Hypercapnia during transcatheter aortic valve replacement under monitored anaesthesia care: a retrospective cohort study

BACKGROUND

Acute intraoperative hypercapnia and respiratory acidosis, which can occur during monitored anaesthesia care (MAC), pose significant cardiopulmonary risks for patients with aortic stenosis undergoing transcatheter aortic valve replacement (TAVR). The goal of the present study is to assess the incidence, risk factors and impact of intraoperative hypercapnia during MAC for patients undergoing transfemoral TAVR.

METHODS

Data was collected retrospectively from the electronic medical record of 201 consecutive patients with available intraoperative arterial blood gas (ABG) data who underwent percutaneous transfemoral TAVR with MAC using propofol and dexmedetomidine. ABGs (pH, arterial partial pressure of carbon dioxide (PaCO2) and arterial partial pressure of oxygen) were performed at the start of each case (baseline), immediately prior to valve deployment (ValveDepl), and on arrival to the postanaesthesia care unit. Data was analysed using Fisher's exact test, unpaired Student's t-test, Wilcoxon rank sum or univariate linear regression as appropriate based on PaCO2 and pH during ValveDepl (PaCO2-ValveDepl, pH-ValveDepl) and change in PaCO2 and pH from baseline to ValveDepl (PaCO2-%increase, pH-%decrease) to determine their association with preoperative demographic data, intraoperative anaesthetic and vasoactive medications and postoperative outcomes.

RESULTS

PaCO2 increased by a mean of 28.4% and was higher than baseline in 91% of patients. Younger age, male sex, increased weight and increased propofol dose contributed to higher PaCO2-ValveDepl and greater PaCO2-%increase. Patients with PaCO2-ValveDepl>60 mm Hg, pH≤7.2 and greater pH-%decrease were more likely to receive vasoactive medications, but perioperative PaCO2 and pH were not associated with adverse postoperative outcomes.

CONCLUSIONS

Transient significant hypercapnia commonly occurs during transfemoral TAVR with deep sedation using propofol and dexmedetomidine. Although the incidence of postoperative outcomes does not appear to be affected by hypercapnia, the need for vasopressors and inotropes is increased. If deep sedation is required for TAVR, hypercapnia and the need for haemodynamic and ventilatory support should be anticipated.

A meta-analysis of the effects of transnasal high-flow oxygen therapy in gastrointestinal endoscopy

Purpose

This study aimed to systematically evaluate the clinical effects of using transnasal high-flow nasal cannula (HFNC) and conventional oxygen therapy (COT) in patients undergoing gastrointestinal endoscopy.

Methods

A comprehensive literature search was conducted from 2004 to April 2024 to collect relevant studies on the application of HFNC in patients undergoing gastrointestinal endoscopy. Multiple Chinese and English databases, including China National Knowledge Infrastructure (CNKI), Wanfang Data, Web of Science, PubMed, and Cochrane Library, were searched systematically for randomized controlled trials (RCTs). Two researchers independently screened the literature, extracted data, and assessed the risk of bias in the included studies. RevMan 5.4 software was utilized for conducting the network meta-analysis.

Results

A total of 12 RCTs involving 3,726 patients were included. Meta-analysis results showed that HFNC reduced the incidence of hypoxemia and improved the minimum oxygen saturation (SpO2) compared with COT [odds ratio (OR) = 0.39, 95% confidence interval (CI): 0.29-0.53], [mean difference (MD) = 4.07, 95% CI: 3.14-5.01], and the difference was statistically significant. However, the baseline SpO2 levels and incidence of hypercapnia were not statistically significantly different between the HFNC and COT groups [MD = -0.21, 95% CI: -0.49-0.07]; [OR = 1.43, 95% CI: 0.95-2.15]. In terms of procedure time, the difference between HFNC and COT was not statistically significant, and subgroup analyses were performed for the different types of studies, with standard deviation in the gastroscopy group (MD = 0.09, 95% CI: -0.07-0.24) and the endoscopic retrograde cholangiopancreatography group (MD = 0.36, 95% CI: -0.50-1.23). The results demonstrated a significant reduction in the adoption of airway interventions in the HFNC group compared to the COT group (OR = 0.16, 95% CI: 0.05-0.53), with a statistically significant difference; this result was consistent with those of the included studies.

Conclusion

The application of HFNC improves the incidence of hypoxemia, enhances oxygenation, and reduces airway interventions during gastrointestinal endoscopy. However, HFNC does not significantly affect baseline SpO2, hypercapnia, or procedure time. The limitations of this study must be acknowledged, and further high-quality studies should be conducted to validate these findings.

Accuracy of Transcutaneous Carbon Dioxide Measurement During Transcatheter Aortic Valve Replacement Under Monitored Anesthesia Care: A Prospective Observational Study

Background Transcutaneous carbon dioxide tension (PtcCO2) measurement is a promising alternative to arterial carbon dioxide tension (PaCO2) measurement. PaCO2 measurement is invasive and intermittent, whereas PtcCO2 measurement is non-invasive and continuous. However, previous studies evaluating PtcCO2measurements did not include patients undergoing transcatheter aortic valve replacement (TAVR), who experience anticipated hemodynamic changes, particularly before and after valve placement. Therefore, we investigated whether PtcCO2 measurement could provide an alternative to PaCO2 measurement during transfemoral TAVR under monitored anesthesia care (MAC) with local anesthesia. Methodology We conducted a prospective observational study. We included all consecutive patients with severe aortic stenosis who were scheduled to undergo a transfemoral TAVR under MAC at our institution from November 1, 2020, to April 30, 2021. During the procedures, PaCO2 and PtcCO2 were concurrently monitored six times as a reference standard and index test, respectively. PtcCO2 was monitored continuously using a non-invasive earlobe sensor. The agreement between PtcCO2 and PaCO2 measurements was assessed using the Bland-Altman method, and the 95% limits of agreement were calculated. Based on previous studies, we determined that 95% limits of agreement of ±6.0 mmHg would be clinically acceptable to define PtcCO2 as an alternative to PaCO2. Results We obtained 88 measurement pairs from 15 patients. The lower and upper 95% limits of agreement between the PtcCO2 and PaCO2 measurements were -4.22 mmHg and 6.56 mmHg, respectively. Conclusions During TAVR under MAC with local anesthesia, PtcCO2 measurement could not provide a viable alternative to PaCO2 measurement to reduce high PaCO2 events. This study focused on comparing intraoperative periods before and after valve implantation. Therefore, further investigation is warranted to assess the impact of various factors, including the prosthetic valve type and the hemodynamic effects of balloon aortic valvuloplasty, on PtcCO2 measurement in TAVR.

Transcutaneous Carbon Dioxide Monitoring More Accurately Detects Hypercapnia than End-Tidal Carbon Dioxide Monitoring during Non-Intubated Video-Assisted Thoracic Surgery: A Retrospective Cohort Study

Transcutaneous carbon dioxide (PtcCO₂) monitoring is known to be effective at estimating the arterial partial pressure of carbon dioxide (PaCO₂) in patients with sedation-induced respiratory depression. We aimed to investigate the accuracy of PtcCO₂ monitoring to measure PaCO₂ and its sensitivity to detect hypercapnia (PaCO₂ > 60 mmHg) compared to nasal end-tidal carbon dioxide (PetCO₂) monitoring during non-intubated video-assisted thoracoscopic surgery (VATS). This retrospective study included patients undergoing non-intubated VATS from December 2019 to May 2021. Datasets of PetCO₂, PtcCO₂, and PaCO₂ measured simultaneously were extracted from patient records. Overall, 111 datasets of CO₂ monitoring during one-lung ventilation (OLV) were collected from 43 patients. PtcCO₂ had higher sensitivity and predictive power for hypercapnia during OLV than PetCO₂ (84.6% vs. 15.4%, p < 0.001; area under the receiver operating characteristic curve; 0.912 vs. 0.776, p = 0.002). Moreover, PtcCO₂ was more in agreement with PaCO₂ than PetCO₂, indicated by a lower bias (bias ± standard deviation; -1.6 ± 6.5 mmHg vs. 14.3 ± 8.4 mmHg, p < 0.001) and narrower limit of agreement (-14.3-11.2 mmHg vs. -2.2-30.7 mmHg). These results suggest that concurrent PtcCO₂ monitoring allows anesthesiologists to provide safer respiratory management for patients undergoing non-intubated VATS.

Strategy to Reduce Hypercapnia in Robot-Assisted Radical Prostatectomy Using Transcutaneous Carbon Dioxide Monitoring: A Prospective Observational Study

Purpose

Monitoring end-tidal carbon dioxide partial pressure (P_ETCO₂) is a noninvasive, continuous method, but its accuracy is reduced by prolonged capnoperitoneum and the steep Trendelenburg position in robot-assisted radical prostatectomy (RARP). Transcutaneous carbon dioxide partial pressure (P_TCCO₂) monitoring, which is not affected by ventilator–perfusion mismatch, has been suggested as a suitable alternative. We compared the agreement of noninvasive measurements with the arterial carbon dioxide partial pressure (PaCO₂) over a long period of capnoperitoneum, and investigated its sensitivity and predictive power for detecting hypercapnia.

Patients and Methods

The patients who underwent RARP were enrolled in this study prospectively. Intraoperative measurements of P_ETCO₂, P_TCCO₂, and PaCO₂ were analyzed. The primary outcome was the agreement of noninvasive monitoring with PaCO₂ during prolonged capnoperitoneum. Bias and precision between noninvasive measurements and PaCO₂ were assessed using Bland–Altman analysis. The bias and mean absolute difference were compared using a two-tailed Wilcoxon signed-rank test for pairs. The secondary outcome was the sensitivity and predictive power for detecting hypercapnia. To assess this, the Yates corrected chi-square test and the area under the receiver operating characteristic curve were used.

Results

The study analyzed 219 datasets from 46 patients. Compared with P_ETCO₂, P_TCCO₂ had lower bias, greater precision, and better agreement with PaCO₂ throughout the RARP. The mean absolute difference in P_ETCO₂ and PaCO₂ was larger than that of P_TCCO₂ and PaCO_2, and continued to exceed the clinically acceptable range of 5 mmHg after 1 hour of capnoperitoneum. The sensitivity during capnoperitoneum and overall predictive power of P_TCCO₂ for detecting hypercapnia were significantly higher than those of P_ETCO₂, suggesting a greater contribution to ventilator adjustment, to treat hypercapnia.

Conclusion

P_TCCO₂ monitoring measured PaCO₂ more accurately than P_ETCO₂ monitoring during RARP requiring prolonged capnoperitoneum and a steep Trendelenburg position. P_TCCO₂ monitoring also provides more sensitive measurements for ventilator adjustment and detects hypercapnia more effectively than P_ETCO₂ monitoring.

High-Flow Nasal Cannula Oxygen in Patients Having Anesthesia for Advanced Esophagogastroduodenoscopy: HIFLOW-ENDO, a Randomized Clinical Trial

BACKGROUND

Over 6 million esophagogastroduodenoscopy (EGD) procedures are performed in the United States each year. Patients having anesthesia for advanced EGD procedures, such as interventional procedures, are at high risk for hypoxemia.

METHODS

Our primary study aim was to evaluate whether high-flow nasal cannula (HFNC) oxygen reduces the incidence of hypoxemia during anesthesia for advanced EGD. Secondarily, we studied whether HFNC oxygen reduces hypercarbia or hypotension. After obtaining written informed consent, adults having anesthesia for advanced EGD, expected to last longer than 15 minutes, were randomly assigned to receive HFNC oxygen or standard nasal cannula (SNC) oxygen. The primary outcome was occurrence of one or more hypoxemia events during anesthesia, defined by arterial oxygen saturation <92% for at least 15 consecutive seconds. Secondary outcomes were occurrence of one or more hypercarbia or hypotension events. A hypercarbia event was defined by a transcutaneous CO2 measurement 20 mm Hg or more above baseline, and a hypotension event was defined by a mean arterial blood pressure measurement 25% or more below baseline.

RESULTS

Two hundred seventy-one adult patients were enrolled and randomized, and 262 patients completed study procedures. Eight randomized patients did not complete study procedures due to changes in their anesthesia or endoscopy plan. One patient was excluded from analysis because their procedure was aborted after 1 minute. Patients who received HFNC oxygen (N = 132) had a significantly lower incidence of hypoxemia than those who received SNC oxygen (N = 130; 21.2% vs 33.1%; hazard ratio [HR] = 0.59 [95% confidence interval {CI}, 0.36-0.95]; P = .03). There was no difference in the incidence of hypercarbia or hypotension between the groups. The HR for hypercarbia with HFNC oxygen was 1.29 (95% CI, 0.89-1.88; P = .17), and the HR for hypotension was 1.25 (95% CI, 0.86-1.82; P = .25).

CONCLUSIONS

HFNC oxygen reduces the incidence of hypoxemia during anesthesia for advanced EGD and may offer an opportunity to enhance patient safety during these procedures.

Prospective Observational Investigation of Capnography and Pulse Oximetry Monitoring After Cesarean Delivery With Intrathecal Morphine

BACKGROUND

Intrathecal morphine provides excellent analgesia after cesarean delivery; however, respiratory events such as apnea, bradypnea, and hypoxemia have been reported. The primary study aim was to estimate the number of apneas per subject, termed "apnea alert events" (AAEs) defined by no breath for 30-120 seconds, using continuous capnography in women who underwent cesarean delivery.

METHODS

We performed a prospective, observational study with institutional review board approval of women who underwent cesarean delivery with spinal anesthesia containing 150-µg intrathecal morphine. A STOP-Bang obstructive sleep apnea assessment was administered to all women. Women were requested to use continuous capnography and pulse oximetry for 24 hours after cesarean delivery. Nasal sampling cannula measured end-tidal carbon dioxide (EtCO2) and respiratory rate (RR), and oxygen saturation (SpO2) as measured by pulse oximetry. Capnography data were defined as "valid" when EtCO2 >10 mm Hg, RR >5 breaths per minute (bpm), SpO2 >70%, or during apnea (AAE) defined as "no breath" (EtCO2, <5 mm Hg) for 30-120 seconds. Individual respiratory variable alerts were 10-second means of EtCO2 <10 mm Hg, RR <8 bpm, and SpO2 <94%. Nurse observations of RR (hourly and blinded to capnography) are reported.

RESULTS

We recruited 80 women, mean (standard deviation [SD]) 35 (5) years, 47% body mass index >30 kg/m2/weight >90 kg, and 11% with suspected obstructive sleep apnea (known or STOP-Bang score >3). The duration of normal capnography and pulse oximetry data was mean (SD) (range) 8:28 (7:51) (0:00-22:32) and 15:08 (6:42) (1:31-23:07) hours:minutes, respectively; 6 women did not use the capnography. There were 198 AAEs, mean (SD) duration 57 (27) seconds experienced by 39/74 (53%) women, median (95% confidence interval for median) (range) 1 (0-1) (0-29) per subject. Observation of RR by nurses was ≥14 bpm at all time-points for all women, r = 0.05 between capnography and nurse RR (95% confidence interval, -0.04 to 0.14). There were no clinically relevant adverse events for any woman. Sixty-five women (82%) had complaints with the capnography device, including itchy nose, nausea, interference with nursing baby, and overall inconvenience.

CONCLUSIONS

We report 198 AAEs detected by capnography among women who underwent cesarean delivery after receiving intrathecal morphine. These apneas were not confirmed by the intermittent hourly nursing observations. Absence of observer verification precludes distinction between real, albeit nonclinically significant alerts with capnography versus false apneas. Discomfort with the nasal sampling cannula and frequent alerts may impact capnography application after cesarean delivery. No clinically relevant adverse events occurred.

Benefits and harms of capnography during procedures involving moderate sedation: A rapid review and meta-analysis

BACKGROUND

Patient safety is a priority in dentistry. Evaluating the benefits and harms associated with the addition of capnography to standard monitoring during moderate sedation for adult patients in the dental practice setting is needed.

TYPES OF STUDIES REVIEWED

The authors used rapid review methodology to identify relevant systematic reviews, which they updated through a systematic search by using the same search strategy as the identified reviews. The authors searched PubMed and Google Scholar and through the references of the identified systematic reviews, which yielded 2,892 studies. Inclusion criteria were that the article was available in English, was original research in adult humans who had undergone moderate procedural sedation, and involved comparing standard monitoring with the addition of capnography.

RESULTS

Sixteen studies were eligible, involving 3,866 adults undergoing procedural sedation. The authors used the Grading of Recommendations Assessment, Development and Evaluation approach to evaluate the evidence and rate it as being of moderate to low quality because of high risk of bias and heterogeneous effects for the outcomes of hypoxemia and adverse respiratory events. Capnography had higher sensitivity to detect adverse respiratory events than did standard monitoring alone (0.92; 95% confidence interval, 0.65 to 0.99) and may reduce the risk of developing hypoxemia by 31% (risk ratio, 0.69; 95% confidence interval, 0.57 to 0.82). Capnography did not affect the risk of developing serious adverse events, procedure time, sedation quality, or patient satisfaction.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Adding capnography to standard monitoring of adults during moderate sedation may reduce the risk of developing hypoxemia, increase detection of adverse respiratory events, and is not associated with additional harms. These findings suggest routine use of capnography during moderate sedation has the potential to reduce adverse anesthetic outcomes in dental practice.

Recent advances in respiratory monitory in nonoperating room anesthesia

PURPOSE OF REVIEW

Sedation for nonoperating room procedures is experiencing a considerable increase in demand. Respiratory compromise is one of the most common adverse events seen in sedation. Capnography is a modality that has been widely adopted in this area, but may not be well suited to the special demands of nonoperating room sedation. This review is an assessment of new technologies that may improve outcomes beyond those achievable with capnography.

RECENT FINDINGS

New devices for detecting the onset of apnea and for assessing respiratory depression have emerged which have advantages over conventional capnography for detecting apnea without excessive false positive and false negative rates. In addition, monitors that assess respiratory drive have become available, and these may prove useful in regulating depth of sedation.

SUMMARY

No single monitor is ideal for all settings. During brief endoscopic sedation, detection of apnea is paramount, while during longer procedures, avoiding excessive respiratory depression is more critical. The clinician must choose the appropriate monitor based on an understanding of the challenges of the particular environment.

Effectiveness of preanesthetic administration of gabapentin on sedative action during intravenous sedation with propofol

PURPOSE

There are no sufficient evidences for the sedative effect of gabapentin during anesthesia, especially intravenous sedation (IVS). The purpose of this study was to evaluate the sedative effect of gabapentin as preanesthetic medication during the IVS with propofol.

METHODS

10 volunteer subjects joined this study. They underwent propofol IVS three times on separate days. On the first day, the IVS without gabapentin was performed as a control. On the second and the third day, gabapentin 200 mg and 400 mg were administered before the IVS, respectively. The target blood concentration (C_T) of propofol was gradually increased, and the bispectral index (BIS) value and Ramsay sedation score (RSS) were evaluated at each propofol C_T. Postanesthetic complications and influences on vital signs were also evaluated.

RESULTS

Compared to the control group, the propofol C_Ts in the gabapentin 400 mg group significantly reduced at the BIS values of 60 and 70 (p = 0.031 and p = 0.043, respectively), and at RSS 3, 4, 5 and 6 (p = 0.040, p = 0.004, p = 0.001 and p = 0.004, respectively). There was no significant difference in propofol C_Ts between the control group and the gabapentin 200 mg group. There were no abnormality and no deterioration in circulation and respiration in all groups. There were no significant increases in complications with the administration of gabapentin.

CONCLUSION

The oral administration of 400 mg dose of gabapentin reduced the propofol C_Ts for achieving an adequate sedation level on IVS.

Transcutaneous Carbon Dioxide Measurements in Women Receiving Intrathecal Morphine for Cesarean Delivery: A Prospective Observational Study

BACKGROUND

Neuraxial morphine is the most commonly used analgesic technique after cesarean delivery. The incidence of respiratory depression is reported to be very low (0%-1.2%) in this patient population as measured by pulse oximetry and respiratory rates. However, hypercapnia may be a more sensitive measure of respiratory depression. In the current study, the incidence of hypercapnia events (transcutaneous CO2 [TcCO2] >50 mm Hg) for ≥2-minute duration was evaluated using the Topological Oscillation Search with Kinematical Analysis monitor in women who received intrathecal morphine for postcesarean delivery analgesia.

METHODS

Healthy women (>37 weeks of gestation) scheduled for a cesarean delivery with spinal anesthesia with intrathecal morphine were recruited. Baseline STOP-BANG sleep apnea questionnaire and TcCO2 readings were obtained. Spinal anesthesia was initiated with 12 mg hyperbaric bupivacaine, 15 µg fentanyl, and 150 µg morphine. The Topological Oscillation Search with Kinematical Analysis monitor was reapplied in the postanesthesia care unit and TcCO2 measurements obtained for up to 24 hours. Supplemental opioid administration and adverse respiratory events were recorded. The primary outcome was the incidence of hypercapnia events, defined as a TcCO2 reading >50 mm Hg for ≥2 minutes in the first 24 hours after delivery.

RESULTS

Of the 120 women who were recruited, 108 completed the study. Thirty-five women (32%; 99.15% confidence interval, 21%-45%) reached the primary outcome of a sustained hypercapnia event. The median time (interquartile range [IQR]) from intrathecal morphine administration to the hypercapnia event was 300 (124-691) minutes. The median (IQR) number of events was 3 (1-6) and longest duration of an event was 25.6 (8.4-98.7) minutes. Baseline median (IQR) TcCO2 measurements were 35 (30-0) mm Hg and postoperatively, median (IQR) TcCO2 measurements were 40 (36-43) mm Hg, a difference of 5 mm Hg (99.15% confidence interval of the difference 2-8 mm Hg, P < .001). The incidence of hypercapnia events was 5.4% in women with a baseline TcCO2 value ≤31 mm Hg, 22.5% with a baseline TcCO2 between 32 and 38 mm Hg, and 77.4% with a baseline TcCO2 >38 mm Hg (P < .001).

CONCLUSIONS

Hypercapnia events (>50 mm Hg for ≥2-minute duration) occurred frequently in women receiving 150 μg intrathecal morphine for postcesarean analgesia. Higher baseline TcCO2 readings were observed in women who had hypercapnia events.

Extended Monitoring during Endoscopy

Gastrointestinal endoscopic sedation has improved procedural and patient outcomes but is associated with attendant risks of oversedation and hemodynamic compromise. Therefore, close monitoring during endoscopic procedures using sedation is critical. This monitoring begins with appropriate staff trained in visual assessment of patients and analysis of basic physiologic parameters. It also mandates an array of devices widely used in practice to evaluate hemodynamics, oxygenation, ventilation, and depth of sedation. The authors review the evidence behind monitoring practices and current society recommendations and discuss forthcoming technologies and techniques that are poised to improve noninvasive monitoring of patients under endoscopic sedation.

Noninvasive Measurement of Carbon Dioxide during One-Lung Ventilation with Low Tidal Volume for Two Hours: End-Tidal versus Transcutaneous Techniques

BACKGROUND

There may be significant difference between measurement of end-tidal carbon dioxide partial pressure (PetCO2) and arterial carbon dioxide partial pressure (PaCO2) during one-lung ventilation with low tidal volume for thoracic surgeries. Transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring can be used continuously to evaluate PaCO2 in a noninvasive fashion. In this study, we compared the accuracy between PetCO2 and PtcCO2 in predicting PaCO2 during prolonged one-lung ventilation with low tidal volume for thoracic surgeries.

METHODS

Eighteen adult patients who underwent thoracic surgeries with one-lung ventilation longer than two hours were included in this study. Their PetCO2, PtcCO2, and PaCO2 values were collected at five time points before and during one-lung ventilation. Agreement among measures was evaluated by Bland-Altman analysis.

RESULTS

Ninety sample sets were obtained. The bias and precision when PtcCO2 and PaCO2 were compared were 4.1 ± 6.5 mmHg during two-lung ventilation and 2.9 ± 6.1 mmHg during one-lung ventilation. Those when PetCO2 and PaCO2 were compared were -11.8 ± 6.4 mmHg during two-lung ventilation and -11.8 ± 4.9 mmHg during one-lung ventilation. The differences between PtcCO2 and PaCO2 were significantly lower than those between PetCO2 and PaCO2 at all five time-points (p < 0.05).

CONCLUSIONS

PtcCO2 monitoring was more accurate for predicting PaCO2 levels during prolonged one-lung ventilation with low tidal volume for patients undergoing thoracic surgeries.

The effect of ketamine on hypoventilation during deep sedation with midazolam and propofol: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Hypoventilation is a major cause of morbidity and mortality in patients having procedures under sedation. Few clinical strategies have been evaluated to reduce intraoperative hypoventilation during surgical procedures under deep sedation.

OBJECTIVE

The primary objective of this investigation was to examine the effect of ketamine on hypoventilation in patients receiving deep sedation for surgery with midazolam and propofol.

DESIGN

The study was a randomised, placebo-controlled, double-blind clinical trial.

SETTING

Intraoperative.

PATIENTS

Healthy women undergoing breast surgery.

INTERVENTION

Randomised to receive ketamine (0.5 mg kg bolus, followed by an infusion of 1.5 μg kg min) or isotonic saline.

MAIN OUTCOME MEASURE

Duration of hypercapnia measured continuously with a transcutaneous carbon dioxide (TCO2) monitor.

RESULTS

Fifty-four participants were recruited. Patient and surgical characteristics were similar between the study groups. The median percentage of the sedation time with TCO2 more than 6.7 kPa in participants in the ketamine group, 1.2% (95% confidence interval, CI, 0 to 83), was less than that in the isotonic saline group (65%, 95% CI, 0 to 88; P = 0.01). Severe hypoventilation (TCO2 >8.0 kPa) was also less in the ketamine group, median 0% (95% CI, 0 to 11.7) compared with 28% (95% CI, 0 to 79.3; P = 0.0002) for the isotonic saline group. The ketamine group required less airway manoeuvres (chin lift) to keep the SaO2 greater than 95% median (95% CI) [0 (0 to 3) compared with 3 (0 to 16) in the isotonic saline group] (P = 0.004).

CONCLUSION

Ketamine decreased the duration and severity of hypercapnia in patients undergoing deep sedation with propofol. The addition of ketamine may reduce hypoventilation and adverse effects in patients having procedures under sedation.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT01535976.

Evaluation of a transcutaneous carbon dioxide monitor in patients with acute respiratory failure

BACKGROUND

Non-invasive measurement of oxygenation is a routine procedure in clinical practice, but transcutaneous monitoring of PCO(2)(PtCO(2)) is used much less than expected.

METHODS

The aim of our study was to analyze the value of a commercially available combined SpO(2)/PtCO(2) monitor (TOSCA-Linde Medical System, Basel, Switzerland) in adult non-invasive ventilated patients with acute respiratory failure. Eighty critically ill adult patients, requiring arterial blood sample gas analyses, underwent SpO(2) and PtCO(2) measurements (10 min after the probe was attached to an earlobe) simultaneously with arterial blood sampling. The level of agreement between PaCO(2) - PtCO(2) and SaO(2) - SpO(2)was assessed by Bland-Altman analyses.

RESULTS

Both, SaO(2) from blood gas analysis and SpO(2) from the transcutaneous monitor, and PaCO(2) and PtCO(2) were equally useful. No measurements were outside of the acceptable clinical range of agreement of ± 7.5 mmHg.

CONCLUSIONS

The accuracy of estimation of the TOSCA transcutaneous electrode (compared with the "gold standard" blood sample gas analysis) was generally good. Moreover, TOSCA presents the advantage of the possibility of continuous non-invasive measurement. The level of agreement of the two methods of measurement allows us to state that the TOSCA sensor is useful in routine monitoring of adults admitted to an intermediate respiratory unit and undergoing non-invasive ventilation.

Use of a combined SpO₂/PtcCO₂ sensor in the delivery room

Arterial oxygen saturation (SaO₂) and partial arterial pressure of carbon dioxide (PaCO₂) are important respiratory parameters in critically ill neonates. A sensor combining a pulse oximeter with the Stow-Severinghaus electrode, required for the measurement of peripheral oxygen saturation (SpO₂) and transcutaneous partial pressure of carbon dioxide (PtcCO₂), respectively, has been recently used in neonatal clinical practice (TOSCA^500ÒRadiometer). We evaluated TOSCA usability and reliability in the delivery room (DR), throughout three different periods, on term, late-preterm, and preterm neonates. During the first period (period A), 30 healthy term neonates were simultaneously monitored with both TOSCA and a MASIMO pulse oximeter. During the second period (period B), 10 healthy late-preterm neonates were monitored with both TOSCA and a transcutaneous device measuring PtcCO₂ (TINA^Ò TCM3, Radiometer). During the third period (period C), 15 preterm neonates were monitored with TOSCA and MASIMO after birth, during stabilization, and during transport to the neonatal intensive care unit (NICU). Blood gas analyses were performed to compare transcutaneous and blood gas values. TOSCA resulted easily and safely usable in the DR, allowing reliable noninvasive SaO₂ estimation. Since PtcCO₂ measurements with TOSCA required at least 10 min to be stable and reliable, this parameter was not useful during the early resuscitation immediately after birth. Moreover, PtcCO₂ levels were less precise if compared to the conventional transcutaneous monitoring. However, PtcCO₂ measurement by TOSCA was useful as trend-monitoring after stabilization and during transport to NICU.

Recent advance in patient monitoring

Recent advance in technology has developed a lot of new aspects of clinical monitoring. We can monitor sedation levels during anesthesia using various electroencephalographic (EEG) indices, while it is still not useful for anesthesia depth monitoring. Some attempts are made to monitor the changes in sympathetic nerve activity as one of the indicators of stress, pain/analgesia, or anesthesia. To know the balance of sympathetic and parasympathetic activity, heart rate or blood pressure variability is investigated. For trend of cardiac output, low invasive monitors have been investigated. Improvement of ultrasound enables us to see cardiac structure and function continuously and clearer, increases success rate and decreases complication of central venous puncture and various kinds of nerve blocks. Without inserting an arterial catheter, trends of arterial oxygen tension or carbon dioxide tension can be monitored. Indirect visualization of the airway decreases difficult intubation and makes it easier to teach tracheal intubation. The changes in blood volume can be speculated non-invasively. Cerebral perfusion and metabolism are not ordinary monitored yet, but some studies show their usefulness in management of critically ill. This review introduces recent advances in various monitors used in anesthesia and critical care including some studies of the author, especially focused on EEG and cardiac output. However, the most important is that these new monitors are not almighty but should be used adequately in a limited situation where their meaning is confirmed.