Key points are not available for this paper at this time.
During anesthesia, capnography is a vital monitoring modality that allows for continuous assessment of a patient's respiratory and metabolic condition. Clinicians can be made aware of possible problems such as respiratory compromise, equipment malfunction, or obstruction of the airway by abnormalities in capnography readings.1 Here, we report a case of abnormality found on capnography during the induction stage of a laparoscopic hernia repair procedure. A 45-year-old male patient, classified as American Society of Anesthesiologists Physical Status I, was slated for an elective laparoscopic hernia repair procedure under general anesthesia. The preoperative assessment revealed a clean bill of health with no significant medical history or underlying health conditions. As per protocol, standard monitoring procedures were initiated upon the patient's arrival in the operating room. This included electrocardiography to monitor heart activity, noninvasive blood pressure measurement, pulse oximetry to gauge oxygen saturation levels, and capnography to assess carbon dioxide levels in exhaled breath, thus ensuring comprehensive vigilance during the anesthesia process. Following adequate preoxygenation to optimize oxygen reserves, the anesthesia induction phase commenced. Intravenous administration of propofol, a commonly used anesthetic agent, was employed to induce unconsciousness, while atracurium, a neuromuscular blocking agent, facilitated muscle relaxation for intubation purposes. Using a video laryngoscope, a medical device aiding in visualizing the airway, endotracheal intubation was performed. An appropriately sized 7-size cuffed endotracheal tube was meticulously positioned at the level of the lips and advanced approximately 20 cm into the trachea. Verification of correct tube placement was confirmed by observing equal chest rise and bilateral breath sounds upon auscultation. Despite these seemingly adequate measures, the capnography waveform displayed an abnormal pattern indicative of single lung ventilation Figure 1a. This unexpected observation prompted an immediate and thorough investigation to identify potential causes, including bronchospasm, inadvertent endobronchial intubation, or equipment malfunction. To definitively assess the position of the endotracheal tube, a comprehensive examination utilizing bilateral five-point chest auscultation was performed. In addition, plans were made for fiber-optic bronchoscopy, a highly precise diagnostic tool, to visually confirm tube placement within the trachea.Figure 1: Capnography troubleshooting image. (a) Multipara monitor showing the capnograph as one-lung ventilation (OLV) pattern. (b) water trap of side stream capnography with the red arrow showing the site where the connection was loose. (c) Multipara monitor showing the capnograph changed to normal as the water trap is fixed correctly and red arrow showing the transition point from OLV capnograph to normal capnographHowever, before proceeding with further invasive measures, a meticulous inspection of the anesthesia circuit revealed a critical issue. It was discovered that a water trap component within the side stream capnography monitor was loosely fitted Figure 1b, causing an interruption in the flow of gases. This disruption led to erroneous readings on the capnography monitor, falsely indicating single lung ventilation. Rectifying this equipment malfunction swiftly resolved the discrepancy, obviating the need for additional interventions such as fiber-optic bronchoscopy. Fast equipment correction was achieved by tightening the water trap connection. Subsequent capnography monitoring displayed normal waveform patterns consistent with bilateral lung ventilation, as shown in Figure 1c. The surgery proceeded uneventfully with stable intraoperative hemodynamics and ventilation parameters. At the end of the procedure, the patient was successfully extubated in the operating room without complications. Upon postoperative evaluation, there were no untoward incidents, and the patient was shifted to the ward on the same day. Capnography is an invaluable tool for assessing the adequacy of ventilation and detecting respiratory abnormalities during anesthesia.2 The presented case emphasizes the significance of recognizing and addressing capnography anomalies, particularly those arising from equipment issues such as loose water traps. An unexpected deviation in capnography waveform patterns can lead to erroneous clinical interpretations, potentially compromising patient safety during anesthesia.3,4 When analyzing capnography tracings, clinicians must be astute in differentiating between physiological, anatomical, and equipment-related factors. In this instance, the irregular waveform indicative of single lung ventilation initially led to concerns regarding endotracheal tube misplacement. However, thorough assessment and confirmation through auscultation ruled out anatomical issues, directing attention toward equipment malfunction. A loosely fitted water trap in the side stream EtCO2 monitor disrupted the gas flow, manifesting in the aberrant waveform pattern. Without prompt identification and rectification of this equipment issue, the anomaly persisted despite correct endotracheal tube positioning. This highlights the necessity of meticulous equipment checks and regular maintenance protocols to prevent such disruptions that could compromise patient safety. In considering differential diagnoses for capnography anomalies associated with loose water traps, it is crucial to acknowledge the spectrum of potential waveform variations.5,6 These could include but are not limited to: Single lung ventilation pattern: As observed in the presented case, a waveform resembling single lung ventilation may emerge due to interrupted gas flow caused by a loose water trap Partial airway obstruction: A partial obstruction in the airway can lead to fluctuations or distortions in the capnography waveform, indicating compromised ventilation Artifact or technical error: Equipment-related issues beyond loose water traps, such as sensor malfunction or disconnection, can result in distorted or absent capnography waveforms Respiratory distress or disease: Underlying respiratory conditions or acute respiratory distress can manifest in distinct capnography patterns, necessitating careful evaluation, and clinical correlation Hypoventilation or hyperventilation: Altered respiratory rates or depths can influence the shape and amplitude of capnography waveforms, warranting consideration in the differential diagnosis Cardiopulmonary resuscitation (CPR) artifacts: During CPR maneuvers, chest compressions can generate artifacts on the capnography tracing, mimicking abnormal respiratory patterns Mechanical ventilation settings: Improper ventilator settings or mechanical issues can lead to irregularities in capnography waveforms, necessitating adjustment, or troubleshooting. In conclusion, the timely identification and resolution of capnography anomalies are crucial for maintaining patient safety during anesthesia. This case underscores the necessity of thorough equipment checks, vigilant monitoring, effective communication, and continuous education to optimize patient outcomes in perioperative care. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients/family members have given their consent for their images and other clinical information to be reported in the journal. The patients/family members understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Dhanger et al. (Fri,) studied this question.