Accumulation of carbon dioxide under ophthalmic drapes during eye surgery: a comparison of three different drapes.

BACKGROUNDCarbon dioxide concentration under ophthalmic drapes increases during eye surgery under local anaesthesia. A new prototype has been designed which combines continuous suction of carbon dioxide enriched air and continuous...

BACKGROUND/AIMHypoxia and carbon dioxide rebreathing are potential problems during eye surgery in spontaneously breathing patients. The aim of the present study was to determine effectiveness of nasal application of oxygen...

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.

High-flow nasal cannula oxygen therapy reduces the arterial partial pressure of carbon dioxide and acute exacerbation but does not increase exercise capacity or decrease hospitalisation or mortality. The study aimed to test the hypothesis that in chronic obstructive pulmonary disease patients, the use of high-flow nasal cannula decreases arterial partial pressure of carbon dioxide and increases the partial pressure of oxygen and 6-min walking distance. PubMed, Embase and the Cochrane library were searched for eligible studies published from database inception to November 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist). The primary outcomes were partial pressure of carbon dioxide and partial pressure of oxygen, and the secondary outcomes were transcutaneous partial pressure of carbon dioxide and 6-min walking distance. Nine studies (680 patients) were included. high-flow nasal cannula did not decrease partial pressure of carbon dioxide compared with the control interventions (mean difference=-0.81, 95% confidence interval: -2.68 to 1.06, p=.395; I2 =42.9%, pheterogeneity =.105). high-flow nasal cannula decreased partial pressure of carbon dioxide compared with long-term oxygen therapy (mean difference=-3.25, 95% confidence interval: -5.65 to -0.85, p=.008; I2 =0%, pheterogeneity =.375); no difference was observed for the control modalities. high-flow nasal cannula resulted in better partial pressure of carbon dioxide compared with control interventions in hypoxemic patients (mean difference=-2.59, 95% confidence interval: -4.82 to -0.35, p=.023; I2 =32.5%, pheterogeneity =.224), but not in other types of patients. high-flow nasal cannula did not increase partial pressure of oxygen compared with the control interventions (mean difference=1.17, 95% confidence interval: -1.50 to 3.83, p=.390; I2 =0%, pheterogeneity =.660). high-flow nasal cannula decreased transcutaneous carbon dioxide tension (transcutaneous partial pressure of carbon dioxide) compared with the control interventions (mean difference=2.37, 95% confidence interval: 0.07-4.68, p=.044; I2 =8.7%, pheterogeneity =.295). high-flow nasal cannula increased 6-min walking distance compared with the control interventions (mean difference=18.22, 95% confidence interval: 0.86-,35.57, p=.040; I2 =0%, pheterogeneity =.918). The sensitivity analyses showed that the results were robust. High-flow nasal cannula did not significantly decrease partial pressure of carbon dioxide or increase partial pressure of oxygen in chronic obstructive pulmonary disease patients, which is different from the previous meta-analysis, but it decreases transcutaneous partial pressure of carbon dioxide and increased 6-min walking distance. This meta-analysis shows that in patients with chronic obstructive pulmonary disease, high-flow nasal cannula improves both transcutaneous partial pressure of carbon dioxide and 6-min walking distance, suggesting the high-flow nasal cannula has benefits in the management of chronic obstructive pulmonary disease. Considering that the literature suggests no impact of high-flow nasal cannula on hospitalisation and mortality, the benefits of high-flow nasal cannula might be limited to the patients who survive the chronic obstructive pulmonary disease events. Still, the global impact of high-flow nasal cannula on the quality of life of patients with chronic obstructive pulmonary disease should be examined.

Objective To observe the effect of permissive hypercapnia(PH) on postoperative cognitive function in patients with carotid endarterectomy(CEA). Methods Forty patients who were selected for unilateral CEA were divided into two groups, aged 40-70 y, sex unlimited, American Society of Anesthesiologists(ASA) grade Ⅱ-Ⅲ. The patients were divided into two groups by random numerical table method: conventional ventilation group (group R) and PH group (group H). The parameters of mechanical ventilation in group R with hypercapnia ventilation were as follows: tidal volume (VT) was 8-10 ml/kg, respiratory rate (RR) was 12-16 bpm, arterial partial pressure of carbon dioxide (PaCO2) was 35-45 mmHg (1 mmHg=0.133 kPa), the parameters of mechanical ventilation in group H were set as follows: VT was 6-8 ml/kg, RR was 12-14 bpm, PaCO2 was 46-55 mmHg. The basic indexes such as operation time, carotid artery occlusion time, extubation time and post-anesthesia care unit (PACU) stay time were recorded. Cerebral oxygen saturation (rSO2) was monitored by near infrared spectroscopy (NIR). The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate, saturation of pulse oximetry (SpO2), end-tidal carbon dioxide partial pressure (PETCO2) and rSO2 were recorded before operation (T0), immediately after anesthesia induction (T1), 10 min after anesthesia induction(T2), immediately before carotid artery occlusion (T3), immediately after carotid artery occlusion (T4), and at the end of operation (T5). The cognitive function of the patients was evaluated by Mini-Mental State Examination (MMSE) scores at T0, 24 h, 48 h, 3 d and 7 d after operation. Results There were no significant difference in operation time, carotid artery occlusion time, extubation time and PACU residence time between the two groups(P>0.05). Compared with group R, PETCO2, rSO2 and MMSE score increased in group H at the time point of T2-T5, the MMSE score increased at 24 h, 48 h after operation, which alleviated the occurrence of postoperative cognitive dysfunction (POCD) in cognitive impairment after operation (P<0.05). Compared with T0, the rSO2 at T2-T5 time point in two groups was lower (P<0.05), MMSE scores decreased significantly at 24 h, 48 h, 3 d and 7 d after operation(P<0.05). Conclusions PH ventilation can improve cerebral oxygen metabolism and reduce the occurrence of POCD after operation. Key words: Hypercapnia; Carotid endarterectomy; Cognitive function; Brain oxygen

Objective To observe the effects of low levels of positive end expiratory pressure on cerebral hemodynamics in patients with gastric cancer undergoing laparoscopic radical resection surgery under general anesthesia. Methods 80 patients(ASAⅠ-Ⅱ), scheduled to undergo laparoscopic radical gastrostomy, were randomly divided into group A, and group B, each group had 40 cases. The ventilation parameters of group A:tidal volume(VT): 8 ml/kg, respiratory rate(RR): 12 min, positive end expiratory pressure (PEEP):5 cm H2 O(1 cm H2 O= 0.098 kPa). Group B was:VT:8 ml/kg, RR:12 min.Recording the average blood flow velocity in the middle cerebral artery(Vm),mean arterial pressure(MAP),heart rate(HR), transcutaneous oxygen saturation(SpO2),end-tidal carbon dioxide pressure(PetCO2)of the two group before pneumoperitoneum(T0),30 min after pneumoperitoneum(T1), 1 hours(T2)and 2 hours(T3)after pneumoperitoneum. Blood samples of jugular bulb and radial artery were obtained at each time point for blood gas analysis, detection the arterial oxygen pressure(PaO2), arterial carbon dioxide pressure(PaCO2), arterial oxygen saturation(SaO2), hemoglobin concentration(Hb), internal jugular venous blood oxygen partial pressure(PjvO2), internal jugular venous oxygen saturation(SjvO2), jugular venous oxygen content(CjvO2), and arterial-jugular venous oxygen content difference(Da-jvO2). Results Compared with T0,the Vm,SjvO2, PaCO2 of the two groups increased significantly at each time point(P<0.05).But the Vm, SjvO2 of group A at T2 was significantly lower than that in group B(P<0.05),and the PaCO2 of group A at T1 and T2 were(35.5±2.7),(40.7±3.5)mm Hg respectively, which significantly lower than that of group B [(39.9±3.1),(49.4±4.7)mm Hg,P<0.05].And the Vm of group A at T2 was(68.9±8.1)cm/s,significantly lower than that of group B(P<0.05).Compared with T0, the Da- jvO2 at T2 of two groups decreased significantly(P<0.05),and between the two groups, A group decreased significantly than that in B group(P<0.05). Conclusion The low level of positive end expiratory pressure in patients undergoing laparoscopic radical gastrostomy with general anesthesia can effectively reduce the hypercapnia during operation, and improve cerebral hyperperfusion state,so as to improve the cerebral blood flow and improve cerebral oxygen supply and demand balance. Key words: Positive end expiratory pressure; Laparoscopy; Radical gastrectomy; Cerebral hemodynamics

Objective To analysis the transcutaneous carbon dioxide pressure(TcpCO2)in very low birth weight infant (VLBW) and extremely low birth weight infant (ELBW) after the time of tube drawing, and further guidance the management of premature ventilator breathing. Methods Premature infants with gestational age less than 32 weeks, birth weight below 1 500 g, hospitalized from March 2016 to December 2018 in our hospital, who needed early mechanical ventilation due to respiratory distress within 24 hours after birth and intended to be withdrawn were enrolled.Fifty-five infants in the observation group were monitored by TcpCO2 and blood gas was collected at 1 h, 6 h, 12 h, 24 h, 48 h, and 72 h after weaning; 55 infants in the control group were collected arterial blood gas only.When TcpCO2 monitoring and PaCO2 indicated hypercapnia, clinical intervention was actively given.The value of blood gas PaCO2 in the two groups and the TcpCO2 value of the observation group were recorded at different time points (1 h, 6 h, 12 h, 24 h, 48 h, 72 h) after weaning, and the failure of weaning was recorded in both group. Results There was no significant difference in the general information (gender, gestational age, birth weight, and whether prenatal maternal glucocorticoids) between the two groups (P>0.05). There were no significant differences in mechanical ventilation time, noninvasive ventilation mode and time between the two groups(P>0.05). The failure rate of withdrawal within 24 h and 72 h was lower in the observation group than the control group[3.6% (2/55) vs.14.0% (8/55), 7.3% (4/55) vs. 21.0% (12/55)], the difference was statistically significant (P 0.05). The values of TcpCO2 and PaCO2 had no significant difference in the observation group at the same time point (P>0.05), and there was a correlation between them(r=0.761, P<0.05). Conclusion VLBW and ELBW undergoing mechanical ventilation are given continuous TcpCO2 monitorings after weaning, which not only has the characteristics of continuous and non-invasive monitoring, but also help to identify hypercapnia early and give symptomatic treatment, and reduce the incidence of weaning failure.And it proves a good correlation between TcpCO2 and PaCO2. Key words: Transcutaneous carbon dioxide pressure; Partial pressure of carbon dioxide; Extubation withdrawal; Very low birth weight infant; Extremely low birth weight infant

Objective To explore the treatment effect and prognosis of BiPAP non-invasive ventilator of sequential mechanical ventilation for the treatment of acute exacerbation of chronic obstructive pulmonary disease(AECOPD)complicated with pulmonary encephalopathy,and to provide the basis for clinical therapy. Methods According to the digital table,62 AECOPD patients with pulmonary encephalopathy were selected and randomly divided into the two groups.And 30 cases in the control group received routine treatment,and 32 cases in the observation group received BiPAP non-invasive ventilator sequential ventilation.The partial pressure of oxygen(PaO2),partial pressure of carbon dioxide(PaCO2)and oxygen saturation(SaO2)before and after treatment,the changes of heart rate,respiratory rate and average arterial pressure of the two groups and the improvement time were observed. Results PaO2 and SaO2 of the two groups after treatment were higher than those before treatment(t= 12.30,10.37,11.42,13.71,all P<0.05).PaO2 and SaO2 of the observation group after treatment were(77.14±4.16)mm Hg and(90.37±2.04)%, which were higher than the control group after the treatment(72.96±3.22)mm Hg and(85.80±1.96)%(t= 6.58,7.14,all P<0.05).PaCO2 of the two groups after treatment was lower than that before treatment(t= 9.25,10.22,all P<0.05).PaCO2 of the observation group after treatment was(50.12±2.86)mm Hg,which was lower than that before treatment(54.27±3.01)mm Hg(t= 6.29,P< 0.05).The heart rate,respiratory rate and mean arterial pressure of the control group and the observation group after treatment were lower than before treatment(t= 10.11,9.43,8.66,11.28,8.56,9.15,all P< 0.05).The heart rate,respiratory rate and mean arterial pressure of the observation group after treatment were(76.52±4.35)times/min,(20.35±1.08)times/min and(83.26±3.07)mm Hg,which were lower than those of the control group after treatment(t= 6.44,5.82,6.70,all P< 0.05).The blood gas improvement time,ventilation time and hospitalization time of the observation group were(4.06±1.17)d,(4.53±0.90)d and(16.18±2.20) d, which were lower than the control group(t= 6.13, 7.05, 5.97, all P< 0.0 5). Conclusion The BiPAP non-invasive ventilator sequential ventilation for the treatment of AECOPD with pulmonary encephalopathy has good treatment effect,which can improve the difficult ventilation of patients,avoid hypoxia and CO2 retention,shorten treatment time. Key words: Ventilators,mechanical; Pulmonary disease,chronic obstructive; Brain diseases

Effect of Minimally Invasive Surfactant Therapy on Lung Volume and Ventilation in Preterm Infants

A growing number of studies have demonstrated the efficacy of high-flow nasal cannula therapy (HFNC) for treating children with acute respiratory distress. However, it remains unknown whether HFNC is effective in bedridden patients with acute respiratory distress. We retrospectively reviewed the medical records of bedridden patients with acute respiratory distress who were treated with HFNC using a home ventilator in continuous positive airway pressure mode at our center between March 2014 and August 2016. We assessed heart rate, respiratory rate, oxygen saturation measured using a pulse oximeter, the partial pressure of venous carbon dioxide, or the transcutaneous partial pressure of carbon dioxide, and symptoms of respiratory distress before and after the initiation of HFNC. During the 2-year-study period, 25 patients were treated with HFNC. The patients' mean heart rate, respiratory rate, oxygen saturation measured using a pulse oximeter, and pressure of venous carbon dioxide/the transcutaneous partial pressure of carbon dioxide values improved significantly (P < 0.05). Symptoms of respiratory distress were considerably ameliorated at 1-3 h after the HFNC initiation, except in two patients. In these two patients, the HFNC was replaced with non-invasive positive pressure ventilation. Non-invasive positive pressure was also required at 16 to 168 h after the initiation of HFNC in five of the 28 episodes in which the patient was initially responsive to HFNC, as the patients' respiratory symptoms gradually deteriorated. Performing HFNC with a home ventilator in continuous positive airway pressure mode is effective at treating bedridden patients with acute respiratory distress. However, it is essential that the HFNC can be switched to non-invasive positive pressure if needed.

Objective To observe the effect of BiPAP non-invasive assisted ventilation on acute exacerbation of chronic obstructive pulmonary disease(AECOPD) with acute left heart failure. Methods From January 2017 to December 2018, 100 AECOPD patients with acute left heart failure admitted to the Central Hospital of Yiwu were randomly divided into observation group and control group according to random number table method, with 50 cases in each group.The control group received routine treatment such as oxygen inhalation, anti-infection, spasmolysis and asthma relief, phlegm resolving, diuresis and cardiotonic therapy.The observation group used BiPAP non-invasive auxiliary ventilation therapy on the basis of routine treatment.The basic vital signs[heart rate(HR), systolic blood pressure(SBP), respiratory rate(RR)] and blood gas analysis[partial pressure of arterial oxygen(PaO2), partial pressure of carbon dioxide(PaCO2), oxygen saturation(SaO2), pH value] before treatment and 48h after treatment were compared between the two groups.The levels of N-terminal pro-brain natriuretic peptide were observed and compared before treatment and 24h, 48h after treatment.The therapeutic effect of the two groups was compared. Results The basic vital signs(HR, SBP, RR) and blood gas analysis (PaO2, PaCO2, SaO2, pH value) of the two groups were improved after treatment, and the improvement degrees of the observation group were better than those of the control group(control group: HR t=12.352, P=0.000; RR t=7.872, P=0.000; SBP t=10.469, P=0.000; observation group: HR t=20.032, P=0.000; RR t=12.319, P=0.000; SBP t=13.911, P=0.000; intergroup comparison after treatment: HR t=6.711, P=0.000; RR t=3.742, P=0.000; SBP t=4.172, P=0.000; the control group: pH t=13.115, P=0.000, SaO2t=3.134, P=0.001; PaO2t=3.812, P=0.000; PaCO2t=5.335, P=0.000; the observation group: pH t=24.980, P=0.000; SaO2t=5.305, P=0.000; PaO2t=7.357, P=0.000; PaCO2t=10.172, P=0.000; intergroup comparison after treatment: pH t=7.394, P=0.000; SaO2t=2.851, P=0.002; PaO2t=3.467, P=0.000; PaCO2t=4.063, P=0.000). The N-terminal pro-brain natriuretic peptide in the observation group decreased significantly after 24 hours of treatment compared with the control group, but the difference was no statistically significant(t=0.996, P=0.161). The N-terminal pro-brain natriuretic peptide levels in the observation group were significantly lower than those in the control group at 48 and 72 hours after treatment(t=6.043, P=0.000; t=12.897, P=0.000). The effective rate in the observation group was 88.00%(44/50), which was higher than 72.00%(36/50) in the control group(χ2=4.000, P=0.046). Conclusion BiPAP noninvasive assisted ventilation can effectively relieve symptoms, lessen the work of respiratory muscles, reduce cardiac load, improve myocardial oxygen supply, improve cardiac function, improve patients' oxygenation, improve hypoxemia and hypercapnia, reduce mortality and improve prognosis of AECOPD patients complicated with acute left heart failure. Key words: Pulmonary disease, chronic obstructive; Ventilators, mechanical; Continuous positive airway pressure; Heart failure; Blood gas analysis; Natriuretic peptide, brain; Prognosis; Comparative effectiveness research

In patients treated with noninvasive ventilation, sleep-related breathing changes can modify patient-ventilator interactions, which could reduce its effectiveness. The aim of this prospective observational study was to determine the impact of sleep/wake state on leaks, upper airway obstructive events, and asynchronies in patients treated by long-term noninvasive ventilation. Stable patients adapted to noninvasive ventilation were considered for nocturnal polysomnography. Unintentional leaks, upper airway obstructive events, and asynchronies were compared between sleep and awake periods. Twenty-eight patients were enrolled. Underlying diagnoses were neuromuscular disease (n = 11), chest wall disease (n = 8), and obesity-hypoventilation (n = 9). Leaks were more frequent in sleep than in awake periods, with a median of 10% (interquartile range [IQR], 0%-75%) vs 1% (IQR, 0%-9%) of time (P < .001), respectively. During sleep, asynchronies with and without associated leak affected 27% of breaths (IQR, 16%-39%) compared with non-leak-related asynchronies that were recorded in 8% (IQR, 3%-25%) of breaths (P < .001). Asynchronies affecting more than 10% of total breaths were more frequent in sleep (25 patients, 89%) than in awake time (8 patients, 29%; P = .25). Eleven patients (39%) presented with 5 or more upper airway obstructive events without reduction in ventilatory drive per hour of sleep. In patients adapted to home noninvasive ventilation, leaks, asynchronies, and upper airway obstructive events are frequent during the night and are concentrated in sleep periods. Asynchronies are often associated with leaks. These findings may have clinical implications considering that in patients with low sleep efficiency respiratory events could be underestimated if sleep is not evaluated. Martí S, Ferré A, Sampol G, etal. Sleep increases leaks and asynchronies during home noninvasive ventilation: a polysomnographic study. J Clin Sleep Med. 2022;18(1):225-233.

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Background: Carbon dioxide pressure (pCO2) can be reliably measured transcutaneously and may be of clinical relevance in COPD. Retention of CO2 and exercise-induced hypercapnia (EIH) has been scarcely studied as disease marker in COPD. The aims of this study were (1) to study pCO2 response during the 6MWT and (2) to compare clinical characteristics amongst patients with and without CO2 retention and those with and without EIH during the 6MWT. Methods: Sixty-two COPD patients (age: 63±8years, FEV1: 33±10%pred) participated in study. Transcutaneous carbon dioxide pressure (tcpCO2) was measured continuously during the 6MWT by the use of SenTec device. Measurements where repeated after 1 week and data from the longest 6MWT were analyzed. Results: Half of the patients (50%) had CO2 retention (ΔtcpCO2 >4mmHg from baseline) while the rest preserved or reduced tcpCO2 levels. Nineteen patients (31%) exhibited EIH (tcpCO2 >45mmHg) during the 6MWT. Physiological characteristics of CO2 retainers were similar with non-retainers but patients with EIH were characterized by higher resting tcpCO2 levels within the normal range, lower inspiratory pressures (Pimax), lower BMI, more severe FEV1 and higher dyspnoea at rest compared to non-EIH. The determinants of pCO2 retention were pre-walk dyspnoea and FEV1 while pre-walk dyspnoea and baseline pCO2 levels were crucial for EIH. Conclusions: The pCO2 response to 6MWT is highly heterogeneous in COPD. CO2 retention is related to more pre-walk dyspnoea and worse FEV1 while EIH is associated with more pre-walk dyspnoea and higher baseline PaCO2 levels. Monitoring of pCO2 changes during 6MWT might help to identify patients who need special attention regarding to EIH.

A capnography and transcutaneous CO2 profile of bariatric patients during early postoperative period after opioid-sparing anesthesia.