Mean End-tidal Carbon Dioxide Research Articles

Transnasal humidified rapid insufflation ventilatory exchange (THRIVE): A game changer in apnoeic anaesthesia for shared airway procedures – A retrospective study

Background and Aims: Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) is a valuable adjunct during apnoea. Conventional techniques of apnoeic anaesthesia have limitations. THRIVE helps to maintain oxygenation during the apnoeic periods in tubeless airway surgeries. We aimed to evaluate tubeless apnoeic anaesthesia in shared airways using THRIVE to determine safe apnoea time. Methods: Two years of retrospective data were collected at a tertiary care centre, which included 60 patients in whom THRIVE was used for apnoeic anaesthesia. We appraised tubeless apnoeic anaesthesia in shared airways using THRIVE to determine safe apnoea time. Data on oxygenation, haemodynamic parameters, ventilation and the perioperative course were also collected. The data were analysed using GNU PSPP 1.0.1 software. Results: The patients’ mean age was 48.53 [standard deviation (SD):16.62] years. Microlaryngoscopy [24 (40%)], rigid bronchoscopy [12 (20%)], tracheal dilatation [12 (20%)] and foreign body removal [8 (13.3%)] were the common procedures. The mean apnoea time was 14.5 (SD: 2.05) min. Patients maintained normal haemodynamic parameters, with a mean oxygen saturation of 98% during apnoea. The highest mean end-tidal carbon dioxide at the end of apnoea was 55 mmHg, which normalised after 1–2 min of ventilation. Intermittent ventilation was done in eight patients as the apnoea time exceeded 20 min. Emergence and recovery were smooth, and none of the patients developed any complications throughout the procedure. Conclusion: THRIVE can be effectively and safely used for tubeless apnoeic anaesthesia, with an uninterrupted apnoea time of approximately 15 min without complications.

Association of small adult ventilation bags with return of spontaneous circulation in out of hospital cardiac arrest

IntroductionLittle is known about the impact of tidal volumes delivered by emergency medical services (EMS) to adult patients with out-of-hospital cardiac arrest (OHCA). A large urban EMS system changed from standard adult ventilation bags to small adult bags. We hypothesized that the incidence of return of spontaneous circulation (ROSC) at the end of EMS care would increase after this change. MethodsWe performed a retrospective analysis evaluating adults treated with advanced airway placement for nontraumatic OHCA between January 1, 2015 and December 31, 2021. We compared rates of ROSC, ventilation rate, and mean end tidal carbon dioxide (ETCO2) by minute before and after the smaller ventilation bag implementation using linear and logistic regression. ResultsOf the 1,994 patients included, 1,331 (67%) were treated with a small adult bag. ROSC at the end of EMS care was lower in the small bag cohort than the large bag cohort, 33% vs 40% (p = 0.003). After adjustment, small bag use was associated with lower odds of ROSC at the end of EMS care [OR 0.74, 95% CI 0.61 – 0.91]. Ventilation rates did not differ between cohorts. ETCO2 values were lower in the large bag cohort (33.2 ± 17.2 mmHg vs. 36.9 ± 19.2 mmHg, p < 0.01). ConclusionUse of a small adult bag during OHCA was associated with lower odds of ROSC at the end of EMS care. The effects on acid base status, hemodynamics, and delivered minute ventilation remain unclear and warrant additional study.

One-person versus two-person mask ventilation in preterm infants at birth: a pilot randomised controlled trial

BackgroundMask leak and airway obstruction are common with mask ventilation in newborn infants, leading to suboptimal ventilation. We aimed to perform a pilot study measuring respiratory mechanics during one-person and...

A Pilot Study of End-Tidal Carbon Dioxide in Prediction of Inhospital Cardiac Arrests.

Objectives:A validated means to predict inhospital cardiac arrest is lacking. The purpose of this study was to evaluate the changes in end-tidal carbon dioxide, as it correlates with the progression to inhospital cardiac arrest in ICU patients.Design, Setting, and Patients:Single-center, retrospective cohort study of mechanically ventilated ICU patients (age > 18 yr old) having inhospital cardiac arrest with advanced cardiac life support and continuous end-tidal carbon dioxide monitoring at a single academic center from 2014 to 2017. Demographics, clinical variables, and outcomes were collected. End-tidal carbon dioxide was collected from 5 to 2,880 minutes before inhospital cardiac arrest. Data were analyzed using descriptive statistics, and model estimates were generated using a repeated-measures categorical model with restricted maximum likelihood estimation and fully specified (autoregressive) covariance to assess the effect of time on changes in end-tidal carbon dioxide.Measurements and Main Results:A total of 788 patients were identified and 104 met inclusion criteria, where 62% were male with an average age of 58.5 years. Seventy-four percent required vasopressors and 72% experienced pulseless electrical activity. Mean end-tidal carbon dioxide 5 minutes prior to inhospital cardiac arrest was significantly lower than all evaluated time points except 180 minutes (p < 0.05). One patient survived to hospital discharge. In multivariate logistic regression modeling for return of spontaneous circulation, a greater change in the prearrest end-tidal carbon dioxide maximum to prearrest end-tidal carbon dioxide minimum was associated with a decreased likelihood of return of spontaneous circulation (odds ratio 0.903; 95% CI, 0.832–0.979; p = 0.014). Additionally, a change from prearrest end-tidal carbon dioxide maximum to prearrest end-tidal carbon dioxide minimum greater than 17 mm Hg was associated with a decreased likelihood of return of spontaneous circulation and odds ratio 0.150; 95% CI, 0.036–0.66; p = 0.012).Conclusions:Mean end-tidal carbon dioxide is significantly lower immediately before inhospital cardiac arrest. The statistical and clinical significance of end-tidal carbon dioxide may highlight its utility for predicting inhospital cardiac arrest in ICU patients. Comparison analysis and modeling explorations in a larger cohort are needed.

Adapting re-usable elastomeric respirators to utilise anaesthesia circuit filters using a 3D-printed adaptor - a potential alternative to address N95 shortages during the COVID-19 pandemic.

SummaryThe COVID‐19 pandemic has increased the demand for disposable N95 respirators. Re‐usable elastomeric respirators may provide a suitable alternative. Proprietary elastomeric respirator filters may become depleted as demand increases. An alternative may be the virus/bacterial filters used in anaesthesia circuits, if they can be adequately fitted onto the elastomeric respirators. In addition, many re‐usable elastomeric respirators do not filter exhaled breaths. If used for sterile procedures, this would also require modification. We designed a 3D‐printed adaptor that permits elastomeric respirators to interface with anaesthesia circuit filters and created a simple modification to divert exhaled breaths through the filter. We conducted a feasibility study evaluating the performance of our modified elastomeric respirators. A convenience sample of eight volunteers was recruited. Quantitative fit testing, respiratory rate and end‐tidal carbon dioxide were recorded during fit testing exercises and after 1 h of wear. All eight volunteers obtained excellent quantitative fit testing throughout the trial. The mean (SD) end‐tidal carbon dioxide was 4.5 (0.5) kPa and 4.6 (0.4) kPa at baseline and after 1 h of wear (p = 0.148). The mean (SD) respiratory rate was 17 (4) breaths.min−1 and 17 (3) breaths.min−1 at baseline and after 1 h of wear (p = 0.435). Four out of eight subjects self‐reported discomfort; two reported facial pressure, one reported exhalation resistance and one reported transient dizziness on exertion. Re‐usable elastomeric respirators to utilise anaesthesia circuit filters through a 3D‐printed adaptor may be a potential alternative to disposable N95 respirators during the COVID‐19 pandemic.

Prophylactic Effects of Intravenous Dexamethasone and Lidocaine on Attenuating Hemodynamic-Respiratory and Pain Complications in Children Undergoing Cleft Palate Repair Surgery With General Anesthesia

This study aimed to compare the prophylactic effects of intravenous (IV) dexamethasone and lidocaine on hemodynamic condition, respiratory complications, pain control, and vomit incidence following cleft palate repair surgery. This double-blind randomized controlled trial was carried out on 87 children assigned to three groups. Prior to anesthesia, subjects in groups D and L received 0.2 and 1 mg/kg IV dexamethasone and lidocaine, respectively. Moreover, group C received placebo in a similar condition. The outcome variables were recorded prior to the surgery and then every 15 minutes during the surgical and recovery time. Mean heart rate (HR), mean arterial blood pressure (MABP), and mean end-tidal carbon dioxide (ETCO2) during the surgical time were not significantly different between dexamethasone and lidocaine groups. Dexamethasone significantly improved the level of blood oxygen saturation (SPO2) during the recovery time. Nevertheless, MABP in recovery time did not significantly decrease in the dexamethasone group. There were no significant differences in respiratory complications, pain score, and vomiting incidence between lidocaine and dexamethasone groups. Premedication with both IV dexamethasone and lidocaine provided similar stable hemodynamic and respiratory conditions during the surgical time. However, the use of dexamethasone developed more desirable effects on HR and SPO2 than administration of lidocaine during the recovery time. Both drugs significantly lessened postoperative pain compared to the placebo group at this time.

EVALUATION AND INITIATION OF SPEAKING VALVES IN CHILDREN WITH TRACHEOSTOMIES

SESSION TITLE: Pediatrics SESSION TYPE: Original Investigations PRESENTED ON: 10/20/2019 2:15 PM - 3:15 PM PURPOSE: Numerous benefits have been proposed for speaking valve use in individuals with tracheostomy tubes, including communication and secretion management. Despite this, they remain underutilised with evidence based criteria to assess candidacy lacking in the pediatric population. The aim of our study was to review the prior use of speaking valves and evaluate eligibility for initiation of use in children with tracheostomies. METHODS: We performed a cross-sectional retrospective study. Pediatric patients with tracheostomy tubes seen in our Tracheostomy Education and Communication at Home (TEACH) Clinic at the Hospital for Sick Children, Toronto, Ontario, Canada were included. Data was collected on patients seen between May 1, 2016 and March 7, 2019. RESULTS: Thirty-four participants were included in the study; twenty (59%) were male. The mean (standard deviation, SD) cohort age was 5.61 (4.93) years. The mean (SD) time since tracheostomy insertion was 3.08 (3.36) years. The reason for tracheostomy insertion was: long-term ventilation (n=17 (50%)); pulmonary hygiene (n=4 (12%)); and upper airway obstruction (n=13 (38%)). Only 15 (44%) had a speaking valve or had previously been assessed for one. Mean (SD) oxygen saturation (SpO2) was 98% (1.8) and mean (SD) end-tidal carbon dioxide (etCO2) was 38.5 mmHg (5.45) for the cohort. Trans-tracheal pressure was documented in 23 patients with 13 (57%) having pressures ≤ 10 cmH2O, 6 (26%) with pressures 11-20 cmH2O, and 4 (17%) with pressures > 20 cmH2O. Thirteen (38%) patients were newly initiated on the speaking valve, with 2 requiring downsize of the tracheostomy tube to achieve trans-tracheal pressures ≤ 20 cmH2O. CONCLUSIONS: Based on our results, clinicians are missing earlier opportunities to initiate a speaking valve in children with tracheostomy tubes. Further studies are required to systematically evaluate the long-term impact of speaking valves in children with tracheostomies. CLINICAL IMPLICATIONS: Thorough clinical evaluations in conjunction with objective data including SpO2, etCO2, and trans-tracheal pressures are useful in determining candidacy for speaking valve use. DISCLOSURES: No relevant relationships by Reshma Amin, source=Web Response No relevant relationships by Jackie Chiang, source=Web Response No relevant relationships by Laurie Russell, source=Web Response No relevant relationships by Faiza Syed, source=Web Response No relevant relationships by Nikolaus Wolter, source=Web Response

A pilot study evaluating the utility of a novel tube cricothyrotomy technique in providing ventilation in small animals using a live porcine model.

BackgroundTube cricothyrotomy has been suggested as a first-choice for emergency surgical airway access in small animals, rather than the more commonly accepted procedures of tracheotomy and needle cricothyrotomy.MethodsA small pilot study of tube cricothyrotomy in a live porcine model was conducted to evaluate this method. The technique was modified to permit the use of commonly available equipment and ease of application. Following ethics approval, a tube cricothyrotomy was performed on 9 live pigs. The endpoints were the efficacy of ventilation through the tube as measured by end-tidal carbon dioxide, successful placement of the tube and the time taken for placement.ResultsOf the nine pigs, eight had a tube placed successfully, with the median procedure time being 111.5 seconds (range: 35–240 seconds). After 10 mins, the mean end-tidal carbon dioxide was 58.3 mmHg (95% CI: 55.2–61.3 mmHg), with a range of 54–64 mmHg. Tube cricothyrotomy holds promise as a means of rapidly obtaining tracheal access in small animals and temporarily sustaining ventilation in an emergency.ConclusionFurther detailed investigation is warranted to assess the use of this technique in the small animal emergency setting.

Apneic Oxygenation During Prolonged Laryngoscopy in Obese Patients: a Randomized, Double-Blinded, Controlled Trial of Nasal Cannula Oxygen Administration.

Obese patients have a propensity to desaturate during induction of general anesthesia secondary to their reduced functional residual capacity and increased oxygen consumption. Apneic oxygenation can provide supplemental oxygen to the alveoli, even in the absence of ventilation, during attempts to secure the airway. In this study, we hypothesized that oxygen administration through a nasopharyngeal airway and standard nasal cannula during a simulated prolonged laryngoscopy would significantly prolong the safe apneic duration in obese patients. One hundred thirty-five obese patients undergoing non-emergent surgery requiring general anesthesia were randomized to either the control group or to receive apneic oxygenation with air versus oxygen. All patients underwent a standard intravenous induction. For patients randomized to receive apneic oxygenation, a nasopharyngeal airway and standard nasal cannula were inserted. A simulated prolonged laryngoscopy was performed to determine the duration of the safe apneic period, defined as the beginning of laryngoscopy until the peripheral oxygen saturation (SpO2) reached 95%. The oxygen group had a median safe apneic duration that was 103s longer than the control group. The lowest mean SpO2 value during the induction period was 3.8% higher in the oxygen group compared to the control group. Following intubation, patients in the oxygen group had a mean end tidal carbon dioxide (ETCO2) level that was 3.0mmHg higher than patients in the control group. In obese patients, oxygen insufflation at 15L/min through a nasopharyngeal airway and standard nasal cannula can significantly increase the safe apneic duration during induction of anesthesia.

Sleep study indices and early post-tonsillectomy outcomes

ObjectivesTo investigate the relationships between preoperative sleep study findings of children undergoing adenotonsillectomy anesthesia emergence time, recovery room time, and length of stay. Study designRetrospective case series with chart review. SettingTertiary care children's hospital. Subjects and methodsAll children aged 1–17 years who had undergone adenotonsillectomy between 2013 and 2016 were included. Apnea-hypopnea index (AHI), central apnea index (CAI), oxygen saturation nadir, and end-tidal carbon dioxide were compared with the in-operating room times, recovery room time, and length of stay. ResultsThree hundred and fourteen patients with a mean age of 6.67 (95% CI 6.25–7.09) years were included. Mean AHI was 9.14 (95% CI 7.33–10.95), mean CI was 0.88 (95% CI 0.50–1.26), mean oxygen saturation nadir was 82.9% (95% CI 81.41–84.32), mean end-tidal carbon dioxide was 50.3 (95% CI 49.39–51.15). Mean emergence time was 16 min (95% CI 15:11–17:13 min), recovery room time was 66 min (95% CI 1:00–1:11 h), and length of stay was 25.7 h (95% CI 21:43–30:00 h).When controlled for age, gender and BMI, linear regression showed that children with a higher AHI had a significantly longer operating room and operative times (p < 0.001), emergence time (p < 0.001) and length of stay (p = 0.01). CAI was related to shorter total operating room times (p = 0.03). AHI, oxygen saturation nadir, CAI and end-tidal carbon dioxide were not associated with recovery room time. ConclusionPreoperative sleep study indices are associated with longer in-operating room times and length of stay, and can be useful in planning operating room and hospital flow.

Reliability of cerebral oximeter in non-invasive diagnosis and follow-up of hypercapnia

In this study, aimed to evaluate the sensitivity and specificity of cerebral oximetry and EtCO2 values in non-invasive diagnosis and monitoring of hypercapnia. This study enrolled pediatric patients admitted to and mechanically ventilated at the Pediatric Intensive Care Unit of Gaziantep University Faculty of Medicine Hospital between January 2014 and January 2015. Patients' age, gender, diagnosis, ventilatory parameters, a measured of the mean end-tidal carbon dioxide value stream method, and the simultaneously monitored arterial blood gas PaCO < sub > 2 < /sub > level and near infrared spectroscopy device (NIRS) measurements were recorded. The mean age of patients was 61 months (min 4-max 193), and there were 8 (53.4%) female and 7 (46.6%) male subjects. A significant correlation was found between PCO2 and NIRS, PCO < sub > 2 < /sub > and EtCO < sub > 2 < /sub > (r = 0.571, p < 0.001). There was a significant positive correlation between EtCO2 and NIRS (r = 0.479, p < 0.001). NIRS levels were significantly higher (p < 0.001) in the group with pCO < sub > 2 < /sub > > 45; EtCO < sub > 2 < /sub > > 40 and pH < 7.35, compared to the group with PCO < sub > 2 < /sub > < 45 EtCO < sub > 2 < /sub > < 40 and ph≥7.35 . The best cut-off point for NIRS to distinguish the groups with PCO < sub > 2 < /sub > > 45 with PCO < sub > 2 < /sub > < 45 was 80.5, with a sensitivity of 65.3%, specificity of 84.3%, and positive and negative predictive values of 81.9% and 69.1%, respectively. The best cut-off point for NIRS to distinguish the groups with EtCO < sub > 2 < /sub > > 40 and EtCO < sub > 2 < /sub > < 40 was 81, with a sensitivity of 62.2%, specificity 77.9%, and positive and negative predictive values of 61.2% and 72.3%, respectively. As for pH < 7.35 and PaCO < sub > 2 < /sub > > 45, while sensitivity of EtCO < sub > 2 < /sub > (at a cut-off point of 40) was 64.9%; the sensitivity of NIRS (at a cut-off point of 80.5) was 28.1%, with EtCO < sub > 2 < /sub > being significantly more sensitive than NIRS (p < 0.001). The results of the present study suggest that NIRS values of above 80 should alert clinicians for hypercapnia associated with increased cerebral blood flow.

The first 100 infant thoracoscopic lobectomies: Observations through the learning curve and comparison to open lobectomy

ObjectiveThe objective of the study is to describe our initial 100 attempted infant thoracoscopic lobectomies for asymptomatic, prenatally diagnosed lung lesions, and compare the results to contemporaneous age-matched patients undergoing open lobectomy. BackgroundInfant thoracoscopic lobectomy is a technically challenging procedure, which has only gained acceptance worldwide in recent years. MethodsThis is a retrospective review of all patients undergoing thoracoscopic or open lung lobectomy between March 2005 and January 2014. Included were all asymptomatic infants younger than 4months. Excluded were patients undergoing emergent lobectomy and patients with isolated extralobar bronchopulmonary sequestrations. ResultsA total of 100 attempted thoracoscopic lobectomies were compared with 188 open lobectomies. In the thoracoscopic group, mean age and weight at surgery were 7.3weeks and 4.8kg, mean operative time was 185minutes, and mean hospital stay was 3days. Twelve cases were converted to open (12%). Ten conversions occurred within the first third of the series and none in the last third. There were no mortalities. There were no differences between the thoracoscopic and open groups in perioperative complications or hospital stay. There was a significant difference in the operative time: 111minutes vs. 185minutes (open vs. thoracoscopic; p<0.001). There was a higher mean end-tidal carbon dioxide (ETCO2) and lower mean peripheral capillary oxygen saturation (SpO2) in the thoracoscopic group versus the open group (51.7 versus 38.6mmHg and 97.5 versus 99.1%, respectively). ConclusionIn high volume centers, the learning curve of thoracoscopic lobectomy can be overcome and the procedure can be performed with equivalent outcomes and, in our opinion, superior cosmetic results to open lobectomy.

Effect of Endotracheal Suctioning with and without Normal Saline on Hemodynamic and Respiratory Parameters in Patients Undergoing Mechanical Ventilation in ICU of Hospitals Supervised by Guilan University of Medical Sciences

Airway suction is one of the most popular methods for drainage airways in patients with artificial airway; thus, correct suction of airways is important. Hence, the purpose of this study is to determine the effects of suction methods with and without normal saline on hemodynamic and respiratory patients. This randomized crossover clinical trial was conducted on two groups consisting of 37 mechanically ventilated patients by suctioning with and without normal saline. After at least 2 hours, the second stage was conducted and the patients were displaced in groups A and B. respiratory and hemodynamic parameters were measured at different intervals. The average age of patients was 21.8 ± 51.2; in terms of consciousness, 70% of patients were Sedate. Systolic blood pressure (P = 0.20), diastolic blood pressure (P <0.0001), average arterial pressure (P <0.0001) and heart rate (P <0.0001) increased over time immediately after the suction and then declined; in approximately 5 minutes after suction, it approached its baseline. This difference was significant in other cases except for systolic blood pressure. The mean respiratory rate, mean airway pressure, mean oxygen-saturated haemoglobin, mean end-tidal carbon dioxide were similar in both suction groups with and without normal saline during different time steps and no significant differences were observed. As long as there is no sufficient evidence to use normal saline on endotracheal suctioning, this method is not recommended to be used routinely. It is recommended to substitute strategies such as airway hydration, adequate hydration of patients, early mobilization of patients and administration of mucolytic drugs.

Cardiorespiratory Effects of Balancing PEEP With Intra-abdominal Pressures During Laparoscopic Cholecystectomy

Applying appropriate positive end-expiratory pressure (PEEP) to corresponding intra-abdominal pressure (IAP) can improve gas exchange during capnoperitoneum without any hemodynamic effects. A total of 75 patients were randomly allocated to group 0PEEP (n=25), group 5PEEP (n=25), and group 10PEEP (n=25) according to the level of PEEP, in whom capnoperitoneum was created with IAP of 14, 8, and 14 mm Hg, respectively. Hemodynamic and respiratory parameters were recorded up to 30 minutes after capnoperitoneum. In 0PEEP group, mean end-tidal carbon dioxide demonstrated significant rise 2 minutes after capnoperitoneum and plateaued at about 15 minutes but remained at high level for up to 30 minutes when compared with the 5PEEP and 10PEEP groups (P<0.05). Correspondingly, the mean PaCO2 (48.0±4.1 mm Hg) for the 0PEEP group was higher at 30 minutes when compared with 5PEEP (37.8±2.7 mm Hg) and 10PEEP (37.2±3.9 mm Hg) groups. The oxygenation was better preserved in 5PEEP and 10PEEP groups with significantly higher PaO2/Fio2 ratio. Heart rate, mean arterial pressure, and cardiac output remained stable throughout the study in all the 3 groups. Application of appropriate PEEP corresponding to the IAP helped maintain CO2 elimination and improved oxygenation without any hemodynamic disturbance in patients undergoing laparoscopic cholecystectomy.

Postoperative respiratory and analgesic effects of dexmedetomidine or morphine for adenotonsillectomy in children with obstructive sleep apnoea

The postoperative respiratory and analgesic effects of dexmedetomidine and morphine have not been compared in children with sleep apnoea having adenotonsillectomy. In a randomised double-blind study we recruited 60 children, aged 2-13 years, who received either intravenous dexmedetomidine 1 μg.kg(-1) or morphine 100 μg.kg(-1) on anaesthetic induction. End-tidal carbon dioxide, Children's Hospital of Eastern Ontario Pain Scale score and supplementary morphine administration were recorded every 15 min for 60 min postoperatively. Over 60 min, mean (SD) end-tidal carbon dioxide was consistently lower with dexmedetomidine compared with morphine (5.4 (0.7) kPa vs 6.0 (0.6) kPa, respectively; p = 0.001). Mean (SD) pain scores were higher with dexmedetomidine (8.1 (2.0) immediately postoperatively and 6.7 (1.0) at 60 min vs 7.6 (1.8) and 6.3 (0.7), respectively, with morphine (p = 0.023)). More patients required supplementary morphine with dexmedetomidine (13/30 (43%) vs 21/30 (70%); p = 0.037). Postoperatively, dexmedetomidine produced less respiratory depression than morphine, but less effective analgesia.

Intraoperative carbon dioxide management and outcomes

Intraoperative hyperventilation to induce hypocapnia has historically been common practice and has physiological effects that may be detrimental. In contrast, hypercapnia has effects that may be beneficial. As these effects may influence postoperative recovery, we investigated the association between variations in intraoperative carbon dioxide and length of hospital stay in patients who had elective colon resections and hysterectomies. Data were extracted from electronic records for elective colon resections and hysterectomies done from 2002 to 2008. Patients were divided into four groups based on surgical procedure and use of laparoscopic technique. Parameters extracted for analysis included mean end-tidal carbon dioxide (EtCO2) during the surgical procedure as well as others previously purported to affect postoperative outcomes. In-hospital length of stay (LOS) was determined from administrative records and was used as the independent outcome variable. For each group, Poisson regression analysis was performed to find factors that were independently associated with the outcome. A total of 3421 case records in our database met inclusion criteria. Median EtCO2 was 31 mmHg. Median LOS was 7 and 5 days for open and laparoscopic colon resections, and 3 and 2 days for open and laparoscopic hysterectomies, respectively. Regression analysis revealed a statistically significant independent association between higher EtCO2 and reduced LOS for colon resection and open hysterectomy. There is a significant association between higher intraoperative EtCO2 and shorter LOS after colon resection and open hysterectomy. The common practice of inducing hypocapnia may be deleterious, and maintaining normocapnia or permitting hypercapnia may improve clinical outcomes.

Physiologic Benefits of Mechanical Insufflation-Exsufflation in Children With Neuromuscular Diseases

To analyze the physiologic effects and tolerance of mechanical insufflation-exsufflation (MI-E) by means of mechanical cough assistance (Cough Assist; JH Emerson Company; Cambridge, MA) for children with neuromuscular disease. Prospective clinical trial. Physiology laboratory of a pediatric pulmonary department of a university hospital. Seventeen children with Duchenne muscular dystrophy (n = 4), spinal muscular atrophy (n = 4), or other congenital myopathy (n = 9) who were in a stable state. Pressures of 15, 30, and 40 cm H(2)O were cycled to each patient, with 2 s for insufflation and 3 s for exsufflation. One application consisted of six cycles at each pressure for a total of three applications. Airway pressure and airflow were measured during every application. Breathing pattern, vital capacity (VC), sniff nasal inspiratory pressure (SNIP), peak expiratory flow (PEF), and respiratory comfort were evaluated at baseline and after each application. The tolerance of the patients was excellent, with a significant increase in the respiratory comfort score in all of the patients (p = 0.02). Expired volume during the MI-E application increased significantly to reach twice the VC at 40 cm H(2)O. Mean and maximal inspiratory and expiratory flows increased in a pressure-dependent manner. Breathing pattern did not change after the MI-E applications and pulse oximetric saturation remained stable within normal values, but the mean end-tidal carbon dioxide pressure decreased significantly. VC did not change, but the mean SNIP and PEF improved significantly after MI-E applications. Our results confirm the good tolerance and physiologic short-term benefit of the MI-E in children with neuromuscular disease who were in a stable state.

Comparison of Respiratory Physiologic Features When Infants Are Placed in Car Safety Seats or Car Beds

The objective of this study was to compare the respiratory physiologic features of healthy term infants placed in either a car bed or a car safety seat. Within the first 1 week of life, 67 healthy term infants were recruited and assigned randomly to be monitored in either a car bed (33 infants) or a car safety seat (34 infants). Physiologic data, including oxygen saturation and frequency and type of apnea, were obtained and analyzed in a blinded manner. The groups spent similar amounts of time in the devices (car bed: 71.6 minutes; car seat: 74.2 minutes). The mean oxygen saturation values were not different between the groups (car bed: 97.1%; car seat: 97.3%). The percentages of time with oxygen saturation of < 95% were also similar for the 2 groups (car bed: 11.8[corrected]%; car seat: 18.3[corrected]%). In both groups, a number of infants spent high percentages of study time with oxygen saturation of < 95%. The 6 infants with the most time at this level were all in the car safety seat group (54%-63% of study time). Values for the 6 infants in the car bed group with the most time at this level were lower (20%-42%). This difference in the duration of oxygen saturation of < 95% was not statistically significant. The mean end-tidal carbon dioxide levels and the numbers of episodes of apnea were similar for the 2 groups. The respiratory physiologic features of infants in the 2 car safety devices were observed to be similar. Of note, substantial periods of time with oxygen saturation of < 95% were surprisingly common in both groups.

End-Tidal Carbon Dioxide as a Measure of Acidosis Among Children With Gastroenteritis

We aimed to determine the correlation between end-tidal carbon dioxide levels and serum bicarbonate concentrations among patients with gastroenteritis, to compare the end-tidal carbon dioxide with other clinical parameters that might also be associated with the degree of acidosis, and to examine the relationship between end-tidal carbon dioxide levels and return visits. Our prospective sample included patients presenting to the emergency department with a chief complaint of vomiting and/or diarrhea. The association between end-tidal carbon dioxides and serum bicarbonate concentrations was determined with simple linear-regression analysis. Receiver operating characteristic curves were computed to determine the predictive ability of the end-tidal carbon dioxide to detect metabolic acidosis. One hundred thirty of 146 subjects who were approached were included in the final analysis. For those for whom laboratory studies were performed, the mean serum bicarbonate concentration was 17.3 +/- 4.3 mmol/L and the mean end-tidal carbon dioxide level was 34.2 +/- 5.2 mm Hg. End-tidal carbon dioxide levels and serum bicarbonate concentrations were correlated linearly in bivariate analysis. Receiver operating characteristic curves were calculated for end-tidal carbon dioxide as a predictor of serum bicarbonate concentrations of < or = 13, < or = 15, and < or = 17 mmol/L, with areas under the curves of 0.94, 0.95, and 0.90, respectively. The relationship between end-tidal carbon dioxide levels and serum bicarbonate concentrations was independent of other potential predictors of acidosis in multivariable analysis. The mean end-tidal carbon dioxide level for patients who required an unanticipated return visit (33.0 +/- 4.0 mm Hg) was lower than the level for those who did not seek reevaluation (36.6 +/- 3.6 mm Hg). End-tidal carbon dioxide levels were correlated with serum bicarbonate concentrations among children with vomiting and diarrhea, independent of other clinical parameters. Capnography offers an objective noninvasive measure of the severity of acidosis among patients with gastroenteritis.

Absence of Biochemical Evidence for Renal and Hepatic Dysfunction After 8 Hours of 1.25 Minimum Alveolar Concentration Sevoflurane Anesthesia in Volunteers

Background Sevoflurane is degraded by carbon dioxide absorbents to a difluorovinyl ether (compound A) that can cause renal and hepatic injury in rats. The present study applied sensitive markers of renal and hepatic function to determine the safety of prolonged (8 h), high concentration (3% end-tidal) sevoflurane anesthesia in human volunteers. Methods Thirteen healthy male volunteers provided informed consent to undergo 8 h of 1.25 minimum alveolar concentration sevoflurane anesthesia delivered with a fresh gas flow of 2 l/min. Glucose, protein, albumin, N-acetyl-beta-D-glucosaminidase (NAG), and alpha- and pi-glutathione-S-transferase (GST) levels were analyzed in urine collected at 24 h before and for 3 days after sevoflurane anesthesia. Daily blood samples were analyzed for creatinine, blood urea nitrogen (BUN), alanine aminotransferase, alkaline phosphatase, and bilirubin concentrations. Circuit compound A and plasma fluoride concentrations were measured. Results During anesthesia, average and maximum inspired compound A concentrations were 27 +/- 7 and 34 +/- 7 6 (mean +/- SD) and median mean blood pressure, esophageal temperature, and end-tidal carbon dioxide levels were 63 mmHg, 36.8 [degree sign] Celsius, and 32 mmHg, respectively. The average serum inorganic fluoride concentration 2 h after anesthesia was 66.2 +/- 14.7 micro Meter. Results of tests of hepatic function and renal function (BUN, creatinine concentration) were unchanged after anesthesia. Glucose, protein, albumin, and NAG excretion were not significantly increased after anesthesia. Urine concentrations of alpha-GST and pi-GST were increased on day 1 after anesthesia and alpha-GST was increased on day 2 after anesthesia but returned to normal afterward. Conclusions Prolonged (8 h), high concentration (3%) sevoflurane anesthesia administered to volunteers in a fresh gas flow of 2 l/min does not result in clinically significant changes in biochemical markers of renal or hepatic dysfunction.