Does the advantage of transcutaneous oximetry measurements in diabetic foot ulcer apply equally to free flap reconstruction?

BACKGROUND

Transcutaneous oxygen pressure (TcpO₂) is a precise method for determining oxygen perfusion in wounded tissues. The device uses either electrochemical or optical sensors.

AIM

To evaluate the usefulness of TcpO₂ measurements on free flaps (FFs) in diabetic foot ulcers (DFUs).

METHODS

TcpO₂ was measured in 17 patients with DFUs who underwent anterolateral thigh (ALT)-FF surgery and compared with 30 patients with DFU without FF surgery.

RESULTS

Significant differences were observed in the ankle-brachial index; duration of diabetes; and haemoglobin, creatinine, and C-reactive protein levels between the two groups. TcpO₂ values were similar between two groups except on postoperative days 30 and 60 when the values in the ALT-FF group remained < 30 mmHg and did not increase > 50 mmHg.

CONCLUSION

Even if the flap is clinically stable, sympathectomy due to adventitia stripping during anastomosis and arteriovenous shunt progression due to diabetic polyneuropathy could lead to low TcpO₂ values in the ALT-FF owing to its thick fat tissues, which is supported by the slow recovery of the sympathetic tone following FF. Therefore, TcpO₂ measurements in patients with DFU who underwent FF reconstruction may be less accurate than in those who did not.

Association of transcutaneous CO2 with respiratory support: a prospective double blind observational study in children with bronchiolitis and reactive airway disease

The use of clinical scoring to assess for severity of respiratory distress and respiratory failure is challenging due to subjectivity and interrater variability. Transcutaneous Capnography (TcpCO₂) can be used as an objective tool to assess a patient’s ventilatory status. This study was designed to assess for any correlation of continuous monitoring of TcpCO₂ with the respiratory clinical scores and deterioration in children admitted for acute respiratory distress. A prospective observational study over one year on children aged 2 weeks to 5 years admitted with acute respiratory distress or failure secondary to Bronchiolitis and Reactive airway disease was performed. Continuous TcpCO₂ monitoring for upto 48 h was recorded. Investigators, bedside physicians, respiratory therapists, and nurses were blinded from the transcutaneous trends at the time of data collection. Total of 813 TcpCO₂ measurements at standard intervals of 30 min were obtained on 38 subjects. Subjects with abnormal TcpCO₂ (> 45 mmHg) were younger (6.9 ± 5.2 vs. 23.05 ± 17.7 months,) and were more likely to be on higher oxygen flow rate (0.52 L/min/kg vs 0.46 lier/min/kg, p = 0.004) and higher FiO₂ (38.4 vs 33.6, p < 0.001 using heated high flow nasal cannula. No difference was found in bronchiolitis score or PEW score in subjects with normal and abnormal TcpCO₂. A small but statistically significant increase in TcpCO₂ was observed at the escalation of care. Even though odds of escalation of care are higher with abnormal TcpCO₂ (OR 1.92), this difference did not reach statistical significance. pCO₂ can provide additive information for non-invasive clinical monitoring of children requiring varying respiratory support; however, it does not provide predictive value for escalation or de-escalation of care.

Tissue temperature, flux and oxygen of sacral and trochanteric area under pressure of healthy subjects: A quasi-experimental study

AIM

To evaluate the changes that take place in the perfusion, oxygenation and local temperature of the skin of the sacrum and trochanter when subjected to direct pressure for 2 h.

METHODS

Quasi-experimental study in the preclinical phase with healthy subjects acting as their own controls (intrasubject control). The outcome variables were measured with a laser Doppler system (local temperature and oxygenation) and by near-infrared spectroscopy (perfusion). The pressure exerted was measured with a capacitive pressure sensor. No more than one week elapsed between the sacrum and trochanter measurements.

RESULTS

The study sample consisted of 18 persons. The comparative analysis of the fluctuations in the parameters measured on the skin of the trochanters and sacrum, according to the time elapsed, revealed a statistically significant increase in temperature and in the pressure exerted. On the other hand, the changes in capillary blood flow and in SaO2 were not statistically significant.

CONCLUSION

Our study results show that changes found in terms of temperature and pressure should be taking into account when planning personalised repositioning to patients according to biomechanical and biological situations that vary between anatomical areas. In future research, the changes reported could be evaluated in patients with risk factors for the development of pressure ulcers, thus facilitating the introduction of more personalised planning in the care and prevention of these injuries.

Blood Gas Tension and Acidity Level of Caries Exposed Vital Pulps in Primary Molars

OBJECTIVE

The purpose of this study was to determine if gas tension and acidity levels could serve as biomarkers of pulp inflammatory status in primary dentition.

STUDY DESIGN

The present study evaluated acidity level and blood partial pressures of O2 and CO2 collected from vital pulp chambers of 84 primary molars with deep carious lesions encroaching the pulp. Teeth were treated with pulpotomy or pulpectomy based on clinical judgement. Pulpectomy was performed when symptoms of spontaneous pain, difficulty in obtaining hemostasis and/or dark purple blood were present. Using a glass capillary, pulp chamber bleeding was collected and within ten minutes a neonate Astrup test was performed to determine blood gas module pH, pCO2, and pO2.

RESULTS

Eighty-four children with one affected tooth participated in the study (37 girls and 47 boys). Age ranged between 3.5 to 9-years (average: 5.3 years). Seventy-one (84%) were treated with the aid of inhalation analgesia, conscious sedation or general anesthesia. Pulpotomy was performed on 58 teeth (69%). Teeth undergoing pulpectomy revealed significant higher level of CO2 partial pressure (P= 0.002). Acidity level values (pH) were also lower but none significantly in teeth with pulpectomy (P= 0.137).

CONCLUSIONS

Higher pCO2 levels was found in pulps needing pulpectomy.

Anaesthesia for laparoscopic nephrectomy: Does end-tidal carbon dioxide measurement correlate with arterial carbon dioxide measurement?

Background and Aims:

Not many studies have explored the correlation between arterial carbon dioxide tension (PaCO₂) and end-tidal carbon dioxide tension (ETCO₂) in surgeries requiring pneumoperitoneum of more than 1 hour duration with the patient in non-supine position. The aim of our study was to evaluate the correlation of ETCO₂ with PaCO₂ in patients undergoing laparoscopic nephrectomy under general anaesthesia.

Methods:

A descriptive study was performed in thirty patients undergoing laparoscopic nephrectomy from September 2014 to August 2015. The haemodynamic parameters, minute ventilation, PaCO₂ and ETCO₂ measured at three predetermined points during the procedure were analysed. Correlation was checked using Pearson's Correlation Coefficient Test. P <0.05 was considered statistically significant.

Results:

Statistical analysis of the values showed a positive correlation between ETCO₂ and PaCO₂ (P < 0.05). Following carbon dioxide insufflation, both ETCO₂ and PaCO₂ increased by 5.4 and 6.63 mmHg, respectively, at the end of the 1^st hour. The PaCO₂-ETCO₂ gradient was found to increase during the 1^st hour following insufflation (4.07 ± 2.05 mmHg); it returned to the pre-insufflation values in another hour (2.93 ± 1.43 mmHg).

Conclusion:

Continuous ETCO₂ monitoring is a reliable indicator of the trend in arterial CO₂ fluctuations in the American Society of Anesthesiologists Grades 1 and 2 patients undergoing laparoscopic nephrectomy under general anaesthesia.

24-Hour Hypoxia and Pulmonary Hypertension in Patients with Idiopathic Pulmonary Fibrosis

Background:

The quantification of hypoxia based on resting partial pressure of arterial oxygen (PaO₂) may underestimate hypoxia related to activities of daily living or sleep and thus not accurately reflect pulmonary hypertension (PH). The aim of the present study was to investigate the association of resting PaO₂ with percent time of SpO₂ below 90% (T90) and 88% (T88) in 24 hours. We also evaluated the capacity of hypoxia measures to predict PH in patients with idiopathic pulmonary fibrosis (IPF).

Method:

This cross-sectional study included 27 patients with IPF presenting PaO₂ ≥ 55 mmHg and not receiving home oxygen therapy. All were submitted to blood gas measurement, 24-h oximetry, and transthoracic Doppler echocardiography to estimate systolic pulmonary artery pressure (SPAP). Patients were divided into three groups according to resting PaO₂: 55-55.9 mmHg (A); 60-60.9 mmHg (B); ≥ 70 mmHg (C). PH was defined as “likely” if SPAP > 50 mmHg, and as possible for SPAP between 37 and 50 mmHg.

Results:

T90 and T88 in Groups A, B, and C were as follows: 59.9±29% and 44.1±34%; 49.3±34% and 29.9±31%; 17.1±25% and 8.8±18% respectively, with significant differences between the groups for both T90 (p ≤ 0.01) and T88 (p = 0.02). PaO₂ was inversely correlated with T90 (r = -0.398; p = 0.04) and T88 (r = -0.351; p = 0.07). Hypoxia variables did not correlate with SPAP, and were not able to predict PH.

Conclusion:

Percent time of SpO₂ below 90% and 88% in 24 hours revealed periods of severe hypoxia even in patients with borderline-normal resting PaO₂. However, none of the present hypoxia variables was capable of predicting PH.

Carbon dioxide accumulation during analgosedated colonoscopy: Comparison of propofol and midazolam

AIM: To characterize the profiles of alveolar hypoventilation during colonoscopies performed under sedoanalgesia with a combination of alfentanil and either midazolam or propofol.

METHODS: Consecutive patients undergoing routine colonoscopy were randomly assigned to sedation with either propofol or midazolam in an open-labeled design using a titration scheme. All patients received 4 μg/kg per body weight alfentanil for analgesia and 3 L of supplemental oxygen. Oxygen saturation (SpO₂) was measured by pulse oximetry (POX), and capnography (PcCO₂) was continuously measured using a combined dedicated sensor at the ear lobe. Instances of apnea resulting in measures such as stimulation of the patient, a chin lift, a mask maneuver, or withholding of sedation were recorded. PcCO₂ values (as a parameter of sedation-induced hypoventilation) were compared between groups at the following distinct time points: baseline, maximal rise, termination of the procedure and 5 min after termination of the procedure. The number of patients in both study groups who regained baseline PcCO₂ values (± 1.5 mmHg) five minutes after the procedure was determined.

RESULTS: A total of 97 patients entered this study. The data from 14 patients were subsequently excluded for clinical procedure-related reasons or for technical problems. Therefore, 83 patients (mean age 62 ± 13 years) were successfully randomized to receive propofol (n = 42) or midazolam (n = 41) for sedation. Most of the patients were classified as American Society of Anesthesiologists (ASA) II [16 (38%) in the midazolam group and 15 (32%) in the propofol group] and ASA III [14 (33%) and 13 (32%) in the midazolam and propofol groups, respectively]. A mean dose of 5 (4-7) mg of IV midazolam and 131 (70-260) mg of IV propofol was used during the procedure in the corresponding study arms. The mean SpO₂ at baseline (%) was 99 ± 1 for the midazolam group and 99 ± 1 for the propofol group. No cases of hypoxemia (SpO₂ < 85%) or apnea were recorded. However, an increase in PcCO₂ that indicated alveolar hypoventilation occurred in both groups after administration of the first drug and was not detected with pulse oximetry alone. The mean interval between the initiation of sedation and the time when the PcCO₂ value increased to more than 2 mmHg was 2.8 ± 1.3 min for midazolam and 2.8 ± 1.1 min for propofol. The mean maximal rise was similar for both drugs: 8.6 ± 3.7 mmHg for midazolam and 7.4 ± 3.2 mmHg for propofol. Five minutes after the end of the procedure, the mean difference from the baseline values was significantly lower for the propofol treatment compared with midazolam (0.9 ± 3.0 mmHg vs 4.3 ± 3.7 mmHg, P = 0.0000169), and significantly more patients in the propofol group had regained their baseline value ± 1.5 mmHg (32 of 41 vs 12 of 42, P = 0.0004).

CONCLUSION: A significantly higher number of patients sedated with propofol had normalized PcCO₂ values five minutes after sedation when compared with patients sedated with midazolam.