic blood pressure < 100 mm Hg and, of these patients, 10 (91%) died. Of the remaining 89 patients, mortality rates were 53% (16/30), with an end-tidal CO2 of 22 mm Hg or less, versus 24% (14/59) with an end-tidal CO2 of 23 mm Hg or more (p = 0.011). An arterial to end-tidal Pco2 difference of 13 mm Hg or more after resuscitation was associated with an increased mortality rate (50% (20/34 vs. 18% (20/55)) (p < 0.005). The mortality rate was particularly high, with a final arterial to end-tidal Pco2 difference of 12 mm Hg or more (73% (30/41) versus 17% (10/59) (p < 0.001). A final Paco2 excess (i.e., the amount by which the Paco2 was higher than expected from the bicarbonate) > 1.0 mm Hg was also associated with an increased mortality rate ((62% (33/53) vs. 15% (7/47)) (p < 0.001). CONCLUSION: Values derived from the end-tidal CO2 and the excess Pco2 should be monitored intraoperatively in critically injured patients. Efforts should be made to improve cardiac output and adjust ventilation to maintain an end-tidal Pco2 of 25 mm Hg or more, an arterial to end-tidal CO2 difference of 12 mm Hg or less, and an excess Paco2 of 1.0 mm Hg or less.

Adult↗
PubMed1997

The effects of fentanyl and sufentanil on cerebral hemodynamics.

Our study investigated the effects of moderate doses of fentanyl and sufentanil versus high-dose sufentanil on cerebral hemodynamics by using transcranial Doppler ultrasonography (TCD). Thirty American Society of Anesthesiologists (ASA) II and III patients scheduled for elective coronary artery bypass graft (CABG) were studied after Institutional Review Board (IRB) approval and informed consent. The evening before surgery, all patients received oral flurazepam (1 mg/kg), Atropine (0.4 mg/70 kg s.c.) and a combination of droperidol (70 micrograms/kg s.c.) plus fentanyl (1.5 micrograms/kg s.c.) were given as preanesthetic medication 1 h before induction of anesthesia. Anesthesia was induced with either 25 micrograms/kg fentanyl i.v. (group 1, n = 10), 3 micrograms/kg sufentanil i.v. (group 2, n = 10) or 6 micrograms/kg sufentanil i.v. (group 3, n = 10). All patients received 100 micrograms/kg pancuronium i.v. With the induction of respiratory depression, assisted ventilation was performed followed by controlled ventilation to maintain normoxia and normocapnia (FiO2, 1.0). Cerebral blood flow velocity (CBFV, cm/s) was measured continuously in the middle cerebral artery by using a bidirectional 2-MHz TCD system. Monitoring included heart rate (HR, beats/min), direct mean arterial blood pressure (MAP, mm Hg), and PaCO2. Physiologic variables including arterial blood gases were measured at baseline, 5 min, and 10 min after infusion of fentanyl or sufentanil. In all patients, HR, MAP, end-tidal carbon dioxide tension (PetCO2), and PaCO2 were constant over time and did not differ between groups. CBFV did not change with moderate doses of fentanyl (group 1) or sufentanil (group 2). In contrast, infusion of high-dose sufentanil (group 3) was associated with 27 to 30% decreases in CBFV (p < 0.05). Our results suggest that sufentanil decreases CBFV in a dose-related fashion with a threshold effect. Increases in CBFV and CBF seen in previous studies may be related to an increasing PaCO2 when maintenance of normocarbia is based on only real-time capnography with a constant PetCo2 rather than additional arterial blood gas monitoring.

Analgesics, Opioid↗
PubMed2002

Should one rely on capnometry when a capnogram is not seen?

Capnography is one of the basic monitoring techniques in day-to-day anesthesia practice that provides information not only regarding the patient's ventilation, circulation, and metabolism, but also regarding proper functioning of a closed-circle system. The authors report a case in which after endotracheal intubation the end-tidal capnometric reading rose very high, but the capnogram was not seen on the monitor. The unexpectedly high capnometric reading with absent waveform during intermittent positive pressure ventilation without any apparent cause and consequent delayed institution of corrective measures resulted in severe brain bulge. There was severe hypercarbia as a result of a malfunctioning expiratory unidirectional valve that allowed rebreathing. Retrospective retrieval of data showed that a fraction of inspired carbon dioxide was also high and the baseline was raised beyond the usual range of 0 to 40 mm Hg, giving the impression of an absent waveform on the existing scale. In conclusion, one should keep in mind the possibility of expiratory valve malfunction resulting from dislodgment while wheeling the anesthesia machine, the view becoming obscured as a result of condensation of water vapor on the under surface of the plastic case, and one should rely on the capnometric reading unless proved otherwise. Thus, one can prevent potential hazards of rebreathing.

Adult↗
PubMed2003

The anaesthesiologist in the intensive care unit.

PURPOSE OF REVIEW: This review focuses on recent knowledge in areas of anaesthesia expertise which are indispensable to intensive care unit management, including airway management, vascular access, regional analgesia and the treatment of status asthmaticus and status epilepticus. RECENT FINDINGS: Etomidate as the sole agent for intubation in the intensive care unit has a 90% success rate, while in a prehospital setting, the addition of succinylcholine to etomidate results in a 99% success rate. In determining successful intubation, capnography and laryngoscopic/fibreoptic visualization are superior to auscultation, while auscultation is as effective as the self-inflating bulb or transillumination with the lightwand. The dorsalis pedis artery is an effective alternative to radial artery cannulation, while arterial cannulation itself can result in major adverse effects if complications arise. Ultrasound guidance in the placement of central catheters results in an improved insertion success rate. Internal jugular and subclavian lines have similar risk of haemothorax or pneumothorax, while subclavian lines are associated with the lowest incidence of infection. Midazolam, thiopentone and propofol have all been found to be efficacious in terminating refractory status epilepticus, with thiopentone resulting in a lower incidence of breakthrough seizures or treatment failure but an increased incidence of hypotension. Inhalational anaesthesia using isoflurane or desflurane has also been found to be successful in refractory status epilepticus. In the management of status asthmaticus, limiting minute volume while tolerating hypercapnia and acidosis as well as the use of inhalational anesthesia have proven effective strategies in a number of refractory cases. SUMMARY: The anaesthesiologist's unique knowledge and skills are ideally suited to the practical management of patients in a critical care setting as well as in the treatment of the critical phases of many illnesses.

Journal Article↗
PubMed2005

Pediatric sedation outside the operating room: the year in review.

PURPOSE OF REVIEW: This review is a survey of the recent literature concerning issues and trends in the rapidly changing field of pediatric sedation. RECENT FINDINGS: Clinical guidelines for the safe provision of sedation to children continue to be developed and revised. Systems for providing sedation are evolving, and the most successful models emerging are those that involve a dedicated team, either mobile or stationary, of physicians and nurses. A variety of drugs is used, and potent drugs that were designed as anesthetics, such as propofol and ketamine, are being administered outside the operating room by anesthesiologists and non-anesthesiologists. The safety of this practice continues to be debated. The reported incidence of adverse events is different in various settings and systems; however, outcome data are difficult to compare because of differences in study design and outcome definition. There is agreement that sedation is a continuum, and evidence that the depth of sedation attained during procedural sedation in children is often consistent with general anesthesia. Capnography and processed electroencephalogram monitoring have been described in sedation studies, may enhance safety during pediatric sedation, and should be investigated further. SUMMARY: The evolution of systems, drugs, and monitors for the provision of pediatric sedation is continuing. An accurate assessment of safety and other outcomes will be enhanced through the establishment of multicenter collaborative databases.

Journal Article↗
PubMed2003

Stroke volumes and end-tidal carbon dioxide generated by precordial compression during ventricular fibrillation.

OBJECTIVE: The objective of this study was to measure stroke volumes produced by precordial compression during cardiopulmonary resuscitation and to quantitate relationships of stroke volume to measurements of end-tidal carbon dioxide. DESIGN: A prospective, observational animal study. SETTING: Medical research laboratory in a university-affiliated research and educational foundation. SUBJECTS: Domestic pigs. INTERVENTIONS: Eighteen anesthetized male, domestic pigs weighing between 40 and 45 kg were investigated. Ventricular fibrillation was electrically induced and continued for intervals ranging from 4 to 10 mins. Precordial compression was maintained at 80 per minute together with mechanical ventilation after endotracheal intubation. MEASUREMENTS AND MAIN RESULTS: Stroke volumes were measured with the aid of transesophageal echocardiographic imaging. End-tidal carbon dioxide was quantitated with conventional capnography. Baseline values of thermodilution cardiac output were highly correlated with echocardiographic measurements (r =.92). The stroke volume index produced by precordial compression averaged 0.45 mL/kg or approximately 37% of the average prearrest value of 1.22 mL/kg. The end-tidal carbon dioxide was highly predictive of stroke volume index (r =.88, p <.001) with a mean bias of 0.003 mL/kg. CONCLUSIONS: We confirmed that precordial compression produces approximately one third of prearrest stroke volumes during cardiopulmonary resuscitation and demonstrated that end-tidal carbon dioxide was quantitatively predictive of stroke volume index estimated by transesophageal echocardiographic imaging.

Animals↗
PubMed2004

Targeted resuscitation strategies after injury.

PURPOSE OF REVIEW: The management of the traumatically injured patient has evolved during the past half century despite continually high morbidity and mortality rates. The management of the trauma victim requires timely intervention and damage control in an attempt to maintain normal hemodynamic parameters and adequate systemic perfusion. There is a fine balance between oxygen delivery and consumption, and when this is perturbed, oxygen debt may ensue. The presence of ongoing oxygen debt is rather deleterious, resulting in an inflammatory cascade that can lead to multisystem organ dysfunction. The rapid identification and restoration of oxygen debt are central to the resuscitation of the critically ill patient, be it the result of sepsis or trauma. RECENT FINDINGS: Resuscitation end points have evolved that allow the physician to more rapidly identify a perturbation between oxygen delivery and consumption. Moreover, end points allow uniformity in gauging the adequacy of resuscitation: preventing under- and overresuscitation and serving as a basis to compare outcome measures in resuscitation trials. Recent technologic advances have allowed a greater wealth of clinical data that can be obtained via less invasive means. Examples of this include esophageal Doppler monitoring, sublingual capnography, orthogonal polarization spectral imaging, and lithium dilution cardiac output determinations. These devices can be used in concert with more traditional resuscitation end points (ie, lactate and base deficit) to maximize oxygen delivery and correct tissue dysoxia. In addition, the management of hemorrhagic shock is continuing to evolve and challenge the dogmatic practices of normotensive resuscitation. SUMMARY: This review addresses (1) resuscitation end points to optimize cardiac function, (2) resuscitation end points to assess the microcirculation, (3) recent developments in the management of hypotensive hemorrhagic shock, and (4) the translation of early goal-directed therapy from septic shock to use in trauma. Past findings are reflected on and direction for future investigation and clinical practice based on recent clinical advances is provided.

Acidosis↗
PubMed2005

Recent developments in percutaneous tracheostomy: improving techniques and expanding roles.

PURPOSE OF REVIEW: The purpose of this review is to provide an update of recent developments pertaining to the use of percutaneous tracheostomy. Percutaneous tracheostomy has been established as an alternative to open surgical tracheostomy, but many key questions about the optimal use of this procedure remain unanswered. RECENT FINDINGS: Issues in percutaneous tracheostomy that have been addressed in the recent literature include the optimal method, timing, use of percutaneous tracheostomy in emergencies, safety in high-risk populations, confirmation of tracheal puncture, and outcomes. SUMMARY: Recent literature suggests that percutaneous tracheostomy is safe to use in an expanding population of patients, including patients with airway compromise and thrombocytopenia. Several methods seem to be safe alternatives to that originally described. Capnography has arisen as an alternative to bronchoscopy for confirmation of tracheal puncture. Recent evidence highlights that although tracheostomy may improve short-term outcome, these critically ill patients have a significant long-term risk of poor outcome. This must be taken into consideration when this procedure is offered.

Emergency Medicine↗