Partial Oxygen Saturation Research Articles

Evaluation of the effect of two active warming and humidifying high-flow oxygen therapy systems in patients with tracheotomy.

The present study evaluated the effect of two active warming and humidifying high-flow oxygen therapy systems in patients with tracheotomy, in order to provide a basis for selecting the method of humidification oxygen therapy for tracheotomy. A total of 78 patients with tracheotomy, who underwent surgery between July 2017 and December 2017, were randomly divided into an observation group (39 patients) and a control group (39 patients). Patients in the observation group were treated with artificial airway high-flow humidification oxygen therapy in a closed suction system. Patients in the control group were treated using a respiratory humidification therapy device. Changes of sputum viscosity, pulmonary infection, arterial oxygen partial pressure (PaO2), arterial blood carbon dioxide partial pressure (PaCO2) and arterial oxygen saturation (SaO2) were observed at 0, 48 and 96 h, and 7 days following oxygen therapy. The sputum viscosity and lung infection in the observation group were lower than those in the control group at 48, 96 h and 7 days following oxygen therapy, and the PaO2 and SaO2 were higher in the observation group than in the control group, which was statistically significant (P<0.05). However, there was no statistically significant difference (P>0.05) in PaCO2 between the two groups. In conclusion, the artificial airway high-flow humidification oxygen therapy closed suction system was considered more suitable for long-term oxygen therapy of tracheotomy patients than the respiratory humidification therapy device. It can improve airway humidification and oxygen levels at lower equipment and consumable costs. The effects of treatment aim to reduce lung infections, which have clinical implications to a certain extent.

Histological, Ultrastructural, and Physiological Evaluation of a Rat Model of Obstructive Sleep Apnea Syndrome.

BackgroundPatients with obstructive sleep apnea syndrome (OSAS) are at an increased risk of cardiovascular disease. The aims of this study were to develop a rat model of OSAS and to validate the use of the model by investigating respiratory and cardiovascular physiological parameters and morphological changes by light microscopy and electron microscopy.Material/MethodsSixty 3-month-old Sprague-Dawley rats were assigned to the model group (n=30) and the control group (n=30). The rats in the OSAS model group were injected with 0.1 ml sodium hyaluronate solution into the upper respiratory tract at the junction between the hard and soft palate. After one month, the model and normal rats were compared using tests of respiratory and cardiac function, and histology and electron microscopy of the lung and cardiac tissue.ResultsIn the rat model of OSAS, airway obstruction resulted in the collapse of the upper airway. Tests of respiratory function showed that the oxygen partial pressure, oxygen concentration, and oxygen saturation in the model group were significantly lower when compared with the control group. In the model group, histology of the heart showed cardiac myocyte disarray, and electron microscopy showed vacuolar degeneration and mitochondrial abnormalities. The rat model of upper airway occlusion showed pulmonary and cardiac changes that have been described in OSAS.ConclusionsA rat model of upper airway occlusion resulted in physiological and morphological changes in the lung and heart due to hypoxia, and may be used for future studies on OSAS.

The neuroprotective effect of hyperoxygenate hydrogen-rich saline on CO-induced brain injury in rats

This study was designed to investigate the neuroprotective effect of hyperoxygenate hydrogen-rich saline (HOHS) against brain injury induced by carbon monoxide (CO) poisoning in rats. A rat model of CO poisoning was established by administering CO via intraperitoneal injection to male Sprague-Dawley rats. Forty-eight adult male rats were randomly divided into the following groups: normal control group (NG), CO poisoning group (CO), HOS treatment group (hyperoxygenated solution, HOS) and HOHS treatment group (HOHS). After CO poisoning, the carboxyhemoglobin (COHb) contents in the blood of rats in all the CO poisoning groups were increased significantly. However, HOS and HOHS significantly decreased COHb contents, furthermore, the HOHS group had lower COHb contents than the HOS group. Arterial oxygen partial pressure (PaO2) and arterial oxygen saturation (SaO2) results showed that HOS and HOHS could improve the oxygenation of the rats with CO poisoning. Compared with the CO group, the HOS group and the HOHS group had persistently neuroprotective effect on CO-induced brain injury, as assessed by modified neurological severity score (mNSS), furthermore, the HOHS group had better neurological functional recovery than the HOS group. The neuronal apoptosis induced by CO was also evaluated. Except the NG group, all the CO-poisoning groups had varying degrees of neuronal apoptosis. There was lesser degree of neuronal apoptosis in both the HOS group and the HOHS group than that in the CO group. Moreover, the HOHS group had more minor degree of neuronal apoptosis than the HOS group. Compared with the CO group, the free radicals production in the HOS group and the HOHS group were significantly inhibited. In addition, there were significantly difference in the free radicals production between the HOS group and the HOHS group. We could conclude that HOHS exerted a stronger neuroprotective effect against CO-induced brain injury than HOS, and the neuroprotective mechanism of HOHS may be related with inhibition of both neuronal apoptosis and free radicals.

Pressure support ventilation mode versus pressure support ventilation+T-piece trial as a weaning modality in mechanically ventilated patients with chronic obstructive pulmonary disease

BackgroundPressure support ventilation (PSV) mode and T-piece trial were used in weaning of mechanically ventilated (MV) patients with chronic obstructive pulmonary disease (COPD). Thus, the objective of study is to assess the value of adding T-piece trial to PSV mode in weaning off patients with COPD.Patients and methodsA total of 80 MV patients with COPD admitted to respiratory ICU were divided into two groups: group I included 40 patients who were weaned off by PSV mode and group II included 40 patients who were weaned off by PSV mode and T-piece trial.ResultsThe mean age of patients was 62 years. Overall, 73.8% were males and 73.75% were smokers. There were no significant differences between both groups regarding age, sex, BMI, smoking status, Acute Physiology and Chronic Health Evaluation score, exacerbation frequency, and hospital admission. Moreover, there was no significant differences between both groups regarding vital capacity, negative inspiratory force, rapid shallow breathing index, partial arterial oxygen pressure, partial arterial carbon dioxide pressure, and arterial oxygen saturation at the end of PSV mode in both groups. A significant decline in partial arterial oxygen pressure and arterial oxygen saturation and increase in partial arterial carbon dioxide pressure were observed in group II patients after adding T-piece trial. A total of 34 (85%) patients were successfully extubated in group I, whereas 33 (82.5%) patients were successfully extubated in group II. Period of MV, duration of weaning, ICU stay, and mortality were significantly higher in group II patients.ConclusionT-piece trial after PSV mode has no role in weaning; moreover, it causes more complications and leads to longer duration of weaning.

PO-037 Validation Of Capillary Blood Gas Analysis For The Assessment Of Training Load In Track Cycling

Objective The energy supply of daily training of track cycling should be mainly by anaerobic metabolism, which can make the blood buffer capacity facing huge Challenge and being improved. The arterialized capillary blood gas analysis can be a reliable method to evaluate the blood status of base-acid balance, which may reflect the effect of exercise intensity on blood buffer system. The paper validate the blood gas analysis as a reliable method for evaluating the total periodical training load of track cyclists.&#x0D; Methods Five male and five female elite track cyclists performed two phases (four weeks per phase) of training respectively. The content included the track specific, strength and aerobic training. The Borg's Rating of Perceived Exertion (RPE) Scale (0-11) was recorded in the ten minutes after each session and calculated the session RPE (sRPE). The total inertial load (TIL) was calculated by sRPE sum from Monday to Thursday. The arterialized capillary blood gas analysis was performed at 7:00 AM on Monday and Friday. The delta value (ΔPH, ΔPCO2, ΔTCO2, ΔHCO3-, ΔBE, ΔPO2, ΔSO2) were calculated by Friday minus Monday. Pearson's linear correlation was applied to calculate the correlation between TIL and delta value. Independent t test was used to test the differences between two genders.&#x0D; Results There was the moderate correlation between TIL with ΔPH and ΔHCO3- (Correlation Coefficient= 0.712 and 0.642 respectively, P&lt;0.01). But other blood gas indexes didn’t show the obvious relationship with TIL (Correlation Coefficient &lt; 0.5). There was no differences for TIL between male and female (3870.1±788.4 vs. 4130.2±716.7, P&gt;.05). Moreover, ΔHCO3- of male was significant more than female by 95.1% (P&lt;0.01). There were significant correlation between TIL and ΔPH for both male and female (Correlation Coefficient= 0.785 and 0.812 respectively, P&lt;0.01), and between TIL and ΔPH for both male and female (Correlation Coefficient= 0.662 and 0.658 respectively, P&lt;0.01).&#x0D; Conclusions The PH value and bicarbonate radical of blood should be sensitive to the high intensity track cycling training, which can be the valid to evaluate the inertial load. However, gender has no influence on evaluating. The oxygen partial pressure and oxygen saturation of blood can not reflect the training load accurately.

Evaluation of Cardiorespiratory Effects of Dexmedetomidine Isolated and Associated With Morphine in Bitches Submitted to Elective Ovariossalpingohisterectomy under General Inhalation Anesthesia

Background: Elective ovariossalpingohysterectomy is one of the most accomplished surgeries in veterinary practice, presenting moderate degree of pain. Aiming at balanced anesthesia, α2-agonists have been increasingly used, with dexmedetomidine being characterized by its sympatholytic, sedative, analgesic properties and synergism with opioids, benzodiazepines and other drugs. The objective of this study was to evaluate the effects of dexmedetomidine alone and associated with morphine under the cardiovascular, respiratory and body temperature variables in the pre and trans-operative periods in bitches submitted to elective ovariossalpingohisterectomy under general inhalation anesthesia.Materials, Methods &amp; Results: Sixteen bitches were used in this study, which were submitted to elective ovariossalpingohisterectomy, all of which were clinically healthy based on clinical and hematological results. The animals were randomized into two groups, in which intramuscular dexmedetomidine alone and 5 µg/kg (DG) and 0.3 mg/kg morphine (GDM). In both groups, anesthesia was induced with propofol administered and maintained with isoflurane diluted in 100% oxygen administered through a calibrated vaporizer and appropriate anesthetic system based on the weight of the animal and kept under spontaneous ventilation. After stabilization of the patient, the surgical procedure started, which lasted 45 minutes. The parameters evaluated were heart rate (HR), respiratory rate (ƒ), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), body temperature (TºC), expired isoflurane concentration , partial carbon dioxide gas pressure (ETCO2) and oxygen saturation in hemoglobin (SatO2), which were measured before and after the application of preanesthetic medication and at specific surgical times: 5 and 15 min after anesthetic induction; during the incision of the skin; muscle incision; ligation of the left ovary; ligation of the right ovary; ligation of the uterine body; laparorrafia; suture and at the end of surgery. A significant difference was observed between the groups in respiratory rate, systolic blood pressure, body temperature, partial pressure of carbon dioxide, saturation of oxygen in hemoglobin and pH, only in some times evaluated. GDM bradycardia occurred 30 min after preanesthetic medication; acidemia and mild to moderate hypercapnia in both groups, being more pronounced in GDM, although without statistical difference, and hypothermia. The concentration of isoflurane expired in both groups was higher during the muscle incision until laparorrhaphy compared to the other surgical times.Discussion: The results of this study show that there was adequate analgesia during the elective ovarian resection procedure, considering that the values found during the surgery were relatively lower than the baseline values and within the physiological limits for the species, even during the moments of greater painful stimulation, such as ligation of the ovaries and ligation of the uterine body. In the GDM group, bradycardia occurred after 30 min of pre-anesthetic medication, but its occurrence was transient and without interfering with blood pressure, increasing to the next evaluation time and stabilizing in physiological values for the species. There was also a gradual reduction in respiratory rate in both groups over time, with an increase in PaCO2 in GDM at the end of surgery, indicating respiratory depression, as well as a reduction in pH in both groups at all times.

Effects of pumpless extracorporeal lung assist on hemodynamics, gas exchange and inflammatory cascade response during experimental lung injury.

Pumpless extracorporeal lung assist (pECLA) has been reported to efficiently remove the systemic CO2 production and provide mild to moderate oxygenation, thereby allowing for ventilator settings and modes prioritizing oxygenation and lung protection. However, an adequate bypass flow, the capacity to provide respiratory support and the effect on the inflammatory cascade response and tissue perfusion require further study to be determined. After induction of acute lung injury (ALI) by oleic acid injection, pECLA was implemented in 12 anaesthetized and mechanically ventilated dogs for 48 h. Improved oxygenation [partial oxygen pressure (PaO2) and oxygen saturation (SaO2) was measured by arterial blood gas analysis, and increased by 29 and 18%, respectively] and CO2 elimination (partial CO2 pressure decreased by 43.35%) were obtained after pECLA implementation. A maximum arterio-venous shunt flow of up to 25% of the foundational CO resulted in stable hemodynamics. The pECLA procedure did not elicit any further increase in the concentration of tumor necrosis factor-α, interleukin (IL)-6, IL-8 and endothelin-1 compared with that in the group subjected to oleic acid injection only. In addition, the pECLA procedure had no effect on lactate levels and urine production. In conclusion, pECLA is an efficient and promising strategy for providing a mild to moderate oxygenation and adequate decarboxylation, while avoiding excessive inflammatory cascade response and tissue hypoperfusion in an experimental ALI model.

Clinical efficacy of transjugular intrahepatic portosystemic shunt in the treatment of hepatopulmonary syndrome.

Transjugular intrahepatic portosystemic shunt (TIPS) reduces the portal venous pressure of patients with hepatopulmonary syndrome (HPS).To describe the patients who underwent TIPS for the treatment of HPS.A retrospective study was performed on 81 patients with HPS and gastrointestinal hemorrhage treated with TIPS. Thirty patients underwent TIPS through the main portal vein (group A), 24 through the left branch of the portal vein (group B), and 27 through the right branch of the portal vein (group C). The partial pressure of arterial oxygen (PaO2), alveolar-to-arterial oxygen partial pressure gradient (A–aPO2), oxygen saturation (SO2), and complications were recorded and compared. The survival rate for each group was calculated.The technical success rate was 100% in the 3 groups. Preoperative portal vein pressure showed no significant differences between the 3 groups, which was decreased post-TIPS operation. In group A, PaO2 and SO2 were higher in 15 days and 3 months postoperative than preoperative (P < .05), whereas A–aPO2 was lower (P < .05). No difference occurred between 12 months post- and preoperative group. In group C, PaO2 and SO2 did not alter significantly at each time point after operation (P > .05), whereas A–aPO2 decreased at 3 months (P = .041) than preoperative. In group B, all indicators at each follow-up time point after TIPS were improved significantly as compared with the preoperative group (P < .05), which showed an excellent effect on hypoxemia treatment. Although the 1-year survival rate of 3 groups of patients was 92.85%, 90.90%, and 91.67%, respectively, the rate of hepatic encephalopathy and hepatic myelopathy was 33.33% (10/30), 16.67% (4/24), and 33.33% (9/27) after TIPS.TIPS reduced the pressure of the portal vein effectively and alleviated hypoxemia in most HPS patients successfully. Thus, the left branch of the portal vein is optimal for TIPS owing to fewer complications and efficacy in improving PaO2 as compared with the main portal vein and right branch.

Clinical efficacy of combinations of nebulised fluticasone, salbutamol and furosemide on lung function in premature calves with respiratory distress syndrome

Surfactant deficiency, poor development of the lung structure and fibrosis as a result of inflammation are thought to play an important role in the development of respiratory distress syndrome in premature calves. Nebulised steroid (fluticasone), bronchodilator (salbutamol) and diuretics (furosemide) can be used in combination alongside standard treatment procedures for premature calves, and might improve viability as observed in infants, foals and horses with pulmonary disorders. Twenty-five premature calves with respiratory distress syndrome were used in this study. Oxygen and supportive treatment were administered to all groups. The first group was used as a control group (Group 1). The nebulised drug combinations were as follows: Group 2: fluticasone + salbutamol, Group 3: salbutamol + furosemide, Group 4: fluticasone + furosemide and Group 5: fluticasone + salbutamol + furosemide. During the 72-h time period of the study, fluticasone (15 µg/kg/12 h), salbutamol (0.025 mg/kg/6 h) and furosemide (1 mg/kg/12h) were applied for 5 min. Arterial blood samples were collected from the auricular artery at 0 h and at 1, 24, 48 and 72 h for blood gas analysis. Significant (P &amp;lt; 0.05) increases in arterial partial oxygen, oxygen saturation and peripheral oxygen saturation and decreases in arterial partial carbon dioxide, lactate and respiration rate were observed in all the nebulised treatment groups, while a statistical difference was observed only for arterial partial carbon dioxide in control group. When comparing the treated groups with the control, it may be concluded that nebulised drugs are highly effective in the therapy of premature calves with respiratory distress syndrome, while the different nebulised groups exhibited similar efficacies.

Reversed patent ductus arteriosus and multiple congenital malformations in an 8‐day‐old Arabo‐Friesian foal

SummaryAn 8‐day‐old Arabo‐Friesian filly was presented with signs of severe dyspnoea, tachypnoea, coughing and cyanotic mucous membranes. On auscultation, a bilateral grade V/VI continuous heart murmur and heart rate of 155 beats/min (sinus tachycardia) were detected. Lung ultrasonography revealed pronounced comet tail artefacts indicating lung oedema. Echocardiography showed right ventricular hypertrophy, a 1.2 cm muscular ventricular septal defect with a left‐to‐right shunt, a stenotic bicuspid pulmonary valve and severe mitral and tricuspid valve regurgitation. Tricuspid regurgitation peak velocity indicated a right ventricular systolic pressure of 119 mmHg. The pulmonary artery was severely dilated and a 1 cm diameter patent ductus arteriosus was found. Colour flow Doppler showed systolic ductal flow reversal with right‐to‐left shunting through the ductus. Arterial partial oxygen pressure and saturation were lower in the metatarsal artery (25 mmHg, saturation 52.6%) than in the carotid artery (31 mmHg, saturation 64.3%). Due to the poor prognosis, the foal was subjected to euthanasia and necropsy confirmed the ultrasonographic findings. Patent ductus arteriosus is a rare condition and occurs most frequently in combination with tetralogy and pentalogy of Fallot. A genetic basis for congenital cardiac disease, especially for ventricular septal defects, in Arabians and for aortic rupture and aorto‐pulmonary fistulation in Friesians has been reported. Whether cross‐breeding leads to an increased prevalence is unknown. This is the first case report with echocardiographic visualisation of reversed ductal flow in a neonatal Arabo‐Friesian foal.

Hemodynamic parameters and vessel tortuosity: an investigation with a mesenterial vascular network

Purpose: The effect of hemodynamic parameters on vessel tortuosity remains un-clear. Here we investigate the correlation of tortuosity with a set of hemodynamicparameters in a mesenterial vascular network.Methods: A mesenterial vascular network of 389 vessels (131 arteries, 132 veins, and 126 capillaries) was imaged. Eleven hemodynamic parameters were measured (pressure, wall shear stress, diameter, blood velocity and flow, viscosity, haematocrit, partial oxygen saturation, oxygen saturation, wall thickness, and local vessel density). Tortuosity was assessed quantitatively with a validated algorithm and correlation computed with subsets of hemodynamic parameters selected by a lasso regressor.Results: Results suggest that tortuosity is related to pressure, wall shear stress, diameter, blood velocity, viscosity, partial but not full oxygen saturation, and wall thickness for the arteries; diameter, blood flow, hematocrit, and density for the veins; and viscosity (but not hematocrit), partial and full oxygen saturation, and density for the capillaries. The combination of hemodynamic parameters correlating best with tortuosity is the set of all parameters except density (r = 0.64, p &lt; 0.01), using as tortuosity definition the set of tortuosity features (geometric measures) correlating best with a single hemodynamic factor for the arteries.Conclusion: This pilot suggests two general conclusions. First, the quantitative definition of tortuosity (i.e., the set of geometric features adopted) should be tuned to the specific data and problem considered. Second, tortuosity is caused by a combination of hemodynamic factors, not a single one.

The multi-level impact of chronic intermittent hypoxia on central auditory processing

During hypoxia, the tissues do not obtain adequate oxygen. Chronic hypoxia can lead to many health problems. A relatively common cause of chronic hypoxia is sleep apnea. Sleep apnea is a sleep breathing disorder that affects 3–7% of the population. During sleep, the patient's breathing starts and stops. This can lead to hypertension, attention deficits, and hearing disorders. In this study, we apply an established chronic intermittent hypoxemia (CIH) model of sleep apnea to study its impact on auditory processing. Adult rats were reared for seven days during sleeping hours in a gas chamber with oxygen level cycled between 10% and 21% (normal atmosphere) every 90s. During awake hours, the subjects were housed in standard conditions with normal atmosphere. CIH treatment significantly reduces arterial oxygen partial pressure and oxygen saturation during sleeping hours (relative to controls). After treatment, subjects underwent functional magnetic resonance imaging (fMRI) with broadband sound stimulation. Responses are observed in major auditory centers in all subjects, including the auditory cortex (AC) and auditory midbrain. fMRI signals from the AC are statistically significantly increased after CIH by 0.13% in the contralateral hemisphere and 0.10% in the ipsilateral hemisphere. In contrast, signals from the lateral lemniscus of the midbrain are significantly reduced by 0.39%. Signals from the neighboring inferior colliculus of the midbrain are relatively unaffected. Chronic hypoxia affects multiple levels of the auditory system and these changes are likely related to hearing disorders associated with sleep apnea.

Alfaxalone for maintenance of anaesthesia in ponies undergoing field castration: continuous infusion compared with intravenous boluses

ObjectiveTo compare alfaxalone as continuous intravenous (IV) infusion with intermittent IV injections for maintenance of anaesthesia in ponies undergoing castration. Study designProspective, randomized, ‘blinded’ clinical study. AnimalsA group of 33 entire male Welsh ponies undergoing field castration. MethodsAfter preanaesthetic medication with IV detomidine (10 μg kg−1) and butorphanol (0.05 mg kg−1), anaesthesia was induced with IV diazepam (0.05 mg kg−1) followed by alfaxalone (1 mg kg−1). After random allocation, anaesthesia was maintained with either IV alfaxalone 2 mg kg−1 hour−1 (group A; n = 16) or saline administered at equal volume (group S; n = 17). When necessary, additional alfaxalone (0.2 mg kg−1) was administered IV. Ponies were breathing room air. Using simple descriptive scales, surgical conditions and anaesthesia recovery were scored. Total amount of alfaxalone, ponies requiring additional alfaxalone and time to administration, time from induction to end of infusion and end of infusion to standing were noted. Indirect arterial blood pressure, pulse and respiratory rates, end-expiratory carbon dioxide partial pressure and arterial haemoglobin oxygen saturation were recorded every 5 minutes. Data were analysed using Student t, Mann–Whitney U and chi-square tests, where appropriate (p < 0.05). ResultsTotal amount of alfaxalone administered after induction of anaesthesia (0.75 ± 0.27 versus 0.17 ± 0.23 mg kg−1; p < 0.0001) and time to standing (14.8 ± 4 versus 11.6 ± 4 minutes; p = 0.044) were higher in group A compared to group S. Ponies requiring additional alfaxalone boluses [four (group A) versus seven (group S)] and other measured variables were similar between groups; five ponies required oxygen supplementation [three (group A) versus two (group S)]. Conclusion and clinical relevanceContinuous IV infusion and intermittent administration of alfaxalone provided similar anaesthesia quality and surgical conditions in ponies undergoing field castration. Less alfaxalone is required when used intermittently.

Short term general anesthesia for retro-bulbar block in ophthalmic surgery generates no significant hypercapnia.

To assess the impact of short time hypnosis for retro-bulbar anesthesia on ventilation in patients undergoing ophthalmic surgery of the anterior eye chamber. In all patients, a combined continuous transcutaneous carbon dioxide tension (PtcCO2) and partial oxygen saturation (SpO2) measurement was applied in addition to routine monitoring. To enable unconscious application of retro-bulbar anesthesia, intravenous thiopental was given in one to multiple bolus doses. Transient breathing support included chin lift, Esmarch maneuver and manual hand-bag ventilation via face mask. Main endpoints were apnea time, recovery time according to the Richmond Agitation Sedation Scale, as well as SpO2 and PtcCO2 readings at predefined time points. Fifty-two patients with a mean age of 68 ± 13years were included. Average thiopental dose was 2.7 ± 0.6mg/kg. In seven (13.5%) patients repeated doses of thiopental were necessary to a total of 3.3 ± 1.1mg/kg. Except one patient, no severe, significant or clinical relevant hypercapnia or desaturation periods were observed, and the occurring elevation of PtcCO2 values did not correlate with the application of repeated doses of thiopental or the need for the Esmarch maneuver. Higher PtcCO2 values were associated with the presence of hypertension and smoking. Apnea (p < 0.001) and recovery (p = 0.003) time were significantly prolonged in the patients needing the Esmarch maneuver. Short term anesthesia with thiopental in ophthalmic surgery is associated with a mild but not clinically relevant hypercapnia.

Efficacy and safety of single versus repeated stepwise cycling recruitment maneuver during one-lung ventilation in patients with normal pulmonary function undergoing video-assisted thoracoscopic lung surgery: a randomized, controlled trial

Background One-lung ventilation (OLV)-associated hypoxemia is a major concern and a challenge for the anesthesiologist. Lung recruitment maneuvers (RMs) are ventilator strategies in which the main goal is to restore the functional residual capacity and improve arterial oxygenation. Hemodynamic side effects are mainly associated with ‘fast’ RM not with ‘slow’ cycling RM and their effects are self-limited; therefore, they must be performed repetitively. Aim The aim of this study was to evaluate the efficacy and safety of single versus repeated stepwise cycling RMs during OLV in patients with normal lung function. Settings and design The study design is a randomized, double-blinded, controlled one. Patients and methods Sixty adult patients of ASA I–II who were scheduled for elective thoracoscopic lung surgery were randomized into groups C, single recruitment maneuver (SRM), and repeated recruitment maneuver (RRM) comprising 20 patients each. Group C patients received standard ventilation protocol: volume-controlled ventilation mode, VT 6 ml/kg, I : E ratio 1 : 2, positive end expiratory pressure (PEEP) 5 cmH2O, and respiratory rate 10–12 breaths/min. SRM patients received standard ventilation protocol with one alveolar RM 10 min after initiation of OLV with a PEEP of 10 cmH2O until end of surgery. RRM patients received standard ventilation protocol with first RM 10 min after initiation of OLV and then repeated every 30 min during OLV and a PEEP of 10 cmH2O until end of surgery. The following were assessed: hemodynamic parameters – heart rate, mean arterial blood pressure, and central venous pressure; respiratory mechanical parameters – peak airway pressure (Paw-peak), plateau pressure (Paw-plat), and static lung compliance; and oxygenation parameters – partial arterial oxygen tension (PaO2), PaO2/FiO2, and oxygen saturation (SpO2). Results PaO2 and PaO2/FiO2 ratio increased in the SRM and RRM groups after RM from T2 (10 min after first RM) to T4 (45 min from first RM), with a significant difference compared with group C (P Conclusion Single or repeated cycling RM was considered effective with high safety profile in patients with normal pulmonary function undergoing thoracoscopic lung surgery using OLV.

Predicting arterial blood gas and lactate from central venous blood analysis in critically ill patients: a multicentre, prospective, diagnostic accuracy study

BackgroundThe estimation of arterial blood gas and lactate from central venous blood analysis and pulse oximetry (SpO2) readings has not yet been extensively validated. MethodsIn this multicentre, prospective study performed in 590 patients with acute circulatory failure, we measured blood gases and lactate in simultaneous central venous and arterial blood samples at 6 h intervals during the first 24 h after insertion of central venous and arterial catheters. The study population was randomly divided in a 2:1 ratio into model derivation and validation sets. We derived predictive models of arterial pH, carbon dioxide partial pressure, oxygen saturation, and lactate, using clinical characteristics, SpO2, and central venous blood gas values as predictors, and then tested their performance in the validation set. ResultsIn the validation set, the agreement intervals between predicted and actual values were −0.078/+0.084 units for arterial pH, −1.32/+1.36 kPa for arterial carbon dioxide partial pressure, −5.15/+4.47% for arterial oxygen saturation, and −1.07/+1.05 mmol litre−1 for arterial lactate (i.e. around two times our predefined clinically tolerable intervals for all variables). This led to ∼5% (or less) of extreme-to-extreme misclassifications, thus giving our predictive models only marginal agreement. Thresholds of predicted variables (as determined from the derivation set) showed high predictive values (consistently >94%), to exclude abnormal arterial values in the validation set. ConclusionsUsing clinical characteristics, SpO2, and central venous blood analysis, we predicted arterial blood gas and lactate values with marginal accuracy in patients with circulatory failure. Further studies are required to establish whether the developed models can be used with acceptable safety.

Correlation between some arterial and venous blood gas parameters in healthy newborn Martina Franca donkey foals from birth to 96 hours of age

In neonatology, blood gas analysis is a useful tool in the evaluation of the health of newborns and plays a key role in early detection of critically ill subjects. Because blood gas analysis parameters have not previously been studied in any depth in donkey foals, this study was performed on 16 healthy Martina Franca donkey foals born after an uncomplicated delivery. Arterial and venous blood samples were collected at 5 minutes and at 12, 24, 72, and 96 hours of age. Blood gas analysis was performed by a portable analyzer, measuring arterial and venous total carbon dioxide, carbon dioxide partial pressure (pCO2), oxygen partial pressure (pO2), oxygen saturation (sO2), bicarbonate, base excess (BE), pH, and lactate (LT). Lower blood pH values, pO2 and sO2, and a higher level of lactate were found at birth in comparison with subsequent sampling times. This moderate acidotic profile disappeared at 12 hours, when all the parameters became constant until the end of the study period. As expected, significant differences between arterial and venous blood gas parameters related to the oxygenation, such as pO2 and sO2, and partially carbon dioxide partial pressure were found, whereas total carbon dioxide, pH, BE, and LT were comparable in arterial and venous blood samples. For these latter parameters, the highly significant correlation between arterial and venous findings suggests that venous samples could be an acceptable alternative to the arterial sample for blood gas analysis in newborn donkey foals, when the oxygenation status of the patient is not the first goal of patient analysis.

Assessment of aversion and unconsciousness during exposure to carbon dioxide at high concentration in lambs

AbstractThe most widely used stunning method in sheep is electrical. However, in lambs, this method leads to rupture of the blood vessels, provoking ecchymoses. In pigs (Sus scrofa), the use of CO2-stunning systems has increased in popularity due to positive effects on meat quality and animal welfare (movement of animals in groups). The aim here was to assess the effectiveness of a progressive exposure to 90% carbon dioxide (CO2) in inducing unconsciousness in lambs (Ovis aries) through changes in the middle latency auditory-evoked potentials (MLAEP) of the central nervous system (CNS), blood parameters (pH, carbon dioxide partial pressure (pCO2), oxygen partial pressure (pO2), oxygen saturation (SatO2) and bicarbonate (HCO3J, behaviour (head-shaking, sneezing, gasping and gagging) and physiological reflexes (corneal reflex, breathing and sensitivity to pain). Fourteen male lambs of the Ripollesa breed, weighing between 19 and 25 kg were progressively exposed to an atmosphere of 90% CO2 over 66 s. All blood parameters changed between 23 and 43 s after the onset of the immersion. The MLAEP did not decrease significantly until after 48 s exposure to CO2, suggesting an absence of auditory-evoked brain activity. Before that, lambs exhibited head-shaking and sneezing starting at 10.6 (± 0.77) s, and gasping starting at 20.6 (± 1.36) s. After exposure, all animals showed absence of breathing and sensibility to pain, and 36% of them absence of corneal reflex. The pH and pCO2 recovered basal values at 90 and 120 s, respectively, after the end of the exposure. The burst suppression index (BS%) and the A-Line ARX index (AAI) recovered basal levels at 116 and 159 s, respectively. Exposure to CO2 at high concentration induces effective stunning in sheep for a period of 124 s. However, during exposure, the animals exhibited signs of aversion and breathlessness.

The effect of a forced-air warming blanket on patients' end-tidal and transcutaneous carbon dioxide partial pressures during eye surgery under local anaesthesia: a single-blind, randomised controlled trial.

Surgical drapes used during eye surgery are impermeable to air and hence risk trapping air underneath them. We investigated the effect of a forced-air warming blanket on carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia without sedation. Forty patients of ASA physical status 1 and 2 were randomly assigned to either the forced-air warmer (n = 20) or a control heated overblanket (n = 20). All patients were given 1 l.min(-1) oxygen. We measured transcutaneous and end-tidal carbon dioxide partial pressures, heart rate, arterial pressure, respiratory rate, temperature and oxygen saturation before and after draping, then every 5 min thereafter for 30 min. The mean (SD) transcutaneous carbon dioxide partial pressure in the forced-air warming group stayed constant after draping at 5.7 (0.2) kPa but rose to a maximum of 6.4 (0.4) kPa in the heated overblanket group (p = 0.0001 for the difference at time points 15 min and later). We conclude that forced-air warming reduces carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia.

Role of angiotensin-converting enzyme (ACE) and ACE2 in a rat model of smoke inhalation induced acute respiratory distress syndrome

Smoke inhalation induced acute respiratory distress syndrome (ARDS) has become more and more common throughout the world and it is hard to improve the outcome. The present research was to investigate possible roles of angiotensin-converting enzyme (ACE) and ACE2 in lung injury resulted from smoke exposure. Rats were exposed to dense smoke to induce ARDS. Histological changes, blood gases, bronchoalveolar lavage fluids (BALF) and wet-to-dry weight were analyzed to evaluate lung injury after smoke inhalation; beside, we also measured the expression of ACE and ACE2 at different time points to explore the possible mechanism of those changes. The results showed that pH of arterial blood, partial blood oxygen (PaO2) and blood oxygen saturation (SO2) decreased after smoke inhalation at different time points (P<0.01); while, partial blood carbon dioxide (PaCO2), wet-to-dry weight ratio, leukocytes count, protein concentration and inflammatory cytokines in BALF increased after smoke exposure (P<0.01). More importantly, both immunohistochemical staining and Western blot results showed that ACE and ACE2 expression in lungs from the experimental groups significantly increased compared with that of the control group (P<0.05). This study indicated that inflammation pulmonary edema and histological changes resulted from smoke inhalation induced lung injury were possibly attributed to abnormal expression of ACE and ACE2 related pathway.