Decrease In End-tidal Carbon Dioxide Research Articles

ROLE OF CAPNOGRAPHY IN SAFE SEDATION OF VITRECTOMY PATIENTS

Purpose: To evaluate the efficiency of the capnography monitoring added to routine monitoring on oxygen desaturation, hypoxemia, and other vital parameters. Methods: 100 adult patients who had elective vitrectomy under sedation were included in this study. Patients were divided into “experiment”(capnography added to routine monitoring) and “control”(capnography not added to routine monitoring) groups. Hypoxemia, desaturation, tachycardia, bradycardia, additional maneuvers for the airway were compared. Increase and decrease in end-tidal carbon dioxide (EtCO2) levels, hypoxemia, desaturation, Integrated Pulmonary Index (IPI) levels requiring attention (5-7), and intervention (1-4) were determined in the experiment group, and frequencies of them were assessed. Results: Desaturation and bradycardia rates and counts in the experiment group were significantly lower than the control group. No significant difference was seen between groups in terms of hypoxemia, tachycardia, and additional maneuvers. 76%(38/50) of experiment group patients had decrease in EtCO2, 10%(5/50) increase in EtCO2, 38%(19/50) apnea, 52%(26/50) IPI levels requiring attention, 14%(7/50) IPI levels requiring intervention. Conclusion: With addition of the capnography to routine monitoring of sedated vitrectomy patients, oxygen desaturation and bradycardia can be less likely to occur, and with instant follow-up of the EtCO2, apnea, and IPI levels; respiratory depression can be recognized before oxygen desaturation develops.

Remaining Vigilant to Paradoxical Air Embolism in Patients Undergoing Hysteroscopic Surgery: A Case Report and Review of the Literature

The purpose of this case study and review was to understand the perianesthestic care of paradoxical air embolism (PAE) in patients undergoing hysteroscopic surgery. The perianesthestic management record of a patient undergoing hysteroscopic surgery was analyzed to study the characteristics of PAE, and the literature describing the perianesthestic care for PAE was reviewed. The first symptom of PAE in hysteroscopic surgery is often a decrease in end-tidal carbon dioxide (ETCO2), and the complications include embolism of the pulmonary artery, coronary artery, and cerebral artery. The best monitoring method is continuous ETCO2 monitoring, and intraoperative echocardiography is an excellent method to diagnose and guide the treatment of PAE. PAE is a rare but serious complication of hysteroscopic surgery that is associated with organ ischemia and hypoxia. Prevention and treatment of PAE requires the vigilance and cooperation of not only perianesthesia nurses and anesthesiologists but also the surgeons and operating room nurses. Early prevention, proper monitoring, and effective treatment are the keys to successful rescue for PAE.

Hyperventilation as a Predictor of Blood Donation-Related Vasovagal Symptoms.

Most of the research on vasovagal reactions has focused on the contributions of cardiovascular activity to the development of symptoms. However, other research suggests that additional mechanisms like hyperventilation may contribute to the process. The goal of the present investigation was to examine the influences of cardiovascular and respiratory variables on vasovagal symptoms. This study was part of a randomized controlled trial investigating the effects of behavioral techniques on the prevention of vasovagal reactions in blood donors. Data from the no-treatment control group were analyzed. The final sample was composed of 160 college and university students. Observational and self-report measures of symptoms were obtained. Physiological variables were measured mainly using respiratory capnometry. Although respiration rate remained stable throughout donation, change in end-tidal carbon dioxide was associated with requiring treatment for a reaction during donation (odds ratio = 0.57, 95% confidence interval [CI] = 0.41 to 0.79, p = .001) and self-reported symptoms measured in the postdonation period using the Blood Donation Reactions Inventory (β = -0.152, 95% CI = -0.28 to -0.02, t = -2.32, p = .022). Individuals with higher levels of predonation anxiety displayed larger decreases in end-tidal carbon dioxide throughout the procedure (F(2,236) = 3.64, p = .043, ηp = 0.030). Blood Donation Reactions Inventory scores were related to changes in systolic (β = -0.022, 95% CI = -0.04 to -0.004, t = -2.39, p = .019) and diastolic blood pressure (β = -0.038, 95% CI = -0.06 to -0.02, t = -4.03, p < .001). Although the vasovagal reaction has traditionally been viewed as a primarily cardiovascular event, the present results suggest that hyperventilation also plays a role in the development of vasovagal symptoms.

Respiratory and hemodynamic contributions to emotion-related pre-syncopal vasovagal symptoms

Vasovagal reactions are conventionally understood as resulting from systemic changes in cardiovascular activity; however, there exists a complementary perspective focused on specific changes in cerebral vasoconstriction associated with hyperventilation-induced hypocapnia. The present study investigated the role of cardiovascular and respiratory activity in self-reported pre-syncopal vasovagal reactions to a surgery video in a sample of 49 healthy women. Participants who indicated more previous real-life episodes of dizziness reported experiencing significantly more symptoms in the laboratory consistent with a vasovagal response. They also showed lower total peripheral resistance and higher pre-ejection period in general, suggesting lower sympathetic nervous system activity. Significant decreases in end-tidal carbon dioxide (PETCO2) occurred during the surgery video among susceptible participants, without significant increases in respiration rate. Further, participants who experienced reductions from the neutral video in PETCO2, systolic blood pressure, or both, reported vasovagal symptoms during the surgery video. The results suggest that patterns of respiration associated with decreases in PETCO2 may contribute to vasovagal symptoms reported in non-clinical groups as well as those with blood-injection-injury phobia and are associated with susceptibility to dizziness.

The qualitative detection of decreases in cardiac output

BackgroundCardiac output is a major factor in the maintenance of physiological homeostasis and is difficult to measure with accuracy. This study describes an evidence-based technique, based on physiological changes, which may indicate small changes in cardiac output that cannot be measured by current techniques. MethodSynchronous changes in blood pressure, heart rate, pulse amplitude and end-tidal carbon dioxide are analysed using runs analysis and a normalisation technique. An evidence-based algorithm was used to detect possible changes in cardiac output and data extracts from 31 consenting patients are presented as examples. ResultsThe decrease in end-tidal carbon dioxide, during steady state ventilation, was greater in those events notified as hypovolaemia associated with a fall in cardiac output than those events notified as hypovolaemia alone. The difference in end-tidal carbon dioxide between the two groups was −0.25kPa (CI −0.42 to −0.09) p<0.003. DiscussionRuns analysis can detect trends in EtCO2 that during steady state ventilation may indicate a decrease in cardiac output. It is a safe technique; no additional hardware is required and the generated alerts only notify the clinician of the possibility of an adverse change. Determination of the rate of clinically significant false positives and negatives requires further work.

Effects of Subanesthetic Dose of Nitrous Oxide on Cerebral Blood Flow and Metabolism

Nitrous oxide, in a concentration of 50% or more, is a known cerebral vasodilator. This study investigated whether a lower dose (30%) of nitrous oxide would also increase cerebral blood flow. In addition, the authors wished to study whether the increase in cerebral blood flow was accompanied by an increase in cerebral metabolism. Multimodal Magnetic Resonance Imaging at 3T was performed, and data were obtained in 17 healthy volunteers during three inhalation conditions: medical air, oxygen-enriched medical air (40% oxygen), and 30% nitrous oxide with oxygen-enriched medical air (40% oxygen). Arterial spin labeling was used to derive the primary tissue specific hemodynamic outcomes: cerebral blood flow, arterial blood volume and arterial transit times. Magnetic Resonance Susceptometry and proton Magnetic Resonance Spectroscopy were used for secondary metabolic outcomes: venous oxygenation, oxygen extraction fraction, cerebral metabolic oxygen rate and prefrontal metabolites. Nitrous oxide in 40% oxygen, but not 40% oxygen alone, significantly increased gray matter cerebral blood flow (22%; P < 0.05) and arterial blood volume (41%; P < 0.05). Venous oxygenation increased in both oxygen and nitrous oxide conditions. Compared with medical air inhalation, nitrous oxide condition caused a significantly larger decrease in oxygen extraction fraction than 40% oxygen alone (mean [SD] 11.3 [5.6]% vs. 8.3 [5.9]% P < 0.05), while global cerebral metabolic rate and prefrontal metabolites remained unchanged. This study demonstrates that 30% nitrous oxide in oxygen-enriched air (40% oxygen) significantly increases cerebral perfusion, and reduces oxygen extraction fraction, reflecting a strong arterial vasodilatory effect without associated increases in metabolism.

Successful resuscitation after suspected carbon dioxide embolism during laparoscopic ureteric reconstructive surgery

Carbon dioxide (CO2) embolism is a rare but potentially fatal complication of laparoscopic surgery. We report a case of presumed CO2 embolism in a 35-year-old female during laparoscopic ureteric reconstructive surgery. After 2 h of operating time, a sudden decrease in end-tidal carbon dioxide and deterioration of hemodynamic status followed by cardiac arrest with pulseless electrical activity suggested gas embolism. Immediate cardiopulmonary resuscitation and inotropic support resulted in successful outcome. Thus, early recognition of the complication and prompt treatment can avoid catastrophy.

Sudden decrease in end-tidal carbon-dioxide in a neonate undergoing surgery for type B interrupted aortic arch

Interruption of the aortic arch is a rare anomaly affecting 1% of children with congenital heart disease. The systemic circulation is ductal dependent and is determined principally by the ratio of the resistances in the systemic and the pulmonary vascular bed. Any increase in the pulmonary vascular resistance may increase the dead space ventilation due to acute pulmonary hypoperfusion. We report a case where sudden decreases in the end-tidal carbon-dioxide due to pulmonary hypoperfusion mimicked accidental endotracheal tube extubation in an infant undergoing repair of interrupted aortic arch.

Gas embolus and cardiac arrest during laparoscopic pyloromyotomy in an infant

High volume tubing is used to deliver carbon dioxide during laparoscopic procedures. Failure to prime the tubing with carbon dioxide prior to abdominal insufflation may result in the delivery of nitrogen-containing air to the abdominal cavity. We report a case in which initial insufflation of laparoscopic gas resulted in immediate cardiovascular collapse requiring prolonged resuscitation. Persistent intracranial emboli following the arrest may have resulted from nitrogen contamination of the delivered gas. A 12-day-old female underwent laparoscopy for pyloric stenosis. During initial insufflation of the abdomen, the patient had an abrupt decrease in end-tidal carbon dioxide (CO(2ET)) associated with bradycardia and pulseless electrical activity. Three hours after successful resuscitation and open pyloromyotomy, computerized tomography documented intra-arterial gas within the cerebral and hepatic circulations that resolved following hyperbaric oxygen therapy. Magnetic resonance imaging five days later revealed watershed infarcts in the right frontal and parietal regions. Nitrogen, an insoluble gas not easily eliminated from the body, was likely the gas present within the patient's circulation several hours after the event. It was unlikely carbon dioxide, which is a highly soluble gas that binds to hemoglobin and is rapidly buffered by the carbonic anhydrase system and excreted by the lung. Room air contamination of high volume insufflation tubing allows nitrogen to enter body cavities during endoscopic procedures. Persistence of emboli following endoscopic procedures suggests that the entrained gas is insoluble. Room air contamination increases the potential for catastrophic events during laparoscopy and other endoscopic procedures.

Massive pulmonary gas embolism in a neonate with ileal atresia and meconium peritonitis

We presented the case of a neonate with portal venous gas and pulmonary gas embolism. The patient presented with severe respiratory distress and abdominal distension 12 hours after birth. An ultrasound revealed intravascular microbubbles moving into a pulmonary artery that were traveling from the portal venous system through a ductus venosus. Additional clinical observations were hypotension and a sudden decrease in end-tidal carbon dioxide with a markedly discrepant high P co 2, indicating a massive pulmonary gas embolism. Operative findings revealed congenital ileal atresia and meconium peritonitis with abscess. Gas-forming Escherichia coli was recovered from the abscess contents. The patient had respiratory distress, shock, disseminated intravascular coagulation, and intractable diarrhea but eventually recovered and was discharged on the 131st postoperative day.

Inability to detect unintentional endobronchial intubation by conventional signs and its detection by the radiologist during fluoroscopy for cerebral aneurysm coiling

It is routine practice to auscultate the chest for equal bilateral breath sounds after tracheal intubation to verify that the tracheal tube tip is properly positioned. Signs of bronchial intubation also include desaturation, an increase or decrease in end-tidal carbon dioxide, and an increase in peak airway pressures. We report a case in which, during the course of endovascular coiling of a cerebral aneurysm during general anesthesia, desaturation occurred despite seemingly equal air entry on chest auscultation. The clinical picture was confused further by the presence of normal airway pressures and capnography. Incidental detection of bronchial intubation by the radiologist while performing fluoroscopy prevented any adverse sequelae to the patient and also presented an unusual method of diagnosis.

Air Embolism during Intraoperative Endoscopic Localization and Surgical Resection for Blue Rubber Bleb Nevus Syndrome

Air Embolism during Intraoperative Endoscopic Localization and Surgical Resection for Blue Rubber Bleb Nevus Syndrome

Venous air embolism during radical perineal prostatectomy

An abrupt decrease in end-tidal carbon dioxide (CO 2) occurred in an anesthetized male who was placed in the head down position during radical perineal prostatectomy. The end-tidal CO 2 was restored after insertion of a wet pack into the operative site, which strongly indicated venous air embolism as the cause. Predisposing factors, detection, and treatment of venous air embolism in this setting are discussed.

The effect of nasal oxygen flow and catheter position on the accuracy of end‐tidal carbon dioxide measurements by a pharyngeal catheter in unintubated, spontaneously breathing subjects

Reliable recordings of carbon dioxide concentrations during spontaneous respiration can be obtained from a catheter positioned in the hypopharynx. The present study investigated the possible influence on end-tidal carbon dioxide measurement of nasal oxygen administration, position of the sampling catheter and mouth breathing. The study demonstrated that not only can reliable capnographic tracings be obtained from a thin catheter placed in the unintubated airway, but the subject may also receive up to 6 l.min-1 of oxygen via the nasal route without interference with the accuracy of the measurements. Furthermore, the exact position of the sampling catheter tip in the airway is not critical, which means that it may be placed where it causes the patient least discomfort. Finally, mouth breathing caused a mean decrease in end-tidal carbon dioxide of 0.25 kPa compared to nose breathing.