ET CO2 Research Articles

Prevalence of Sleep Disordered Breathing in Adult Sickle Cell Clinic Patients and Cardiovascular Correlates

Sleep disordered breathing (SDB) is strongly correlated with hypertension and cardiovascular disease in the general population, and especially in African Americans. In Sickle Cell Disease (SCD), the adverse effect of nocturnal hypoxemia is anticipated to have additional adverse effects with the sickling of red blood cells and microvascular thrombosis unique to the disease. Prospective data regarding the prevalence and consequences of SDB in this population are lacking. In an ongoing study, 27 adult subjects (age > 18 years), with homozygous HbSS genotype, presenting to the Howard University Sickle Cell Center for routine follow up have been recruited irrespective of the presence of sleep symptoms. Exclusion criteria include previous diagnosis or treatment of a sleep disorder or requirement for supplemental oxygen. Testing occurs when subjects are in a stable phase of disease, with no hospitalizations or medication changes for 4 weeks. In addition to clinical history and questionnaires, participants are assessed with blood work, 6 minute walk testing, pain and sleep diaries during 1 week actigraphy, transthoracic echocardiography and overnight in lab polysomnography with capnography. At the time of this interim analysis, the mean age is 42 (range 29-71, +/- std dev 11) and male:female distribution is 17:10. The mean BMI is 20.4 (+/- 4.5). Mean Hgb is 9.1 g/dl (+/- 1.8) and mean LDH is 325 iu/L (+/- 163). Polysomnography scoring utilized a 3% desaturation criterion for hyponeas as per American Academy of Sleep Medicine Scoring Manual Chapter VIII, 1A. Mean sleep efficiency is 77% ( std dev +/- 4.2%). 48% of subjects demonstrate some degree of sleep disordered breathing as defined by an AHI > 5 events/hour (33% mild, 4% moderate, 11% severe). 70% of subjects demonstrate an RDI > 5 events/hour (40% mild, 19% moderate, 11% severe). Twelve participants (44%) exhibit more than 5 minutes sleep duration at saturations <89% (mean = 187 minutes). Hypercapnia is not suggested as an important component of SDB with the mean ET CO2 = 40.7 mm Hg (range 30-46 mm Hg). Echocardiographic values (LVPWd, Lad, MV E/A, PVV, and RVSP) do not correlate with any indices of sleep disordered breathing other than minutes <89% saturation correlating with RVSP. In summary, this interim analysis of sleep in a population of unselected Sickle Cell Clinic patients demonstrates a striking frequency of sleep disordered breathing. This is despite a generally low BMI for these patients which is typically considered one of the most important risk factor for sleep apnea. Ongoing recruitment is planned to confirm these findings. Correlation with clinical outcomes and potential response to therapeutic interventions will be important future research questions.

Effect of end-tidal carbon dioxide level on the optic nerve sheath diameter measured by transorbital ultrasonography in anesthetized pediatric patients: A randomized trial.

Intraoperative hypercapnia and hypocapnia are common during pediatric anesthesia, and the cerebral blood flow and intracranial pressure may be affected by the partial pressure of arterial carbon dioxide. Transorbital ultrasound measurement of the optic nerve sheath diameter is a simple and non-invasive method for intracranial pressure assessment. The objective of this study was to evaluate the effect of end-tidal carbon dioxide (ET CO2 ) on optic nerve sheath diameter in a healthy anesthetized pediatric population. Pediatric patients scheduled for elective surgery under general anesthesia and mechanical ventilation in the supine position were enrolled and divided into four subgroups; age<2years, 2-6years, 6-12years, and 12-18years. Mechanical ventilation was adjusted to achieve target ET CO2 levels in a randomized sequence (40-35-45-40mmHg or 40-45-35-40mmHg). Three minutes after reaching each target ET CO2 level, transorbital ultrasound images of optic nerve sheath diameter were obtained and analyzed. The primary outcome was the optic nerve sheath diameter at each ET CO2 level. Sixty-four pediatric patients were enrolled and analyzed. At ET CO2 =40mmHg, the optic nerve sheath diameter was 5.6±0.6mm, 6.4±0.5mm, 6.8±0.6mm, and 7.1±0.5mm in children aged <2years, 2-6years, 6-12years, and 12-18years, respectively. The overall percent decreases in the optic nerve sheath diameter was -5.6±-4.3% (95% CI; -6.7 to -4.5%) at ET CO2 =35mmHg while the overall percent increases of optic nerve sheath diameter (ONSD) was 4.9±5.1% (95% CI; 3.6 to 6.1%) at ET CO2 =45mmHg compared with those at ET CO2 =40mmHg. Spearman rank correlation analysis indicated that there were weak to moderate correlation between ET CO2 and the optic nerve sheath diameter (correlation coefficient [p-value]=.355 [.004], .318 [.014], .373 [<.001], and .420 [<.001] in children aged <2years, 2-6years, 6-12years, and 12-18years, respectively). The optic nerve sheath diameter measured by transorbital ultrasound showed rapid reactivity from ET CO2 35 to 45mmHg in healthy pediatric patients under inhalation general anesthesia.

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia

Comparison of the Safety and Efficacy of Valveless and Standard Insufflation During Robotic Partial Nephrectomy: A Prospective, Randomized, Multi-institutional Trial

ObjectiveTo use a randomized, prospective, multi-institutional study to compare the safety and efficacy of conventional insufflation (CIS) and valveless insufflation (AirSeal Insufflation – AIS) at the conventional pressure of 15 mm Hg in robot-assisted partial nephrectomy – a surgery where AIS has gained popularity for maintaining visualization despite suction. This study was also powered to evaluate the effect of decreasing pneumoperitoneum by 20% in the valveless system. Materials and MethodsThree high-volume institutions randomized subjects into CIS 15, AIS 15, and AIS 12 mm Hg cohorts. Endpoints included rates of subcutaneous emphysema (SCE), pneumothorax (PTX), pneumomediastinum (PMS), intraoperative end-tidal carbon dioxide (ET CO2), and peak airway pressure (PAP), as well as hospital stay, post-operative pain, and complications. Given the substantial proportion of retroperitoneal surgery, a secondary analysis evaluated the effect of surgical approach. ResultsTwo hundred and two patients were accrued. SCE was decreased in the AIS 12 mm Hg group (p=0.003). PTX and PMS rates were not statistically significantly different across the 3 insufflation groups. Higher rates of SCE and PMS, although not PTX, were noted in all retroperitoneal surgery groups – with lower SCE rates for AIS 12 mm Hg regardless of surgical approach. ConclusionAIS is often preferred for complex procedures including retroperitoneal and transperitoneal robotic-assisted partial nephrectomy, for its maintenance of pneumoperitoneum despite continuous suction necessary for visualization. This study shows that AIS is safe when compared to CIS at 15 mm Hg, and shows improvement in outcomes when pneumoperitoneum pressure is reduced by 20% to 12 mmHg.

Biometric Analysis of Surgeons' Physiologic Responses During Surgery.

Much has been written from the social science perspective surrounding surgeons' stress and burn out. The literature is sparse in reference to scientific investigations of the hemodynamic effect of that stress. This prospective clinical study quantifies the physiologic impact of performing surgery upon the acute care surgeon. Over 2.5 years, monitoring devices were affixed to surgeons prior to entering the operating room, and physiologic variables were documented every 30 minutes. Qualifying cases were projected as being greater than 2 hours with a baseline preoperative measurement obtained. Variables recorded included blood pressure (BP), heart rate (HR), rate pressure product (RPP), oxygen saturation (O2 sat), and end-tidal carbon dioxide (ET CO2). Statistically significant differences (P < .05) were found between baseline data to the maximum recording during the surgical operation for: BP (min 101 ± 6.6 (mmHg)-max 117 ± 5.1 (mmHg)), HR (min 70.5 ± 6.2 (bpm)-max 83.7 ± 9.0 (bpm)), O2 sat (min 97 ± 2.0 (%)-max 100 ± 0.22(%)), and ET CO2 (min 34.1 ± 1.15 mmHg-max 38 ± 1.7 mmHg) (P < .0001). The RPP ranged from 10.49 mmHg/min to 15.88 mmHg/min with a mean of 14.00 mmHg/min. The practice of surgery is considered demanding in training and lifestyle in comparison to other medical specialties. This data is among the first to demonstrate the negative physiological impact of surgery upon the metabolic demand of the surgeon. The longitudinal implications of increased physiologic demand over time may have cardiovascular and cerebrovascular consequences.

Comparative Study Between Total Intravenous Anesthesia Versus Volatile Induction and Maintenance Anesthesia with Sevoflurane for Bariatric Operations

Background: Morbid obesity is defined as a body weight 160% above the ideal weight for survival or 40 kg/m2 or >35 with serious comorbidity. Long-term surveys revealed that surgical intervention has been the only method to effectively sustain weight loss in these patients. Objectives: To compare total intravenous anesthesia applied with propofol-fentanyl to sevoflurane single breath and maintenance anesthesia. Patients and Methods: This prospective randomized clinical study was approved by the ethics committee in AlAzhar University and a written informed patient's consent was obtained. This study included 50 patients of both sexes, admitted for bariatric surgery carried out at Al-Azhar University Hospitals (El-Hussein and Bab El-Sharia). They were randomly allocated into two equal groups, TIVA group: 25 patients will receive total intravenous anesthesia applied with propofol-fentanyl. Group VIMA: sevoflurane single breath induction and maintenance group: 25 patients will receive - sevoflurane single breath induction and maintenance. Results: Total intravenous anesthesia using (fentanyl and propofol). Volatile induction and maintenance anesthesia (Inhalational anesthesia) using (fentanyl and sevoflurane). The following parameters were assessed between the 2 groups: Hemodynamics, SPo2 and ET Co2 were continuously monitored and recorded at 15 min interval. Conclusion: This study showed that both TIVA and VIMA were effective in bariatric surgeries. Regarding neuroendocrine stress response, TIVA group was provided suppressed hormone levels suggesting that there was suppression of stress response unlike VIMA group that showed even raised serum levels of those hormones.

Total intravenous anaesthesia versus volatile induction and maintenance anaesthesia for controlled hypotension in lumbar spine fixation surgery: Comparative clinical study

Background: Controlled hypotension during general anesthesia aims to lower the mean arterial blood pressure (MAP)to values between 55 and 65 mmHg in patients with normal blood pressure, with the goal of significantly reducing blood loss by maintaining it at this level throughout the operation process. Controlled hypotension is frequently used for obtaining better exposure during spine surgery as small bleeding areas can produce better surgical field visibility and result in decreased time of surgery.Objective: This study was done to compare the efficacy and safety of TIVA and VIMA to induce hypotensive technique during spine surgery, with attention on the amount of blood loss, blood transfusion, hemodynamics, time of recovery and postoperative nausea and vomiting. Patients and Methods: This study included 40 patients of both sex, admitted for lumbar spine fixation surgery carried out at Al- Azhar University Hospitals (El-Hussein and Bab El-Sharia). They were randomly allocated into two equal groups, 20 patients each (n= 20): Group I (TIVA); Total intravenous anaesthesia using (fentanyl and propofol). Group II (VIMA); Volatile induction and maintenance anesthesia (Inhalational anaesthesia) using (fentanyl and sevoflurane). Results: The following parameters were assessed between the 2 groups: Hemodynamics (HR, SBP, DBP and MAP), SPO2 and ET CO2 were continuously monitored and recorded at 15 min interval. Intraoperative blood loss, blood transfusion, duration of surgery, time of recovery and postoperative nausea and vomiting were monitored in all patients. Conclusion: this study showed that both TIVA and VIMA were effective in producing controlled hypotension for lumbar spinal fixation surgery. However, only TIVA was beneficial, allowing properly controlled hypotension, minimized intraoperative bleeding, and improved surgical field visibility compared to VIMA.

Total intravenous anaesthesia versus volatile induction and maintenance anaesthesia for controlled hypotension in lumbar spine fixation surgery: Comparative clinical study

Background: Controlled hypotension during general anesthesia aims to lower the mean arterial blood pressure (MAP)to values between 55 and 65 mmHg in patients with normal blood pressure, with the goal of significantly reducing blood loss by maintaining it at this level throughout the operation process. Controlled hypotension is frequently used for obtaining better exposure during spine surgery as small bleeding areas can produce better surgical field visibility and result in decreased time of surgery.Objective: This study was done to compare the efficacy and safety of TIVA and VIMA to induce hypotensive technique during spine surgery, with attention on the amount of blood loss, blood transfusion, hemodynamics, time of recovery and postoperative nausea and vomiting. Patients and Methods: This study included 40 patients of both sex, admitted for lumbar spine fixation surgery carried out at Al- Azhar University Hospitals (El-Hussein and Bab El-Sharia). They were randomly allocated into two equal groups, 20 patients each (n= 20): Group I (TIVA); Total intravenous anaesthesia using (fentanyl and propofol). Group II (VIMA); Volatile induction and maintenance anesthesia (Inhalational anaesthesia) using (fentanyl and sevoflurane). Results: The following parameters were assessed between the 2 groups: Hemodynamics (HR, SBP, DBP and MAP), SPO2 and ET CO2 were continuously monitored and recorded at 15 min interval. Intraoperative blood loss, blood transfusion, duration of surgery, time of recovery and postoperative nausea and vomiting were monitored in all patients. Conclusion: this study showed that both TIVA and VIMA were effective in producing controlled hypotension for lumbar spinal fixation surgery. However, only TIVA was beneficial, allowing properly controlled hypotension, minimized intraoperative bleeding, and improved surgical field visibility compared to VIMA.

Flexion decreases the ventilation quality of the Ambu® AuraGain™ laryngeal mask in paralysed children: A prospective randomised crossover study.

The influence of different head and neck positions on ventilation with the Ambu® AuraGain™ remains unevaluated in children. This study assessed the influence of different head and neck positions on ventilation with the AuraGain™ in paediatric patients. In this prospective, randomised crossover study, children ≤7years of age who were scheduled for elective surgery under general anaesthesia were enrolled. An AuraGain™ was placed in all patients; mechanical ventilation was performed using a volume-controlled mode with a tidal volume of 10mL/kg. Respiratory rate was adjusted to maintain a ETCO2 of 35-40mmHg. The oropharyngeal leak pressure, expiratory tidal volume, peak inspiratory pressure, ventilation score and fibreoptic bronchoscopic view score were assessed for the neutral head and neck position, and then for the flexed, extended and rotated head and neck positions in a random order. Compared with the neutral position, the oropharyngeal leak pressure increased in the flexed position (P<.001), and decreased in the extended (P=.014) and rotated position (P=.002). The expiratory tidal volume and ventilation score were significantly reduced during flexion (all P<.005), and were comparable among the neutral, extended and rotated positions. The fibreoptic score improved in the extended and rotated position (all P<.001). Only the flexion ventilation score was lower compared with the neutral position (P=.014). Clinically, the flexed head and neck positions negatively affected ventilation due to obstruction of the airway. Ventilation with AuraGain™ can be effectively performed with the head and neck in the neutral, extended and rotated position in paediatric patients.

Development of an anaesthetized-rat model of exercise hyperpnoea: an integrative model of respiratory control using an equilibrium diagram.

New Findings What is the central question of this study? The lack of useful small‐animal models for studying exercise hyperpnoea makes it difficult to investigate the underlying mechanisms of exercise‐induced ventilatory abnormalities in various disease states. What is the main finding and its importance? We developed an anaesthetized‐rat model for studying exercise hyperpnoea, using a respiratory equilibrium diagram for quantitative characterization of the respiratory chemoreflex feedback system. This experimental model will provide an opportunity to clarify the major determinant mechanisms of exercise hyperpnoea, and will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models. Exercise‐induced ventilatory abnormalities in various disease states seem to arise from pathological changes of respiratory regulation. Although experimental studies in small animals are essential to investigate the pathophysiological basis of various disease models, the lack of an integrated framework for quantitatively characterizing respiratory regulation during exercise prevents us from resolving these problems. The purpose of this study was to develop an anaesthetized‐rat model for studying exercise hyperpnoea for quantitative characterization of the respiratory chemoreflex feedback system. In 24 anaesthetized rats, we induced muscle contraction by stimulating bilateral distal sciatic nerves at low and high voltage to mimic exercise. We recorded breath‐by‐breath respiratory gas analysis data and cardiorespiratory responses while running two protocols to characterize the controller and plant of the respiratory chemoreflex. The controller was characterized by determining the linear relationship between end‐tidal CO2 pressure (P ETC O2) and minute ventilation (V˙E), and the plant by the hyperbolic relationship between V˙E and P ETC O2. During exercise, the controller curve shifted upward without change in controller gain, accompanying increased oxygen uptake. The hyperbolic plant curve shifted rightward and downward depending on exercise intensity as predicted by increased metabolism. Exercise intensity‐dependent changes in operating points (V˙E and P ETC O2) were estimated by integrating the controller and plant curves in a respiratory equilibrium diagram. In conclusion, we developed an anaesthetized‐rat model for studying exercise hyperpnoea, using systems analysis for quantitative characterization of the respiratory system. This novel experimental model will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models.

End-tidal CO2 on admission is associated with hemorrhagic shock and predicts the need for massive transfusion as defined by the critical administration threshold: A pilot study

BackgroundCritical administration threshold (≥3 units of packed red blood cells/h or CAT+) has been proposed as a new definition for massive transfusion (MT) that includes volume and rate of blood transfusion. CAT+ has been shown to eliminate survivor bias and be a better predictor of mortality than the traditional MT (>10 units/24h). End-tidal CO2 (ET CO2) negatively correlates with lactate and is an early predictor of shock in trauma patients. We conducted a pilot study to test the hypothesis that low ET CO2 on admission predicts CAT+. MethodsET CO2 via capnography and serum lactate were prospectively collected on admission for 131 patients requiring trauma team activation. Demographic data were obtained from patient charts. Excluded were patients with isolated head injuries, traumatic arrests, or pre-hospital intubations. CAT± status was determined for each hour up to 6h from admission as described; likewise, MT± status was determined up to 24h from admission. ResultsAfter exclusion criteria, 67 patients were analyzed. Mean age was 41.2 (SD 18.5). Thirty-three patients had a blunt mechanism of injury (49%), median ISS was 9 (interquartile range 4–19), and there were 6 deaths (9%). ET CO2 and lactate were negatively correlated by Spearman rank-based correlation (rho=−0.41, p=0.0006). Twenty-one (31%) and 8 (12%) patients were CAT+ and traditional MT+, respectively. There were a significantly greater proportion of patients with ISS>15, ET CO2 <35, or who died found to be CAT+. A binomial logistic regression model adjusting for age, SBP <90, HR, and ISS >15 revealed ET CO2 < 35 to be independently predictive of CAT+ (OR 9.24, 95% CI 1.51-56.57, p=0.016). ConclusionsThis pilot study demonstrated that low ET CO2 had strong association with standard indicators for shock and was predictive of patients meeting CAT+ criteria in the first 6h after admission. Further study to verify these results and to elucidate CAT criteria’s association with mortality will require a larger sample size.

Carbon dioxide-mediated vasomotion of extra-cranial cerebral arteries in humans: a role for prostaglandins?

Cerebral blood flow increases during hypercapnia and decreases during hypocapnia; it is unknown if vasomotion of the internal carotid artery is implicated in these responses. Indomethacin, a non-selective cyclooxygenase inhibitor (used to inhibit prostaglandin synthesis), has a unique ability to blunt cerebrovascular carbon dioxide reactivity, while other cyclooxygenase inhibitors have no effect. We show significant dilatation and constriction of the internal carotid artery during hypercapnia and hypocapnia, respectively. Indomethacin, but not ketorolac or naproxen, reduced the dilatatory response of the internal carotid artery to hypercapnia The differential effect of indomethacin compared to ketorolac and naproxen suggests that indomethacin inhibits vasomotion of the internal carotid artery independent of prostaglandin synthesis inhibition. Extra-cranial cerebral blood vessels are implicated in the regulation of cerebral blood flow during changes in arterial CO2 ; however, the mechanisms governing CO2 -mediated vasomotion of these vessels in humans remain unclear. We determined if cyclooxygenase inhibition with indomethacin (INDO) reduces the vasomotor response of the internal carotid artery (ICA) to changes in end-tidal CO2 (P ETC O2). Using a randomized single-blinded placebo-controlled study, participants (n=10) were tested on two occasions, before and 90min following oral INDO (1.2mgkg(-1) ) or placebo. Concurrent measurements of beat-by-beat velocity, diameter and blood flow of the ICA were made at rest and during steady-state stages (4min) of iso-oxic hypercapnia (+3, +6, +9mmHg P ETC O2) and hypocapnia (-3, -6, -9mmHg P ETC O2). To examine if INDO affects ICA vasomotion independent of cyclooxygenase inhibition, two participant subsets (each n=5) were tested before and following oral ketorolac (post 45min, 0.25mgkg(-1) ) or naproxen (post 90min, 4.2mgkg(-1) ). During pre-drug testing in the INDO trial, the ICA dilatated during hypercapnia at +6mmHg (4.72±0.45 vs. 4.95±0.51mm; P<0.001) and +9mmHg (4.72±0.45mm vs. 5.12±0.47mm; P<0.001), and constricted during hypocapnia at -6mmHg (4.95±0.33 vs. 4.88±0.27mm; P<0.05) and -9mmHg (4.95±0.33 vs. 4.82±0.27mm; P<0.001). Following INDO, vasomotor responsiveness of the ICA to hypercapnia was reduced by 67±28% (0.045±0.015 vs. 0.015±0.012mmmmHg P ETC O2(-1) ). There was no effect of the drug in the ketorolac and naproxen trials. We conclude that: (1) INDO markedly reduces the vasomotor response of the ICA to changes in P ETC O2; and (2) INDO may be reducing CO2 -mediated vasomotion via a mechanism(s) independent of cyclooxygenase inhibition.

Corticospinal excitability is associated with hypocapnia but not changes in cerebral blood flow.

Reductions in cerebral blood flow (CBF) may be implicated in the development of neuromuscular fatigue; however, the contribution from hypocapnic-induced reductions (i.e. P ETC O2) in CBF versus reductions in CBF per se has yet to be isolated. We assessed neuromuscular function while using indomethacin to selectively reduce CBF without changes in P ETC O2 and controlled hyperventilation-induced hypocapnia to reduce both CBF and P ETC O2. Increased corticospinal excitability appears to be exclusive to reductions in P ETC O2 but not reductions in CBF, whereas sub-optimal voluntary output from the motor cortex is moderately associated with decreased CBF independent of changes in P ETC O2. These findings suggest that changes in CBF and P ETC O2 have distinct roles in modulating neuromuscular function. Although reductions in cerebral blood flow (CBF) may be involved in central fatigue, the contribution from hypocapnia-induced reductions in CBF versus reductions in CBF per se has not been isolated. This study examined whether reduced arterial PCO2 (P aC O2), independent of concomitant reductions in CBF, impairs neuromuscular function. Neuromuscular function, as indicated by motor-evoked potentials (MEPs), maximal M-wave (Mmax ) and cortical voluntary activation (cVA) of the flexor carpi radialis muscle during isometric wrist flexion, was assessed in ten males (29±10years) during three separate conditions: (1) cyclooxygenase inhibition using indomethacin (Indomethacin, 1.2mgkg(-1) ) to selectively reduce CBF by 28.8±10.3% (estimated using transcranial Doppler ultrasound) without changes in end-tidal PCO2 (P ETC O2); (2) controlled iso-oxic hyperventilation-induced reductions in P aC O2 (Hypocapnia), P ETC O2 =30.1±4.5mmHg with related reductions in CBF (21.7±6.3%); and (3) isocapnic hyperventilation (Isocapnia) to examine the potential direct influence of hyperventilation-mediated activation of respiratory control centres on CBF and changes in neuromuscular function. Change in MEP amplitude (%Mmax ) from baseline was greater in Hypocapnia tha in Isocapnia (11.7±9.8%, 95% confidence interval (CI) [2.6, 20.7], P=0.01) and Indomethacin (13.3±11.3%, 95% CI [2.8, 23.7], P=0.01) with a large Cohen's effect size (d ≥ 1.17). Although not statistically significant, cVA was reduced with a moderate effect size in Indomethacin (d=0.7) and Hypocapnia (d=0.9) compared to Isocapnia. In summary, increased corticospinal excitability - as reflected by larger MEP amplitude - appears to be exclusive to reduced P aC O2, but not reductions in CBF per se. Sub-optimal voluntary output from the motor cortex is moderately associated with decreased CBF, independent of reduced P aC O2.

Evaluation the effect of breathing filters on end-tidal carbon dioxide during inferior abdominal surgery in infants and changes of tidal volume and respiratory rate needs for preventing of increasing end-tidal carbon dioxide.

Background:The aim of this study was to prevent of increasing end-tidal carbon dioxide (ETCO2) with changing of vital capacity and respiratory rate when using of birthing filter in infants.Materials and Methods:In a randomized clinical trial study, ninety-four infant’ patients were studied in three groups. Basic values, such as peak inspiratory pressure, tidal volume, minute ventilation, respiratory rate, and partial pressure of ET CO2 (PETCO2) level had been evaluated after intubation, 10 min after intubation and 10 min after filter insertion. In the first group, patients only observed for changing in ETCO2 level. In the second and the third groups, respiratory rates and tidal volume had been increased retrospectively, until that ETCO2 ≤35 mmHg was received. We used ANOVA, Chi-square, and descriptive tests for data analysis. P < 0.05 was considered statistically significant.Results:Tidal volume 10 min after filter insertion was statistically higher in Group 3 (145.0 ± 26.3 ml) versus 129.3 ± 38.9 ml in Group 1 and 118.7 ± 20.8 ml in Group 2 (P = 0.02). Furthermore, respiratory rate at this time was statistically higher in Group 2 (25.82 ± 0.43) versus Groups 1 and 3 (21.05 ± 0.20 ml and 21.02 ± 0.60 ml, respectively) (P = 0.001). Minute volume and PETCO2 level were statistically significant between Group 1 and the other two groups after filter insertion (P = 0.01 and P = 0.00,1 respectively).Conclusion:With changing the vital capacity and respiratory rate we can control PETCO2 level ≤35 mmHg during using of birthing filters in infants. We recommend this instrument during anesthesia of infants.

Effect of Intravenous Administration of Tramadol on the Minimum Alveolar Concentration of Isoflurane in Dogs

This study was aimed to evaluate the effects of tramadol hydrochloride on the minimum alveolar concentration of isoflurane (MAC ISO ) in dogs. Six healthy, female German shepherd dogs (aged 1-2 years) were used in this study. Anesthesia was induced by mask induction and maintained with isoflurane in oxygen. Mechanical ventilation maintained the end-tidal CO₂ partial pressure (P ET CO₂) from 35 to 45 mmHg throughout the study. A baseline MAC ISO (MAC ISO B) was determined starting 45 minutes after induction of anesthesia by clamping a pedal digit until gross purposeful movement was detected. After MAC ISO B determination, dogs received a tramadol loading dose of 3 mg/kg followed by a continuous rate infusion (CRI) of 2.6 mg/kg/h. The determination of MAC ISO after administration of tramadol (MAC ISO T) began 20 min after the start of the CRI. Arterial blood pressure and heart rate were recorded continuously and arterial blood samples for blood gas analysis were collected at the end of the equilibration period. Mean ± SD values for the MAC ISO B and MAC ISO T were 1.33 ± 0.04% and 1.23 ± 0.04%, respectively. The MAC ISO B decreased significantly by 7.5 ± 0.2% (P ISO without depression of cardiorespiratory function. Thus, the use of tramadol on inhalation anesthesia with isoflurane in dogs can improve the stability of anesthesia and the quality of recovery.

Sa1468 Differentiation of Patients With Acute Gastrointestinal Bleeding From Those With Occult Bleeding by End-Tidal Carbon Dioxide Levels: a Pilot Study

Recent studies have shown that end tidal carbon dioxide (ET CO2) levels have an inverse correlation with serum lactate levels in trauma patients and may be an earlier indicator of the switch from aerobic to anaerobic metabolism as a result of hypoperfusion to vital organs secondary to hemorrhagic shock. Those studies also suggest that ET CO2 levels (< 35 mm Hg) were associated with acute blood loss and the need for operative intervention. We hypothesize that patients with a significant acute GI bleed may also show lower ET CO2 readings by a similar mechanism in comparison to those with occult GI blood loss, suggesting its value as a prognostic marker in assessing patients with emergency department (ED) presentations of this condition.

Carbon dioxide monitoring during laparoscopic-assisted bariatric surgery in severely obese patients: transcutaneous versus end-tidal techniques.

Various factors including severe obesity or increases in intra-abdominal pressure during laparoscopy can lead to inaccuracies in end-tidal carbon dioxide (PETCO2) monitoring. The current study prospectively compares ET and transcutaneous (TC) CO2 monitoring in severely obese adolescents and young adults during laparoscopic-assisted bariatric surgery. Carbon dioxide was measured with both ET and TC devices during insufflation and laparoscopic bariatric surgery. The differences between each measure (PETCO2 and TC-CO2) and the PaCO2 were compared using a non-paired t test, Fisher's exact test, and a Bland-Altman analysis. The study cohort included 25 adolescents with a mean body mass index of 50.2 kg/m2 undergoing laparoscopic bariatric surgery. There was no difference in the absolute difference between the TC-CO2 and PaCO2 (3.2±3.0 mmHg) and the absolute difference between the PETCO2 and PaCO2 (3.7±2.5 mmHg). The bias and precision were 0.3 and 4.3 mmHg for TC monitoring versus PaCO2 and 3.2 and 3.2 mmHg for ET monitoring versus PaCO2. In the young severely obese population both TC and PETCO2 monitoring can be used to effectively estimate PaCO2. The correlation of PaCO2 to TC-CO2 is good, and similar to the correlation of PaCO2 to PETCO2. In this population, both of these non-invasive measures of PaCO2 can be used to monitor ventilation and minimize arterial blood gas sampling.

Recovery from general anaesthesia in the elderly patient: sevoflurane vs propofol

Materials and methods This study compares recovery times from general anaesthesia between the selected drugs in patients over 65yo who underwent surgery. In 3 months 41 patients were selected, similar in age (65-78yo), sex and ASA class, undergoing elective surgery. Patients with lung, liver, kidney, brain and coronaric dysfunctions with ASA III-IV were excluded from the study. In this single-blind, prospectic study patients were randomized in 2 groups: patients in P-group were treated with propofol (5-8 mg/kg/h), while patients in Sgroup were treated with sevoflurane (1-2%). Dosage was managed so that CF and AP wouldn’t shift more than 20% their basal values. All patients were pre-treated with midazolam (0.03mg/kg), fentanyl (1μg/ kg) and atropine (up to 0.01ng/kg). Anaesthesia was induced using propofol (2mg/kg) and cisatracurium (0.2mg/kg). Patients were intubated and ventilated using O2 (33%) and N2O (66%). Analgesia during surgery was achieved using fentanyl (1μg/kg) 60min after induction and then using boli every 45min. Parameters monitored for each patient were: AP, CF, ECG, PO2, ET CO2, BIS and diuresis. Times for extubation, recovery room monitoring, eye opening and oriented motory and verbal response were recorded. MMSE was also taken.

The use of emergency medical cooling system pads in the treatment of malignant hyperthermia

Editor, Malignant hyperthermia is an inherited and potentially lethal hypermetabolic syndrome triggered by halogenated volatile inhalational agents and/or depolarizing muscle relaxants. Because malignant hyperthermia is always associated with general anaesthesia, the syndrome is theoretically well known among anaesthesiologists. However, due to its rarity, clinical experience is limited. Early diagnosis and prompt but appropriate intervention are essential to reduce morbidity and mortality.

Therapeutic hypothermia: surgical infant with neonatal encephalopathy

Seventy-two hours of therapeutic hypothermia (HT) with a core temperature of 33.5–34.5 C commenced within 6 h of life is becoming the standard of care aiming to reduce death ⁄disability after neonatal encephalopathy (NE) (1–3). As a result of concerns about maintaining haemodynamic stability and normal clotting during surgery, and post-operative wound healing (4), infants with NE born with major congenital abnormalities requiring surgery were excluded in the HT trials. In the UK, infants undergoing HT since the end of total body hypothermia (TOBY) trial are registered into the TOBY registry and managed using a standardized protocol (5). There is no previous report of undertaking surgery in an encephalopathic infant during therapeutic HT. We report our first infant with NE and oesophageal atresia and tracheoesophageal fistula (TEF) who underwent surgery while undergoing therapeutic HT. A 29-year old gravida three para one mother with adequately controlled diabetes mellitus and asthma, noted to have polyhydramnios and foetal unilateral severe hydronephrosis and possible TEF in antenatal scans, delivered a male baby at 39 + 3 weeks gestation, weighing 3340 g by emergency caesarean section following foetal distress, poor cardiotocograph (CTG) trace and ante partum haemorrhage. He needed resuscitation and satisfied the NE inclusion criteria for HT [cord pH: 6.92, base deficit: 16 mmol ⁄L, ventilated, hypotonic and encephalopathic and moderately abnormal amplitude integrated electroencephalography (aEEG) (Fig. 1)]. He was then diagnosed with TEF needing imminent surgery, as well as a ventricular septal defect (VSD). As congenital malformation was a relative contraindication for HT, the benefits over risks were weighed with the surgical team, and HT was commenced after discussion with the parents. At 1.5 h, therapeutic HT was initiated using gloves filled with cold water placed around his head and body and external heating was turned off. At 3.5 h, the rectal temperature (Trec) was 34 C and the infant was transferred to surgery (Fig. 1). HT [Trec (33.1–34 C) (Fig. 1)] was then maintained by not actively warming (passive HT) until returning to neonatal intensive care unit (NICU) after 7 h of surgery. Anaesthesia was induced and maintained with isoflurane (0.86–0.97%), atracurium, fentanyl and morphine throughout the 3 h surgery. In our patient, the TEF was connected to the left main stem bronchus rather than the trachea, which is a rare presentation. This was however identified and divided, and an end to end oesophageal anastomosis was performed. There was minimal blood loss and no transfusion was given. During surgery, the mean (SD) end tidal CO2 (ET CO2) was: 4.2 (0.7) kPa and pCO2 was managed by pH stat [mean (SD):6.29 (1.42) kPa] (measured at 37 C), to maintain pCO2 in the normal range when corrected to Trec of 33.5 C (6).There were no arrhythmias. Heart rate, mean arterial blood pressure, oxygen requirement and Trec at HT were stable during surgery and post-surgery as shown in Fig. 1. He was ventilated and electively muscle relaxed with vecuronium for 5 days to protect the oesophageal anastomosis, which was under tension. On arrival back in the NICU, his Trec was 32.8 C. Active cooling was then continued for 72 h using a body wrap circulated with cold water servocontrolled to the Trec set at 33.5 C [Criticool; Medical ThermoRegulation Expertise (MTRE), Yavne, Israel]. Trec was stable at 33.5 ± 0.1 C Abbreviations aEEG, amplitude integrated electroencephalography; FFP, fresh frozen plasma; HT, Hypothermia; MRI, Magnetic resonance imaging; NE, Neonatal encephalopathy; NICU, neonatal intensive care unit; TEF, tracheoesophageal fistula; Trec, rectal temperature. Acta Paediatrica ISSN 0803–5253