Inadvertent severe hypercapnia during general anesthesia: drop-in oxygen saturation or electrocardiography changes; which one warns us earlier?

Background During general anesthesia especially when the nurse or anesthesiologist forgets to change manual to controlled mode after successful endotracheal intubation, capnography shows End-tidal Co2 above 20 mmHg after checking the place of the tracheal tube and will remain on the screen permanently. In this scenario, the patient receives a high concentration of oxygen, and Spo2 (oxygen saturation) does not drop for a long time which is too late to intervene. It has been all-time questionable which one of the cardiac dysrhythmias or Spo2 dropping occurs earlier. Results Medical records of seven deceased patients reviewed. All of them had electrocardiogram changes including premature ventricular contraction or bradycardia as a first warning sign. Oxygen saturation remains above 95% even with cardiac dysrhythmia. Conclusions Bradycardia and premature ventricular contraction were the first warning findings for severe hypercapnia during general anesthesia and occurred earlier than dropping oxygen saturation. Furthermore, the normal capnography waveform is more reliable than the End-tidal Co2 number for monitoring.

Cardiac Arrest due to Carbon Dioxide Embolism During Laparoscopic Gynecologic Surgery of a Patient with Previous Abdominal Surgery: A Case Report

Catastrophic carbon dioxide (CO2) embolism is a rare, but potentially life-threatening, the complication of laparoscopic gynecologic surgery. We report the case of a healthy 53-year-old woman who developed CO2 embolism and cardiac arrest during laparoscopic surgery. She had a history of two cesarean sections and had extensive peritoneal adhesions. After placement of the trocar and insufflation of CO2, end-tidal CO2 dropped from 35 to 15 mm Hg, and the patient had a cardiovascular collapse. In this patient, CO2 embolism was diagnosed on the basis of a sudden decrease in end-tidal CO2, hypotension, and hypoxemia. The patient was managed quickly and aggressively. The patient recovered completely following the treatment for CO2 embolism, with no cardiopulmonary or neurological sequelae. There is an increased risk of catastrophic CO2 embolism during laparoscopic gynecologic surgery in patients with previous abdominal surgery. Therefore, the surgeon and anesthesiologist should remain vigilant to promote early detection of CO2 embolism.

A PHASE IIA OPEN LABEL STUDY TO EVALUATE THE SAFETY, TOLERABILITY AND EFFICACY OF S-1226 ADMINISTERED BY NEBULIZATION IN SUBJECTS WITH CYSTIC FIBROSIS LUNG DISEASE

Rationale: There are approximately 35,000 people with Cystic Fibrosis (CF) in North America. This condition is characterized by impaired airway clearance resulting in chronic infection and bronchiectasis. Current airway clearance treatments include nebulized hypertonic saline and Recombinant Human DNase, which may be limited by bronchospasm and cost, respectively. S-1226, a novel biophysical therapeutic agent combines carbon dioxide (CO2) enriched air (a bronchodilator) with nebulized perflubron (PFOB), (a synthetic surfactant). They act synergistically to open airways, enhance mucus clearance, and increase blood oxygenation. We report preliminary results from a Phase II clinical trial. Methods: An open label, single-center, Phase IIa study of subjects (≥14 years) with mild-moderate (FEV1 40-80%) CF lung disease treated with multiple ascending doses of S-1226 (week one), followed by the highest tolerated dose for 5 consecutive days (week two). Each dose of S-1226 comprised three successive treatments of 3mL of perflubron nebulized (Circulaire II) for two-minutes with CO2 concentrations ranging from 4 to 12%. The oxygen concentration was maintained at ambient levels. Treatments were administered twice daily. Efficacy measurements included spirometry, lung clearance index (LCI), lung volumes, blood oxygenation (SPO2), sputum weight and the respiratory domain of quality of life (QOL) questionnaire (CFQ-R). Safety included adverse event (AE) and tolerance monitoring, vital signs, and assessment of end-tidal CO2. Results: We report preliminary data on safety and efficacy for six CF subjects. All subjects tolerated all doses of S-1226. There were 5 reported AEs in 3 subjects. All were mild and resolved spontaneously. End-tidal CO2 immediately after treatment was comparable to baseline. SpO2 (baseline 91-95%) rapidly improved in all subjects with treatment. Five of six subjects had improvements in their LCI. Three subjects that were compliant in collecting mucus showed increases of 14%, 29% and 64% over baseline. Percent predicted FEV1 response was variable, decreasing initially with return to baseline values at two weeks. Four of the six subjects reported improvements in CFQ-R scores, three of which showed a clinically important difference (> 4 points). An important observation was that S-1226 controlled irritant (but not productive) cough in all five subjects and at all concentrations of S-1226. Conclusions: All doses of S-1226 were safe and well tolerated. Treatments with up to 12% extrinsic CO2 over short periods of time did not result in an elevation of end-tidal CO2. The preliminary efficacy results, including overall improved oxygen saturation, CFQ-R scores, increased expectorated mucus and LCI values provide evidence for potential beneficial effects of S-1226 for CF lung disease but require larger trials and longer-term treatments to fully assess efficacy in CF.

Abstract 13737: Enhanced Prehospital End-Tidal CO2 Monitor Data Analysis for Intubated Severe Traumatic Brain Injury: Striking Findings From the EPIC Study

Background: Studies show that EMS patients are often inadvertently hyperventilated (HV), resulting in hypocapnia. In TBI, HV markedly increases mortality. We evaluated continuous prehospital ETCO2 data in intubated TBI patients. Methods: Analysis of monitor data files (Philips MRx™) from a sample of intubated TBI cases in the EPIC Study (NIH-R01NS071049). Results: Among hundreds of cases, graphical display of continuous ETCO2 from 3 subjects dramatically exemplified commonly-occurring inadvertent HV. Fig 1 shows unrecognized HV lasting nearly 15 min. Fig 2 reveals nearly 14 min of increasing ventilatory rate and progressively worsening hypocapnia. Fig 3 shows nearly 4 min of HV that ends abruptly with clear, sudden recognition and slowing of ventilatory rate that leads to restoration of normal ETCO2 in only a few breaths. The corresponding EMS patient care records (PCR) failed to document the presence, severity, and duration of HV. Conclusions: In a study emphasizing prevention of HV, subsequent evaluation of continuous ETCO2 data revealed many cases of unintentionally rapid manual ventilation and severe hypocapnia, often occurring for long periods. These findings, even in the face of explicit guideline-based training, demonstrate a clear need for routine access to continuous monitor data among intubated patients for quality improvement and in clinical studies. Review of PCRs does not reliably identify mismanagement of ventilation. Furthermore, these findings make it likely that real-time audiovisual feedback technology would improve ventilatory management by alerting providers to unidentified HV that results from the frequent distractions occurring during EMS care.

Transcutaneous and End-Tidal CO2 Measurements in Hypoxia and Hyperoxia

BACKGROUND: Transcutaneous measurement of carbon dioxide (CO2) has been proposed for physiological monitoring of tactical jet aircrew because in some clinical settings it mirrors arterial CO2 partial pressure (Paco2). End-tidal monitoring in laboratory settings is known to give high-fidelity estimates of Paco2.METHODS: The correspondence between end-tidal (PETco2) and transcutaneous Pco2 (tcPco2) was examined in healthy volunteers under laboratory conditions of hyperoxia and hypoxia. Rest and exercise, skin heating and cooling, hyperventilation, and induced CO2 retention were employed.RESULTS: Neither measure followed all known changes in Paco2 and tcPco2 changed when the skin temperature near the probe changed. Bland-Altman analysis showed significant nonzero slopes under most conditions. Regression analysis indicated that oxygen partial pressure (Po2) in tissue measured as transcutaneous Po2 (tcPo2) is an important explanatory variable for tcPco2 in addition to PETco2, and that local skin temperature also has an effect. Additionally, absorption atelectasis from breathing 100% O2 may cause PETco2 to deviate from Paco2.DISCUSSION: Even as a trend indicator for Paco2, tcPco2 is not useful under conditions that resemble those in the highly dynamic tactical jet aircraft environment. PETco2 is also not a good indicator of CO2 status in pilots who breathe nearly 100% O2.Shykoff BE, Lee LR, Gallo M, Griswold CA. Transcutaneous and end-tidal CO2 measurements in hypoxia and hyperoxia. Aerosp Med Hum Perform. 2021; 92(11):864-872.

REBOA-Assisted Resuscitation in Non-Traumatic Cardiac Arrest due to Massive Pulmonary Embolism: A Case Report with Physiological and Practical Reflections

We present the case of a 36-year old woman who suffered a non-traumatic out-of-hospital cardiac arrest. The resuscitation attempt included the use of a resuscitative endovascular balloon occlusion of the aorta (REBOA) catheter which resulted in a return of spontaneous circulation and distinct improvements in arterial blood pressure, end-tidal CO2 and cerebral oximetry values. This suggests that the use of REBOA may improve the rate of both survival and favorable neurologic outcome and warrants further study.

Amiodarone and amplitude spectral area of ventricular fibrillation in patients with out-of-hospital cardiac arrest

Background Ventricular fibrillation is the most common cause of out-of-hospital cardiac arrest (OHCA) and the use of antiarrhythmic drug therapy is usually recommended in addition to defibrillation. The role of the amplitude spectral area (AMSA) of ventricular fibrillation as a predictor of defibrillation efficacy has been established, while the existing data in favour of the use of amiodarone has been assessed with poor evidence and controversy. Purpose The aim of our study is to evaluate whether the administration of amiodarone during resuscitation could affect AMSA values. Materials All the OHCAs with a shockable presenting rhythm and attempted resuscitation which occurred from January 2015 to June 2019 in the province of Pavia were considered. Both the end-tidal CO2 (ETCO2) and AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators (Corpuls, Kaufering, Germany) used in the territory and by considering a pre-shock interval of 2 seconds. Results Among a total of 3413 OHCAs, resuscitation was attempted in 2195 cases (64%), 377 (17%) had a shockable presenting rhythm and in 112 cases (3.4%) it was possible to obtain the values of ETCO2 and AMSA for a total of 391 shocks. Among these, 301 shocks (77%) were delivered to patients who received amiodarone during resuscitation. The success rate of each single shock was similar in the two groups but with an unfavorable trend for amiodarone (amiodarone 43.5% vs no amiodarone 54.4%, p=0.07). AMSA was significantly lower in patients treated with amiodarone (7.9 mV·Hz, IQR 5.4–12.2 vs 10.6 mV·Hz, IQR 7.1–14.1; p<0.001). According to a multivariate analysis, the administration of amiodarone and the time to shock were independent predictors of AMSA values. Lastly, on a sample of 124 shocks, homogeneous for age, sex, ETCO2, outcome of resuscitation and randomly matched, the AMSA of patients who received amiodarone was significantly lower (7.2 mV·Hz, IQR 7.2–11.7 vs 9.7 mV·Hz, IQR 6.7–12.5; p=0.02). Conclusions Our results indicate that amiodarone administration is associated with lower values of AMSA. Since higher AMSA values are known to be associated with a higher probability of shock rate success, this could help to better clarify the controversial role of amiodarone administration in patients with OHCA. FUNDunding Acknowledgement Type of funding sources: None.

Volumetric Capnometry, more than end-tidal carbon dioxide

Monitoring the exhaled caron dioxide pressure, known as end-tidal CO2 (ETCO2) has become the standard of care during anesthesia, intensive care units, and during cardiac arrest resuscitation. However, volumetric capnometry provides much more useful information other than the ETCO2.