A survey of current usage of anticholinergic drugs in paediatric anaesthesia in Finland

BACKGROUND: The aim of this survey was to obtain information about the current use of anticholinergic preanaesthetic medication in children. It was carried out as a follow-up study of the previous survey amongst Finnish anaesthesiologists in 1990. METHODS: A questionnaire was send to all members of the Finnish Society of Anaesthesiologists. Data from anaesthesiologists taking care of at least three paediatric anaesthesias/week (n= 183) were analyzed. RESULTS: In 1998 only one-third of the Finnish anaesthesiologists routinely used anticholinergics before paediatric anaesthesia. The main indications for routine anticholinergic premedication were ENT surgery (66%), eye surgery (71%) and endoscopic procedures (67%). Anticholinergic drugs were administered principally via the intravenous route (90%) briefly before induction of anaesthesia, and glycopyrrolate was the most frequently used (66%). CONCLUSION: During the last eight years in Finland the routine use of anticholinergic premedication has decreased. As in 1990 the anticholinergic prophylaxis is directed to ENT and eye surgery, endoscopic procedures and to children younger than 1 year. Use of glycopyrrolate has gained popularity at the expense of atropine and scopolamine.     

Learning insertion of a Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) catheter: Is clinical experience necessary? A prospective trial

BackgroundResuscitative endovascular balloon occlusion of the aorta (REBOA) is an emerging and potentially life-saving procedure, necessitating qualified operators in an increasing number of centres. The procedure shares technical elements with other vascular access procedures using the Seldinger technique, which is mastered by doctors not only in endovascular specialties but also in trauma surgery, emergency medicine, and anaesthesiology. We hypothesised that doctors mastering the Seldinger technique (experienced anaesthesiologist) would learn the technical aspects of REBOA with limited training and remain technically superior to doctors unfamiliar with the Seldinger technique (novice residents) given similar training.MethodsThis was a prospective trial of an educational intervention. Three groups of doctors were enroled: novice residents, experienced anaesthesiologists, and endovascular experts. The novices and the anaesthesiologists completed 2.5 h of simulation-based REBOA training. Their skills were tested before and 8–12 weeks after training using a standardised simulated scenario. The endovascular experts, constituting a reference group, were equivalently tested. All performances were video recorded and rated by three blinded experts using a validated assessment tool for REBOA (REBOA-RATE). Performances were compared between groups and with a previously published pass/fail cutoff.ResultsSixteen novices, 13 board-certified specialists in anaesthesiology, and 13 endovascular experts participated. Before training, the anaesthesiologists outperformed the novices by 30 percentage points of the maximum REBOA-RATE score (56% (SD 14.0) vs 26% (SD 17%), p<0.01). After training, there was no difference in skills between the two groups (78% (SD 11%) vs 78 (SD 14%), p = 0.93). Neither group reached the endovascular experts' skill level (89% (SD 7%), p<0.05).ConclusionFor doctors mastering the Seldinger technique, there was an initial inter-procedural transfer of skills advantage when performing REBOA. However, after identical simulation-based training, novices performed equally well to anaesthesiologists, indicating that vascular access experience is not a prerequisite to learning the technical aspects of REBOA. Both groups would need more training to reach technical proficiency.     

Standard preoxygenation technique versus two rapid techniques in pregnant patients

The aim of this study was to compare three different preoxygenation techniques in pregnant women by measuring end-tidal fractional oxygen concentration (FETO2): the traditional technique of 3min tidal volume breathing (VT x 3 min), 8 deep breaths (8 DB) and 4 deep breaths (4 DB). Twenty pregnant volunteers without pulmonary diseases were studied during the third trimester (36-38 weeks' gestation). Women were preoxygentated using a non-rebreathing respiratory circuit with a 3-L reservoir bag and a Capnomac Ultima calibrated before each patient to monitor FETO2 continuously. The three preoxygenation techniques were investigated in random order: VT x 3 min using an oxygen flow of 9 L min-1, 4 DB within 30s using an oxygen flow of 9 L min-1, and 8 DB within one minute using an oxygen flow of 15 L min-1. Between each technique, 5-min room air breathing was allowed to return to baseline FETO2 assessed by the Capnomac Ultima. An FETO2 >/= 90% was achieved more frequently with the VT x 3 min and the 8 DB techniques (76%) than with the 4 DB technique (18%) (P < 0.05). The average time required for obtaining an FETO2 >/= 90% was 107+/-37s. Both the VT x 3 min and the 8 DB techniques are therefore more effective for preoxygenation in pregnant patients than the 4 DB technique. In an acute obstetric emergency before rapid-sequence induction of general anaesthesia, 8 DB preoxygenation technique could be recommended.     

Optimizing preoxygenation in adults

Purpose

Preoxygenation increases oxygen reserves and duration of apnea without desaturation (DAWD), thus it provides valuable additional time to secure the airway. The purpose of this Continuing Professional Development (CPD) module is to examine the various preoxygenation techniques that have been proposed and to assess their effectiveness in healthy adults and in obese, pregnant, and elderly patients.

Principal findings

The effectiveness of preoxygenation techniques can be evaluated by measuring DAWD, i.e., the time for oxygen saturation to decrease to <90%. Clinically, preoxygenation is considered adequate when end-tidal oxygen fraction is >90%. This is usually achieved with a 3-min tidal volume breathing (TVB) technique. As a rule, asking the patient to take four deep breaths in 30 sec (4 DB 30 sec) yields poorer results. Eight deep breaths in 60 sec (8 DB 60 sec) is equivalent to TVB 3 min. The DAWD is decreased in obese patients, pregnant women, and patients with increased metabolism. Obese patients may benefit from the head-up position and positive pressure breathing. A TVB technique is preferable in the elderly. Failure to preoxygenate is often due to leaks, which commonly occur in edentulous or bearded patients. In cases of difficult preoxygenation, directly applying the circuit to the mouth might be a useful alternative. Supplying extra oxygen in the nasopharynx during apnea might increase DAWD.

Conclusion

Since ventilation and tracheal intubation difficulties are unpredictable, this CPD module recommends that all patients be preoxygenated. The TVB 3 min and the 8 DB 60 sec techniques are suitable for most patients; however, the 4 DB 30 sec is inadequate.     

Monitoring expired oxygen fraction in preoxygenation of patients with chronic obstructive pulmonary disease

OBJECTIVES: To compare the rate of preoxygenation before induction of anesthesia in patients with no lung disease and in patients with chronic obstructive pulmonary disease (COPD). PATIENTS AND METHODS: End-tidal fractional oxygen concentration (FEO2) was monitored using a paramagnetic oxygen analyzer, during a 5 minute-period of preoxygenation (tidal breathing of 100% oxygen) in 16 control patients (control group) and in 15 patients with COPD. COPD was defined and its severity was characterized by clinical criteria and by respiratory functional tests. FEO2 increase was compared between groups using Anova. RESULTS: The increase in FEO2 was slower in the COPD group than in control group (p < 0.05). After 2 and 3 minutes of preoxygenation, FEO2 was significantly lower in COPD group as compared to control group, but was not different at 5 minutes. Mean time to reach a FEO2 equal to 0.90 was significantly longer in COPD than in control group (COPD: 261 +/- 130 s; control: 165 +/- 90 s, p < 0.05). SpO2 measured during room air breathing was moderately lower in COPD group, but this difference was no more significant after 30 s of preoxygenation (SpO2 after 30 s: control: 98.8 +/- 1.0%; COPD: 98.2 +/- 1.9%, NS). CONCLUSION: These results suggest that preoxygenation monitoring may be useful in patients with COPD, to ensure adequate preoxygenation is achieved.     

Analysis of chest radiographs of patients with thoracic trauma is not influenced by a grid nor by the experience of the reader

OBJECTIVE: To evaluate the interest of a grid and the experience of the interpreter to interpretate the chest radiographs (CRs) of patients with thoracic trauma, the reference is the helicoidal computed tomography (HCT). STUDY DESIGN: Prospective observational study. MATERIAL: CRs and HCT of 50 thorax trauma patients. METHOD: CRs were analysed without a grid (L) and results were compared with those obtained in an anterior study with a grid (G). The interpreter were residents in anaesthesiology (DESAR; G: n = 6/L: n = 4), residents in radiology (DESR; G: n = 3/L: n = 5), senior anaesthesiologists (MAR; G: n = 5/L: n = 4), and senior radiologists (MR; G: n = 3/L: n = 5). The reference was the HCT. The lectors were compared. RESULTS: The interpretation of the CRs was neither influenced by the experience and the specialty of the lector nor by the use of a grid. Perhaps the formation is sufficient for the anaesthesiologists to evaluate the essential lesions in the trauma patient and treat them.     

Preoxygenation--the importance of a good face mask seal

We have studied 16 healthy volunteers whose lungs were preoxygenated six times each in order to assess the amount of room air entrained during tidal volume preoxygenation if a good seal is not maintained between the face mask and the face. With a fresh gas flow of 10 litre min-1, we found that using gravity alone to hold the face mask in position, more than 20% room air was entrained; if the face mask was held adjacent to the face, more than 40% room air was entrained.      

Post-operative rounds by anaesthesiologists after hip fracture surgery: a pilot study

BACKGROUND: Efforts to optimize the peri-operative care of hip fracture patients through multidisciplinary intervention have focused on orthopaedic-geriatric liaisons, which have not resulted in significant outcome changes. The early phase of rehabilitation could potentially be optimized through a multidisciplinary effort between anaesthesiologists and orthopaedic surgeons. METHODS: During the first 25 weeks of 2004, 98 consecutive community-residing patients admitted to a hip fracture unit received daily rounds by anaesthesiologists during the first four post-operative days, on weekdays only, focusing on all facets of peri-operative care. Two hours were allotted to rounds in the 14-bed unit. One hundred and twenty-six consecutive patients admitted to the unit in 2003, receiving the same well-defined care programme, were chosen as a control group. Outcome measures were morbidity and the need for visits by external specialists. RESULTS: The intervention group received 291 rounds by anaesthesiologists. Active therapeutic interventions were prescribed in 76% of all patient confrontations. The control group received 128 requested visits from internal medicine specialists, which was reduced to 50 in the intervention group (P = 0.02). There was no significant difference between post-operative morbidity and hospital stay in the control and intervention groups; in-hospital mortality was 12% in the control group and 7% in the intervention group (P = 0.24). The rounds by anaesthesiologists improved nursing care conditions. CONCLUSION: This pilot study, with insufficient power to show significant differences in outcome, supports further evaluation of the concept of intensified orthopaedic-anaesthesiological co-operation after hip fracture surgery. Such a randomized trial should evaluate economic and clinical outcome aspects, providing anaesthesiological rounds 7 days per week.     

Clinical practice and routines for day surgery in Sweden: results from a nation-wide survey

Background: Day surgery has expanded considerably during the last decades. Routines and standards have developed but differ between and within countries.
Methods: We studied the practice of day surgery in Sweden by an extensive questionnaire survey sent to all 92 hospitals.
Results: The proportion of day surgery vs. in-hospital procedures was overall 43%, with 43% in adults and 46% in children. Orthopaedic (33%), general (29%) and gynaecological (17%) surgery were the most common ambulatory procedures. Most patients (>90%) underwent pre-operative assessment by an anaesthesiologist. Patient self-assessment questionnaires were common (86%). Risk stratification for post-operative nausea and vomiting was used by 70% of the departments. Anxiolytic pre-medication was uncommon. Most anaesthesiologists (95%) used pre-operative oral analgesics to initiate post-operative analgesia, the most common being paracetamol (95%), NSAIDs (73%) and coxibs (15%). A balanced general anaesthesia technique was preferred. Post-operatively, 93% of the units routinely assessed patients' pain. Analgesic combinations of paracetamol, NSAIDs and weak opioids were used by 94% of the units. Most hospitals (80%) had standardised discharge criteria based on clinical assessment, and many required a patient escort at home for 24 h post-operatively. Assessments of unplanned admission, re-admission and post-operative complications were not performed routinely. Follow-up telephone calls within 1–2 days were performed regularly in about 40% of the units, or in selected patients only (37%). Pain was the most frequent complaint on follow-up.
Conclusions: In Sweden, a high degree of standardised regime for day surgical practice was found. Post-operative pain is the most common complaint after discharge.     

Preoxygenation in children: for how long?

Although preoxygenation has been extensively studied, to our knowledge this is the first study addressing its optimal length in children, who form a high risk group for developing hypoxaemia during induction of anaesthesia. Recommended preoxygenation times in children range between 1 and 4 min, but whether one of these times maintains arterial oxygen saturation (Sao2) at an adequate level for a longer time period is unknown. This study was performed on 11 healthy children, randomly distributed into either Group 1 (1 min of preoxygenation, n = 6) or Group 2 (3 min of preoxygenation, n = 5). Sao2 was measured by pulse oximetry. While the patients were breathing room air, Sao2 was similar in both groups (97%) and rose to 100% after preoxygenation in all patients. After intravenous induction of anaesthesia and muscle relaxation, all patients became apnoeic. The time taken for the Sao2 to decrease to 90% was measured. In Group 1 this occurred in 91 s, whereas Group 2 required 144 s. Thus, a 3-min rather than a 1-min period of preoxygenation would appear to maintain Sao2 at a safe level for a longer time in children.     

Comparison of eight deep breaths and tidal volume breathing preoxygenation techniques in morbid obese patients

OBJECTIVE: To compare two techniques of preoxygenation, eight deep breaths (8DB) and tidal volume breathing in obese patients by measuring end-tidal fractional oxygen concentration (FETO2) and apnea time from 100% of hemoglobin saturation to 95% (T95%). STUDY DESIGN: Prospective randomized study. METHODS: Twenty obese patients (BMI >40 kg/m2) without cardiorespiratory disease nor difficult intubation criteria were randomized into two groups of ten. One group received preoxygenation with eight deep breaths in one minute (8DB) and the other with three minutes tidal volume preoxygenation (3TV) both under FIO2 100%. FETO2 every minute of preoxygenation and T95% were measured. Data were analyzed with Mann and Whitney test. A p <0.05 was considered significant. RESULT: There was no significant difference between the groups regarding FETO2 values [84 +/- 4% (8DB) and 88 +/- 5% (3TV)] and T95% [176 +/- 23 s (8DB) and 181 +/- 35 s (3TV)]. The PETCO2 was significantly inferior in the 8DB group at the end of preoxygenation [PETCO2 =29 +/- 1 mmHg (8DB) and PETCO2 =36 +/- 5 mmHg (3TV)]. CONCLUSION: 8DB and 3TV preoxygenation techniques in morbid obese patients induce similar FETO2 and T95%. However hyperventilation effects in the 8DB group are unknown.     

L'apprentissage des gestes invasifs et de la gestion d'une situation critique pose-t-il des problèmes éthiques en anesthésie–réanimation ?

OBJECTIVE: To provide information on morbidity and ethical questions associated with learning of invasive techniques (tracheal intubation, positioning of central venous or epidural catheters) and management of anaphylactic shock. STUDY DESIGN: Retrospective survey. METHODS: Written questionnaire to 54 anaesthesiologists and 55 residents. RESULTS: Training was primarily performed by residents having a 6 months-experience for general anaesthesia and by more experienced residents for epidural analgesia. Residents observed first two or three procedures performed by seniors, but did not have theoretical lectures in 30 to 50% of cases. Dead bodies or manikins were rarely used. Despite the presence of experienced anaesthesiologists during the first attempts, there was a high morbidity rate which was considered by 22 to 37% of the interviewed anaesthesiologists a loss of benefit for the patients. Despite a high level of coaching, a high morbidity rate was associated with the first attempts. However, only few residents explicitly stated to be concerned by ethical questions. Among anaesthesiologists, who had yet to manage anaphylactic shock, 21 and 35% of them reported that diagnostic and treatment could have been performed faster. Virtual learning was misunderstood but 46% of anaesthesiologist described numerous advantages in using simulator of anaesthesia. CONCLUSION: Despite an apparent morbidity with a loss of benefit, informed consent of the patients were rarely obtained.     

Management and outcome of patients undergoing thoracic surgery in a regional chest medical centre

BACKGROUND AND OBJECTIVE: The main objective of this study was to assess mortality and morbidity after thoracic surgery in a medical centre, without resident chest surgeons and anaesthesiologists, and to determine specific risk factors. METHODS: A prospective cohort study using a local database which includes patients' clinical characteristics, results of preoperative investigations, surgical and anaesthesia data and all postoperative complications was undertaken. Two hundred and seventy-three consecutive patients undergoing thoracic surgery from 1992 to 1999 were studied. The referral chest medical centre was without resident thoracic surgeons or anaesthesiologists; postoperative care was led by local chest physicians according to standardized protocols and in close collaboration with university-based surgeons and anaesthesiologists. RESULTS: The majority of patients had lung cancer (71%) and underwent resection of at least one lobe (62%). Thirty-day mortality rate was 2.2% and one or more complications occurred in 74 patients (27%). Three patients had to be transferred to a university hospital for further treatment. Univariate predictors of complications included age (> 70 years), history of smoking, body mass index, as well as the extent and duration of surgery. After multiple logistic regression analysis, smoking (current or past), prolonged surgery (>120 min) and major lung resection (pneumonectomy or bilobectomy) remained the only independent risk factors. CONCLUSIONS: Overall perioperative mortality and morbidity rates did not exceed those reported from large teaching hospitals. In selected patients, thoracic surgery can be safely performed in a specialized chest medical centre without on-site surgeons and anaesthesiologists.     

Generating a learning curve for penile block in neonates, infants and children: an empirical evaluation of technical skills in novice and experienced anaesthetists

BACKGROUND: Literature concerning learning curves for anaesthesiological procedures in paediatric anaesthesia is rare. The aim of this study was to assess the number of penile blocks needed to guarantee a high success rate in children. METHODS: At a teaching hospital, the technical skills of 29 residents in anaesthesiology who performed penile blocks under the supervision of two staff anaesthesiologists were evaluated during a 12-month period using a standardized self-evaluation questionnaire. At the start of the study period, the residents had no prior experience in paediatric anaesthesia or in performing penile block. All residents entered the paediatric rotation after a minimum of 1-year training in adult general and regional anaesthesia. The blocks were rated using a binary score. For comparison, the success rates of the two supervising staff anaesthesiologists were collected during the same period using the same self-evaluation questionnaire. Statistical analyses were performed by generating individual and institutional learning curves by using the pooled data. The learning curves were calculated with the aid of a least square fit model. A 95% CI were estimated by a Monte Carlo procedure with a bootstrap technique. RESULTS: In a total number of 392 blocks performed, the overall success rate was 92.1%. There was no statistical difference between the success rate of the two staff members (success rate: 96.3%) and the overall success rate of the 29 residents performing a total of 339 blocks. The total success rate for this group was 91.5%. The failure rate for the first 10 blocks performed by the residents was 8.82% (95% CI: 5.0-14.14%), it was 4.12% (95% CI: 1.13-10.22%) for the next 10 blocks and from blocks 21 to 40 it was 6.5% (95% CI: 2.65-12.9%). For blocks 41-60, the failure rate was 4.4% (95% CI 0.54-15.15%). CONCLUSIONS: Penile block in children is easily learned by residents. A steep learning curve was found. The success rate was over 93.5% after more than 40 blocks.     

Anticholinergic premedication in Finland 1988

In order to investigate the present use of anticholinergic drugs in premedication, a questionnaire was sent to Finnish anaesthesiologists. The results indicate that there is significant variation between different parts of the country regarding the usage of these drugs. A decrease in routine use has taken place over the past 5 years. Half of the anaesthesiologists now routinely use anticholinergic drugs in premedication, while 69% were using them 5 years ago. Glycopyrrolate has gained popularity and was the most used drug. Most anaesthesiologists gave the anticholinergic premedication intravenously, briefly before induction.     

Doctor-patient communication in surgery: attitudes and expectations of general surgery patients about the involvement and education of surgical residents.

BACKGROUND: Education is a major function of academic medical centers. At these teaching institutions residents provide a substantial amount of care on medical and surgical services. The attitudes of patients about the training of surgical residents and the impact of residents on patients' perceptions of care in a surgical setting are unknown. STUDY DESIGN: Patients admitted to the gastrointestinal surgery service completed a 30-item survey designed for this study. Patients included in the study underwent operations and had a postoperative inpatient hospital stay. We analyzed patients' answers to determine frequency and correlations among answers. RESULTS: Two hundred patients participated in the study during a 7-month period between July 1999 and January 2000. A majority of patients were comfortable having residents involved in their care (86%) and felt it was important to help educate future surgeons (91%). Most did not feel inconvenienced by being at a teaching hospital (71%) and felt they received extra attention there (74%). Patients were more willing to participate in resident education if they expected to have several physicians involved in their care, felt that they received extra attention, or if the teaching atmosphere did not inconvenience them. Despite the stated willingness of patients to help with surgical resident education, 32% answered that they would not want residents doing any of their operation. CONCLUSIONS: Surgical resident education is well received and considered important by patients. Patient orientation to the resident education process is vital to patients' perceptions of care and may render patients more willing to participate in educational activities.     

Effect of different pre-oxygenation procedures on arterial oxygen status

There are different opinions regarding efficiency, duration, and techniques of preoxygenation. It was the aim of our study to systematically investigate the effectiveness of different preoxygenation methods by means of arterial blood gas parameters (paO2, SaO2, and CaO2). METHODS. After receiving informed consent, 80 patients undergoing coronary bypass grafting (NY-HA II-III, ASA III-IV, mean age 57 years) were randomized in eight groups, each with a different preoxygenation technique (Table 1). During normocapnic preoxygenation (Table 2), the following parameters were compared: duration of preoxygenation (3 vs. 5 min), manner of holding the face mask (tightly fitting vs. one digit away from mouth and nose), and oxygen flow (6 vs. 10 l/min) via anesthesia circuit system. Arterial blood gases were analyzed with a Corning 170 pH/blood gas analyzer and a Corning 2500 CO-oximeter. For statistical analysis Student's t-test was used. P less than or equal to 0.01 was considered to be significant (*). RESULTS. As Fig. 1 shows, the different preoxygenation techniques affected paO2 values differently: oxygen flow had a greater influence than duration of preoxygenation. Most important was the manner of holding the face mask. With a tightly fitting mask, preoxygenation was more effective than with the face mask one digit away from mouth and nose, independent of preoxygenation time and oxygen flow (Table 3). The SaO2 (Fig. 2) increased in the same manner with the different preoxygenation techniques from 94.0% to 97.5% (Table 3); CaO2 (Fig. 3) was influenced in a similar way (16.7 ml/dl to 17.4 ml/dl).(ABSTRACT TRUNCATED AT 250 WORDS)     

Voluntary hyperventilation before a rapid-sequence induction of anesthesia does not decrease postintubation PaCO2.

To prevent hypercapnia, voluntary hyperventilation is recommended for patients with increased intracranial pressure before the induction of general anesthesia. We sought to determine whether this maneuver results in a lower PaCO2 than breathing 3 min of oxygen 100% by face mask (preoxygenation) after intubation. Thirty patients requiring general anesthesia were randomly assigned to breathe either 3 min of oxygen 100% by face mask (Group P) or 1 min of oxygen 100% followed by 2 min of voluntary hyperventilation with oxygen 100% (Group H). All patients received a standard rapid-sequence induction of anesthesia followed by a 90-s period of apnea. Patients were then tracheally intubated and mechanically ventilated. Five arterial blood gas samples were taken: with room air, after preoxygenation or hyperventilation, after 60 and 90 s of apnea, and after tracheal intubation. Voluntary hyperventilation decreased PaCO2 before rapid-sequence induction (hyperventilation, 30.0 +/- 3.5 mm Hg versus preoxygenation, 37.9 +/- 5.2 mm Hg; P < 0.0001), but after 60 s of apnea, both groups had similar PaCO2 (hyperventilation, 36.1 +/- 3.3 mm Hg versus preoxygenation, 35.6 +/- 3.4 mm Hg; P = 0.673), and no benefit was found after intubation (hyperventilation, 40.5 +/- 3.9 mm Hg versus preoxygenation, 41.4 +/- 2.7 mm Hg; P = 0.603). We conclude that voluntary hyperventilation before rapid-sequence induction does not provide protection against potential hypercapnia during intubation. IMPLICATIONS: Voluntary hyperventilation before anesthesia induction is recommended for patients with increased intracranial pressure to prevent hypercapnia. This randomized, prospective study demonstrated that this maneuver does not result in a lower postintubation PaCO2 than standard preoxygenation.     

Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques

To compare the effectiveness of two routinely used methods of preoxygenation in protecting against hypoxia in the elderly, the arterial O2 saturation was measured using an oximeter. Twenty-four elderly patients (greater than or equal to 65 yr) presenting for elective orthopedic surgery were randomly allocated to receive either 3-min or four-maximal-breaths of 100% O2 via a Bain circuit. After preoxygenation, anesthesia was induced, tracheal intubation performed with patients kept apneic, and the endotracheal tube left open to air. The arterial O2 saturation was measured before preoxygenation and continually recorded during desaturation. Although attaining similar arterial O2 saturation values after preoxygenation, patients in the four-maximal-breath group had significantly shorter times (P less than 0.0001) to all levels of desaturation. We suggest that preoxygenation with 3-min breathing of 100% O2 offers more protection against hypoxia due to prolonged apnea after induction of anesthesia in the elderly than does four maximal breaths of 100% O2.     

Non-invasive positive-pressure ventilation with positive end-expiratory pressure counteracts inward air leaks during preoxygenation: a randomised crossover controlled study in healthy volunteers

Background

During preoxygenation, the lack of tight fit between the mask and the patient's face results in inward air leak preventing effective preoxygenation. We hypothesized that non-invasive positive-pressure ventilation and positive end-expiratory pressure (PEEP) could counteract inward air leak.