Low End-tidal Carbon Dioxide Research Articles

Pulmonary Embolism as a Consequence of Applying Sequential Compression Device on Legs in a Patient Asymptomatic of Deep Vein Thrombosis

INTRAOPERATIVE pulmonary embolism (PE) is an uncommon complication of emergency intraabdominal surgery. Best practice recommendations for longer surgical cases include the fitting of antithrombotic leg devices such as stockings and pneumatic compression devices. 1,2 Although these devices certainly prevent thrombosis in deep vein thrombosis (DVT)-prone surgical patients, 1,2 we were unable to find reports of any significant complications caused by them (besides minor skin bruising, sores, etc.), namely, dislodgment of a pre-existing thrombus, causing a life-threatening PE. Although PE has been observed after tourniquet deflation in orthopedic surgery cases, 3 we report a case of PE possibly related to pneumatic sequential compression device.

Psychological and physiological parameters of masticatory muscle pain

The objective of this research was to identify the psychological and physiological variables that differentiate persons reporting masticatory muscle pain (MMP) from normal controls (NC). This study examined the characteristics of 35 MMP patients in comparison to 35 age-, sex-, and weight-matched NCs. All subjects completed a series of standardized questionnaires prior to undergoing a laboratory evaluation consisting of a psychosocial stressor and pressure pain stimulation at multiple body sites. During the evaluation, subjects' emotional and physiological responses (heart rate, blood pressure, respiration, skin temperature, and muscle activity) were monitored. Results indicated that persons with MMP reported greater fatigue, disturbed sleep, depression, anxiety, menstrual symptoms, and less self-deception ( P's<0.05) than matched controls. At rest, MMPs had lower end tidal carbon dioxide levels ( P<0.04) and lower diastolic blood pressures than the NCs ( P<0.02). During laboratory challenge, both groups responded to the standard stressor with significant physiological activity and emotional responding consistent with an acute stress response ( P<0.01), but there were no differences between the MMPs and NCs. Muscle pain patients reported lower pressure pain thresholds than did NCs at the right/left masseter and right temporalis sites ( P's<0.05); there were no differences in pressure pain thresholds between MMPs and NCs for the left temporalis ( P<0.07) and right/left middle finger sites ( P's>0.93). These results are discussed in terms of the psychological and physiological processes that may account for the development of muscle pain in the masticatory system.

Complete recovery after near-fatal venous air embolism during cesarean section

During replacement to the abdomen of the exteriorized uterus at cesarean section under epidural block, a previously healthy woman developed cardiorespiratory arrest. Tracheal intubation revealed low endtidal carbon dioxide concentration suggesting embolization. Resuscitative efforts were successful. Uterine exteriorization — as well as the Trendelenburg position - significantly increase the risk of air embolization so that routine use of appropriate monitors is indicated to facilitate early diagnosis.

Cardiorespiratory exercise performance after Senning operation for transposition of the great arteries.

To assess the cardiorespiratory response to graded exercise in patients after the Senning operation for transposition of the great arteries. Cross sectional study. Exercise performance was assessed by determination of the ventilatory anaerobic threshold. This was defined as the exercise intensity at which the ventilatory equivalent for oxygen (VE/VO2) started to increase systematically without a concomitant increase in the ventilatory equivalent for carbon dioxide (VE/VCO2). Outpatient department. Sequential sample of 20 patients studied 5-10 years (mean 7.3 years) after the Senning operation. Age at exercise testing varied from 5 to 11 (mean 7.8) years. The ventilatory threshold in the patients was significantly lower than normal (p < 0.005) and averaged 79.3% (SD 13%) and 80% (12%) of the predicted normal value for age and weight, respectively. Also, the ventilatory threshold was surpassed sooner (mean 3.2 (range 2-5) minutes) in the patients than in normal controls (3.9 (2.6-4.6) minutes). The lower ventilatory threshold was associated with a subnormal oxygen uptake (ml/min/kg) during submaximal exercise, a higher than normal ventilatory equivalent for oxygen ratio, and a lower end tidal carbon dioxide tension in the patients compared with normal controls. In half of the patients heart rate was lower during graded exercise. This relative bradycardia was not associated with a normal ventilatory threshold, as often seen in fit young people. No major disturbances in rhythm were observed during exercise. Exercise performance, assessed by respiratory gas exchange, was slightly but significantly lower than normal in patients after the Senning operation. A subnormal ventilatory threshold, associated with a higher than normal ventilatory response during submaximal exercise, supports the hypothesis that oxygen delivery to tissues is slightly impaired in these patients.

Hemodynamic monitoring during CPR

Real-time hemodynamic monitoring provides useful information that can be used to assess and optimize mechanical and pharmacological interventions during CPR. The standard algorithms should always be the initial approach to resuscitation, because they offer a rapid, logical, coordinated series of treatments with proven success. Pressure and flow measurements during conventional, closed-chest CPR in humans indicate that the technique typically produces a hemodynamic state resembling profound cardiogenic shock, with a low systemic arterial pressure, markedly reduced cardiac output, and high intravascular filling pressures. End-tidal carbon dioxide monitoring provides useful, noninvasive information during clinical resuscitation. A low end-tidal carbon dioxide value during resuscitation should alert the rescuers that something is wrong with ventilation, perfusion, and/or carbon dioxide production and should prompt a search for correctable causes. If one or more hemodynamic parameters are being monitored at the time the patient develops cardiac arrest (eg, an intensive care unit patient who has an arterial line and a pulmonary artery catheter in place), it is appropriate for the resuscitation team to pay attention to the data that are generated during the resuscitation, particularly if the initial algorithm approach is not successful. For patients who are not being monitored at the time of their arrest, end-tidal carbon dioxide measurements provide noninvasive, semiquantitative information that can help the team detect and troubleshoot problems during resuscitation. Further research and better, more affordable technologies are needed to provide in- and out-of-hospital resuscitation teams feedback on the hemodynamic effectiveness of their resuscitative efforts.

Sensitivity of a disposable end-tidal carbon dioxide detector

A small disposable carbon dioxide detector that can be used to provide evidence of correct endotracheal tube placement is now commercially available (FEF). The device contains an indicator that changes color when exposed to carbon dioxide. This study measured the lowest concentration of carbon dioxide causing a perceivable color change in the device. Ten volunteers were blinded to the concentrations of carbon dioxide in an airway circuit/lung model, and the minimal concentration of carbon dioxide that caused a perceivable color change was recorded. The mean minimum concentration required for detection of a color change was 0.54% (4.1 mm Hg) and ranged from 0.25 to 0.60% (1.9 to 4.6 mm Hg). We conclude that this device should produce a detectable color change even in patients with low end-tidal carbon dioxide, as might be observed during cardiopulmonary resuscitation.

The Bain, ADE, and Enclosed Magill breathing systems A comparative study during controlled ventilation

The Enclosed Magill, Humphrey ADE and the Bain breathing systems are all used for controlled ventilation of the lungs. This study compares the three systems in vitro with a lung model and in clinical practice. No difference was observed, with ventilatory variables commonly used in clinical practice, between the Bain and the ADE, while significantly lower end-tidal carbon dioxide values were observed with the Enclosed Magill (about 7%). Lower fresh gas flows can be used under these circumstances to maintain normocapnia with the Enclosed Magill than either the Bain or the Humphrey ADE.

Cardiopulmonary response to dynamic exercise after heart and combined heart-lung transplantation.

The exercise capacity and cardiopulmonary response to progressive dynamic exercise of eight healthy recipients of heart-lung transplants were compared with those of matched recipients of orthotopic cardiac transplants and normal controls. In both transplant groups the maximum workloads were lower than that in the normal group. The transplant recipients had higher pre-exercise heart rates and lower maximum heart rates than the normal controls. Ventilation during submaximal exercise was similar in the heart transplant group and the controls. The heart-lung group had an increased ventilatory response associated with lower end tidal carbon dioxide concentrations. Exercise capacity after combined heart-lung transplantation is similar to that after cardiac transplantation. Transplant recipients have an abnormal heart rate response during exercise related to cardiac denervation. The altered ventilatory response in heart-lung recipients may be the result of pulmonary denervation.