Last weekend on call I had three sections during the night. The first case was a young nurse, healthy with excellent anatomy for placing a spinal anesthetic. She was admitted around 4pm and went to c-section at 10:00pm for lates and variables.
I performed a spinal in my usual fashion. The hospital supplies us with Spinocan spinal trays. These contain a 25 G spinocan needle, 2 mL of 0.75% hyperbaric bupivacaine, Lidocaine 1% 5 cc and a 3 cc syringe plus a 5 cc syringe for drawing the intrathecal dose. I also administer 12 mg bupivacaine mixed with 20 mcg of fentanyl + 150 mcg of preservative free morphine (duramorph). I also, always grab a 25 G whitacre needle from the anesthesia cart to decrease the risk of PDPH.
I finished this case at 11:15pm and went to bed. At 12:30am I was called by the obstetrician who told me she had a drop in patient with severe PIH. She planned on delivering her, but she her platelets went from 88K to 84K. She wanted to know what I thought. I told her I would place a spinal in this patient as long as the platelets were greater than 75K. We rolled back to the OR at 2:10am and finished at 3:30am. In this patient, due to challenging anatomy (obese patient with lots of adiposity in the lumbar back), I was unable to get the spinal needle (once again a spinocan) into the space with just 2 to 3 attempts. Due to the relative urgency of the case, I opted to use a touhy needle (18G) to locate the midline and use a gertie marx 26G spinal needle through the touhy to inject my usual mix. With the touhy, I rapidly (with one pass) identified the midline and epidural space, inserted the spinal needle, and got a great spinal. The case went smoothly, and blood pressures after spinal normalized almost immediately with no further issues.
At 5:30am, I was called for an urgent c-section. A young healthy patient who was schedule for c-section that very morning but at 10:00am had arrived to the hospital early contracting. She had been scheduled because she was carrying twins who were breech. Because of the urgency, the obstetrician was standing at my side during the spinal placement. I noticed that her anatomy was also very poor for easy identification of the midline. She was obese, with the vast majority of her adipose tissue located in the lumbar region. Palpation of a midline area was very challenging. The patient was also in terrible pain due to near constant uterine contractions and had trouble sitting and holding her position. I elected to immediately start with a tuohy needle as I sensed that I might again have a difficult time identifying the midline by feel with a thin 25G spinal needle. I inserted the touhy needle to a moderate depth without feeling any resistance that I could identify as ligament or bone. No sooner had I got the touhy to a moderate depth (approximately 4.5 cm) did I notice a flash of clear liquid at the hub. I feared a wet tap, so I removed the stylet from the touhy, without any CSF flow. It was clear that there was however some residual clear liquid in the touhy. I removed the touhy and retried with no luck. After searching a minute or two for the midline, I again noticed a small flash of clear liquid in the hub and withdrew the stylet. This time clear fluid drained from the tuohy. While disappointed in this result, my only real option at this time was to inject the spinal cocktail I had prepared. I attached my syringe, aspirated to verify continued CSF drainage, and once this was verified, I injected the anesthetic (12 mg bupivacaine, 20 mpg fentanyl, 150 mpg duramorph). The patient laid down, and very slowly the contractions eased, but did not go away completely. Very quickly it was evident, that the patient did not develop a proper spinal block. GETA via rapid sequence was rapidly induced and the twins were delivered without incident. We finished at 7:05am, the end of my shift.
Case 1 breakdown- discussion of spinocan vs other needle types.
This case went as uneventful as you might expect in a healthy 28 year old female having her 2nd child for NRFHT. The only difference in this cases was that I was forced to use a spinocan needle (cutting type tip) rather than my usual choice of a whitacre. This case was performed at 10PM. I visited the patient on POD 2 at about 4:30pm. She was complaining of a headache which started mid morning on POD 1. It was gone in the morning of POD 2 after a good nights sleep, but returned with a vengeance by early afternoon. It was totally relieved by lying down, and clearly aggravated when the head was elevated.
Modifiable risk factors of PDPH include the needle size, needle shape, bevel orientation and inserting angle, stylet replacement, and operator experience. Needle size might be the most significant factor in the development of PDPH. In our hospital, we only have access to 25G needles. A previous meta-analysis published in 2000 has compared the frequency of PDPH between Quincke (a cutting-point spinal needle) and pencil-point spinal needles which suggested that pencil-point spinal needle will significantly reduce PDPH rate compared with Quincke spinal needles. They found a RR of PDPH of 0.38 if a pencil point needle was used. Criticism of this meta analysis related to its small size (only 15 PDPH occurred in the study), and only two needle types compared (Quincke vs whitacre). One study estimated that the incidence of PDPH when a 25 G cutting needle is used (Quincke) is about 23%  but may be less than 2% if a 27G needle is used. However, a more recent study  a prospective comparison of 5 needle types showed that PDPH went from an incidence of 8% in the quincke style needle to 3% with a whitacre. The requirement for blood patch in this study went from 12.5% with a 25G quincke to 0% with a whitacre. Studies also find that there is less chance of successful spinal anesthesia when smaller gauge needles are used, therefore, the law of diminishing returns becomes significantly apparent with needles smaller than 27G. In a recent meta analysis looking at over six thousands patients, an overall incidence of 4.6% was found for PDPH . The incidence of PDPH was 6.6% for cutting type needles, and 2.6% for pencil point styled needles. This resulted in a RR of PDPH of 2.5 when a cutting style needle was used based on the studies included in this meta analysis.
Other risk factors for PDPH include female sex, younger age, and pre existing headache. Pregnancy may be yet another risk factor for developing PDPH. Ironically, it is this patient population that is most exposed to dural puncture. In this case, the patient suffered a PDPH likely avoided if a pencil point styled needle was used. She was treated with a blood patch on POD 2, and her headache was relieved.
Case 2 breakdown- low plateles requiring urgent delivery due to sever PIH
For a general review on PIH and anesthesia click here. There is no evidence to support any arbitrary cut off when performing neuraxial anesthesia in a patient whose platelets are low (i.e. less than 150k). However, we have indirect evidence that there is some risk associated with neuraxial anesthsia in thrombocytopenic patients. In PIH about 30% of patients will develop thrombocytopenia. The cause is unknown, but damage to the endothelium has been implicated. This is known to cause the release of thromboxane and serotonin from activated platelets and a platelet consumption cascade ensues. As an anesthesia resident, I was taught that below 100k platelets, neuraxial anesthesia is contraindicated in PIH. However, practice patterns are changing. In a small retrospective study of 30 parturients, epidural anesthesia was conducted when platelets were between 69K and 98K . in 1989, Rasmus et al.  found 14 parturients who received neuraxial anesthesia with platelet counts ranging from 15K to 99K. No reports of epidural hematoma were found in this review. In a more recent review Goodier et al.  looked at 174 parturients with low platelet count (less than 100K) and neuraxial anesthesia and found no cases of hematoma formation. Nevertheless, at this time, the numbers of patients documented to have neuraxial anesthesia with platelets less than 100k (~499) is small. In a review by Vandermuelen et al revealed that in cases of epidural hematoma, 75% were in patients who had EA instead of SAB. This rare condition may still be a relevant concern given that it may lead to permanent paraplegia. In the past, many have advocated for epidural anesthesia in PIH or severe PIH for Cesarean delivery to avoid severe hypotension by using a gradual block onset. This is related to the fact that in PIH, intervillous blood flow is decreased, therefore, making these patients particularly vulnerable to hypotension. However, in clinical practice this has not born out. Dyer at al stated that current evidence suggests that parturients with PIH have less susceptibility to hypotension and perhaps less impairment of cardiac output vs their healthy counterparts . In a recent prospective study, hypotension was more frequent in SAB vs. EA for C-section, however, the duration of hypotension was short (less than 1 min) in both groups. Also, hypotension was easily treated in both groups, and the study concluded that SAB was safe for C-section in patients with severe pre eclampsia . In severe PIH, a major concern for maternal health is the avoiding severe hypertension that can result in cerebral bleeding. Ramanathan et al. showed that neuraxial anesthesia is superior to GA in avoiding hypertension during cesarean delivery . Therefore, in patients with severe PIH and low platelets requiring urgent cesarean delivery, SAB is better than EA is probably better than GA.
Case 3 breakdown:
This case was FUBAR. Some of the issues making this case difficult, included: a patient in near hysterics due to near constant contractions, significant obesity located to the lower back area, and the fact that I was exhausted by this point having been working on and off for the last 24 hours. Nevertheless, my decision to use a touhy needle (a routine for me) as my first attempt in a difficult spinal was a problem. It lead to an immediate dural puncture. Unfortunately, when I removed the stylet to verify my suspicion, there was no flow of CSF. The next "dural puncture" was likely not a dural puncture after all. Although there was flow of CSF from the tuohy, no level was achieved. My explanation for this is that a pool of CSF must have built itself up in the epidural space from the initial dural puncture. I therefore, had plenty of CSF flow and could withdraw CSF prior to injection, but the injection was placed into the epidural space. The very slight relief of pain that occurred just a few minutes after my "spinal injection" is likely attributed to some medication finding its way through the dural tear into the IT space. In hind site, and going forward, I will always make my first attempt at spinal anesthesia with the standard 25 g spinal needle (pencil point type). In this case, I did have some redemption in choosing the tuohy first for two reasons: 1) I had had to resort to a touhy in the previous spinal after multiple failed attempts with the spinal needle and this had solved immediately my difficulty with gaining access to the IT space, and 2) we had 5 inch gertie marx needles (pencil point styled) which are meant to be inserted through the touhy after gaining access to the epidural space, but I only 3.5 inch 25 G spinocan needles for a straight IT approach. (BTW, i have since talked to the anesthesia tech to ensure that we have a large supply of 25G whitacre needles in each OB OR).
In summary, in one night on OB call, I performed 3 anesthetics. Case one was a straight forward very forgettable spinal anesthetic that resulted in an early and severe PDPH requiring blood patch. Case two was a severe PIH patient with very low platelets that underwent uneventful spinal anesthesia despite unfavorable anatomy using a pencil point spinal needle with no sequelae. Case three was a healthy breech twin parturient in extreme pain who suffered a dural puncture with 18G touhy needle with accompanied failed SAB requiring conversion to GETA via RSI. She developed a PDPH 36 hours after puncture and eventually requested a blood patch which resolved her headache.
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Blog with interesting cases and/or problems related to anesthesia with discussion based on best evidence in the literature.