End-tidal CO2 Gradient Research Articles

Monitoring persistent pulmonary hypertension of the newborn using the arterial to end tidal carbon dioxide gradient

Persistent pulmonary hypertension of the newborn (PPHN) can be monitored theoretically by the difference of the partial pressure of arterial (PaCO2) to end-tidal CO2 (EtCO2). We aimed to test the hypothesis that the PaCO2–EtCO2 gradient in infants with PPHN would be higher compared to infants without PPHN. Prospective, observational study of term-born ventilated infants with echocardiographically-confirmed PPHN with right-to-left shunting and term-born control infants without respiratory disease. The PaCO2–EtCO2 gradient was calculated as the difference between the PaCO2 measured from indwelling arterial sample lines and EtCO2 measured by continuous Microstream sidestream capnography. Twenty infants (9 with PPHN and 11 controls) were studied with a median (IQR) gestational age of 39.5 (38.7–40.4) weeks, a birthweight of 3.56 (3.15–3.93) kg and a birthweight z-score of 0.03 (− 0.91 to 1.08). The PaCO2–EtCO2 gradient was larger in the infants with PPHN compared to those without PPHN after adjusting for differences in the mean airway pressure and fraction of inspired oxygen (adjusted p = 0.037). In the infants with PPHN the median PaCO2–EtCO2 gradient decreased from 10.7 mmHg during the acute illness to 3.3 mmHg pre-extubation. The median difference in the gradient was significantly higher in infants with PPHN (6.2 mmHg) compared to infants without PPHN (-3.2 mmHg, p = 0.022). The PaCO2–EtCO2 gradient was higher in infants with PPHN compared to term born infants without PPHN and decreased over the first week of life in infants with PPHN. The gradient might be utilised to monitor the evolution and resolution of PPHN.

Frequency and characterization of CTEPH and CTEPD according to the mPAP threshold > 20 mm Hg: Retrospective analysis from data of a prospective PE aftercare program

BackgroundThe influence of the new pulmonary hypertension (PH) definition on the incidence of chronic thromboembolic PH (CTEPH) is unclear. The incidence of chronic thromboembolic pulmonary disease without PH (CTEPD) is unknown. ObjectivesTo determine the frequency of CTEPH and CTEPD using the new mPAP cut-off >20 mmHg for PH in patients who have suffered an incidence of pulmonary embolism (PE) and were recruited into an aftercare program. MethodsIn a prospective two-year observational study based on telephone calls, echocardiography and cardiopulmonary exercise tests, patients with findings suspicious for PH received an invasive work-up. Data from right heart catheterization were used to identify patients with or without CTEPH/CTEPD. ResultsTwo years after acute PE (n = 400) we found an incidence of 5.25% for CTEPH (n = 21) and 5.75% for CTEPD (n = 23) according to the new mPAP threshold >20 mmHg. Five of 21 patients with CTEPH and 13 of 23 patients with CTEPD showed no signs of PH in echocardiography. CTEPH and CTEPD subjects showed a reduced VO₂ peak and work rate in cardiopulmonary exercise testing (CPET). The capillary end-tidal CO2 gradient was comparably elevated in CTEPH and CTEPD, but it was normal in the Non-CTEPD-Non-PH group. According to the PH definition provided by the former guidelines, only 17 (4.25%) patients have been diagnosed with CTEPH and 27 individuals (6.75%) were classified having CTEPD. ConclusionsUsing mPAP >20 mmHg for diagnosis of CTEPH leads to an increase of 23.5% of CTEPH diagnosis. CPET may help to detect CTEPD and CTEPH.

Lung mechanics during video-assisted abdominal surgery in Trendelenburg position: a cross-sectional propensity-matched comparison between classic laparoscopy and robotic-assisted surgery

BackgroundVideo-assisted surgery has become an increasingly used surgical technique in patients undergoing major thoracic and abdominal surgery and is associated with significant perioperative respiratory and cardiovascular changes. The aim of this study was to investigate the effect of intraoperative pneumoperitoneum during video-assisted surgery on respiratory physiology in patients undergoing robotic-assisted surgery compared to patients undergoing classic laparoscopy in Trendelenburg position.MethodsTwenty-five patients undergoing robotic-assisted surgery (RAS) were compared with twenty patients undergoing classic laparoscopy (LAS). Intraoperative ventilatory parameters (lung compliance and plateau airway pressure) were recorded at five specific timepoints: after induction of anesthesia, after carbon dioxide (CO2) insufflation, one-hour, and two-hours into surgery and at the end of surgery. At the same time, arterial and end-tidal CO2 values were noted and arterial to end-tidal CO2 gradient was calculated.ResultsWe observed a statistically significant difference in plateau pressure between RAS and LAS at one-hour (26.2 ± 4.5 cmH2O vs. 20.2 ± 3.5 cmH2O, p = 0.05) and two-hour intervals (25.2 ± 5.7 cmH2O vs. 17.9 ± 3.1 cmH2O, p = 0.01) during surgery and at the end of surgery (19.9 ± 5.0 cmH2O vs. 17.0 ± 2.7 cmH2O, p = 0.02). Significant changes in lung compliance were also observed between groups at one-hour (28.2 ± 8.5 mL/cmH2O vs. 40.5 ± 13.9 mL/cmH2O, p = 0.01) and two-hour intervals (26.2 ± 7.8 mL/cmH2O vs. 54.6 ± 16.9 mL/cmH2O, p = 0.01) and at the end of surgery (36.3 ± 9.9 mL/cmH2O vs. 58.2 ± 21.3 mL/cmH2O, p = 0.01). At the end of surgery, plateau pressures remained higher than preoperative values in both groups, but lung compliance remained significantly lower than preoperative values only in patients undergoing RAS with a mean 24% change compared to 1.7% change in the LAS group (p = 0.01). We also noted a more significant arterial to end-tidal CO2 gradient in the RAS group compared to LAS group at one-hour (12.9 ± 4.5 mmHg vs. 7.4 ± 4.4 mmHg, p = 0.02) and two-hours interval (15.2 ± 4.5 mmHg vs. 7.7 ± 4.9 mmHg, p = 0.02), as well as at the end of surgery (11.0 ± 6.6 mmHg vs. 7.0 ± 4.6 mmHg, p = 0.03).ConclusionVideo-assisted surgery is associated with significant changes in lung mechanics after induction of pneumoperitoneum. The observed changes are more severe and longer-lasting in patients undergoing robotic-assisted surgery compared to classic laparoscopy.

Usefulness of Measurement of End-tidal CO2 Using a Portable Capnometer in Patients with Chronic Respiratory Failure Receiving Long-term Oxygen Therapy.

Objective Patients with chronic respiratory failure requiring long-term oxygen therapy (LTOT) are at a risk of CO2 retention because of excessive oxygen administration. The CapnoEye™ is a novel portable capnometer that can measure end-tidal CO2 (EtCO2) noninvasively. This retrospective study evaluated the usefulness of this device. Methods EtCO2 was measured using the CapnoEye™. The EtCO2 and partial pressure of venous carbon dioxide (PvCO2) were analyzed, and other clinical data were assessed. Patients Sixty-one consecutive patients with chronic respiratory failure receiving LTOT in the outpatient department at the Japanese Red Cross Medical Center between July 2017 and March 2018 were retrospectively reviewed. Results There was a significant correlation between EtCO2 and PvCO2 (r=0.63) in the total study population as well as in the COPD group (r=0.65) and ILD group (r=0.67). The PvCO2 and EtCO2 gradient was correlated with only the body mass index in a multivariate analysis (p=0.0235). The EtCO2 levels on the day of admission were significantly higher than those in the same patients when they were in a stable condition (p=0.0049). There was a significant correlation between ΔEtCO2 and ΔPvCO2 (r=0.4). A receiver-operating characteristic curve analysis revealed the optimal cut-off EtCO2 value for identifying hypercapnia to be 34 mmHg (p=0.0005). Conclusion The evaluation of EtCO2 by the CapnoEye™ was useful for predicting PvCO2. The body mass index was identified as a possible predictor of the PvCO2 and EtCO2 gradient. An increase in EtCO2 may indicate deterioration of the respiratory status in patients with chronic respiratory failure receiving LTOT.

Evaluation of end-tidal carbon dioxide gradient as a predictor of volume responsiveness in spontaneously breathing healthy adults

BackgroundMethods to guide fluid therapy in spontaneously breathing patients are scarce. No studies have reported the accuracy of end-tidal CO2 (ET-CO2) to predict volume responsiveness in these patients. We sought to evaluate the ET-CO2 gradient (ΔET-CO2) after a passive leg rise (PLR) maneuver to predict volume responsiveness in spontaneously breathing healthy adults.MethodsWe conducted a prospective study in healthy adult human volunteers. A PLR maneuver was performed and cardiac output (CO) was measured by transthoracic echocardiography. ET-CO2 was measured with non-invasive capnographs. Volume responsiveness was defined as an increase in cardiac output (CO) > 12% at 90 s after PLR.ResultsOf the 50 volunteers, 32% were classified as volume responders. In this group, the left ventricle outflow tract velocity time integral (VTILVOT) increased from 17.9 ± 3.0 to 20.4 ± 3.4 (p = 0.0004), CO increased from 4.4 ± 1.5 to 5.5 ± 1.6 (p = 0.0), and ET-CO2 rose from 32 ± 4.84 to 33 ± 5.07 (p = 0.135). Within the entire population, PLR-induced percentage ∆CO was not correlated with percentage ∆ET-CO2 (R2 = 0.13; p = 0.36). The area under the receiver operating curve for the ability of ET-CO2 to discriminate responders from non-responders was of 0.67 ± 0.09 (95% CI 0.498–0.853). A ΔET-CO2 ≥ 2 mmHg had a sensitivity of 50%, specificity of 97.06%, positive likelihood ratio of 17.00, negative likelihood ratio of 0.51, positive predictive value of 88.9%, and negative predictive value of 80.5% for the prediction of fluid responsiveness.ConclusionsΔET-CO2 after a PLR has limited utility to discriminate responders from non-responders among healthy spontaneously breathing adults.

A study of partial pressure of arterial carbon dioxide and end-tidal carbon dioxide correlation in intraoperative and postoperative period in neurosurgical patients.

Background and Aim:Monitoring carbon dioxide (CO2) is of utmost importance in neurosurgical patients. It is measured by partial pressure of arterial CO2 (PaCO2) and end-tidal CO2 (ETCO2). We aimed to study the correlation between PaCO2 and ETCO2 in neurosurgical patients in the intraoperative and postoperative period on mechanical ventilation in Postanesthesia Care Unit (PACU).Methodology:This was prospective observational study done at tertiary care teaching public hospital over a period of 1 year. We studied 30 patients undergoing elective craniotomy intraoperatively and in the postoperative period on mechanical ventilation for 24 h. Serial measurement of ETCO2 and PaCO2 at baseline, hourly intraoperatively and every 6 hourly in the PACU were studied. Data analysis was done using SPSS software version 20.Results:The mean PaCO2–ETCO2 gradient intraoperatively over 4 h is 3.331 ± 2.856 and postoperatively over 24 h is 2.779 ± 2.932 and lies in 95% confidence interval. There was statistically significant correlation between PaCO2 and ETCO2 intraoperatively baseline, 1 h, 2 h, 3 h, and 4 h with Pearson's correlation coefficients of 0.799, 0.522, 0582, 0.439, and 0.547, respectively (P < 0.05). In PACU at baseline, 6 h, 12 h, 18 h, and 24 h Pearson's correlation coefficients were. 534, −0.032, 0.522, 0.242, 0.592, and 0.547, respectively, which are highly significant at three instances (P < 0.01).Conclusion:ETCO2 correlates PaCO2 with acceptable accuracy in neurosurgical patients in the intraoperative and postoperative period on mechanical ventilation in Intensive Care Unit. Thus, continuous and noninvasive ETCO2 can be used as a reliable guide to estimate arterial PCO2 during neurosurgical procedures and in PACU.

Volumetric capnography: lessons from the past and current clinical applications.

Dead space is an important component of ventilation–perfusion abnormalities. Measurement of dead space has diagnostic, prognostic and therapeutic applications. In the intensive care unit (ICU) dead space measurement can be used to guide therapy for patients with acute respiratory distress syndrome (ARDS); in the emergency department it can guide thrombolytic therapy for pulmonary embolism; in peri-operative patients it can indicate the success of recruitment maneuvers. A newly available technique called volumetric capnography (Vcap) allows measurement of physiological and alveolar dead space on a regular basis at the bedside. We discuss the components of dead space, explain important differences between the Bohr and Enghoff approaches, discuss the clinical significance of arterial to end-tidal CO2 gradient and finally summarize potential clinical indications for Vcap measurements in the emergency room, operating room and ICU.

Predictive value of rapid shallow breathing index in relation to the weaning outcome in ICU patients

BackgroundThe use of indices to predict weaning outcome in type II respiratory failure can avoid premature extubation and unnecessary prolongation of ventilatory support. Rapid shallow breathing index (RSBI) is superior to other measurements for predicting weaning success. Several studies, however, have suggested that RSBI may not have adequate accuracy to be used routinely in the weaning process. Aim of the studyTo study the value of RSBI measured at initiation and termination of a spontaneous breathing trial in predicting weaning outcome for patients with acute on top of chronic type II respiratory failure. Patients and methodsThis study enrolled 84 known cases of COPD who had received mechanical ventilatory support due to acute on top of chronic type II respiratory failure that was evidenced by ABG analysis. They were admitted in the respiratory ICU at Giza Chest Hospital. They were subjected to full history taking, clinical examination, twice daily ABG analysis and A-P chest X-ray. The RSBI measurements were performed in two different ways: 1-with the help of pressure support (PS 10cm H2O; PEEP 5cm H2O), called RSBIpsv for 2h. RSBIpsv was measured at the start (RSBIPS1) and after 2h of trial (RSBIPS2). 2-RSBI was re-measured again using spirometry RSBIsp while patients were breathing spontaneously through T-tube for another 2h. RSBIsp was measured at the start (RSBISP1) and after 2h of trial (RSBISP2). So the total time of the spontaneous breathing trial was 4h. The arterial to end-tidal CO2 gradient was also determined at the end of the 4h SBT and subsequently alveolar dead space was calculated for each patient. Patients were further classified into group 1 (successful weaning n=51) and group 2 (failed weaning n=33). ResultsBinary logistic regression analysis for our results showed that RSBIsp2 (spirometry) and PaCO2−PeCO2 difference were significant predictors of outcome. Since the odds ratio is less than 1 for both predictors (0.971 and 0.715, respectively), lower values of RSBIsp2 (spirometry) and lower values of PaCO2−PeCO2 difference (and hence VD/VT) are more likely to have successful weaning. ConclusionRSBIsp measured through spirometry at the end of SBT is a better predictor of weaning outcome than RSBIpsv measured through pressure support. Our result also reveal that dead space fraction (Vd/Vt) together with PACO2–PECO2 difference are good adjunctive tools for predicting weaning outcome in type II respiratory failure.

End-tidal arterial CO2 partial pressure gradient in patients with severe hypercapnia undergoing noninvasive ventilation.

Patients with severe hypercapnia represent a particularly serious condition in an emergency department (ED), requiring immediate attention. Noninvasive ventilation (NIV) is an integral part of the treatment for acute respiratory failure. The present study aimed to validate the measurement of end-tidal CO2 (EtCO2) as a noninvasive technique to evaluate the effectiveness of NIV in acute hypercapnic respiratory failure. Twenty consecutive patients admitted to the ED with severe dyspnea were enrolled in the study. NIV by means of bilevel positive airway pressure, was applied to the patients simultaneously with standard medical therapy and continued for 12 hours; the arterial blood gases and side-stream nasal/oral EtCO2 were measured at subsequent times: T0 (admission to the ED), T1h (after 1 hour), T6h (after 6 hours), and T12h (after 12 hours) during NIV treatment. The arterial CO2 partial pressure (PaCO2)-EtCO2 gradient decreased progressively, reaching at T6h and T12h values lower than baseline (P < 0.001), while arterial pH increased during the observation period (P < 0.001). A positive correlation was found between EtCO2 and PaCO2 values (r = 0.89, P < 0.001) at the end of the observation period. In our hypercapnic patients, the effectiveness of the NIV was evidenced by the progressive reduction of the PaCO2-EtCO2 gradient. The measurement of the CO2 gradient could be a reliable method in monitoring the effectiveness of NIV in acute hypercapnic respiratory failure in the ED.

Fatal pulmonary thromboembolism during total hip replacement under spinal anesthesia

Fatal pulmonary thromboembolism during total hip replacement under spinal anesthesia

Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study

BackgroundAs differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2) uptake significantly differed in these diseases when compared to the thermodilution technique.MethodSingle-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients.ResultsIn PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients.ConclusionCardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.

Arterial to end-tidal CO2 gradient reversal during laparoscopic pheochromocytoma resection

Arterial to end-tidal CO2 gradient reversal during laparoscopic pheochromocytoma resection

Pigs are not a reliable experimental model in the study of the haemodynamic and respiratory effects of CO2 pneumoperitoneum.

Haemodynamic and respiratory effects of a CO2 pneumoperitoneum (intra-abdominal pressure = 12 mmHg) associated to a head-up position(15 degrees ) were studied in 20 pigs using a Swan-Ganz catheter and the Single Breath Test for CO2. The pneumoperitoneum induced a moderate rise in mean arterial pressure (+17%) (P<0.001) without any variation in heart rate, cardiac output and systemic vascular resistances. The following respiratory effects were observed: an increase in PaCO2 (+20%) (P<0.001), PE'CO2 (+31%) (P<0.001), expired volume of CO2 (+28%) (P<0.001), arterial to end-tidal CO2 gradient (+80%) (P<0.001) and alveolar dead space (+40%) (P<0.001) occured. Alveolar ventilation remained stable. Finally and contrary to healthy human patient, intraperitoneal CO2 insufflation in pig induced slight haemodynamic changes and major respiratory modifications. Thus, our data do not support the conclusion that the pig is a reliable experimental model for studying the pathophysiology of CO2 pneumoperitoneum-induced changes in haemodynamic and respiratory parameters, in human patients.

Capnography Monitoring During Neurosurgery

In neurosurgery, estimation of PaCO2 from PETCO2 has been questioned. The aim of this study was to reevaluate the accuracy of PETCO2 in estimating PaCO2 during neurosurgical procedures lasting >3 h and to measure the effect of surgical positioning on arterial to end-tidal CO2 gradient (P[a-ET]CO2) over time. One hundred four neurosurgical patients classified into four groups (supine [SP], lateral [LT], prone [PR], sitting [ST]) were included in a prospective study. PaCO2, PETCO2, and P(a-ET)CO2 were measured after induction of anesthesia (T0), after positioning (T1), each following hour (T2, T3, T4), and at the end of the procedure after return to the SP position (T5). Data are expressed as the mean +/- SD, and statistical analysis used linear regression, the Bland-Altman method, and analysis of variance. The mean durations of positioning and surgery were 4.1+/-1 h and 3.7+/-1.3 h, respectively. We performed 624 simultaneous measurements of PaCO2 (33+/-5 mm Hg) and PETCO2 (27+/-4 mm Hg), leading to a mean P(a-ET)CO2 of 6+/-4 mm Hg. P(a-ET)CO2 of the LT group (7+/-3 mm Hg) was larger (compared with the SP, PR, and ST groups) because of a lower PETCO2 (26+/-4 mm Hg). Negative P(a-ET)CO2 (PETCO2 > PaCO2) occurred 22 times, only in the SP (n = 9) and ST groups (n = 13). Changes in opposite directions of PETCO2 and PaCO2 between two successive measurements were found in 26% of the cases. Correlation coefficients in the four groups (PaCO2 versus PETCO2) were not in good agreement (0.46 to 0.62; P < 0.001). The mean bias was between 5 and 7 mm Hg. The superior (13-15 mm Hg) and inferior (-5 to 0 mm Hg) limits of agreement were too large to expect PETCO2 to replace PaCO2. In conclusion, during neurosurgical procedures of >3 h, capnography should be performed with regular analysis of arterial blood gases for optimal ventilator adjustment. This study, which aimed to reevaluate the ability of PETCO2 to estimate PaCO2 during neurosurgical procedures according to surgical position, indicates that PETCO2 cannot replace PaCO2 for the following reasons: scattering of individual values; occurrence of negative arterial to end-tidal CO2 gradient (P[a-ET]CO2; PaCO2 and PETCO2 variations in opposite directions; large changes in P(a-ET)CO2 between two samples; and instability of P(a-ET)CO2 over time.

Noninvasive monitoring of end-tidal CO2 via nasal cannulas in spontaneously breathing children during the perioperative period

Objective: To determine the correlation between end-tidal CO2 and Paco2 values measured via nasal cannulas in spontaneously breathing children during the perioperative period. Design: Prospective evaluation. Setting: Pediatric intensive/intermediate care unit in a tertiary care referral center. Patients: Thirty postoperative surgical and trauma patients aged ≤18 yrs (average age 7.8 yrs [range 6 months to 16 yrs] and average weight 28.3 kg (range 8.5 to 69). Measurements and Main Results: Spontaneously breathing, nonintubated patients with an arterial cannula in place were selected for study. End-tidal CO2 was sampled from nasal cannulas by a sidestream aspirator and was estimated by infrared spectroscopy. The difference between Paco2 and end-tidal CO2 was compared using linear regression analysis. A total of 55 blood gas measurements were obtained on the 30 patients. The Paco2 to end-tidal CO2 gradient was ≤4 torr in 54 of the 55 samples. The mean Paco2 was 39.5 ± 3.3 torr (5.27 ± 0.44 kPa) with a mean end-tidal CO2 value of 39.7 ± 3.8 torr (5.29 ± 0.51 kPa). Linear regression analysis of arterial vs. end-tidal CO2 yielded a slope of 0.992 andp= .0001. Conclusions: End-tidal CO2 measurement by infrared spectroscopy provided an accurate estimation of Paco2 in this patient population. Its use may limit the need for invasive monitoring and/or repeated arterial blood gas analysis. (Crit Care Med 1994; 22:1805–1808)

Noninvasive monitoring of end-tidal CO2 via nasal cannulas in spontaneously breathing children during the perioperative period

To determine the correlation between end-tidal CO2 and PaCO2 values measured via nasal cannulas in spontaneously breathing children during the perioperative period. Prospective evaluation. Pediatric intensive/intermediate care unit in a tertiary care referral center. Thirty postoperative surgical and trauma patients aged < or = 18 yrs (average age 7.8 yrs [range 6 months to 16 yrs] and average weight 28.3 kg (range 8.5 to 69). Spontaneously breathing, nonintubated patients with an arterial cannula in place were selected for study. End-tidal CO2 was sampled from nasal cannulas by a sidestream aspirator and was estimated by infrared spectroscopy. The difference between PaCO2 and end-tidal CO2 was compared using linear regression analysis. A total of 55 blood gas measurements were obtained on the 30 patients. The PaCO2 to end-tidal CO2 gradient was < or = 4 torr in 54 of the 55 samples. The mean PaCO2 was 39.5 +/- 3.3 torr (5.27 +/- 0.44 kPa) with a mean end-tidal CO2 value of 39.7 +/- 3.8 torr (5.29 +/- 0.51 kPa). Linear regression analysis of arterial vs. end-tidal CO2 yielded a slope of 0.992 and p = .0001. End-tidal CO2 measurement by infrared spectroscopy provided an accurate estimation of PaCO2 in this patient population. Its use may limit the need for invasive monitoring and/or repeated arterial blood gas analysis.

A randomised controlled study comparing bromocriptine to which levodopa was later added, with levodopa alone in previously untreated patients with Parkinson's disease: a five year follow up.

This pilot study was performed to compare the occurrence of long term motor complications in Parkinson's disease when the introduction of levodopa was delayed by an initial treatment with high doses of bromocriptine alone. The trial was a prospective randomised controlled study comparing 31 previously untreated patients with Parkinson's disease initially given bromocriptine alone to which levodopa was later added (group B/D) and 29 other previously untreated patients with Parkinson's disease immediately given levodopa alone (group D). The end point was the occurrence of the first motor complications (wearing off or dyskinesia). Group B/D patients received bromocriptine (52 (SEM 5) mg/day) for 2.7 years, to which levodopa was later added (471 (SEM 46) mg/day). Group D patients received a comparable dose of levodopa alone (569 (SEM 47) mg/day). Both had similar disability scores at the end of the study. Motor complications were fewer and appeared later in group B/D than in group D (56% after 4.9 (SEM 0.5) years of treatment v 90% after 2.7 (SEM 0.5) years, p < 0.01). Wearing off appeared later (p < 0.01) in group B/D (4.5 (SEM 0.6) years) than in group D (2.9 (SEM 0.6) years). Peak dose dyskinesia occurred less often in group B/D patients (three v 14 cases, p < 0.01). This study showed that a three year initial monotherapy with high doses of bromocriptine followed by addition of levodopa delayed the occurrence of long term motor complications usually found in patients with Parkinson's disease treated with levodopa alone from the beginning.

Hypercarbia during carbon dioxide pneumoperitoneum

Patients with cardiopulmonary insufficiency undergoing laparoscopic surgery with carbon dioxide (CO2) pneumoperitoneum may retain CO2 resulting in clinically significant respiratory acidosis. A canine model of pulmonary emphysema induced by papain inhalation was utilized to evaluate the respiratory effects of both CO2 and helium pneumoperitoneum. Prior to papain inhalation and 5 and 8 weeks after initial treatment under general anesthesia, mechanical ventilation was adjusted to maintain the end-tidal CO2 (ETCO2) at 40 mm Hg during baseline and pneumoperitoneum physiologic monitoring periods. Utilizing an analysis of variance, hemodynamic and respiratory physiologic parameters were compared. In this canine model, all dogs demonstrated consistent hypercarbia during CO2 pneumoperitoneum prior to papain treatments, but CO2 retention was significantly increased in the emphysematous state. The occurrence of hypercarbia during CO2 pneumoperitoneum may be underestimated by ETCO2 monitoring as was revealed by an increased PaCO2 (arterial carbon dioxide pressure)-ETCO2 gradient with an increasing time interval between papain exposure and period of physiologic monitoring. Irrespective of the pulmonary condition of the dog, helium pneumoperitoneum did not produce any hypercarbic or acidic changes when compared with the concomitant baseline period of dogs prior to the induction of pneumoperitoneum, thus suggesting that helium pneumoperitoneum may be a reasonable alternative in patients at risk for CO2 retention.

Components of the respiratory dead space and their variation with pressure breathing and with bronchoactive drugs.

ARTICLESComponents of the Respiratory Dead Space and Their Variation With Pressure Breathing and With Bronchoactive DrugsB. Folkow, and J. R. PappenheimerB. Folkow, and J. R. PappenheimerPublished Online:01 Jul 1955https://doi.org/10.1152/jappl.1955.8.1.102MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEffect of pulmonary perfusion on the slopes of single-breath test of CO2G. Tusman, M. Areta, C. Climente, R. Plit, F. Suarez-Sipmann, M. J. Rodríguez-Nieto, G. Peces-Barba, E. Turchetto, and S. H. Böhm1 August 2005 | Journal of Applied Physiology, Vol. 99, No. 2Estimating Alveolar Dead Space from the Arterial to End-Tidal CO2 Gradient: A Modeling AnalysisAnesthesia & Analgesia, Vol. 97, No. 6Constancy of physiological dead space during high-frequency ventilationRespiration Physiology, Vol. 47, No. 1Histamine and phenyldiguanide induced tachypnea in hypercapnia and hypoxiaRespiration Physiology, Vol. 36, No. 2Gas exchange after pulmonary thromboemoblization in dogs.Circulation Research, Vol. 42, No. 1Breathing during sleep and wakefulness in the catRespiration Physiology, Vol. 30, No. 3Control mechanisms determining rate and depth of respiratory movementsRespiration Physiology, Vol. 10, No. 1Respiration of the ox: Normal values and the effects of exposure to hot environmentsRespiration Physiology, Vol. 4, No. 3Alveolar-arterial gas tension relationships in acute anterior poliomyelitisThe American Journal of Medicine, Vol. 30, No. 6TEST FOR PULMONARY EMBOLISMThe Lancet, Vol. 273, No. 7082PAIN IN THE SHOULDERThe Lancet, Vol. 273, No. 7082 More from this issue > Volume 8Issue 1July 1955Pages 102-110 https://doi.org/10.1152/jappl.1955.8.1.102PubMed13242498History Published online 1 July 1955 Published in print 1 July 1955 Metrics